Alterations in cardiac function immediately following electrical conversion of atrial fibrillation to normal sinus rhythm.

SUMMARY An assessment was made of cardiac function by means of right heart catheterization before and immediately after conversion of atrial fibrillation to sinus rhythm in 11 studies on 10 human subjects. Comparable data during exercise were available in five studies. Medical management of patients in this study was identical to that employed routinely for this procedure. After conversion to normal sinus rhythm cardiac output response was significantly increased only during exercise. The relationship of mean right atrial and mean pulmonary wedge pressures to right and left ventricular stroke work was uniformly improved both because of decreases in these pressures and increases in work. Indirect evidence of mitral valvular regurgitation was diminished to absent after conversion. "'A" waves and the pulse pressure of atrial contraction were very small in the right atrial tracings after conversion and these contours were usually inapparent on pulmonary wedge tracings. It is concluded that overall cardiac performance was improved with re-establishment of sinus rhythm and that diminutions in atrial-venous pressure behind each ventricle may be important in explaining symptomatic improvement following electroconversion. Measures of both pressure and flow were required for complete description of the alterations induced by this intervention.