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

Abstract

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