Usefulness of exercise stress echocardiography in a patient with unilateral pulmonary branch stenosis.

Exercise stress echocardiography (ESE) is a feasible and valuable tool for evaluating subclinical pulmonary hypertension (PH). However, its utility in patients with unilateral pulmonary branch stenosis remains unclear. We present a case involving a 17-year-old patient with left pulmonary branch stenosis who exhibited exercise-induced PH in the contralateral pulmonary artery as detected by ESE. Standard echocardiography was unable to visualize the left pulmonary artery clearly; therefore, computed tomography was performed, revealing a left pulmonary branch stenosis with a minimum diameter of 4.2 mm. Resting echocardiography showed a pressure gradient of 17 mmHg, calculated using the tricuspid regurgitant velocity. During ESE with a prone ergometer, the slope of the mean pulmonary arterial pressure to systemic cardiac output was 3.1 mmHg/L/min, meeting the diagnostic criteria for exercise-induced PH. The patient underwent stent implantation to treat the left pulmonary branch stenosis. Follow-up ESE demonstrated improvement, with the slope of the mean pulmonary arterial pressure to systemic cardiac output decreasing to 1.5 mmHg/L/min. These findings underscore that ESE is both feasible and effective for assessing subclinical unilateral pulmonary branch stenosis. Learning objective: Patients with congenital unilateral peripheral branch pulmonary artery stenosis usually do not have pulmonary hypertension at rest, and identifying patients who require treatment is challenging. Exercise stress echocardiography can detect latent pulmonary hypertension of the contralateral pulmonary artery in some patients, providing valuable insights for determining treatment indications and evaluating the efficacy of catheter interventions for the stenotic lesion.