Potassium depletion in severe heart disease.

Exchangeable sodium and potassium, total body water, and sulphate space were measured in 42 patients with severe valvular heart disease who were free of oedema. Compared with normal subjects of the same height, no increase in exchangeable sodium was found but a mean potassium depletion of 27% was shown. This depletion was not related to diuretic therapy, and no relationship between the degree of depletion and postoperative arrhythmias was found. It is concluded that the major cause of the low exchangeable potassium is the reduction in cell mass that occurs in chronic heart disease, and that there is no significant fall in the intracellular potassium concentration.