Overview A permanent arterial trunk is one in which both the left and right ventricles emit blood to a common arterial trunk with a semilunar valve riding over a high ventricular septal defect; anatomically, only the common trunk is visible, with no vestiges of the atretic main or pulmonary arteries, and the blood supply to the body, pulmonary, and coronary circulations comes directly from the arterial trunk. The permanent arterial trunk is an extremely rare and complex congenital cardiovascular malformation. The incidence is about 0.5% and accounts for about 1 to 3% of congenital cardiovascular autopsies. Treatment Measures The procedure is performed via a median sternotomy and under extracorporeal circulation, but before blocking the aorta by extracorporeal diversion, the left and right pulmonary arteries are clamped to avoid acute pulmonary edema, and then the pulmonary artery is severed from the trunk of the artery. If the pulmonary artery has two separate openings, the two openings are cut off together with a piece of the aortic wall, and the defect in the posterior wall of the arterial trunk and the septal defect are repaired with a patch so that the arterial trunk communicates only with the left ventricle. An extravalvular catheter is applied to establish a connection between the right ventricle and the pulmonary artery. Pathological changes During the third and fourth weeks of embryonic development, the development of the arterial trunk septum separates the common arterial trunk into the ascending aorta and the main pulmonary artery under normal conditions. The arterial trunk septum grows spirally from the conus to the cephalic end, so that the ascending aorta is located posteriorly on the left and the main pulmonary artery is located anteriorly on the right, and the arterial trunk septum is connected to the conus of the conus, which participates in the formation of the membranous ventricular septum and closes the interventricular foramen. If the longitudinal septum is absent or underdeveloped, a high septal defect is formed, and the arterial trunk rides over the septal defect. The semilunar valves of the arterial trunk are often 3-valved and may have 2 to 6 leaflet malformations. The ductus arteriosus is often absent, if present at all, and is not functionally important. The pulmonary artery may exit from the root of the trunk, the main stem, or the arch, or even the pulmonary artery may not develop, and blood for the pulmonary circulation comes only from the enlarged bronchial arteries, so there can be various types of permanent arterial trunks, but regardless of the type, blood for the somatic, pulmonary, and coronary circulations comes from the ventricles and the arterial trunk. Hemodynamics: In cases of permanent arterial trunks, all blood from the left and right ventricles enters the arterial trunk. Venous blood and oxygenated blood from the pulmonary circulation ejected from the left ventricle and blood from the body circulation ejected from the right ventricle are mixed into the arterial trunk, and the degree of the resulting decrease in oxygen saturation depends on the amount of pulmonary blood flow pulmonary blood flow is more clinically insignificant or less severe cyanosis. However, heart failure is likely to occur in cases of increased cardiac load with incompatible arterial trunk valves, and pulmonary edema and cyanosis on the side of low pulmonary blood flow may occur as a result of elevated left atrial pressure, leading to reduced pulmonary blood flow. The most common cause is obstructive lesions of small pulmonary vessels in the pulmonary vascular bed that are subjected to high blood pressure from the body circulation, resulting in increased resistance to pulmonary circulation and decreased blood flow. Clinical manifestations Depending on the origin of the pulmonary artery, there are several ways of staging the permanent arterial trunk. At present, the common clinical practice is to divide it into four types according to Collect and Edwards method. 1. Type I. The arterial trunk is partially separated, and the main pulmonary artery originates from the proximal end of the arterial trunk, residing on the left side in the same plane as the ascending aorta on the right side, receiving blood from both ventricles. This type is common, accounting for about 48%. 2. Type II. The left and right pulmonary arteries open together or are close to each other, and originate from the posterior wall of the middle of the arterial trunk, accounting for about 29%. 3.Type III. The left and right pulmonary arteries originate from both sides of the arterial trunk, accounting for about 11%. Type IV pulmonary artery originates from the descending aorta of the thoracic segment or pulmonary artery is absent, and the pulmonary artery blood supply comes from the bronchial artery, accounting for about 12%.