Contraction augmentation in left ventricular nonischemic region during ischemia

We display the contraction augmentation phenomenon in left ventricular (LV) nonischemic wall during ischemia, with a simplified cardiovascular system model. The model is composed of a two-zone left ventricle, a preload equivalent and an afterload equivalent. Geometry of the LV shape was assumed to be truncated-spherical and the ischemic zone size was allowed to be altered. The model predicts that during ischemia the systolic shortening (SS) in the nonischemic region will increase from 12.04 (control) to 19.33%, but for the ischemic region SS will decrease from control to -1.81%. In addition, the isovolumic shortening (IS) and ejection shortening (ES) are all increased in the nonischemic region when compared to the preischemic condition. Based on the modeling results, it is concluded that augmentation during ischemia can in part be explained by the shifting of the blood volume from the nonischemic to ischemic zone, which is resulted from the diminished contractile force in ischemic muscle