Ambulatory cardiac rehabilitation improves pulsatile arterial hemodynamics: a pilot trial

The Role of Arterial Stiffness and Central Hemodynamics in Heart Failure

Whereas traditional understanding of left ventricular afterload was focused on a steady-state circulation model with continuous pressures and flow, a more realistic concept is emerging, taking the pulsatile nature of the heart and the arterial system into account. The most simple measure of pulsatility is brachial pulse pressure, representing the pulsatility fluctuating around the mean blood pressure level. Brachial pulse pressure is widely available, fundamentally associated with the development and treatment of heart failure (HF), but its analysis is often confounded in patients with established HF. The next step of analysis consists of arterial stiffness, central (rather than brachial) pressures, and of wave reflections. The latter are closely related to left ventricular late systolic afterload, ventricular remodeling, diastolic dysfunction, exercise capacity, and, in the long term, the risk of new-onset HF. Wave reflection may also evolve as a suitable therapeutic target for HF with preserved and reduced ejection fraction. A full understanding of ventricular-arterial coupling, however, requires dedicated analysis of time-resolved pressure and flow signals. This review provides a summary of current understanding of pulsatile hemodynamics in HF.

Pulsatile Hemodynamics Are Associated With Exercise Capacity in Patients With Exertional Dyspnea and Preserved Left Ventricular Ejection Fraction

BACKGROUND

Pulsatile hemodynamics are associated with left ventricular filling pressures and diastolic dysfunction. We investigated their relationship with maximum workload and peak oxygen uptake (peak VO2) in patients with exertional dyspnea and preserved left ventricular ejection fraction (LVEF).

METHODS

Radial waveforms from tonometry were processed with a transfer function, pulse wave analysis and wave separation analysis, yielding central aortic pressures and measures of forward (amplitude of forward wave-Pf) and reflected waves (augmentation index-AIx, augmentation pressure-AP, amplitude of backward wave-Pb) and their ratio (reflection magnitude). Aortic pulse wave velocity (aoPWV) was estimated with a validated formula from single-point waveforms. Ergospirometry for assessment of exercise capacity was performed on a bicycle ergometer, using a ramp protocol.

RESULTS

Sixty-six patients were included (43 females; mean age 66 years; 83% hypertensives; mean body mass index 28.3 kg/m2). Mean peak VO2 was 17.0 ml/min/kg, mean achieved maximum workload 104.5 watts (80.9% of a reference population). Maximum workload and peak VO2 showed significant inverse relationships with AIx, AP, Pb, and aoPWV (r = -0.26 to -0.57). In multiple adjusted regression models, brachial and aortic pulse pressure, AP, Pf, Pb, and aoPWV were significant independent predictors of maximum workload, whereas AP, AIx75, Pf, Pb, and aoPWV were independently related to peak VO2.

CONCLUSIONS

Pulsatile hemodynamics are independently associated with objective measures of exercise capacity in patients with normal LVEF.