Microvascular reactivity in rehabilitating cardiac patients based on measurements of retinal blood vessel diameters

Abstract

Background:Exercise-based rehabilitation improves general cardiovascularfitness. The impact on the micro-vascular system has been studied in less detail. We measured changes in retinal blood vessel diameters, as aproxy for microvascular reactivity, in cardiac patients and we assessed the impact of a rehabilitation program onretinal vessel diameters.Design:Cardiac patients (n = 78) and age-matched healthy controls (n = 32) performed an initial maximalendurance cycling test. Patients then participated in a 12-week rehabilitation program with additional en-durance tests being performed six and twelve weeks after the initial test.Methods:Fundus images were collected immediately before and 0, 5, 10, 15 and 30 min after the endurance test.Widths of retinal blood vessels, represented as Central Retinal Arteriolar/Venular Equivalent (CRAE/CRVE) werecalculated from the images.Results:At the start of the rehabilitation program, CRAE and CRVE values of the patients changed immediatelyafter the endurance test with respectively−1.90μm (95% CI:−3.58;−0.22) and−5.32μm (95% CI:−7.33;−3.30) compared to baseline values. In contrast, CRAE and CRVE values of healthy controls were respectivelyincreased [3.52μm (95% CI: 2.34; 4.69)] and decreased [−3.17μm (95% CI:−5.27;−1.07)]. After six andtwelve weeks, CRAE responses of patients immediately after endurance test increased respectively with 5.98μm(95% CI: 4.25; 7.71) and 4.44μm (95% CI: 3.18; 5.71). These responses were similar to the microvascularreactions observed in the control group.Conclusions:Arteriolar and venular retinal microvascular responses in cardiac patients were different from theones of healthy controls. Retinal microvascular response of cardiac patients improved during rehabilitation