stenosis, techniques include commissurotomy, valvoplasty, cordal fenestration, and splitting of papillary muscles For mitral insufficiency, techniques include repair of clefts, resection, shortening or augmentation of leaflets, cordal shortening, annuloplasty, and creation of a double orifice.161 In general, mortality is low with repair in the setting of biventricular circulations.161–164 In those with a functionally univentricular circulation, in contrast, repair carries a higher mortality.158 Repair of the aortic valve is less well accepted than that of the mitral valve, albeit experience is accumulating.165–171 Over the last decade, experience and success with repair have improved.169–172 Techniques include repair of valvar perforations, suspension of prolapsed leaflets, annuloplasty, and extension of leaflets with pericardium.158 In particular, extension of the leaflets has been used with success in patients with rheumatic aortic valve disease, with 90% of patients free from valvar related complications at 7 years Extension has also been applied to patients with congenital pathology with improving results.173,174 More contemporary approaches to aortic valve repair include the Ozaki technique This approach relies on the use of autologous pericardium to construct a stentless bioprosthetic valve in the operating room after excision of the native aortic valve It has been applied to a wide variety of aortic valve morphology In a series of over 400 reconstructions, the freedom from reoperation was 96.2% at 4 years of follow-up, and the mean residual gradient was 13.8 ± 3.5 mm Hg.175 Strategies for Cardiopulmonary Bypass and Perfusion Surgical intervention inside the heart or on the great vessels normally requires significant interruption of flow of blood in regions of the surgical field to achieve adequate visualization (Video 16.1) To permit a more controlled surgical approach, extracorporeal circulation and gas exchange was developed and first used successfully in the early 1950s.176,177 During CPB, venous blood from the great veins or right atrium is diverted to an artificial lung and then reinfused into systemic artery, most commonly the aorta A variety of specific techniques are used for cannulation and perfusion These are intended to deliver blood from which carbon dioxide has been removed and oxygen added into the patient at a rate sufficient to fully support the function of the bodily organs for the duration of the surgical repair Such techniques have permitted the development of extraordinary surgical reconstructive procedures Optimal strategy permits extensive surgical intervention, with largely predictable freedom from permanent injury to the organs Planned and unplanned modifications of techniques, however, may place organs at the risk of ischemia.178,179 Additionally, the nature of the interactions of blood with artificial surfaces, the effects of associated alterations in temperature, and nonpulsatile perfusion during bypass make the technique a pathway for direct inflammatory and ischemic injury.180 Circuitry of Cardiopulmonary Bypass One task of the perfusionist is to tailor the CPB circuit to the specific needs of the individual patient The variability of size, anatomy, and pathophysiology necessitates the use of a great number of products Large extracorporeal surface areas and prime volumes have been identified as potential contributors to complications following CPB.181 Multiple sizes of oxygenators, heat exchangers, reservoirs, and other components have been designed to address these issues Much of the research and development for the child has focused on reduction in surface area, prime volume, and biologic incompatibility.182,183 It is advisable for the circuits at a given institution to be organized in the same manner, facilitating the ability of perfusionists to provide safe and consistent service to all patients A common configuration for bypass is to use bicaval cannulation with a single venous line for drainage into a hard-shell venous reservoir with an integrated cardiotomy reservoir (Fig 16.13) A typical strategy for a cardiac cannulation is shown in Fig 16.14 A roller pump is used to pump deoxygenated blood from the reservoir through a hollow fiber oxygenator with an integrated heat exchanger and filter Blood exiting the oxygenator returns to the patient via the arterial cannula placed in the ascending aorta FIG 16.13 Simplified schematic of the components of a typical cardiopulmonary bypass circuit A roller pump, an oxygenator, a heat exchanger, a venous reservoir, and a filter are included IVC, Inferior caval vein; SVC, superior caval vein