Chapter 48: Calcium Channel Blockers Flashcards
calcium channel blockers have the greatest impact on
heart and blood vessels
calcium channel blockers are used to treat
hypertension, angina pectoris, and cardiac dysrhythmias
calcium channel blockers are also known as
- calcium antagonists
- slow channel blockers
calcium channels open =
contractile process
calcium channels blocked =
vasodilation
consequences of therapeutic doses
selectively act on peripheral arterioles and arterioles of the heart (no significant effect in veins)
consequences of calcium channel blockers on the heart
- myocardium (-/+ inotropic effect)
- SA node (pacemarker, reduce heart rate)
- AV node (decrease conduction velocity)
calcium channel blockers act like
beta blockers
classifications of calcium channel blockers
- Dihydropyrides
- Phenylalanine
- Benzothiazepine
Dihydropyridines example
Nifedipine
Dihydropyridines act primarily on
arterioles
Phenylalanine example
Verapamil
Verapamil acts on
arterioles and directly on the heart and blood vessels
Benzothiazepine example
Diltiazem
Diltiazem act on
arterioles and directly on the hear and blood vessels
Verapamil and Diltiazem effects
Hemodynamic effects
what are the 5 Hemodynamic Effects
- Blockade at peripheral arterioles (reduces arterial pressure)
- blockade at arteries and arterioles of heart (increases coronary perfusion)
- blockade at SA node (reduces heart rate)
- blockade at AV node (decreases AV nodal conduction)
- Blockade in the myocardium (decreases force of contraction)
what is the most important hemodynamic effect
Blockade at AV node
Verapamil [Isoptin] therapeutic uses
- angina pectoris (vasospastic and exertional angina)
- essential hypertension (second line agent)
- Cardiac dysrhythmias (atrial flutter, atrial fibrillation, paroxysmal supraventricular tachycardia (IV)
- headaches
verapamil [Isoptin] is
highly protein bound
- 1st pass metabolism
verapamil [Isoptin] adverse effect s
- constipation **
- Dizziness
- facial flushing
- headache
- edema of ankles and feet
- Gingival hyperplasia
- heart block
Verapamil [Isoptin] food interaction
Grapefruit juice
Verapamil [Isoptin] toxcitiy
- severe hypertension
- bradycardia and AV block
- ventricular tachydysrhythmias
Diltiazem [Cardizem, Tiazac] benefits
- similar to verapamil except less constipation
Diltiazem [Cardizem, Tiazac] administration
oral preperations often sustained release formulas
Diltiazem [Cardizem, Tiazac] is used for
hypertension, angina, and cardiac dysrhythmias
Nifedipine cannot be used to treat
dysrhythmias
Nifedipine is less likely than verapamil to exacerbate
preexsiting cardiac disorders
Nifedipine [Adalat, Adalat XL] theapeutic uses
- angina pectoris
- hypertension
- investigational basis: relieve migraine headaches
Nifedipine [Adalat, Adalat XL] direct effects
- limited to blockade of Ca channels in vascular smooth muscle
Nifedipine [Adalat, Adalat XL] has no direct suppressant effect on
automaticity, AV conduction, or contractile forces
Nifedipine [Adalat, Adalat XL] indirect effects
lowered blood pressure (BP) activates baroreceptor reflex (primarily with immediate release versus sustained release)
Nifedipine effects
- lowered blood pressure
- increased heart rate
- increased contractile force
Nifedipine adverse effects
- flushing
- dizziness, headache
- peripheral edema
- gingival hyperplasia
- chronic eczematous rash (older patients)
- increases cardiac oxygen demand
Nifedipine can be combined with _____ for prevention of __________
beta blocker
reflex tachycardia
Nifedipine adverse effects
- increased mortaliy in patients with MI and unstable angina
Nursing implications for Nifedipine
- monitor BP, rhythm, HR
- many are sustained release (do not crush)
- monitor for constipation, peripheral edema, cardiosupression
