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  • Patients with repaired cardiac congenital disease are being seen more and more often for noncardiac surgery: important to understand lesions and repairs
  • Congenital heart defects have an incidence of between 4 and 50 per 1,000 live births
  • Most common: ventricular septal defect (VSD):
    • Most resolve spontaneously in the first few years of life
    • Larger ventricular defects (>5 mm) have a higher rate of spontaneous closure than smaller VSDs
  • Four most important physiologic pearls for congenital heart disease:
    • Know primary lesion shunt direction and lesion
      • Left-to-right shunt (noncyanotic):
        • Atrial septal defect (ASD)
        • VSD
        • Patent ductus arteriosus (PDA)
      • Right-to-left shunt (cyanotic): examples include tetralogy of Fallot, pulmonary atresia, tricuspid atresia, Ebstein anomaly
      • Complex shunt: truncus arteriosus, transposition of the great vessels, total anomalous pulmonary venous return, hypoplastic left heart syndrome
      • Obstructive lesions:
        • Aortic stenosis (AS)
        • Mitral stenosis (MS)
        • Pulmonic stenosis (PS)
        • Coarctation of the aorta
    • Know initial arterial oxygen saturation
    • Know pulmonary to systemic blood flow ratio (Qp/Qs)
    • Know the primary cardiac valve lesions (restrictive or regurgitant)
  • Knowing where the blood flows and in what proportion allows the provider to try to maintain a Qp/Qs ratio appropriate for the patient
  • Influencing pulmonary vascular resistance (PVR) is the most important way we have to optimize circulation in these patients
    • Carbon dioxide: hyperventilation and the resulting respiratory alkalosis decrease pulmonary resistance; hypoventilation and respiratory acidosis raise it
    • Nitrates: medications such as inhaled nitric oxide (5–40 ppm) or medications that affect the intracellular nitric oxide pathway (e.g., sildenafil) decrease PVR
    • Milrinone (an inotrope with vasodilatory effects) can decrease PVR and increase the ability of the right heart to contract
    • Inhaled or infused prostaglandins (inhaled: 5–50 μg/h; infused: start at 2 μg/h) selectively decrease PVR
  • A simplified template of normal blood flow is available below (Fig. 179-3)
  • Simpler procedures, such as ASD and some VSDs, are amenable to extubation in the OR. Other procedures, such as repair of PDA or repair of other lesions such as hypoplastic left heart syndrome or arterial switch procedures, involve complicated vessel and cardiac repair and are likely to require sedation and mechanical ventilation postoperatively

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Different Types of Cardiac Shunts Seen in Pediatric Patients
  • Left-to-right shunts
  • These shunts result from oxygenated blood being directed from the arterial circulation into the venous circulation without crossing a capillary bed resulting in a normal SpO2 reading, a higher than normal venous blood saturation, and a pulmonary blood flow (Qp) that is higher than the systemic blood flow (Qs). These shunts can occur anywhere from the atria to the precapillary blood vessels in end organs Faster inhalation induction
  • Right-to-left shunts
  • These shunts result from deoxygenated blood being directed from the venous circulation into the arterial circulation without crossing a capillary bed resulting in a low, abnormal SpO2 reading, a lower than normal venous blood saturation, and a pulmonary blood flow (Qp) that is lower than the systemic blood flow (Qs). These shunts can occur anywhere ...

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