Ventricular Septal Defect (VSD)

Ventricular Septal Defect is an acyanotic heart defect causing a hole in the septum between the left and right ventricles.

• Blood will shunt from the left ventricle to the right, as it shunts to the side with the least resistance.   The amount of shunting depends on the size of the hole and the degree of pulmonary vascular resistance.
• After 1-2 weeks of life, the pulmonary vascular resistance would have decreased.  At this point, a large amount of blood will shunt from left to right.
• The shunted blood travels out of the right ventricle into the pulmonary artery.  This causes the pulmonary artery, left atrium and left ventricle to enlarge due to the additional blood flow.
• Left ventricle hypertrophy occurs to effectively pump the additional blood around the body.
• The excess blood going to the lungs causes pulmonary over circulation, which causes most of the symptoms.
• Over a period of time, the blood vessels in the lungs change due to increased blood flow.  The muscle layer in the artery walls thickens and reduces the size of the vascular lumen. The decreased size in the lumen increases resistance to blood flow.
• If the resistance is majorly increased the changes can become irreversible, and pulmonary vascular resistance will continue to rise.

• Tachycardia - Heart rate will increase due to lack of oxygen in the blood, causing the body to try and pump blood more quickly.
• Tachypnea - Due to decreased oxygen in the blood, the respiratory rate will increase to increase oxygen intake.
  
• Failure to Gain Weight - Due to having problems with feeding.
• Hypoxemia - Can cause low saturations as there is less oxygen in the blood due to less oxygenated blood being pumped around the body.

The repair depends on the size and area of the septum involved.

• Cardiac Catheter Device Closure - A catheter is inserted into a vein in the groin and passed up to the heart.  The device is inside a sheath which is then pushed into the catheter and passed to the heart.  X-ray and transoesophageal echocardiogram are used to ensure the device is in the correct place.  Once the device is in place, the device opens either side of the hole to close it off, and the catheter is removed.
  
• Open Heart Surgery - The surgeon will make an incision into the chest and depending on the size of the hole, it will either be covered with a patch or will be closed with stitches.