The role of exercise central hemodynamics for the clinical classification of heart failure patients

Abstract

Central hemodynamic evaluation during exercise testing provides critical information for the clinical classification of reduced (HFrEF) or preserved ejection fraction (HFpEF) heart failure (HF) patients. Recent and encouraging observations suggest that non-traditional indices of central hemodynamics can robustly describe cardiac function and pulmonary vascular hemodynamics in healthy individuals and in HF. Therefore, because of emerging evidence in favor of non-traditional indices to describe central hemodynamics in HF, it is unclear what index or indices best describe cardiac function and the heart-lung hemodynamic interaction in HF. Moreover, contributing to the complexity of the pathophysiology underlying the HF syndrome, it is becoming more recognized that neural mechanisms originating within skeletal muscle likely contribute to impaired cardiovascular function and symptoms of these patients. However, it remains unclear what role this neural feedback from skeletal muscle ergoreceptors has in the impaired central hemodynamic response frequently observed during exercise in HF. Therefore, the aims of this dissertation focused on investigating factors to better understand the central hemodynamic response to exercise in HF. In this series of studies we observed that non-traditional measurement of cardiac and pulmonary hemodynamics could describe the central hemodynamic response to exercise in HF. Also, experimental manipulation of neural feedback from skeletal muscle ergoreceptors resulted in observations which suggest pulmonary hemodynamics could be influenced by this mechanism, whereas cardiac function may not be similarly influenced by this pathway in HFrEF. Equally important and relevant to both clinical and research settings, it was observed that non-invasive measurement of stroke volume at peak exercise could be reliably estimated using echocardiography, acetylene rebreathe, and oxygen pulse in HF.