This ECG is from the same patient. It was recorded a few months later when her serum potassium was 8.2.mM. Note that the P wave and QRS complex are wider than on the earlier tracing, that the PR interval is now 0.20 seconds, that the frontal plane axis has shifted to the left and that the T waves are now symmetrical and peaked, giving them a tented appearance. These changes occur when the serum potassium level exceeds 7.0mM and become progressively more pronounced as the serum potassium concentration rises to even higher levels.