Assessment of left atrial transport function immediately after cardioversion

Abstract

Left atrial transport function was evaluated immediately after cardioversion in 10 patients by altering the timing of left atrial and ventricular contraction using right ventricular pacing. The effect of abruptly withdrawing the left atrial contribution to ventricular filling by suddenly decreasing the P-R interval from optimal to zero was evaluated by measuring left ventricular ejection time and peak systolic and systolic mean blood pressure. In 8 patients, a decrease in left ventricular ejection time (282 to 253 msec, P < 0.001); peak systolic (126 to 117 mm Hg, P < 0.001) and systolic mean (107 to 97 mm Hg, P < 0.001) blood pressure confirmed the presence of left atrial transport function. In this group, pre- and postcardioversion cardiac output determinations showed no significant difference (4.21 to 4.01 liters/mm, P > 0.4). In 2 patients, left ventricular ejection time remained unchanged, indicating absence of left atrial transport function. One of the 2 patients demonstrated left atrial transport function on reevaluation 14 days later.The deleterious effect of an inappropriately timed left atrial contraction on left ventricular ejection time, peak systolic blood pressure and systolic mean blood pressure can be used to verify the presence of left atrial transport function after cardioversion. Steady-state measurements of cardiac output may not be altered by left atrial transport function. Patients who do not immediately demonstrate left atrial transport function or who experience reversion to atrial fibrillation may be evaluated serially.