Right and left ventricular diastolic flow field: why are measured intraventricular pressure gradients small?

Right and left ventricular (RV/LV) diastolic filling involves rapidly changing flow in a chamber with geometry undergoing temporal changes in size and shape; the right ventricle is the most challenging to model analytically, looking triangular when viewed from the front, and having irregular crescent-shaped transverse cross-sections. Accordingly, diastolic fluid dynamics in health and disease are fraught with difficulties. All the same, ventricular diastolic filling abnormalities and diastolic dysfunction are important components of heart failure, recognized in the current International Classification of Diseases (ICD-10, codes I50.30-33). It is now widely appreciated that the clinical significance of diastolic dysfunction is far-reaching. However, the fact that RV/LV filling is dependent on a large number of factors and interactions renders its clinical assessment and evaluation difficult. In this brief article, I will focus on clinically important cardiodynamic concepts concerning interactions of underlying fluid dynamic mechanisms with intracardiac filling patterns. These interactions are responsible for the smallness of measurable transvalvular atrioventricular and intraventricular filling pressure gradients.