Electromechanical correlation of leftatrial function after cardioversion.

To study the left atrial function after cardioversion, left ventricular apex cardiogram, electrocardiogram, unipolar and bipolar oesophageal electrocardiogram, and cardiac catheterization were done after 39 procedures in 37 patients with rheumatic heart disease and 2 with atrial septal defect. An 'a' wave in the apex cardiogram representing left atrial contraction appeared in 31 of the 32 records taken 8 hours after cardioversion. Oesophageal electrocardiograms were recorded in I8 patients and in each instance showed separate right and left atrial components ofP wave in the unipolar records and large left atrial waves in the bipolar records. In the pressure tracings an 'a' wave appeared in I9 of the 20 patients in the right atrium and I3 of the i6 subjects in the pulmonary arterial wedge immediately (20 to 40 minutes) after cardioversion. The mean pulmonary arterial wedge pressure decreased after cardioversion in each case. In spite of this the left ventricular stroke work index increased relatively in I2 of the I5 patients, showing improved cardiac performance. It is concluded that there is no true disparity between electrical and mechanical activity of the left atrium, and both are usually restored soon after cardioversion.