During the two cardiac cycle including the matching phase and the compensation phase of premature beat, the average work of left ventricle was decreased 9.0% by VPB, 3. 3 % by JPB and 3.0% by APB.

• 在配对间期和代偿问期两个心动周期中，一次室早、房早和交界性早搏分别使心脏减少作功9．0%25、3．0%25、3．3%25。