Assessment of Left Ventricular Diastolic Function: The Power, Possibilities, and Pitfalls of Echocardiographic Imaging Techniques

Abnormal diastolic function portends a poor prognosis regardless of any associated systolic dysfunction. There is controversy regarding the precision with which diagnosis of diastolic dysfunction can be made non-invasively. Clinical studies show that non-invasive evaluation of the severity of diastolic function predicts the risk of cardiac death and heart failure whereas invasive monitoring of intracardiac pressures is not proven to be better than clinical judgement in guiding patient management. The traditional paradigm of centreing the classification of diastolic function on transmitral and transpulmonic flow may no longer be adequate considering the availability of less volume dependent measures of diastolic function. Mitral inflow-based diastolic function assessment is traditionally graded as "normal", "abnormal relaxation", "pseudonormal", and "restrictive filling pattern". However, the transition between various levels of abnormal LV filling pressure is dynamic and related to the ambient heart rate and preload. This dynamic transition makes accurate depiction of severity using just one snapshot of imaging, or single parameters in isolation problematic. Furthermore the prognosis associated with pseudonormal and restrictive filling patterns are comparable. A better understanding of the physiology of diastole highlights the relevance of the cardiac substrate in the genesis of diastolic dysfunction. The availability of newer diagnostic tools such as tissue Doppler imaging has informed the need to assess all components of diastolic function within the context of predisposing or consequential morphological substrates. A new prognosis-centred paradigm implies that diastolic function need only be stratified into "normal", "mildly abnormal" (compensated dysfunction), or "severely abnormal" (uncompensated diastolic dysfunction) categories.