2009 Laennec Clinician/Educator Lecture—Diastolic Function: Past, Present, and Future
One hundred years ago, research by Otto Frank, Carl Wiggers, and Yandell Henderson identified cardiac tonus and variable diastolic relaxation as important aspects of cardiac function. Belief in the existence of cardiac tonus and variable relaxation then went into eclipse from 1930 to 1970, during which time the application of A.V. Hill’s equations of muscle mechanics (derived from experiments on skeletal muscle) to cardiac physiology assumed that cardiac muscle was basically a “twitch” muscle and was completely passive between contractions. For the past 40 years, there has been a resurgence of interest in and experimental support for the concept of variable diastolic relaxation. At the same time, improved clinical measurement techniques have allowed simultaneous measurement of left ventricular pressure and volume, establishing firmly the existence and importance of rapidly occurring shifts in the diastolic left ventricular pressure–volume relation. Today, it is clear that up to 50% of patients presenting with acute heart failure manifest as pulmonary edema are exhibiting increased resistance to diastolic left ventricular filling as their primary problem, rather than impaired contractile function and reduced left ventricular systolic emptying. Many causes of increased resistance to diastolic left ventricular filling occur clinically, including myocardial hypertrophy, ischemia, diabetes, and increased coronary venous pressure, and may be modifiable with appropriate therapy. Examples will be presented.