The pulmonary vascular resistance is not significantly elevated and the left-to-right shunt is small (Qp:Qs <1.5:1). 2. Large nonrestrictive defects in cyanotic patients who have developed Eisenmenger syndrome, with pulmonary vascular resistance at systemic levels and shunt reversal (right-to-left). 3. Patients with moderately restrictive defects (Qp:Qs 1.5:1 and <2:1) who have not undergone clo- sure for some reason. These patients often have mild-to-moderate PAH. 4. Patients who have had their defects closed in childhood. These patients may have VSD patch leaks.See Section 3.3 for recommendations on who should perform surgeries, cardiac catheter- ization, and other procedures in these patients; Section 3.4 for recommendations on diagnostic evaluation; Section 4.4.6 for evaluation and management of severe PAH and Eisenmenger syndrome; Figure 2 for a diagnostic and treatment algorithm for ventricular level shunt; and Table 14 for routine testing and follow-up intervals. Recommendation-Specific Supportive Text 1. In the absence of aortic valve prolapse and regur- gitation or IE, small restrictive defects of the mus- cular or membranous septum may be watched conservatively without need for operative inter- vention. In a long-term follow-up registry, the overall survival rate was 87% for all patients with unoperated VSD at 25 years.S4.1.3-1 For patients with small defects (Qp:Qs <1.5:1 and low PA pressure), the survival rate was 96%. Patients with moderate and large defects fared worse with 25-year sur- vival of 86% and 61%, respectively. Those with Eisenmenger syndrome (cyanosis/hypoxemia caused by reversal of shunt to right-to-left) had a Figure 2. Hemodynamically significant ventricular level shunt. *Combination therapy with bosentan and PDE-5 inhibitor, if symptomatic improvement does not occur with either alone. 