Apperceptive signals demonstrating the dynamic disturbance of myocardial ischemia

Analog pressure signals (catheter-tip manometers) from the left atrium, left ventricle, and aorta and a flow signal from the arota were obtained in 25, open-chest, anesthetized dogs in which 115 episodes of ischemia were produced in an area of the left ventricle subtended by the distal left anterior descending coronary artery and its last major diagonal branch. The left ventricular pressure and its first derivative (dP/dt) were displayed as an X-Y loop. The character of this loop went through a unique series of dynamic changes in 110 of the 115 ischemic episodes, indicating that this is a useful tool for monitoring myocardial ischemia. Spectrum pairs of the above signals were analyzed with digital computational transfer functions in 14 ischemic episodes of three experiments and preliminary assessment reveals unique pole and zero changes in many pairs during each episode which also may prove to be a useful indicator of the hemodynamic disturbance incurred during myocardial ischemia.