Special Populations and Special Procedures: Congenital, Thoracic, Transplantation, and Electrophysiology
Congenital and thoracic
Congenital heart disease questions hinge on shunts and parallel circulations. A left-to-right shunt raises pulmonary blood flow; a right-to-left shunt causes cyanosis and risk of paradoxical embolism. In Eisenmenger syndrome, falling SVR increases right-to-left shunt; avoid systemic vasodilation and sudden decreases in preload. Single-ventricle patients are preload-dependent and may be sensitive to changes in pulmonary vascular resistance. For thoracic surgery, one-lung ventilation requires lung isolation, understanding of shunt physiology, and treatment of hypoxemia by recruiting the dependent lung, applying CPAP to the non-dependent lung, and checking tube position.
Transplantation and EP
Heart transplant recipients are denervated: the heart does not respond normally to atropine or vagal maneuvers and depends on circulating catecholamines and preload. Rejection and primary graft dysfunction are early concerns; pulmonary hypertension can precipitate right heart failure. Lung transplant patients are sensitive to fluid overload and rejection. In electrophysiology, ablation and device procedures require understanding of arrhythmia induction, anticoagulation, and lead extraction risks. Pacemaker and ICD patients need preoperative device interrogation and a plan for electromagnetic interference.
Traps
A common trap is giving a vasodilator to a cyanotic child with a right-to-left shunt, worsening hypoxemia. Another is assuming a transplanted heart will respond to atropine for bradycardia. In mediastinal mass cases, maintain spontaneous ventilation and avoid supine positioning until airway risk is assessed. Worked example: during one-lung ventilation, SpO2 falls; confirm tube position, increase FiO2, apply CPAP to the operative lung, and add PEEP to the dependent lung before escalating. Rule of thumb: in shunt physiology, ask which way the blood flows and what happens to PVR and SVR.