Webster's Revised Unabridged Dictionary · 1913

Hemisystole

Hemisystole , noun

(Physiology) Contraction of only one ventricle of the heart.

Hemisystole is noticed in rare cases of insufficiency of the mitral valve, in which both ventricles at times contract simultaneously, as in a normal heart, this condition alternating with contraction of the right ventricle alone; hence, intermittent hemisystole.