Experimental study of right ventricular structure and function by contrast-enhanced transthoracic echocardiography

Objective To investigate the accuracy and repeatability of contrast-enhanced transthoracic echocardiography for measurements of right ventricular structure and function. Methods The apical four-chamber views and the three-dimensional full-volume images of the right heart were collected from 12 beagles with unenhanced and contrast-enhanced transthoracic echocardiography. The intimal display rate of the right ventricular segments, right ventricular end diastolic longitudinal dimension (RVLD), right ventricular end diastolic area (RVEDA), right ventricular end systolic area (RVESA) and right ventricular fractional area change (RVFAC) were evaluated respectively with two-dimensional unenhanced and contrast-enhanced echocardiography. Right ventricular three-dimensional full-volume images were processed and analyzed by TomTec software, and right ventricular end diastolic volume (RVEDV), right ventricular end systolic volume (RVESV) and right ventricular ejection fraction (RVEF) were measured respectively with three-dimensional unenhanced and contrast-enhanced echocardiography. The measurements of pathological specimen were taken as the gold standard, the accuracies of measuring RVEDVand RVLD by different methods were evaluated. All indexes were measured repeatedly by the same observer and different observers to assess the intraobserver and interobserver reproducibilities of different methods. Results ①The intimal display rate of the right ventricular segments was higher with contrast-enhanced echocardiography than that with unenhanced echocardiography (P<0.05). ②The measurements of RVEDV by three-dimensional contrast-enhanced echocardiography correlated well with the measurements by anatomical specimens. And the correlation was higher (0.916 vs 0.843), the consistency was better than that by unenhanced echocardiography. The measurements of RVLD by two-dimensional contrast-enhanced echocardiography correlated well with the measurements by anatomical specimens. And the correlation was higher (0.928 vs 0.850), the consistency was better than that by unenhanced echocardiography. ③For inter- and intraobservers reproducibilities, the interclass correlation coefficients of RVLD, RVEDV, RVESV, RVEF, RVEDA, RVESA, RVFAC with contrast-enhanced echocardiography were higher and 95% confidence interval ranges were smaller than those with unenhanced echocardiography. Conclusions Contrast-enhanced transthoracic echocardiography can improve the accuracy and repeatability for measurements of right ventricular structure and function, providing a new evaluation method for patients with poor image quality of the right ventricle in clinical practice. Key words: Echocardiography; Ventricular function, right; Ultrasound enhancing agents