Total body water, total exchangeable sodium and potassium in patients with convalescent acute myocardial infarction one to two months after onset.

Total exchangeable sodium (Nae), potassium (Ke), and total body water (TBW) were measured by the multiple isotope dilution method, in 10 healthy subjects (normal), 10 patients with congestive heart failure (CHF), and 47 patients with acute myocardial infarction (AMI), 1-2 months after onset. According to Killip's classification, 29 patients with AMI were classified as class I, and 18 patients were classified as class II and III (referred to as class II & III). No differences were found in plasma and urine sodium and potassium concentrations. By the multiple isotope dilution method, significant elevations in Nae/BSA (body surface area) were observed in the following order: normal, class I, class II & III and patients with CHF. Compared with normal subjects, Nae/BSA and Nae/Ke were elevated in class I patients. Elevations of Nae/Ke and TBW/BSA in both class II & III patients with AMI and patients with CHF indicated severe cardiac impairment. Both Nae/BSA (p = -0.60) and Ke/BSA (p = 0.71) had negative and positive correlations with the left ventricular ejection fractions (EF) measured by catheterization in 20 patients with AMI. This indicates a major sodium and water retention mechanism due to impaired cardiac function in AMI. It is worth noting that conspicuous abnormalities in body fluid compositions, particularly in class I patients with AMI as well as class II & III, remained despite no evidence of cardiac failure.