Agents for Treating HF

Question 1

Heart Failure - Congestive HF (CHF)

Answer 1

Definition: Condition in which the heart fails to effectively pump blood throughout the body
Primary Treatment: Allows the heart muscle to contract more efficiently in an effort to bring the system back into balance
Causes: Usually involves dysfunction of the cardiac muscle, of which the sarcomere is the basic unit. HF can occur with any of the disorders that damage or overwork the heart muscle - Coronary Artery Disease (CAD), cardiomyopathy, HTN, Valvular heart disease

Question 2

Underlying problems in HF involving Muscle function

Answer 2

Muscle Damage: Atherosclerosis or cardiomyopathy
Increase in workload to maintain an efficient output: HTN or valvular disease
Structural Abnormality: Congenital cardiac defects

Question 3

Signs and Symptoms of CHF: Right-Sided HF

Answer 3

Elevated jugular venous pressure
Splenomegaly
Hepatomegaly
Decreased renal perfusion when upright; increased renal perfusion when supine (nocturia)
Pitting Edema
weakness/fatigue

Question 4

Signs and Symptoms of CHF - Left Sided HF

Answer 4

Anxiety
Tachypnea, dyspnea, orthopnea, hemoptysis, rales
Cardiomegaly, S3 increased heart rate
GI Upset, nausea, abdominal pain
Decreased peripheral pulses, hypoxia

Question 5

Treatments for CHF

Answer 5

Cardiotonic (inotropic) drugs: Cardiac glycosides, phosphodiesterase inhibitors, HCN Blocker

Question 6

Children

Use of Cardiotonic Agents across the lifespan

Answer 6

Digoxin used for heart defects and related cardiac problems
Dosage should be double checked by another nurse
Monitor closely for digitalis toxicity
Phosphodiesterase inhibitors and HCN blockers are not recommended

Question 7

Adults

Use of cardiotonic agents across the lifespan

Answer 7

Instruct to take own pulse
Daily weights
Avoid switching between brands of digoxin
Avoid in pregnancy and lactation

Question 8

Older Adults

Use of cardiotonic agents across the lifespan

Answer 8

More susceptible to digitalis toxicity
Adjust dose for renal impairment
Instruct to take own pulse

Question 9

Cardiac Glycosides - action/indications

Answer 9

Action: Increases intracellular calcium, allows more calcium to enter the myocardial cell during depolarization; positive inotropic effect, increased renal perfusion with a diuretic effect and decrease in renin release, and slowed conduction through the AV node. Increases force of myocardial contraction, cardiac output and renal perfusion and output and decreases blood volume to slow heart rate and conduction velocity through the AV node
Indications: HF, atrial fibrillation
Drug: Digoxin

Question 10

Cardiac Glycosides - adverse effects, contraindications/caution, interactions

Answer 10

Adverse effects: Headache, weakness, drowsiness and vision changes; GI Upset and anorexia; Arrhythmia development
Contraindications: Allergy, ventricular tachycardia or fibrillation, heart block or sick sinus syndrome; idiopathic hypertrophic subaortic stenosis; acute MI, renal insufficiency and electrolyte abnormalities
Caution: Pregnancy/lactation; pediatric and geriatric patients
DDIs: Verapamil, amiodarone, quinidine, quinine, erythromycin, tetracycline or cyclosporine; potassium losing diuretics; cholestyramine, charcoal, colestipol, bleomycin, cyclophosphamide, or methotrexate

Question 11

Cardiac Glycosides: Nursing Considerations

Answer 11

Assess: History and physical exam, known allergies, impaired kidney function, ventricular tachycardia, heart block, sick sinus syndrome or IHSS; electrolyte abnormalities, weight, cardiac status, skin and mucus membranes, affect, orientation, reflexes; LS, abdomen and urinary output and appropriate lab values
Nursing Diagnoses: Risk for imbalanced fluid volume related to increased renal perfusion secondary to the effects of the drug; decreased cardiac output related to ineffective cardiac muscle function; ineffective tissue perfusion r/t change in cardiac output; impaired gas exchange r/t changes in cardiac output; deficient knowledge r/t prescribed drug therapy
Implementation: monitor apical pulse for one full minute before administration, monitor pulse for any change in quality or rhythm, administer IV doses slowly over at least 5 minutes, avoid IM administration, arrange for the patient to be weighted at the same time each day in the same clothes, avoid administering the oral drug with food or antacids, maintain emergency equipment on standby (potassium salts, lidocaine, phenytoin, atropine, and a cardiac monitor), obtain digoxin level as ordered and monitor patient for therapeutic digoxin level (0.5-2 ng/ml)
Evaluation: monitor patient response to the drug (improvement in signs and symptoms of HF, resolution of atrial arrhythmias, serum digoxin level of 0.5-2 ng/ml); monitor for adverse effects; evaluate effectiveness of teaching plan and compliance with regimen

Question 12

Digoxin

Answer 12

Indications: Treatment of HF, atrial fibrillation
Actions: Increases intracellular calcium and allows more calcium to enter the myocardial cell during depolarization —> this causes a positive inotropic effect (increased force of contraction), increased renal perfusion with a diuretic effect and decrease in renin release, a negative chronotropic effect (slower heart rate) and slowed conduction through the AV node
Oral: Onset- 30-120 min —> Peak 2-6 h —-> duration 6-8 days
IV: Onset 5-30 min —> Peak 1-5 h —> Duration 4-5 days
T1/2: 30-40 hours; largely excreted unchanged in the urine

Question 13

Phosphodiesterase Inhibitors - Classification/types

Answer 13

Classification: Second class of drugs that act as cardiotonic (inotropic) agents
Types: 
Inamrinone - approved only for use in patients with HF that has not responded to digoxin, diuretics or vasodilators; 
Milrinone - short term management of HF in patients who are receiving digoxin and diuretics

Question 14

Phosphodiesterase Inhibitors - action/indication

Answer 14

Action: Blocks the enzyme phosphodiesterase, leads to an increase in myocardial cell cyclic adenosine monophosphate (cAMP) which increases calcium level sin the cell causing a stronger contraction and prolongs response to sympathetic stimulation —> directly relaxes vascular smooth muscle
Indication: Short term treatment of HF in patients unresponsive to digitalis, diuretics or vasodilators

Question 15

Phosphodiesterase Inhibitors - contraindications/caution, adverse effects, DDIs

Answer 15

Contraindications: Allergy, severe aortic or pulmonic disease, MI, fluid volume deficit and ventricular arrhythmias
Caution: Pregnancy/lactation, elderly
Adverse Effects: Arrhythmias, hypotension, nausea/vomiting, thrombocytopenia, pericarditis, pleuritis, fever, chest pain, burning at injection site
DDIs: furosemide

Question 16

Phosphodiesterase Inhibitors - Nursing Considerations

Answer 16

Assess: History and physical exam; known allergies, acute aortic or pulmonic valvular disease, acute MI or fluid volume deficit and ventricular arrhythmias; pregnancy/lactation; cardiac status and heart sounds; lab results
Nursing Diagnoses: Decreased cardiac output r/t development of arrhythmias or hypotension; risk for injury r/t CNS or CV effects; Ineffective tissue perfusion r/t hypotension, thrombocytopenia or arrhythmias; deficient knowledge r/t drug therapy
Implementation: protect drug from light, monitor pulse and BP frequently during administration, monitor input and output and record daily weight, monitor platelet counts before and regularly during therapy, provide life support equipment on standby
Evaluation: response to drug, adverse effects, compliance with regimen, effectiveness of teaching plan

Question 17

Prototype: Milrinone - Phosphodiesterase inhibitors

Answer 17

Indication: Short term treatment of HF in patients who have not responded to digitalis diuretics or vasodilators
Actions: blocks the enzyme phosphodiesterase which leads to an increase in myocardial cell cAMP, which increases calcium levels in the cell causing a stronger contraction and prolonged response to sympathetic stimulation, directly relaxes vascular smooth muscle
IV: onset immediate —> peak 10 min —> duration 8 h
t1/2: 2.3-3.5 hours, metabolized in the liver and excreted in the urine and feces

Question 18

Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel Blockers (HCN Blockers)

Answer 18

A new class of drugs approved for treatment of patients with chronic HF - ivabradine
Therapeutic Actions and indications: Blocking the HCN's slows the heart's pacemaker, the sinus node, in the re-polarizing phase of the action potential

Question 19

HCN Blockers - contraindications/cautions, adverse effects, DDIs

Answer 19

Contraindications and Cautions: known allergy, active decompensated HF; hypotension; sick sinus syndrome of AV block; resting heart rate under 60 bpm; patients completely depended on a pacemaker and severe hepatic impairment; Caution - atrial fibrillation or moderate heart block
Adverse Effects: Bradycardia, hypertension, atrial fibrillation, luminous phenomena (sudden changes in brightness in parts of the visual field, colored bright lights, image decompensation, multiple images)
DDIs: CYP3A4 inhibitors or inducers, negative chronotropic drugs

Question 20

Ivabradine (HCN Blocker) - Nursing Considerations

Answer 20

Assess: History and physical; known allergy; AV block, decompensated HF, dependence on pacemaker, resting heart rate under 60 bpm, hypotension; severe hepatic impairment or concurrent use of CYP3A4 inhibitors; cardiac status, ECG and appropriate lab values
Nursing Diagnoses: decreased cardiac output r/t development of arrhythmias or hypotension; risk for injury r/t visual or CV effect; ineffective tissue perfusion r/t hypotension or bradycardia; deficient knowledge
Implementation: monitor heart rate and BP regularly, monitor input/output and record daily weight, provide safety measures if visual disturbances occur, thorough patient teaching
Evaluation: patient response to drug, adverse effects, compliance with regimen and effectiveness of teaching plan
PO: Onset rapid —> Peak 1h —> duration 6 h
T1/2: 2.5 hours, metabolized in the liver and intestines, excreted int he urine and feces