Atrial reservoir and active transport function after cardioversion of chronic atrial fibrillation.

Abstract

Atrial reservoir function has not been studied after successful cardioversion of chronic atrial fibrillation. Using transthoracic and transesophageal Doppler echocardiography, we measured flow velocity-time integrals of the systolic forward (Sa), diastolic forward (Da), and diastolic reversed (rAa) waves of flow velocity waveforms in the pulmonary vein and the superior vena cava, and those of the early diastolic (Ea) and late diastolic (Aa) waves of the transmitral and transtricuspid flow velocity waveforms. The left and right atrial storage fractions (LASF, RASF), indexes of atrial reservoir function, were determined as the ratios of the atrial storage volume to the ventricular stroke volume; (Sa - rAa)/(Sa - rAa + Da). The left and right atrial active contraction fractions (LAACF, RAACF), indexes of atrial active transport function, were also determined as the ratios of the atrial active contraction volume to the left ventricular stroke volume; Aa/(Ea + Aa). These indices were evaluated periodically in 12 patients with non-valvular chronic atrial fibrillation before and 1-4 days after direct current cardioversion of atrial fibrillation; in 8 of the patients, the indices were also evaluated 1-3 months after the cardioversion. An additional 10 patients in sinus rhythm served as controls. Both the LASF and RASF were low during atrial fibrillation; the values increased significantly 14 days after successful cardioversion (P < 0.01 P < 0.01), and continued to increase at 1-3 months. The LASF and RASF values 1-3 months after cardioversion were comparable to those in control subjects. Both the LAACF and RAACF also increased significantly from 1-4 days to 1-3 months after cardioversion (P < 0.05, P < 0.01), becoming comparable to those in control subjects. During the 3 months after successful cardioversion of non-valvular chronic atrial fibrillation, left and right atrial reservoir function and left and right atrial active transport function increased progressively, becoming comparable to values in the control subjects.