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Cardiac Glycosides naturally occur in plants like Digitalis. What is the action of Cardiac Glycosides?
Inhibit the Na+/K+ pump, resulting in an ^in intracellular Na+. This ^ leads to an influx of calcium, causing the cardiac muscle fibers to contract more efficiently.
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Digitalis preparations have 3 effects on the heart muscle, what are they?
- +inotropic action
- -chronotropic action
- -dromotropic action
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Explain what a +inotropic action is.
+inotropic action ^myocardial contraction stroke volume.
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Explain what -chronotropic action is.
-chronotropic action <HR
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Explain what -dromotropic action is.
-dromotropic action <conduction of the heart cells.
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How do the 3 effects of Digitalis effect not only the heart, but the rest of the body too? (+inotropic, -chronotropic, -dromotropic)
The ^in myocardial contractility of the +inotropic effect strengthens cardiac, peripheral, & kidney fxn by enhancing cardiac output, <preload, improving blood flow to the periphery & kidneys, <edema, & promoting fluid excretion. as a result fluid in the lung & extremities is <.
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What do +Inotropic drugs do & what are they used to treat?
- ^the force of myocardial contraction
- Tx heart muscle failure
- *cardiac glycosides: digoxin
- *Phosphodiesterase inhibitors
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Explain what Heart Failure is.
The heart is unable to pump blood in sufficient amounts from the ventricles to meet the body's metabolic needs.
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With Heart Failure the symptoms vary depending on the affected cardiac area. What types of s/s are noted with Left ventricular & Right ventricular failure?
- Left ventricular failure: pulmonary s/s
- Right ventricular failure: systemic s/s
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What are the possible causes of Heart Failure?
- Cardiac defect: Myocardial infarction or valve deficiency.
- Defect outside of heart: coronary artery disease, pulmonary HTN, & diabetes
- Supraventricular dysrhythmias: Atrial fib, Atrial flutter
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How many stages of Heart Failure are there?
- 4 stages
- 1-4, 4th stage being the worst.
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Cardiac Glycosides (digitalis) were originally obtained from what plant? & what drug is the prototype of Digitalis?
- Digitalis is originally from the Foxglove plant.
- **Digoxin is the prototype
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What is the mechanism of action for the Cardiac Glycoside, Digoxin (Lanoxin)?
- ^myocardial contractility
- change electrical conduction properties of the heart.
- result: <HR & improve cardiac efficiency -> "slows & strengthens the heart"
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What are the A/E of Digoxin?
- Cardiovascular: Dysrhythmias, bradycardia or tachy.
- CNS: HA, fatigue, malaise, confusion, convulsions.
- Eyes: Colored vision (green, yellow, purple), halo vision, flickering lights.
- GI: Anorexia, N/V/D
- ***if vomit, NEVER give Dig after!! CALL MD.
- **dig level NEEDED
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The cardiac glycoside, Digoxin (lanoxin) has a VERY narrow therapeutic window. What things can effect this window?
- <K+ levels ^Dig toxicity
- Predisposing conditions: Hypokalemia, Hypercalcemia, dysrhythmias, advanced age.
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What drug is used for life threatening Bradycardia, Advanced heart block or Dysrhythmias caused by Digoxin toxicity?
Digibind (digoxin immune fab therapy)
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What are the critical nursing assessments for Cardiac Glycosides like Digoxin?
- Apical pulse 1 whole minute
- Check Dig levels
- if AP <60 or >120b/min HOLD & call MD
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What are the nursing implications for Cardiac Glycosides like Digoxin?
- Hold dose & call MD if pt has s/s of toxicity
- Pts should report ASAP Wt gain of 2lbs or more in 1day or 5lbs or more in 1week
- Infants & children need BID dosing
- *NEEDS to be given 12hrs apart.
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Name some Inotropic drugs used to treat Acute Heart Failure.
- Cardiac Glycosides: Digoxin
- Phosphodiesterase Inhibitors: Inocor & Primacor
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How does the Inotropic drug class, Phosphodiesterase Inhibitors work?
by inhibiting the enzyme phosphodiesterase, promoting a positive inotropic response & vasodilation.
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The Inotropic drugs Inocor & Primacor (phosphodiesterase Inhibitors) work by doing what?
^stroke volume & cardiac output & promote vasodilation.
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What are the A/E related to the phosophodiesterase inhibitor, Inocor & Primacor?
- Inocor: Thrombocytopenia
- Nausea
- <BP
- Angina
- ^liver enzymes w/long-term use
- Primacor: Dysrhythmia
- <BP
- Angina
- Hypokalemia
- Tremor
- Thrombocytopenia
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What are the nursing considerations with the Phosphodiesterase inhibitors, Inocor & Primacor?
- *short-term managment of HF
- *Given when pt has NOT responded to Tx w/Digoxin, diuretics &/or vasodilators.
- *Given IV for NO longer than 48-72hrs
- *Monitor EKG & cardiac status
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What are the nursing Implications with Inotropic drugs?
- Monitor for therapeutic effects
- Are s/s of HF resolving???-^urinary output
- -<edema, SOB, dyspnea, crackles, fatigue
- -resolving of paroxysmal nocturnal dyspnea
- -improved PP, skin color, temp
- Monitor for A/E
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Name some of the other agents used to Tx HF beside the +inotropic drugs.
- Vasodilators: <venous return to heart
- Angiotensin-converting enzyme (ACE) Inhibitors: dilate venules & arterioles, improving renal blood flow & <blood fluid volume.
- Angiotensin II receptor blockers (ARBs)
- Diuretics: thiazides, lasix & spirolactone: reduce fluid & blood volume.
- Certain beta-blockers: carvedilol & metoprolol
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