Positive Inotropic Drugs In Heart Failure (51) Flashcards by Ella Thorsteinson

Heart failure

Heart is unable to pump enough blood to meet the body’s metabolic needs

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Symptoms of heart failure depend on

Cardiac area affected
-left ventricular failure (edema)
-right ventricular failure (coughing up blood)

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Inotropic drugs

Increase the force of myocardial contraction
-used in treatment of heart failure

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Three types of inotropic drugs

-cardiac glycosides
-sympathomimetic drugs
-phosphodiesterase inhibitors

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Cardiac glycosides example

Digoxin

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Sympathomimetic drugs example

-dobutamine
-dopamine

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What other types of drugs are used in heart failure

-diuretics (K losing drugs)
-b adreoceptor antagonists
-RAAS drugs (ace inhibitors, arbs, aldosterone antagonists)
-vasodilators
-organic nitrates

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Causes of heart failure

-cardiac muscle defect
-supraventricular dysrhythmias
-other

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Causes of heart failure: cardiac muscle defect

-MI
-congenital

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Causes of heart failure: supraventricular dysrhythmias

Atrial fibrillation and atrial flutter

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Causes of heart failure: other defects beyond cardiac muscle

-CAD
-hypertension/pulmonary hypertension
-valve deficiency
-diabetes mellitus

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Outcomes of heart failure

-structural changes in cardiac muscle or connective tissue in ventricular wall

-functional changes in the ability of the ventricle pump blood

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Symptoms of heart failure

-reflex tachycardia
-edema
-elevated venous pressure
-dyspnea
-weakness
-enlarged heart

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Drug effects on cardiac muscle: inotropic

Force of muscular contractions
-positive or negative

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Drug effects on cardiac muscle: chronotropic

Rate of the heartbeat
-positive or negative

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Drug effects on cardiac muscle: dromotropic

Conduction speed of electrical impulses
-positive or negative

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Digoxin is originally obtained from

Digitalis plant
-foxglove

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Digoxin mechanism of action

Induces an increase in intracellular sodium that will drive an influx of calcium in the heart and cause an increase in contractility

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Digoxin inhibits

The Na/K ATPase enzyme
-increasing sodium

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Three Ss of digoxin action

-strengthens
-slows
-slows

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Three Ss of digoxin action: strengthens

Positive inotropic effect
-inc force of myocardial contraction

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Three Ss of digoxin action: slows 1

Negative chronotropic effect
-reduced heart rate at SA node

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Three Ss of digoxin action: slows 2

Negative dromotropic effect
-decreases AV nodal conduction and other effects

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Digoxin effects: increases

-stroke volume (cardiac output)
-coronary circulation
-diuresis due to improved kidney perfusion

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Digoxin effects: decreases

-venous BP -vein engorgement

Digoxin effects: relieves symptoms of

-paroxysmal/nocturnal dyspnea -cough -cyanosis ***DOES NOT SOLVE JUST RELIEVE

Indications of digoxin

-heart failure -supraventricular dysrhythmias (a fib/a flutter)

Different mg a tablet of digoxin

0.25, 0.125, 0.0625mg

Supraventricular dysrhythmias are a problem located

Above the ventricle

AE of digoxin:

-narrow therapeutic window -low potassium levels increase toxicity -general malaise -GI -coloured vision -cardiovascular

AE of digoxin: narrow therapeutic window

-toxicity slightly above therapeutic plasma level -drug levels must be monitored

AE of digoxin: low potassium levels increase toxicity

-low Mg also increases toxicity -electrolyte levels must be monitored

AE of digoxin: generalized malaise

“Just dont feel right” -fatigue, weakness, confusion

AE of digoxin: GI

Anorexia, nausea, vomiting, diarrhea -earlier signs of AE

AE of digoxin: coloured vision

Seeing yellow, green, purple, halo vision, flickering lights

AE of digoxin: cardiovascular

Dysrhythmias including bradycardia -or tachycardia

Because of cardiovascular AE, what must be done before administering digoxin

Must take apical pulse, minimum of 60 b/m -if lower hold, recheck, notify prescriber

Digoxin toxicity

Quite common medication problem -accidental, or intention overdose

Symptoms of digoxin toxicity

-change in renal function = decreased -episode of diarrhea

How dangerous is digoxin toxicity

It is life threatening

How do you treat digoxin toxicity

Digoxin immune Fab therapy

Digoxin immune fab therapy

Used as antidote to rapidly reduce toxicity -binds to digoxin

Binding to digoxin can cause

Life threatening cardiac dysrhytmias

Factors increasing risk of digoxin toxicity

-low K -renal dysfunction -herbal products -hypokalemia -increase absorption of digoxin -decreases renal clearance of digoxin

Factors increasing risk of digoxin toxicity: low K

Loop diuretic furosemide -high ca, low magnesium

Factors increasing risk of digoxin toxicity: renal dysfunction

Elderly, hypothyroid

Factors increasing risk of digoxin toxicity: herbal products

Ginkgo, St. John’s Wort

Factors increasing risk of digoxin toxicity: hypokalemia

Lead to hypokalemia then to toxicity -amphotericin B, furosemide, thiazides, laxatives, steroids

Factors increasing risk of digoxin toxicity: increase absorption of digoxin

Anticholinergics

Factors increasing risk of digoxin toxicity: decreases renal clearance of digoxin

Plasma x2 -quinidine, verapamil

Upon giving digoxin, clinical parameters need to be asses….

-apical pulse -serum labs

Upon giving digoxin, clinical parameters need to be asses: apical pulse

NOT RADIAL -for one full minute

Upon giving digoxin, clinical parameters need to be asses: serum labs

Potassium, sodium, magnesium, calcium, renal, liver function studies

Apical pulse should be

<60 or >120 betas/min 0r less than 90 in an infant

What do you do if pulse is <60 or >120

-hold dose, recheck in one hour -notify prescriber, a slow rate could be sign of toxicity

Hold digoxin dose and notify prescriber IF

Client experiences signs/symptoms of toxicity -anorexia, nausea, vomiting, diarrhea, visual disturbances

Sympathomimetic drugs are administered

IV infusion only -due to rapid metabolism

Sympathomimetic drugs activate

Cardiac B1 adrenoceptors -increase cardiac contractility -only in severe and acute HF

Two types of sympathomimetic drugs

-dobutamine -dopamine

Phosphodiesterase inhibitors

Inhibit enzyme phosphodiesterase

Phosphodiesterase inhibitors create

Positive inotropic response -positive lusitropic effects

Phosphodiesterase inhibitors two agents

Milrinone

Indications of Phosphodiesterase inhibitors

Short term management of heart failure

Phosphodiesterase inhibitors are given when client has

Not responses to treatment with digoxin, diuretics, and or vasodilators

Phosphodiesterase inhibitors are often given as

Weekly six hour IV infusions -improve QOL -decreased readmissions for heart failure episodes

Monitor for therapeutic effects of Phosphodiesterase inhibitors

-inc urinary output -dec edema, SOB, fatigue, rales (crackles) -resolving of paroxysmal nocturnal dyspnea -improved peripheral pulses, skin color, temperature