Non-invasive evaluation of ventricular function and volumes during atrioventricular sequential and ventricular pacing.

Thirteen patients who all had previously inserted temporary or permanent pacemakers (6, VVI; 7, A-V sequential) were studied by two-dimensional echocardiography and radionuclide gated blood pool ventriculography (RVG) for non-invasive evaluation of cardiac performance. Patients were paced in both the VVI mode and during sinus/atrial or A-V sequential pacing. Although there was no objective change of the ejection fraction during V-pacing and atrial/A-V sequential pacing or sinus rhythm, as has been previously reported, A-V sequential pacing did result in significant improvement in overall cardiac function and output as judged by radionuclide ventriculography and blood pressure response in most of our patients. An appropriately timed atrial contribution to ventricular systole resulted in improved ventricular function in those individuals with pre-existing systolic or diastolic myocardial dysfunction and/or sick sinus syndrome in whom pacemaker therapy was indicated. Radionuclide ventriculography appears to be a reliable, accurate, non-invasive method that can be used to evaluate patients before implantation of a permanent ventricular or atrioventricular pacemaker in order to decide which pacing mode is best for that particular individual.