The patient with Williams syndrome may present a significant anesthesia challenge. Several organ systems are affected by Williams syndrome; most important to the anesthetist are the effects on the cardiovascular and renal systems as well as the effects produced on the patient’s airway.

Williams syndrome patients are particularly prone to cardiac and cardiovascular anomalies, such as SVAS, peripheral branch pulmonary stenosis, and hypertension. The most disconcerting is SVAS (see Medical Management above). Before receiving any anesthetic, general or regional, the patient with Williams syndrome should undergo a very thorough cardiac evaluation. The anesthetist should obtain previous 12-lead electrocardiograms, echocardiograms, chest x-rays, and/or cardiac catheterization reports for comparison. Any of these reports not completed within the 12 months before the surgery date should be updated.

The anesthetist must strive to maintain the patient’s normal or usual resting heart rate. Avoidance of bradycardia or tachycardia and significant reductions in the systemic vascular resistance (SVR) are most important, along with maintenance of normotension (as close to what is normal for the patient as possible). Because of the strong need to avoid these possible effects, general anesthesia is likely the most appropriate anesthetic choice. Regional anesthesia, specifically subarachnoid or epidural blockades, should be avoided because of the sympathectomy it produces, resulting in significant reductions in both SVR and systemic blood pressure. The cardiovascular system of the patient with Williams syndrome should be closely monitored. The anesthetist should consider using an arterial pressure catheter, central venous catheter, pulmonary artery catheter, and/or transesophageal echocardiography to be able to more fully evaluate the patient’s cardiovascular stability perioperatively. The extent of the invasive monitoring will depend on the severity of the patient’s cardiac dysfunction along with the nature of the proposed surgical intervention.

The patient with Williams syndrome is prone to micrognathia as well as loose and/or brittle teeth—a state of generalized poor dentition that is not reflective of his or her hygienic routine or dental care. The patient’s airway should be assessed preoperatively. An underdeveloped mandible may indicate possible difficulty in securing the patient’s airway. Before obtaining consent for anesthesia, the anesthetist must fully advise the patient and/or parent or legal guardian (if the patient is a minor or mentally/intellectually incompetent) of the increased risk for dental trauma despite the anesthetist’s care, skill, and/or experience during the necessary direct laryngoscopy. It is absolutely necessary that the anesthetist have the difficult airway cart immediately at hand before induction of anesthesia.

The patient with Williams syndrome frequently has some degree of intellectual deficit or mental retardation. The level of the patient’s intellectual and emotional development must be strongly considered when deciding on premedication for anxiolysis. The anesthetist must also take into account the degree of cardiac dysfunction in the “equation” to determine the method, as well as magnitude, of premedication the patient should receive, if any. It may be most appropriate to have the parent or legal guardian accompany the patient until induction of general anesthesia is accomplished.

The patient’s kidney function should be assessed preoperatively. Hypercalcemia and hypercalciuria may predispose the patient to renal calculus formation, along with urinary tract disorders. The patient’s serum creatinine and blood urea nitrogen (BUN) levels should be obtained preoperatively for use as indicators of renal function.

The patient with Williams syndrome is predisposed to joint contractures, so the anesthetist must be acutely aware of these special needs when positioning the patient during surgery and anesthesia. Extra caution is necessary during the positioning process to ensure copious padding of extremities, bony prominences, and pressure points. Gelatin pads are preferable because they disperse pressure more effectively than do foam pads. The presence of any contractures may require considerable “creativity” on the anesthetist’s part to fulfill these needs.