Cardiac Drugs

Question 0

Blood pressure

Answer 0

MAP = 2(DBP) + SBP / 3

MAP = HR x SV x SVR

Question 1

Phases of contraction

Answer 1

Phase 0: rapid depolarization, influx of Na through “fast” channels
Phase 1: beginning of depolarization, Na channels close, K and Cl open
Phase 2: Plateau, balance btwn Ca influx and K efflux
Phase 3: Ca channels close, cellular repolarization
Phase 4: Resting state returns Na influx, K efflux

Question 2

Chronotropic and Inotropic

Answer 2

Chronotropic: changes HR, affects nerves controlling heart, postive increases HR, negative decreases HR

Inotropic: Affects force of contraction, can be - or +

Question 3

Hypotension Drugs (Shock)

Answer 3

Fluids are first-line therapy

Catecholamines
NE, Isoproterenol, dopamine, phenylephrine, vasopressin
Inotropes
Dobutamine, Phosphodiesterase inhibitors cardiac glycosides

Question 4

Catecholamines

Answer 4

NE (Levophed) and EPI (Adrenalin)
endogenous catecholamines secreted by adrenal medulla
Net response is tachycardia and vasoconstriction

Isoproterenol 
  Synthetic catecholamine
  Treats symptomatic bradycardia or torsades de pointes 
  B receptor agonist 
  Limited use because of HR effects

Dopamine
Precursor to NE, Stimulates B receptors increases after load and myocardial oxygen demand

Phenylephrine
Purely a-agonist, vasoconstriction elevates total peripheral resistance

Vasopressin
Increases BP and water retention effect, aka anti diuretic hormone

Question 5

Inotropic agents

Answer 5

Dobutamine (dobutrex)
Short term treatment of heart failure
R-isomer causes positive Inotropic effects, vasodilation

Phosphodiesterase inhibitors (Inamrinone and milrinone)
  Inotropic vasodilator, increases cAMP

Cardiac glycosides (digoxin)
Management of CHF
Inotropic effect, inhibits Na/K ATPase pump
Narrow therapeutic margin

Question 6

Advanced cardiac life support pharmacotherapy

Answer 6

Epinephrine
1mg dose of 10 mL solution
Stimulates a-receptors and B Adrenergic effects
Decrease affinity in metabolic acidosis

Sodium bicarbonate
Dose 1mEq/kg
Limited use, will increase CO 2 levels
Used to keep pH above 7.2

Vasopressin
1 x dose of 40 units (substitute of dose of epinephrine)
Affinity not compromised in metabolic acidosis

Atropine
1mg IV push in asystole or PEA along with EPI or Vasopressin
Blocks acetylcholine

Magnesium sulfate
Used for torsades de pointes (caution in renal impairment)

Question 7

Alternative administration routes

Answer 7

Interosseous
for use in children especially and neonates
ETT
NAVEL…Naloxone, Atropine, Vassopressin, EPI, Lidocaine
Double the dose with dilute in 10 mL of NS or water, follow with vent.

Question 8

Hypertensive drugs

Answer 8

First line agents
  Angiotensin-converting enzyme inhibitors 
  Angiotensin II receptor blockers
  Calcium channel blockers 
  B-blockers
  Thiazide diuretics 

Second line
  Vasodilators 
  a-blockers
  a2 agonists 
  anti-adrenergics

Question 9

Angiotensin-converting enzyme inhibitors

Answer 9

Indications
Hypertension, heart failure, systolic dysfunction, MI prevention, LV dysfunction, and diabetic neuropathy

Common side effect is dry cough (treated with cromolyn sodium)

Significant interaction with NSAIDS

Mode of action 
  Block conversion of angiotensin I to II
  Reduce peripheral arterial resistance 
  Increase CO
  Increase renal blood flow

Question 10

Angiotensin II receptor blockers

Answer 10

Slightly weaker than ACEI’s

Indicated for hypertension and heart failure

Question 11

Calcium channel blockers

Answer 11

Indirect dilation of vasculature by blocking vasoconstriction via calcium channel blockade

Coronary and peripheral dilation
Verapamil and diltiazem (negative chronotropic/inotropic effects)

Question 12

B-blockers

Answer 12

Mode of action
Blockade of B receptors on renal juxtaglomerular cells, myocardial, and CNS receptors

May induce bronchospasm and render B-agonist ineffective