Evaluation of the Pulmonary Vascular Reactivity Test in Patients With Pulmonary Arterial Hypertension and a Cardiac Shunt

Pulmonary arterial hypertension (PAH) is an important cause of mortality and morbidity in patients with congenital heart disease with a shunt. These congenital cardiac shunts are responsible for PAH, which evolves towards higher pulmonary vascular resistance if they are not closed early. Patients with significant pulmonary flow and low pulmonary vascular resistance fully benefit from surgical shunt closure with complete disappearance of pulmonary hypertension after closure. In contrast, patients with low pulmonary flow and high pulmonary vascular resistance will have no benefit because they keep a deleterious pulmonary hypertension after closure of the shunt. In certain situations, especially late discovery of heart disease, the issue of operability of these patients is crucial because closing the shunt inappropriately worsens the spontaneous prognosis. Currently, in case of doubt on the operability, there are several clinical and hemodynamic criteria used empirically, but their predictive value is uncertain. It is therefore necessary to stratify patients into operable and inoperable groups to improve their overall outcome after surgery. In this research project we propose to assess the predictive performance of the pulmonary vascular reactivity to acetylcholine test on the presence of elevated PAH 1 year after the closure of the shunt. This reactivity test will be evaluated on a population of patients for whom the decision of the surgical closure of the shunt has been adjudicated on the basis of explorations and usual tests (and therefore blind to the knowledge of the result of the reactivity test). The test in this study is designed with repeated injections and increasing doses with a continuous flow of acetylcholine in the left lower lobe of the pulmonary artery. The last injection consisted with adenosine with inhaled O2/NO (potentiating effect) for maximum vasodilatation. The parameter of interest is the Doppler flow velocity in the pulmonary artery endothelium-dependent vasodilation by acetylcholine relative to the speed at maximum vasodilatation (adenosine + in nitric oxide (NO) inhalation)