Pulmonary vasodilator-induced haemodynamic decline and recovery post-discontinuation in two single-ventricle cases.

Pulmonary vasodilators increased the systemic-to-pulmonary collateral flow in two single-ventricle cases, causing haemodynamic decline. Discontinuation reversed the collateral flow and improved heart failure, highlighting the need for careful monitoring. Serial cardiac MRI, as a non-invasive tool, may be essential to detect changes in collateral flow and guide vasodilator use for optimal management in this population.