Waterston shunt		A palliative operation for the purpose of increasing pulmonary blood flow, hence systemic oxygen saturation, which involves creating a small communication between the main pulmonary artery and the ascending aorta. Often complicated by the development of pulmonary vascular obstructive disease if too large. Not uncommonly caused distortion of the pulmonary artery. (Waterston DJ. Treatment of Fallot’s tetralogy in children under one year of age. Rozhl Chir 1962;41:181-183.)
Williams syndrome		An autosomal dominant syndrome, often arising de novo, associated with an abnormality of elastin, infantile hypercalcemia, mild cognitive impairment and the so-called “cocktail personality”, and congenital heart disease, especially supravalvar aortic stenosis and multiple peripheral pulmonary stenoses. (Williams JC et al. Supravalvular aortic stenosis. Circulation 1961;24:1311-1318.) (Beuren A et al. Supravalvular aortic stenosis in association with mental retardation and certain facial features. Circulation 1962;26:1235-1240.)
Wolff-Parkinson-White (WPW) syndrome		Accessory lateral atrioventricular conduction pathway causing characteristic ECG changes and atrial (and sometimes ventricular) arrhythmias. WPW syndrome may be isolated or associated with congenital heart defects. It is found in up to 25% of patients with Ebstein anomaly; typically, they have more than one accessory pathway.
Wood unit		A non-standard unit for expressing pulmonary vascular resistance (mmHg/L), named after Paul Wood, the famous British cardiologist. One Wood unit is equivalent to 80 dyn.cm.sec-5.