Heart Failure Flashcards
What causes sudden death in heart heart failure?
Arrhythmias
What are the main determinants of cardiac workload?
Preload
Afterload
Contractility
HR
What kinds of drugs decrease preload?
Venodilators
What kind of drugs reduce afterload?
Arteriodilators
What effect do B-blockers have on contractility
Decrease conractility
How do B blockers reduce cardiac work?
Slowing HR
When your heart is failing, what happens to preload
Increases due to increased blood volume and increased venous tone
What 2 classes of drugs will reduce preload in HF
Diuretic
Venodilators
What effect does HF have on afterload
Increased afterload due to increased aortic impedance and increased arterial constriction
What class of drugs will reduce afterload in HF
Arteriodilator
What effect does HF have on HR
HR is increased due to reflex tachycardia caused by sympathetic hyperactivity
How do B-blockers help in HF
They reduce energy expenditure by slowing the HR
Does not help in end stage HF
What is the MOA of digoxin?
Inhibits the Na+,K+ ATPase pump on the cell membrane. Leads to:
⬆️Intracellular Na+
⬇️Expulsion of intracellular Ca++
⬆️Intracellular Ca++ leads to increased Ca++ stores
⬆️Actin-myosin interaction by intracellular Ca++
⬆️Contractility (positive inotropy)
What is the #1 drug to increase inotropy
Digitalis
What effect does Digoxin have on normal healthy hearts
Decreases HR
Who can use Digoxin as an antiarrhythmic?
Patients NOT in heart failure!
How does Digoxin slow HR in normal hearts?
Vagal stimulation due to:
Sensitization of arterial baroreceptors
Stimulation of central vagal nuclei
Increased SA node sensitivity to ACh
How does Digoxin slow HR in FAILING hearts?
In HF, sympathetic tone will already be high, but Digitalis will reduce sympathetic tone by increasing myocardial contractility
Does Digitalis increase Cardiac output for everyone?
No, only in failing hearts.
Because peripheral vasoconstriction will increase in normal people