Transcript Cardiac Stimulants and Depressants

Antiarrhythmic Agents:
Cardiac Stimulants
and Depressants
The Heart
 Four-chambered 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
Generates and conducts electrical impulses
Heart rate is controlled by the autonomic nervous
system
17 - 2
The Heart
 Main pacemakers of heart:
 Sinoatrial node: 60-100 bpm; primary
pacemaker
 Atrioventricular node: Connects atria
and ventricles; 40-60 bpm
 Bundle of His and Purkinje fibers:
carry electrical impulses from AV node
to complete ventricle rate pacing; 1540 bpm
17 - 3
Cardiac medications
 Increase /decrease the force of the
myocardial contraction
 Increase / decrease the heart rate
 Increase / decrease the conduction of
electrical impulses through the
myocardium
17 - 4
Congestive Heart Failure (CHF)
Cardiac glycosides
 -Digoxin
 -Treat arrhythmias
17 - 5
Cardiac Glycosides
 Derived from natural sources; treatment for
heart failure:
 cardiac distention-inability to pump the
full blood volume
 cardiac hypertrophy-prolonged stretching
 sodium and water retention-decreased
renal blood flow
 Results in weight gain, edema, shortness of
breath, and pulmonary congestion
17 - 6
Digoxin
 Decreases electrical conduction
 Negative Dromatotropic Effect
 Increases time spent in diastole
 Increases the force of the myocardial
contraction
 Positive inotropic action
 End result: slows and strengthens
contractions
17 - 7
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 - 8
Digoxin
 Low therapeutic index
 Toxicity can be life-threatening; occurs
in 10-20% of patients
 Many drug-drug, drug herbal
interactions
 Routine monitoring of serum
potassium and digoxin levels
17 - 9
Digoxin: Adverse Effects
 Gastrointestinal effects
 Nausea and vomiting
 Anorexia
 Diarrhea
 Cardiac effects
 Cardiac arrhythmias
 Neurological effects
17 - 10
Cardiac Glycoside Toxicity
 Predispose to cardiac glycoside toxicity
 Hypokalemia
 Renal impairment
 Rapid IV administration
17 - 11
Cardiac Glycoside Toxicity
 Treatment
 Stop the drug
 Physical assessment
 Check potassium level
 Administer if needed
 Monitor heart rate
 Administer antiarrhythmics
17 - 12
Nursing Considerations
 Apical pulse for 1 minute. Hold if HR < 60
bpm
 Report changes in heart rhythm
 Assess for symptoms of toxicity
 Monitor digoxin blood levels
 Monitor for drug-drug and drug-herbal
interactions
 Educate : signs of toxicity and how to
monitor pulse rate
.
17 - 13
Antiarrhythmic and Antidysrhythmic Drugs
 Grouped together according to their similar
actions
 Work three ways:
 Decrease automaticity of cardiac tissues
in the ectopic sites
 Alter rate of conduction
 Alter refractory period of cardiac muscle
between consecutive contractions
17 - 14
Antiarrythmic Agents
 Dependent on:
 type of dysrhythmia
 presence of other conditions
 safety of the drug
 onset and/or duration of drug action
 Administered IV until patient
stabilized, then oral agents given
 Arranged into classes
17 - 15
Antidysrhythmic Medications
 Class 1 (1A, 1B, 1C): decrease the influx of
sodium ions, stabilizing membranes
 Class 2: decrease contractility, B/P, AV
node conduction
 Class 3: Prolong action potential,
refractory period
 Class 4: Decrease myocardial
contractility, 02 demand
17 - 16
Antidysrhythmics
 Quinidine gluconate – Class 1
 Lidocaine – Class 1B
 Dilantin – Class 1B
 Propranolol – Class 2
 Verapamil HCL – Class 4
 Digoxin – Class 4
17 - 17
Adverse Effects
GI upset
Cardiovascular disorders
Hypersensitivity
Hypotension
Bradycardia
Lightheadedness
17 - 18
Nursing Considerations
 Take patients apical pulse for one
minute
 Record rate and rhythm of the
heartbeat
 Assess allergies
 Monitor blood pressure
 Patient should be supine when
administering IV agents
.
17 - 19
Beta-adrenergic Blocking Agents
Block the hormone epinephrine
Inhibit beta and beta2
sympathetic receptors
Reduce heart rate
Reduces contractility
Slow electrical conduction
Decrease the blood pressure
17 - 20
Beta-Adrenergic Blocking Agents
Adverse effects
 Cause bronchoconstriction
 Can cause heart failure
Examples: propranolol
(Inderal), esmolol, bretylium
tosylate (Bretylol)
17 - 21
Calcium Channel Antagonists
 Reduce the influx of calcium into the
cell:
 Prevention of reversal of spasms of the
coronary blood vessels
 Coronary artery dilation
 Reduction of myocardial oxygen
consumption
 Example: Verapamil
.
17 - 22
Adverse Effects
 Vasodilation may cause:
 Hypotension
 Edema
 Dizziness
 Headache
 Slower myocardial conduction may cause:
 Bradycardia
 Heart failure
 Other effects:
 Constipation, diarrhea, nausea, fatigue
17 - 23
Patient Education
 Ensure understanding of drug regime
 Review signs to report to their health
care provider
 Instruct patient how to take their pulse
 Remind them of the importance for
proper follow-up
 Encourage questions
17 - 24