Cardiac Flashcards
1
Q
Adrenoreceptors
A
- Bind catecolamines
- B1 (cardiac)- positively inotropic and chronotropic agonism increases O2 consumption. Antagonism does the opposite (also increases pre-load)
- B2 (respiratory)- agonism causes bronchodilation, alveolar clearance and decreases inflammatory cytokines
2
Q
Beta-blockers
A
- Cardioselective beta-blockers (bisoprolol) by antagonsim of B1 receptors in cardiac tissue reduce HR and BP which reduces myocardial oxygen demand
- NB- Non-selective BB such as carvediolol (B1 + B2 + A1 antagonism) also cause vasodilation
3
Q
Dihydropyridine CCBs
A
- Amlodipine/nifedipine
- inhibits transmembrane influx of Ca (no action potential) of vascular smooth muscle hence causes vasodilation of arteries/arterioles
4
Q
Non-dihydropyridines
A
- Diltiazem and verapamil
- More cardioselective- reduces inotropic effective of myocardium, reducing O2 demand
5
Q
ACEI
A
- Ihibit conversion of angiotensin I to angiotensin II (powerful vasoconstrictor)
- Angiotensinogen metabolised into AG I by renin, AG I -> AGII by ACE
- AGII as well as vasocontriction also causes aldosterone release, reabsorption of salt and water and ADH release
6
Q
ARB
A
Block AG II receptors
7
Q
Diuretics
A
- Loop: Inhibit the reabsorption of Na+/ K+/2Cl- in the ascending loop of Henlé
- Thiazide: Inhibit the active absorption of Na+/ and the passive absorption of 2Cl- in the distal tubule.
- K+ sparing- spiro is aldosterone antagonist increase Na+ excretion whilst limiting K +
- Amiloride also K+ sparing
8
Q
Cardiac glycosides
A
- Inhibit Na/K/ATPase pump, more excitable hence increase Ca2+ influx leads to strong contractility (positive inotropy)
- Also increases stimulation of vagus nerve (Negative chronotropy)
9
Q
Nitrates
A
- NO donator- increase NO leads to increased cGMP which alters phosphorylation of various membrane proteins causes vasodilation
- Reduces pre-load and afterload
