Patent Ductus Arteriosus

What is Patent Ductus Arteriosus?

The ductus arteriosus is a blood vessel that connects the pulmonary artery to the descending aorta during fetal development. Normally, the ductus closes within days or weeks after birth. Its closure routes oxygenated blood to the body and unoxygenated blood to the lungs.

In patent ductus arteriosus, the lumen of the ductus remains open after birth.This abnormal opening allows blood to shunt left to right from the aorta to the pulmonary artery. The result is recirculation of oxygenated arterial blood through the lungs.

The amount of blood shunted through the ductus, depends on the relative resistances of pulmonary and systemic vasculature and on the size of the ductus itself. The left atrium and left ventricle must accommodate increased pulmonary venous return, which increases the left ventricular filling pressure and work load and could lead to left-sided heart failure.

Patent ductus arteriosus typically affects twice as many females as males. When it occurs with rubella, however, it affects both sexes in equal numbers. It is the most common congenital heart defect in adults; ,symptoms of pulmonary vascular disease appear by age 40. The prognosis is good if the shunt is small or can be surgically repaired.

Causes of Patent Ductus Arteriosus ?

Failure of the ductus to close - most prevalent in premature infants and those born at high altitudes probably stems from abnormal oxygenation or from the relaxant action of prostaglandin E, which prevents the ductal spasm and contracture needed for closure. Patent ductus arteriosus may be familial or have no known cause. It commonly accompanies rubella syndroome and may be associated with other congenital defects, such as coarctation of the aorta, a ventricular septal defect, and pulmonic and aortic stenoses.

Signs & Symptoms of Patent Ductus Arteriosus

• poor feeding habits
• shortness of breath

A child with a small patent ductus arteriosus might not have any symptoms, and your child's physician may have only noted the defect by hearing a heart murmur. Other infants with a larger PDA may exhibit different symptoms.

Diagnostic Tests

Chest X-rays show increased pulmonary vascular markings, prominent pulmonary arteries, and enlargement of the left ventricle and the aorta. Results vary with the size of the shunt.

Electrocardiography (ECG) results may be normal or may indicate left ventricular hypertrophy, left atrial enlargement and, in pulmonary vascular disease, biventricular hypertrophy.

Echocardiography can be used to detect and estimate the size of a shunt. It also reveals an enlarged left atrium and left ventricle, or right ventricular hypertrophy from pulmonary vascular disease.

Cardiac catheterization - a procedure that gives very detailed information about the structures inside the heart. Under sedation, a small, thin, flexible tube (catheter) is inserted into a blood vessel in the groin, and guided to the inside of the heart. Blood pressure and oxygen measurements are taken in the four chambers of the heart, as well as the pulmonary artery and aorta. Contrast dye is also injected to more clearly visualize the structures inside the heart.

Treatment

Asymptomatic infants require no immediate treatment. Those with left-sided heart failure require fluid restriction. diuretics, and digitalis glycosides until surgery can be performed. If signs and symptoms are mild, surgical correction is usually delayed until the infant is 1 year old. Before surgery, the child requires antibiotics to protect against infective endocarditis. Experimental treatments include cardiac catheterization to deposit a plug or umbrella in the ductus, or administration of indomethacin I.V. to induce the ductus to spasm and close.

Prevention Tips

In most cases, you can't do anything to prevent having a baby with a heart defect. However, it's important to do everything possible to have a healthy pregnancy. Here are the basics:

• Exercise regularly
• Keep diabetes under control
• Eat a well-balanced diet
• Avoid alcohol, cigarettes and illicit drugs.