First-in-Human Experience of Mechanical Preload Control in Patients With HFpEF During Exercise

Abstract

Exercise intolerance remains one of the major factors determining quality of life in heart failure patients. In 6 patients with heart failure with preserved ejection fraction (HFpEF) undergoing invasive cardiopulmonary exercise testing, balloon inflation within the inferior vena cava (IVC) was performed during exercise to reduce and maintain pulmonary arterial (PA) pressures. Partial IVC occlusion significantly reduced PA pressures without reducing cardiac output. Partial IVC occlusion significantly reduced respiratory rate at matched levels of exercise. These findings highlight the importance of pulmonary pressures in the pathophysiology of HFpEF and suggest that therapies targeting hemodynamics may improve symptoms and exercise capacity in these patients.

Keywords: CPET, cardiopulmonary exercise testing; HFpEF, heart failure with preserved ejection fraction; IVC occlusion; IVC, inferior vena cava; LV, left ventricle/ventricular; PA, pulmonary artery; PCWP, pulmonary capillary wedge pressure; VCO2, carbon dioxide consumption; VO2, oxygen consumption; cardiac output; heart failure; hemodynamics.

Graphical abstract

Figure 1

Fluoroscopic Image of Partial IVC Balloon Occlusion Fluoroscopic image of partial balloon inflation within the inferior vena cava (IVC) to control pulmonary pressures. The occlusion balloon was advanced from the right internal jugular vein so that the legs were free to cycle unencumbered.

Figure 2

Invasive Cardiopulmonary Testing Data: Control Versus Partial IVC Occlusion Trajectories of oxygen consumption (VO₂), minute ventilation (VE), carbon dioxide consumption (VCO₂), pulmonary artery (PA) systolic pressure, right atrial pressure, and respiratory rate with and without partial inferior vena cava balloon occlusion during each exercise phase.

Figure 3

Detailed Data in Selected Patients During Invasive Cardiopulmonary Testing Trajectories of VE-to-VCO₂ ratio (VE/VCO₂), cardiac output, and PA diastolic pressure at each stage of exercise in 5 of 6 subjects with optimal left ventricular (LV) filling pressures (left). The same trajectories in the 1 subject in whom overinflation reduced LV filling and a reduction in cardiac output (right). IVC = inferior vena cava; other abbreviations as in Figure 2.

Figure 4

Theoretical Effect of Partial IVC Occlusion to Reduce External Restraint and Paradoxically Improve Left Ventricular Stroke Volume Theoretical relationship between LV filling pressures and stroke volume in heart failure subjects. The effective transmural distending pressure is the measured LV pressure minus external forces, typically the pericardial restraint (P_tm = P_measured – P_ext). Partial IVC occlusion may reduce pericardial restraint and paradoxically increase the transmural pressure and subsequently the cardiac output, despite reducing the measured LV pressure. Abbreviations as in Figure 3.