Introduction to CV Pharmacology - Orlando Health

CV Pharmacology
Miscellaneous Antidysrhythmics
Adenosine (Adenocard)
Adenosine interrupts electrical conduction in the AV nodal reentry pathways making it effective
against supraventricular tachyarrhythmias and narrow complex tachyarrhythmias of unknown
origin. A rapid IV push bolus of adenosine causes complete depolarization of the myocardium,
resulting in a brief asystolic period that allows the heart's electrical activity to "reset" and return
to sinus rhythm. Because of this action, administration of adenosine is often referred to as a
"chemical cardioversion.”
Indications
Generally slow the rhythm down sufficiently to allow for correct interpretation of atrial
fibrillation or atrial flutter so that appropriate intervention may be made.
Precautions
Adenosine can induce a brief period of asystole, of 6-10 seconds. It is vital to have emergency
resuscitation equipment readily available.
Magnesium
Magnesium is essential for the functioning of the sodium-potassium pump to drive myocardial
electrical activity. A low serum magnesium level slows the return of potassium into the cell
during phase 4 of the action potential, resulting in a prolonged relative refractory period and QT
interval. Patients with a magnesium deficiency commonly have a high incidence of cardiac
dysrhythmias, including torsades de pointes (TdP) and sudden cardiac death.
Precautions
IV administration can cause hypotension and circulatory collapse if given too fast.
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