AbstractAbnormalities of diastolic function are increasingly recognized as important components of the abnormal physiology in many patients with heart failure. In order to better understand the role of abnormalities of individual parameters or diastolic function affecting filling of the left ventricular a broader understanding of the relationship of systolic and diastolic performance on overall left ventricular pump performance should be considered. While measurement of diastolic function noninvasively has become the predominant way of assessing diastolic performance, invasive evaluation remains important. Moreover, understanding the physiology of diastolic performance remains essential to proper diagnosis and management. Cathet Cardiovasc Intervent 2001;53:85–93. © 2001 Wiley‐Liss, Inc.