Sine-Wave Pattern Arrhythmia and Sudden Paralysis That Result From Severe Hyperkalemia
A 54-year-old man with a history of end-stage renal disease treated with hemodialysis presented to the emergency department because of a sudden inability to move his limbs.
Physical examination revealed a complete quadriplegia. Blood pressure was 145/90 mm Hg, with a regular pulse of 45 beats per minute. Initial 12-lead electrocardiography showed a sinus bradycardia with atrial, atrioventricular, and intraventricular conduction delay (Figure 1). Subsequently, the patient developed several episodes of a nonsustained wide-complex tachycardia with a right bundle-branch block configuration that gradually evolved into and from a “sine- wave” pattern (Figures 2 and 3⇓). Remarkably, the patient remained hemodynamically stable. Because hyperkalemia was suspected, serum potassium was determined in venous as well as arterial blood samples to be 9.9 mmol/L. Calcium gluconate was administered, and emergency hemodialysis was performed. After normalization of the serum potassium concentration, sinus rhythm was maintained, the cardiac conduction times returned to normal (Figure 4), and the quadriplegia resolved completely.
This case illustrates some typical features of severe hyperkalemia. Initial characteristic electrocardiographic abnormalities in hyperkalemia are tall and peaked T waves, followed by an increasing cardiac conduction delay. As demonstrated in this case, this results in flattened and broadened P waves, an atrioventricular block of first or higher degrees, and widening of the QRS complex. In rare instances, ST-segment elevation may occur, which leads to a “pseudoinfarction” pattern.1 Progression of hyperkalemia causes further widening of the QRS complex, often with the configuration of a left or right bundle-branch block. Eventually, merger of QRS complex and T wave will lead to the appearance of a typical sine-wave pattern. Contrary to our patient, a sine-wave pattern often precedes ventricular fibrillation or asystole.2 Furthermore, rapidly progressing flaccid motor weakness may result in a quadriplegia, which was the presenting symptom in this case and is an uncommon manifestation of severe hyperkalemia that may ultimately result in respiratory failure.2,3
Recognition of the combination of sudden paralysis and electrocardiographic abnormalities as demonstrated in this case can lead to early diagnosis and treatment of severe hyperkalemia.
Sims DB, Sperling LS. Images in cardiovascular medicine. ST-segment elevation resulting from hyperkalemia. Circulation. 2005; 111: e295–e296.
2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, Part 10.1. Life-threatening electrolyte abnormalities. Circulation. 2005; 112: IV121–IV125.
Freeman SJ, Fale AD. Muscular paralysis and ventilatory failure caused by hyperkalaemia. Br J Anaesth. 1993; 70: 226–227.