Andersons pediatric cardiology 1845

patency, the duct is ligated The main pulmonary artery can be banded with a variety of material including ePTFE, polyester tape, or silk The aorta is separated from the pulmonary artery and the tape passed around the main pulmonary artery The length of band can be estimated according to the Trusler rule The length of the band should be 20 mm plus the number of millimeters corresponding to the child's weight in kilograms.77 Neonates with transposition physiology will be more cyanotic due to unfavorable streaming In this case the length should be 24 mm plus the child's weight to prevent excessive hypoxemia.77 Arterial saturation and pressure in the distal pulmonary artery should be monitored during banding The patient should be placed on an FiO2 of 50% to decrease the amount of dissolved oxygen The band should be adjusted to achieve a distal pulmonary artery pressure of 15 to 20 mm Hg or one-fourth of the systolic blood pressure The saturation should be 80% to 85% A common technique is to use hemoclips to make the final adjustments This allows the band to be tightened and loosened in 1-mm increments The final adjustment is commonly a compromise between achieving a satisfactory pressure and avoiding excessive hypoxemia Once the proper tightness is achieved, the band is secured with multiple sutures between the band and the pulmonary artery Ideally the band should be above the sinotubular junction of the pulmonary valve and not impinging on the origin of either pulmonary artery If it is not properly secured, the band can slip and compromise the origin of a pulmonary artery, typically the right pulmonary artery, and result in excessive hypoxemia If the band is positioned too far proximally, it can encroach on the pulmonary valve and result in leaflet damage, which can cause regurgitation Restricted or Duct-Dependent Systemic Blood Flow Obstruction to systemic flow can occur due to arch hypoplasia with coarctation, aortic valve stenosis, subaortic stenosis, or a combination of these lesions These newborns will be maintained on prostaglandin to maintain systemic output Creation of unobstructed systemic outflow is important to maintain cardiac output and prevent hypertrophy of the ventricle, which would compromise future palliation Patients with fUVH and obstructed systemic blood flow will also have unobstructed pulmonary blood flow, and relief of systemic outflow obstruction must be combined with restriction of pulmonary blood flow Decision Making For isolated coarctation with or without arch hypoplasia and without additional left ventricular outflow tract obstruction (aortic valvar or subaortic stenosis), standard coarctation repair can be performed (see also Chapter 45) If the arch hypoplasia is distal to the origin of the left carotid artery, the arch can be approached via a left thoracotomy If there is proximal arch hypoplasia, an approach via a median sternotomy using cardiopulmonary bypass will be necessary.78 The procedure can be combined with pulmonary artery banding In certain groups of fUVHs with a dominant left ventricle and discordant ventriculoarterial connections, the aorta can arise from a rudimentary outflow chamber or right ventricle and connect to the left ventricle via an interventricular communication A restrictive interventricular communication will result in systemic outflow tract obstruction When the interventricular communication is small at birth, aortic hypoplasia—frequently with coarctation and occasionally with an interrupted aortic arch—may be present Even when the interventricular communication is nonrestrictive at birth, it can become narrow over time, resulting in obstruction, and the tendency for systemic outflow obstruction to progress after pulmonary artery banding has been well recognized.79,80 Strategies to prevent development of outflow tract obstruction or manage its presence include an anastomosis between the pulmonary root and the ascending aorta—the Damus-Kaye-Stansel (DKS) procedure simultaneously described by Paul Damus, Michael Kaye, and Horace Stansel in the 1970s (Fig 71.4).81–85 The anastomosis of the pulmonary root and aorta bypasses the restrictive interventricular communication A direct approach at enlargement of the interventricular communication is challenging in the neonate and risks injury to the conduction system with resultant complete heart block.86 FIG 71.4 Examples of the Damus-Kaye-Stansel (DKS) procedure for the relief of systemic outflow obstruction in the setting of a dominant left ventricle with transposed great vessels and the aorta (Ao) arising from the rudimentary right ventricle (rv, RV) (A) Diagram showing a DKS for tricuspid atresia with transposition (B) DKS in a patient with double-inlet left ventricle with L-looped ventricles LV, Left ventricle; PA, pulmonary artery; PT, Pulmonary trunk (A, From Yoo SJ, Caldarone CA Glossary of paediatric cardiovascular surgical procedures In: Yoo SJ, Babyn P, MacDonald C, eds Chest Radiographic Interpretation in Pediatric Cardiac Patients New York: Thieme; 2010:41–54 B, From Gates RN, Laks H, Elami A, et al Damus-Stansel-Kaye procedure: current indications and results Ann Thorac Surg 1993;56:111–119.) A DKS procedure requires cardiopulmonary bypass; therefore coarctation repair with pulmonary artery banding offers the newborn a less morbid procedure In the current era, where a bidirectional superior cavopulmonary anastomosis is generally performed during infancy, an interventricular communication area greater than 1 to 2 cm2/m2 (corresponding to a interventricular communication diameter of 7 mm or greater) is a reasonable cutoff identifying those patients who are unlikely to develop obstruction during infancy prior to a superior cavopulmonary anastomosis In these patients, arch repair and pulmonary artery banding can be considered for neonatal palliation and a more definitive procedure to prevent systemic ventricular outflow obstruction can be part of the second-stage palliation.87,88 More severe forms of systemic ventricular outflow tract obstruction are frequently associated with coarctation and arch hypoplasia This includes more severe forms of fUVH with a dominant left ventricle and discordant ventriculoarterial connection (tricuspid atresia with transposed great vessels), and those with dominant right ventricle and concordant ventriculoarterial ... paediatric cardiovascular surgical procedures In: Yoo SJ, Babyn P, MacDonald C, eds Chest Radiographic Interpretation in Pediatric Cardiac Patients New York: Thieme; 2010:41–54 B, From Gates RN, Laks H, Elami A, et al