[Electrocardiographic changes in electrolyte imbalance. Part 1: Alterations in serum potassium (author's transl)].
163 patients (95 hypokalemic, 48 hyperkalemic, 20 healthy) were examined. Electrocardiographic patterns of hypokalemia were evident in 46 p.c. of all patients with serum potassium less than 3,5 mval/l. Patients without cardiac disease showed signs of hypokalemia in the ECG in 68 p.c., those cases with extremly low serum potassium (less than 2,5 mval/l) in 81 p.c. In patients without cardiac disease a good correlation could be observed between ST depression and T wave inversion on one side and serum potassium level below 3,5 mval/l on the other side. The T/U ratio was found to be below unity in only 9 p.c. in mild hypokalemia, but in 82 p.c. in severe hypokalemia. ECG pattern of hyperkalemia could be found in 29 p.c. of all patients with serum potassium levels greater than 5,1 mval/l. These signs were evident in patients without cardiac disease in 29 p.c. in mild hyperkalemia, but in 75 p.c. in severe hyperkalemia. Patients suffering from cardiac disease, however showed the correspondive ECG changes of hyperkalemia only in 5 p.c. There is a good correlation between the P, and T-wave-amplitude and the serum potassium level greater than 5,1 mval/l. According to our findings it can be stated, that the ECG changes in patients with cardiac disease tend to hide the correspondive changes of potassium disorder.