What are the anesthetic considerations for patients with Williams syndrome undergoing surgery?

Williams Syndrome Anesthetic Considerations

Patients with Williams syndrome require meticulous anesthetic planning with cardiac anesthesia consultation, strict hemodynamic control, and avoidance of myocardial oxygen supply-demand mismatch, as they carry a 25-100 times higher risk of sudden death compared to the general population, with cardiac arrest occurring in approximately 2% of anesthetics. 1, 2

Risk Stratification and Preoperative Assessment

Williams syndrome patients require comprehensive cardiovascular evaluation before any anesthetic procedure:

• Obtain detailed echocardiography to assess for supravalvular aortic stenosis (present in up to 70% of patients), coronary artery stenosis, and other arteriopathy from elastin gene defects 1, 3
• Cardiac anesthesia consultation is mandatory for all procedures, even non-cardiac surgery, given the 11.1% cardiovascular complication rate and documented cardiac arrests 2, 4, 5
• ECG assessment for evidence of myocardial ischemia or ventricular hypertrophy from chronic pressure overload 3
• The mortality rate is approximately 0.9-3.4% for anesthetics in this population 4

Hemodynamic Management: The Critical Priority

Maintain mean arterial pressure within 10-20% of baseline throughout the entire perioperative period to prevent myocardial ischemia from coronary artery stenosis and ensure adequate coronary perfusion pressure across stenotic lesions 2, 5, 3:

• Avoid hypotension aggressively - even brief episodes can precipitate myocardial ischemia and cardiac arrest in patients with coronary artery anomalies 1, 3
• Avoid hypertension equally - sudden increases in afterload can worsen supravalvular aortic stenosis and precipitate left ventricular failure 5, 3
• Have vasopressors immediately available: phenylephrine (used in 35.1% of cases), norepinephrine (17.3%), calcium (22.8%), and dopamine (10.4%) 2

Anesthetic Agent Selection

Use propofol or etomidate for induction with sevoflurane or isoflurane for maintenance, as these agents provide hemodynamic stability when carefully titrated 2:

• Propofol was used safely in 37.6% of cases, etomidate in 26.2% 2
• Sevoflurane (68.3%) and isoflurane (47.5%) are acceptable volatile agents with careful blood pressure monitoring 2
• Avoid high concentrations of volatile anesthetics that cause excessive vasodilation and hypotension 5, 3

For muscle relaxation, use rocuronium or vecuronium - avoid succinylcholine due to risks in patients with connective tissue abnormalities 6, 3:

• Non-depolarizing agents provide controlled, titratable neuromuscular blockade 6
• Avoid atracurium and mivacurium due to histamine release that may trigger vasodilation and hypotension 7, 6

Intraoperative Monitoring

Invasive arterial blood pressure monitoring is strongly recommended for continuous beat-to-beat assessment, especially for procedures longer than minor interventions 5, 3:

• Continuous arterial line monitoring allows immediate detection and correction of blood pressure deviations 5
• Maintain SpO2 ≥95% continuously to prevent hypoxemia-related myocardial stress 6
• Consider central venous access for longer procedures or those with anticipated hemodynamic instability 5

Temperature and Positioning

Maintain strict normothermia throughout the procedure using forced-air warming devices and warmed intravenous fluids 6:

• Temperature extremes can trigger vasospasm and worsen coronary perfusion 6
• Pad all pressure points meticulously due to connective tissue fragility and risk of skin breakdown 6

Postoperative Management

All Williams syndrome patients require ICU or high-dependency unit admission for continuous cardiopulmonary monitoring for at least 24-48 hours, even after seemingly uncomplicated procedures 6, 2:

• The median length of stay after anesthesia was 2.8 days in one large series 2
• Continue SpO2 monitoring continuously for minimum 24 hours 6
• Do not discharge to regular ward - extended monitoring is mandatory as cardiovascular collapse can occur in the immediate postoperative period 6, 4

Critical Pitfalls to Avoid

• Never proceed without cardiac anesthesia consultation - this is not optional even for "minor" procedures 2, 5
• Never allow even brief hypotension - coronary perfusion is critically dependent on adequate diastolic pressure in stenotic vessels 1, 3
• Never use drugs causing histamine release (morphine, atracurium, mivacurium) that may precipitate vasodilation 7, 6
• Never assume low risk based on procedure type - 95.7% of non-cardiac procedures had no cardiovascular events, but the 4.3% that did included cardiac arrests 2

Special Considerations for Non-Cardiac Surgery

With appropriate planning and strict adherence to hemodynamic goals, risk can be substantially mitigated for non-cardiac procedures 2:

• 89.6% of anesthetics had no adverse events when managed with these protocols 2
• However, two cardiac arrests occurred (one requiring ECMO), emphasizing that risk cannot be eliminated entirely 2
• Resuscitation equipment including ECMO capability should be immediately available for high-risk patients 2, 4