Exercise Doppler echocardiography to detect early changes in the right ventricular-pulmonary circulation unit after pulmonary embolism

Abstract Introduction After pulmonary embolism (PE), patients frequently complain about reduced exercise capacity and dyspnea on exertion, even without pulmonary hypertension (PH). The underlying condition is often chronic thromboembolic disease, which is caused by residual pulmonary obstruction with preserved resting pulmonary haemodynamics. The symptoms are the consequences of the increased dead space ventilation, exercise-induced PH and right ventricular (RV) dysfunction. We aimed to assess the pathologic differences in the echocardiographic parameters of the RV- pulmonary circulation unit among patients with previous PE and the healthy control group. Furthermore, an objective was to compare the hemodynamic response to stress after different treatment strategies (thrombolysis vs. heparin administration). Methods 21 patients after PE (mean age 58,5±12,1 years; 53% men) have been included in the study. All of them were effectively anticoagulated for at least three months, and none had any signs of PH on echocardiography at rest. The control group included 20 healthy volunteers (mean age 56,9±11,5 years; 55% men). Each patient underwent resting and exercise stress echocardiography on a semi-recumbent bicycle ergometer according to a standardised protocol until the maximally tolerated workload. Echocardiography was performed at rest, at 50 Watt workload and during peak stress. The measurements focused on the RV's systolic function (TAPSE), the estimated pulmonary artery systolic pressure (PASP), and the Doppler measurements in the RV and left ventricular outflow tracts. Pulmonary vascular resistance (PVR) and RV-pulmonary artery coupling (RV-PA) were calculated from the echocardiographic parameters. Results The post-PE group had significantly higher PASP (39,2 ±16,6 vs. 27,7±12,5 mmHg; p<0,05) and PVR (1,5±0,4 vs. 1,1±0,3 Wood Units; p<0,05) at peak stress, than the controls. 55% of post-PE patients remained symptomatic, but there were no significant differences between the symptomatic and asymptomatic groups regarding TAPSE, PASP, RV-PA coupling and PVR. 30% of post-PE patients had thrombolysis. In the patients where thrombolysis was performed, the coupling at peak stress was significantly higher than in heparin-treated patients (1,4±0,1 vs 0,9±0,4 mm/mmHg, p<0,05). Conclusion Post-PE patients without resting PH have higher PVR and PASP than the healthy control group, even after at least 3 months of adequate therapy. Post-PE patients treated with thrombolysis may have more preserved RV-PA coupling than the heparin-treated patients.