Effect of warm-Up exercise studied with wave intensity analysis

The effect of warm-up on myocardial perfusion in patients with coronary artery disease (CAD) is not well understood. Coronary wave intensity reflects the effects of cardiac contraction and relaxation on coronary blood flow dynamics. It can distinguish between left ventricular (forward, FW) and microcirculatory (backward, BW) originating contributions. Our aim was to establish whether coronary wave intensity analysis can help to elucidate the underlying mechanism. In this study, we compared the effect of repeat exercise periods on coronary hemodynamics and wave intensity in 11 patients with CAD. Aortic pressure, distal coronary pressure (Pd) and flow velocity (U) were recorded while the patients performed two consecutive periods of supine bicycle exercise (Ex1, Ex2). Wave intensity was calculated as (dPd/dt)(dU/dt) and the separate BW and FW contributions were derived. Patients reached similar exercise levels in Ex1 and Ex2 but with less symptoms of cardiac ischemia in Ex2. The energy of the dominant waves increased with exercise duration. Waves occurring during the coronary filling phase were enhanced at repeat exercise. Changes in cardiac-coronary interaction could hence contribute to the warm-up effect.