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

2020
Views:

483

Pages:

1
Author:

Alma Stephenson

4.4 – “Calc “Calcii-YUM quartet”: Clas Classs IV antiarrhythm antiarrhythmics ics • Non-dihydropyridine calcium channel blockers include diltiazem & verapamil (non-dairy Calci-YUM ice cream; Delicious Dark Chocolate & Very Vanilla) • Block activated & inactivated L-type calcium channels (L-shaped ice cream spigots) • Use-dependent (d/t blockage of activated & inactivated channels, rather than resting). More active in rapidly firing tissues & those that are activated more by calcium current – i.e. SA & AV nodes (nodal notes on heart-shaped music stand). • Effects of blocking are similar to effects of β-blockers. Recall AP upstroke is Ca2+ phase 0; K+ is phase 3 repolarization (note the upstroke of the keys). Most dramatic effect is at the AV node → slowed conduction (slowed conduction through the heart lamp). Particularly useful for treating supraventricular arrhythmias (top of heart light is lit). • Prolonged PR interval d/t slowed conduction from atrial P wave to ventricular QRS (PR guy). • When used in large doses or previous AV nodal disease, can cause heart block (hat shielding heart) • BY increase AV node refractory period, can slow ventricular response. Useful in rate control in A fib (rate controlling metronome; a-fib television).