VIII. Anesthetic considerations in CHD
Congenital Heart Disease - 6
A. General principles
- Fundamentally the same whether for cardiac or noncardiac surgery. Anesthetic implications follow logically
from knowledge of the altered physiology.
- Proper management of the physiologic abnormalities is more important than the choice of specific anesthestic
and pharmacologic approaches.
- Almost any anesthetic technic may be used in any CHD patient if the anesthesiologist understands the pathophysiology
of the lesion and the pharmacology of the drugs employed.
- Choice depends on
- Anesthesiologist's experience and skill
- Age and general condition of the patient
- Duration of surgery
- Presence of an IV
- Plan for postop ventilation
- precordial stethoscope
- pulse oximeter
- ECG(II +/- V5)
- BP cuff
- esophageal stethoscope
- two or more temperature probes
- +/- CVP line
- Pre-closure +/-:
- RA, LA and/or PA lines
- PA thermistor
- pacing wires
- See general principles.
- Younger, sicker patients
- Older, healthier patients
- thiopental, propofol
- inhalational agent (sevoflurane, halothane)
- Shunt lesions have interesting implications regarding speed of induction
- R-L shunt
- Inhalational - slower than normal
- Intravenous - faster than normal
- L->R shunt
- Inhalational - maybe faster than normal
- Intravenous - slower than normal
- Probably not clinically important
- Ketamine 1-2 mg/kg IM (or 4-8 mg/kg PO) may facilitate IV placement.
- AVOID AIR IN LINES
- Have vasopressors and vasodilators at hand. Perhaps initiate phenylephrine drip "background"
in infants with asymmetric septal hypertrophy (ASH, old IHSS).
- Appears NOT to elevate PVR if airway and ventilation are good.
- Relatively contraindicated in
- anomalous left coronary artery
- critical aortic stenosis
- hypoplastic left heart syndrome
- most commonly used in pediatric cardiac anesthesia
- infants have prolonged clearance, longer t1/2 for fentanyl
E. PDA ligation in the premature
- Perhaps best to avoid N2O
- some myocardial depression with fentanyl
- expansion of air bubbles
- AVOID AIR IN LINES
- air/O2/fentanyl +/- low-level inhalational agent
- neonates: narcotic technic usually first choice
- inhalational technic and early postop extubation considered for
- small VSD
- simple PS
- simple coarct
- PDA in older child
F. Cardiopulmonary bypass (CPB) - differences from adult
- Performed in NICU to avoid dangers of longer range transport
- Classic technic
fentanyl (20 mcg/kg)
- Newer alternative
pancuronium (or rocuronium) +
0.5 - 1 mg/kg induction then 50 mcg/kg/min
more complete agent (analgesia plus amnesia)
Note: right lateral decubitus near side of table, chest roll, grounding pad, IV and monitor lines
- Palliative shunts need to be occluded at onset of CPB.
- After good heparinization and hemodilution (Hct=25), profound hypothermia (T=15-20 degrees C) allows
1 hour of circulatory arrest.
- 15% of patients require inotropic support for weaning from CPB.
- Risk of respiratory failure greatest:
- age less than 6 months
- pulmonary disease
- large shunts
- Patient usually in 1 of 3 categories:
- Early extubation: simple, short procedures, e.g., ASD repair
- Shunt procedure: beware: large shunts may lead to pulmonary edema
- Complex repairs require postop ventilation; PEEP helpful except after Fontan procedure.