Hyperkalemia-Induced T Wave Oversensing in an Implantable Cardioverter Defibrillator

Area of Science:

• Cardiology
• Nephrology
• Electrophysiology

Background:

• A 66-year-old female with end-stage renal disease and heart failure with reduced ejection fraction, status post implantable cardioverter defibrillator (ICD), presented with dizziness and fatigue.
• The patient's electrocardiogram revealed sinus rhythm, complete atrioventricular block, and a ventricular paced rhythm at 30 beats per minute (bpm).

Observation:

• Device interrogation showed a VVI mode with a lower rate limit of 40 bpm and T wave oversensing.
• Laboratory studies indicated significant hyperkalemia, with potassium levels at 7.9 mmol/dL.

Findings:

• Reprogramming the ICD to a higher pacing rate initially improved symptoms.
• Resolution of complete atrioventricular block and T wave oversensing occurred after successful correction of hyperkalemia.

Implications:

• This case underscores the critical importance of monitoring electrolyte levels in patients with implantable cardioverter defibrillators.
• Electrolyte disturbances, particularly hyperkalemia, can significantly impact cardiac device function and patient presentation.