Correlation of the Tei index with invasive measurements of ventricular function in a porcine model

Background: The Doppler myocardial performance (Tei) index has been reported to be clinically useful in assessing left ventricular systolic and diastolic function in both adults and children. However, there are limited data to compare the Tei index with invasive measurements of ventricular function. We used a porcine model to directly correlate the Tei index with invasive indices of systolic and diastolic function. Methods. Pressure volume loops were obtained from 10 pigs (32-45 kg). A micromanometer and a conductance catheter were placed in the left ventricle to record pressure and volume, respectively. A flow probe was placed around the ascending aorta to record cardiac output. Baseline pressure volume loops were generated during preload reduction through caval occlusion. Epicardial echocardiogram were performed just before the caval occlusion. Invasive indices including preload recruitable stroke work, ventricular stiffness constant, and cardiac output were assessed, as were noninvasive echocardiographic indices including Tei index and ejection fraction. An ischemic insult, ventricular fibrillation, was induced to alter ventricular function. After cardioversion and 40 minutes of reperfusion, echocardiographic and invasive measurements were repeated. Results: There was a statistically significant inverse relationship between the percent change in Tei and the percent change in preload recruitable stroke work after ventricular fibrillation (r = -0.70, P = .02), although the correlation between the actual values of Tei and preload recruitable stroke work were not statistically significant. There was a statistically significant inverse relationship between the percent change in Tei and the percent change in cardiac output (r = -0.65, P = .03). There was a direct correlation between the value of Tei and the ventricular stiffness constant at baseline (r = 0.63, P < .05). As anticipated, the value of Tei was inversely related to ejection fraction by epicardial echocardiogram at baseline (r = -0.85, P < .001). The percent change in Tei was inversely related to the percent change in ejection fraction as well (r = -0.699 P < .05). Conclusions: This animal model is one of the first studies to demonstrate a direct correlation between the Tei index and systolic and diastolic invasive measurements of ventricular function. This supports the clinical use of this index as a measure of global ventricular function.