Congenital heart defects: Nursing pathophysiology

Congenital heart defects, also sometimes called congenital heart disease, are a group of conditions involving structural abnormalities of the heart, great vessels, or both. They can be cyanotic or acyanotic based on the presence or absence of cyanosis, which is a blue discoloration of the skin and mucous membranes.

As a quick review, during gestation, the fetal lungs are fluid-filled and have high vascular resistance, so they don’t participate in gas exchange. Instead, blood is shunted away from the lungs, and the fetus receives oxygenated blood from the placenta, where gas exchange occurs and metabolic wastes are removed.

Now, the high vascular resistance in the lungs also causes the pressure in the right side of the heart to be much higher than the left side, so, as oxygenated blood enters the right atrium, most of the blood is shunted into the left atrium through the foramen ovale, an opening between the right and left atria. Blood then moves into the left ventricle where it’s pumped through the aortic valve, into the aorta, and out to the fetal body.

Now, some blood from the right atrium passes into the right ventricle, through the pulmonary valve and into the pulmonary artery, heading for the lungs. But before it can get to the lungs, the blood is shunted through the ductus arteriosus, a vessel connecting the pulmonary artery to the aorta. The aorta then sends the blood out to the fetal body.

Following birth, the foramen ovale and ductus arteriosus close. The pressure on the left side of the heart increases and pressure on the right side of the heart decreases as pulmonary vascular resistance lessens, and the lungs begin to participate in gas exchange. Deoxygenated blood now moves from the right side of the heart to the lungs for oxygenation and returns to the left side of the heart before being pumped to the rest of the body.