Heart Disease, Congenital

CHD is the most common birth defect.

Incidence: 1:25 live births.

85–90% of pts with CHD survive to adulthood in USA due to advances in medical care.

The highest risk factors of this complex disease include HLHS; poorly compensated physiology; presence of long-term complications (arrhythmia, pulm Htn, CHF); and emergency surgery.

Intermediate risk factors include major surgery, age less than 2 y, preop hospital stay >10 d, ASA physical status IV or V.

Cardiac failure.

Pulm Htn defined as PAP >25 mm Hg at rest and >30 mm Hg during exercise.

Arrhythmias.

Cyanosis.

Mortality: there is a twofold increase in mortality in children with congenital cardiac lesions compared to those without CHD who present for noncardiac surgery.

POCA registry.

Majority of cardiac arrests occurred in general OR (54%) in children undergoing noncardiac surgery.

Out of all the children with heart disease that arrested, 75% of them were <2 y, often with unrepaired lesions.

Resource availability: Is this child’s cardiac history too complex for this institution/periop team?

• Send the following children to a specialist center: Cyanosis, neonate with CHD, Eisenmenger syndrome, pulm Htn, aortic stenosis, HLHS, single ventricle physiology (BT shunt/Sano, Glenn, Fontan).

• If true emergency and cannot be transferred, then understanding anatomy, physiology, and shunting is key to management.

• Use PICU for postop management, especially complex lesions.

Maintain forward flow/cardiac output.

Balance pulmonary and systemic blood flow.

Maintain adequate tissue oxygen delivery.

Prevent arrhythmia.

Optimize fluid balance.

How to group these children: There are multiple ways, but the most useful is by physiology.

Normal “series” circulation: Most repaired pts; there can be a small amount of mixing.

• ASD/VSD

  • L-to-R shunting: This increases pulmonary blood flow and potentially decreases systemic blood flow.

  • R-to-L shunting: Deoxygenated blood flows into systemic circulation and causes reduced pulmonary blood flow and increased cyanosis.

  • Changes in SVR and PVR during anesthesia have the greatest effect in pts with large, unrestrictive defects.

Parallel “balanced” circulation:

• Pts with large AV septal defect or VSD, BT or Sano shunt, Truncus arteriosus.

• Mixing of systemic venous and pulmonary venous blood; potential for cyanosis.

• Balance between SVR and PVR.

Single-ventricle circulation:

• Blood flows passively to the lungs down a pressure gradient from the pulmonary artery to left atrium in pts who have a Glenn shunt or Fontan circulation.

• Changes in intrathoracic pressure or in PVR affect pulmonary blood flow, which then affects systemic blood flow.

• BT or Sano shunts are usually the first stage of creating Fontan circulation (palliative, to supply blood flow to the lungs).

  • Graft is connected between the subclavian artery (BT) or right ventricle (Sano) and the pulmonary artery.

  • Complete mixing of systemic venous and pulmonary venous blood (normal SpO ₂ 75–85%).

  • Flow is determined by SVR and PVR ratio: These pts are sensitive to changes in PVR or SVR, which can be caused by increased FIO ₂ , changes in PaCO ₂ , and volatile anesthetics or other vasodilators.

• Glenn shunt is second stage of Fontan repair:

  • Bidirectional superior cavopulmonary shunt.

  • Connects SVC to the right pulmonary artery.

  • IVC drains to right atrium.

  • Pulmonary venous and systemic venous blood mix, yielding SpO ₂ 75–85%; pt will have cyanosis after procedure.

  • Can tolerate FIO ₂ 100% usually without issues.

• Fontan circulation:

  • Inferior vena cava connected to the right pulmonary artery.

  • Separates the pulmonary and systemic circulation.

  • Passive flow to pulmonary circulation.

  • Normalizes oxygenation (children are sensitive to increases in PVR; decreases blood return to the heart, leading to a reduction in cardiac output).

  • Pressure gradient from the pulmonary artery to LA is the force driving pulmonary blood flow.

Genetics/syndromes:

• Chromosomal abnormalities: Down syndrome (up to 30% can have heart defect), trisomy 18 and 13, Turner syndrome, Cri-du-chat syndrome, Wolf-Hirschhorn syndrome, DiGeorge syndrome

• Associations: VACTERL

• Syndromes: William syndrome, Goldenhar syndrome, Marfan syndrome, Noonan syndrome, Smith-Lemli-Opitz syndrome

Family history of congenital cardiac disease

Maternal factors/medications:

• Untreated maternal PKU has a sixfold increased risk.

• Preexisting maternal diabetes has a fivefold increased risk.

• Medications: Lithium, thalidomide, isotretinoin, and bactrim.

• Rubella.

• Febrile infection, especially in the first trimester.