The inhomogenous movement of the left ventricle induced by coronary artery occlusion.

The pattern of myocardial segment length change in an ischemic and nonischemic area of the left ventricle was studied acutely following ligation of the LADA in the dog. Results were interpreted in relation to other hemodynamic findings obtained in the same experiments. Paradoxical bulging during systole was found in the ischemic area, whereas increased shortening during systole was found in the nonischemic area. Since there was no increase in cardiac output or aortic pressure, it was assumed that the increased energy released by the nonischemic area of the ventricle was expended in stretching myocardial fiber in the ischemic area. Under the condition of ventricular afterloading, increased systolic bulging of the ischemic area and increased systolic shortening of the non ischemic area were noted. With maximum afterloading, systolic bulging of the ischemic area was diminished and ventricular systolic pressure increased. This suggested that a reduction in ventricular wall compliance might improve the function of the partially ischemic ventricle by diminishing the amount of energy expended during systole in stretching muscle fiber in the ischemic area.