Calcium Channel Blockers

Question 1

How does calcium work in the blood vessels?

Answer 1

action potential travels down smooth muscle, calcium channels open, contraction is initiated.

Question 2

What happens when calcium channels are blocked in the vessels?

Answer 2

smooth muscle contractions wont occur, vasodilation will result

Question 3

What do calcium channels regulate in the heart?

Answer 3

the SA node, the Myocardium, and the AV node

Question 4

How do calcium channels regulate the SA node?

Answer 4

calcium channels open= spontaneous firing

calcium channels closed/blocked= pacemaker activity declined (reduced HR)

Question 5

How do calcium channels regulate the myocardium?

Answer 5

calcium channels open= positive inotropic effect and increase contractile strength
calcium channels closed= contractile force diminished

Question 6

How do calcium channels regulate the AV node?

Answer 6

Calcium channels open= cells of AV node discharge more readily
Calcium channels close= discharge of AV nodal cells depresses, also decrease velocity of conduction through the AV node

Question 7

Dihyrdopyridines. Where do they act and what are they used for?

Answer 7

Act of the vascular smooth muscle ( blood vessels and arterioles).
Hypertension
Angina pectoris

Question 8

Non-dihyrdopyridines. Where do they act and what are they used for?

Answer 8

Vascular smooth muscle and heart.
HTN
Angina Pectoris
A-fib

Question 9

What are the side effects for all calcium channel blocker? .

Answer 9

• “my shoes don’t fit anymore” dose dependent peripheral edema
• headache
• flushing
• dizziness

Question 10

You know your patient is taking a calcium channel blocker. When they start experiencing severe reflex tachycardia, which drug and class would you expect as the cause? Why?

Answer 10

Nifedipine IR
reflex tachycardia more common with the Dihydropyridines and most intense for immediate release formulas in comparison to the SR forms.

Question 11

What is a way to suppress reflex tachycardia when taking dihydropyridines?

Answer 11

Add a beta blocker

Question 12

Non-dihydropyridine side effects?

Answer 12

Bradycardia
CYP34A interactions
Constipation (think verapamil)

Question 13

What should you avoid with Non-dihydropyridines (diltiazem and verapamil )?

Answer 13

Avoid giving to patients with heart failure or blocks

non-D’s have cardio-suppressant effects which can lead to bradycardia, partial or complete AV block, and exacerbation of HF

Question 14

Dihydropyrindes?

Answer 14

• Nifedipine XL
• Amlodipine
• Amlodipine/benazepril

Question 15

Non-Dihydropyrindes?

Answer 15

• Verapamil

* Diltiazem

Question 16

How exactly does Nifedipine IR cause reflexive tachycardia?

Answer 16

While this dihydropyrinde works on the calcium channels in the arteries (decreasing BP), it can have indirect effects on the heart by triggering the natural sympathetic response of the heart due to the decreased BP. This immediate release drug lacks cardiosuppresant qualities so cardiac action is unopposed.

Question 17

what is known as the pacemaker of the heart and allows the atria to contract at the same time?

Answer 17

SA node

Question 18

In a healthy heart, what is the function of the AV node?

Answer 18

The AV node will delay the signal from the SA node which provides time for blood to fill the ventricles before ventricular contractions.

Question 19

What is the function of the His-Purkinje System?

Answer 19

Conduct synchronized electrical excitation very rapidly through all parts of the ventricles