Magnesium sensitive, adenosine resistant, repetitive monomorphic ventricular tachycardia.
Repetitive monomorphic ventricular tachycardia (RMVT) is characterized by episodes of ventricular ectopy and nonsustained VT exacerbated by catecholamines. Because this arrhythmia is frequently adenosine sensitive, its mechanism is believed to be cyclic adenosine monophosphate-mediated triggered activity due to delayed afterdepolarizations. We present a case of RMVT associated with significant hypomagnesemia (serum level = 1.1 mg/dL), which did not respond to intravenous (IV) adenosine and terminated repeatedly after IV magnesium. Electrophysiologic study demonstrated an origin from the left sinus of Valsalva, which was successfully ablated. The combination of adenosine resistance and magnesium sensitivity may be consistent with an atypical RMVT mechanism related to inhibition of sodium-potassium adenosine triphosphatase (Na(+)-K(+) ATPase).
Neiger
Jeffrey S
JS
Department of Medicine, Section of Cardiology, Clinical Cardiac Electrophysiology Service, Rush University Medical Center, Chicago, Illinois, USA.
Gupta
Akshay
A
Halleran
Sean M
SM
Trohman
Richard G
RG
D000241:Adenosine / Q000494:pharmacology; D000328:Adult; D005260:Female; D006801:Humans; D008274:Magnesium / Q000097:blood / Q000627:therapeutic use; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000503:physiopathology*
D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D000241:Adenosine