Coronary Blood Flow Regulation is Impaired During Exercise in Patients with Peripheral Arterial Disease

Abstract

Peripheral arterial disease (PAD) is associated with an augmented blood pressure response while walking, impaired vascular function, and increased risk of myocardial infarction. We hypothesized that coronary exercise hyperemia is impaired in PAD. Seven PAD patients (67± 2 yrs) and 11 healthy controls (64 ± 2 yrs) performed dynamic plantar flexion exercise at progressive workloads (0.5 ‐ 7.0 kg) with their most symptomatic leg. Coronary blood flow velocity (CBV) in the left anterior descending artery was measured by transthoracic Doppler echocardiography and blood pressure and heart rate were monitored continuously. Rate Pressure Product (RPP) and the myocardial O2 supply/demand ratio (CBV/RPP *1000) were calculated. Since PAD patients exercised for a shorter duration, data were compared at the 2.0 kg workload, which all subjects performed with minimal pain. The change in RPP from rest to exercise at 2.0 kg was augmented in PAD patients vs. controls (2417 ± 489 vs. 1026 ± 143 mmHg*bpm, P = 0.01). The change in the myocardial O2 supply/demand ratio from rest to exercise was impaired in PAD patients vs. controls (2.94 ± 0.99 vs. 5.17 ± 1.35 au, P = 0.05). These data suggest that coronary hyperemia is inadequate for the large rise in myocardial metabolism during low intensity exercise in PAD, which may increase risk for adverse cardiovascular events.