Transcript Pharmacology and the Nursing Process, 4th ed. Lilley/Harrington

Chapter 24
Lilley
Heart Failure Drugs
Conduction System of the Heart
The New York Heart Association
Classification of HF
Class I
Class II
Class III
Class IV
Drug Therapy for Heart Failure
•Positive inotropic drugs
Increase the force of myocardial contraction
•Positive chronotropic drugs
Increase heart rate
•Positive dromotropic drugs
Accelerate cardiac conduction
Drug Therapy for Heart Failure (cont’d)
ACE inhibitors
Angiotensin II receptor blockers
Beta blockers
Aldosterone antagonists
B-type natriuretic peptides
Phosphodiesterase inhibitors
Cardiac glycosides
ACE Inhibitors
Prevent sodium and water resorption by inhibiting
aldosterone secretion
Diuresis results, which decreases preload, or the left
ventricular end-volume, and the work of the heart
Examples: lisinopril, enalapril, fosinopril, quinapril,
captopril, ramipril, trandolapril, and perindopril
Angiotensin II Receptor Blockers (ARBs)
Potent vasodilators; decrease systemic vascular
resistance (afterload)
Examples: valsartan (Diovan), candesartan (Atacand),
eprosartan (Teveten), irbesartan (Avapro), telmisartan
(Micardis), olmesartan (Benicar), and losartan (Cozaar)
All ARBs are similar in action
Beta Blockers
Beta blockers work by reducing or blocking sympathetic
nervous system stimulation to the heart and the heart’s
conduction system
Reduced heart rate, delayed AV node conduction,
reduced myocardial contractility, and decreased
myocardial automaticity result
Examples: metoprolol, carvedilol (Coreg)
Aldosterone Antagonist
spironolactone (Aldactone)
Potassium-sparing diuretic
Also acts as an aldosterone antagonist, which has been shown
to reduce the symptoms of heart failure
eplerenone (Inspra)
Selective aldosterone blocker
Miscellaneous Drugs to Treat
Heart Failure
hydralazine/isosorbide dinitrate (BiDil)
First drug approved for a specific ethnic group, namely African
Americans
dobutamine
Beta1-selective vasoactive adrenergic drug
Structurally similar to dopamine
B-type Natriuretic Peptides
nesiritide (Natrecor)
Used in the intensive care setting as a final effort to treat
severe, life-threatening heart failure, often in combination with
several other cardiostimulatory medications
B-type Natriuretic Peptides:
Mechanism of Action
Effects include diuresis (urinary fluid loss), natriuresis
(urinary sodium loss), and vasodilation
Vasodilating effects on both arteries and veins
Indirectly increases cardiac output
Suppresses renin-angiotensin system
Classroom Response Question
Which patient is the best candidate to receive nesiritide
therapy?
A. A patient with atrial fibrillation who has not responded to
other drugs
B. A patient needing initial treatment for heart failure
C. A patient with reduced cardiac output
D. A patient with acutely decompensated heart failure who has
dyspnea at rest
B-type Natriuretic Peptides:
Adverse Effects
Hypotension
Dysrhythmia
Headache
Abdominal pain
Phosphodiesterase Inhibitors
Work by inhibiting the enzyme phosphodiesterase
Results in:
Positive inotropic response
Vasodilation
milrinone (Primacor)
Phosphodiesterase Inhibitors:
Indications
Short-term management of heart failure
Given when patient does not respond to treatment
with digoxin, diuretics, and/or vasodilators
AHA and ACC advise against long-term infusions
Phosphodiesterase Inhibitors:
Adverse Effects
milrinone
Dysrhythmia
Hypotension
Angina (chest pain)
Hypokalemia
Tremor
Thrombocytopenia
Cardiac Glycosides
No longer used as first-line treatment
Originally obtained from Digitalis plant, foxglove
Digoxin is the prototype
Used in heart failure and to control ventricular
response to atrial fibrillation or flutter
Cardiac Glycosides:
Mechanism of Action
Increase myocardial contractility
Change electrical conduction properties of the heart
Decrease rate of electrical conduction
Prolong the refractory period
Area between SA node and AV node
Cardiac Glycosides:
Drug Effects
Positive inotropic effect
Increased force and velocity of myocardial contraction
(without an increase in oxygen consumption)
Negative chronotropic effect
Reduced heart rate
Negative dromotropic effect
Decreased automaticity at SA node, decreased AV nodal
conduction, and other effects
Digoxin Effects
The probable mechanism of action for the inotropic effect of digitalis is
inhibition of the membrane-bound Na+/K+-ATPase pump; when this occurs,
Na+ increases in the cell, the exchange of Na+ for Ca2+ is augmented, and
calcium influx is increased. The increased intracellular calcium in turn leads
to increased release of Ca2+ from the sarcoplasmic reticulum and increased
contractility of the cardiac muscle.
Digitalis also has a negative chronotropic effect due to decreased conduction
velocity in the atrioventricular (AV) node
Cardiac Glycosides:
Drug Effects (cont’d)
Increased stroke volume
Reduction in heart size during diastole
Decrease in venous BP and vein engorgement
Increase in coronary circulation
Promotion of diuresis because of improved blood
circulation
Palliation of exertional and paroxysmal nocturnal
dyspnea, cough, and cyanosis
Cardiac Glycosides:
Indications
• Heart failure
• Supraventricular dysrhythmias
• Atrial fibrillation and atrial flutter
Classroom Response Question
A patient is in the emergency department with new onset atrial
fibrillation. Which order for digoxin would most likely have the
fastest therapeutic effect?
A. Digoxin 0.25 mg PO daily
B. Digoxin 1 mg PO now, then 0.25 mg PO daily
C. Digoxin 0.5 mg IV push daily
D. Digoxin 1 mg IV push now, then 0.25 mg IV daily
Cardiac Glycosides:
Adverse Effects
Digoxin (Lanoxin)
Very narrow therapeutic window
Drug levels must be monitored
0.5 to 2 ng/mL
Low potassium levels increase its toxicity
Electrolyte levels must be monitored
Cardiovascular
Dysrhythmias, including bradycardia or tachycardia
CNS
Headaches, fatigue, malaise, confusion, convulsions
Eye
Colored vision (seeing green, yellow, purple), halo vision, flickering lights
GI
Anorexia, nausea, vomiting, diarrhea
Digoxin Toxicity
For hyperkalemia <5 mEq/L, use insulin plus glucose, and sodium
bicarbonate if the patient is acidotic
Treatment with digoxin Fab fragments is indicated for a K + level
greater than 5 mEq/L
Hemodialysis may be necessary for uncontrolled hyperkalemia
Correct hypokalemia (usually in chronic intoxication)
Concomitant hypomagnesemia may result in refractory
hypokalemia
Digibind Therapy Continued
for Digoxin Toxicity
Toxicity During Chronic Therapy
Acute distress or for whom a serum digoxin concentration is not available: Administer 6 vials
Renal Impairment
Dose adjustment not necessary but use caution as digoxin immune Fab complex is renally eliminated
Administration
Administer by IV infusion over 15-30 minutes (see IV information)
May be given IVP for life-threatening dysrhythmias
Other Indications & Uses
For life-threatening dysrhythmias or hypotension unresponsive to other measures caused by digoxin,
digitoxin or related toxins (ie, foxglove)
[K+] >5 mEq/L in setting of severe digoxin intoxication, especially if increased creatinine
Digibind Adverse Effects?
Med Adverse Effects
Effects (due to ?) include exacerbation of HF, rapid
ventricular response in patients with a.fib; postural
hypotension
Classroom Response Question
A patient is receiving digoxin 0.25 mg daily as part of treatment
for heart failure. The nurse assesses the patient before
medication administration. Which assessment finding would be
of most concern?
A. Apical heart rate of 58 beats/min
B. Blood Pressure 130/70
C. Serum potassium level of 2.9 mEq/L
D. Serum digoxin level of 0.8 ng/mL
Heart Failure Drugs:
Nursing Implications
Assess history, drug allergies, contraindications
Assess clinical parameters, including:
BP
Apical pulse for 1 full minute
Heart sounds, breath sounds
For apical pulse less than 60 or greater than 100 beats/min
Hold dose
Notify prescriber
Heart Failure Drugs:
Nursing Implications (cont’d)
Assess clinical parameters (cont’d)
• Weight, I&O measures
• ECG
• Serum labs: potassium, sodium, magnesium, calcium, renal,
and liver function studies
Heart Failure Drugs:
Nursing Implications (cont’d)
Hold dose and notify prescriber if patient experiences
signs/symptoms of toxicity
• Anorexia, nausea, vomiting, diarrhea
• Visual disturbances (blurred vision, seeing ?)
Xanthopsia
Ocular manifestations include xanthopsia (seeing yellow). Most
experts believe that the famous artist Vincent van Gogh was
using foxglove (the flower that digoxin is derived from) and this
explains his yellow paintings toward the end of his life. See two
of the paintings below:
Van Gogh –yellow tint to
paintings, also painted halos
Heart Failure Drugs:
Nursing Implications (cont’d)
Check dosage forms carefully, and follow instructions
for administering
Avoid giving digoxin with high-fiber foods (fiber binds
with digitalis)
Patients should immediately report a weight gain of 2 lb
or more in 1 day or 5 lb or more in 1 week
Heart Failure Drugs:
Nursing Implications (cont’d)
Nesiritide or milrinone
Use an infusion pump
Monitor I&O, heart rate and rhythm, BP, daily weights,
respirations, and so on
Heart Failure Drugs:
Nursing Implications (cont’d)
Monitor for therapeutic effects
Increased urinary output
Decreased edema, shortness of breath, dyspnea, crackles,
fatigue
Resolution of paroxysmal nocturnal dyspnea
Improved peripheral pulses, skin color, temperature
Monitor for adverse effects
Case Study
A patient with a history of heart failure presents to the
emergency department with difficulty breathing, cough,
and edema of the lower extremities. The nurse
anticipates administration of which type of medication?
A. Negative chronotrope
B. Positive inotrope
C. Negative inotrope
D. Diuretic
Case Study (cont’d)
The patient is prescribed an ACE inhibitor. The nurse
understands the primary mechanism by which the ACE
inhibitors exert their therapeutic effect in a patient in
heart failure is:
A. to inhibit catecholamine release.
B. to inhibit acetylcholine release.
C. to inhibit aldosterone secretion.
D. to prevent vagal stimulation.
Case Study (cont’d)
The patient is discharged home and returns to the
emergency department 4 days later. The patient is
admitted to the intensive care unit with acute
decompensated heart failure with dyspnea at rest. The
nurse anticipates administration of which medication?
A. atropine
B. carvedilol (Coreg)
C. lisinopril (Prinivil)
D. nesiritide (Natrecor)