Cardiac

Question 1

Digoxin

Answer 1

Positive inotrope - reversible inhibition og myocardial Na-K ATPase
- increase in intracellular Na, drives intracellular Ca

AV node inhibition - vagomimetic effects
Increased IC Ca –> prolongation of phase 4 and phase 0 of the cardiac action potention –> increases AV node refractory period

Adv effects:
Dysrhythmias - AV-block, multiforme VPCs
Cats very sensitive

Question 2

Pimobendan

Answer 2

Increases Ca sensitization to troponin C = increased contractility
PDE3 inhibitor = vasodilation (arterial and venous)

Adv effects: hyporexia, diarrhea, lethargy

Question 3

Diltiazem

Answer 3

Non-dihydropyridine Ca-channel blocker = class 4
- act primarily on nodal cells - prolong refractory period and slow conduction
- negative inotrope, negative chronotrope, coronary artery vasodilation

Adverse effects:
Bradycardia/ AV block, hypotension, anorexia

Question 4

Sotalol

Answer 4

B-blocker and K channel blocker (class III)
- prolongs repolarization, refractory period

Adv effects:
- negative inotrope, chronotrope
- dyspnea/ bronchospasm

Question 5

Lidocaine

Answer 5

Class IB - inhibits fast Na channel

Adv effects:
CNS: drowsiness, depression, ataxia, muscle tremors
Nausea and vomiting
Cats very sensitive to CNS effects, develop cardiac depression

Question 6

Mexiletine

Answer 6

Class 1B- fast Na channel blocker

Adv effects:
Vomiting and inappetence
Tremors/ ataxia - cats

Question 7

Procainamide

Answer 7

Class 1A - fast Na channel inhibitor
Supra and ventricular dysrhythmic

Adv effects:
Vomiting/ diarrhea
Hypotension, negative inotropism
AVB
Multiforme VT
Fever, leukopenia

Question 8

Furosemide

Answer 8

Loop diuretic - blocks Na-K-2Cl cotransporter
Renal venodialtion and transient increase in GFR

Adv effects:
Hypochloremia, hyponatremia, hypokalemia
Ototoxicity (high doses IV)

Question 9

Amiodarone

Answer 9

primarily fast rectifier K channel blocker. Class III; though exhibits properties of all classes

Adverse: vomiting, hepatopathy, thrombocytopenia
Other: Cordarone IV result in severe hypotension (polysorbate 80, benzyl alcohol - negative inotrope, hypotensive effects)

Question 11

Spironolactone

Answer 11

K sparing diuretic - aldosterone antagonist (distal renal tubules)
AE: hyperkalemia, dehydration