AUTHOR AND EDITOR INFORMATION

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• Follow-up
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INTRODUCTION

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Background

In this article, single ventricle is anatomically defined as a heart that is missing the smooth (ie, nontrabeculated) inflow region of either ventricle. Most cases of tricuspid atresia and mitral atresia retain at least a remnant of this smooth septal aspect of the right ventricle (RV) or left ventricle (LV), respectively. Thus, the atrioventricular connection in single ventricle is either double-inlet (2 or more atrioventricular orifices) or common-inlet (common atrioventricular orifice). With a better understanding of cardiovascular morphogenesis, the morphologic RV and morphologic LV may eventually be defined with molecular markers. Currently, the most reliable antemortem method of identifying single ventricle is with 2-dimensional echocardiography.

Much of the surgical literature over the last 30 years uses a functional definition; namely, that single ventricle is present when 1 of the 2 ventricles is small enough that a series circuit (systemic venous return to ventricle 1 to pulmonary arteries to pulmonary venous return to ventricle 2 to systemic arteries) is incompatible with survival.

Until the early 1970s, surgical management did not include separating the pulmonary and systemic circulations. Modifications of the procedure initially proposed in 1971 by Fontan for tricuspid atresia have been widely adopted in the last 2 decades.¹ These cavopulmonary or atriopulmonary modifications effectively channel the systemic venous blood directly into the pulmonary arteries. Whether the effect on overall quality of life is superior to that of the more limited palliations used before 1971 is still unclear. Hepatic dysfunction, protein-losing enteropathy, and, most ominously, disadvantageous ejection efficiency combined with elevated afterload characterize Fontan-type circulation.

Single LV is a relatively uncommon disorder in which the RV is rudimentary and consists of only an arterial outflow. The single LV communicates with the rudimentary RV via a bulboventricular foramen (outlet foramen). The rarely observed single RV occurs when no discernible LV is present. Both atria connect to the single ventricle via either a common atrioventricular valve (sometimes termed the common-inlet ventricle) or separate atrioventricular valves (double-inlet ventricle). Single ventricle most frequently occurs with transposition, but any ventriculoarterial alignment can be seen. Subpulmonary stenosis is more prevalent than the combination of aortic arch obstruction and subaortic stenosis. Although rare, single ventricle can occur without stenosis of either pulmonary or aortic outflow.

The embryology of single ventricle is still unknown. Presumably, both ventricular septation and movement of the common atrioventricular orifice are disrupted. In fact, many genetic alterations can likely result in a single ventricle phenotype. Five single-gene targeted disruptions in mice (Nkx2.5, Isl1, Mef2c, Hand2, and fog-2) have already been reported to result in single ventricle prenatally. The fog-2 null mouse also displays a common atrioventricular orifice situated almost entirely over the future LV.

Pathophysiology

No circulatory derangement is observed in fetal development because pulmonary circulation and systemic circulation are normally in parallel, with 2 levels of connection: atrial and ductal. However, lack of separation between pulmonary and systemic circulations causes obvious cyanosis postnatally, with severity dependent on the degree of coexistent subpulmonary stenosis. Although cases of single ventricle and arch obstruction are the least cyanotic because they never display subpulmonary stenosis, such patients are vulnerable to poor lower body perfusion upon reduction in ductal diameter.

Frequency

United States

Single ventricle occurs in approximately 5 of every 100,000 live births.

Mortality/Morbidity

The severity and timing of presentation depend on the extent of coexistent subpulmonary stenosis (or, alternatively, aortic obstruction) and on reduction in caliber of the ductus arteriosus.

Sex

No disparities are known.

Age

Presentation is generally within the first month of life. As the ductus arteriosus reduces in caliber within the first few days of life, those infants with severe subpulmonary stenosis or aortic obstruction present with cyanosis or poor peripheral perfusion, respectively.

CLINICAL

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History

• Neonates with single ventricle and subpulmonary stenosis become cyanotic but are usually without other symptoms.
• Neonates with single ventricle and aortic obstruction may have rapid breathing, lethargy, and poor feeding.

Physical

• Cyanosis is present in patients with subpulmonary stenosis.
• Poor peripheral perfusion is evident in patients with single ventricle with aortic obstruction.
• If aortic obstruction involves coarctation or interruption, then a difference in blood pressure is observed between the right arm and a lower extremity, unless the right subclavian artery is aberrant. 
• The first heart sound is normal.
• The second heart sound is single.
• A systolic ejection murmur is present in those with subpulmonary stenosis as well as those with aortic obstruction.

Causes

• The cause of single ventricle is unknown.
• So far, 5 targeted single-gene disruptions in mice have produced a right ventricular (RV) hypoplasia phenotype reminiscent of single left ventricle (LV). These disruptions include global nulls in Nkx2.5, Isl1, Mef2c, dHand (also known as Hand2), and fog-2. The fog-2 null also displays a common atrioventricular orifice situated almost entirely over the future LV. Whether hypomorphic alleles of the homologous mutations in the human produce a single ventricle phenotype but do not result in embryonic lethality remains to be shown.
• The myocardial-specific inactivation of GATA4 also causes single ventricle.

DIFFERENTIALS

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Other Problems to be Considered

Pulmonary stenosis or complex heart malformation with pulmonary stenosis as a component

Arch obstruction or complex heart malformation with aortic stenosis, arch obstruction, or both as a component

Neonatal sepsis

WORKUP

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Lab Studies

• No specific laboratory blood tests are required in the workup for single ventricle.
• An ABG measurement is frequently helpful in distinguishing between cases of single ventricle with subpulmonary stenosis and those cases of single ventricle with arch obstruction, aortic stenosis, or both. For example, when prostaglandin E₁ has not been administered, a PaO₂ of greater than 50 mm Hg lessens the likelihood that a newborn with single ventricle has significant subpulmonary stenosis. However, this PaO₂ is perfectly consistent with the presence of arch obstruction.
• Following Fontan operation, albumin and total protein levels are helpful in surveillance for protein-losing enteropathy, which is a known complication. Fecal alpha1-antitrypsin helps prove that the hypoproteinemia is at least partly due to excessive intestinal loss. Prolongation in the prothrombin time (a measure of hepatic synthetic function) and a reduction in alkaline phosphatase levels (largely a reflection of osteoblastic activity in children) are early clues to hepatic dysfunction and protein-losing enteropathy, respectively.

Imaging Studies

• Two-dimensional echocardiography and Doppler analysis
• • Two-dimensional echocardiography is diagnostic for single ventricle. The presence or absence of subpulmonary stenosis, arch obstruction, and aortic stenosis can also be determined. The particular atrioventricular connection and ventriculoarterial alignment is also revealed in a straightforward manner.
  • The 2 most common forms of single ventricle are L-looped single left ventricle (LV) with transposition of the great arteries and subpulmonary stenosis and D-looped single LV with transposition of the great arteries and subpulmonary stenosis. The third most common form is L-looped single LV with transposition of the great arteries and aortic arch hypoplasia.
  • In single LV with transposition of the great arteries and aortic arch obstruction, the aortic stenosis that frequently coexists is due to a narrowing at the communication between the LV and the rudimentary right ventricle (RV). This orifice is frequently referred to as a bulboventricular foramen or outlet foramen.
• Echocardiography prior to initial surgery
• • Initial identification of single ventricle
  • Presence or absence of subpulmonary stenosis
  • Presence or absence of arch obstruction
  • Presence or absence of narrowing of communication between normal-sized ventricle and rudimentary ventricle
  • Presence or absence of atrioventricular valve regurgitation, which would have to be palliated prior to Fontan operation
  • Presence or absence of pulmonary artery distortion
  • Ventricular performance
• Echocardiography prior to hemi-Fontan (or bidirectional Glenn) operation
• • Presence or absence of pulmonary artery distortion, either congenital or created inadvertently by prior pulmonary artery surgery
  • Presence or absence of second superior vena cava
  • Ventricular performance
• Echocardiography prior to Fontan operation (whether lateral tunnel or extracardiac conduit)
• • Determination of whether a pulmonary arteriovenous malformation has developed
  • Presence or absence of pulmonary artery distortion, either congenital or created inadvertently by prior pulmonary artery surgery 
  • Ventricular performance
• Echocardiography after Fontan operation
• • Characterization of the fenestration, in cases in which a fenestrated Fontan solution is adopted
  • Presence or absence of effusions, pericardial or pleural, or ascites
  • Presence or absence of thrombus formation
  • Presence or absence of pulmonary venous pathway obstruction
  • Ventricular performance
    
• Chest radiography
• • Chest radiography findings vary.
  • In cases with pulmonary stenosis, the cardiac silhouette is normal to mildly enlarged. Pulmonary vascularity is not increased.
  • In cases with arch obstruction, the cardiac silhouette is usually at least mildly enlarged. Pulmonary vascularity usually is increased.
• Radionuclide imaging: Lung perfusion scans can be helpful in roughly quantifying left-right asymmetry of blood flow after hemi-Fontan or Fontan operation.

Other Tests

• Electrocardiography: Common findings include septal q wave in the right precordial leads (in cases of L-looped single LV) and a monotonous R/S pattern over the anterior precordium.
• Holter monitoring: This is useful after a hemi-Fontan operation (or bidirectional Glenn operation) and is particularly helpful after a Fontan operation for surveillance of supraventricular arrhythmias, including sinus bradycardia and atrial flutter.
• Cardiac MRI
• • Anatomy - Static, steady-state free precession (SSFP) bright blood images; double-inversion, dark blood images; half-Fourier acquisition single-shot turbo spin-echo (HASTE) sequences 
  • Physiology - Stack of cines (short axis of ventricle, to analyze ventricular performance), cines of systemic venous pathway and pulmonary arteries 
  • Velocity mapping of superior vena cava, inferior vena cava, branch pulmonary arteries, and aorta
  • Post–gadolinium injection, 3-dimensional reconstruction, and viability imaging

Procedures

• Cardiac catheterization is largely reserved for evaluating candidacy for Fontan operation, characterizing post-Fontan hemodynamics, and managing supraventricular arrhythmic complications.
• Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.
• Complications may include rupture of blood vessel, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.

TREATMENT

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Medical Care

• Evaluation as an inpatient in an intensive care setting is advised.
• Intravenous prostaglandin E₁ is indicated in patients with severe arch obstruction and is frequently indicated in patients with subpulmonary stenosis.
• The need for introduction of an arterial line and assisted ventilation can be judged best from the initial ABG measurement.

Surgical Care

• Because the pulmonary vascular resistance gradually falls over the first few months of life, conversion to a cavopulmonary or atriopulmonary circulation cannot be safely accomplished in the first few days of life.
• If subpulmonary stenosis is present, its severity dictates whether a systemic-to-pulmonary artery shunt is needed after ductal closure. If aortic arch obstruction is present instead, the most widely adopted approach is to reestablish unobstructed aortic arch flow and to limit pulmonary blood flow.
• • As a way of limiting pulmonary blood flow, banding of the pulmonary artery has given way to other methods because most patients with arch obstruction have a narrow bulboventricular foramen
  • Although it may not be initially restrictive, the bulboventricular foramen tends to reduce in diameter over time and may precipitously reduce in caliber following volume-unloading procedures, including pulmonary artery banding (as well as the hemi-Fontan and Fontan operations).
  • To avoid the possibility of hemodynamically important aortic stenosis, a Norwood-type reconstruction (proximal pulmonary artery–to–aorta anastomosis) is currently favored. Enlarging the bulboventricular foramen by resection of muscle is hazardous because of the proximity of the conduction system and the frequent presence of atrioventricular valve attachments to the rim.
• Creation of a cavopulmonary circulation is more safely accomplished in stages over 1-2 years because acute volume unloading is associated with an acute increase in ventricular wall thickness. This wall thickness increase markedly alters the diastolic performance of the single ventricle and can limit cardiac output. The hemi-Fontan procedure results in less severe wall thickness changes than the full Fontan procedure.
• • The less-than-complete Fontan is currently viewed as the most favorable balance of nearly normal arterial oxygen saturation and the lowest frequency of effusive complications. Thus, even the so-called "final" stage commonly takes the form of a fenestrated Fontan, in which virtually all of the vena caval blood is routed to the pulmonary arteries.
  • A solitary hole 4-5 mm in diameter or multiple holes 2-3 mm in diameter are placed in whatever structure separates the systemic venous pathway from the pulmonary venous pathway. In the latter style, eventual spontaneous closure is the rule; however, some of these patients subsequently develop protein-losing enteropathy and return for surgical creation of a stable fenestration 5 mm in diameter.
  • An alternative less-than-complete Fontan involves partial hepatic vein exclusion. One hepatic vein, typically the left anterior hepatic vein, can be excluded from the systemic venous pathway when the baffle is placed. This excluded hepatic vein drains into the pulmonary venous pathway. Unfortunately, most patients with partial hepatic vein exclusion eventually return with right hepatic vein–to–left hepatic vein collaterals.
• Cardiac transplantation is considered for patients who have undergone the Fontan operation and have developed serious complications and for patients whose hemodynamics make them poor candidates for Fontan operation.

Consultations

• Cardiologist
• Cardiothoracic surgeon

Diet

No special diet is required.

Activity

• No restrictions are needed if coexistent subaortic (and/or aortic) hypoplasia has been successfully relieved.
• The resting cardiac index of patients prior to the Fontan operation is about 80% of normal. Also, a limited ability to increase cardiac output typically results in decreased exercise capacity.

MEDICATION

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Preoperatively, administer alprostadil (ie, IV prostaglandin E₁). Postoperatively, warfarin is largely protective against venous thrombosis. Angiotensin-converting enzyme inhibitors, although popularly utilized, have not been shown to improve resting or exercise cardiac index.

Drug Category: Prostaglandins

Alprostadil (PGE1) is used for treatment of ductal-dependent cyanotic congenital heart disease, which is due to decreased pulmonary blood flow.

Drug Category: Anticoagulants

These agents prevent recurrent or ongoing thromboembolic occlusion.

Drug Category: Angiotensin-converting enzyme (ACE) inhibitors

The pharmacologic effects result in a decrease in systemic vascular resistance, reducing blood pressure, preload, and afterload.

FOLLOW-UP

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Further Inpatient Care

• Admit for testing and surgical intervention

Further Outpatient Care

• Following each stage of surgical reconstruction, echocardiographic and Doppler evaluation of hemodynamic adequacy should be performed.
• After the Fontan operation, annual visits should be arranged to survey for hepatic dysfunction, supraventricular arrhythmias, and protein-losing enteropathy.
• Should effusive complications, which are common in the early period after a Fontan procedure, recur months or years later, a comprehensive search for a surgically correctable cause should be undertaken. Examples of such correctable etiologies are late-onset pulmonary venous obstruction and thrombosis of the left pulmonary artery.
• Only after mechanical obstructions are ruled out should a classic protein-losing enteropathy workup be initiated.

In/Out Patient Meds

• The treatment of postoperative patients with supraventricular arrhythmias, such as atrial flutter, is frequently complex because many patients who have undergone a Fontan operation have sinus node dysfunction and can only be safely administered antiarrhythmic agents if a pacemaker is placed first.
• Various approaches are being empirically tried for patients who have undergone a Fontan operation. These include the following:
• • No medications
  • Furosemide, with or without additional diuretics
  • Angiotensin-converting enzyme (ACE) inhibitor
  • Digoxin
  • Warfarin for the first 3 months after fenestrated Fontan
  • Combinations of the above medications

Transfer

• Transfer may be required for further diagnostic evaluation and surgical intervention.

Complications

• Pleural effusions, pericardial effusions, ascites
• • Long considered the most agonizing early postoperative complication, thoracic and abdominal effusions persisted for weeks and often impaired cardiac output. In the early 1990s, these complications threatened to preclude the application of Fontan's principle to the vast majority of patients with single ventricle.
  • Although the molecular and cellular basis of this complication remains a mystery, surgeons have begun using the less-than-complete Fontan operation as their final stage. The partial hepatic vein exclusion variation used by Lecompte and then by Norwood has largely been abandoned because more than 80% of patients developed intrahepatic venous collaterals that resulted in increasing right-to-left shunts.
  • Hence, the less-than-complete Fontan operation most widely used in the late 1990s is the fenestrated Fontan operation proposed by Laks. Effusive complications are greatly reduced following the fenestrated Fontan. However, arterial oxygen saturation is usually in the high 80s or low 90s, rather than the mid 90s seen after nonfenestrated Fontan.
• Atrial flutter
• • This is the most prevalent of the numerous late complications following the various modifications of the Fontan operation and may be the heralding sign of hemodynamic deterioration. The basis for this complication is still unknown, although its treatment can be complex because of the frequent coexistence of sinus node dysfunction.
  • Current hypotheses for the etiology of the sinus node dysfunction center on surgical trauma to portions of the sinus node region or its blood supply.
  • As an alternative to the hemi-Fontan operation, use of the so-called bidirectional Glenn operation, followed subsequently by extracardiac conduit (rather than the lateral tunnel) placement, has failed to reduce the frequency of sinus node dysfunction. This may be because the demarcation of the sinus node region is not macroscopically evident; thus, attempts to avoid it (such as the bidirectional Glenn) may have been unsuccessful.
  • Because the onset of atrial flutter episodes is frequently preceded, if not invariably preceded, by months or years of atrial bradycardia, prophylactic atrial pacing may possibly postpone the emergence of atrial flutter. Because of the technical challenges of atrial pacing in infants, this proposal has not yet been the subject of a randomized clinical trial.
• Thromboembolism
• • Venous, but not arterial, thrombosis occurs in nearly 10% of survivors of the fenestrated Fontan operation. The cause of this complication is unknown. Sites can include the pulmonary arteries and the cerebral veins. Subnormal cardiac output, subnormal intracardiac pulsatility of blood flow, and altered hepatic production of components of endogenous thrombolytic pathways have all been proposed as possible etiologies. Hepatic dysfunction, as measured by prothrombin time and galactose elimination half-life, is the rule.
  • Thrombi have been observed in both the pulmonary venous side of the "lateral tunnel" baffle and the systemic venous side. The presence of a fenestration allows thrombi in the systemic venous circulation to gain access to the systemic arterial circulation.
  • Aspirin is often prescribed as prophylaxis for venous thrombosis following fenestrated Fontan in infancy, but it appears to be ineffective in this setting.
• Protein-losing enteropathy
• • Manifesting as diarrhea, poor appetite, and growth failure, protein-losing enteropathy occurs in at least 10% of long-term survivors of nonfenestrated Fontan procedures.
  • The cause of this usually devastating complication is unknown, although fenestration creation appears to be a successful palliation. Atrial pacing has succeeded in at least 2 cases.² Other proposed remedies, including steroids and heparin, have succeeded in individual cases but have more numerous adverse effects such as osteopenia. Reduction of both CD4+ and CD8+ T lymphocytes is observed; disproportionate reduction of the CD4+ subset results in a reversal of the CD4+/CD8+ ratio. Immunoglobulin G (IgG) levels and, to a lesser extent, immunoglobulin A (IgA) levels are diminished.
  • Not observed in the pre-1980 era (when Fontan-type operations were rarely performed), protein-losing enteropathy is thus a result of surgically created cavopulmonary/atriopulmonary circulatory arrangements and is not merely a result of being born with a single ventricle heart.
• Persistent discrete or long-segment narrowing of the left pulmonary artery
• • In the program of staged surgery to reach a fenestrated Fontan, distortions of the left pulmonary artery are frequently difficult to entirely abolish, even at the time of the final stage.
  • The importance of identifying cases of Fontan-to-one-lung circulation lies in their vulnerability to the hemodynamic consequences of ipsilateral pulmonary insults. Fifty percent of patients with Fontan-to-one-lung circulation develop protein-losing enteropathy, arguing strongly that protein-losing enteropathy is a sequela of Fontan hemodynamics.
• Formation of venous collaterals and varices
• • Patients with single ventricle and the coexistence of interrupted inferior vena cava still have hepatic venous blood that drains to the pulmonary venous side of the circulation after a Kawashima variation of the Fontan procedure.
  • Collaterals can occasionally form, allowing venous blood from the upper part of the body to eventually reach the pulmonary venous side of the circulation in this subset of patients with single ventricle, as well as in others.
  • The increased right-to-left shunt can be identified by monitoring either pulse oximetry or hemoglobin levels. 
  • Bronchial wall varices have been observed, possibly due to high superior vena cava pressure.
  • Esophageal varices occur in patients with hepatic dysfunction and portal hypertension.
• Low exercise capacity
• • Although individual exceptions have been observed, the exercise capacity of patients who survive the Fontan procedure, even those with fenestrated variants, is subnormal.
  • The resting cardiac index is about 80% of normal. Disadvantageous ejection efficiency is present, combined with elevated pulsatile and nonpulsatile components of ventricular afterload.
• Growth failure
• • This is observed in patients who survive the Fontan operation even in the absence of documented protein-losing enteropathy.
  • The molecular and cellular basis of this complication is unknown.
  • Whether exogenous growth hormone ameliorates the subnormal growth (but with acceptable incidence of adverse effects) is not known.
• Formation of pulmonary arteriovenous malformations
• • This complication of the hemi-Fontan operation and its variants appears to resolve after the performance of a less-than-complete Fontan operation (of the lateral tunnel, extracardiac conduit, or hepatic vein exclusion varieties).
  • Contrast echocardiography appears to be a highly sensitive method of identifying pulmonary arteriovenous malformations.
• Plastic bronchitis: This is characterized by the development of mucinous bronchial casts.
• Formation of systemic-to-pulmonary arterial collaterals
• • This complication of the hemi-Fontan operation and its variants usually resolves after performing a less-than-complete Fontan (of either the lateral tunnel, extracardiac conduit, or hepatic vein exclusion varieties).
  • The mechanism that underlies collateral formation may be hypoxia-induced upregulation of vascular endothelial growth factor (VEGF). A hypoxia-response element has been identified within the VEGF promoter.

Prognosis

• The prognosis is fair, unless atrial flutter, a cerebrovascular accident, or protein-losing enteropathy occur. More than one half of patients should survive 20 years. Patients with even moderate atrioventricular valve regurgitation have a demonstrably poorer outcome.

Patient Education

• Because the outcome of various modifications of Fontan operation includes a monotonically increasing prevalence of serious sequelae, discussion with families about prognoses are necessarily lengthy.
• If the initial identification of single ventricle is made in utero, then the possibility of pregnancy termination may also be introduced to family members.
• Finally, the family should confront the possibility that cardiac transplantation may eventually be needed, even if the staged approach to achieve a fenestrated Fontan is the initial strategy adopted.

MISCELLANEOUS

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Medical/Legal Pitfalls

• Failure to recognize symptoms and signs of coexistent arch obstruction
• Failure to recognize inadequately relieved subaortic stenosis, aortic stenosis, or both

Special Concerns

• Although treatments for single ventricle (which, as stated earlier in this article, does not include the entity of hypoplastic left heart syndrome) have been refined over the last 30 years, they have not convincingly improved upon the limited palliations offered before 1971. Because of this, extra caution is advised in the initial discussions with the family.
• • Unlike hypoplastic left heart syndrome, in which the staged approach to reach a cavopulmonary circulation is clearly superior to performing only the first stage (Norwood procedure), the vast majority of patients with single ventricle have a morphologic left ventricle (LV), do not present in extremis, and are relatively stable over many years once initial palliation, including a systemic–to–pulmonary arterial shunt, is completed and a pulmonary/systemic flow ratio of between 1.5 and 2.0 is achieved.
  • Whether the cavopulmonary circulation matches or surpasses this quality of life over a 30-year period is still an open question. The long-term effect of a mean systemic venous pressure greater than 10 mm Hg is unknown in the pediatric population.

MULTIMEDIA

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Media file 1:  Cranially angulated frontal angiogram of an L-looped single left ventricle. Abbreviations are as follows: ao=aorta, mpa=main pulmonary artery, oc=outlet chamber (rudimentary right ventricle).
	View Full Size Image
Media type:  Angiogram

Media file 2:  Long axial oblique-equivalent subcostal echocardiogram of single left ventricle (vent) with narrow communication (unlabeled arrow) between left ventricle and outlet chamber (oc). Abbreviations are as follows: L=left, lav=left atrioventricular valve, P=posterior, rav=right atrioventricular valve, S=superior.
	View Full Size Image
Media type:  Echo

Media file 3:  Pulsed Doppler echocardiographic evaluation of the narrowing shown in Media file 2. On the left, the sample volume (split oval) is placed just distal to the narrow area. On the right, spectral analysis reveals a mixture of velocities, consistent with the presence of highly nonlaminar (turbulent) flow.
	View Full Size Image
Media type:  Echo

Media file 4:  Schematic diagram of a lateral tunnel Fontan. Although the example shown is from a double-outlet right ventricle with left ventricular hypoplasia, it shows the same intra-atrial reconstruction as would be done in a single, common-inlet, right ventricle with bilateral superior venae cavae. Blood from the venae cavae is routed directly to the pulmonary arteries. Pulmonary venous blood flows through the common atrioventricular valve into the right ventricle. Abbreviations are as follows: IVC=inferior vena cava, HV=hepatic vein, LPA=left pulmonary artery, LPVs=left pulmonary veins, LSVC=left superior vena cava, RPA=right pulmonary artery, RPVs=right pulmonary veins, RSVC=right superior vena cava, RV=right ventricle.
	View Full Size Image
Media type:  Image

Media file 5:  Volume-unloading operations, such as the hemi-Fontan procedure, result in increases in wall thickness, as shown by subcostal echocardiography. Frontal views are seen in sections A, B, C and D. Sagittal views are seen in sections E, F, G and H. Pre–hemi-Fontan views are seen in A, B, E, and F. Post–hemi-Fontan views are seen in C, D, G, and H. End-diastole views are seen in A, C, E, and G. End-systole views are seen on B, D, F, and H. In all panels, a pair of open triangles point to markers 1 cm apart.
	View Full Size Image
Media type:  Echo

Media file 6:  Cardiac MRI. Frontal view of a 3-dimensional flow field in a patient who has undergone a lateral tunnel type of modified Fontan operation (A). This surgical palliation for patients with only one functional ventricle redirects venous blood from the superior vena cava (SVC) and inferior vena cava (IVC) directly into the right (RPA) and left (LPA) pulmonary arteries. Flow streamlines are shown in red. B. Frontal view of in plane velocity mapping. Right (R jug) and left (L jug) jugular vein flow towards the feet is signal-poor (black). Flow toward the head in the infrahepatic inferior vena cava (IVC) and intracardiac portion of the systemic venous pathway (svp) is signal-intense (white). Images courtesy of Dr. Mark A. Fogel, The Children's Hospital of Philadelphia.
	View Full Size Image
Media type:  MRI

REFERENCES

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1. Fontan F, Mounicot FB, Baudet E, et al. ["Correction" of tricuspid atresia. 2 cases "corrected" using a new surgical technic]. Ann Chir Thorac Cardiovasc. Jan 1971;10(1):39-47. [Medline].
2. Cohen MI, Rhodes LA, Wernovsky G, Gaynor JW, Spray TL, Rychik J. Atrial pacing: an alternative treatment for protein-losing enteropathy after the Fontan operation. J Thorac Cardiovasc Surg. Mar 2001;121(3):582-3. [Medline].
3. Barber BJ, Burch GH, Tripple D, Balaji S. Resolution of plastic bronchitis with atrial pacing in a patient with fontan physiology. Pediatr Cardiol. Jan-Feb 2004;25(1):73-6. [Medline].
4. Bromberg BI, Schuessler RB, Gandhi SK, et al. A canine model of atrial flutter following the intra-atrial lateral tunnel Fontan operation. J Electrocardiol. 1998;30 Suppl:85-93. [Medline].
5. Bull K. The Fontan procedure: lessons from the past. Heart. Mar 1998;79(3):213-4. [Medline].
6. Cai CL, Liang X, Shi Y, Chu PH, Pfaff SL, Chen J. Isl1 identifies a cardiac progenitor population that proliferates prior to differentiation and contributes a majority of cells to the heart. Dev Cell. Dec 2003;5(6):877-89. [Medline].
7. Canobbio MM, Mair DD, van der Velde M, Koos BJ. Pregnancy outcomes after the Fontan repair. J Am Coll Cardiol. Sep 1996;28(3):763-7. [Medline].
8. Chang RK, Alejos JC, Atkinson D, et al. Bubble contrast echocardiography in detecting pulmonary arteriovenous shunting in children with univentricular heart after cavopulmonary anastomosis. J Am Coll Cardiol. Jun 1999;33(7):2052-8. [Medline].
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Article Last Updated: Oct 3, 2007