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12 Cards in this Set
- Front
- Back
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Positive inotropic drugs |
Increases force of myocardial contraction. |
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Positive chronotropic drug |
Increases rate of heart beat |
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Positive dromotropic drug |
Excelerates conduction. |
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Heart Failure and Dysrhythmias |
Typical client presentation: (poor perfusion) - decr. urinary output - Edema -- lower extremities, ascites, hepatospleanomegaly - Dyspnea and respiratory crackles - 2nd to pulm. edema - Fatigue -- can't meet metabolic needs - Paroxysmal nocturnal dyspnea - Poor peripheral pulses, skin colour, and temp.
Normal ejection fraction = 65% - when this worsens we see clients become symptomatic |
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Causes of Heart Failure |
Myocardial deficiency: - Inadequate contractility -- MI, 2nd to cardiomyopathy, infection, CAD - Inadequate filling -- atrial fibrillation, infection, ischemia, cardiac tamponade
Incr. Myocardial Workload: - Pressure overload -- hypertension, outflow obstruction - Volume overload -- congenital abnormalities (septal defect), hypervolemia |
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Caridac Glycosides: |
- Old and effective therapy for HF - From the digitalis plant called foxglove - Digoxin (Lanoxin) is the most frequently prescribed cardiac glycoside and only one available in Canada, therefore is the prototype. - Digitalization: with use of digoxin critically ill pt.'s can be restored to near normal states within hours after initiating treatment. - DIG trial results: low digoxin levels = decr. mortality rates, whereas higher doses = incr. mortality |
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Mechanism of Action: Cardiac Glycoside (Digoxin) |
- Primary beneficial effect is an increase in myocardial contractility: inhibits sodium-potasium APTase pump = incr. cellular sodium which causes incr. in Ca++ = incr. myocardial contraction.
- Augments vagal tone = incr. diastolic filling- allows heart muscle to relax and fill, causing more blood going out, less staying in.
- Changes the electrical conduction properties of the heart: reduce rate (velocity) of electrical conduction from SA to AV node, and causes prolonged depolorization. |
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Numerous Drug effects of Digoxin |
- Positive inotropic -- incr. force & velocity - Negative chronotropic -- decr. HR - Negative Dromotropic -- decr. automaticity of SA node - Incr. Stroke vol. - Decr. heart size during diastole - Decr. venous BP - Incr. coronary circulation - incr. diuresis (b/c incr. renal perfusion) - Palliation of exertiona; and PND, cough, cyanosis |
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Indications of Digoxin |
- Heart Failure - Supraventrical dysrhythmias: atrial fibrillation and atrial flutter |
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Contraindications or Digoxin |
- Known drug allergy - 2nd and 3rd degree heart block -- bradycardiac dysrhythmia - Ventricular tachycardia or fibrillation - Heart failure resulting from diastolic dysfunction - Subaortic stenosis -- obstruction in left ventricle below the aortic valve - atrial fibrillation (also an indication, so it is a clinical judgment call) |
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Adverse Effects of Digoxin: |
Comments: - side effects can be serious - Digoxin has narrow therapeutic window (1-2.5nmol/L) - monitoring digoxin levels after the drug has reached steady state is only required if there are issues with toxicity, non-adherence, or deteriorating kidney function - Low potassium levels or poor renal function can increase risk for toxicity -- i.e. electrolytes must be monitored.
Cardiovascular: - Dysrhthmias, includes bradycardia (most common) or tachycardia CNS: - Headaches, fatigue (decr. HR), malaise, confusion (decr. perfusion to brain), convulsions Eye: - Colored vision (seeing green, yellow, purple), halo vision, flickering lights -- thess are classic S&S GI: - Anorexia, nausea, vomiting, diarrhea |
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Toxicity and Management of Overdose: Digoxin |
- Easy to overdose kids - |
