Management of CHF

Question 1

MOA furosemide

Answer 1

Loop diuretic - blockage of NaCl channels in the LOH, therefore decreasing corticomedullary gradient and decreased H2O reabsorption

Question 2

What side effects are associated with furosemide?

Answer 2

Pre-renal azotaemia and hypokalaemia (need to add potassium sparing diuretic)

Question 3

How can furosemide resistance occur?

Answer 3

GIT oedema causes malabsorption of drugs, tubular cell hypertrophy (caused by aldosterone) may leads to Na+ retention despite furosemide action

Question 4

Name a loop diuretic with greater potency than furosemide.

Answer 4

Torasemide

Question 5

Name an aldosterone antagonist diuretic.

Answer 5

Spironolactone/ amilozide

Question 6

How do we deal with pleural effusions?

Answer 6

Thoracocentesis in severe cases, medical diuretics if mild

Question 7

Name an ACE inhibitor.

Answer 7

Benazepril, enalapril

Question 8

True or false. ACE inhibitors are always administered as pro-drugs

Answer 8

True - they are activated in the liver

Question 9

How are ACE inhibitors eliminated from the body?

Answer 9

From the liver during renal impairment

Question 10

In which situation are ACE inhibitors contra-indicated?

Answer 10

Severely hypotensive animals where renal function is impaired - ACE inhibitors may further affect renal function and electrolyte levels.
Where there is a outflow obstruction?

Question 11

What side effects are associated with ACE inhibitors?

Answer 11

Hypotension, renal impairment, hyperkalaemia, anorexia, diarrhoea, vomiting

Question 12

MOA Telmisartan

Answer 12

Angiotensin II receptor blocker

Question 13

Name a venodilator which is used to rapidly control pulmonary oedema.

Answer 13

Nitroglycerine (GTN/ percutol)

Question 14

How do nitro-vasodilators work?

Answer 14

Produces NO which causes activation of GTP via guanylate cyclase to lower intracellular Ca2+ leading to vasodilation

Question 15

What benefits can arteriodilators have in CHF?

Answer 15

They reduce systemic blood pressure and therefore workload of the heart and reducing valvular regurgitation

Question 16

Name an artertiodilator.

Answer 16

Pimobenden (balanced), amlodipine, hydralazine, ACE inhibitors

Question 17

MOA Pimobendan

Answer 17

Ca2+ sensitizer and PDE inhibitor

Question 18

Why does pimobendan have less side effects than other PDE inhibitors?

Answer 18

No increase in Ca2+

Question 19

True or false. Pimobendan absorption is affected by the presence of food in the GIT.

Answer 19

True - give one hour before feeding

Question 20

Why are beta blockers contra-indicated in uncontrolled CHF?

Answer 20

Decreases sympathetic drive and therefore CO

Question 21

MOA Digoxin

Answer 21

Enhances vagal tone, reduced sympathetic drive - direct stimulation of vagal centres in the CNS, sensitisation of baroreceptors, enhanced pacemaker response to ACh

Question 22

How does digoxin work to reduce atrial fibrilation?

Answer 22

Slows rate of discharge of the SAN

Question 23

Outline the signalling pathway of digoxin which causes positive inotropy

Answer 23

Blockers of Na/K atpase causes increased intracellular Na+, which decreases activity of Na/Ca channels, increased Ca2+ leads to increased cellular contractility

Question 24

What side effects are associated with digoxin?

Answer 24

Excessive borborygmi, depression, anorexia, v+, d+, cardiac arrhythmias

Question 25

Outline the optimal quadrupal therapy for CHF

Answer 25

Furosemide, ACE-inhibitor (benazepril), Pimobenden, Spironolactone