Tetralogy of Fallot is the most common cyanotic con genital in adults and may present to the physician before or, more commonly, after corrective or liative.
The tetralogy has four components, which include right ventricular outflow obstruction secondary to pulmonic valve or infundibular stenosis, membranous VSD, overriding aorta across the VSD is usually large and allows blood flow to usually large and allows blood flow to be shunted from the right ventricle to the systemic on The degree right-to-left shunt flow depends the degree of right ventricular outflow obstruction.
If pulmonic stenosis is mild, right-to-left shunt flow is min the patient remains acyanotic (pink tetralogy). More commonly, the pulmonic stenosis is severe, and a large volume of poorly oxygenated blood is shunted into the systemic circulation, with resulting cyanosis. The degree of cyanosis is worsened with exercise, when the fall in systemic vascular resistance increases the degree of right-to-left shunt flow. Complications of tetralogy include severe erythrocytosis, paradoxical emboli, bacterial endocarditis, and ventricular arrhythmias, Surgical correction of tetralogy is usually performed during infancy or childhood and involves relief of right ventricular obstruction and patch closure of the VSD.
In patients surviving to adulthood corrective surgery should still be undertaken, but the higher secondary to the presence of operative risk is higher secondary to the presence of right ventricular dysfunction. Palliative surgery involves the certain of a shunt between the systemic and pulmonary circulation.