Diastology for the clinician

Diastolic filling of the heart is a complex sequence of multiple inter-related events consisting of processes such as ventricular relaxation, erectile coronary effect, visco-elastic forces of the myocardium, ventricular interaction, myocardial stress strain relationships, pericardial restraint, passive filling, and atrial contraction. However, in order to understand diastolic filling from a clinical aspect, a simplified foundation can be used which divides the cardiac cycle into contraction, relaxation, passive filling, and filling at atrial contraction. The mitral flow velocity curves are representative of the relative driving pressure between left atrium and left ventricle and allow one to grade the progression of diastolic dysfunction which occurs in disease states. Doppler tissue imaging is necessary as a surrogate of ventricular relaxation to further determine the stages of diastolic dysfunction in patients with preserved ejection fraction. These Doppler flow velocity curves can be applied to understanding diastolic filling of the heart in patients with both reduced ejection fraction and preserved ejection fraction.