Echo-Doppler assessment of diastole: flow, function and haemodynamics.

To cite: Gillebert TC, De Pauw M, Timmermans F. Heart 2013, 99, 55–64. The concepts related to diastolic function were developed by muscle physiologists and by cardiologists with a strong background in physics (cardiac mechanics and fluid dynamics). These scientists described left ventricular (LV) material properties in terms of pressures and volumes, and their mutual relation. When a given volume is added to a ventricle, pressure rises more in a diseased ventricle, which is stiffer or less compliant. These scientists also focused on the dynamics of myocardial relaxation and evaluated the speed of this process by fitting an exponential relation to LV pressure fall, and by calculating the time constant of isovolumetric relaxation tau (τ). A prolonged time constant is associated with a delayed myocardial relaxation, and possibly also with a relaxation that is incomplete and still ongoing at end-diastole. Both decreased compliance and delayed relaxation may induce increased filling pressures, hence heart failure. The measurement of relaxation, compliance and diastolic pressures require the presence of a high fidelity pressure catheter in the LV cavity. This limits the use to clinical situations where an invasive procedure is warranted. Such an invasive procedure, however, remains the golden standard when non-invasive measurements are inconclusive. A less invasive procedure is pulmonary artery catheterisation and measurement of the pulmonary capillary wedge pressure (PCW) as a surrogate for left atrial (LA) or LV filling pressures. Echocardiography and cardiac Doppler have played an important role in the evaluation of diastolic function since the pioneering work of Liv K Hatle in the mid 1980s. She initiated and supported research, initially in Trondheim (Norway) and later at Stanford (Palo Alto, California, USA) and the Mayo Clinic (Rochester, Minnesota, USA). She was the first to contrast mitral inflow signals to invasively measured filling pressures. With the extraordinary development of cardiac imaging, cardiologists started to look at haemodynamics and at diastolic function, trying to evaluate filling pressures with mitral flow and more recently with tissue Doppler. In addition to evaluating filling pressures, non-invasive imaging has the advantage of giving a comprehensive overview of LV morphology and function, LA size and function, right ventricular pressure and function, and venous congestion. This has led to the surprising evolution that young cardiologists have learned to guide patient management with echo-Doppler indices, and to use them not anymore as surrogates for invasive measurements but as physiological findings in their own right. Echocardiography has become the cornerstone of the evaluation of diastolic function because of its non-invasive character and because of the possibility to repeat recordings in the same patient, and to compare consecutive findings. The strength of this approach is to use the patient as his or her own control. Data are recorded under optimised therapy and, in order to evaluate changes in haemodynamics, the follow-up Doppler signals are compared to those optimised data. The present article highlights the clinically most relevant aspects of the recent European Association of Echocardiography/American Society of Echocardiography (EAE/ASE) recommendations for the evaluation of LV diastolic function by echocardiography. For more detailed information, the reader is directed to these recommendations.