A 78-year-old man with advanced renal disease has the ECG(lead II). What is the diagnosis?

(a) Source: (Fuster, p. 313)No atrial activity is detected. The ventricular rate is slightly irregular. Beat number 4 is a ventricular premature contraction. The T waves are tall and markedly peaked. This type of T wave is characteristic of hyperkalemia, as is absence of visible atrial activity. The potassium level was 8.2 mmol/L.