Alteration of peripheral vasodilatory reserve capacity after cardioversion of atrial fibrillation

Abstract

In atrial fibrillation, exercise capacity is often reduced. This is usually ascribed to a decreased cardiac output as compared with sinus rhythm. Very few studies, however, have focused on changes in the peripheral blood flow during atrial fibrillation as a potential mechanism for exercise limitation. The aim of the present study was to determine the effect of conversion of atrial fibrillation to sinus rhythm on peripheral blood flow. Calf blood flow, using an electrocardiogram-triggered venous occlusion plethysmograph, and peak oxygen consumption (peak VO2), using treadmill exercise testing, were studied in 28 patients with chronic atrial fibrillation eligible for electrical cardioversion. Measurements were performed before cardioversion, and repeated 1 day and 1 month thereafter. Calf blood flow at rest, maximal calf blood flow, and minimal calf vascular resistance during the hyperaemic response immediately following 700 J of calf exercise were determined plethysmographically. One day and 1 month after cardioversion, 23 and 14 patients were still in sinus rhythm, respectively. In patients who still had sinus rhythm after 1 month, maximal calf blood flow increased from 33.7 +/- 12 to 40.0 +/- 13 ml. 100 ml-1.min-1 (P < 0.01) and minimal calf vascular resistance fell from 3.2 +/- 0.9 to 2.7 +/- 0.7 mmHg. ml-1. 100 ml-1. min-1 (P < 0.01); peak VO2 increased from 21.3 +/- 4 to 24.2 +/- 5 ml. min-1. kg-1 (P < 0.001). Calf blood flow at rest did not improve. In contrast, no significant changes in maximal calf blood flow, minimal calf vascular resistance and peak VO2 occurred in patients who had atrial fibrillation 1 month after cardioversion. A significant correlation was found between changes in maximal calf blood flow and peak VO2 1 month after cardioversion (r = 0.53, P < 0.01). One day after cardioversion, no changes in calf blood flow or peak VO2 were found, either in patients with sinus rhythm or atrial fibrillation. In conclusion, transition from chronic atrial fibrillation to sinus rhythm is associated with a (delayed) improvement in maximal calf blood flow, minimal calf vascular resistance, and peak VO2. Our findings suggest that increase in vasodilatory reserve capacity may contribute to the improvement of exercise capacity after cardioversion of atrial fibrillation.

Impact of Atrial Fibrillation on Exercise Capacity in Heart Failure With Preserved Ejection Fraction

“…Additionally, since peak VO 2 represents the product of cardiac output and arterial-venous oxygen content difference, a greater impairment of peripheral oxygen availability or utilization in AF may also be important. Endothelial dysfunction 40 and peripheral muscle blood flow abnormalities have been correlated with exercise performance in patients with chronic AF, although in the absence of structural heart disease 41 .…”

Exercise hyperventilation, dyspnea sensation, and ergoreflex activation in lone atrial fibrillation

“…A contribution of peripheral changes resulting from this arrhythmia to the pathogenesis of exercise intolerance is undefined, although there are good reasons to believe that this is a possibility. In fact, the intermittent peripheral blood flow dynamics might affect the shear stress flow-mediated vascular control, impair the blood flow redestribution to exercising muscles (13,35), and sustain changes in muscle myofibrillar energetics (25). An irregular ventricular activity as induced by atrial fibrillation leads to a significant increase of the sympathetic outflow, which is responsible for an abnormal reflexogenic cardiovascular control and neural imbalance (37).…”

Restoration of sinus rhythm does not improve peripheral blood flow in hemodynamically stable patients with atrial fibrillation

“…In the performed analyses we demonstrated that the values of the plethysmographic indices during AFib in comparison to the values obtained after restoring sinus rhythm did not differ significantly. Amongst available literature, there is a limited number of studies discussing the plethysmographic assessment of peripheral flow in patients with AFib [5][6][7][8]. What is more, only small groups of patients were examined and the main aim of these investigations was the assessment of vasodilatation reserve and analysis of the function of endothelium in patients with arrhythmia and after restoring sinus rhythm.…”

“…Gosselin and co-authors [5] analyzed blood flow through the calf during rest and after exercise in 28 patients with chronic AFib, with repeat measurements performed after restoring sinus rhythm. As their investigative method, they have used straingauge plethysmography, in which the inflation and deflation of the cuff that temporarily cut off the circulation were performed within 5 to 6 heartbeats.…”

“…Although there have been many studies on the effects of AFib on cardiac function, very few have focused on changes in peripheral blood flow during arrhythmia [5][6][7][8]. Therefore, the aim of our study was to assess peripheral blood flow during AFib and after restoring sinus rhythm.…”