Diastolic Relaxation of the Heart

viewed as rolling downhili from an uphill or This book represents an edited compilation of the scientific presentations given at an Interna- high-energy state. This transition results from tional Symposium on the Physiology of Diastole the opening of membrane pores that allow in Health and Disease, September 11 to 14, calcium to rush into the cytosol, triggering 1986, in Cambridge, Massachusetts. Numerous excitation-contraction coupling. If the energy studies have documented the importance of available to sarcoplasmic reticular and sarcolem- diastolic dysfunction in clinical heart disease. In mal calcium pumps was insufficient to remove recent years clinicians have become increasingly this calcium from the cytosol and res tore the aware that many patients with congestive heart 1O,OOO-fold calcium gradient, characteristic of failure have completely normal myocardial con- the "resting" myocyte, we would live for one tractile function. In these patients, inotropic glorious systole and die in cardiac rigor. The agents provide no clinical benefit and may in well-known phenomenon of rigor mortis re- fact exacerbate clinical manifestations of heart minds us that for skeletal muscles as weIl relaxation is the high-energy state and per- failure. These patients, who may be regarded as having diastolic heart failure, represent a major manent contraction is the inevitable downhili therapeutic challenge today. It has also become state for muscle that can no longer produce increasingly apparent that a variety of patho- adenosine triphosphate.