Objectives: This study was designed to evaluate the right ventricular function by means of the determination of right ventricular systolic time intervals measured in pulmonary artery flow detected by Doppler.
Background: Left ventricular systolic time intervals have been used to evaluate left ventricular performance. There is, however, no information as to whether right ventricular systolic time intervals may be useful in the evaluation of right ventricular function.
Methods: Simultaneous measurements of right ventricular ejection fraction and Doppler determination of right systolic time intervals were made in four pigs in 47 different hemodynamic conditions that permit the modification of the right ventricular ejection fraction from 15% to 68%. The preejection time, the ratio of right preejection time to right ventricular ejection time, with and without correction by the heart rate, were correlated simultaneously to invasively determined right ventricular ejection fraction and other hemodynamic parameters, measured with a modified pulmonary artery catheter with a rapidly responding thermistor.
Results: There was a significant linear correlation between Doppler determination of right systolic time intervals and right ventricular ejection fraction. A similar correlation was found for preejection time (r = .80, p < .0001) and the ratio of right preejection time to right ventricular ejection time with correction by the heart rate (r = .83, p < .0001). When we used a preejection time > 70 msec as a criterion to detect a ejection fraction < 40% we found a sensitivity of 89% and specificity of 88%. A preejection time > 80 msec, as criterion of more severe ventricular disfunction (ejection fraction < 30%), displayed a sensitivity of 76% and specificity of 100%.
Conclusion: These results show that right ventricular systolic time intervals determined by Doppler study correlate significantly with the right ventricular ejection fraction. In view of its simplicity and its accuracy in the prediction of right ventricular ejection fraction, this method may provide useful non-invasive alternative in the prediction of right ventricular ejection fraction.