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Pediatrics: Cardiac Disease and Critical Care Medicine > Cardiology
Atrial Septal Defect, Sinus Venosus
Article Last Updated: Aug 14, 2006
AUTHOR AND EDITOR INFORMATION
Section 1 of 11  
Author: Gary M Satou, MD, FACC, FAAP, Director of Pediatric Echocardiography, Section of Pediatric Cardiology, Mattel Children's Hospital at University of California at Los Angeles; Visiting Associate Professor, Department of Pediatrics, University of California at Los Angeles David Geffen School of Medicine
Gary M Satou is a member of the following medical societies: American Academy of Pediatrics, American College of Cardiology, American Heart Association, American Society of Echocardiography, and Society of Pediatric Echocardiography
Coauthor(s):
Jeff L Myers, MD, PhD Chief, Pediatric and Congenital Cardiac Surgery, Department of Surgery, Massachusetts General Hospital; Associate Professor of Surgery, Harvard Medical School;
James Jaggers, MD, Chief of Pediatric Cardiac Surgery, Professor, Department of Surgery, Division of Cardiovascular and Thoracic Surgery, Duke University Medical Center
Editors: Charles Berul, MD, Associate Professor of Pediatrics, Harvard Medical School; Senior Associate, Department of Cardiology, Children's Hospital of Boston; Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine.com, Inc; Alvin J Chin, MD, Professor of Pediatrics, Division of Cardiology, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine; Gilbert Herzberg, MD, Assistant Professor, Department of Pediatrics, Section of Pediatric Cardiology, New York Medical College; Steven R Neish, MD, SM, Director of Pediatric Cardiology Fellowship Program, Department of Pediatrics, Baylor College of Medicine
Author and Editor Disclosure
Synonyms and related keywords:
sinus venosus, atrial septal defect, ASD, superior vena cava type subcaval ASD, SVASD, atrial septum, congenital heart defect, congenital cardiac anomaly
Background
In simple terms, an atrial septal defect (ASD) is a deficiency of the atrial septum. ASDs account for about 10-15% of all congenital cardiac anomalies and are the most common congenital cardiac lesion presenting in adults. Sinus venosus ASDs account for only 10% of ASDs. The remaining ASDs are ostium secundum type (70%), ostium primum type (20%), and unroofed coronary sinus (coronary sinus septal defects) (<1%). Most children with sinus venosus ASD are asymptomatic, but may develop symptoms as they age. Excellent surgical results with a mortality rate near 0% can be expected. This is particularly true in patients who undergo repair when younger than 15 years. An ASD was the first lesion repaired using cardiopulmonary bypass in 1954 by John Gibbon, MD, at the Mayo Clinic.
Pathophysiology
The more common sinus venosus type defect (often referred to as the "usual type") occurs in the upper atrial septum and is contiguous with the superior vena cava (SVC). The lesion is rostral and posterior to the fossa ovalis (where secundum type defects occur) and is separate from it. It is almost always associated with anomalous pulmonary venous drainage of the right upper pulmonary vein into the SVC. Less commonly, the defect may occur at the junction of the right atrium and inferior vena cava (IVC) and be associated with anomalous connection of the right lower pulmonary vein to the IVC. Rarely, sinus venosus defects occur posterior to the fossa ovalis without bordering the SVC or IVC. The predominant hemodynamic consequence is a left-to-right shunt through the defect.
Frequency
United States
Sinus venosus defects represent approximately 1% of congenital cardiac lesions.
Mortality/Morbidity
- Treated: Surgical repair in the first 2 decades of life is associated with a mortality rate near zero. Life expectancy approaches that of the general population if the defect is repaired during this time. Cardiac size rapidly regresses after surgery, and the functional result is excellent. In cases of repair during adulthood, life expectancy may be decreased despite successful repair. Surgical morbidity rates are related to early postoperative pericardial effusion, early postoperative pulmonary venous or systemic venous obstruction, and supraventricular arrhythmias. If the baffle directing pulmonary venous blood to the left atrium is not placed correctly, it may obstruct pulmonary venous drainage. If the baffle bulges into the SVC, it may obstruct SVC inflow, necessitating the placement of an augmentation patch on the anterior surface of the SVC and right atrial junction.
- Untreated: Untreated ASDs are associated with a significantly shortened life expectancy. After age 20 years, the mortality rate is approximately 5% per decade with 90% of patients dead by age 60 years. These patients present with an increase in left-to-right shunting and occasionally with congestive heart failure with pulmonary hypertension in the fourth to sixth decades of life. Late problems in untreated patients also include the risk of paradoxical embolus as well as atrial fibrillation, pulmonary hypertension, and right heart failure.
Race
No racial predilection is known.
Sex
ASDs affect females more often than males. Female-to-male ratio is 2:1. No difference in outcome is associated with sex.
Age
Sinus venosus ASDs are congenital lesions present at birth. The age at presentation depends on the size of the left-to-right shunt. ASDs in infancy are usually asymptomatic. They are usually detected by echocardiography while undergoing a cardiac evaluation.
History
Sinus venosus ASDs, like most ASDs, are diagnosed upon detection of a murmur, a split second heart sound, and/or right heart enlargement on EKG in the usually asymptomatic patient.
- Symptoms of ASDs are typically a function of the size of the associated shunt.
- As many as 60% of apparently asymptomatic patients may have easy fatigability and dyspnea. Such symptoms usually indicate a relatively large shunt.
- Adults may not come to medical attention until symptoms occur. Arrhythmias, dyspnea, and a decrease in exercise tolerance are common symptoms.
Physical
- A cardiac murmur secondary to increased pulmonary artery blood flow is heard over the left sternal border. The murmur usually is a grade 2-3/6 systolic ejection murmur. A prominent right ventricular impulse may also be noted along the left sternal border. A diastolic flow murmur may be present at the left lower sternal border and the tricuspid area and is indicative of a large left-to-right shunt.
- The second heart sound is widely split and may be fixed or may vary little with respiration. The pulmonic component of the second heart sound is usually normal in intensity but may increase in intensity if pulmonary hypertension is present.
- Patients with ASDs may present with the "gracile habitus." These patients are thin for their height.
Causes
- During normal embryonic development, the right horn of the sinus venosus encompasses the right SVC and IVC. If there is abnormal resorption of the sinus venosus, an ASD results near the orifice of either the SVC or IVC.
- ASDs occur as associated anomalies in many major complex congenital lesions but sinus venosus ASDs occur more often as an isolated abnormality.
- Other abnormalities may exacerbate an ASD. For instance, systemic hypertension in an adult with a sinus venosus ASD may result in left ventricular hypertrophy and reduce left ventricular compliance, which in turn exacerbates the atrial level left-to-right shunt. Mitral stenosis, which is either congenital or acquired, may also exacerbate the atrial level left-to-right shunt.
Atrial Septal Defect, Coronary Sinus
Atrial Septal Defect, Ostium Primum
Atrial Septal Defect, Ostium Secundum
Atrioventricular Septal Defect, Partial and Intermediate
Cor Triatriatum
Partial Anomalous Pulmonary Venous Connection
Pulmonary Stenosis, Valvar
Lab Studies
- General laboratory studies rarely are helpful.
Imaging Studies
- Chest x-ray
- Prominent right atrium
- Prominent main pulmonary artery
- Increased heart size and pulmonary vascularity
- Echocardiography
- Echocardiography (ECHO) usually is sufficient for diagnosis in younger patients and is the diagnostic modality of choice.
- 2-Dimensional ECHO with color flow Doppler shows the position of the defect and the presence of anomalous pulmonary venous drainage and helps identify associated anomalies. It also documents left-to-right (or right-to-left) flow and right ventricular overload.
- ECHO effectively demonstrates the anomalous connection of the right pulmonary veins seen in more than 90% of patients with sinus venosus defects. In larger adolescent patients or adult patients, because of limited transthoracic echocardiographic windows, transesophageal echocardiography may be necessary to identify the atrial defect as well as the pulmonary venous drainage.
Other Tests
- Electrocardiogram
- Right ventricular hypertrophy predominates, with a lengthened PR interval and incomplete right bundle branch block (small rSR').
- P wave morphology may demonstrate atrial enlargement.
Procedures
- Cardiac catheterization usually is not required in the preoperative assessment of patients with sinus venosus ASD, but it may be considered in the following circumstances:
- In any child in whom associated lesions are suspected or in whom pulmonary hypertension is suspected, catheterization is performed to measure pulmonary artery pressure and, if pulmonary resistance is elevated, the response to pulmonary vasodilators.
- Adults who have the potential for associated coronary atherosclerotic lesions should undergo catheterization to exclude these abnormalities before surgical repair of the sinus venosus ASD.
Histologic Findings
Patients with pulmonary hypertension and advanced pulmonary vascular obstructive disease may exhibit histologic changes similar to those seen in pulmonary vascular disease. Specifically, these include intimal and medial hypertrophy and, in more advanced lesions, luminal occlusion.
Medical Care
- Medical care primarily is supportive and is not required for asymptomatic patients.
- Patients presenting in heart failure should be stabilized in anticipation of elective repair.
Surgical Care
Surgical correction is the mainstay of therapy.
- Repair of the SVASD is more complex than repair of the average secundum ASD. A patch (synthetic material or pericardium) is used to redirect blood flow from the right superior pulmonary vein into the left atrium. This effectively closes the interatrial communication while also correcting the anomalous pulmonary venous drainage. Sometimes, to avoid creating SVC obstruction, a patch is placed on the anterior surface of the SVC. Care is taken to avoid injuring the nearby sinus node. Ligation of the azygous vein also may be required to eliminate its drainage into the left atrium and to prevent the resulting residual right-to-left shunt.
- Asymptomatic children generally undergo repair when aged 3-5 years.
- Sinus venosus defects do not close spontaneously.
- Adults with left-to-right shunts greater than 1.5-2:1 benefit from surgical closure.
- Patients with significant pulmonary hypertension and elevated pulmonary vascular resistance unresponsive to pulmonary vasodilator therapy (eg, oxygen, nitric oxide, calcium channel blockers,) may not be good candidates for surgical repair. Such patients may develop acute right ventricular failure if their heart no longer has the ability to shunt right to left at the atrial communication in response to increases in pulmonary vascular resistance.
- Repair is performed most often through a standard median sternotomy. More cosmetic incisions may also be used, such as partial sternotomies, small right anterior thoracotomies, and inframammary incisions. All approaches still require the use of cardiopulmonary bypass for closure of the ASD.
- While transcatheter occlusion devices are currently used for closing secundum ASDs, such devices are not indicated (at present) for the closure of sinus venosus ASDs because of the position of the defect and because of the lack of surrounding tissue adequate to seat such an occlusion device. In addition, such a device might obstruct SVC flow and would not achieve redirection of the anomalous right pulmonary venous flow to the left atrium.
Consultations
- Pediatric cardiologist
- Pediatric cardiac surgeon
Diet
Activity
- Physical activity should not be limited in patients who undergo early and complete correction.
Medical management is ineffective in the treatment of sinus venosus defects. The rare patient who presents in congestive heart failure can be stabilized medically with diuretics and inotropic support.
Drug Category: Inotropic agents
These agents provide myocardial support in patients with dysfunction secondary to pulmonary overcirculation from left-to-right shunting. Positive inotropic agents increase the force of contraction of the myocardium and are used to treat acute and chronic CHF. Some also may 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 | Digoxin (Lanoxin) |
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| Description | Exerts its inotropic effects by increasing amount of intracellular calcium available during excitation-contraction coupling. One of numerous inotropic agents that can be used in infants with congenital cardiac defects. Generally used for long-term administration and is rarely drug of choice for acute management of heart failure in ICU setting. |
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| Adult Dose | Total digitalizing dose (TDD):
0.75-1.5 mg PO divided tid; 0.5-1 mg IV/IM divided tid
Divide TDD as follows: 50% initially; 25% 6-12 h later; 25% and the final 6-12 h later (one half, one quarter, one quarter)
Maintenance dose:
0.125-0.5 mg/d PO; 0.1-0.4 mg/d IV/IM |
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| Pediatric Dose | TDD:
Preterm neonate: 20-30 mcg/kg/d PO; 15-25 mcg/kg/d IV/IM
Term neonate: 25-35 mcg/kg/d PO; 20-30 mcg/kg IV/IM
1 month to 2 years: 35-60 mcg/kg/d PO; 30-50 mcg/kg/d IV/IM
2-5 years: 30-40 mcg/kg/d PO; 25-35 mcg/kg/d IV/IM
5-10 years: 20-35 mcg/kg/d PO; 15-30 mcg/kg/d IV/IM
>10 years: 10-15 mcg/kg/d PO; 8-12 mcg/kg/d IV/IM
Divide TDD as follows: 50% initially, 25% 6-12 h later; and the final 25% 6-12 h later (one half, one quarter, one quarter)
Maintenance dose:
Preterm neonate: 5-7.5 mcg/kg/d PO divided bid; 4-6 mcg/kg/d IV/IM divided bid
Term neonate: 6-10 mcg/kg/d PO divided bid; 5-8 mcg/kg/d IV/IM divided bid
1 month to 2 years: 10-15 mcg/kg/d PO divided bid; 7.5-12 mcg/kg/d IV/IM divided bid
2-5 years: 7.5-10 mcg/kg/d PO divided bid; 6-9 mcg/kg/d IV/IM divided bid
5-10 years: 5-10 mcg/kg/d PO divided bid; 4-8 mcg/kg/d IV/IM divided bid
>10 years: 2.5-5 mcg/kg/d PO; 2-3 mcg/kg/d IV/IM qd |
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| Contraindications | Documented hypersensitivity; digitalis-induced toxicity, AV block, idiopathic subaortic stenosis, constrictive pericarditis |
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| Interactions | Medications that may increase digoxin levels include alprazolam, benzodiazepines, bepridil, captopril, cyclosporine, propafenone, propantheline, quinidine, diltiazem, aminoglycosides, oral amiodarone, anticholinergics, diphenoxylate, erythromycin, felodipine, flecainide, hydroxychloroquine, itraconazole, nifedipine, omeprazole, quinine, ibuprofen, indomethacin, esmolol, tetracycline, tolbutamide, and verapamil
Medications that may decrease serum digoxin levels include aminoglutethimide, antihistamines, cholestyramine, neomycin, penicillamine, aminoglycosides, oral colestipol, hydantoins, hypoglycemic agents, antineoplastic treatment combinations (including carmustine, bleomycin, methotrexate, cytarabine, doxorubicin, cyclophosphamide, vincristine, procarbazine), aluminum or magnesium antacids, rifampin, sucralfate, sulfasalazine, barbiturates, kaolin/pectin, and aminosalicylic acid |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Hypokalemia may reduce positive inotropic effect of digitalis; IV calcium may produce arrhythmias in digitalized patients; hypercalcemia predisposes patient to digitalis toxicity, and hypocalcemia can make digoxin ineffective until serum calcium levels are normal; magnesium replacement therapy must be instituted in patients with hypomagnesemia to prevent digitalis toxicity; patients diagnosed with incomplete AV block may progress to complete block when treated with digoxin; exercise caution in hypothyroidism, hypoxia, and acute myocarditis |
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| Drug Name | Dopamine (Intropin) |
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| Description | Adrenergic agonists often are used for inotropic support in critical care setting for their rapid onset of action and rapid time to peak effect, which make them easier to titrate to effect |
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| Adult Dose | 1-20 mcg/kg/min continuous IV infusion; not to exceed 50 mcg/kg/min |
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| Pediatric Dose | Neonates: 1-20 mcg/kg/min continuous IV infusion
Infants and children: Administer as in adults |
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| Contraindications | Documented hypersensitivity; pheochromocytoma or ventricular fibrillation |
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| Interactions | Phenytoin, alpha- and beta-adrenergic blockers, general anesthesia, and MAOIs increase and prolong effects of dopamine |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Treat hypovolemia before infusion; administration through a central vein is recommended; do not use umbilical artery for infusion; if dosages >20 mcg/kg/min are required, consider a different agent (eg, epinephrine, dobutamine) |
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Drug Category: Loop diuretics
These agents are used for management of right heart failure and pulmonary edema. They promote excretion of water and electrolytes by the kidneys.
| Drug Name | Furosemide (Lasix) |
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| Description | Highly effective first-line diuretic in newborns and infants. A sulfonamide derivative, it exerts its effects on the loop of Henle and distal renal tubule, inhibiting reabsorption of sodium and chloride. |
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| Adult Dose | 10-200 mg PO/IV initially; titrate dose to effect; not to exceed 600 mg/d
Continuous IV infusions may be more successful; not to exceed 0.4 mg/kg/h |
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| Pediatric Dose | 1-2 mg/kg/dose PO/IV bid/qid; titrate dose to effect; not to exceed 6 mg/kg/dose bid/qid |
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| Contraindications | Documented hypersensitivity; hepatic coma, anuria, and state of severe electrolyte depletion |
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| Interactions | Metformin decreases furosemide concentrations; furosemide interferes with hypoglycemic effect of antidiabetic agents and antagonizes muscle relaxing effect of tubocurarine; auditory toxicity appears to be increased with coadministration of aminoglycosides and furosemide, hearing loss of varying degrees may occur; anticoagulant activity of warfarin may be enhanced when taken concurrently with this medication; increased plasma lithium levels and toxicity are possible when taken concurrently with this medication |
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| Pregnancy | C - Safety for use during pregnancy has not been established.
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| Precautions | Monitor serum potassium levels closely; may produce intravascular dehydration, severe hypokalemia, and significant hypochloremic metabolic acidosis; inform patients of potential for photosensitivity; may produce hyperuricemia; may produce deafness caused by ototoxicity; most popular strengths of digoxin and furosemide are white tablets of approximately equal size and may be confused by patients; administer oral dose with food or milk to decrease stomach upset |
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Further Inpatient Care
- Patients require a brief postoperative admission to a pediatric cardiac intensive care unit. The patient who undergoes uncomplicated surgical repair is usually discharged home within several days.
- Patients in heart failure may require short-term continued support until pulmonary edema resolves, myocardial function improves, and until pulmonary vascular resistance, if elevated, normalizes.
Further Outpatient Care
- Postoperative follow-up: This usually involves an office visit with the pediatric cardiologist (and possibly the cardiac surgeon) 1-3 weeks after hospital discharge.
- Echocardiography is used to effectively evaluate the repair for evidence of residual shunting, SVC or pulmonary vein obstruction, pericardial effusion, and ventricular function.
- The potential for late postoperative narrowing of the SVC does exist after repair of sinus venosus ASDs.
- Sinus node dysfunction screening should be part of outpatient follow-up care as sinus node dysfunction may become apparent years after repair of a sinus venosus ASD.
In/Out Patient Meds
- No long-term medication is required after repair of an uncomplicated ASD. Some surgeons prescribe aspirin or other anticoagulation regimens for a number of weeks for patients in whom a prosthetic patch was used to close the defect. This allows for endothelial ingrowth over the thrombogenic surface of the patch. Long-term anticoagulation is not indicated.
- Antibiotic prophylaxis is not required in patients who have had ASDs repaired.
Transfer
- Patients with a sinus venosus ASD should be transferred to a center experienced in the repair of such a defect in children or adults.
Complications
- Sinus node dysfunction
- Pulmonary venous obstruction
- Atrial fibrillation, atrial flutter, or SVT
- Pulmonary hypertension
- Atrial baffle leak
- Pericardial effusion or post-pericardiotomy syndrome
- SVC syndrome
Prognosis
- As discussed above, the prognosis is excellent for young patients who undergo repair of uncomplicated defects. Repair delayed until the third decade of life is associated with a decrease in life expectancy.
Patient Education
- Patient education mainly focuses on preoperative and postoperative care and recovery, which are especially important in young children undergoing surgery. Centers with experienced child life personnel are invaluable in preparing children for open-heart surgery.
Medical/Legal Pitfalls
- Failure to consider ASD in infants and children diagnosed with failure to thrive may lead to a missed diagnosis. A delay in diagnosis of an ASD until the third decade of life is associated with decreased life expectancy.
| Media file 1:
Panel A. Transesophageal echocardiogram (transverse view) of a patient with a sinus venosus defect of the superior vena cava (SVC) type. The original defect (white star burst) has been repaired by placing a baffle (arrows), which directs blood from the anomalously connected right upper pulmonary vein into the left atrium (LA). In this patient, the baffle was redundant so at a more rostral level (Panel B), it could be seen (black open arrows) to bulge into the superior vena cava (SVC)–right atrial (RA) junction (trio of white arrows). The remainder of the atrial septum is denoted by the duo of white open arrows. Panel C is a transesophageal echocardiogram, sagittal view. Doppler color flow mapping verifies that the protruding baffle (white closed arrows) results in a narrowing of the pathway from the SVC to the RA. The quartet of white open arrows points to the remainder of the atrial septum. |
 |  View Full Size Image | |
Media type: CT
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| Media file 2:
Panel A is a transesophageal echocardiogram, transverse view. The white star burst shows the sinus venosus defect of the inferior vena cava (IVC) type, lying adjacent to the IVC junction with the right atrium (RA). The remainder of the atrial septum is just out of the view of this sector but is represented by the white open arrowheads. The leaflets of the closed tricuspid valve (TV) are visible. RV = right ventricle. Panel B is a transesophageal echocardiogram, sagittal view. This is the same patient as in Panel A. This view proves that the rostral portion of the atrial septum (which would be missing in a patient with a sinus venosus defect of the SVC type) is intact. ct = crista terminalis; svc = superior vena cava. |
 | View Full Size Image | |
Media type: Photo
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Atrial Septal Defect, Sinus Venosus excerpt Article Last Updated: Aug 14, 2006
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