CHF Drugs

Question 1

Enalapril

Answer 1

• inhibits angiotensin-converting enzyme (ACE), reducing conversion of angiotensin I to angiotensin II (potent vasoconsctrictor)
• results in decreased preload, increased ejection fraction, increased cardiac output, and hypotension (in volume depleted patients)

Question 2

Amlodipine

Answer 2

• blocks Ca2+ channels on vascular smooth muscle cells, resulting in decreased availability of Ca2+ to contractile apparatus
• results in vasorelaxation but has no effect on cardiac rhythm

Question 3

Indications to use amlodipine

Answer 3

• cats: reduction of systemic hypertension secondary to renal disease, cardiomyopathy, diabetes, hyperthyroidism
• dogs: hypertension and congestive heart failure

Question 4

Carvedilol

Answer 4

• blocks beta adrenergic receptors (beta1>beta2) and alpha1 adrenergic receptors, which decreases effects of chronic NE stimulation on failing heart
• results in long-term increased ejection fraction and decreased heart rate

Question 5

Dopamine and Dobutamine

Answer 5

• positive inotropic catecholamines that are agonists of beta1-adrenoceptors and/or dopamine receptors (dopamine only)
• result in increased cardiac output and supports blood pressure

Question 6

Indications to use dopamine and dobutamine

Answer 6

• acute heart failure

Question 7

Pimobendan

Answer 7

• inhibits phosphodiesterase III and V, leading to increased intracellular cAMP
• results in vasodilation, decreased preload, and decreased afterload

Question 8

Indications to use pimobendan

Answer 8

• used in dogs with congestive heart failure secondary to dilated cardiomyopathy or mitral valve disease

Question 9

Digoxin

Answer 9

• inhibits Na/KATPase, resulting in decreased Na+/Ca2+ exchange and higher intracellular [Ca2+]
• results in improved myocardial contractility

Question 10

Indications to use digoxin

Answer 10

• used for long-term management of late stage congestive heart failure