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Positive Inotropic AgentsPositive Inotropic Agents

Pharmacology in NursingPharmacology in Nursing

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DefinitionDefinition

Drugs that increase the force of myocardial Drugs that increase the force of myocardial contractioncontraction

Used to treat heart muscle failureUsed to treat heart muscle failure Cardiac glycosidesCardiac glycosides

digoxindigoxin Phosphodiesterase inhibitors ( PDIs)Phosphodiesterase inhibitors ( PDIs)

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Heart FailureHeart Failure

The heart is unable to pump blood in The heart is unable to pump blood in sufficient amounts from the ventricles to meet sufficient amounts from the ventricles to meet the body’s metabolic needsthe body’s metabolic needs

Impairs heart’s ability to fill or eject properlyImpairs heart’s ability to fill or eject properly Symptoms depend on cardiac area affectedSymptoms depend on cardiac area affected

Left ventricular failureLeft ventricular failure Right ventricular failureRight ventricular failure

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What happens when the heart What happens when the heart fails?fails?

Weakened heart is unable to pump blood in Weakened heart is unable to pump blood in sufficient amountssufficient amounts

Decrease in CO, decrease tissue perfusionDecrease in CO, decrease tissue perfusion Compensatory mechanisms help to maintain Compensatory mechanisms help to maintain

CO and arterial blood pressureCO and arterial blood pressure Renin-angiotensin-aldosterone system Renin-angiotensin-aldosterone system

activated as a compensatory mechanismactivated as a compensatory mechanism As cardiac output decreases, SNS releases As cardiac output decreases, SNS releases

catecholamines which increase HR, catecholamines which increase HR, contractility & vasoconstrictioncontractility & vasoconstriction

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What happens when the heart What happens when the heart fails?fails?

As renal perfusion decreases, renin is As renal perfusion decreases, renin is released by kidneyreleased by kidney

Vasoconstriction increases SVR, which Vasoconstriction increases SVR, which increases afterloadincreases afterload

End result, the failing heart must now work End result, the failing heart must now work HARDER to pump bloodHARDER to pump blood

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Heart Failure: CausesHeart Failure: Causes Cardiac defectCardiac defect

Myocardial infarctionMyocardial infarction Valve deficiencyValve deficiency

Defect outside the heartDefect outside the heart Coronary artery disease/HypertensionCoronary artery disease/Hypertension Pulmonary hypertensionPulmonary hypertension DiabetesDiabetes

Supraventricular dysrhythmiasSupraventricular dysrhythmias Atrial fibrillationAtrial fibrillation Atrial flutterAtrial flutter

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Treatment of Heart FailureTreatment of Heart Failure

Block the compensatory mechanismsBlock the compensatory mechanisms Treat underlying conditionsTreat underlying conditions Goal is to decrease SVR, decrease volume,Goal is to decrease SVR, decrease volume, Increase cardiac outputIncrease cardiac output

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Cardiac GlycosidesCardiac Glycosides

Originally obtained from Originally obtained from DigitalisDigitalis plant, plant, foxglovefoxglove

Digoxin is the prototypeDigoxin is the prototype Used in heart failure and to control ventricular Used in heart failure and to control ventricular

response to atrial fibrillation or flutterresponse to atrial fibrillation or flutter

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Cardiac Glycosides:Cardiac Glycosides:Mechanism of ActionMechanism of Action

Increase myocardial contractilityIncrease myocardial contractility Change electrical conduction properties of the heartChange electrical conduction properties of the heart

Decrease rate of electrical conductionDecrease rate of electrical conduction Prolong the refractory periodProlong the refractory period

• Area between SA node and AV nodeArea between SA node and AV node

Result: reduced heart rate and improved cardiac Result: reduced heart rate and improved cardiac

efficiencyefficiency

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Drug Effects:Drug Effects:General TermsGeneral Terms

InotropicInotropic Force or energy of muscular contractionsForce or energy of muscular contractions

ChronotropicChronotropic Rate of the heartbeatRate of the heartbeat

DromotropicDromotropic The conduction of electrical impulsesThe conduction of electrical impulses

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How Positive Inotropic Agents How Positive Inotropic Agents WorkWork

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Cardiac Glycosides:Cardiac Glycosides:Drug EffectsDrug Effects

Positive inotropic effectPositive inotropic effect Increase in force and velocity of myocardial contraction Increase in force and velocity of myocardial contraction

(without an increase in oxygen consumption)(without an increase in oxygen consumption) Negative chronotropic effectNegative chronotropic effect

Reduced heart rateReduced heart rate Negative dromotropic effectNegative dromotropic effect

Decreases automaticity at SA node, decreases AV nodal Decreases automaticity at SA node, decreases AV nodal conduction, and other effectsconduction, and other effects

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Cardiac Glycosides:Cardiac Glycosides:Drug Effects (cont’d)Drug Effects (cont’d)

Increased stroke volumeIncreased stroke volume Reduction in heart size during diastoleReduction in heart size during diastole Decrease in venous BP and vein engorgementDecrease in venous BP and vein engorgement Increase in coronary circulationIncrease in coronary circulation Promotion of diuresis due to improved blood Promotion of diuresis due to improved blood

circulationcirculation Palliation of exertional and paroxysmal nocturnal Palliation of exertional and paroxysmal nocturnal

dyspnea, cough, and cyanosisdyspnea, cough, and cyanosis

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Cardiac Glycosides:Cardiac Glycosides:IndicationsIndications

Heart failureHeart failure Supraventricular dysrhythmiasSupraventricular dysrhythmias

Atrial fibrillation and atrial flutterAtrial fibrillation and atrial flutter

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Heart FailureHeart Failure

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Atrial Fibrillation/FlutterAtrial Fibrillation/Flutter

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Cardiac Glycosides:Cardiac Glycosides:Adverse EffectsAdverse Effects

Digoxin (Lanoxin)Digoxin (Lanoxin) Very narrow therapeutic windowVery narrow therapeutic window Drug levels must be monitoredDrug levels must be monitored Low potassium levels increase its toxicityLow potassium levels increase its toxicity Electrolyte levels must be monitoredElectrolyte levels must be monitored

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Digoxin: Digoxin: Adverse EffectsAdverse Effects

CardiovascularCardiovascular Dysrhythmias, including bradycardia or Dysrhythmias, including bradycardia or

tachycardiatachycardia CNSCNS

Headaches, fatigue, malaise, confusion, Headaches, fatigue, malaise, confusion, convulsionsconvulsions

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Digoxin: Digoxin: Adverse Effects (cont’d)Adverse Effects (cont’d)

EyeEye Colored vision (seeing green, yellow, purple), halo Colored vision (seeing green, yellow, purple), halo

vision, flickering lightsvision, flickering lights GIGI

Anorexia, nausea, vomiting, diarrheaAnorexia, nausea, vomiting, diarrhea

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Digoxin ToxicityDigoxin Toxicity

digoxin immune Fab (Digibind) therapydigoxin immune Fab (Digibind) therapy Hyperkalemia (serum potassium greater than Hyperkalemia (serum potassium greater than

5 mEq/L) in a digitalis-toxic patient5 mEq/L) in a digitalis-toxic patient Life-threatening cardiac dysrhythmiasLife-threatening cardiac dysrhythmias Life-threatening digoxin overdoseLife-threatening digoxin overdose Therapeutic drug level= 0.5 – 2 ng/mlTherapeutic drug level= 0.5 – 2 ng/ml

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Conditions That Are Predisposing Conditions That Are Predisposing to Digoxin Toxicityto Digoxin Toxicity

HypokalemiaHypokalemia Use of cardiac pacemakerUse of cardiac pacemaker Hepatic dysfunctionHepatic dysfunction HypercalcemiaHypercalcemia DysrhythmiasDysrhythmias Hypothyroid, respiratory, or renal diseaseHypothyroid, respiratory, or renal disease Advanced ageAdvanced age

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Dosing DigoxinDosing Digoxin

Adult Digitalizing Dose:Adult Digitalizing Dose:

PO or IV : 1-1.5 mg/day (4 doses)PO or IV : 1-1.5 mg/day (4 doses)

Usual maintenance dose 0.125 mg- 0.5 mg dayUsual maintenance dose 0.125 mg- 0.5 mg day

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Phosphodiesterase InhibitorsPhosphodiesterase Inhibitors

Work by inhibiting the enzyme phosphodiesteraseWork by inhibiting the enzyme phosphodiesterase Results in:Results in:

Positive inotropic responsePositive inotropic response Vasodilation Vasodilation

Two drugs (inodilators)Two drugs (inodilators) Inamrinone (Inocor) and milrinone (Primacor)Inamrinone (Inocor) and milrinone (Primacor)

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Phosphodiesterase Inhibitors:Phosphodiesterase Inhibitors:IndicationsIndications

Short-term management of heart failureShort-term management of heart failure Given when patient has not responded to treatment Given when patient has not responded to treatment

with digoxin, diuretics, and/or vasodilatorswith digoxin, diuretics, and/or vasodilators Often given as weekly 6-hour infusionsOften given as weekly 6-hour infusions

Improved quality of lifeImproved quality of life Decreased readmissions for heart failure episodesDecreased readmissions for heart failure episodes

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Phosphodiesterase Inhibitors:Phosphodiesterase Inhibitors:Adverse EffectsAdverse Effects

Inamrinone (Inocor)Inamrinone (Inocor) Thrombocytopenia, most worrisomeThrombocytopenia, most worrisome Dysrhythmia, nausea, hypotensionDysrhythmia, nausea, hypotension Elevated liver enzymes with long-term useElevated liver enzymes with long-term use

Milrinone (Primacor)Milrinone (Primacor) Dysrhythmia, mainly ventricularDysrhythmia, mainly ventricular Hypotension, angina, hypokalemia, tremor, Hypotension, angina, hypokalemia, tremor,

thrombocytopeniathrombocytopenia

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Cardiostimulatory DrugsCardiostimulatory Drugs

Enhance cardiac function by:Enhance cardiac function by: Increasing heart rateIncreasing heart rate Increasing myocardial contractilityIncreasing myocardial contractility Positive InotropPositive Inotrop

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Beta-adrenoceptor agonistsBeta-adrenoceptor agonists

Sympathomimetic drugs that bind to beta Sympathomimetic drugs that bind to beta receptors located in cardiac nodal tissue, receptors located in cardiac nodal tissue, conducting tissueconducting tissue

Beta-1 & beta-2 adrenoceptor activation Beta-1 & beta-2 adrenoceptor activation stimulates heart rate & contractilitystimulates heart rate & contractility

Net effect: Increase in cardiac outputNet effect: Increase in cardiac output Used to treat heart failure, cardiogenic and Used to treat heart failure, cardiogenic and

circulatory shockcirculatory shock

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Beta-AgonistsBeta-AgonistsCardiac EffectsCardiac Effects

Increase contractililtyIncrease contractililty

Increase heart rateIncrease heart rate

Increase conduction velocityIncrease conduction velocity

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Beta AgonistsBeta AgonistsVascular & Other EffectsVascular & Other Effects

Smooth muscle relaxationSmooth muscle relaxation BronchodilatationBronchodilatation Hepatic glycogenolysisHepatic glycogenolysis Pancreatic release of glucagonPancreatic release of glucagon Renin release by kidneyRenin release by kidney

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Beta-Agonist DrugsBeta-Agonist Drugs

EpinephrineEpinephrine Norepinephrine (Levophed)Norepinephrine (Levophed) DopamineDopamine DobutamineDobutamine IsoproterenolIsoproterenol

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Major Side EffectsMajor Side Effects

ArrhythmiasArrhythmias Increase myocardial demand for oxygenIncrease myocardial demand for oxygen Increase in heart rateIncrease in heart rate Can precipitate anginaCan precipitate angina

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B-type natriuretic peptide B-type natriuretic peptide

New classNew class Nesiritide ( Natrecor)Nesiritide ( Natrecor) Synthetic recombinant version of B-type Synthetic recombinant version of B-type

natriuretic peptidenatriuretic peptide Vasodilating effects on arteries and veinsVasodilating effects on arteries and veins Used in ICU setting as last alternativeUsed in ICU setting as last alternative

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Positive Inotropic Drugs:Positive Inotropic Drugs:Nursing ImplicationsNursing Implications

Assess history, drug allergies, Assess history, drug allergies, contraindicationscontraindications

Assess clinical parameters, including:Assess clinical parameters, including: BPBP Apical pulse for 1 full minuteApical pulse for 1 full minute Heart sounds, breath soundsHeart sounds, breath sounds

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Positive Inotropic Drugs:Positive Inotropic Drugs:Nursing Implications (cont’d)Nursing Implications (cont’d)

Assess clinical parameters (cont'd)Assess clinical parameters (cont'd) Weight, I&O measuresWeight, I&O measures EKGEKG Serum labs: potassium, sodium, magnesium, Serum labs: potassium, sodium, magnesium,

calcium, renal and liver function studiescalcium, renal and liver function studies

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Positive Inotropic Drugs:Positive Inotropic Drugs:Nursing Implications (cont’d)Nursing Implications (cont’d)

Before giving any dose, count apical pulse for Before giving any dose, count apical pulse for 1 full minute1 full minute

For apical pulse less than 60 or greater than For apical pulse less than 60 or greater than 120 beats/minute120 beats/minute Hold doseHold dose Notify prescriberNotify prescriber

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Positive Inotropic Drugs:Positive Inotropic Drugs: Nursing Implications (cont’d)Nursing Implications (cont’d)

Hold dose and notify prescriber if patient Hold dose and notify prescriber if patient experiences signs/symptoms of toxicityexperiences signs/symptoms of toxicity Anorexia, nausea, vomiting, diarrheaAnorexia, nausea, vomiting, diarrhea Visual disturbances (blurred vision, seeing green Visual disturbances (blurred vision, seeing green

or yellow halos around objects)or yellow halos around objects)

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Positive Inotropic Drugs: Positive Inotropic Drugs: Nursing Implications (cont’d)Nursing Implications (cont’d)

Check dosage forms carefully, and follow Check dosage forms carefully, and follow instructions for givinginstructions for giving

Avoid giving digoxin with high-fiber foods Avoid giving digoxin with high-fiber foods (fiber binds with digitalis)(fiber binds with digitalis)

Patients should report immediately a weight Patients should report immediately a weight gain of 2 or more pounds in 1 day or 5 or gain of 2 or more pounds in 1 day or 5 or more pounds in 1 weekmore pounds in 1 week

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Positive Inotropic Drugs: Positive Inotropic Drugs: Nursing Implications (cont’d)Nursing Implications (cont’d)

Inamrinone or MilrinoneInamrinone or Milrinone Use an infusion pumpUse an infusion pump Monitor I&O, heart rate, BP, daily weights, Monitor I&O, heart rate, BP, daily weights,

respirations, etc.respirations, etc. IV InamrinoneIV Inamrinone

Do not mix with dextroseDo not mix with dextrose Solution color is true yellowSolution color is true yellow

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Positive Inotropic Drugs: Positive Inotropic Drugs: Nursing Implications (cont’d) Nursing Implications (cont’d)

Monitor for therapeutic effectsMonitor for therapeutic effects Increased urinary outputIncreased urinary output Decreased edema, shortness of breath, dyspnea, Decreased edema, shortness of breath, dyspnea,

crackles, fatiguecrackles, fatigue Resolving of paroxysmal nocturnal dyspneaResolving of paroxysmal nocturnal dyspnea Improved peripheral pulses, skin color, Improved peripheral pulses, skin color,

temperaturetemperature Monitor for adverse effectsMonitor for adverse effects

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QuestionQuestion

When teaching the patient the signs and When teaching the patient the signs and symptoms of cardiac glycoside toxicity, the symptoms of cardiac glycoside toxicity, the nurse should alert the patient to watch for;nurse should alert the patient to watch for; A. Visual changes such as photophobiaA. Visual changes such as photophobia B. Flickering lights or halos around lightsB. Flickering lights or halos around lights C. dizziness when standing upC. dizziness when standing up D. Increased urine output D. Increased urine output

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QuestionQuestion

During assessment of a patient receiving During assessment of a patient receiving Digoxin, which finding would indicate an Digoxin, which finding would indicate an increased possibility of toxicity?increased possibility of toxicity? A. Apical rate of 62A. Apical rate of 62 B. Digoxin level of 1.5 ng/mlB. Digoxin level of 1.5 ng/ml C. Serum potassium level of 2 mEq/LC. Serum potassium level of 2 mEq/L D. Serum potassium level of 4.8 mEq/LD. Serum potassium level of 4.8 mEq/L

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QuestionQuestion

When monitoring a patient who is receiving When monitoring a patient who is receiving an IV infusion of Inocor, the nurse will look for an IV infusion of Inocor, the nurse will look for which adverse effect?which adverse effect? A. ThrombocytopeniaA. Thrombocytopenia B. ProteinuriaB. Proteinuria C. AnemiaC. Anemia D. Decreased BUN/Creatinine levelsD. Decreased BUN/Creatinine levels

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QuestionQuestion

When administering the daily dose of digoxin When administering the daily dose of digoxin 0.125mg PO to a patient with IDDM who is 0.125mg PO to a patient with IDDM who is now in heart failure, it is most important for now in heart failure, it is most important for the nurse to:the nurse to: A. Give medication with a class of orange juice.A. Give medication with a class of orange juice. B. Monitor the patient for dysrhythmias.B. Monitor the patient for dysrhythmias. C. Administer it 1 hour before the morning dose of C. Administer it 1 hour before the morning dose of

insulin.insulin. D. Withhold dose if the apical heart rate is less D. Withhold dose if the apical heart rate is less

then 80 beats per minute.then 80 beats per minute.

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Case ScenarioCase ScenarioHeart FailureHeart Failure

Mrs. Allen is a 76 year old female admitted Mrs. Allen is a 76 year old female admitted with heart failure. She has been started on with heart failure. She has been started on Digoxin 0.125 mg po. Your initial assessment Digoxin 0.125 mg po. Your initial assessment of this patient revealed the following:of this patient revealed the following:

AAOx1AAOx1 Vitals: P 110, RR 33, BP 110/56 SAO2 92%Vitals: P 110, RR 33, BP 110/56 SAO2 92% +2 pedal edema+2 pedal edema Bilateral basilar crackles, SOB on minimal Bilateral basilar crackles, SOB on minimal

exertionexertion

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Scenario con’tScenario con’t

Weight gain of 2 lbs over past 5 daysWeight gain of 2 lbs over past 5 days Urine output =240 ml/8 hr shiftUrine output =240 ml/8 hr shift