Rethinking Operability in Large VSD: The Diastolic Pulmonary Shunt Index (DiPSI) and a Probabilistic Perspective

Assessing operability in late-presenting ventricular septal defects (VSD) with pulmonary arterial hypertension (PAH) is complex. Although a comprehensive assessment is often recommended, pulmonary vascular resistance index (PVRI) is the cornerstone of most decisions. PVRI-based operability assessment, nonetheless, is not infallible. Cases with PVRI much higher than operability cut-offs have done well, while some with lower PVRI have experienced late recurrence of PAH. We propose the Diastolic Pulmonary Shunt Index (DiPSI), defined as the diastolic pulmonary gradient (DPG = PADP - PAWP) divided by Qp/Qs, as an adjunct to aid clinical judgment. DiPSI, by offering a physiologically grounded, flow-adjusted index, may help clarify borderline cases, providing a more nuanced assessment of operability in late presenters with large VSD than PVRI alone.