Excerpt

A 47-year-old man presented to our hospital with anasarca and anhelation. His medical history included prior myocardial infarction, chronic glomerular nephritis, chronic renal insufficiency, and no family history of sudden death. On admission, physical examination showed a blood pressure of 150/100 mmHg, a heart rate of 106 bpm, jugular venous distention, and anasarca. Initial laboratory data showed normal potassium levels (K⁺ 5.35 mmol/l, normal range 3.5–5.5), normal sodium levels (138 mmol/l, normal range 136–145 mmol/l), increased blood urea nitrogen (79 mg/dl, normal range 7–20), and increased creatinine levels (8.9 mg/dl, normal range 0.8–1.2). The primary electrocardiogram (ECG; Fig. 1 a) showed sinus tachycardia and prior anteroseptal myocardial infarction. A diagnosis of chronic glomerular nephritis, chronic renal insufficiency, acute left heart failure, and pneumonia was made. Furosemide and cefoperazone were administered intravenously for 2 weeks. The left heart failure and pneumonia were under control. The patient developed pericarditis, pericardial effusion, and anuria, which were unresponsive to diuretic therapy and required intermittent hemodialysis, but he declined it. The ECG tracing (Fig. 1 b) showed sinus rhythm (100 bpm), significantly dynamic changes compared with the admission ECG: The P wave amplitude was lower, the duration of the QRS complex was widened from 0.06 to 0.10 s, indicating intra-atrial and intraventricular block caused by high potassium. The laboratory data showed a high potassium level (K⁺ 7.09 mmol/l, normal range 3.5–5.5). Calcium gluconate was administered, and emergency hemodialysis was offered but the patient again declined. On hospital day 15, the patient’s serum potassium level reached 7.84 mmol/l and the ECG (Fig. 1 c) revealed the absence of P wave and wide QRS complex duration (0.18 s) indicating sinoventricular conduction and intraventricular conduction delay. The QRS morphology basically mimicked the last ECG and the RR interval was 0.58–0.64 s. Four hours later, the ECG (Fig. 1 d) transiently showed irregular rhythm with the widest QRS duration (0.22 s), alternation of short–long RR interval, and equivalent short plus long RR interval in each combination (three times the length of the RR interval), followed by 1.76 s (0.59 × 3), 1.79 s (0.60 × 3), and 1.77 s (0.59 × 3). These ECG characteristics revealed sinoventricular conduction with Wenckebach block (conduction ratio 3:2). Subsequently, the ventricular conduction velocity gradually slowed down until cardiac arrest. …