Atrioventricular Septal Defect - Causes, Symptoms, and Treatment

Introduction:

The condition referred to as atrioventricular septal defect, atrioventricular canal defect, or endocardial cushion defect is a type of congenital heart abnormality. It is characterized by the existence of an opening between the heart's chambers and issues with the valves responsible for regulating blood flow within the heart. A typical heart is composed of four chambers, consisting of two upper chambers and two lower chambers. The right and left atria, which are the upper chambers, receive incoming blood, while the right and left ventricles, which are the lower chambers, pump blood out of the heart. To ensure the proper flow of blood, there are four valves located at the openings between the chambers: the tricuspid valve, pulmonary valve, mitral valve, and aortic valve. These valves act as gates, directing the blood in the correct direction. Among all congenital heart diseases, the atrioventricular septal defect has a prevalence of three percent.

What Is an Atrioventricular Septal Defect?

An atrioventricular septal defect is a heart defect in which there is a hole on the right and left side walls separating the atrium and ventricle of the heart. The valves that control the blood flow between these chambers may not be formed correctly. In an atrioventricular septal defect, the blood flows where it normally should not go. The blood can have less than a normal amount of oxygen, and extra blood can flow to the lungs forcing the heart and lungs to work harder. This may lead to congestive heart failure.

What Are the Types of Atrioventricular Septal Defects?

1. Complete Atrioventricular Septal Defect - This condition occurs when there is a significant opening in the center of the heart, enabling blood to circulate freely among all four chambers. It typically manifests at the juncture where the normal partitions (septa) between the two atria and two ventricles intersect. It commonly develops during pregnancy.

2. Partial Atrioventricular Septal Defect - It occurs when the heart defect involves two chambers, unlike a complete atrioventricular septal defect where all four chambers are involved. It usually has both tricuspid and mitral valves, but one of them may not close completely, allowing the blood to leak backward from the ventricle to the atrium.

What Is the Cause of Atrioventricular Septal Defect?

The atrioventricular septal defect occurs before birth when the heart of the fetus is developing. The exact cause of the atrioventricular septal defect is not known. In most cases, this defect is caused by genetic mutations and is often associated with syndromes. The chances of it increase in a person with Down syndrome.

What Are the Signs and Symptoms of Atrioventricular Septal Defect?

Signs and symptoms of complete atrioventricular septal defect:

• Wheezing.

• Difficulty breathing.

• Fatigue.

• Poor weight gain.

• Pain skin color.

• Lack of appetite.

• Rapid or irregular heartbeat.

• Bluish discoloration of skin and lips.

• Excessive sweating.

• Swollen legs, ankles, and feet.

Signs and symptoms of partial atrioventricular septal defect:

• Arrhythmia (abnormal heartbeat).

• Shortness of breath.

• Pulmonary hypertension (high blood pressure in lungs).

• Problems with the heart valve.

• Heart failure.

How to Diagnose Atrioventricular Septal Defects?

Ultrasound and specialized heart imaging can be utilized to diagnose atrioventricular septal defects prior to the baby's birth. When the baby's heart is listened to by the doctor after birth, they might detect an unusual rushing noise (known as a heart murmur). If the baby is showing the signs and symptoms of this defect, the following tests are recommended:

• Echocardiogram - Utilizing sound waves, this examination generates moving images of the heart, allowing for the identification of irregular heart valves, cardiac defects such as a hole in the heart, and anomalies in blood circulation within the heart.

• Electrocardiogram - In this test, electrical signals are recorded while traveling through the heart. The pattern of the electrical signals shows normal or abnormal heart function.

• Chest X-ray - This is done to check for the size of the heart. It is helpful to detect an enlarged heart.

• Cardiac Catheterization - This procedure entails the insertion of a flexible and thin tube called a catheter into a blood vessel located in the groin area, which is then advanced up to the heart. By injecting a dye through the catheter, the heart's structures become more visible on X-rays, enabling clearer visualization. Moreover, this test permits the measurement of pressure within the heart's blood vessels and chambers.

What Are the Treatment Options for the Atrioventricular Septal Defect?

• Medical Treatment - Vasodilators and diuretics are given to reduce the preload and afterload in order to reduce the symptoms of pulmonary congestion and heart failure. Feeding problems and failure to thrive are managed by feeding tubes and providing extra calories. Medical treatment is often directed toward optimizing the condition of the patient for the surgery.

• Surgical Treatment - The ultimate treatment of the atrioventricular septal defect is surgical correction. For both complete and partial defects, surgery is recommended. Often more than one surgery is needed. The surgery to correct the defect involves using one or two patches to close the hole in the wall of the heart. The patches become a part of the heart’s wall as they stay there permanently. Other surgeries depend on what other heart problems are present and whether the defect is complete or partial. For partial atrioventricular septal defect, mitral valve repair surgery is needed, and if repair is impossible, valve replacement surgery is done. For a complete atrioventricular septal defect, doctors separate the single abnormal valve between the heart chambers into two valves. If separation of the single valve is not possible, heart valve replacement of both the mitral and tricuspid valves is done.

What Are the Complications of Atrioventricular Septal Defect?

• Heart Enlargement - The heart becomes larger when it is forced to work hard because of the increased blood flow.

• Pulmonary Hypertension - A hole in the heart allows the mixing of oxygenated and deoxygenated blood resulting in an increased amount of blood going to the lungs. This leads to pressure build-up in the lungs.

• Respiratory Tract Infections - A person suffering from an atrioventricular septal defect is prone to have repeated lung infections.

• Heart Failure - An untreated atrioventricular septal defect often makes the heart incapable of pumping enough blood to meet the body’s demands.

Conclusion:

An atrioventricular septal defect is a congenital heart malformation involving the chambers and valves of the heart. The treatment usually improves the outlook for children with atrioventricular septal defects. However, some who had surgery may develop heart problems such as leaky heart valves, narrowing of heart valves, breathing problems, and abnormal heart rhythm when they grow up. While each situation varies, numerous children diagnosed with congenital heart defects often progress into adulthood with a healthy quality of life.