Ch.22: Inotropes (Swift)

Question 1

inotropy =

Answer 1

contraction

Question 2

how do inotropic drugs increase contractility?

Answer 2

increase Ca available to increase interaction of actin/myosin

Question 3

cost of positive inotropes

Answer 3

• inc. myocardial O2 consumption
• myocardial ischemia
• maliganat arrhythmias

Question 4

4 classes of inotropes

Answer 4

1) cardiac glycosides
2) beta-adrenergic agonists
3) phosphodiesterase inhibitors
4) Ca sensitizing agents

Question 5

digoxin is what class of inotrope?

Answer 5

cardiac glycoside

Question 6

MOA of cardiac glycosides*

Answer 6

• inhib. Na/K ATPase pump –> inc. intracellular Na, which exchanges for Ca –> increased contractility
• DELAYS conduction of SA/AV nodes

Question 7

cardiac glycosides are used in patients with:***

Answer 7

• systolic myocardial (pump) failure (i.e. severe valvular dz, DCM)
• atrial fib

Question 8

digoxin is dosed based on**

Answer 8

LEAN body weight. Be careful when dosing in fat/edema dogs

Question 9

where is digozin excreted?**

Answer 9

kidneys. be careful when using in D/C with renal disease!!

Question 10

digoxin therapeutic window

Answer 10

narrow. Overdose results in cardiac toxicity (tachy/bradyarrhythmias), CNS signs (i.e. CTZ stim. –> vomiting), and GI signs (v/d/nausea)

Question 11

contraindications of digoxin use

Answer 11

• renal insufficiency, azotemia

- electrolyte disturbances, esp. hypokalemia, since K and digoxin compete for same binding sites**