Serial Cardiac Output and Blood Volume Studies Following Cardiac Valve Replacement

The cardiac output and blood volume were measured preoperatively and sequentially during the early postoperative period in 45 patients undergoing cardiac valve replacement. Most patients showed a prompt, highly significant increase in cardiac output. Those with uncorrected valvular disease, even though apparently trivial, had lower cardiac outputs. The blood volume was sharply reduced from the preoperative level in almost every patient. When this was associated with low cardiac output, replacement of the blood volume deficit was usually accompanied by a prompt increase in cardiac output. Failure to respond in this way occurred only in patients with residual valvular lesions or myocardial disease.