Echocardiographic Assessment of Right Ventricular Diastolic Function in Children and Adults: Present State and Future...

Diastolic function plays an important but often overlooked role in overall ventricular performance and is comprised of a sequence of events, which together result in adequate filling at low filling pressures. From a physiologic point of view there are 2 distinct, yet related periods that drive diastole: active relaxation and late filling. Much of the literature on diastolic function focuses on the left ventricle, however, there are significant differences in morphology, physiology, and adaptation between ventricles. Echocardiographic assessment of right ventricular diastolic function is challenging because of our imperfect understanding of right ventricular physiology, suboptimal imaging tools, and the use of models that have been built using the left ventricle. Conventional assessment includes inferior vena cava size, right atrial volume, and the use of Doppler to quantify tissue and blood velocity. In adults, the tricuspid valve E wave to A wave ratio (TV E/A) used in combination with early diastolic tricuspid valve annular velocity (e') and inferior vena cava size can be used to classify diastolic impairment, however, in children these are dependent to a greater degree on age and pathology. Right atrial and ventricular strain suffers from fewer limitations and might show incremental benefit, however, remains understudied, particularly in children. Novel methods made possible with ultrafast ultrasound provide a means to noninvasively assess intraventricular pressure differences as a measure of active relaxation, and shear wave velocity to directly assess myocardial stiffness, however, these remain in preclinical stages. In this review we discuss right ventricular diastolic physiology, the current state, and limitations of echocardiographic evaluation, and explore promising new methods for its assessment.