Positive Inotropic Drugs in Heart Failure - Ch. 51 Flashcards
What is Heart failure?
The heart is unable to pump enough blood to meet the body’s metabolic needs
What do heart failure symptoms depend on?
Cardiac area affected
- left ventricular failure
-Right ventricular failure
What are Inotropic drugs?
Drugs that increase the force of myocardiac contraction
What are inotropic drugs used for?
Treatment of heart failure
What are the kinds of Inotropic drugs?
Cardiac glycosides
Sympathomimetic drugs
Phosphodiesterase inhibitors
Example of cardiac glycoside?
Digoxin
Examples of Sympathomimetic drugs?
Dobutamine
Dopamine
What are some other drugs used in heart failure?
Diuretics (K losing)
Beta-adrenoceptor antagonists
RAAS drugs (ACEIS, ARBs, Aldosterone antagonists)
Vasodilators (hrydralazine)
Organic nitrates (isosorbide dinitrate, nitroglycerin)
What causes heart failure to occur?
Cardiac muscle defect
Supraventricular dysrhythmias
Other defects beyond cardiac muscle
What cardiac muscle defects cause HF?
MI
Congenital
What Supraventricular dysrhythmias cause HF?
Atrial fibrillation
Atrial flutter
What other defects beyond cardiac muscle cause HF?
Coronary artery disease -ischemia
Hypertension/pulmonary hypertension
valve deficiency
Diabetes mellitus
What are the outcomes of HF?
Structural changes in cardiac muscle/connective tissue in ventricular wall
Functional changes in the ability of the ventricle to pump blood
What are symptoms of heart failure?
Reflex tachycardia
Edema
Elevated venous pressure
Dyspnea
Weakness
Cardiomegaly
What are inotropic drug effects on cardiac muscle?
Positive or negative force of muscualr contractions
What are chronotropic drug effects on cardiac muscle?
Positive or negative rate of the heartbeat
What are the dromotropic drug effects on cardiac muscle?
Positive or negative conduction speed of electrical impulses
Where were cardiac glycosides (digoxin) originally obtained from?
Digitalis plant (foxglove)
What are 3 S’s of Digoxin action?
Strengthens
Slows
Slows
What is “strengthens” in digoxin action?
Positive inotropic effect
-increase in force of myocardiac contraction
What is the 1st “Slows” in digoxin action?
Negative chronotropic effect
-reduced heart rate at SA node
What is the 2nd “Slows” in digoxin action?
Negative dromotropic effect
-Decreases AV nodal conduction
What are the effects of digoxin?
↑stroke volume and cardiac output
↓ venous BP and vein engorgment
↑ coronary circulation
Promote diuresis (due to improve kidney perfusion)
Palliation of exertional, paroxysmal and
nocturnal dyspnea, cough, and cyanosis
What is digoxin used for?
Heart failure
Supraventricular dysrhythmias (Afib and flutter)
How is Digoxin supplied?
0.25mg, 0.125mg, 0.0625 mg/tablet
What adverse effects are associated with Digoxin?
Narrow therapeutic window
Low potassium and Mg levels increase toxcity
Generalized malaise
GI disturbances
Colored vision
CV effects
What is the narrow therapeutic index of digoxin?
Toxicity is slightly above therapeutic plasma level
-drugs leves must be monitored
What is generalized malaise?
“just don’t feel right”
Fatigue, weakness, confusion
What GI disturbanced are caused by digoxin?
Anorexia, nausea, vomiting, diarrhea
What is colored vision?
Seeing yellow, green, purple, halo vision, flickering lights
What CV adverse effects are caused by digoxin?
Dysrythmias including bradycardia
What must you take to monitor for CV adverse effects associated with digoxin?
Take apical pulse
-Minimum 60bpm
What is digoxin toxicity?
Common medication problem,can be life threatning
Accidental or intention overdose
Change in renal function (decreased elimination)
Diarrhea episodes
-Reduce or stop dosing
What is Digoxin immune Fab (Digibind) therapy
Used as an antidote to rapidly reduce digoxin toxcity
How does Digoxin immune Fab (Digibind) therapy work?
Binds to digoxin to stop life-threatning cardiac dysrythmias
What factors increase risk of digoxin toxicity?
Low K (e.g, Furosemide loop diuretic)
High Calcium
Low magnesium
Renal dysfunction
Elderly
Hypothyroid
Herbal products
Drugs
What herbal products increase risk of digoxin toxicity?
Ginkgo
St. Johns Wort
What ways do drugs increase risk of digoxin toxicity?
Lead to hypokalemia then toxicity
Increase absorption of digoxin
Decreases renal clearance of digoxin (Plasma x2)
What drugs lead to hypokalemia then to digoxin toxicity?
Amphotericin B, furosemide, thiazides, laxatives,
steroids
What drugs Increase absorption of digoxin and cause digoxin toxicity?
anticholinergics
What drugs decrease renal clearance of digoxin and lead to digoxin toxicity?
Quinidine
Verapamil
What serum labs need to be assessed for a client on digoxin?
Potassium
Sodium
Magnesium
Calsium
Renal and liver function studies
What should the apical pulse (not radial) of someone on digoxin be?
<60 or >120 bpm
-less than 90 in an infant
-Slow rate= sign of toxicity
What signs/symptoms indicate digoxin toxicity? Notify HCP, Hold dose!!!
Anorexia
Nausea
Vomitting
Diarrhea
Visual disturbances: Blurred vision, seeing green or yellow halos around bjects
What is the only way sympathomimetic drugs are administered?
IV infusion only
What do sympathomimetic drugs do?
Activate Beta1-adrenoceptors
-Increase cardiac contractility
What are sympathomimetic drugs used for?
Only in severe or acute HF
What do Phosphodiesterase Inhibitors do?
Inhibit the enzyme Phosphodiesterase and produce a positve inotropic respone amd positive lusitropic effect
What are two phosphodiesterase inhibitor agents?
Milrinone
amrinone
What are Phosphodiesterase Inhibitors used for?
Short-term management of HF
When are Phosphodiesterase Inhibitors given?
When client has not responded to digoxin, diuretics and/or vasodilators
How are Phosphodiesterase Inhibitors administered?
Weekly 6-hour IV infusions
What theraputic effects should be monitored when a client is given a positive inotropic agent?
Increased urinary output (adequate fluids important)
Decreased edema, shortness of breath (dyspnea), rales (crackles), and fatigue
Resolvinf of paroxysmal nocturnal dyspnea
Improved peripheral pulses, skin colour and temperature
