Cardiac surgery and perioperative care in the newborn

Chairman, Department of Pediatric and Congenital Heart Surgery,
Cleveland Clinic Foundation,
Cleveland, Ohio, USA
Roger B.B. Mee

The mortality for cardiac surgery in the newborn period remains universally higher than that for older infants and children. Open heart biventricular repair is significantly less risky than open-heart univentricular surgery or palliative closed surgery in the presence of complex intracardiac abnormalities. There are certainly theoretical reasons neonatal surgery is riskier, such as the technical problems associated with anesthesia, perfusion, surgery on small structures, the heightened inflammatory response to cardiopulmonary bypass, the deleterious effects of circulatory arrest or low flow perfusion, immaturity of neonatal organs, and the fetal myocardium's relative inability to handle volume loading.
Perioperative care
The historical combination of partial resuscitation, catheter study followed by early surgery appears to have been a harmful one. Currently resuscitation is avoidable in an increasing number. Prenatal diagnosis has reduced neonatal resuscitation. The catheter study can be almost always avoided and with improved intensive care it is possible to ensure return of all organ functions before proceeding with surgery. Customized anesthesia incorporates meticulousness, a high degree of skill placing lines, correct selection of anesthetic agents and mode of ventilation. Currently, at long last, there is an increasing movement away from use of profound hypothermia and circulatory arrest for the whole repair. Radical manipulation of systemic resistance has allowed for high flow, low pressure perfusion and there is a wider acceptance that a higher hematocrit on cardiopulmonary bypass is beneficial The customized adjustment of hematocrit for weaning from cardiopulmonary bypass is achievable through ultrafiltration during rewarming. The roles of alpha-stat and pH-stat strategies in neonates, are better understood. Until recently, hypoplastic left heart syndrome was the one condition where prolonged hypothermia and circulatory arrest seemed to be mandatory. Staged regional perfusion has emerged as a way of reducing prolonged loss of cerebral blood flow. Myocardial preservation during cross-clamp times is less well understood but clearly an important component must be respect for Starling's equilibrium in the capillaries.
  For the majority of neonatal biventricular repairs, volume loading is actually reduced. The exception to this is biventricular repair in cyanotic patients with a reduced pulmonary blood flow.
  Post-operative care has certainly matured with a much improved understanding of appropriate blood pressures, filling pressures, systemic and pulmonary resistance, hematocrits, modes of ventilation, management of the inflammatory response, calcium and glucose supplementation, of fluid restriction and methods for eliminating excessive body fluid. Placement of a peritoneal dialysis catheter at the time of surgery is extremely easy, provides the first hint of leaking capillary syndrome, is a method of eliminating excess fluid by simple drainage.
Results
For neonatal biventricular repair, 30 day mortalities have been consistently at or below 2% for the last 20 years. In the last 10 years the mortality for the Norwood procedure has been 16% and only 3% if the ascending aorta has been larger than 2.5 mm in diameter. (Sano's) Norwood operation using a right ventricular to pulmonary artery conduit is exciting and promises a further reduction in neonatal mortality for hypoplastic left heart syndrome. Similarly, regional perfusion shows promise in reducing the known cerebral damage associated with profound hypothermia and circulatory arrest traditionally used for the classical Norwood operation. This approach becomes critically important for those surgical teams with longer repair times.
  Many details in neonatal cardiac surgery can be improved. Among these are better control of the inflammatory response, increased skills in the operating room by the whole team, increased precision and timeliness of appropriate decision making in the intensive care setting and improved extramural post-operative care in the home.