Assessment of pulmonary vascular response to exercise with Doppler-echocardiography: state of the art?

There is growing evidence that the evaluation of lung circulation and right ventricular function at rest and during exercise can be helpful to detect exercise induced pulmonary hypertension (1-4), unmask an early pathological involvement of the pulmonary circulation (5,6) and to stratify the prognosis (1,7). Routinely, its evaluation is performed by assessment of the tricuspid regurgitation velocity (TRV), which allows an estimation of systolic pulmonary arterial pressure (sPAP) (8). The recent work by van Riel and collaborators addresses the question, whether estimation of pulmonary pressures during exercise using stress-Doppler echocardiography is accurate and allows diagnostic statements (9). The strength of this study is, that the investigators performed echocardiography and right heart catheterization simultaneously. The study showed high correlations of invasive and noninvasive assessments, both at rest and during exercise, as long as TRV signals revealed a good quality (9). At rest in 68% of patients TRV Doppler envelopes revealed a high quality and highly correlated with the invasive measurements. However, during exercise only 22 patients among 65 (34%) presented a good quality. Lower quality TRV signals correlated poorly with invasive measurements. Thus, according to this study stress-Doppler echocardiography is very limited to assess pulmonary artery pressures in daily practice if only one third of patients can be assessed adequately. Patients with abnormal mean pulmonary artery pressures defined as increase >3 mmHg/L mean cardiac output/minute were identified with a high sensitivity and specificity using a threshold of 1.4 mmHg/10 W of exercise workload. Also in this case, in patients with modest or bad quality TR profiles, it was impossible to find any relevant echocardiographic index able to predict the presence of an invasively assessed exercise-PH