General Anatomy/Tetralogy of Fallot
Tetralogy of Fallot includes a Large Ventricular Septal Defect (VSD), the aorta overrides left and right ventricles, right ventricular outflow tract is obstructed, and the wall of the right ventricle thickens. More blood shunts through the VSD to the left side as the obstruction impedes the RV outflow, resulting in Cyanosis; Tetralogy of Fallot has four key features. A Ventricular Septal Defect (a hole between the ventricles) and many levels of obstruction from the right ventricle to the lungs (Pulmonary Stenosis) are the most important. Also, the Aorta (major artery from the heart to the body) lies directly over the Ventricular Septal Defect, and the right ventricle develops thickened muscle.”
Adults with Tetralogy of Fallot suffer shortness of breath and can’t tolerate exercise. Brain abscesses, strokes and heart infections can arise as complications. Tetralogy of Fallot patient’s fingers may have "clubbing" which is enlargements at the distal ends. If Tetralogy of Fallot remains uncorrected, most patients die in childhood.
Diagnosis is made with Echocardiography; the VSD can be visualized with Color Doppler, and the diagnosis can be confirmed with Heart Catherterization.
Surgical repair improves survival and helps relieve symptoms. Patients should receive antibiotics before dental work or surgery.
“Even with repair these patients have a poorer survival rate… Patients with repaired tetralogy of Fallot often have atrial fibrillation or flutter, which may cause considerable morbidity.”
Pulmonary regurgitation may develop; it can be tolerated for long periods, but then the right ventricle enlarges and malfunctions, and a replacement pulmonary valve may be needed.
Some patients have recurring obstruction of the outflow tract in the right ventricle, and need repeated surgery. Large residual ventricular septal defects may require repeated surgery in 10 to 20 percent of patients. After repair of tetralogy of Fallot, Right bundle branch block patterns (RBBB) is common,  apparently increasing the chances of death. However, sometimes the first surgery is successful.
Survival is better among patients who had the surgery young. “Left and right ventricular failure due to right ventricular overload or left ventricular volume overload is another important cause of late death in older patients.”
Patients who had the surgery as adolescents or adults may have greater difficulty with exercise.