Download Cardiac Stimulants and Depressants

Chapter 17
Cardiac Stimulants and
Depressants
The Heart


The heart is a four-chamber organ
located in the upper left thoracic cavity.
Purpose


Pumps the blood around the body so that
oxygen and nutrients can be distributed to
all areas of the body
Maintains the blood pressure at an
acceptable level
17 - 2
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antiarrhythmics and Antianginals

Cardiac illnesses


Cardiac stimulants
Cardiac depressants
17 - 3
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Treatment of Heart Failure

Cardiac glycosides


Digoxin
Treat arrhythmias
17 - 4
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Digoxin



Decreases electrical conduction
Prolongs refractory period
Increases the force of the myocardial
contraction

Positive inotropic action
17 - 5
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Digoxin: Dose Considerations



Duration of action
Method of administration
Other





Physical size of the client
Other medications
Renal or hepatic function
Advanced age
Presence of other illnesses
17 - 6
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antiarrhythmics and Antianginals

Require a digitalizing dose


To bring serum levels to a therapeutic level
All glycosides have a low therapeutic level
17 - 7
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antiarrhythmics and Antianginals:
Side Effects

Gastrointestinal effects




Cardiac effects

17 - 8
Nausea and vomiting
Anorexia
Diarrhea
Cardiac arrhythmias
(continues)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
(continued)
Antiarrhythmics and Antianginals:
Side Effects

Neurological effects





Restlessness
Irritability
Drowsiness
Vision changes
Headache
17 - 9
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Cardiac Glycoside Toxicity

Predispose to cardiac glycoside toxicity



17 - 10
Hypokalemia
Renal impairment
Rapid IV administration
(continues)
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
(continued)
Cardiac Glycoside Toxicity

Treatment



Stop the drug
Physical assessment
Check potassium level


Administer if needed
Monitor heart rate

Administer antiarrhythmics
17 - 11
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antiarrhythmic and
Antidysrhythmic Drugs

Grouped together according to their
similar actions
17 - 12
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antiarrhythmics and Antianginals:
Drug Action

Work three ways:



Decrease the automaticity of cardiac
tissues in the ectopic sites
Alter the rate of conduction of electrical
impulses through the heart.
Alter the refractory period of cardiac
muscle between consecutive
contractions
17 - 13
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antidysrhythmic Agents




Group 1, 1A, 1B, 1C: decrease the influx
of sodium ions, stabilizing membranes
Group 2: depress phase 4 in
depolarization
Group 3: prolong repolarization in phase 3
Group 4: depress phase 4 depolarization
and prolong repolarization of phases 1
and 2
17 - 14
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Beta-adrenergic Blocking Agents





Inhibit beta1 and beta2 sympathetic
receptors
Reduce heart rate
Reduce contractility
Decrease supraventricular and
ventricular rhythms
Decrease blood pressure
17 - 15
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Antidysrhythmic Agents

Adverse effects



Cause bronchoconstriction
Cause heart failure
Examples: propanolol (Inderal), esmolol,
bretylium tosylate (Bretylol)
17 - 16
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Calcium Channel Antagonists

Reduce the influx of calcium into the
cell:

Prevention or reversal of spasms of the
coronary blood vessels



Coronary artery dilation
Reduction of myocardial oxygen consumption
Example: verapamil
17 - 17
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Adenosine



Slow conduction through the AV node
Cardioverts paroxysmal
supraventricular tachycardia (PSVT)
Side effects




Facial flushing
Shortness of breath
Headache
Nausea and vomiting
17 - 18
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.
Adrenergic or Sympathomimetic
Drugs


Affect alpha- or beta-adrenergic
receptors
Treat shock




Mimic epinephrine and/or norepinephrine
Cause increase in heart rate
Cause vasoconstriction
Reverse hypotension from shock

Cardiac or trauma
17 - 19
Copyright 2007 Thomson Delmar Learning, a division of Thomson Learning Inc. All rights reserved.