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pnm- pharm > WEEK 6- Positive Inotropic Agents: > Flashcards

WEEK 6- Positive Inotropic Agents: Flashcards

1
Q

Positive Inotropic Agents

A 
Drugs that increase the force of myocardial contraction
Used to treat heart muscle failure
Cardiac glycosides
-Digoxin
-Phosphodiesterase inhibitors
-Amrinone and Milrinone
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2
Q

left-ventricular-end-diastolic volume

A

More blood accumulates in the ventricles as a result of incoming blood plus that which was not effectively ejected from the previous contraction

This leads to pressure build up in the blood vessels leading to the heart which eventually leads to further build up (ie like a chain reaction)

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3
Q

L VS R SIDED FAILURE

A

Left ventricular failure—elevated left ventricular pressure produces pulmonary edema (pulmonary congestion) resulting in cough, SOB & air hunger
LUNGS=LEFT

Right ventricular failure—elevated right ventricular pressure leads to venous congestion & peripheral edema i.e. edema of the ankles, jugular venous distention, ascites (abd distention) & hepatic congestion

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4
Q

SA node: pacemaker of the heart

A

HR 60-100

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5
Q

AV node: controls the rate of impulses arriving to the ventricles

A

HR 40-60

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6
Q

Inotropic

A

increase the Force of myocardial contraction. this is what dig.
INCREASE CONTRACTILITY

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7
Q

Chronotropic

A

Heart rate in the only med crash cart if they are bradycardic and dilates

MED:ATROPINE

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8
Q

Dromotropic

A

Speed of conduction of electrical impulses through the SA (sinoatrial) & AV (atrioventricle)nodes

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9
Q

Cardiac Drugs Work By:

A

Increasing the force of contraction referred to as “positive inotropic drugs”

Increasing the heart rate referred to as “positive chronotropic drugs”

Increasing conduction of electrical impulses through the SA (sinoatrial) & AV (atrioventricle) nodes referred to as “positive dromotropic drugs”

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10
Q

Cardiac Glycosides: Digoxin

need to know

A

Used in heart failure and to control ventricular response to atrial fibrillation or atrial flutter

Referred to as positive inotropic agents

Loading dose of digoxin is necessary to establish a therapeutic blood level and to prevent toxicity
Digitilization

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11
Q

Cardiac Glycosides:Mechanism of Action

A

Increase myocardial contractility

Enhances the vagal tone therefore resulting in elevated diastolic filling time

Change electrical conduction properties of the heart
Decrease rate (velocity) of electrical conduction
Prolong the refractory period between the SA node and AV node

Digoxin and Digitalis

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12
Q

Positive inotropic effect FOR CARDIAC GLYCOSIDES DRUG EFFECTS

A

Increase in force and velocity (rate) of myocardial contraction (without an increase in oxygen consumption)

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13
Q

Negative chronotropic effect FOR CARDIAC GLYCOSIDES DRUG EFFECTS

A

Reduced heart rate

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14
Q

Negative dromotropic effect FOR CARDIAC GLYCOSIDES DRUG EFFECTS

A

Decreases automaticity at SA node; decreases AV nodal conduction (controls conduction of electrical impulses)

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15
Q

Cardiac Glycosides:Drug Effects

A

Increased stroke volume
Reduction in heart size during diastole
Decrease in venous BP and vein engorgement
Increase in coronary circulation
Promotes diuresis due to improved blood circulation
Reduce pressure and back up of fluids in the lungs

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16
Q

Cardiac Glycosides:Indications

A

Heart failure
Supraventricular dysrhythmias
->Atrial fibrillation and atrial flutter

17
Q

Digoxin (Lanoxin)

A

Very V. V. narrow therapeutic window
– Drug levels must be monitored to prevent toxicity
Normal lab values 0.5 to 2mmol/l -NORMAL DIG LVLS
PROB Q6

– Low potassium (HYPOKALEMIA) levels increase its toxicity

18
Q

Digoxin: Side/Adverse Effects

A

Cardiovascular
Dysrhythmias, including bradycardia and hypotension

CNS
Headaches, fatigue

Eye
**Colored vision (seeing green, yellow, purple), halo vision, flickering lights (sign of toxicity)

GI
Nausea, vomiting, diarrhea

19
Q

Digoxin ToxicityAntidote

A

Digoxin Immune Fab (Digibind) therapy is indicated for:

Hyperkalemia (serum potassium >5 mmol/L) in a digitalis-toxic patient

Life-threatening cardiac dysrhythmias

Life-threatening digoxin or digitoxin overdose which leads to severe bradycardia, hypotension, heart block
Normal lab values 0.5 to 2mmol/l

20
Q

Phosphodiesterase Inhibitors

A

Work by inhibiting the enzyme phosphodiesterase (thereby allowing more calcium to the heart muscles)

Results in:
Positive inotropic response (^ contraction)
Vasodilation (positive lusitropic effects)
Decreases work load, better perfusion to heart due to relaxed blood vessels

Two agents
Amrinone and Milrinone

21
Q

Phosphodiesterase Inhibitors:Indications

A

Short-term management of heart failure

Given when patient has not responded to treatment with digoxin, diuretics, and/or vasodilators

Often given as weekly 6-hour infusions for:

  • Improved quality of life
  • Mainly for congestive heart failure
  • Decreased readmissions for heart failure episodes
  • For end stage heart failure
22
Q

Phosphodiesterase Inhibitors:Side/Adverse Effects

A

Amrinone
Thrombocytopenia, most worrisome
Dysrhythmia, nausea, hypotension

Milrinone
Dysrhythmia, mainly ventricular
Hypotension, angina, hypokalemia

23
Q

Thrombocytopenia

A

is a condition in which you have a low blood platelet count. Platelets (thrombocytes) are colorless blood cells that help blood clot. Platelets stop bleeding by clumping and forming plugs in blood vessel injuries.

24
Q

Positive Inotropic Agents:Nursing Implications

A

Assessment of VS

BP
ALWAYS DO Apical pulse for 1 full minute (especially when pt is on Digoxin)
Hold Digoxin dose if apical pulse is 120BPM
Heart sounds, breath sounds HEAVY BREATHING (COULD BE DEVELOPING LEFT HEART FAILURE

Weight, I&O measures
ECG
Serum labs: potassium (hypokalemia can lead to Digoxin toxicity), sodium, magnesium, calcium, renal and liver function studies

25
Q

signs/symptoms of toxicity

A 
Anorexia, nausea, vomiting, diarrhea
Visual disturbances (blurred vision, seeing green or yellow halos around objects – mainly seen with Digoxin toxicity)
26
Q

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

A

Decreases absorption

27
Q

PPL WHO ARE ON DIGITLALIS

A

ARE AROUND 3RD OR 4TH DEGREE HEART FAILURE

pnm- pharm (19 decks)

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