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.1 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, …