heart failure Flashcards
cardiac output
stroke volume x hr
preload
force that stretches cardiac muscle prior to contraction - volume filling heart from venous return
afterload
pressure heart must exert to eject blood during ventricular contraction
how to reduce preload
furosemide diuretics
how to reduce afterload
increase diameter and increase contractility
vasodilators used in heart failure
ACEi, ARBs, nitrates, PDEIs (afterload)
diuretics in heart failure
furosemide (preload)
positive inotropes in heart failure
B agonists, PDEIs, digoxin
cardio-inhibitors in heart failure
b-blockers
ACEi MOA
- Prevents angiotensin i → angiotensin ii
- Increase in peripheral vascular resistance = increased afterload
side effects ACEi
dry cough and angioedema, hypotension, hypekalaemia
diuretics in HF
Loop diuretics act on aLOH to block NaKCC channels → increased sodium excretion and decreased ECF volume
side effects loop diuretics
hypokalaemia, deafness, renal toxicity
mineralocorticoid receptor antagonists in HF
Act in DCT to block aldosterone receptors - limited expression of sodium and potassium channels -> reduced preload
side effects mineralocorticoid antagonists
hyperkalameia and gynaecomastia
b agonists in HF
e. g. dobutamine
- B1 is cardiac specific and increases force of contraction
what would a1 do to heart
increase after load
side effects b agonists
tachycardia and no benefit in chronic disease
PDEIs in HF
- B1 adrenoreceptor
- Increase 2nd messengers intracellularly by preventing breakdown
side effects PDEIs
hypotension, tachycardia and arrythmias
what leads to increase heart contractility
b1 action
what leads to increased vasodilatation
b2 action
cardiac glycosides in HF MOA
- Ion exchange in myocytes
- Na/K pump inhibited
- Secondary inhibition of calcium/sodium exchange
- Rise in intracellular calcium = increased ionotropicity
- Lows AV conduction - used in AF
cardiac glycoside e.g.
digoxin