Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content ++eFigure 32-1Graphic Jump LocationView Full Size||Download Slide (.ppt)Diagram of neonatal transitional circulation.++ Fetal circulation (parallel) in transition to complete adult circulation (series)Is essentially a complete adult circulation in series, but with PDA and patent foramen ovalePotential for shunting exists, determined by relation between SVR and PVRDeterminants of SVR Intrinsic autoregulatory mechanismsEnvironmental temperatureRadiant warmer–induced vasodilationDeterminants of PVR Alveolar hypoxiaReduced total pulmonary vascular bedSensitization of pulmonary vascular bed by sustained asphyxia ++ Prenatally, ductus arteriosus (DA) is a vascular connection between the main pulmonary artery (occasionally proximal LPA) and the aorta, diverting blood from pulmonary to systemic circulation.Postnatally, the vasa vasorum to the DA constrict, leading to necrosis of the medial muscular layer → ductal closure.In preterm infants, the DA wall thickness is proportionately less than in term infants, allowing passive diffusion of nutrients from the ductal lumen to the medial muscular layer, even after constriction of the vasa vasorum → higher rate of ductal patency.DA closed in 50% of full-term infants by 24 h, 90% by 48 h, >99% by 96 h.Incidence in term infants: ∼0.02%–0.04% (10% of all CHD in term infants). Incidence in preterm infants: ∼45% of infants <1750 g, ∼80% of infants <1000 g.Increased in: prematurity, hyaline membrane deficiency, asphyxia, high altitude, CHD, increased fluid administrationDecreased in: antenatal steroids, intrauterine growth restriction, prolonged rupture of membranesSpontaneous closure of PDA occurs in 38%–85% of babies <1500 g and in 25%–34% of those <1000 g. ++Table Graphic Jump Location|Download (.pdf)|PrintMedicalSurgicalComplicationsTransient or permanent renal impairmentThoracic duct trauma resulting in chylous effusionHeme-positive stools, ? association with necrotizing enterocolitis (NEC)Nerve damage resulting in vocal cord paralysisImpaired platelet functionSurgical site infectionThrombocytopeniaPostoperative hypotension and circulatory insufficiencyContraindicationsSerum creatinine >1.8 mg/dLUncontrolled bleeding diathesisPlatelet count <60,000Ductal-dependent cardiac diseaseBleeding diathesisNECDuct-dependent cardiac lesionsSepsis +++ Clinical Manifestations ++ Large PDA can be diagnosed relatively accurately based on clinical findings.Small PDA usually requires an echocardiogram with Doppler, because findings may be similar to pulmonary disease or sepsis.Clinical findings of moderate to large PDA:HypotensionMurmur (Continuous, “machinery”-like, may be intermittent)Heart failure (Poor feeding, apnea, respiratory failure)Wide pulse pressure (>25 mm Hg)Hyperdynamic precordiumBounding pulses (± Palmar pulses, prominent pedal pulses)Respiratory compromise (Increased ventilator support or inability to wean ventilatory support) +++ Diagnosis ++ CXR May be normal, or may see pulmonary edema or cardiomegaly (compare films serially)Echocardiography with Doppler Findings associated with hemodynamically significant PDA include: Ductal diameter >1.5 mmPredominantly left-to-right shuntDisturbed diastolic flow in MPAReversal of end-diastolic flow in postductal aortaLeft atrial/left ventricular enlargementElectrocardiography (no specific findings exist for PDA) May be normal, or may see LVH, BVH, or LAE ++... Your Access profile is currently affiliated with [InstitutionA] and is in the process of switching affiliations to [InstitutionB]. Please select how you would like to proceed. Keep the current affiliation with [InstitutionA] and continue with the Access profile sign in process Switch affiliation to [InstitutionB] and continue with the Access profile sign in process Get Free Access Through Your Institution Learn how to see if your library subscribes to McGraw Hill Medical products. Subscribe: Institutional or Individual Sign In Error: Incorrect UserName or Password Username Error: Please enter User Name Password Error: Please enter Password Sign in Forgot Password? Forgot Username? Download the Access App: iOS | Android Sign in via OpenAthens Sign in via Shibboleth You already have access! Please proceed to your institution's subscription. Create a free profile for additional features.