Hemodynamic profiles in patients with chronic thromboembolic disease before and after pulmonary endarterectomy

Background: Patients with chronic thromboembolic disease (CTE) may suffer from disabling exercise intolerance without pulmonary hypertension at rest. Long-term prognosis in these patients is excellent and surgery not absolutely mandatory. Pulmonary endarterectomy (PEA) however is offered in some centres with improvement of symptoms and quality of life. Objectives: We studied the pathophysiology of the exercise limitation in CTE patients, and determined the underlying mechanisms of the PEA-induced improvement. Methods: In 14 CTE patients, a cardiopulmonary exercise test (CPET) was performed during right heart catheterization. One year after PEA, non-invasive CPET was performed to assess the effects of surgery on exercise physiology. Results: Upon exercise, we observed a mean pulmonary arterial pressure/cardiac output slope (mPAP/Q) of 2.7±1.2 mmHg.min.L -1 , a decrease in mean pulmonary compliance from 5.3±1.8 to 2.8±1.1 mmHg.ml -1 (p d /V t ) from 0.43±0.09 to 0.48±0.07 (p=0.03). The mPAP/Q slope correlated with V d /V t (p=0.028) and with the non-invasive CPET derived V9 E /V9CO 2 slope (p=0.017). Nine patients subsequently underwent PEA; after one year the V9 E /V9CO 2 slope had decreased (p=0.014); and, the oxygen pulse increased (p=0.027) and the heart rate response decreased (p=0.003). Conclusions: Our observations point to an abnormal pulmonary vascular response to exercise and a decreased ventilatory efficiency as mechanisms underlying the exercise limitation observed in CTE patients. PEA resulted in improvements in circulatory responses indicative for an improved stroke volume response upon exercise and ventilatory efficiency.