Normal Range of Mechanical Variables in Pulmonary Hypertension: A Tissue Doppler Imaging Study

Abstract

Tissue Doppler imaging (TDI) has been quite useful in determining the mechanical properties of right ventricular (RV) function in patients with pulmonary hypertension (PH). However, to what extent these mechanical properties are expected to identify RV dysfunction in PH patients is less clear. Our echocardiography database was queried for patients with PH of different etiologies (111 patients, age 55 +/- 14 years, mean pulmonary artery pressure 63 +/- 24 mmHg) who had undergone TDI analysis and compared to similarly collected data from a group of healthy individuals (35 patients, mean age 45 +/- 15 years, mean pulmonary artery pressure 27 +/- 5 mmHg). ROC analysis demonstrated that a mechanical delay between the RVFw and IS > 25 ms detects PH while a delay > 37 ms detects abnormal RV performance. Peak RV strain < -20% identifies PH greater than 40 mmHg and a reduced RV systolic function. However, on a stepwise multiple regression analysis model RV dyssynchrony was the most significant predictor of PH (r = 0.515; P = 0.0003) over peak longitudinal RV strain (r = 0.553; P = 0.02) and RVFAC (r =-0.603; P = 0.01). Peak longitudinal strain was the most significant predictor (r =-0.722; P < 0.0001) of an abnormal RVFAC over PH (r =-0.603; P = 0.004) and RV dyssynchrony (r =-0.471; P = 0.01). A normal range of RV mechanical variables in PH patients are provided that can be applied in the assessment of RV performance.