Figure 28. The effect of increases in serum K concentration on the ECG. At A the ECG is seen at a normal serum K level (5 meq./liter). At B there is a decrease in the resting transmembrane potential of the cardiac cells, a slowing of cardiac conduction (prolonged QRS complex) and an increase in the amplitude of the T wave. By the time the concentration has doubled (10 meq./liter) E there is a disappearance of the P wave and an even more marked slowing of conduction. These symptoms can be treated by the administration of intravenous Ca++ or the reduction of the serum K level.
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