The cardiovascular effects of ketamine used for induction of anaesthesia in patients with valvular heart disease.

The effects of induction of anaesthesia by ketamine 2 mg.kg-1 were studied in six patients with valvular heart disease before tracheal intubation and operation. Cardiac index was unaffected because a mean decrease in stroke index was compensated for a mean increase in heart rate. A significant increase was found in mean arterial pressure, pulmonary arterial mean pressure, pulmonary capillary wedge pressure and central venous pressure. Systemic vascular resistance increased, but not significantly, whereas pulmonary vascular resistance increased significantly by more than 150 per cent. Right ventricular minute work index increased in all patients, and the increase was as much as 400 per cent. Left ventricular minute work index increased in four of the six patients, but the magnitude of the increase was not so marked. It is therefore concluded that ketamine causes pronounced pulmonary vasoconstriction and an undesirable strain on the myocardium. Such effects could prove deleterious in patients with limited functional reserve of the right ventricle.