Cardiac Disease and Its Treatment—Some Physiological Correlations

Certain aspects of cardiac function as related to the normal and diseased heart are summarized. Topics discussed include: [1] myocardial ultrastructural-functional relationships; [2] the process of electrical excitation and conduction and the basic physiology of arrhythmias and conduction defects; [3] methods of evaluation of myocardial failure in the patient and present concepts of the cellular basis of heart failure; and [4] the role of the ions in the control of the myocardial contractile process and the possible relationships between ionic flux and digitalis action. Dr. Glenn A. Langer (Departments of Medicine and Physiology): Over the past few years a good deal has been learned about various aspects of ultra-structure, electrophysiology, metabolism, and ionic exchange in the myocardium. Each of our partici-pants will focus on one of these aspects and relate it to the function of the normal or diseased heart. Dr. Sopis will review the ultrastructure of the myocardial cell and relate it in general terms to func-tion. Dr. Brady will then discuss the basis of electrical activity in the cell and relate this, again in general form, to arrhythmias and conduction defects. Dr. Shine will discuss current concepts of the status of heart muscle in failure and some of its physiological bases. Finally I will review our present concepts of the role of ions in the regulation of contractile re-sponse, and our view on how digitalis augments tension development