Isolated Ventricular Septal Defect

Abstract

Isolated ventricular septal defect (VSD) is the most common congenital anomaly at birth. The presentation of unrepaired VSDs is largely dependent on the presence of hemodynamically significant shunt; hence it is directly related to the size of the defect. Small VSDs only lead to the minimal left-to-right shunt without left ventricular fluid overload or pulmonary arterial hypertension (PAH); they are usually asymptomatic or found incidentally on physical examination. Medium size VSDs result in a moderate left ventricular volume overload and absent to mild PAH; they present late in childhood with mild congestive heart failure. Those with large defects develop congestive heart failure early in childhood due to the severe left ventricular overload and severe PAH. Small defects are expected to close spontaneously in the first year of life; however, larger defects can result in severe complications. In the setting of long-standing large left-to-right shunts, the pulmonary vascular endothelium undergoes irreversible changes resulting in persistent PAH. When the pressure in the pulmonary circulation exceeds the pressure in the systemic circulation, the shunt direction reverses and becomes a right-to-left shunt. This is known as Eisenmenger syndrome, and it occurs in 10-15% of patients with VSD. Surgical VSD closure is the standard of care with device closure emerging as a promising alternative. This chapter will focus on the classification and pathophysiology of isolated VSD, with detailed information on the operative approach and further discussion on newer interventions to repair isolated VSD.