Drugs for Heart Failure Flashcards
define cardiac failure
the inability ‘of the heart to meet the body’s oxygen demands (can be chronic or acute)
what is forward failure?
the inability to pump blood out of the heart
is forward failure systolic or diastolic?
systolic
what are the symptoms of forward heart failure? (3)
- easily tired
- peripheral cyanosis (under perfusion of skin- goes purple)
- salt and water retention (under perfusion of the kidney)
what is backward failure?
inability to fill the heart
is backward failure systolic or diastolic?
diastolic
what are the symptoms of backward failure? (give 3)
- pulmonary hypertension
- reduced lung compliance
- breathlessness
- engorgement of liver
- oedema of legs and ankles
What are the 5 primary treatment strategies for cardiac failure?
- rest
- ACE inhibitor
- Beta-blocker
- diet
- diuretics
what do ACE inhibitors do for cardiac failure?
reduce cardiac preload and afterload
what do beta-blockers do for cardiac failure?
reduce sympathetic activation, slowing heart rate and allowing better ventricular filling
give 3 exaples of beta blockers used for cardiac failure
Carvedilol, Metoprolol and Bisoprolol
what are the 4 secondary treatments for cardiac failure?
- Positive inotropic agent
- aldosterone antagonists
- ATII receptor blocker (ARB)
- Isosorbide dinitrate/ Hydralazine
Give the main example of a positive inotropic agent
Digoxin
what does digoxin do?
increases force of contraction
as well as treating cardiac failure, what else can digoxin treat?
atrial fibrillation
What do aldosterone agonists do?
block activation of the renin-angiotensin- aldosterone system (RAAS)
what do AT11 receptor blockers (ARBs) do?
blocks RAAS
what’s different about the side effects of ACE inhibitors and ARBs?
ARBs don’t cause a cough as a side effect
where is Digoxin obtained from?
Digitalis lanata
What does Digoxin contain?
- Aglycone (determines its pharmacodynamic properties)
- lactone (gives it intermediate solubility)
- a steroid nucleus (lipid soluble)
- sugar residues (water soluble, determines pharmacokinetic properties)
How does digoxin molecularly affect the heart?
Inhibits Na/K ATPase, increasing the conentration of Na+ and inhibiting Ca2+ efflux
also increases sarcoplasmic reticular Ca2+- more calcium
How does digoxin physiologically affect the heart?
more calcium= more muscle contraction at a greater force
How does Digoxin affect cardiac rate/rhythm at pharmatherapeutic doses?
increases vagus activity, slowing SA node firing and slowing AVN conduction velocity. Overall ventricular contraction rate decreases
How does Digoxin affect cardiac rate/rhythm at toxic doeses?
increases sympathetic tone which can cause Arrhythmias by inhibiting nA/k atpASE. This increases after depolarisation causing ectopic beats
