Acute and chronic effects of surgical thromboendarterectomy on exercise capacity and ventilatory efficiency in patients with chronic thromboembolic pulmonary hypertension

Objective-To assess acute and chronic effects of surgical thromboendarterec tomy on exercise capacity and ventilatory efficiency in patients with chron ic thromboembolic pulmonary hypertension (CTEPH). Design-Cardiopulmonary exercise testing was performed in 20 patients with C TEPH before thromboendarterectomy (baseline), one month after (early phase) , and four months after (late phase). Peak oxygen uptake (peak Vo(2)) and t he ventilatory response to carbon dioxide production (VE-Vco(2) slope) were measured for assessment of exercise capacity and ventilatory efficiency. R ight heart catheterisation was performed in all patients before and one mon th after surgery. Results-Baseline peak Vo(2) decreased and Ve-Vco(2) slope increased along w ith the increase in pulmonary vascular resistance in patients with CTEPH. A fter thromboendarterectomy, the Ve-Vco(2) slope decreased greatly from base line to the early phase (mean (SD), 50 (9) to 37 (7), p < 0.05) and reached a steady level thereafter. In contrast, a continued increase in peak Vo(2) was noted from the early to the late phase (16.9 (4.1) to 21.1 (5.0) ml/kg /min, p < 0.05). The decrease in the Ve-Vco(2) slope from baseline to the e arly phase, but not the increase in peak Vo(2) correlated strongly with the decrease in pulmonary vascular resistance after surgery (r = 0.75, p < 0.0 1). Conclusions-Thromboendarterectomy may cause an immediate improvement in ven tilatory efficiency, possibly through its beneficial haemodynamic effects. In contrast, exercise capacity may continue to improve towards the late pha se, reflecting peripheral adaptation to exercise.