Balloon angioplasty in congenital heart disease.
Balloon angioplasty and valvuloplasty offer an alternative to surgery in many congenital cardiac conditions and are a useful adjunct in others. To yield optimal results, the most desirable improvement in hemodynamics with the least amount of damage to normal tissue, choice of the catheter should take into consideration the size of the balloon, type of shaft and shape of the balloon. Experience has shown that dilatation is best achieved when the size of the balloon is such that there is a combination of circumferential force, the stress exerted when the balloon is near its maximal diameter, and longitudinal force, the extent of which is directly proportional to the deformity of the balloon. If the balloon is too small, little benefit may be accrued from the procedure; if it is too large, there is a risk of danger to adjacent normal structures. A stiff shaft helps to maintain a stable position during inflation and the size of the shaft determines the caliber of the guidewire lumen and the inflation/deflation lumen. A single, circular balloon has the advantage of distributing the dilating forces uniformly during inflation; more recently introduced alternative designs with two or three balloons mounted around the shaft have the advantage of allowing some blood flow to occur even at full inflation but they also have the theoretical disadvantage of not ensuring an even distribution of circumferential force. Dilatation of pulmonary valve stenosis may be considered indicated in the presence of a pressure gradient of 40 mm Hg with a right ventricular pressure of 60 mm Hg as the lower limit. In the newborn, this may be qualified by setting the lower limit of right ventricular pressure as 10 mm Hg below systemic arterial pressure if that is 60 mm Hg or less. On choice of the proper balloon size, approximately 20 to 30 percent greater than the pulmonary root, success may be expected in 90% of the cases and, in general, the initial result appears to be that which persists. Although Doppler echocardiography frequently shows pulmonary regurgitation, this is rarely clinically evident. The procedure is safe and only few complications have been reported. Establishing the indication for aortic valvuloplasty usually requires the presence of a systolic gradient of 60 mm Hg without severe regurgitation; mild aortic regurgitation is not a contraindication to the procedure. Reports have indicated good results in both infants and children. This procedure is not without risk and deaths have been reported.(ABSTRACT TRUNCATED AT 400 WORDS)
Tynan
M
M
Department of Paediatric Cardiology, United Medical School, Guy's Hospital, London.
D000368:Aged; D000792:Angiography; D000800:Angioplasty, Balloon / Q000379:methods; D001017:Aortic Coarctation / Q000000981:diagnostic imaging / Q000628:therapy; D001024:Aortic Valve Stenosis / Q000000981:diagnostic imaging / Q000628:therapy; D002648:Child; D003251:Constriction, Pathologic; D006330:Heart Defects, Congenital / Q000628:therapy*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D011651:Pulmonary Artery; D011666:Pulmonary Valve Stenosis / Q000628:therapy; D012008:Recurrence