Publications regarding shunt adjustments in PH-CHD patients are scarce and mostly limited to rather general consensus guidelines [
11,
12]. However, pre-interventional assessment of eligibility for intervention is mandatory, as shunt procedures contain a high risk of deteriorating RV overload in severe pulmonary hypertension. An irreversibly high PVR is generally considered a contraindication for shunt closure when a predominantly left-to-right shunt exists at rest [
2,
11,
13,
14]. This kind of shunt functions as a safety communication between the left and right heart through which systolic shunt reversal can occur during exercise, when systemic vascular resistance decreases in contrast to the fixed PVR. Closure of this type of shunt renders a decrease in RV afterload at rest. However, if the PVR remains high after closure, inability of shunt reversal during exercise can increase RV afterload and lead to progressive RV failure [
5]. In general, a PVR below 6 Wood units (WU) is thought to be feasible for shunt intervention. If the PVR exceeds this value but is less than two-thirds of the systemic resistance, intervention can still be considered. In line with this, the effective left-right shunt ratio (Qp:Qs) should be at least 1.5 in the case of a bidirectional shunt, as this inversely relates to the ratio between systemic and pulmonary vascular resistance [
2,
13‐
15]. RV dilatation, dysfunction and pulmonary regurgitation are other indications for intervention, although manifest RV failure inherently increases procedural risk [
13]. Furthermore, invasive corrections remain controversial after PVR reduction has been achieved using targeted therapy for pulmonary hypertension [
16‐
19]. When pulmonary hypertension persists after repair, the haemodynamic situation is comparable with idiopathic pulmonary arterial hypertension and the prognosis is deemed poor [
6].
Patients with PH-CHD exhibit great diversity and complexity in anatomic anomalies. The above-mentioned criteria illustrate that criteria to determine eligibility for intervention can be contradictory in individual cases. The current study states that refinement in individual disease characteristics, adjacent to relevant guidelines, is necessary to define appropriate treatment. To that purpose, we present four PH-CHD patients with worsening RV overload and an ambiguous indication for intervention. Shunt adjustments were performed by experts in the field after the local Grown-Ups with Congenital Heart Disease (GUCH) working group reached consensus regarding patient-tailored treatment.