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

We described 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 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 posterio...