Right ventricular adaptation to pulmonary pressure load in patients with chronic thromboembolic pulmonary hypertension before and after successful pulmonary endarterectomy--a cardiovascular magnetic resonance study.

BACKGROUND

The aim of the study was to characterize RV adaptation to varying loading conditions in patients with chronic thromboembolic hypertension (CTEPH) before and after pulmonary endarterectomy (PEA). Nearly 4% of patients with pulmonary embolism develop CTEPH. PEA offers a cure with excellent outcome. By use of cardiovascular magnetic resonance (CMR) combined with hemodynamic measurements pulmonary arterial elastance (Ea-pulm_i), end-systolic right ventricular elastance (Ees-RV_i) and ventriculo-arterial coupling (Ea-pulm_i/Ees-RV_i) can be studied before and after PEA.

METHODS

Sixty-five patients (mean age 41±12 years, 28 female) underwent CMR pre- and post-PEA. Ejection fraction (EF), end-diastolic (EDVi), end-systolic (ESVi), and stroke (SVi) volumes were indexed for body surface area. Ea-pulm_i was calculated as pulmonary artery mean pressure (mPAP)/SVi, and Ees-RV_i as mPAP/ESVi.

RESULTS

mPAP decreased from 47±12 to 25±9 mmHg, p=0.0001. Ea-pulm_i was increased before PEA and normalized afterwards (2.8±2.1 vs. 0.85±0.4 mmHg/ml/m2, p=0.0001). Ees-RV_i was depressed before and after PEA (0.72±0.27 vs. 0.66±0.3 mmHg/ml/m2, p=0.13). EF improved from 25±12% to 46±10%, p=0.0001, because ventriculo-arterial coupling was restored (4.2±3 vs. 1.4±0.6, p=0.0001). EDVi and ESVi mproved significantly (EDVi 92±32 to 72±23 ml, p=0.0001; ESVi 69±31 to 41±18 ml, p=0.0001).

CONCLUSION

RV function is largely determined by afterload and returns to normal once afterload is normalized. This is paralleled by a significant improvement of CMR indices of right ventricular remodelling.