Aims: Transthoracic echocardiography is a useful technique for non-invasive detection of pulmonary arterial systolic pressure (PASP). Isovolumic relaxation time (IVRT) measured by Doppler tissue imaging (DTI) is a sensitive measurement of changes in pulmonary vasculature. Our aim was to validate IVRT in the echocardiographic assessment of pulmonary hypertension (PH) patients.
Methods and results: We studied 196 PH patients (67% women, mean age 51.8 ± 16.6 years, mean PASP: 81 ± 24 mmHg) and 37 consecutive age- and sex-matched controls (58% women, mean age 44.7 ± 16.4 years, mean PASP 27.7 ± 5.5 mmHg). The estimation of PASP was derived from tricuspid regurgitation velocity according to the Bernoulli equation. The measurement of IVRT was calculated using pulsed tissue Doppler. In the PH group and in the healthy volunteers group (P < 0.0001), the average IVRT was 113.4 ± 28.5 ms [95% confidence interval (CI): 109-117] and 41 ± 12.5 ms (95% CI: 37-45), respectively. We found a strong correlation between IVRT and systolic pulmonary pressure in the PH group (r = 0.52, P < 0.0001) and a cut-off of 75 ms showed a sensitivity and specificity of 94% and 97%, respectively, for the prediction of elevated PASP.
Conclusion: The determination of IVRT by DTI is a simple and reproducible method that correlates well with PASP. It is, therefore, a parameter to consider in the echocardiographic assessment of patients with PH, and may be particularly important when the tricuspid Doppler signal is poor.