Mechanisms of Right Ventricular Adaptation in Patients With Heart Failure With Preserved Ejection Fraction

The right ventricle is the main determinant of prognosis in pulmonary hypertension . The response of the right ventricle to the structural alterations and increasing afterload in the pulmonary circulation is a complex process. The interplay between neuroendocrine and paracrine signalling and increased afterload may lead to myocardial ischemia and inflammation, resulting in loss of myocytes, myocardial fibrosis and RV-arterial uncoupling. Pulmonary hypertension in the setting of heart failure with preserved ejection fraction (HFpEF-PH) is a frequent complication which is associated with impaired prognosis. HFpEF-PH is defined by a high mean pulmonary artery pressure (\> 20 mm Hg), high left ventricular end-diastolic pressure (LVEDP \> 15 mm Hg) and a normal systolic left ventricular function with impaired diastolic function. However, not all HFpEF patients develop pulmonary vascular remodelling with a high transpulmonary pressure gradient, and increased pulmonary vascular resistance leading to adverse right ventricular remodelling. Ageing, increased left atrial pressure and stiffness, mitral regurgitation, as well as features of metabolic syndrome, including obesity, diabetes and hypertension, are recognized as clinical risk factors for HFpEF-PH. A main and emerging question in that context is the interplay between the right and left ventricle in HFpEF-PH, and whether diastolic left ventricular failure is the driving force of the hemodynamic and right ventricular functional changes. Recent studies have shown that HFpEF-PH patients demonstrate haemodynamic limitations during exercise, including impaired recruitment of LV preload due to excessive right heart congestion and blunted RV systolic reserve compared to HFpEF without PH . However, up to now, no data exist about the mechanism of interplay between RV, LV and pulmonary haemodynamics in HFpEF and HFpEF-PH. Whereas in patients with HFpEF, PV loop analysis has demonstrated that increased end-diastolic pressure at rest is associated with higher end-diastolic stiffness, and a consistently upwards and leftwards shifted pressure volume relationship during exercise and volume challenge, Gortner et al suggest that reduced LV preload (measured by LV transmural pressure gradient) due to excessive RV congestion, is a major driver for reduced cardiac output in HFpEF-PH. However, preliminary own data in 21 patients with HFpEF demonstrate a more complex relationship with approximately one third of patients not showing an increase of (RV and LV ) end-diastolic pressure volume relation during exercise. Thus, a simultaneous PV loop-catheterization of LV and RV, in addition to right heart catheter, would therefore provide an enormous gain of knowledge about the interaction of RV and LV and would contribute to a better understanding of the pathophysiology of HFpEF-PH and HFpEF.