Effect of loss of the atrial contribution to ventricular filling on left ventricular function in patients requiring intermittent pacing with ventricular demand pacemakers

A trial systole enhances ventricular filling and augments cardiac output by about 20%. This capability is lost in patients subjected to ventricular demand pacing (VVI). The effect of VVI pacing on left ventricular function was measured in 9 patients with intermittent complete heart block, by means of echocardiography and radionuclide ventriculography. No statistically significant change in velocity of circumferential fibre shortening, percentage change in left ventricular minor diameter or ejection fraction was shown two weeks and twelve weeks after pacing. It is suggested that intermittent VVI pacing does not lead to impairment of left ventricular function in patients in whom such function is satisfactory prior to pacing. Non-invasive evaluation of left ventricular function before pacing may be of value in choosing the optimal pacing mode.