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 (E_{a-pulm_i}), end-systolic right ventricular elastance (E_{es-RV_i}) and ventriculo-arterial coupling (E_{a-pulm_i}/E_{es-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 (EDV_i), end-systolic (ESV_i), and stroke (SV_i) volumes were indexed for body surface area. E_{a-pulm_i} was calculated as pulmonary artery mean pressure (mPAP)/SV_i, and E_{es-RV_i} as mPAP/ESV_i.

Results

mPAP decreased from 47 ± 12 to 25 ± 9 mmHg, p =0.0001. E_{a-pulm_i} was increased before PEA and normalized afterwards (2.8 ± 2.1 vs. 0.85 ± 0.4 mmHg/ml/m², p =0.0001). E_{es-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). EDV_i and ESVi mproved significantly (EDV_i 92 ± 32 to 72 ± 23 ml, p =0.0001; ESV_i 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.