Effect of postural changes on pulsus alternans: an echocardiographic study.
We describe a patient who had severe left ventricular dysfunction and pulsus alternans following an episode of severe viral myocarditis. Pulsus alternans was mild with the patient in the supine and squatting positions but increased dramatically on standing. Echocardiograms were used to study changes in left ventricular dimension and function with changes in posture. On standing, there was a decrease in the left ventricular diameter and an increase in the absolute and relative shortening fraction and the velocity of shortening on the strong beats, and there was a decrease in end-diastolic dimension and the measurements of ventricular contractility on the weak beats. The marked increase in pulsus alternans during standing may have been induced by increased sympathetic stimulation following the decrease in ventricular loading conditions, while the great beat-to-beat differences in end-diastolic dimension suggest, in addition, the importance of Starling's mechanism.
D000328:Adult; D009202:Cardiomyopathies / Q000175:diagnosis* / Q000503:physiopathology; D004452:Echocardiography; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology*; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D011674:Pulse