Calcium Channel Blockers Flashcards
Voltage-gated calcium channelsare activated by?
Membrane depolarisation
Voltage-gated calcium channels function
Allow selective diffusion of calcium ions in response to changes in cellular membrane potential down their gradient
L-type calcium channels are present where?
Vascular smooth muscle and ventricular myocytes etc
For cardiovascular disease, we look at what type of calcium channels?
L-type
L-type calcium channels are responsible for what? In skeletal, smooth and cardiac muscle
Excitation-contraction
Calcium channel blockers function
Decrease phase o up-slope
Therefore prolonging the overall cycle
Therefore slowing down the heart rate
Calcium channel blocker classes
Dihydropyridines
Non-dihydropyridines
Examples of Dihydropyridines
Amlodipine and felodipine
Examples of non-Dihydropyridines
Phenylalkylamine- verapamil
Benzothiazepine - dilitiazem
Non- Dihydropyridines aren’t vascular selective. Why?
Mainly work on the heart
Also reduce activity in vascular SMCs
Dihydropyridines are selective for vascular SMCs , therefore?
Have for lower effects on cardiac conduction
Clinical uses of calcium channel blockers
Hypertension
Angina
Vascular spasm
Arrhythmia
Role of calcium channel blockers in hypertension
Joint first line treatment for hypertension: usually amlodipine
CCB may not be sufficient and may require additional treatments
Other first line option treatments for CCB in hypertension are?
ACE inhibitors or angiotensin receptor blockers
Role of calcium channel blockers in angina: reduce pain?
By: reducing metabolic requirements of myocardium or improving blood supply
CCB in joint first-line treatment for angina usually? And other options?
Usually amlodipine
Other= beta-blockers
Angina describe
Chest pain arising from myocardial ischaemia
Underlying coronary artery disease (spasm) leading to inadequate Blood supply for myocardial metabolic requirements
Role of CCB in vascular spasm
CCB as vasodilators → often first-line
Example of vascular spasm
Explain what it is
Rynaud syndrome
= construction of digital arteries often by vasospams
= affected areas initially turn White (lack of blood) then blue (lack of oxygenated blood)
When good flow restored, Digits are red
In raynaud syndrome affected areas initially turn?
= affected areas initially turn White (lack of blood) then blue (lack of oxygenated blood)
=) associated with “pins and needles” and pain due to lack of oxygenated blood
Treatment for vascular spasms
Avoid precipitants (especially cold)
CCB as vasodilators
Role of CCB in arrhythmias
Which class of CCB? And mechanism
Non-dihydropyridine CCB: decrease calcium influx at phase 0
At SAN and AV node
→ therefore slows down the cycle and reduced heart rate
If you decrease phase o slope in cardiac cycle, what effect does this have?
Prolonged overall cycle → slowing down the HR
Clinical term for irregular or abnormal heart’ rhythm?
Arrhythmia
