The Baroreflex Control of Heart Rate is Impaired in Patients with Peripheral Arterial Disease

Abstract

Prior reports suggest that exercise pressor reflex is heightened in peripheral arterial disease (PAD). It is unclear if PAD alters the baroreflex. We hypothesized that the sensitivity of baroreflex (BRS) control of heart rate (HR) in PAD patients would be lower than that in healthy control subjects. We studied 12 PAD patients (8 M, 4 F, 66 ± 2 yrs), and 10 healthy control subjects (7 M, 3 F, 65 ± 2 yrs). The ankle‐brachial pressure index in the most affected leg in the patients was 0.64 ± 0.03. ECG and beat‐by‐beat blood pressure (BP, Finometer) were recorded for 10 min under resting condition. Thereafter, the subjects performed rhythmic plantar flexion with incremental loading (2–12 kg, +1 kg/min) until the subject reached fatigue or exercised for a maximum of 14 min. The PAD patients performed the exercise with the most affected leg. The cardiac BRS was estimated with the sequence technique. The HR variability (HRV) indices were also calculated. Under resting conditions, cardiac BRS in PAD patents was significantly lower than that in the control subjects (5.5 ± 0.7 vs. 12.0 ± 2.3 ms/mmHg, P=0.008). The resting time domain HRV in PAD patents was also lower than in healthy subjects. Plantar flexion exercise induced BP response was greater at end exercise in PAD patients than that in healthy control subjects. Interestingly, plantar flexion exercise tended to decrease cardiac BRS in healthy subjects, whereas it tended to increase cardiac BRS in PAD patients. The plantar flexion exercise decreased the time domain HRV index (last 5 min) in the both groups. We speculate that the decreased cardiac BRS as well as the attenuated vagal tone (i.e. lower HRV) indicate that autonomic function is impaired in PAD. Further studies are needed to examine if exercise training in PAD alters the baroreflex function.Support or Funding InformationSupported by National Institutes of Health Grants P01 HL134609 (Sinoway), UL1 TR002014 (Sinoway), and Pennsylvania Department of Health Tobacco CURE Funds SAP#4100079742 (Cui).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.