Lecture Notes 1
CARDIAC GLYCOSIDES AND HEART FAILURE (Chapter 21, Page 163)
Cardiac glycosides= Prototype medication: Digoxin
Purpose
• Positive inotropic effect= Increases contraction
• Negative chronotropic effect= Decreases heart rate: Apical pulse has to be at least 60 before you
give the medication
▪ Have to count for the full minute ▪ Fifth intercostal space,
midclavicular line
• Negative dromotropic effect= Slows down rhythm
Therapeutic uses
• Treatment of heart failure • Dysrhythmias (atrial fibrillation) = Because
of the negative dromotropic effect
Complications: Digoxin toxicity= Therapeutic level of digoxin: 0.8-2.0. Antidote: Digibind. Know the signs and
symptoms of digoxin toxicity:
▪ First sign is anorexia (loss of appetite) ➢ If the patient is hyperkalemic, digoxin is
▪ Nausea/vomiting less effective
▪ Diarrhea ➢ Potassium levels need to be within
▪ Bradycardia the normal range
▪ Hypotension ▪ Blurring of vision
▪ Hypokalemia ▪ Diplopia (double vision)
➢ CHF patients are usually on loop ▪ Xeropthalmia (yellowish-green halos
diuretics which can result in around objects)
hypokalemia as well ▪ Dysrhythmias
➢ If a patient is hypokalemic, they are
at risk for digoxin toxicity
Interactions
• Cimetidine (Histamine2-receptor antagonist) • Quinidine increases the risk of digoxin toxicity
increases digoxin levels • Verapamil increases plasma levels of digoxin
Nursing Administration
• IV digoxin has to be over at least five minutes • Monitor lab values, vital signs, potassium levels,
therapeutic levels
Adrenergic agonists= Prototype medication: epinephrine, dopamine, dobutamine. Know which of these drugs act
on which receptors
• Epinephrine: alpha1, beta1, beta2 • Dobutamine: beta1
• Dopamine: beta1, beta2 • Please someone double-check this
Purpose:
• Increase blood pressure • All these drugs will increase the heart rate,
• Bronchodilation but that’s not their purpose
• They make the heart pump
Epinephrine= Given for anaphylactic shock and cardiac
arrest when your heart’s not working, your
• It causes vasoconstriction and bronchodilation blood pressure is zero.
• When given for cardiac arrest, give it as fast • Don’t give IV epinephrine to a patient who’s
as possible healthy and walking and talking – the
• And you have to do CPR when you give the vasoconstriction will cause a hypertensive
epinephrine, otherwise, it won’t go crisis
anywhere. Because the heart’s not working=
Note that
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, Dopamine= When given as a low dose, its purpose is to increase renal perfusion. It dilates the renal blood vessels.
• Usually the dose is 5mcg/min. • These patients can stay in the telemetry unit
• We don’t titrate this dose
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