PATTERNS OF GLOBAL AND REGIONAL SYSTOLIC AND DIASTOLIC FUNCTION IN THE NORMAL RIGHT VENTRICLE ASSESSED BY ULTRAFAST COMPUTED-TOMOGRAPHY

A detailed evaluation of global and regional systolic function and diastolic filling of the human right ventricle has not been previously reported. Ultrafast computed tomography enables simultaneous imaging of the right and left ventricles at an 8 mm slice thickness with a scanning rate of 17 frames/s (50 ms acquisition intervals). In 10 normal men (mean age 26 +/- 4 years) early diastolic filling data were fit to a third order polynomial curve and the peak rate of diastolic filling and time to peak filling were determined globally and regionally at three distinct ventricular levels (apex to base) within each ventricle. The right and left ventricular stroke volumes were not statistically different (89 +/- 8 ml and 90 +/- 8 ml, p = NS), neither were the peak filling rates as referenced to the stroke volume (4.9 +/- 0.9 and 5.3 +/- 0.8 stroke volumes/s, p = NS). Time to peak filling rate was not different between the two ventricles (154 +/- 33 and 161 +/- 18 ms, p = NS). However, reference of stroke volumes and absolute peak filling rates to end-diastolic volumes demonstrated lower dynamic values for the right ventricle (ejection fraction: right ventricle 57 +/- 4%; left ventricle 68 +/- 5%, p < 0.05, and peak filling rate: right ventricle 2.7 +/- 0.4 end-diastolic volumes/s; left ventricle 3.6 +/- 0.5, p < 0.05, respectively). Regionally, basal and apical right ventricular ejection fractions and peak filling rates were similar (62 +/- 4% and 57 +/- 6%; 3.3 +/- 0.3 and 3.4 +/- 0.4 end-diastolic volumes/s p = NS, respectively) and statistically different from midventricular levels (50 +/- 7% and 2.6 +/- 0.3 end-diastolic volumes/s, p < 0.05, respectively). When compared with the same regional values for the left ventricle, right ventricular apical and midventricular levels showed lower values for systolic and diastolic function. In conclusion, when global measurements are referred to stroke volume, a close volumetric and temporal match exists between systolic and diastolic function of the two ventricles. When referenced to the end-diastolic volume, the right ventricle can be considered a lower dynamic chamber. Regionally, segmental ventricular ejection fraction and peak filling rate are characteristically nonuniform across the right ventricle, and when compared with segmental left ventricular function, right ventricular mid and apical segments show lower regional dynamics.