Intraoperative 3-Dimensional Echocardiography-Derived Right Ventricular Volumetric Analysis in Chronic Thromboembolic Pulmonary Hypertension Patients Before and After Pulmonary Thromboendarterectomy

Abstract

Objectives: To assess the change in 3-dimensional (3D) echocardiography-derived right ventricular volumes before and after pulmonary thromboendarterectomy (PTE) and to evaluate the correlation of these variables with right heart catheterization-calculated pulmonary vascular resistance (PVR).

Setting: Single university hospitals.

Participants: Patients undergoing elective PTE surgery between November 2016 and February 2018.

Methods: All patients received a pulmonary artery catheter and arterial line, and transesophageal echocardiographic monitoring was performed. Transesophageal echocardiographic monitoring before surgery (pre-PTE) and postsurgery (post-PTE) included comprehensive 2D examinations and 3D right ventricular data set acquisition for offline volumetric analysis. Right ventricular fractional area of change (RVFAC) was measured from a right ventricular-focused midesophageal 4-chamber view. TomTec-Arena 4D RV-Function 2.0 offline software (TomTec Imaging Systems GmbH, Unterschlessheim, Germany) was used to measure right ventricular end diastolic volume (RVEDV), right ventricular end systolic volume (RVESV), and right ventricular ejection fraction (RVEF). Paired t tests were used to evaluate for differences before and after surgery, and echocardiographic variables versus PVR were analyzed with linear regression.

Results: Forty patients were scheduled for elective PTE surgery; 35 patients had complete hemodynamic profiles and echocardiographic data sets and were included in the evaluation. Mean pulmonary artery pressure decreased from 40 ± 11 to 28 ± 7 mmHg, and PVR decreased from 708 ± 432 to 285 ± 136 dynes*s/cm⁵ after PTE. RVEDV decreased from 106 ± 43 to 79 ± 35 cm³ (p < 0.001), and RVESV decreased from 77 ± 36 to 59 ± 31 cm³ (p < 0.001). A statistically significant change was not identified in RVEF or RVFAC post-PTE compared with pre-PTE values. All volumetric analyses and RVFAC correlated poorly with PVR (pre-PTE RVEDV correlation to PVR [R² = 0.004]; post-PTE RVEDV correlation to PVR [R² = 0.024]).

Conclusion: Even though RVEDV and RVESV displayed a statistically significant change after PTE, this study did not identify a correlation between those variables and PVR. In addition, markers of right ventricular systolic function (eg, RVFAC and RVEF) did not correlate with PVR. Therefore, the authors conclude that even though these echocardiographic measurements quantified a statistically significant change after PVR reduction, they cannot be reliably used as a surrogate marker of success immediately after PTE.

Keywords: chronic thromboembolic pulmonary hypertension; pulmonary thromboendarterectomy; right ventricular function; right ventricular volumes; three-dimensional echocardiography.