Comparison of bronchopulmonary collaterals and collateral blood flow in patients with chronic thromboembolic and primary pulmonary hypertension

Objective-To compare the visualisation of bronchopulnonary collaterals and bronchopulmonary collateral blood how in patients with chronic thromboembolic pulmonary hypertension and primary pulmonary hypertension. Setting-Referral centre for cardiology at an academic hospital. Patients-Nine patients with chronic thromboembolic pulmonary hypertension and 17 with primary pulmonary hypertension. Interventions-Bronchopulmonary collaterals were visualised by selective bronchial arteriography or thoracic aortography. Bronchopulmonary collateral blood flow was estimated by injecting indocyanine green into the ascending aorta and sampling below the mitral valve from the left ventricle. Results-The degree of pulmonary hypertension was comparable in the two groups. Large bronchopulmonary collaterals were visualised in all the patients with thromboembolic pulmonary hypertension who had bronchial arteriography or aortography or both. None of the primary pulmonary hypertension group studied by aortography had bronchopulmonary collaterals (P << 0.001). All the patients with chronic thromboembolic pulmonary hypertension had significant bronchopulmonary collateral blood flow, which was (mean (SD)) 29.8 (18.6)% of the systemic blood flow. There was no recordable collateral blood flow in 11 of 15 patients with primary pulmonary hypertension. In the remaining four patients the mean value was 1.1 (1.8)% of the systemic blood flow (P << 0.001). Conclusions-Visualisation of bronchopulmonary collaterals by thoracic aortography or by bronchial arteriography, or the demonstration of an increased bronchopulmonary collateral flow, helps to distinguish patients with chronic thromboembolic pulmonary hypertension from those with primary pulmonary hypertension.