The pulmonary trunk arises from the right ventricle at the pulmonary valve and ascends for approximately 5 cm before bifurcating beneath the aortic arch into the right and left pulmonary arteries at the level of the sternal angle. It lies entirely within the pericardium and is anterior to the ascending aorta before passing to its left. The ductus arteriosus in fetal life connects the pulmonary trunk to the aortic arch, becoming the ligamentum arteriosum after birth.
The pulmonary trunk carries deoxygenated blood from the right ventricle to the lungs, the only artery carrying venous blood. Pulmonary trunk dilation occurs in pulmonary arterial hypertension and can produce compression of the left recurrent laryngeal nerve, a cause of cardiovocal (Ortner) syndrome. Massive pulmonary embolism occluding the main pulmonary trunk produces sudden cardiovascular collapse from right ventricular outflow obstruction. The main pulmonary artery is the site of pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension.
Acute thrombotic occlusion of the pulmonary trunk or bilateral main pulmonary arteries causes catastrophic right ventricular outflow obstruction producing haemodynamic collapse, managed with systemic thrombolysis or surgical embolectomy as a life-saving procedure.
Progressive elevation of pulmonary artery pressure from various causes produces right ventricular hypertrophy, pulmonary trunk dilation, and ultimately right heart failure, managed with targeted pulmonary vasodilator therapy and, in end-stage disease, lung transplantation.
