Cardio SketchyPharm Flashcards
What is one of the earliest lab values which indicates poor prognosis of digoxin toxicity?
Hyperkalemia -> elevated blood K+ levels due to too much blockade of Na/K ATPase
What does digoxin do to the ST segments with longterm use?
Concave ST segments - think of the taSTy scoop of ice cream
-> does not indicate toxicity, just longterm use
What are some common causes of digoxin toxicity?
- Hypokalemia - permissive effect on Na/K ATPase binding, usually loop diuretics or vomiting / diarrhea
- Renal insufficiency
- Drugs which inhibit tubular clearance of digoxin - i.e. verapamil, amiodarone, quinidine
What is the mechanism of action of milrinone?
You’re one in a million - Don’t phoster disinterest in the cAMPaign
Increases cAMP via being a PDE inhibitor. Causes:
- Vasodilation - think of the big red ears
- Increased contractility - increasing cAMP in a non-beta receptor dependent method - think of the poster flexing.
What is the mechanism of action of nesiritide?
Don’t BuMP the GruMP - It’s NECessary to turn the Tide
Increases cGMP via mimicking BNP
Decreases afterload and preload - think of the blue pants and red ears of the elephant
Also improves diuresis - think of stomping on those peanuts
What is the mechanism of action of ATII in the proximal tubule of the kidney?
Stimulates the Na/H exchanger, promoting contraction alkalosis
-> think of the guy watching the pro kart TV in sketchy
What lab value is expected to bump by about 30% after starting an ACE inhibitor?
Creatinine - think creatinine credit card
-> due to loss of AT2 constriction of the efferent arteriole and thus loss of GFR
Why do ACE inhibitors improve mortality in heart failure and post MI?
- They reduce AT2-mediated cardiac remodelling
- They reduce preload by reducing AT2’s affect at proximal tubule + aldosterone at distal tubule
- They reduce afterload by reducing AT2-mediated vasoconstriction
Why are ACE inhibitors contraindicated in pregnancy?
Increased risk of fetal hypotension, anuria, and renal failure
How does verapamil differ from diltiazem?
Note that verapamil (very vanilla) is farthest to the right in the sketch -> most cardioselective (non-DHP effect), and least smooth muscle effect (DHP)
Diltiazem is still quite cardioselective but acts a little more like the dihydropyridines in its L-type calcium channel blockade in smooth muscle (blood vessels)
What is the mechanism of amlodipine? Why is it preferred over other CCBs for the treatment of hypertension?
It is a dihydropyridine (all ‘dippins) calcium channel blocker which increases vasodilation via L-type calcium channel blockade in blood vessels
-> reduces afterload and stimulates coronary artery vasodilation
Preferred because it has a long halflife -> will not trigger reflex tachycardia as easily
When are nifedipine, nicardipine, and clevidipine used?
Nifedipine - a CCB known to be safe in pregnancy
Nicardipine - Nice card - rapid action and safe in hypertensive emergency
Clevidipine - Clover - rapid action and safe in hypertensive emergency
What CCB is contraindicated in patients with unstable angina or post-MI and why?
Nifedipine - think of the pregnant lady cutting through the heart-shaped apple
-> due to reflex tachycardia triggered by vasodilation, which increases myocardial oxygen consumption
Why do CCBs cause peripheral edema?
Arteriolar vasodilation increases the capillary hydrostatic filtering pressure -> more fluid into interstitium
What are the contraindications of CCBs in general?
- Concomitant use of beta blockers or another rate control agent -> additive heart blockade
- Heart failure - think of the guy with the heart failure balloon outside -> due to decreased cardiac inotropy (bad, that’s why we use digoxin), as well as reflex sympathetic activation
What is one classic side effect of verapamil other than constipation? What other drugs have this?
Gingival hypertrophy - think of the guy blowing gum
Also seen with phenytoin and cyclosporine (but not tacrolimus)
What are the first line treatments for primary (essential) hypertension and when should you consider using dual therapy?
Think of the black elderly guy in the pool holding ice cream for optimal treatment
- > HCTZ / CCBs i.e. amlodipine
- > casino is nearby - ACE inhibitors / ARBs also used
Considered using dual therapy if >20 mmHg over the target.
What are the values which indicate hypertensive emergency?
Think of the 180 degree arch over 12 inch ruler = 180/120
What are the beta blockers used in hypertensive emergency? Their mechanisms?
IV metoprolol or esmolol - selective beta1 blockade
IV labetalol - combined alpha1 and nonselective beta blockade
-> think of the pregnant labeta organist
What antihypertensive medications are safe in pregnancy?
Hydralazine, methyldopa (alpha-2 agonist), labetalol, nifedipine
What is the mechanism of action of most agents used in hypertensive emergency?
Arteriolar vasodilators -> direct drop in BP
What is the mechanism of hydralazine and when is its use contraindicated? Why can it cause fluid retention?
Direct arterial vasodilator which reduces afterload / BP. -> minimal effects on preload
Contraindicated in CAD / MI due to reflex tachycardia -> generally administered with a betablocker
Can cause fluid retention via sympathetic activation of RAA system in response
What is the usage of hydralazine in heart failure?
Can be used in combination with nitrates for a mortality benefit -> results in both preload / afterload reduction
Think of the mortality flag and the throwing of dynamite out of the hydralazine boat (nitrates).
What is the mechanism of action of sodium nitroprusside and its toxicity?
Metabolized to nitric oxide which increases the cGMP (grump) and leads to BOTH arterial and venous vasodilation
Toxicity - cyanide poisoning -> lactic acidosis and altered mental status
What is the signalling used by D1/D2 receptors?
D1 - Gs - increases cAMP
D2 - Gi - decreases cAMP
What is the mechanism of action of fenoldopam?
fenolDOPAm - D1 agonist. Much like beta2 receptors, it increases cAMP which causes vessel dilation.
It is particularly useful because D1 receptors are expressed on renal / splanchnic arteries -> permits vasodilation of these vascular beds in hypertensive emergency.