AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Coarctation of the aorta (CoA) is a relatively common defect that accounts for 5-8% of all congenital heart defects. CoA may occur as an isolated defect or in association with various other lesions, most commonly bicuspid aortic valve and ventricular septal defect (VSD). The diagnosis of CoA may be missed unless an index of suspicion is maintained, and diagnosis is often delayed until the patient develops congestive heart failure (CHF), which is common in infants, or hypertension, which is common in older children. This article discusses the pathology, pathophysiology, clinical features, noninvasive and invasive evaluation, and therapy in patients with CoA.

Pathologic anatomy

CoA may be defined as a constricted aortic segment that comprises localized medial thickening with some infolding of the medial and superimposed neointimal tissue. The localized constriction may form a shelflike structure with an eccentric opening or may be a membranous curtainlike structure with a central or eccentric opening. The coarctation may be discrete, or a long segment of the aorta may be narrowed; the former is more common.

In the past, CoA has been described as preductal (or infantile) type or postductal (or adult) type, depending on whether the coarctation segment is proximal or distal to the ductus arteriosus, respectively. However, a closer examination of the anatomy suggests that all coarctations are juxtaductal.

The classic CoA is located in the thoracic aorta distal to the origin of the left subclavian artery at about the level of the ductal structure. However, rarely, a coarcted segment is present in the lower thoracic or abdominal aorta. In such instances, the coarcted segment may be long and fusiform with irregular lumen; many consider these to be inflammatory or autoimmune in origin, and they may be variants of Takayasu arteritis.

Dilatation of the descending aorta immediately distal to the coarctation segment (poststenotic dilatation) is usually present. A jet lesion on the wall of the aorta distal to the coarctation site may also be present. Varying degrees of hypoplasia of the isthmus of the aorta (the portion of the aorta between the origin of the left subclavian artery and ductus arteriosus) are present in most patients with thoracic coarctation; this hypoplasia may be significant in symptomatic coarctation of the neonate and infant, while, in children and adults, the isthmus may have only mild narrowing. The transverse aortic arch (the arch between the origin of the right innominate artery and the left subclavian artery) is also hypoplastic in symptomatic neonates and infants. Collateral vessels that connect arteries from the upper part of the body to the vessels below the level of coarctation may be seen; these may be present as early as a few weeks to a few months of life.

The most commonly associated clinically significant defects include patent ductus arteriosus, ventricular septal defect, and aortic stenosis. The earlier the infant presents, the more likely a significant associated defect is present. Bicuspid aortic valve may be seen in nearly two thirds of infants with CoA, while only 30% of those infants have an older sibling with such an anomaly.

Mitral valve anomalies, although less common than those of the aortic valve, are also associated with CoA. Sometimes, CoA is a complicating feature of a more complex cyanotic heart defect, such as transposition of the great arteries, Taussig-Bing anomaly, double-inlet left ventricle, tricuspid atresia with transposition of the great arteries, and hypoplastic left heart syndrome. Aortic coarctation is extremely rare in patients with severe right ventricular outflow tract obstructions such as tetralogy of Fallot and pulmonary atresia with intact ventricular septum. Some patients with CoA may have cerebral aneurysms, predisposing them to cerebrovascular accidents with severe hypertension later in life. CoA is the most common cardiac defect associated with Turner syndrome.

Pathogenesis

The exact mechanism by which aortic coarctation is produced is not clearly understood. The most commonly invoked hypotheses include hemodynamic and ectopic ductal tissue theories. In the hemodynamic theory, an abnormal preductal flow or abnormal angle between the ductus and aorta that increases right-to-left ductal flow and decreases isthmic flow potentiates development of coarctation. Postnatal spontaneous closure of the ductus arteriosus completes the development of aortic obstruction.

A high incidence of CoA in patients with congenital heart defects and decreased antegrade aortic flow in utero and virtual absence of CoA in patients with right heart obstructions would lend credence to the hemodynamic theory. Abnormal extension of ductal tissue into the aorta (ectopic ductal tissue) has been postulated to create the coarctation shelf and, with ductal closure, development of aortic obstruction. This theory, however, does not explain the variable degrees of isthmus and aortic arch hypoplasia associated with CoA.

Pathophysiology

CoA imposes significant afterload on the left ventricle (LV), which results in increased wall stress and compensatory ventricular hypertrophy.

The afterload may be imposed acutely, as occurs following closure of the ductus arteriosus in neonates with severe coarctation. These infants may rapidly develop CHF and shock. Rapid constriction of the ductus arteriosus, producing sudden severe aortic obstruction, seems to be the most likely explanation. As the ductus (aortic end) constricts, the left ventricular afterload rapidly increases, with a resultant increase in left ventricular pressures (systolic and diastolic). This causes elevation of the left atrial pressure, which may open the foramen ovale, causing left-to-right shunt and dilatation of the right atrium and right ventricle. If the foramen ovale does not open, pulmonary venous pressures and pulmonary artery pressures increase, and right ventricular dilatation develops. Cardiomegaly revealed by chest roentgenography and right ventricular hypertrophy seen on ECG and echocardiography are related to the indirect effects of rapid development of severe aortic obstruction.

LV afterload may also increase gradually, allowing children with less severe coarctation to develop arterial collateral vessels that partially bypass the aortic obstruction. These children may be asymptomatic until hypertension is detected or another complication develops.

The mechanism for development of hypertension is not clearly understood; mechanical obstruction and renin-angiotensin–mediated humoral mechanisms have been postulated.

The mechanical obstruction theory explains the increased blood pressure by postulating that a higher blood pressure is required to maintain flow through the coarcted segment and collateral vessels. The stroke volume, ejected into the limited aortic receptacle, produces a higher pressure proximal to coarctation. However, this theory does not explain the following:

• The lack of relationship between the degree of elevation of blood pressure and the magnitude of obstruction
• The increased peripheral vascular resistance distal to the site of obstruction
• The delayed or lack of reduction of blood pressure immediately following relief of obstruction

The humoral theory postulates activation of the renin-angiotensin system secondary to reduction of renal blood flow and appears to explain most of the clinical features. However, measurement of plasma renin activity in both animal models and human subjects did not show consistently elevated plasma renin levels in the early studies. The reasons for the inability to demonstrate elevation of renin levels may be related to inadequate measurement of salt intake, posture, extracellular fluid volume, and sympathetic influences on renin release. More recent studies demonstrated abnormalities in renin-angiotensin-aldosterone systems. In addition, activation of central sympathetic nervous system may also be responsible for hypertension of aortic coarctation.

Associated anomalies greatly influence pathophysiology. VSD often coexists, and coarctation exacerbates the associated left-to-right shunt. Other levels of left heart obstruction (aortic stenosis, subaortic stenosis) may be present and may add to LV afterload.

A number of neurohumoral changes occur with CHF. Sympathetic nervous system activation occurs, resulting in increases in heart rate and blood pressure (BP). The renin-angiotensin system is activated in patients with CHF, particularly in CoA in which lower-body BP and renal perfusion may be reduced. Activation of the renin-angiotensin system results in vasoconstriction, cell hypertrophy, and the release of aldosterone. The role of the renin-angiotensin system in CHF and the use of drugs to modulate this system are an intense area of research. Unlike most cases of CHF, CoA is more complex because precoarctation and postcoarctation hemodynamics are quite different.

Drugs typically used to treat patients with CHF, such as angiotensin-converting enzyme inhibitors and, more recently, angiotensin II antagonists, may have adverse effects in patients with CoA. Attempts to achieve a normal precoarctation BP with these drugs may result in inadequate lower-body perfusion and may precipitate renal failure.

Vasopressin is also increased in heart failure, although its major stimulus for release is angiotensin II. Vasopressin affects free water retention and may result in hyponatremia. The vasoconstrictive properties of vasopressin may further elevate BP in coarctation.

Other substances, such as human brain natriuretic peptide (BNP), an endothelin, may be activated by CHF, although their specific role in coarctation has not been studied.

An additional cause of CoA is trauma that results in aortic dissection. Compromise of the true lumen of the aorta can result in the clinical picture of coarctation with reduced lower-extremity pulses. Urgent intervention is required in this circumstance.

Frequency

United States

CoA is a common defect and occurs in 6-8% of patients with congenital heart disease. However, coarctation may be found more frequently in infants who present with symptoms prior to age one year.

International

The prevalence of CoA appears to be lower (<2%) in Asian countries than in European and North American countries.

Mortality/Morbidity

Past autopsy studies suggest that the mortality rate in patients in whom CoA is not repaired surgically is 90% by age 50 years, with a mean age of 35 years. In the current era, CoA mortality is often determined by patient age, patient size, and associated major cardiovascular anomalies.

Associated problems that may contribute to death or morbidity include hypertension, intracranial hemorrhage, aortic rupture or dissection, endocarditis, and CHF.

Race

No definitive racial differences have been documented in CoA, although some authors have suggested that CoA is less common in Asians.

Sex

The male-to-female ratio is 2:1, although this ratio is not valid in abdominal CoA, in which this rare lesion predominantly affects females. The ratio of abdominal-to-thoracic coarctation is approximately 1:1000. The male preponderance observed in older patients is not seen in infants with CoA.

Age

Generally, patients with CoA present early in life with CHF or later in life with hypertension. Studies continue to document that CoA is often missed in the first year of life, and the median age of referral to a pediatric cardiologist in one study was 5 years. Among 2192 patients reported to the Pediatric Cardiac Care Consortium from 1985-1993, 1337 were infants, 824 were children, and 31 were adults.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

The presentation of patients with coarctation of the aorta (CoA) varies but may be discussed relative to the patients who present early, often with congestive heart failure (CHF), and the patients who present later, most often with hypertension.

• Early presentation: The presence of associated defects and aortic arch anomalies, the extent of patency of the ductus arteriosus, the rapidity of the process of closure of the ductus arteriosus, and the level of pulmonary vascular resistance determine the timing of clinical presentation and the severity of symptoms. Young patients may present in the first few weeks of life with poor feeding, tachypnea, and lethargy and progress to overt CHF and shock. These patients may have appeared well prior to hospital discharge, and deterioration coincides with closure of the patent ductus arteriosus (PDA). Presentation may be abrupt and acute with ductal closure. Development of symptoms is often accelerated by the presence of associated major cardiac anomalies, such as ventricular septal defect (VSD). Symptoms may be subtle at first, and patients may make repeated trips to the physician before finally presenting in extremis.
• Late presentation: Patients often present after the neonatal period with hypertension or a murmur. These patients often have not developed overt CHF because of the presence of arterial collateral vessels. Diagnosis is often made after hypertension is noted as an incidental finding during evaluation of other problems, such as trauma or more routine illness. Other presenting symptoms may include headaches, chest pain, fatigue, or even life-threatening intracranial hemorrhage. True claudication is rare, although an occasional child may experience pain or weakness in the legs. Many patients are asymptomatic except for the incidentally noted hypertension. Frequently, CoA is not recognized by the primary care physician. Palpation of femoral pulses and measurement of blood pressure during routine examination is necessary to avoid a delay in the diagnosis.

Physical

As with history, physical examination may conveniently separate patients into 2 groups: those who present early with heart failure and those who present later with hypertension.

• Early presentation
• • Neonates may be found to have tachypnea, tachycardia, and increased work of breathing and may even be moribund with shock. Keys to the diagnosis include blood pressure (BP) discrepancies between the upper and lower extremities and reduced or absent lower extremity pulses to palpation. However, when the infant is in severe heart failure, all pulses are diminished. Upon treatment for heart failure, prominent brachial pulses with weak or nonpalpable femoral arterial pulses may be discerned. Diminished pulses on examination should never be disregarded, since the digits appreciate the rate of change in BP, which may be diminished in ductally dependent coarctation, although the measured BP may not show discrepancies. In patients with an aberrant origin of the right subclavian artery from the aorta distal to the obstruction, such discrepancies in BP may not be present, although lower extremity pulses are diminished versus the carotid pulses.
  • Differential cyanosis (pink upper extremities with cyanotic lower extremities) may occur when right-to-left shunt across a PDA provides flow to the lower body. Although often not obvious to the eye, differential cyanosis may be documented based on preductal and postductal pulse oximetry measurements and careful inspection. However, in the presence of lesions with large left-to-right shunt (eg, VSD), pulmonary artery saturations may approximate aortic saturations with less obvious differential oximetric findings. Reversed differential cyanosis (upper body cyanosis with normal lower-body saturation) may occur with transposition of the great arteries, PDA, and pulmonary hypertension, resulting in right-to-left ductal shunting.
  • In low cardiac output and ventricular dysfunction, pulses may be diminished diffusely, and BP gradients may seem minimal. Thus, in addition to coarctation, the differential diagnosis of perinatal circulatory insufficiency always includes left ventricular (LV) outflow obstruction, including aortic valve stenosis, subaortic stenosis, and supravalvar aortic stenosis, as well as severe mitral stenosis or insufficiency.
  • The murmur associated with CoA may be nonspecific yet is usually a systolic murmur in the left infraclavicular area and under the left scapula. Additional murmurs that result from the presence of associated abnormalities, such as VSD or aortic valve stenosis, may also be detected. An ejection click may signify the presence of a bicuspid aortic valve, while a gallop rhythm may indicate ventricular dysfunction.
• Late presentation
• • Older infants and children may be referred for evaluation of hypertension or murmur. Hypertension in a fussy infant or a child may be attributed to agitation; thus, comparing 4 BP readings in the extremities is important. Occasionally, the left arm pressure is lower than the right arm pressure if the origin of the left subclavian artery is involved in the coarctation. Similarly, anomalous origin of the right subclavian artery (below the level of coarctation) may produce decreased or absent right brachial pulse. Careful simultaneous palpation of upper and lower extremity pulses may help confirm suspected coarctation.
  • In older children, adolescents, and adults, CoA is best diagnosed clinically based on simultaneous palpation of femoral and brachial pulses. Blood pressure in both arms and one leg must be determined; a pressure difference of more than 20 mm Hg in favor of the arms may be considered evidence of CoA.
  • A murmur in the left infraclavicular area and under the left scapula may be systolic, but the murmur may also sound continuous in the presence of multiple collateral vessels or, occasionally, severe coarctation. An ejection click may be audible when an associated bicuspid aortic valve and a murmur of aortic stenosis or insufficiency are present. Similarly, a murmur of mitral stenosis or LV outflow tract obstruction may also occur. A gallop rhythm may occur in the presence of a hypertrophic noncompliant LV.
  • Other findings on physical examination may include abnormalities of blood vessels in the retina and a prominent suprasternal notch pulsation. A thrill may be present in the suprasternal notch or on the precordium in the presence of significant aortic valve stenosis. In the rare case of abdominal coarctation, an abdominal bruit may be noted.

Causes

A number of theories exist regarding the etiology of CoA, including postnatal ductal constriction, translocation of ductal tissue onto the aorta, and a theory that alterations in intrauterine blood flow cause altered flow through the aortic arch and result in the substrate for coarctation. CoA manifests when the ductus closes starting at the pulmonary end, with gradual involution of ductal tissue toward the aorta.

Similar to most forms of congenital heart disease (CHD), the etiology of CoA may be explained by multifactorial inheritance hypothesis. The prevalence of CoA in genetic abnormalities such as Turner syndrome (45,X), is as high as 15-20%. Familial patterns of inheritance of coarctation have been reported, as well as for other left heart obstructive lesions. An increase in seasonal occurrence of CoA is reported in September and November.

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Trauma with aortic dissection

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Laboratory studies in neonatal patients who present in shock include the following:
• • Septic workup includes blood, urine, and cerebral spinal fluid (CSF) cultures.
  • Electrolyte levels, BUN, creatinine, and glucose concentrations should be tested.
  • Measure arterial blood gases and serum lactate levels.
• Laboratory studies in older patients who present with hypertension include urinalysis, electrolyte levels, BUN, creatinine, and glucose concentrations.

Imaging Studies

• Chest radiography
• • Radiography in patients with early onset of coarctation of the aorta (CoA) may reveal cardiomegaly, pulmonary edema, and other signs of CHF.
  • Radiography in patients with late onset of CoA may reveal cardiomegaly. An inverted "3" sign of the barium-filled esophagus or a "3" sign on a highly penetrated chest radiograph (frontal view) may be visualized. Rib notching secondary to collateral vessels may also be seen.
• Echocardiography delineates intracardiac anatomy and allows assessment of associated significant intracardiac anomalies. The suprasternal notch 2-dimensional echocardiographic view allows evaluation of the aortic arch to assess the transverse aortic arch, isthmus, and severity of coarctation. Doppler echocardiography is used to measure the gradient at the site of coarctation and to identify the pattern of diastolic runoff typically seen in patients with severe obstruction.
• Instantaneous peak pressure gradients across the aortic coarctation can be estimated with a modified Bernoulli equation, as follows:

  ΔP = 4 (V₂² – V₁²)

  ΔP is the peak instantaneous gradient, and V₂ and V₁ are the peak flow velocities in the descending aortic, distal to coarctation (continuous-wave Doppler) and proximal to the coarctation (pulsed Doppler), respectively. The calculated gradient usually overestimates the measured blood pressure gradient. Presence of pan- diastolic flow indicates significant obstruction. Inclusion of duration-related Doppler flow parameters in the gradient calculation may improve the accuracy of Doppler prediction of coarctation gradient (Rao, Am Heart J, 1989).

• MRI and CT are useful in older or postoperative patients to assess residual arch obstruction, arch hypoplasia, or formation of aneurysms. Ultrafast CT scan is preferable if multiple surgical clips or a stent is present in the area of coarctation.

Other Tests

• Electrocardiography
• • ECG in the neonate or infant with early onset of CoA may reveal right ventricular rather than LV hypertrophy. The reasons for right ventricular preponderance in the face of LV outlet obstruction are mentioned in Pathophysiology.
  • ECG findings in patients with late onset of CoA may be normal or may reveal LV hypertrophy and may show signs of LV ischemia or strain. Sometimes, LV hypertrophy may manifest as increased S waves in leads V₅ and V₆, the so-called posterobasal LV hypertrophy.
• Preductal and postductal pulse oximetry readings may show evidence of ductal right-to-left shunting, especially in the neonate.

Procedures

• Cardiac catheterization
• • Cardiac catheterization and selective cineangiography may not be required for diagnosis; however, they allow evaluation of the severity of coarctation, anatomic nature of the aortic obstruction (discrete vs long segment), and arch anatomy, including hypoplasia of the transverse arch or isthmus.
  • Cardiac catheterization helps confirm the diagnosis when echocardiography findings are not completely clear.
  • Cardiac catheterization allows the evaluation of intracardiac anatomy and the contribution of associated lesions to the overall hemodynamic disturbance.
  • Cardiac catheterization is a prerequisite for intervention in the form of either balloon angioplasty or stent implantation in native or recurrent coarctation.
  • When catheterization is performed, elevations of left ventricular and ascending aortic peak systolic pressures with a peak-to-peak systolic pressure gradient across the coarcted segment are usually found. A peak-to-peak gradient in excess of 20 mm Hg is generally considered indicative of significant obstruction. However, the magnitude of the gradient is not necessarily indicative of the degree of narrowing because the gradient depends on not only the extent of aortic narrowing but also the size and number of collateral vessels. In addition, cardiac output and the state of ductus arteriosus, particularly in the neonate and young infant, also determine the pressure gradient.
  • Selective aortic root or aortic arch angiography is necessary to clearly demonstrate the aortic narrowing. Aortography is useful in demonstrating the type of aortic coarctation (diffuse, long segment, aortic kinking [pseudocoarctation]); extent of collateral circulation; the size of ductus arteriosus, if patent; and the presence and degree of hypoplasia of transverse aortic arch and aortic isthmus, especially in neonates. If thoracic coarctation is not demonstrated despite clinical features of coarctation or if neurofibromatosis is suspected, abdominal aortography may be needed to demonstrate (or exclude) abdominal coarctation.
  • LV angiography is particularly useful in neonates and infants who demonstrate ventricular septal defects and in evaluating their function.

Histologic Findings

CoA results from marked ridgelike thickening of the media of the aortic wall opposite the insertion of the PDA or ligamentum arteriosum. Intima in this area may be thin initially but may thicken over time. This ridge or shelf becomes an obstruction when the patent ductus involutes and when ductal tissue in the wall of the aorta involutes.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical Care

• Early presentation
• • Treatment in patients with congestive heart failure (CHF) includes the use of diuretics and inotropic drugs.
  • Prostaglandin E1 (0.05-0.15 mcg/kg/min) is infused intravenously to open the ductus arteriosus.
  • Ventilatory assistance is provided to patients with markedly increased work of breathing.
  • Infusion of inotropic drugs (dopamine, dobutamine, epinephrine) is useful when ventricular dysfunction is present, especially with hypotension.
  • A Foley catheter is inserted to monitor renal perfusion and urine output.
  • Arterial blood gases are tested to monitor acidosis.
  • An umbilical artery catheter may be placed in neonates to assess the response to prostaglandin infusion with regard to improving lower-body blood flow.
  • Patients stabilized by the above interventions are better candidates for surgical or catheter intervention.
  • In the presence of associated defects, the significance of coarctation on the clinical course of the patient should be assessed with echo-Doppler and/or catheterization and angiographic studies. If the coarctation has a significantly adverse effect on the physiology of the associated defects, and consequently the clinical status, the coarctation should be relieved initially with surgery or balloon and the patient reassessed with regard to need for intervention for the associated defects. Based on the authors' experience and that of others, the aortic obstruction is usually a major contributing factor for the symptomatology, and relief of the obstruction may postpone or avert the need for additional surgical intervention for the associated cardiac defects.
• Late presentation
• • Treatment of hypertension
    • Preoperative hypertension can be effectively treated using beta-blockers. The goal should be to reduce upper extremity hypertension, but remember that vigorous attempts to achieve normal upper extremity blood pressure (BP) may result in inadequate lower-body perfusion. Beta-blocker therapy prior to surgery may reduce the severity of postoperative hypertension, although most patients with preoperative hypertension require at least transient postoperative therapy. Remember that relieving the aortic obstruction promptly rather that attempting to treat hypertension with antihypertensive medications is better.
    • Postoperative hypertension can be treated short-term with vasodilators, such as sodium nitroprusside, and intravenous beta-blockers, such as esmolol. When longer-term antihypertensive therapy is required, beta-blockers may be continued, and if no residual arch obstruction exists, ACE inhibitors or angiotensin II antagonists (pediatric dosing not established for angiotensin II antagonists) may be added if hypertension persists despite beta-blocker therapy.
  • Evaluate associated abnormalities, such as aortic stenosis, subaortic stenosis, or mitral valve disease.
  • Evaluate adequacy of collateral blood vessels to assess the safety of surgical intervention.

Surgical Care

Significant hypertension or congestive heart failure is an indication for intervention. Surgical relief of the aortic obstruction and catheter interventional techniques (balloon angioplasty and stents) are available alternatives. Symptomatic neonates and infants should undergo urgent intervention soon after the infant is stabilized. Asymptomatic infants, children, adolescents, and adults should undergo the procedure electively. If neither hypertension nor heart failure is present, elective surgical or balloon therapy in children aged 2-5 years is suggested. After age 5 years, surgery or balloon therapy to relieve an aortic obstruction is not advisable because of the evidence of residual hypertension.

Since the introduction of surgical correction by Crafoord and Nylin and by Gross and Hufnagel in the early 1940s, surgical therapy has been the preferred treatment for aortic coarctation. Various surgical techniques have been used to treat patients with coarctation of the aorta (CoA), namely, resection and end-to-end anastomosis, patch aortoplasty, left subclavian flap aortoplasty, and tubular bypass grafts. The techniques are occasionally combined or modified to fit the individual patient's anatomy.

For instance, a reverse left subclavian flap aortoplasty may be used, turning the left subclavian artery as a patch back toward the left carotid artery to enlarge an area of transverse arch hypoplasia. In addition, an extended end-to-end repair may be used, in which the segment of descending aorta is beveled and brought up to the underside of the transverse arch to enlarge areas of transverse arch hypoplasia. The exact technique used varies depending on the patient's age at presentation, size, associated abnormalities, and arch anatomy. A surgical approach from a median sternotomy, rather than the classic left lateral thoracotomy, is used commonly in complex arch repairs.

• In a review of 1337 patients undergoing repair of coarctation in infancy (Norton, 1998), the following findings were reported:
• • Subclavian flap aortoplasty was performed in 763 patients (57%). Resection in end-to-end anastomosis was used in 406 patients (30%), and patch aortoplasty was used in 133 patients (9.9%). In addition, 20 patients underwent placement of an interposition graft or bypass graft.
  • In the series, the mortality risk was highest in neonates in whom surgery was performed during the first week of life, while only 8 of 279 infants aged 3 months to 1 year who underwent surgery died. Mortality associated with surgery was also higher in smaller infants, particularly in infants who weighed less than 3 kg and infants with associated cardiac anomalies.
  • The presence of a ventricular septal defect (VSD) with or without minor associated anomalies increased the risk of death from 0.9% (no anomalies) to 6.8% (with VSD). Complex associated anomalies, such as a single ventricle or transposition of the great arteries, greatly increased the mortality rate to 16.6%. Similarly, the surgical mortality rate in neonates who required surgery prior to coarctation repair was 45%. Urgent surgery may be required if the patent ductus arteriosus (PDA) cannot be opened and the patient continues to have poor urine output and acidosis.
• In the presence of a hemodynamically significant VSD, historically, placement of a pulmonary artery band was performed to limit pulmonary blood flow at the time of left thoracotomy for coarctation repair. Current surgical approach uses a single-stage repair of the coarctation and VSD, usually through a sternotomy, even in the small neonate.
• In severe transverse arch hypoplasia that results in significant residual obstruction following coarctation repair, an ascending-to-descending aortic conduit may be placed. This is usually a less favorable approach, since the patient may be obligated to undergo subsequent surgeries for conduit replacement.
• In most centers, associated defects may be addressed at the time of surgery for coarctation by proceeding with a median sternotomy to repair lesions such as mitral stenosis or subaortic obstruction or to accomplish left ventricular (LV) outflow tract enlargement. Occasionally, the adequacy of the LV volume is called into question, and the patient may require a modified Norwood repair. Decision making about this issue is addressed in Hypoplastic Left Heart Syndrome. However, note that hypoplasia of the left heart structures, particularly the LV, associated with isolated CoA usually improves following relief of aortic obstruction.
• Repair of coarctation in the asymptomatic child or adolescent is usually undertaken on an elective basis after assessment of associated anomalies and appropriate preoperative evaluation. The timing of intervention in the otherwise asymptomatic patient has been debated. The rationale for delaying surgery until age 3-5 years has been based on the size of the aorta in childhood relative to the anticipated adult size. Since significant obstruction occurs when the diameter of the aorta is reduced by 50% or more, delaying surgery until age 3-5 years allows the aorta to be larger than half the anticipated adult size at operation, theoretically reducing the risk of significant residual obstruction in the event that the surgical repair site does not grow over time. However, issues of hypertension, progressive LV hypertrophy, or LV dysfunction mandate earlier repair.
• Improvements in surgical techniques have led most cardiologists to recommend surgery at the time of diagnosis, especially in patients with hypertension. In patients with only mild obstruction, especially those diagnosed in the first year of life, surgery may safely be delayed and the patient monitored for worsening obstruction or development of hypertension prior to recommending surgery.
• Pseudo-CoA refers to abnormal tortuosity of the aorta that does not result in significant obstruction or hypertension and is noted for the lack of development of collateral vessels. This abnormality does not require surgical intervention.
• Surgical repair of CoA is accomplished in children and adolescents with generally good results and low mortality. Of 824 patients who underwent coarctation repair in childhood, 431 (52%) underwent end-to-end anastomosis, while patch aortoplasty was performed in 214 patients (26%) and only 109 patients (13%) underwent subclavian flap aortoplasty. Death occurred in only 6 of 824 patients for a total mortality rate of 0.73% (Norton, 1998). The surgical era of this cohort would not reflect the current surgical strategy for aggressive complete arch repair or the aorta and all associated lesions. The trend is toward the less frequent use of patch aortoplasty because of concerns regarding the development of aortic aneurysm at the site of repair.
• Operative mortality rates in neonates and infants are high (4-50%), while the operative mortality rates in older children are low (0-5%). The high mortality in the young infant appears to be related to the condition of the infant at the time of surgery and the associated defects.
• Significant recoarctation (6-33% in infants, 0-18% in older children); formation of aneurysms in all types of coarctation repair, particularly well-documented following prosthetic patch angioplasty; development of paraplegia; paradoxical hypertension; and vascular complications related to subclavian flap repair continue to be problems. Despite these problems, surgical repair is considered by many to be the therapeutic option of choice in the treatment of aortic coarctation. Some groups of workers, including the authors' group, consider balloon angioplasty the initial therapy of choice (see Balloon angioplasty) and reserve surgical intervention for the following coarctations:
• • Coarctations that involve the long segment of the aorta
  • Coarctations that are completely or almost completely occluded so that no catheter or guidewire can be passed across the coarcted segment
  • Coarctations that are associated with a large patent ductus arteriosus and ventricular septal defect that requires prompt surgical intervention for the primary cardiac problem
• Balloon angioplasty: Gruntzig's technique of balloon angioplasty was adopted by Sos et al, Singer et al, and Sperling et al for enlargement of coarcted aortic segments in a postmortem specimen, postsurgical recoarctation, and native coarctation, respectively. Other cardiologists then used this technique to treat native CoA. A number of investigators reported their experiences with balloon angioplasty of native aortic coarctations. This section describes the technique and the results of balloon angioplasty.
• • Technique
  • • Cardiac catheterization and selective cineangiography are performed to confirm the clinical diagnosis, to exclude other cardiac defects, and to assess suitability for balloon angioplasty. Once balloon angioplasty is chosen, a 4F-6F multi-A2 (Cordis) catheter is introduced into the femoral artery percutaneously and is positioned across the aortic coarctation. Then, a 0.032-0.035 in J-tipped guidewire is passed through the catheter into the ascending aorta and the tip of the wire positioned in the ascending aorta. A 4F-7F balloon angioplasty catheter is then positioned across the aortic coarctation. The balloon is inflated with diluted contrast material to approximately 3-5 atm of pressure or higher, depending on the manufacture's recommendations.
    • Monitoring pressure of inflation via any of the commercially available pressure gauges is recommended. The balloon is inflated for 5 seconds. A total of 2-4 balloon inflations are performed 5 minutes apart. Aortography and measurement of pressure gradients across the CoA are performed. The heart rate, systemic pressure, and cardiac index are recorded prior to and 15 minutes after balloon dilatation to ensure that the change in pressure gradient is related to balloon dilation rather than changes in patient status.
    • The authors generally perform this procedure with the patient under conscious sedation, while others advocate general anesthesia. Most cardiologists use percutaneous femoral artery approach for cardiac catheterization and balloon angioplasty. Occasionally, femoral artery cutdown or left axillary artery cutdown is necessary if the percutaneous approach is unsuccessful. The authors and others have used a transumbilical approach in neonates in an attempt to avoid the use of the femoral arteries. In patients in whom the aorta can be entered from the right ventricle (either directly in patients with transposition of the great arteries or double outlet right ventricle or indirectly through a ventricular septal defect), balloon angioplasty may be performed transvenously.
    • The size of the balloon chosen for angioplasty is 2 or more times the size of the coarcted segment, but no larger than the size of the descending aorta at the level of the diaphragm, as measured from a frozen video recording. The authors usually choose a balloon that is midway between the size of the aortic isthmus (or transverse aortic arch) and the size of the descending aorta at the level of diaphragm. If the relief of obstruction is not adequate (pressure gradient reduction to <20 mm Hg and angiographic improvement), a balloon as large as the diameter of the descending aortic at the level of diaphragm is chosen for additional dilatation.
    • The authors usually give 100 U of heparin per kilogram prior to introducing the balloon-angioplasty catheter. Activated clotting times should be measured every 30 minutes and maintained between 200 and 250 seconds. The heparin effect is neither reversed nor continued after the procedure. Administering adequate doses of heparin to prevent thromboembolism is important
    • The balloon inflation pressure should be monitored and attempts made not to exceed that stated by the manufacturer; this is to prevent balloon rupture and its adverse effects.
    • A catheter or a guidewire must not be manipulated over the site of a freshly dilated CoA. A guidewire should always be left in place across the coarctation segment, and all angiographic and balloon-dilatation catheters should be exchanged over the guidewire.
    • Balloon size should be carefully chosen (see above) to prevent aneurysm.
    • Use of large-caliber angioplasty catheters may result in significant femoral artery compromise. Availability of balloon catheters that can be introduced through 4F sheaths appears to reduce the femoral artery injury. Even these may injure the femoral artery in the young infant; in such situations, the authors use 3F sheaths through which the more recently available balloon dilatation catheters (eg, Mini-Tyshak [Braun] catheters) can be introduced, which may further reduce such complications.
  • Short-term results
  • • Despite an initial report of poor results, subsequent experience with balloon angioplasty appears encouraging and has been detailed elsewhere (Rao, Clin Cardiol, 1989; Rao, J Am Coll Cardiol, 1996). A reduction of pressure gradient across the coarctation and an increase in the size of the coarcted segment have been observed. The collateral vessels diminish promptly. The femoral pulses, which had been either absent or markedly reduced and delayed (when compared with brachial pulses) become palpable with increased pulse volume after balloon angioplasty.
    • The infants who were in heart failure improved, as did their hypertension. The infants who were ventilator dependent could be weaned off of the ventilator support and were extubated. Most infants (beyond the neonate period) and children are discharged from the hospital within 24 hours after balloon angioplasty. None of the authors' patients required immediate surgical intervention.
  • Intermediate-term follow-up results
  • • Several investigators have reported 1- to 2-year follow-up results, and these studies suggest continued improvement. From the authors' study (Rao, Am Heart J, 1996), 60 patients (58 catheterization, 2 clinical) were observed; the residual gradients 14 ± 11 (mean ± SD) months following angioplasty remained low at 16 ± 15 mm Hg. These gradients continue to be lower (P <.001) than those prior to angioplasty (46 ± 17 mm Hg) and are slightly higher (P <.05) than the gradients (11 ± 9 mm Hg) immediately following angioplasty. The angiographically measured coarctation segment remained wide. Only a modest increase is found (11 ± 9 vs 16 ± 15 mm Hg; P <.05) in peak gradients for the group as a whole, but, when individual patient values are examined, 15 (25%) of the 60 patients had evidence of recoarctation, defined as a peak-to-peak systolic pressure gradient in excess of 20 mm Hg.
    • The incidence of recoarctation is higher in neonates (5 [83%] of 6; P <.01) and infants (7 [39%] of 18; P=.011) than in children (3 [8%] of 36). Ten of these children underwent repeat balloon angioplasty, and their gradients were reduced (P< .001) from 39 ± 11 mm Hg to 10 ± 6 mm Hg. Early in the authors' experience, 2 patients underwent surgical resection with good results. The final 3 children had no discrete narrowing and had no hypertension; therefore, no intervention was recommended. Aneurysms developed in 3 (5%) of 58 patients who underwent follow-up angiography; one of these patients required surgical excision of the aneurysm and the other 2 are observed clinically.
  • Long-term follow-up results
  • • Only scant data can be found on long-term follow-up after balloon angioplasty of native coarctation. Despite recoarctation and aneurysms, some requiring repeat intervention at intermediate-term follow-up, the long-term follow-up results (5-9 y) appear encouraging, in that minimal incidence of late recoarctation and no late aneurysm formation was found.
    • Event-free survival curves following initial balloon angioplasty suggest that the event-free rates are better (P <.001) in children than in infants and neonates. In most children, the arm blood pressure remained normal and the blood pressure–determined gradient between arms and legs remained low.
  • Applicability in adult patients
  • • Although balloon angioplasty of aortic coarctation has most frequently been used in neonates, infants, and children, it can also be used in adult patients.
    • Lababidi et al were the first to apply this technique in a 27-year-old man, resulting in reduction of peak systolic pressure gradient across the coarctation (from 70 to 15 mm Hg), angiographic improvement, and reduced hypertension (190/124 mm Hg vs 130/80 mm Hg). They subsequently reported their experience with balloon dilatation of native coarctation in 8 consecutive adults, aged 19-30 years (25 ± 5 y). The systolic pressure gradient across the coarctation was reduced from 48 ± 19 mm Hg to 7 ± 5 mm Hg. The size of the coarcted segment increased from 6.8 ± 2.2 mm to 15.2 ± 5.0 mm.
    • No complications were encountered. Clinical and echo-Doppler follow-up one year after the procedure revealed good results, with no more than 15 mm Hg peak systolic blood pressure difference between the arms and the legs (measured by cuff). They concluded that results in young adults are similar to those observed in children, balloon angioplasty should be considered as an option to surgical intervention, and follow-up studies (>1 y) are required.
    • Following reports revealed equally good results (Rao, Current Cardiol Reports, 2005). Based on a review of these studies, aortic perforation during the procedure and aneurysmal formation at follow-up are also apparent in adults. In addition, intimal dissection that persisted at 6-month follow-up was seen in one patient. Therefore, (1) avoiding manipulation to the tips of the catheters and guidewires in the region of freshly dilated coarctation, (2) choosing an appropriate-sized balloon (no larger that the diameter of the descending aorta at the level of the diaphragm), and (3) monitoring for the development of aneurysms and, if found, closely following the progression of aneurysms with repeated angiography or magnetic resonance imaging are prudent guidelines.
  • Surgery compared with balloon therapy
  • • Scant data are available to compare surgical intervention with balloon angioplasty. In an attempt to compare the safety and efficacy of balloon angioplasty with surgical correction of aortic coarctation, the authors scrutinized 49 papers (published from 1980-1991) that reported on results of surgery in infants younger than 1 year and 9 papers that compared the results of balloon angioplasty in children (Rao, Ann Thorac Surg, 1991; Rao, Transcatheter Therapy in Pediatric Cardiology, 1993). These data showed that recoarctation rates are similar, whereas the mortality rates are slightly higher in the surgical than the balloon angioplasty series. Similar comparison of results in children older than 1 year showed identical results.
    • Shaddy and associates prospectively randomized 36 patients aged 3-10 years to undergo either balloon angioplasty (20 patients) or surgery (16 patients) and found similar immediate pressure gradient relief in both groups. The risks of aneurysm formation and restenosis were higher in the balloon angioplasty group, while risks of neurologic complications were higher in the surgical group. They concluded that balloon angioplasty in CoA may provide an effective initial alternative to surgery in children beyond infancy and suggested that further follow-up is needed to evaluate the long-term risks of aneurysms following angioplasty.
    • The authors compared the efficacy and safety of balloon angioplasty with those of surgical correction in infants older than 3 months (Rao, 1994). Data on 29 infants who underwent intervention for aortic coarctation from 1982-1992 were examined. Fourteen infants underwent surgical repair, while 15 underwent balloon angioplasty. The data indicated that the degree of relief of aortic obstruction and the frequency with which reintervention is needed are similar in both groups. However, balloon angioplasty carries lower morbidity rates and complications than with surgical therapy. Based on these data, the authors suggested that balloon angioplasty may be an acceptable alternative to surgery in the treatment of symptomatic aortic coarctation in infants younger than 3 months.
    • Complications such as paraplegia and paradoxical hypertension very common following surgical repair, while such complications are rare and, if present, very mild and inconsequential following balloon angioplasty. Aneurysms following balloon angioplasty are of concern and need further study, although such aneurysms are also seen with surgical repair. The femoral artery occlusion rate following balloon angioplasty may be higher than that seen with surgical therapy. However, vascular complications can occur in the left upper limb following coarctation repair with subclavian flap aortoplasty; these complications include gangrene, reduction in the length and muscle mass of upper arm and forearm, and abnormal Doppler blood flow velocities in brachial arteries, suggesting potential for symptoms of ischemia.
    • Cowley et al compared long-term (mean, 10-11 y) results of balloon angioplasty with those of surgery for patients with native aortic coarctation who were randomized at entry into the study and found similar resting blood pressures, residual gradients across the coarctation, exercise performance, aortic arch anatomy based on MRI angiography, and reintervention rates. However, the incidence of aneurysms and greater arm-to-leg blood pressure difference during exercise was higher in the balloon group than in the surgery group.
    • The authors suggested that surgery is preferable to balloon angioplasty in the management of aortic coarctation in children. Although randomization is a virtue of the study, the study involves only 36 children, with only 21 (58%) returning for reevaluation. Furthermore, other studies in which a larger number of balloon angioplasty procedures were evaluated at long-term follow-up revealed 5% aneurysm formation. Aneurysm formation was also detected in surgical patients. Consequently, a multi-institutional randomized study with a larger number of subjects is in order to resolve the issues brought out by this paper.
    • Based on the above review, the effectiveness of balloon angioplasty appears to be comparable with that of surgery; the mortality rates are similar (and are probably related to the associated cardiac defects, not related to type of intervention performed), and morbidity and complication rates are lower with balloon angioplasty than with surgical therapy. Balloon angioplasty may be an effective alternative to surgery for the relief of aortic coarctation.
  • Recoarctation
  • • Residual and recurrent obstructions cannot be easily distinguished, and the term recoarctation may be used to describe both entities. Recoarctation is defined as a peak-to-peak systole pressure gradient in excess of 20 mm Hg with or without angiographically demonstrable narrowing. Recoarctation following both surgical correction and balloon angioplasty has been described.
    • Recoarctation following surgery does not depend on the type of surgical repair; it has been observed following resection with end-to-end anastomosis, subclavian flap angioplasty, prosthetic patch repair, subclavian artery turn-down procedure, and interposition tube grafts. The reported incidence of recoarctation has varied depending on the study. The average recoarctations rates were 11-17% in neonates and infants younger than 1 year and 5.6% in children older than 1 year. In a large cohort of patients studied by Pinzon et al, recoarctation occurred in 23%. The younger the child at surgery, the higher the chance for recoarctation.
    • Although no consensus has been reached in regard to the method of intervention (surgery vs balloon angioplasty) for native aortic coarctation, cardiologists generally agree that balloon angioplasty is the treatment of choice for postsurgical aortic coarctations. The immediate and follow-up results of balloon angioplasty for postsurgical recoarctation are essentially similar to those of native coarctations and have been reviewed in detail elsewhere (Rao, 1999).
    • Restenosis following balloon angioplasty also appears to be age dependent; the younger the child, the greater the chance for recoarctation. The authors and others recommend repeat balloon dilatations in such cases, while others prefer surgical intervention.
    • The technique of balloon angioplasty for the management of both postsurgical and post–balloon angioplasty recoarctations is similar to that described above for native coarctation.
  • Conclusions: Based on an extensive review of the literature and personal experience with the procedure for more than 20 years, some generalizations with regard to balloon therapy may be made, as follows.
  • • Children older than 1 year and adults with discrete native coarctation are candidates for balloon dilatation. Most cardiologists agree on this issue. Long-segment coarctations or those associated with significant isthmic hypoplasia may be candidates for stent placement, especially in adolescents and adults.
    • Recurrent coarctation following previous balloon angioplasty may be treated with repeat balloon angioplasty; others prefer surgery. If the recoarcted segment is long, surgical treatment in younger children and stents in adolescents and adults seem appropriate.
    • Treatment of coarctation in neonates and infants is perhaps the most controversial issue. Many cardiologists prefer surgical intervention, whereas a few cardiologists may opt for balloon angioplasty.
    • Balloon angioplasty is useful in the treatment of extremely ill neonates and infants with severe coarctation; in this subset of patients, the balloon angioplasty has a significant advantage over a surgical approach.
    • Most surgeons agree that balloon angioplasty is the treatment of choice for postsurgical recoarctations.
• Aortic stents
• • Vascular stenotic lesions can be opened with balloon angioplasty, but, because of the elastic recoil of the vessel wall, the vessel lumen may return to the predilation size following withdrawal of the balloon catheter. Such recoil and vascular dissection following balloon dilatation can be circumvented with implantation of endovascular stents. Dotter, in the late 1960s, suggested this concept and implanted spiral coil-spring prostheses into the experimentally produced peripheral artery stenotic lesions. The stent concept and technology were dormant until the early 1980s, when the balloon-expandable and self-expanding stents were designed and used. Initially, stents were used in the treatment of peripheral arterial disease and coronary artery stenotic lesions in adults. The technique was then extended to the treatment of other stenotic vessels, including aortic coarctation.
  • Despite reasonably good short-term and long-term results of balloon angioplasty, some problems remain, including restenosis, probability of aortic rupture, formation of aneurysms, and inability to effectively treat long-segment tubular narrowing. Because of these and other reasons, endovascular stenting of aortic coarctation has gained acceptance over the last decade. The following are perceived advantages of stents over balloon angioplasty
  • • The ability to expand tubular long-segment coarctation, hypoplastic isthmus, and the distal transverse aortic arch
    • The ability to increase the coarcted segment diameter independently of the intimal tear
    • The ability to decrease the probability of restenosis
    • The ability to prevent dissection of the torn intimal flap by facilitating apposition of the intima against the media
    • The ability to prevent aneurysms because of the support of the weakened aortic wall with the stent and neointima
  • O'Laughlin et al were the first to use a stent for the treatment of aortic coarctation, although the results in a 12-year-old child were marginal. Subsequently, a number of other workers reported the use of a stent in aortic coarctation with encouraging results.
  • Because of growth issues and the need for large sheaths for implantation, most cardiologists limit stent usage to adolescents and adults. The following are indications for using stent:
  • • Long-segment coarctation
    • Associated hypoplasia of the isthmus or aortic arch
    • Tortuous coarctation with malalignment of the proximal and distal aortic segment
    • Recurrent aortic coarctation or an aneurysm following prior surgical or balloon therapy
  • Technique
  • • The authors perform the procedure under conscious sedation, while some cardiologists perform the procedure under general anesthesia. Cardiac catheterization is performed to confirm the clinical and echocardiographic diagnosis and to exclude other cardiac defects. Pressure gradients across the coarctation and selective cineangiography in multiple angiographic projections are initially performed to demonstrate the stenotic lesions.
    • The following measurements are made: (1) the diameter of the stenotic lesion, (2) the diameter of the aorta proximal and distal to the obstructive segment, and (3) the length of the vessel that can be stented. All the measurements are made in 2 orthogonal views and averaged. Foreshortening of the vessel length is taken into account based on the anatomy. These measurements are used in the selection of expanded diameter and length of the stent. Heparin (100 U/kg) is administered, and activated clotting times are monitored and maintained between 200-250 seconds by giving additional doses of heparin, as needed.
    • An end-hole catheter (5F-6F multi-A₂ [Cordis, Miami, Fla]) is positioned across the coarctation with the help of a soft-tipped 0.035-in Bentson (Cook, Bloomington, Ind) guidewire. The guidewire and catheter are advanced into the ascending aorta. The catheter is left in place, and the guidewire is removed and replaced with either an extra-stiff exchange-length 0.035-in Amplatz (Cook) or a super-stiff, short tip, Amplatz (Meditech, Nautik, Mass) guidewire. The catheter is then removed. If the approach to the lesion is tortuous or difficult to reach, the authors select a 0.038-in super-stiff Amplatz wire (Meditech). An appropriate-sized long blue Cook sheath (Cook) with a multipurpose curve and a radiopaque marker at the tip is introduced over the stiff wire. Once the tip of the sheath is past the site intended to be stented, the dilator is removed and the sheath flushed. Sometimes, the dilator has to be withdrawn slightly to position the tip of the sheath at the desired location.
    • The selection of the sheath diameter obviously depends on the size of the stent delivery catheter. The authors have always attempted to select a balloon delivery system that would allow the smallest possible sheath diameter. Initially, when other workers were using Meditech PE-MT balloon catheters, which required11F sheaths, the authors were using Olbert (Meadox-Surgimed, Oakland, NJ) balloon catheters, which can be introduced through 8F or 9F sheaths for mounting the stent. Subsequently, the authors have used Bridge stents (Medtronic AVE, Santa Rosa, Calif), which can also be delivered via 8F or 9F sheaths. Most recently, the authors used IntraStent DoubleStrut stents (ParaMount and DoubleStrut LD; IntraTherapeutics, St. Paul, Minn) and Palmaz Genesis (Cordis Endovascular, Warren, NJ). The latter stents are mounted on balloon-in-balloon (BIB) catheters (NuMed Inc, Hopkinton, NY). The size of the sheath used is 1F larger than the sheath size needed for the BIB catheter.
    • The selected stent is hand crimped onto a BIB catheter; the authors use a sterile umbilical tape to further crimp the stent onto the balloon.
    • The balloon catheter, with the stent mounted on it, is advanced over the stiff guidewire but within the sheath and positioned across the coarctation segment. The tip of the sheath is withdrawn distal to the aortic coarctation based on bony landmarks. Contrast is also injected via the side arm of the blue Cook sheath, and the position of the stent is adjusted as necessary.
    • In cases in which the BIB catheter is used, the inner balloon is inflated at the manufacturer's recommended pressure and the position of the stent adjusted, if needed, followed by inflation of the outer balloon, thus implanting the stent. The balloon catheter is then advanced slightly, centering the balloon across the proximal end of the stent, and the outer balloon is re-inflated to ensure apposition of the stent against the vessel walls. The balloon catheter is then centered over the distal end of the stent. This is performed by advancing the tip of the sheath over the deflated balloon into the stent to prevent inadvertent displacement of the stent. The outer balloon is then re-inflated to ensure apposition of the distal stent against the vessel walls.
    • If the outer balloon diameter is not as large as the desired diameter of the stent, additional balloon expansion with larger diameter balloons is performed. The author always tries to avoid this step by using an outer balloon of the BIB catheter at the desired diameter. Following the removal of the balloon catheter, a multitrack catheter (Braun, Bethlehem, Penn) is positioned over the wire, and pressure pullback tracings and angiography are performed to assess the results of stent implantation.
    • The effect of heparin is not reversed, and no additional doses of heparin are administered. Intravenous cefazolin 25 mg/kg/dose (maximum of 1 g) is started in the catheterization laboratory, and 2 additional doses are administered at 6- to 8-hour intervals. Aspirin in platelet-inhibiting doses (5-10 mg/kg/d) is started on the day following the procedure and continued for 6 weeks. Use of heparin overnight on the day of procedure and more potent platelet-inhibiting drugs or anticoagulation with warfarin (Coumadin) have been undertaken in the past. At present, the data do not indicate the need for intensive anticoagulation. Aspirin alone appears to suffice. However, more potent platelet-inhibiting drugs, such as clopidogrel, may be used in adults.
    • To avoid potential balloon rupture, the tip of the guidewire is placed in the right subclavian artery instead of the ascending aorta, which is the usual practice for balloon angioplasty. Try not to position the stent across the origins of left common carotid artery and left subclavian artery. However, on occasion, avoiding the subclavian artery is impossible. In such situations, the authors have carefully traversed the stent cells (in between the struts) with a soft guidewire followed by a multi-A₂ catheter (Cordis). The stent cell is then dilated with an angioplasty balloon of a diameter equal to that of the proximal left subclavian artery; uncompromised flow to the left subclavian artery was found in these patients. Predilation of the coarcted segment with balloon angioplasty prior to stenting is no longer recommended.
  • Immediate results
  • • The reduction of peak systolic pressure gradients and an increase in the diameter of the coarcted segment have been demonstrated following stent implantation. Stenting was found to be effective in postsurgical and postballoon recoarctations, as well as in native coarctations. The ratio of diameters of coarcted segment to the descending aorta at the level of the diaphragm increased to unity in many patients who undergo aortic stenting. Improvement in the size of hypoplastic isthmus or transverse aortic arch and exclusion of the aneurysm, if present, also occurred after stent placement.
    • In the first series of 10 patients published by Suarez de Lezo et al in 1995, the peak systolic pressure gradient across the coarctation decreased from 43 ± 12 to 2 ± 3 mm Hg (P <.001). The ratio of isthmus/descending aorta increased from 0.65 ± 0.14 to 1 ± 0.08 following the procedure. Similar results have been reported subsequently by other investigators (Rao, Indian Heart J, 2001).
  • Complications
  • • Vessel disruption, displacement of stent, and aneurysms are rare but occur. Balloon rupture that results in inadequate stent expansion and stent migration has been reported but may be prevented by avoiding curvature of the balloon or stent assembly, the use of newer stents with less injurious ends, and the use of BIB catheters. Because of the large size of the sheath required, loss of pulse and bleeding from a puncture site may occur. Use of vascular closure devices may help circumvent this problem. Rare complications included myocardial infarction and retroperitoneal hemorrhage.
• • Follow-up results
  • • Most studies had only a short-term and incomplete follow-up in a limited number of patients. However, a few studies examined results of more than 20 patients at a mean follow-up of 2 years or longer. The pressure gradients across the coarctation site (blood pressure, Doppler, or catheterization) remained low, and systemic hypertension decreased both in degree and frequency with the consequent decrease in the need for antihypertensive medications. No evidence for recoarctation, aneurysmal formation, or stent fracture or displacement was observed, although no systematic or complete follow-up was achieved in most studies.
    •  Residual or recurrent obstruction was present in a few patients, and, in these, successful redilatation with larger balloons was accomplished. Detailed angiographic studies by Suarez de Lezo et al (1999) revealed no detectable neointimal proliferation in 75% of patients; in the remaining patients, focal neointimal ridge formation was observed at the ends of the stent, causing minimal restenosis. Segmental analysis of the aorta revealed an increase in nonstented segments of the aorta, consistent with normal growth. Two young patients (7%) developed small new aneurysms that were obliterated by coil placement following angiographic detection. However, the overall follow-up results were encouraging.
  • Comments
  • • Stent therapy appears to be an attractive method for the treatment of recurrent coarctation or aneurysm formation following prior surgical or balloon intervention and for long-segment hypoplasia. Most cardiologists use stents in adolescents and adults, although a few have advocated their use in younger children. The selection of the type of stent and the type of balloon catheter used for stent deployment appears to be evolving. Balloon-expandable stents are preferred over self-expandable stents.
    • The use of a BIB catheter for stent delivery appears to be gaining momentum in an attempt to prevent balloon ruptures and perforation of other cardiovascular structures. Positioning the guidewire into the right or left subclavian artery may avoid excessive curvature and, thus, may prevent balloon rupture. Flexible instead of rigid Palmaz stents are being used. Selected stent diameter at implantation should be at least twice the diameter of the narrowest aortic segment to prevent stent displacement during implantation. The issues related to placement of the stent across the mouths of the arch vessel still need to be resolved.
    • Relief of obstruction both short-term and at follow-up with a low incidence of major complications is well demonstrated in several studies. Meticulous attention to the technique and adoption of new technology may further reduce the incidence of complications. Recoarctation rate at follow-up appears to be low. Re-expansion of the stent to treat residual or recoarctation and growth-related narrowing appears feasible, safe, and effective, although this is based on limited experience. The few studies that have compared balloon angioplasty with stents suggest that stents may be more effective. Based on the available data, stenting aortic coarctation appears to be the preferred alternative to surgical or balloon therapy in adolescents and young adults.
  • Covered stents
  • • Experience in the use of covered stents to manage aortic coarctation has been extremely limited. Different types of stents to treat aortic coarctation have been used and include Jostent grafts (Jomed International, Helsingborg, Sweden), C-P stents (NuMed Inc, Hopkinton, NY), and AneuRx (Medtronic, Watford, UK). The indications for intervention are similar to those used for balloon angioplasty and deployment of the standard stent.
    • The indications for use of covered stents include postangioplasty aneurysm, tortuous aortic arch and isthmus, associated patent ductus arteriosus, prior surgical conduit, Takayasu arteritis, and extremely narrow (subatretic) coarcted segment. When the assessed risk for development of aneurysm or dissection is high, a covered stent should be used. The results of the limited use of covered stents appear to be good. Some of the stents can be expanded to only an 18-mm diameter. In addition, the stent shortens when expanded to larger diameters. Use of covered stents has another disadvantage in that the vessels that arise from the aorta are blocked.
    • Based on the currently available data, the covered stents may be useful in highly selected patients with aortic coarctation.
  • Future directions
  • • The cellular pathophysiologic mechanisms responsible for recoarctation have not been identified. Once they are identified, appropriate treatment algorithms to prevent recoarctation could be developed to address the pathophysiology. Until such time, keeping coarcted segments open with stents is an attractive option. Unfortunately, the stents, which are metallic, do not grow with the child and cannot be used routinely in neonates and infants.
    • Biodegradable stents may offer a solution; these stents keep the coarcted aortic segment open for a 3- to 6-month period, after which the stents dissolve. By then, the ratio of the normal aortic tissue to abnormal tissue may be in favor of the infant, thus preventing recurrence of significant narrowing. However, this hypothesis should be tested in appropriate animal models and stent delivery systems miniaturized so that they can be used in neonates and young infants.
  • Summary of treatment
  • • At initial presentation, if cardiac failure or hypertension is the presenting problem, it should be addressed to stabilize the patient. Subsequently, the aortic obstruction should be relieved. The available options include surgical and catheter interventional procedures; the latter procedures include balloon angioplasty and bare or covered stents.
    • In general, surgical intervention in neonates and young infants (extremely ill babies with poor left ventricular function may benefit from balloon angioplasty), balloon angioplasty in children, and stent deployment in adolescents and adults appear to be appropriate options. Of course, the anatomy of the coarcted aortic segment and the aortic arch would greatly influence the method of therapy in a given patient.

Consultations

• Early presentation
• • In infants who present early with CHF, stabilization in the ICU may be required prior to surgical intervention.
  • In premature infants, consultation with a neonatologist may be required to manage associated diseases related to prematurity, such as hyaline membrane disease.
  • Consultation with a geneticist may be indicated if Turner syndrome or other genetic conditions are suspected.
  • Consultation with a nephrologist may be needed for assistance in treating patients with hypertension in preoperative or postoperative acute renal failure.
• Late presentation
• • Older patients may be initially referred to specialists prior to the diagnosis of CoA.
    • Referral to a hypertension clinic may lead to the diagnosis of CoA by the nephrologist.
    • Patients who undergo evaluation for suspected genetic syndromes may be referred to the cardiologist for evaluation because of previously undiagnosed coarctation.
  • Complications of CoA, such as intracranial hemorrhage or endocarditis, may require consultation with a neurosurgeon or infectious disease specialist, respectively.

Diet

• Persistent hypertension has been shown to increase the incidence of coronary artery disease (CAD); therefore, periodically examine patients who have undergone CoA repair for hypertension and recommend a healthy low-fat diet.
• Measure cholesterol levels and intervene pharmacologically in older patients as indicated, with a total cholesterol goal of less than 200 g/dL.
• Patients with persistent hypertension may require varying degrees of salt restriction.
• Emphasize dietary counseling and avoidance of obesity and smoking.

Activity

• Patients with CoA and hypertension who are awaiting surgical repair should limit heavy isometric exercises to a degree commensurate with the degree of hypertension.
• Generally, the duration of hypertension after CoA repair is related in part to the duration of hypertension prior to diagnosis and repair of coarctation. Patients who undergo repair of coarctation in infancy usually remain normotensive in the absence of significant residual arch obstruction and require no specific activity restrictions or limitations. With growth, coarctation may recur, and some patients may be normotensive at rest but have significant upper extremity hypertension provoked by exercise. Such patients who desire to participate in competitive athletics should undergo exercise stress testing prior to clearance.
• Patients who undergo repair later in life and who have had a significant period of preoperative hypertension are at particular risk for sustained postoperative hypertension, which may be permanent. Restrict heavy isometric exercise and other activities in these patients, commensurate with the degree of hypertension and BP control. Use exercise testing to assess BP response to exercise as a means of delineating reasonable exercise limitations.

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Drug Category: Prostaglandins

Alprostadil (PGE₁) promotes dilatation of the ductus arteriosus in infants with ductal-dependent cardiac abnormalities.

Drug Category: Inotropic agents

These agents are used to stimulate alpha- and beta-receptors in the heart and vascular bed. Positive inotropic agents increase the force of contraction of the myocardium and are used to treat acute and chronic CHF. Some may also increase or decrease the heart rate (ie, positive or negative chronotropic agents), provide vasodilatation, or improve myocardial relaxation. These additional properties influence the choice of drug for specific circumstances.

Drug Name	Dobutamine (Dobutrex)
Description	Produces vasodilation and increases the inotropic state. At higher doses, may cause increased heart rate, thereby exacerbating myocardial ischemia. Strong inotropic agent with minimal chronotropic effect and no vasoconstriction.
Adult Dose	0.5 mcg/kg/min IV initially; titrate until desired therapeutic effect attained; not to exceed 40 mcg/kg/min
Pediatric Dose	1-20 mcg/kg/min IV
Contraindications	Documented hypersensitivity; idiopathic hypertrophic subaortic stenosis; atrial fibrillation or flutter
Interactions	Beta-adrenergic blockers antagonize effects of dobutamine; general anesthetics may increase toxicity
Pregnancy	B - Usually safe but benefits must outweigh the risks.
Precautions	Caution following MI; hypovolemic state should be corrected prior to administration

Drug Category: Cardiac glycosides

These medications improve ventricular systolic function by increasing the calcium supply available for myocyte contraction.

Drug Category: Diuretic agents

These agents promote excretion of water and electrolytes by the kidneys. They are used to treat heart failure or hepatic, renal, or pulmonary disease when sodium and water retention have resulted in edema or ascites. Generally includes a loop diuretic that inhibits sodium chloride reabsorption in the ascending loop of Henle.