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Key Concepts

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  • Epidemiology

    • The prevalence of atrioventricular septal defect (AVSD) is 0.19 per 1000 live births, accounting for 2.9 percent of congenital cardiac malformations. In about 60 percent of these cases, shunting is confined to the atrial level. Tetralogy of Fallot (ToF) is associated in 2 to 10 percent of cases of AVSD, while Down syndrome is seen in 75 percent of infants with complete AVSD.

  • Morphology

    • This is variable, according to extent and presence of atrial and ventricular components; however, a common atrioventricular valve (AV) and displacement of the AV node are common features. These defects typically fall into three categories: (A) partial (primum component only); (B) complete atrial septal defect (ASD) and ventricular septal defect (VSD); and (C) transitional (restrictive VSD). Complete AVSD is further subdivided according to the degree of bridging of the superior leaflet. Although Rastelli type A is most common (70 percent of all complete AVSDs), type C is the one most frequently associated with ToF.

  • Pathophysiology

    • Pathophysiology varies with the degree of shunting, left ventricular AV valve regurgitation, and pulmonary vascular resistance, as well as with associated anomalies.

  • Clinical features

    • Larger left-to-right shunts (complete AVSDs) will present early in infancy with congestive heart failure and pulmonary hypertension, while presentation of partial and transitional AVSDs (in the absence of significant left AV valve regurgitation) will present later and have a similar presentation and natural history as ASDs.

  • Diagnosis

    • Chest x-ray (CXR) will disclose an enlarged cardiac silhouette and increased pulmonary markings in large shunts. Echocardiography is diagnostic and defines type of defect, valvar morphology and degree of regurgitation, relative ventricular balance, and associated anomalies. Cardiac catheterization is used in selected cases and shows the characteristic “gooseneck deformity” from subaortic elongation of the left ventricular outflow tract (LVOT).

  • Treatment

    • A staged approach [pulmonary artery banding (PAB) followed by complete repair] is relegated to selected cases of complete AVSD. Most cases should be repaired before 6 months of age, whereas partial defects without valvar regurgitation and defects with a restrictive VSD component can be repaired between 2 and 4 years of age.

  • Outcomes

    • Operative mortality for complete AVSDs is currently below 5 percent, and incomplete defects have similar morbidity and mortality as ASDs. Long-term prognosis is defined by long-term valvar completenvy and associated lesions.

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Introduction

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Following the first successful repair of atrioventricular septal defects (AVSDs) at the dawn of modern cardiac surgery, significant advances have been made in many aspects of overall patient management. In line with improvements in cardiopulmonary bypass, postoperative care, and refinement of surgical technique together with morphologic understanding,1 there has been a striking reduction in both postoperative mortality and early morbidity.

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Reflecting this increased confidence in the operative management in the last quarter century,2 there has been an evolution in the timing of surgery from a staged approach to an era of complete repair in early infancy (Fig. 66-1).1,3...

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