Williams Syndrome

The airway is not the problem - The dysmorphic facies (high prominent forehead, low flat nasal bridge, upturned nose, smooth philtrum, overhanging upper lip, widely spaced teeth) look striking, but the airway itself is rarely the difficulty in Williams syndrome. Do not let it absorb your preparation — the mortality here is cardiac, and the most dangerous minutes of the case are induction and the recovery period, not laryngoscopy.

Supravalvular aortic stenosis - SVAS narrows the aorta just above the coronary ostia and is progressive, worsening as the ascending aorta fails to grow. Review the ECG and the most recent catheterization and echocardiography reports, and speak to the patient's cardiologist about whether the imaging needs repeating before you anesthetize. On examination the systolic pressure in the right arm is typically higher than the left — cuff the right arm, or you will under-read the pressure you are trying to defend. Expect an absent ejection click.

Sudden cardiac arrest - This is the headline risk. Sudden cardiac death is reported at 25 to 100 times the age-matched rate, and in a registry of 447 patients undergoing cardiac surgery mortality was 5% with major cardiac events in 9%. The mechanism is oxygen supply-and-demand mismatch across obstructed outflow tracts with compromised coronary perfusion, ending in myocardial ischemia, falling cardiac output, and hemodynamic collapse. Anticipate and treat hypotension, bradycardia, and ST changes aggressively — do not observe them.

Why hypotension and tachycardia kill - With a fixed obstruction sitting above the coronary ostia, coronary filling depends on diastolic root pressure and on diastolic time. A fall in SVR drops perfusion pressure across a stenosis that cannot dilate to compensate, and tachycardia shortens diastole, so both halves of the supply equation fail at once while the hypertrophied ventricle ejecting against the obstruction is raising demand. Maintain preload and SVR, hold normal sinus rhythm at an age-appropriate rate, and avoid increases in PVR — with biventricular outflow obstruction the right ventricle is in the same bind as the left.

Fasting and hydration - Volume depletion is what converts a stenotic lesion into a collapsed circulation. Limit NPO time to 1 to 2 hours before the procedure with oral clear liquids or IV fluid, schedule the case first of the day, and for moderate and high Williams syndrome risk category patients consider admission the night before for IV access and hydration.

Induction technique - IV induction is preferred, particularly for moderate and high risk-category patients. Use a balanced anesthetic aimed at reducing myocardial oxygen consumption and minimize any reduction in SVR — know which of your agents drops SVR hardest and have the treatment drawn up before you give it. Consider pretreating with a vasoactive agent at induction.

Drug choices - Phenylephrine is first line and is preferred over epinephrine: you want SVR without the chronotropy and added demand. Continue beta blockers on the day of surgery. Premedicate for anxiolysis — the sympathetic surge that accompanies IV placement or a distressed emergence is itself a cardiac risk in this population.

Intraoperative monitoring - 5-lead ECG as a minimum so ST segments are actually visible. For moderate and high risk-category patients consider invasive blood pressure and TEE. QTc prolongation and hypertension are both described in Williams syndrome, so read the baseline ECG rather than assuming it is normal.

ECMO on standby - Recommended for moderate and high risk-category patients, and specifically for anyone with a history of arrest under anesthesia, SVAS presenting for a first catheterization, or concern for coronary artery stenosis. If standard resuscitation is not working, deploy early.

Hypercalcemia and renal disease - Infantile hypercalcemia with deranged vitamin D metabolism is part of the syndrome; hypercalcemia was documented in 13% of procedures in a recent 10-year single-center review. Check a preoperative serum calcium, and pick a calcium-free maintenance fluid. Renal dysfunction (22%), nephrocalcinosis (7%), and renal artery stenosis (4%) appeared in the same cohort, so check a creatinine alongside it.

Aspiration risk - GERD was documented in 39% of procedures in that cohort and failure to thrive in 41%. Plan for reflux, but weigh a rapid sequence induction deliberately — the hemodynamic cost of a fast, deep induction in a patient with biventricular outflow obstruction can exceed the aspiration risk you are trying to avoid. Make that a decision, not a default.

Developmental delay - Developmental delay was present in 87% of this cohort. Combined with the characteristically overfamiliar, highly verbal manner, patients can appear far more cooperative than they are. Bring the caregiver in and plan premedication rather than relying on rapport at the door.

The danger does not end at extubation - The single adverse event in a 10-year review of 46 procedures occurred about 60 minutes after anesthesia stop time: the child became agitated, developed ST-segment depression, then refractory VT/VF requiring venoarterial ECMO, and went to definitive SVAS repair three days later. Continue ECG and pulse oximetry monitoring afterwards, treat pain and shivering aggressively, and extend monitoring — 2 hours for low risk, at least 6 hours and preferably overnight with ICU considered for moderate and high risk.

Williams syndrome (Williams-Beuren syndrome) is a microdeletion at chromosome 7q11.23 that removes the elastin (ELN) gene, occurring in roughly 1 in 7,500 live births. Losing elastin produces a diffuse arteriopathy rather than one discrete lesion, and cardiovascular abnormalities are present in 80% to 90% of patients. The signature lesion is supravalvular aortic stenosis (SVAS) — narrowing of the aorta just above the level of the coronary arteries — which travels with branch pulmonary artery stenosis, aortic arch obstruction, coarctation of the aorta, and ostial stenosis of the carotid, renal, and iliac arteries. The lethal combination is biventricular outflow obstruction plus coronary ostial involvement: a hypertrophied ventricle working against a fixed obstruction cannot meet its own oxygen demand through a compromised coronary supply. Reported risk of sudden cardiac death is 25 to 100 times that of the age-matched general population.