These analyses indicate that early failure has declined over the study period and that this decline is related in part to procedural modifications. A continuing late hazard phase is associated with few patient-related variables and does not appear related to procedural variables.

Reparative operations for insufficient cardiac valves constitute the surgical procedures of choice when pathoanatomies permit. At present, mitral and tricuspid repair techniques are well-established, but recent data also suggest that reconstruction of insufficient aortic valves may be associated with lower operative mortality, fewer valve-related complications, and improved survival. In an effort to increase adoption of aortic valve repair and to mitigate recurrent insufficiency, annuloplasty rings based on normal aortic root geometry have been developed to position in the inflow portion of the aortic annulus similar to mitral and tricuspid rings. This review will describe techniques for tri-leaflet and bicuspid geometric ring annuloplasty, and also will address leaflet reconstruction methods for the common leaflet pathologies. The application of a pathoanatomic approach to aortic insufficiency now permits the majority of aortic valves to be repaired with acceptable clinical outcomes.

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Although a patent ductus arteriosus (PDA) increases fluid and protein efflux from the pulmonary vasculature in preterm infants (1, 2), a compensatory increase in pulmonary lymph flow appears to prevent pulmonary edema during the first 72 h after delivery in both premature animals (3, 4) and humans (5). However, a symptomatic left-to-right ductus shunt that persists beyond the first week of life increases the likelihood of edema formation and respiratory compromise. Several studies (performed in the presurfactant era) found that, by 7 d after birth, a PDA can alter pulmonary mechanics (6-8). In addition, preterm infants with a PDA have increased ventilatory needs compared with infants whose PDA has been closed (6, 7, 9-12). Whether these alterations are due to increasing pulmonary edema or to more permanent histopathologic changes is currently unknown. Chronic pulmonary histopathologic changes consisting of alveolar simplification, fibrosis, and chronic inflammation frequently follow preterm birth (13). These changes, known as bronchopulmonary dysplasia (BPD), appear to be due to inflammatory and repair processes that interfere with normal lung development (14-17). Airway aspirates from infants that develop BPD contain proinflammatory cytokines (e.g., interleukin [IL] 6 and IL-8) during the first days after delivery (18), and ventilation of preterm animals initiates a similar inflammatory response (13,18). Although numerous studies have found an association between the presence of a PDA and development of BPD, there is little information suggesting a cause-and-effect relationship (19,20). Infants with a persistent PDA frequently require prolonged ventilatory support similar to infants with a more severe form of BPD; however, previous studies have failed to demonstrate consistent worsening in the radiographic features of BPD among infants with a persistent PDA (11,12,21). Studies to unravel the mechanisms responsible for the late pulmonary deterioration associated with a persistent PDA have been hampered by both the absence of randomized controlled clinical trials that address this question and by the absence of an appropriate animal model.The premature baboon (delivered at 125 d gestation; term ϭ 185 d) has a similar postnatal course as humans delivered between 25 and 27 wk of gestation. As in very-low-birthweight human infants, the ductus arteriosus of the premature baboon has only a 20 to 30% chance of closing spontaneously after birth (22). Despite surfactant treatment, low tidal volume breathing, and low supplemental oxygen administration, premature baboons develop pulmonary histopathologic changes during the first 2 wk after delivery that are similar to those described in premature human infants (13,23). The purpose of the present study was to examine the effectiveness of surgical ligation as a means of treating infants with a PDA by assessing its effects on cardiopulmonary function and the development of lung injury in mechanically ventilated premature baboons during the first 2 wk after delivery. We hypot...