Assessment of right ventricular function by intravenous infusion of krypton-81m

Kr-81m equilibrium ventriculography was used to assess right ventricular (RV) function at rest (R) and during submaximal bicycle exercise (E) in patients (pts) with different cardiopulmonary disorders. Kr-81 was continuously eluted in 5% dextrose from a portable Rb-81 generator and infused through a peripheral vein. Due to the short half-life (13s) and the free diffusibility of Kr-81 through the alveolar membrane, activity in the left side of the heart is negligible. This allows imaging in a RAO position which provides the best separation between the right atrium and the RV. Determination of RV ejection fraction (RVEF) involved the definition of an endiastolic and an endsystolic region of interest by a semiautomatic computer algorithm. The standard deviation of RVEF determinations by two independent observers was 0.047. Kr-81 RVEF was related to X-ray angiographic (XR) RVEF and hemodynamic measurements. The correlation coefficient between Kr-81 and XR RVEF was 0.82(n=25). When all pts were divided into two groups according to their mean pulmonary artery pressure, significant differences in the RVEF during E between these groups were found with both Kr-81 and XR ventriculography. The correspondence between KR-81 and XR data underlines the potential of Kr-81 as a reliable noninvasive tool in assessing RV more » function. « less