Chapter 131. Malformations of The Cardiovascular System - Review of Medical Embryology Book

PATENT DUCTUS ARTERIOSUS is 2 to 3 times more common in the female than in the male. Is due to a failure of the distal part of the left sixth aortic arch to involute after birth and become ligamentous
COARCTATION OF THE AORTA: common; a narrowing of the aorta either below or above the ductus arteriosus. May occur directly opposite the ductus, but usually is classified into 2 types

Preductal type: less common; constriction is above the level of the ductus. The ductus usually stays open, and a communication exists between the descending aorta and the pulmonary artery
Postductal type: common; constriction is below the level of the ductus. The latter is usually closed and forms a ligament. Condition permits collateral circulation in the fetal period and helps circulation in lower parts of the body

DOUBLE AORTIC ARCH: rare; characterized by a vascular ring that compresses the trachea and esophagus. Due to failure of involution of distal part of the right dorsal aorta. Both a right and left aortic arch arise from the ascending aorta
RIGHT AORTIC ARCH: the entire right dorsal aorta persists, and the distal segment of the left dorsal aorta involutes. Two types are described

Right aortic arch without a retroesophageal component: the ductus (ligamentous) arteriosus passes from the right pulmonary artery to the right aortic arch. No vascular rin It is usually asymptomatic, but other cardiac defects are seen
Right aortic arch with retroesophageal component: the right aortic arch is behind the esophagus. The normal left ductus arteriosus (ligamentum arteriosum) attaches to the descending aorta and forms a vascular ring that may constrict the trachea and esophagus

ABNORMAL ORIGIN OF THE RIGHT SUBCLAVIAN ARTERY (retroesophageal subclavian): the right subclavian artery arises from the ascending aorta and passes behind the trachea and esophagus to the right arm

Is the result of the right fourth aortic arch and right dorsal aorta involuting cranial to the seventh intersegmental artery. The right subclavian forms from the right seventh intersegemental artery and distal part of the right dorsal aorta

DOUBLE SUPERIOR VENA CAVA (persistent left superior vena cava): due to an absence of or inadequate anastomosis between the anterior cardinal veins, resulting in the left anterior cardinal vein persisting as part of the left superior vena cava

The abnormal left superior vena cava may open into the coronary sinus or, less commonly, into the left atrium

Total: none of the pulmonary veins connects with the left atrium, but they connect to the right atrium or to one of the systemic veins or both
Partial: One or more (not all) of the pulmonary veins have anomalous connections. Others enter the left atrium of the heart normally

DOUBLE INFERIOR VENA CAVA AT THE LUMBAR REGION: the left sacrocardinal vein has failed to lose its connection with the left subcardinal, and the left common iliac vein may or may not be present. The left gonadal vein is normal
ABSENCE OF THE INFERIOR VENA CAVA: the right subcardinal vein fails to make connection with the liver and shunts its blood to the right supracardinal vein. Blood from the caudal part of the body reaches the heart via the azygos and superior vena cava, and the hepatic vein enters the right atrium at the site of the inferior vena cava
LEFT SUPERIOR VENA CAVA: persistence of left anterior cardinal vein and obliteration of common cardinal and proximal part of anterior cardinal vein on the right. Blood from the right is channeled to the left by the brachiocephalic vein