Heart Failure Pharmacology Flashcards
What are the principles of treating heart failure? (4)
Reduce Preload
Reduce Afterload
Increase Contractility
Restrict Cardiac Work
How does reducing preload help treat cardiac failure?
Increase stroke volume
by improving the position on the contractility curve (more initial stretching of myofibrils)
Also reduces pulmonary capillary hydrostatic pressure
- Reduce pulmonary oedema
How does reducing afterload help treat cardiac failure?
Increase stroke volume
by increasing the amount ejected during systole
How does increasing contractility help treat cardiac failure?
more contraction = higher stroke volume
What is increasing contractility at the expense of?
Cardiac work
What are the drug classes used in heart failure?(4)
Vasodilators
Diuretics
Postive inotropes
Cardio-inhibitors
What are some examples of vasodilators used in heart failure?
ACEIs / ARBs / nitrates / PDEIs
What is a PDEI?
A phosphodiesterase inhibitor
a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE)
preventing the inactivation of the intracellular second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) by the respective PDE subtype(s).
What are some examples of diuretics used in heart failure?
Loop / thiazides / MRAs (spironolactone, potassium sparing diuretics)
What is an MRA?
mineralocorticoid receptor antagonist
aldosterone antagonist
increase sodium excretion
reduces extracellular fluid volume
What is the mechanism of a thiazide diuretic?
inhibit sodium reabsorption in the DCT
What is the mechanism of a loop diuretic?
sodium-potassium-chloride cotransporter in the thick ascending limb
NKCC in Loop of Henle
increase water loss and sodium loss
reduce extracellular fluid volume
What are some examples of positive inotropes used in heart failure?
beta agonists / PDEIs / digoxin / levosimenden
Used acutely and closely monitored
What are some examples of cardio-inhibitors used in heart failure?
beta blockers
What is the difference between beta-agonists and beta-blockers
Overall, the effect of β-agonists is cardiac stimulation (increased heart rate, contractility, conduction velocity, relaxation) and systemic vasodilation.
Increase contractility.
β-blockers prevent binding of adrenaline and noradrenaline, inhibiting normal sympathetic effects
Management of confirmed heart failure with reduced ejection fraction (systolic)
Ensure drugs which may cause or worsen heart failure are reviewed and stopped if appropriate
Loop diuretic - reduce symptoms of fluid overload
- titrate dose and adjust as new medications added
Prescribe both an ACE Inhibitor and a Beta-Blocker
- only start one at a a time
- —-ACE first in diabetics or signs of fluid overload
- —-NOT ACE in person with clinical suspicion of haemodynamically significant valve disease
- —- if unable to tolerate ACE, give ARB
- ——-Beat blocker first if person has angina
If BB + ACE doesn’t work, refer to cardiology
consider anti-platelet in people with atherosclerotic arterial disease
consider statin if indicated
ensure comobidites and causes are managed
screen for depression/anxiety
supervised exercise group
assess nutrition status
influenza and pneumococcal vaccine
Management of heart failure with preserved ejection fraction (diastolic)
Ensure drugs which may cause or worsen heart failure are reviewed and stopped if appropriate.
Prescribe a loop diuretic - up to 80 mg furosemide (or equivalent), if necessary, to relieve symptoms of fluid overload.
Refer the person to a specialist for further advice on management.
consider anti platelets and statins
ensure comorbidities and causes are treated
screen for depression and anxiety
supervised exercise group and nutritional advice
influenza (annual) and pneumococcal (once) vaccines
Side effects of ACE inhibitors
Dry Cough Angioedema - above both from kinin build up - Hypotension Renal compromise - hyperkalaemia, impaired autoregulation
Side effects of ARBs
Symptomatic hypotension
Hyperkalaemia
Delayed onset angioedema
Doesn’t suppress aldosterone, no kind side effects
Side effects of loop diuretics
Hyponatraemia
Hypokalaemia
Deafness
Renal toxicity (with dehydration)
Limited effectiveness alone
Side effects of MRAs
Hyperkalaemia
Gynaecomastia (competes with testosterone at receptor)
Limited effectiveness alone
MRAs and Loop Diuretics have limited effectiveness alone, how is this combatted?
given together
spironolactone with furosemide
Side effects of Beta-agonists
Tremor
Headaches
Tachycardia
Not effective in Chronic heart failure
- only used in acute heart failure with reduced ejection fraction
Side effects of PDEIs
Hypotension - vasodilation
Reflex tachycardia
Arrhythmias
Worsens survival in chronic heart failure
Mechanism of cardiac glycosides (digoxin)
ion exchange in the cardiac myocyte
inhibit sodium/potassium pump
secondary inhibition of sodium/calcium exchange
rise in intracellular calcium - positive ionotropicity
slows AV conduction
Side effects of cardiac glycosides (digoxin)
Arrhythmias
Contraindicated
- hypokalaemia (alters toxicity level of digoxin)
- renal impairment
- AV block
Side effects and Unwanted effects of beta-blockers
Worsens contractility acutely
Bronchospasm in asthmatics
Cold hands and feet
Fatigue
Tachycardia Increased cardiac work Arterioconstriction Venoconstriction Renin release - sympathetic nervous system -
Which beta-blockers have specific advantages?
Bisoprolol - highly selective to beta-1 receiptors - main BB
Carvedilol - also has mild alpha-1 receptor blocking action
Nebivolol - highly selective for b1 receptors, enhances vasodilatation mediated by nitric oxide
