1 - Cardiac Glycosides Flashcards
What is the inability of the heart to provide the necessary output called?
Congestive Heart Failure
What complicates CHF?
- Insufficient bloodflow, reflex sympathetic output
- Increases heart rate, peripheral resistance, O2 demand
What’s the target drug therapy for congestive heart failure?
- Block sympathetic nervous system***
What are the symptoms of acute CHF?
- Tachycardia
- Shortness of breath
- Edema
- Decreased exercise tolerance
What are the symptoms of chronic CHF?
- Various arrhythmias
- Hypertension
- Cardiomegaly
- Edema
What are the symptoms of Right side heart failure vs Left side?
- Right Side
- Fatigue
- Dyspnea
- Edema
- Left Side
- Reduced cardiac output, blood pressure
- Pulmonary congestion
- More acute
What are the goals when treating CHF?
- Slow heart rate - increase filling time
- Increase contractile force to improve ejection fraction
- Increase cardiac output
- Reduce retention of salt and water
- Decrease sympathetic nervous system
What is the drug of choice for treatment of congestive heart failure?
- digoxin (Digitek, Lanoxin)
- from foxglove plant
What is the mechanism of action for digoxin?
- Inhibits Na/K ATPase pump
- Increases contraction of heart
- Postive inotropic effect
- Directly suppresses AV node conduction to increase ERP and decrease conduction velocity
- Slows heart rate - negative chronotropic effect
Why do glycosides cause diuresis?
- Decreases venous return
- Allows heart to become efficient
- Decreases filling pressure, heart rate and heart size
What are the problems with cardiac glycosides?
- Can be blocked by atropine (increased vagal output)
- Uncoordinated arrhythmias can arise
- Low therapeutic index - 50-60% of toxic dose,
- every patient must be titrated
What are the signs of digoxin toxicity?
- Bradycardia - decreased cardiac output
- Extra beats (extrasystoles)
- Causes arrhythmias
- GI effects - nausea/vomiting, salivation, diarrhea
- CNS - headache, fatigue, drowsy, green/yellowish aura
What is the antidote for digoxin toxicity?
Digoxin immune fab (Digibind, Digifab)
How can you treat digoxin toxicity?
- Potassium chloride and anti-arrhythmic medications
Remember - lowering potassium potentiates the effects of ________, and increases potassium acts like an antidote of toxicity which is _________?
- Digitalis
- Digoxin immune fab
