University:
University of North Carolina at Chapel Hill
Course:
NURS 312 | Pharmacology
Academic year:

2020
Views:

355

Pages:

1
Author:

Charlee Buchanan

4.5 – “DJ Fox Foxglove glove Discotheque Discotheque”: ”: Class V ant antiarrhythmics iarrhythmics (ba (basically sically everyt everything hing else) • Basically a catchall term for all other drugs useful in arrhythmias that don’t fall clearly into Classes I – IV. Alternative antiarrhythmics include digoxin, adenosine, potassium, magnesium • Digoxin (DJ foxglove) o positive inotropic effects. o Exerts parasympathomimetic effects via direct stimulation of vagus nerve (Vegas sign). Because cholinergic effects are much more powerful in the atria → inhibition AV node somewhat selectively. o AV nodal activity useful as rate control in A-fib & flutter (A-fib screens) • Magnesium (magnetized moonwalk) o Used to treat torsade des points (torn up rhythm strips) o Mechanism is unknown; known that Mg can affect various ion channels, including Na-channels, K+ channels, & Na-K-ATPase • Potassium o May be administered in management of arrhythmias, as both hyperkalemia & hypokalemia can both induce arrhythmias (Banana dancers). o Hyperkalemia: Will present with cardiac conduction abnormalities, ascending weakness, and paralysis as well. ECG will display peaked T-waves with shortened QT interval (streamer shape over dancer pointing upward). o Hypokalemia: will present with severe muscle weakness, renal abnormalities, glucose intolerance. May see U waves on ECG (streamer shape with gal pointing down). • Adenosine (“Swing dancing” with purine shaped gate) o Activates inhibitory A1 receptors on the myocardium & SA & AV node (A1 sign). effects: ▪ ↑K conduction & increased outward K+ current → hyperpolarization (banana flying through the air) ▪ suppressed inward Ca current → suppressed Ca2+ dependent action potential (ice cream on the floor). Calcium dependent action potential occurs in nodes, predominantly AV. Depression → ↓AV conduction & prolonged AV refractory period (nodal notes on dance floor). Results in decreased AV conduction (disconnected heart sign) o half-life is only 10 seconds o Indications ▪ Acute treatment of supraventricular arrhythmias (e.g. #1 first line treatment for PSVT conversion) (upper half of a heart with #1 ribbon) ▪ Also a vasodilator → ↑ coronary blood flow (red crown). Mediated by binding A2 receptors. o Major CV effects → major adverse effects. Note that extreme toxicity is rare d/t short half-life. ▪ Flushing (flushed dude) ▪ SOB (resting with exertion) ▪ Chest pain (clutching chest) ▪ Sense of impending doom (looks worried) ▪ Headache (gal with hand to head) ▪ Hypotension (gal fainting) ▪ May have high-grade AV block of extremely short duration (hat shielding heart) o Less effective in presence of methylxanthines (including caffeine & theophylline) which block adenosine receptors (kid antagonizing adenosine entrance while drinking an energy drink)