Inotropic Agents

Question 1

in CHF, how does the body try to compensate for the heart’s reduced pumping ability?

Answer 1

retain salt and water to incr the amount of blood in the bloodstream, increase HR, and increase size of heart

Question 2

what is the mechanism of action of inotropic agents?

Answer 2

act on heart by increasing the velocity and force of myocardial fiber shortening increase in contractility in increased cardiac output and blood pressure

Question 3

list examples of positive inotropic drugs

Answer 3

digoxin, dopamine, dobutamine, milrinone, norepinephrine

Question 4

list examples of negative inotropic drugs

Answer 4

flecainide and verapamil

Question 5

what do positive inotropic drugs do?

Answer 5

stabilize pts with HF as a bridge to heart replacement therapy

Question 6

what do negative inotropic drugs do?

Answer 6

keep heart muscles from working too hard and are used for HBP, chest pain, abnormal heart rhythm or hypertrophic cardiomyopathy

Question 7

which inotropic agents are cAMP dependent?

Answer 7

PDE inhibitors and glucagon

Question 8

which inotropic agents are cAMP independent?

Answer 8

digoxin
calcium
levosimendan

Question 9

what is the mechanism of digoxin on the heart?

Answer 9

inhibits Na/K-ATPase to increase intracellular Na concentration and cause accumulation of intracellular Ca to increase contractility

Question 10

what is the mechanism of digoxin on vascular smooth muscle?

Answer 10

inhibits Na/K-ATPase to cause depolarization due to increased calcium and smooth muscle contraction and vasoconstriction

Question 11

digoxin can cause toxicity, what are the SEs?

Answer 11

arrhythmias, delayed after depolarization tachycardia, AV block, sinus bradycardia, altered cognition, blurred vision, or nausea

Question 12

how do we treat digoxin toxicity?

Answer 12

atropine for AV block and sinus bradycardia
supply K to decrease affinity of Na/K-ATPase for digoxin
anti-digoxin immunotherapy

Question 13

what are pimobendan and levosimendan and what do they do?

Answer 13

calcium sensitizers: improve cardiac function without increasing cAMP and intracell calcium. causes the interaction between actin and myosin filaments to be prolonged to increase myocardial contractility

Question 14

which one is the most potent calcium sensitizer?

Answer 14

levosimendan

Question 15

explain what levosimendan specifically does?

Answer 15

-combines a positive inotropic action and a vasodilator property via ATP-dependent K channels
-stabilizes the interaction between Ca and troponin C
-opens the KATP channels of smooth muscle cells

Question 16

does levosimendan inhibit PDE?

Answer 16

no

Question 17

explain what pimobendan specifically does?

Answer 17

-positive inotropic effects lowers the Ca level required for actin sliding
-incr binding efficiency of cardiac troponin
-inhibits PDE3
-vasodilates by inhibiting PDE2
-inhibits production of cytokines

Question 18

which of the calcium sensitizers is considered a vet med?

Answer 18

pimobendan

Question 19

Inotropes adverse events: the increase in oxygen consumption can lead to increased risk for?

Answer 19

ischemic patients