PV Loop and Pulmonary Hypertension

The right ventricular (RV) systolic function is a key determinant of outcome in patients with pulmonary hypertension and elevated pulmonary vascular resistance. As the pulmonary artery pressure and vascular resistance increase (i.e. RV afterload) in these patients, so does the right ventricular contractility in an attempt to maintain cardiac output. This is response of a ventricle to its afterload is termed ventriculo-arterial (VA) coupling. However, there is a limit to this increase in contractility after which VA uncoupling occurs ultimately leading to decrease cardiac output and right ventricular failure. The accepted gold standard for measurement of VA coupling is the ratio of the end systolic ventricular elastance (Ees) to the end systolic arterial elastance (Ea) measured invasively via high fidelity conductance catheters during cardiac catheterization. In this study, the aim is to devise a non-invasive scoring system that can identify VA uncoupling in patients with elevated pulmonary vascular resistance using echocardiography, cardiac MRI, cardiopulmonary exercise testing and brain natriuretic peptide levels. The hypothesis is that a group of morphologic and functional variables obtained noninvasively can differentiate an RV with VA coupling from that with VA uncoupling.