Author + information
- Joan Maradey, MD and
- Prashant Bhave, MD∗ ()
- Department of Cardiovascular Medicine, Wake Forest Baptist Medical Center, Winston-Salem, North Carolina
- ↵∗Address for correspondence:
Dr. Prashant Bhave, Department of Cardiovascular Medicine, Wake Forest Baptist Hospital, 1 Medical Center Boulevard, Winston-Salem, North Carolina 27157.
A 60-year-old man presented to the emergency department with 1 day’s history of fatigue. Electrocardiogram done on arrival showed a regular wide complex rhythm with a rate of 70 beats/min (Figure 1). Laboratory results showed hyperkalemia (serum potassium of 8.4 mmol/l, normal range 3.5 to 5.3 mmol/l). He underwent emergent hemodialysis with reduction in serum potassium to 5.1 mmol/l. Subsequent electrocardiogram demonstrated sinus rhythm at 75 beats/min with a narrow QRS complex and first-degree atrioventricular delay (Figure 2).
The presenting electrocardiogram demonstrates sinoventricular conduction, a rare finding particular to severe hyperkalemia (1). Animal studies have shown that hyperkalemia causes perturbations in atrial transmembrane potential that can result in marked delay in the activation of atrial musculature (2,3). As a result, sinoventricular conduction is characterized by conduction of impulses from the sinoatrial node to the atrioventricular node via specialized internodal pathways with the loss of discrete P waves (1). In Figure 1, the ventricular rate tracks with the atrial rate, but P waves are formed late and produce a short nonphysiological PR interval with intermittent loss of the P-wave within the wide and bizarre QRS complex (dashed arrows).
Dr. Bhave has received compensation for speaking at an educational program for Biotronik. Dr. Maradey has reported that he has no relationships relevant to the contents of this paper to disclose.
All authors attest they are in compliance with human studies committees and animal welfare regulations of the author’s institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Clinical Electrophysiology author instructions page.
- Received December 6, 2017.
- Accepted December 14, 2017.