[Influence of left ventricular volume changes induced by Valsalva maneuver on R wave amplitude (author's transl)].

Exercise-induced changes of R wave amplitude (delta R) during exercise has been employed to improve the reliability of stress testing in detecting patients with coronary artery disease. Several authors postulated that delta R are related to changes of ventricular volumes. Furthermore Valsalva Maneuver (VM) is able to induce a decrease of left ventricular volumes induced by VM and the variations of R wave. Echocardiographic method was used to determine left ventricular volumes and R wave amplitude changes were evaluated by Frank's lead. Our findings suggest that R wave amplitude changes are not related to variations of cardiac volume. Electrophysiological mechanisms of delta R need further investigation.