Echocardiography in mechanical alternans. With a note on the findings in discordant alternans within the left ventricle.

Abstract

SUMMARY We describe the echocardiographic manifestations of mechanical alternation of left ventricular (LV) contraction during regular sinus rhythm. Chronic LV dilatation and failure existed in all our four cases. Alternation was observed with respect to the following echocardiographic variables: amplitude and rate of increase of amplitude of systolic excursions of the LV posterior wall and ventricular septum (VS); reciprocal changes in the duration of LV ejection and pre-ejection periods (on the aortic valve echo) such that the SINCE PULSUS ALTERNANS was first described by Traube,' it has been the subject of extensive experimentation and comment, including a recent review.2 In addition, a number of hemodynamic studies have been carried out in man.3-10 Katz and Feil in 1937,11 and more recently, Spodick and St. Pierre"2 used phonocardiography and systolic time intervals in external arterial pulse tracings to investigate the pathophysiology of mechanical alternans. Visualization of alternately strong and weak ventricular contractions has been obtained by angiocardiographic methods,"M but hitherto, to our knowledge, no echocardiographic description of the phenomenon has appeared. Case Reports Patient 1Patient 1, a 30-year-old woman, had been admitted on several occasions for recurrent heart failure since the postpartum onset of her symptoms five years earlier. On examination she exhibited florid signs of severe left and right heart failure, including dyspnea at rest, orthopnea, basal pulmonary rales, gallop rhythm, and hepatomegaly. Pulsus alternans was evident on palpation of the radial pulse, and confirmed by sphygmomanometry which showed a difference of 15 to 20 mm Hg in systolic pressure between alternate beats. Her electrocardiogram (ECG) showed left ventricular (LV) hypertrophy and strain, and regular sinus rhythm with occasional ventricular premature beats. No electrical alternans was present. Her chest roentgenogram revealed considerable cardiomegaly and pulmonary venous congestion. An external carotid pulse tracing depicted an alternation in the amplitude of the arterial pulse, at a regular heart rate. total duration of LV electromechanical systole remained constant; reciprocal changes in the duration of RV ejection and pre-ejection periods (on the pulmonic valve echo) such that the total duration of RV electromechanical systole remained constant; systolic anterior excursion of the aortic root as a whole; steepness of the mitral EF slope; septal and LV posterior wall diastolic position; and end-systolic LV diameter. In two patients, discordant alternans of the motion of the LV posterior wall and the VS was observed.Echocardiography was performed using a Picker Echoview 10 ultrasonoscope connected to a Honeywell 1856 strip-chart Visicorder. Echocardiography of the aortic root ( fig. 1, top) showed alternation in the amplitude of anterior systolic motion of the aortic root as a whole, and in the velocity of this anterior excursion. Alternation was manifest also in the duration of systolic opening of the aor...