THE BLALOCK operation1 is the anastomosis of one of the systemic arteries arising from the aortic arch to either the right or the left pulmonary artery. This may be done by either an end to side or an end to end method of suture. The operation is indicated in cases of congenital pulmonary stenosis or atresia of the pulmonary orifice.
Although pure pulmonary stenosis does occur, most children with this anomaly also have the associated defects of dextroposition of the aorta, interventricular septal defect and right ventricular enlargement. This is known as tetralogy of Fallot. The disabling factor in the malformation is the pulmonary stenosis, which prevents sufficient blood from reaching the lungs to permit normal oxygenation of the blood.
The diagnosis of pulmonary stenosis is made on the presence of noticeable cyanosis, clubbing of the fingers and toes, increased red blood cell count and the appearance of the