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41 Cards in this Set

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Inotropic effect
influences contractility or force of contraction
+ Inotropic effect
more force of contractility
- Inotropic effect
less force of contractility
Chronotropic effect
influences rate

+ : increase beats or faster rate
- : slower rate or less beats
Dromotropic effect
influences conduction through specialized conducting tissues (fibers)
Cardiac Glycosides
What is another word for Digitalis?
functional refractory period
A period when the heart cannot be stimulated to depolarize again.
force
Drugs may change the ______, rate, and rhythm of the heartbeat.
digitalis

Cardiac Glycosides
1. Class of chemicals with very similar chemical structures
a. all have sugar structural group
2. Some can be extracted from plants
a. Digoxin - (Lanoxin) - from white foxglove - builds toxic levels if renal failure
b. Digitoxin (Crystodigin) - from purple foxglove (Digitalis purpura)

WATER SOLUBLE
digitalis
Used chiefly for positive INOTROPIC action
But also affects rate (- chronotropic action)
And especially conduction (-dromotropic effect) in the heart.

What drug?
Used chiefly for positive INOTROPIC action
But also affects rate (- chronotropic action)
And especially conduction (-dromotropic effect) in the heart.
What are the actions that digitalis does to the heart?
+ inotropic action
- chronotropic
- dromotropic
What are the mechanisms of action for Digitalis (Cardiac Glycosides)?
1.increases Ca++ release within cardiac muscle (stronger)
2.increases Ca++ ion movement into muscle (with slow conduction)
3.increases parasympathetic (vagal) tone***
What are the mechanisms of Cardiac Glycosides?
release
Ca++
vagal
1.increases Ca++ _______ within cardiac muscle (stronger)
2.increases _____ ion movement into muscle (with slow conduction)
3.increases parasympathetic (______) tone***
Congestive heart failure

Atrial flutter, fibrillation, or paroxysmal tachycardia
What are the therapeutic uses for Cardiac Glycosides (digitalis)?
congestive heart failure
heart fails to pump adequate amount of blood

gigantic fluid overload + weak heart
Enlarged heart

Pulmonary edema

Systemic edema

Failng kidney

Increased heart rate
What are the symptoms of congestive heart failure?
hypertension
rheumatic fever
myocardial infarction
What are the causes of Congestive heart failure?
Supportive treatment of congestive heart failure w/digitalis
Decreased weight, increased physical activeity, and decreased Na intake, and treat hypertension if present.
heart size decreased to normal

lower HR

diuresis
When using Digitalis, What are the results (3) for congestive heart failure?
Atrial flutter
(therapeutic effect)

______ ______ (200-300 bpm) or fibrillation (more than 300 bpm) or paroxysmal tachycardia (irregular beats) - usually requires higher dose than treating CHF.
vagal
muscarinic
refractory
Atrial flutter (mechanism of action)

Increases ______ tone (a ________ effect) and directly depresses electrical conduction in atria and AV node. This protects ventricles from receiving too many stimuli and increases ________ period.
worst
narrow
Digitalis is frequently prescribed but has one of ______ margins of safety. _____ therapeutic index.
Visual

Ventricular arrythmias
What are the side effects of digitalis (cardiac glycosides)?
Visual side effect for digitalis
often single color vision (yellow or green tinged vision), white halos around objects, blurred or double vision.
Ventricular arrythmias (side effects)
If greatly decreases BP may cause dizziness or fainting.

Ventricular tachycardia
Ventricular fibrillations
AV block
Ventricular tachycardia
increased automaticity with more ectopic beats)

always dangerous and is found above moderate doses "bigeminy" - coupled beats indicates toxicity.
Ventricular fibrillations
most common cause of death in digitalis overdose

(ectopic beats set up competing refractory periods.)
AV block
ventricular rate decreases below 60 bpm and must take pulse regularly (due to - dromotropic effect - increased vagal tone slows impulses to ventricle.)
1. Recent myocardial infarction
2. Ventricular tachycardia
3. Partial heart block
4. Cardioversion (electroshock)
5. Calcium admission
6. Potassium depletion
7. Renal and hepatic disorders or older patient
What are the contraindications or cautions for digitalis (cardiac glycosides)?
1. Recent myocardial infarction
contraindication of digitalis

prone to developing arrythmias

digitalis may have additive or synergisticeffect and if failure present, will probably give anyway.
2. Ventricular tachycardia
contraindication of digitalis

may throw into fibrillation (increased ectopic foci and automaticity)
3. Partial heart block
contraindication of digitalis

may produce complete block

better choice is to implant artial pacing wires (may be done with local anesthetic)
4. Cardioversion (electroshock)
contraindication of digitalis

may cause fibrillation that will not respond to further shocks.
5. Calcium admission
contraindication of digitalis

Ca++ has synergistic effect with digitalis - toxic effect
6. Potassium depletion
contraindication of digitalis

e.g. due to some diuretics - increased toxicity

(need K+)
ACE inhibitors
B blockers
Aldosterone blockers
What are some (3) CHF alternatives?
ACE inhibitors
_____ _______ are now recommended first for cases of heart failure though digitalis and direutics are most often prescribed as well.
B blockers
___ ________ may decrease hospitalization and lower mortality.
first
digitalis
diuretics
ACE inhibitors are now recommended ______ for cases of heart failure though _________ and _________are most often prescribed as well.
Aldosterone blockers
produced peripherally in the heart and in major BV independent of adrenal aldosterone. Aldosterone directly induces collagen myopathy in heart muscle. Aldosterone stops reuptake of catecholagmines so it induces sympathetic arrythmias. Blocking both of these effects would be beneficial.