Ventricular Septal Defect: Causes, Diagnosis, and Treatment

Ventricular septal defects (VSDs) are the most prevalent congenital cardiac anomaly in children and the second most common heart defect in adults, after bicuspid aortic valves. The primary mechanism of hemodynamic compromise in VSDs arises from abnormal communication between the right and left ventricles, leading to shunt formation. VSDs can be congenital or acquired, with the latter often referred to as ventricular septal rupture, which occurs spontaneously and is associated with severe ischemic or inflammatory conditions. Many small VSDs close spontaneously within the first year of life, and asymptomatic cases often require no intervention. 

What are the causes of VSD?

VSDs result from developmental abnormalities or disruptions in the formation of the interventricular septum during the complex process of embryological heart morphogenesis. VSD may co-exist with conditions such as atrial septal defects, patent ductus arteriosus, right aortic arch, pulmonic stenosis, aortic coarctation, subaortic stenosis, tetralogy of Fallot, and transposition of the great arteries, adding to the complexities of congenital heart disease. 

The causes of VSD may include:

• Maternal infections
• Maternal diabetes
• Phenylketonuria 
• Maternal exposure to toxins such as alcohol, marijuana, cocaine, and certain medications, including metronidazole and ibuprofen, is also linked to VSDs.
• Genetic factors such as chromosomal abnormalities, single-gene mutations, and polygenic inheritance. 
• Recent epidemiological studies have revealed that maternal epilepsy, migraines, chronic hypertension, and paroxysmal supraventricular tachycardia may be associated with an elevated risk of VSDs. [1] 

What are the types of VSD?

Based on their location and structure of the defect, VSDs are classified as:

• Membranous: This is the most common type of VSD seen in the upper section of the wall between your ventricles.
• Muscular: There may be more than one hole located in the lower part of the interventricular septum. 
• Inlet: This is a hole just below the tricuspid valve in your right ventricle and the mitral valve in your left ventricle. When blood enters your ventricles, it must pass through a VSD that connects them.
• Outlet: This kind of VSD creates a hole just before the pulmonary valve in your right ventricle and just before the aortic valve in your left ventricle. Blood has to go by the VSD on its way through both valves. 

What are the symptoms of VSD? 

Infants born with VSD may exhibit the following symptoms:

• Shortness of breath, including fast breathing or struggling to breathe.
• Sweatiness or fatigue during feeding
• Slow weight gain
• Frequent respiratory infections
• A VSD heart defect in older children and adults can make them feel tired or out of breath during physical activity.
• Bluish discoloration of skin, tongue, or fingernail beds 

Symptoms of VSD may go unnoticed if the hole is less than 3 millimeters. A VSD that’s moderate (3 to 5 mm around) to large (6 to 10 mm around or about the size of a pea) may cause symptoms. [2]

How is VSD diagnosed?

Tests that help diagnose VSD include: 

• Echocardiogram 
• Electrocardiogram
• Chest X-ray: To check heart enlargement or lung infiltration 
• Pulse oximetry: To check peripheral tissue oxygenation
• Cardiac catheterization
• Cardiac Magnetic resonance imaging (MRI) scan
• Cardiac computerized tomography (CT) scan

How are VSDs treated? 

Ventricular septal defect treatment may include regular health checkups, medications, and surgery. 

• Medications cannot repair the VSD, but can help manage symptoms. Water pills (diuretics) are used to decrease the amount of fluid in the body and reduce the strain on the heart. Supplemental oxygen may help mitigate the effects of hypoxia.
• Surgeries and procedures to repair a ventricular septal defect include:
  • Open heart surgery
  • Catheter procedure (relatively less invasive) 
  • Regular follow-up for check-ups is needed after any treatment of VSD. [3]

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