Magnesium sensitive, adenosine resistant, repetitive monomorphic ventricular tachycardia

Area of Science:

• Cardiology
• Electrophysiology
• Biochemistry

Background:

• Repetitive monomorphic ventricular tachycardia (RMVT) is typically linked to triggered activity mediated by cyclic adenosine monophosphate.
• This mechanism is often sensitive to adenosine, a drug that targets this pathway.

Observation:

• A patient presented with RMVT refractory to intravenous adenosine.
• The arrhythmia episodes were repeatedly terminated by intravenous magnesium administration.
• Significant hypomagnesemia was noted in the patient (serum level = 1.1 mg/dL).

Findings:

• Electrophysiologic study identified the RMVT origin in the left sinus of Valsalva.
• Successful ablation of the arrhythmogenic focus was achieved.
• The adenosine resistance and magnesium sensitivity suggest an atypical RMVT mechanism.

Implications:

• This case highlights a potential alternative mechanism for RMVT, possibly involving sodium-potassium adenosine triphosphatase (Na(+)-K(+) ATPase) inhibition.
• It underscores the importance of considering electrolyte imbalances, such as hypomagnesemia, in refractory cardiac arrhythmias.
• Findings may guide future therapeutic strategies for atypical RMVT cases.