Figure 94-28b

Potassim and the electrocardiogram(ECG).after treatment and at a level of 3.6 meq/liter,the PR ,QRS,and T waves are normal. At 6.8 meq/liter, The PR and QRS are prolnged,with a shift of the QRS axis to the left ,and the T waves are symmetrical, narrow based,and tall--the so-called tented T waves. At a K level of 8.4 meq/liter there is further prolongation of PR ,the P wave becomes difficult to identify, the QRS axis shifts to the right, and theQRS prolongs to 0.20 s.T he characteristic prolongation of boththe initial and terminal portions of the QRS is best illustrated in V6.