The four chambers of the heart are the right and left atria and the right and left ventricles.

The heart has four valves:

tricuspid valve

mitral valve

aortic valve

pulmonic valve.

Blood enters the right atrium from the inferior and superior vena cavae and then goes into the right ventricle. From there, it’s pumped into the pulmonary artery to the lungs, where it gains oxygen and loses carbon dioxide.

The pulmonary veins bring the oxygenated blood from the lungs to the left atrium. The oxygenated blood then passes into the left ventricle, is pumped into the aorta, and is delivered to the rest of the body via the arteries. Arteries are large, thick-walled blood vessels that distribute oxygenated blood to the capillaries.

The pulmonary artery is the only artery in the body that carries deoxygenated blood. The pulmonary veins are the only veins in the body that carry oxygenated blood.

To maintain homeostasis, the body will make many adjustments to the factors that contribute to cardiac output.

In the fetus, the lungs are filled with fluid and aren’t yet the site of gas exchange. The amount of blood that passes through the lungs is just enough to perfuse lung tissue.

At birth, however, the neonate must transition from a reliance on the placenta to a reliance on his lungs for oxygenation. This transition is normally accomplished within the first few breaths after birth.

Key structures that maintain fetal circulation include:

Cardiac adaptations at birth occur gradually, resulting from structural and pressure changes in the lungs, heart, and major vessels. With the first few breaths after birth, the fluid in the neonate’s lungs is absorbed and replaced with air. Inspired oxygen dilates the pulmonary vessels, resulting in decreased pulmonary vascular resistance and increased pulmonary blood flow as the lungs fill with air and expand. More blood will now travel to and from the lungs.

The pressure in the right atrium, right ventricle, and pulmonary artery decreases. Simultaneously, a gradual increase in systemic vascular resistance occurs when the umbilical cord is clamped and the low-resistance placental circulation is removed. At that point, left atrial pressure increases more than right atrial pressure. The foramen ovale, which was a one-way door, closes as a result of this unequal pressure. The ductus arteriosus begins to close because of increased pulmonary blood flow and the dramatic reduction in pulmonary vascular resistance. Later, the ductus arteriosus (and ductus venosus) will become ligaments and will be closed structurally.

Function of the foramen ovale ceases immediately or soon after birth. Ductus arteriosus functioning ceases after the infant is about 4 days old. Anatomic closure, however, takes considerably longer. If the foramen ovale or ductus arteriosus fails to close, persistent shunting of fetal blood away from lungs will result. (See From fetal to neonatal circulation, page 270.)

When auscultating for murmurs, position the child in the sitting and reclining positions. Also, auscultate the heart with the child standing, sitting and leaning forward, and in a left side-lying position. (See Grading murmurs.)

Transesophageal echocardiography (TEE) combines ultrasound with endoscopy. It’s an alternative method for detecting cardiovascular problems in children and is used when the transthoracic approach isn’t possible or would be difficult. During the procedure, the transducer is passed into the esophagus to an area behind the atria. The procedure is more complicated than the transthoracic approach and may require sedation and intubation to preserve the airway in young children.

Explain the procedure to the child and his parents; tell the child what he’ll see, hear, and feel and be honest about any pain or discomfort he might experience. In addition, follow these steps:

Explain the test to the child and his parents, stressing that there’s no pain involved. In addition:

When explaining the test to the child, show him a picture of the scanner or, whenever possible, let the child see the actual scanner. Tell the child that no pain is involved; prepare him if contrast media must be used. In addition:

Most children know what a bicycle looks like, but they may not be familiar with the concept of a stationary bike. They may not recognize a treadmill at all. So, good instructions and explanations may be necessary. Pictures or other visual aids may be helpful. Let the child know that there will be monitoring equipment, which may contain several wires that may be attached to him or her. Assure the child that there is no pain involved. In addition:

Nursing interventions focus on monitoring and educating the patient and his parents.

Cardiac catheterization is used to evaluate ventricular function and measure heart chamber pressures and oxygen saturation in the blood. It also serves as a method for obtaining cardiac muscle biopsy specimens and for performing electrophysiologic studies.

Nursing interventions for cardiac catheterization begin when the procedure is scheduled and continue throughout the recovery period.

Cardiopulmonary bypass machines are typically used to oxygenate body tissues because surgery may necessitate stopping the heart. During the procedure, the patient is placed in a hypothermic state to minimize blood loss (which enhances patient recovery) and to reduce the body’s need for oxygen. An incision into the chest (thoracotomy) is commonly performed, and chest tubes are placed.

Prepare the child (and his parents) for what he’ll see, hear, and feel after surgery. When a child and his parents know ahead of time that certain events are “normal,” those events will be less stressful and frightening when they occur.

There are two surgical options for cardiac transplantation:

The process begins by placing the child on the United Network for Organ Sharing (UNOS) list to match a donor with the recipient. Due to limited donor supply, 30% of infants on the UNOS list die before a new heart can be found for them. Approximately 300 to 400 transplants are performed per year on pediatric patients.

Complications are most common during the first 6 months to 1 year after transplantation. During this period, the family must adjust to a totally new lifestyle that will require lifelong management. The leading cause of demise after heart transplantation is organ rejection. Because lifelong immunosuppressive therapy is required, infection is always a risk.

The child and his parents must be prepared thoroughly for this major procedure. Preparation should include a brief visit to the coronary intensive care unit (CICU) and, if possible, the child should be introduced to the nurses who will be providing his care. Parents should be made aware of the visiting policies in the CICU and should be assisted in making arrangements (in the hospital and at home) to spend as much time with their child as possible.

The three types of ASDs are:

ostium secundum defect, the most common type, which occurs in the region of the fossa ovalis at the center of the atrial septum and, occasionally, extends inferiorly, close to the vena cava

sinus venosus defect, which occurs in the superior-posterior portion of the atrial septum, sometimes extends into the vena cava,
and is almost always associated with abnormal drainage of pulmonary veins into the right atrium

ostium primum defect, which occurs in the inferior portion of the septum primum and is usually associated with AV valve abnormalities (cleft mitral valve) and conduction defects.

ASD accounts for about 10% of congenital heart defects and is almost twice as common in females as in males, with a strong familial tendency. Although an ASD is usually a benign defect during infancy and childhood, delayed development of symptoms and complications makes it one of the most common congenital heart defects diagnosed in adults.

The prognosis is excellent for asymptomatic patients and for those with uncomplicated surgical repair. The prognosis is poor, however, in patients with cyanosis caused by large, untreated defects.

The cause of ASD is unknown. Ostium primum defects commonly occur in patients with Down syndrome.

In ASD, blood shunts from the left atrium to the right atrium because the left atrial pressure is normally slightly higher than the right atrial pressure. The difference in pressure forces large amounts of blood through the defect. This shunt results in right heart volume overload, affecting the right atrium, right ventricle, and pulmonary arteries.

Signs and symptoms of ASD include: