1. Cardiac Stimulants and Depressants
Chapter 17
Cardiac Stimulants and Depressants

2. The heart

3. Cardiac conduction p415

4. Autonomic innervation of the heart

5. Aspects of cardiac function affected by drugs p 415
Inotropic effects: force of contractions
Chronotropic effects: heart rate
Dromotropic effects: conduction of electrical impulses thru the myocardium
These effects can be positive or negative.

6. Heart failure p416 Characterized by:
Cardiac distention resulting from incomplete ventricle emptying
Cardiac hypertrophy caused by heart’s adaptation to prolonged stretching (enlarged heart)
Sodium and water retention caused by, in part, diminished renal blood flow

7. Symptoms of heart failure p416
Weight gain
Peripheral edema
Shortness of breath
Pulmonary edema

8. Treatment of Heart Failure p416
Cardiac glycosides: prototype: digoxin (Lanoxin)
Positive inotropic action
Negative chronotropic action
Negative dromotropic action
Foxglove plant

9. Digoxin: Dose Considerations p416
Long duration of action
Method of administration
Oral route most preferable
Digitalizing dose IV
To bring serum levels to a therapeutic level
All glycosides have a low therapeutic index

10. Cardiac glycosides: Side Effects p 417,418
Gastrointestinal effects
Nausea and vomiting
Anorexia
Diarrhea
Cardiac effects
Cardiac arrhythmias

11. Cardiac glycosides: Toxicity p417,418
Neurological effects
Restlessness, confusion
Irritability
Drowsiness
Vision changes
Headache

12. Cardiac Glycoside Toxicity p418
10-20% of pt experience toxicity
Predispose to cardiac glycoside toxicity:
Hypokalemia
Renal impairment
Rapid IV administration

13. Cardiac Glycoside Toxicity p418
Treatment
Stop the drug
Physical assessment
Check potassium level
Administer if needed
Monitor heart rate
Administer antiarrhythmics
Digibind (digoxin immune fab)
For life threatening toxicity

14. Nursing considerations when administering cardiac glycosides
P 417 table 17-1
Administer with meals if GI upset occurs
Hold dose and report to PCP for HR < 60 bpm
Hold dose and report for HR > 100 bpm
Observe pt for signs of toxicity, document, report
Monitor labs K+
dig levels

15. Cardiac glycoside teaching
Pt education
teach pt to take radial pulse prior to taking his med
instruct when to hold dose and contact physician
instruct S/S dig toxicity

16. Antiarrhythmics and antidysrhythmics Drug Action p419
Obliterate or diminish rhythm disturbances:
Decrease the automaticity in ectopic sites
Alter dromotropic effects
Alter the refractory period of cardiac muscle between consecutive contractions

17. Table 17-3 p425-428 Antiarrhythmic drugs
Monitor apical pulse for 1 minute prior to drug administration
Record rate and rhythm
Patient should be supine if IV drugs

18. Quinidine gluconate p420, 428 Old antidysrhythmic agent
Depressant of cardiac function
Reduces the excitibility of cardiac muscle to electrical stimulation
Negative chronotropic effect
SA node regains control

19. Quinidine toxic effects p420
Quinidine therapy is discontinued in 1/3 of pt due to toxic effects
GI distress
N&V
anorexia
diarrhea
Cardiovascular disorders: hypotension, AV block
Hypersensitivity
tinnitus
headache
dizziness
impaired vision
vertigo
skin rashes

20. Procainamide (Pronestyl) p421, 427
Cardiac effects are the same as quinidine, but procainamide has fewer adverse cardiovascular effects
Pt that are allergic to “caine” local anesthetics may have a sensitivity to procainamide

21. Lidocaine (Xylocaine) p421, 426
Widely used as a local anesthetic
Has antidysrhythmic properties
Drug of choice for treatment of premature ventricular contractions (PVCs)
Constant EKG monitoring is necessary for all pt during administration of lidocaine as an antidysrhythmic

22. Beta-adrenergic Blocking Agents “beta blockers” (-olol) p423, 427
Inhibit beta1 and beta2 sympathetic receptors
Cardiac effects of beta blockers
negative inotropic effect
negative chronotropic effect
negative dromotropic effect
Decrease arrhythmias
Decrease blood pressure

23. Beta-adrenergic blocking agents
Adverse effects
Cause bronchoconstriction
Contraindications: pt with respiratory disease
Cause heart failure
Contraindications: pt with heart failure
Examples
Propanolol (Inderal) (prototype)
Metoprolol (Lopresor)
Atenolol (Tenormin)

24. Amiodarone HCL (Cordarone) p423 425
Effective in treating dysrythmias
Adverse effect: pulmonary toxicity
Persistent nonproductive cough
Chest pain with deep inhalation
dyspnea

25. Calcium Channel Antagonists “calcium channel blockers” p424, 428
Reduces the influx of calcium into the cell
relaxation of vascular smooth muscle
Coronary artery dilation (treat angina)
Reduction of myocardial oxygen consumption
Lowered blood pressure
Negative dromotropic effect
Negative inotropic effect
Example: verapamil (Calan) prototype

26. Drugs to treat shock p428 Adrenergic Causes increase in heart rate
Causes peripheral vasoconstriction
Reverses hypotension from shock
Anticholinergic
Atropine sulfate
Frequently given to treat bradycardia