Pharmacology of Heart Failure

Question 1

All patients must take _____ and _____

Patients with oedema must take ______

Answer 1

ACEi

Beta-blocker

Diuretic

Question 2

ACEi are 1^st line therapy.

Discuss the mode of action.

Answer 2

ACEi

e.g. ramipril, enalapril

Reduces aldosterone + vasoconstriction

Reduce salt + water retention

Inhibits RAS prevents remodelling

• Start on a low dose then upwards titration*
• Monitor urea/creatinine + K+ + BP before + during treatment*
• Cause first dose hypotension*
• Cause severe hypotension (withdraw diuretic)*
• Cause deterioration of renal function in pre-existing renal disease*
• Avoid renovascular disease*
• Cough*

Question 3

Describe the mode of action of AT₁ receptor antagonist

Answer 3

e.g. losartan

Angiotensin II acts at AT₁ receptors

AT₁ receptor antagonists block the action of AII

Less likely to rise to a cough

Alternative to ACEi

Question 4

Describe the mechanism of action and role of beta-blockers (e.g. bisoprolol) in the management of stable chronic heart failure.

Answer 4

1st line with ACEi

Beta1 selective

e.g. metoprolol, bisoprolol (alpha blocker/ antioxidant)

Know to reduce disease progression, symptoms + mortality

Reduce sympathetic stimulation, heart rate + O2 consumption

Antiarrhythmic = control rate in atrial fibrillation

Oppose neurohormonal activation leading to myocyte dysfunction

Ischaemia

Start with low dose

Question 5

Describe the role of loop and thiazide diuretics in the management of chronic heart failure.

Answer 5

Loop e.g. furosemide

• reduce circulating volune
• reduces preload on the heart
• relieve pulmonary + peripheral oedema

Thiazides or loop can cause hypokalaemia

Question 6

Describe the mechanism of action and role of an aldosterone receptor antagonist in the management of chronic heart failure.

Answer 6

e.g. Spironolactone

Mineralocorticoid (aldosterone) receptor antagonist

Now being used as an effective agent which reverse LVH

Question 7

Describe the mechanism of action and role of digoxin in the management of chronic heart failure and with concurrent atrial fibrillation.

Answer 7

+ive inotrope (increases contractility) due to loading up heart cells with calcium which forces contraction

impairs AV conduction + increases vagal activity

Heart block + bradycardia is beneficial in heart failure w/ atrial fibrillation (slowing heart rate improves cardiac filling)

Titrate dose to vetricular rate > 60 bpm

During repolarisation, calcium ions accumulate so sodium needs to be pumped in.

Question 8

What are the new treatments in CHF?

Answer 8

Ivabradine = inhibits If current

• HR > 75 bpm
• used with ACEi + BB

Sacubitril Valsartan = neprilysin inhibitor

• endopeptidase inhibitor
• enz breaks down natruretic peptides

Question 9

An add on therapy is vasodilators. What are they?

Answer 9

e.g. Nitrates, Hydralazine

Cause venodilatation

Reduce preload