inotropic drugs in heart failure Flashcards
heart failure
heart is unable to pump enough blood to meet the body’s metabolic needs
(left or right ventricular HF)
inotropic drugs
drugs that increase the force of myocardial contraction
types of inotropic drugs
- cardiac glycosides (digoxin)
- sympathomimetic drugs
- phosphodiesterase inhibitors
other drugs used in HF
diuretics, b blockers, ACe inhibitors, ARBs, vasodilators, organic nitrates
causes of HF
cardiac muscle defect (MI, congenital)
SVD (afib, aflutter)
other (CAD, hypertension, DM, valve deficiency)
HF outcomes
structural changes in cardiac tissues (ventricle)
functional changes in ability of ventricle to pump blood
HY symptoms
- reflex tachycardia (response to decrease CO)
- edema
- elevated venous pressure
- dyspnea
- weakness
- enlarged heart
inotropic meaning
force of muscular contractions
- positive (digoxin)
- negative (b blocker)
chronotropic meaning
rate of heartbeat (SA node - origin of electrical activity)
dromotropic meaning
conduction speed of electrical impulses (AV node - spread of electrical activity from atria to ventricles)
digoxin
- cardiac glycoside
- positive inotropic drug
- from natural source (foxglove)
digoxin MOA
inhibit Na/K atpase in heat muscle (Na out and K in)
- binds to area where K binds to ATPase acting as competitive inhibitor
- more Ca can enter cell when there is more Na to move out with it
- more Na in the cell lets more Ca enter cell (heart beat more forcefully)
3 Ss of digoxin action
- positive inotropic effect (strengthen)
- negative chronotropic effect (slows - decrease HR at SA)
- negative dromotropic effect (slows - decrease AV node conduction)
digoxin effects
- increase SV (&CO)
- increase venous BP
- increase coronary circulation
- promote diuresis and improve kidney perfusion
- more o2 to body, easier to breathe, less fluid buildup
digoxin indications
- HF (relieve symptoms)
- SVD
given in 0.25, 0.125. 0.0625 mg/tab
