Atrioventricular Septal Defect

Complete atrioventricular septal defect with a large left-to-right shunt causes signs of heart failure Heart failure Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more (eg, tachypnea, dyspnea during feeding, poor weight gain, diaphoresis) by age 4 to 6 weeks. Pulmonary vascular obstructive disease (Eisenmenger syndrome Eisenmenger Syndrome Eisenmenger syndrome is a complication of uncorrected large intracardiac or aortic to pulmonary artery left-to-right shunts. Increased pulmonary resistance may develop over time, eventually... read more ) is usually a late complication but may occur earlier, especially in children with Down syndrome Down Syndrome (Trisomy 21) Down syndrome is an abnormality of chromosome 21 that can cause intellectual disability, microcephaly, short stature, and characteristic facies. Diagnosis is suggested by physical anomalies... read more .

Partial AV septal defects do not usually cause symptoms during childhood as long as left AV valve regurgitation is mild or absent. However, symptoms (eg, exercise intolerance, fatigue, palpitations) may develop during adolescence or early adulthood. Infants with moderate or severe left AV valve regurgitation often have signs of heart failure.

Patients with transitional AV septal defects may have signs of heart failure if the ventricular septal defect is moderately restrictive with high flow or may be asymptomatic if the ventricular septal defect is highly restrictive (small).

Physical examination in children with complete AV septal defects shows an active precordium due to volume and pressure overload of the right ventricle; a single, loud second heart sound (S2) due to pulmonary hypertension; a grade 2 to 3/6 systolic murmur due to increased flow across the pulmonary outflow tract; and sometimes a diastolic murmur at the apex and low left sternal border related to increased flow across the AV valves (see table ). In patients with persistent elevation of pulmonary vascular resistance, especially those with Down syndrome, there may be no murmur, but a loud single S2 will be present.

Most children with a partial defect have examination findings similar to patients with a secundum ASD Atrial Septal Defect (ASD) An atrial septal defect (ASD) is an opening in the interatrial septum, causing a left-to-right shunt and volume overload of the right atrium and right ventricle. Children are rarely symptomatic... read more , wide splitting of the S2 and a midsystolic (eg, ejection systolic) murmur audible at the upper left sternal border. A mid-diastolic murmur may be present at the lower left sternal border when the atrial shunt is large. A cleft in the left AV valve results in a blowing apical systolic murmur of mitral regurgitation.

Diagnosis of atrioventricular septal defects is suggested by clinical examination, supported by chest x-ray and ECG, and established by 2-dimensional echocardiography with color flow and Doppler studies.

Chest x-ray shows cardiomegaly with right atrial enlargement, biventricular enlargement, a prominent main pulmonary artery segment, and increased pulmonary vascular markings.

ECG shows a superiorly directed QRS axis (eg, left axis deviation or northwest axis), frequent first-degree AV block, left or right ventricular hypertrophy or both, and occasional right atrial enlargement and right bundle branch block.

Two-dimensional echocardiography with color flow and Doppler studies establishes the diagnosis and can provide important anatomic and hemodynamic information. Cardiac catheterization is not usually necessary unless hemodynamics must be further characterized before surgical repair (eg,, to assess pulmonary vascular resistance in a patient presenting at an older age).

Complete atrioventricular septal defect should be repaired by age 2 to 4 months because most infants have heart failure and failure to thrive. Even if infants are growing well without significant symptoms, repair should be done before 6 months to prevent development of pulmonary vascular disease, especially in infants with Down syndrome.

In patients with 2 adequately sized ventricles and no additional defects, the large central defect (combination of the primum ASD and inlet VSD) is closed and the common AV valve is reconstructed into 2 separate valves. Surgical mortality rate is 3 to 4% (1 Treatment reference Atrioventricular (AV) septal defect consists of an ostium primum type atrial septal defect and a common AV valve, with or without an associated inlet (AV septal type) ventricular septal defect... read more ).

Surgical complications include complete heart block (3%), residual ventricular septal defect, and/or left AV valve regurgitation. Less common residual abnormalities include right AV valve regurgitation, left or right AV valve stenosis, or subaortic stenosis.

Pulmonary artery banding may be used as a palliative procedure to delay the timing of open heart repair, particularly in preterm infants or those with associated abnormalities that make complete repair at an early age or low body weight higher risk.

For asymptomatic patients with a partial defect, elective surgery is done at age 1 to 3 years. Surgical mortality rate is very low.

The subset of patients with unbalanced AV septal defect, associated with either a hypoplastic right ventricle or hypoplastic left ventricle, generally are not amenable to a 2-ventricle repair and require operative staging toward a single ventricle circulation, ultimately with a Fontan procedure Treatment .

For patients with large shunts and heart failure Heart failure in neonates Congenital heart disease is the most common congenital anomaly, occurring in almost 1% of live births ( 1). Among birth defects, congenital heart disease is the leading cause of infant mortality... read more , diuretics, digoxin, and angiotensin-converting enzyme (ACE) inhibitors may help to manage symptoms before surgery.

Endocarditis prophylaxis Prevention Infective endocarditis is infection of the endocardium, usually with bacteria (commonly, streptococci or staphylococci) or fungi. It may cause fever, heart murmurs, petechiae, anemia, embolic... read more is not needed preoperatively and is required only for the first 6 months after repair or if there is a residual defect adjacent to a surgical patch.

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