Heart drugs Flashcards
How do Beta-blockers decrease HR?
Decrease If and Ica
How do Calcium-channel blockers decrease HR?
Decrease Ica
How does Ivabradine decrease HR?
Decrease If
Do beta-blockers decrease contractility? If so, how?
Yes- decrease cAMP. This decreases Ca sensitaization of Troponin C by PKA, decreases DHPR Ca channel open and decreases Ca ATPase (on SR) activity
Do calcium- channel blockers decreases contractility?
Yes- all types do
Does ivabradine decrease contractility? If so, how?
No- on decreases If so only affects SAN conduction, so only affects HR not contractility
Whats the difference between phenylakylamines and benzothiazepines, and dihydropyridines?
Phenylakylamines and benzothiazipines are rate slowing (alos affect contractility) CCBs and dihydropyridines are non-rate slowing CCBs (just affect SM contractility)
What is veramapil and what does it do?
A phenylakylamine CCB- decreases HR
What is dialtiazem and what does it do?
A benzothiazepine CCB- decreases HR
What is amlodipine and what does it do?
A dyhyrdropyridine CCB- decreases contractility of vascular SM
What effect can dihydropryridines have on HR?
They cause potent vasodilation which can cause reflex tachycardia via decreased firing of baroreceptors.
What would you use a organic nitrate for and how does it work?
To dilate the coronary vessels (increase myocardial oxygen supply) by increasing cGMP via guanyl cyclase activation
What would you use a potassium channel opener for and why does it work?
To dilate the coronary vessels (increase myocardial oxygen supply) by increasing potassium efflux, polarization of the SM cell, impairs ability to contract.
Give two side effects of verapamil?
Brdycardia, constipation
Give 3 side effects of dihydropyridines?
Ankle odema, headache/flushing and palpitations (reflex tachycardia)
What is the RMP of ventricular mycoyte?
-65mV
In the Vaughan Williams classification, what is class 1?
Sodium channel blockers (usually open to cause fast depolarisation)
In the Vaughan Williams classification, what is class 2?
Beta blockers
In the Vaughan Williams classification, what is class 3?
Membrane stabilisation/ blaockade of K channels (which cause slow repolorisation)
In the Vaughan Williams classification, what is class 4?
CCBs- they usually cause maintain depolarisation as well as enhance contractility.
Name 4 anti-arrythmic drugs
Adenosine, verapamil, amiodarone and digoxin
What is adenosine used to treat and how does it work?
Arrythmia- Binds to Gs on VSM, causing relaxation and binds to Gi on SAN, decreasing HR.
What is verapamil used to treat and how does it work?
Arrythmia- its a phenylakylamine CCB (so rate slowing). Used specifically to decrease ventricualr responsiveness to atrial arrythmias. Verapamil protects your Ventricular rate.
What is amiodarone used to treat and how does it work? Name 3 side effects
Arrythmia- spraventricualr and ventriular tachycardias because it prevents re-entry. manily by K channel bloackade, which prolongs repolarisation. Photosensitove skin rashes, thyroid conditions and pulmonary fibrosis.
