CV Calcium Channnel Blockers

Question 1

What are the indications for Calcium Channel Blockers?

Answer 1

1. Amlodipine/nifedipine used as 1st/2nd line treatment for hypertension
2. All Ca Blockers used to control stable angina
3. Diltiazem/Verapamil used to control cardiac rate in super ventricular arrhythmias, inc ST, A flutter, A fib.

Question 2

Mechanism of Action?

Answer 2

1. Decrease Ca entry into vascular and cardiac cells
2. Causes relaxation and vasodilation in arterial smooth muscle
3. Reduce Cardiac contractility
4. Suppress cardiac conduction
5. Reduce cardiac rate, contractility, afterload
   6 Hence reduces myocardial oxygen demand

Question 3

What are the two classes of Ca Blockers?

Answer 3

1. Dihydropyridines: amlodipine/nifedipine - selective for vasculature
2. Non dihydropyridines; verapamil/diltiazem - more cardioselective

Question 4

Important adverse affects?

Answer 4

1. Amlodipine/Nifedipine: ankle swelling, flushing, headache and palpitations
2. Verapamil: constipation, brady, heart block, cardiac failure
3. Diltiazem: a mixture of the above

Question 5

Warnings?

Answer 5

1. Verapamil/Diltiazem used in caution in patients with poor left ventricular function
2. Avoid in people with AV nodal conduction delay; provoke complete heart block
3. Amlodipine/Nifedipine avoided in patients with unstable angina: vasodilation causes a reflex increase in contractility and tachy
4. A/N avoided in patients with severe aortic stenosis

Question 6

Important interactions?

Answer 6

1. Verapamil/Diltiazem should not be Px with B Blockers

2. May cause HF, brady and asystole