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13 Cards in this Set
- Front
- Back
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY • ELECTRICAL CONDUCTION -4 |
– Sino-atrial node - pacemaker
– Atrio-ventricular node - regulator – Bundle of His – Purkinje fibers |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY CONTRACTION PHYSIOLOGY |
• ELECTRICAL CURRENT
• CALCIUM RELEASED TO SARCOPLASM • INERACTS WITH TROPONIN • ACTIN-MYOSIN COUPLING • CONTRACTION |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY ACTION POTENTIAL # of phases? what occurs at each phase? |
• PHASE 0 - Fast sodium Channel
• PHASE 1 - Mild repolarization • PHASE 2 - Slow calcium channel • PHASE 3 - Repolarization (potassium enters cell) • PHASE 4 - Resting (sodium/potassium pump) |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY FRANK-STARLING CURVE -3 |
• CARDIAC OUTPUT (heart rate times stroke volume) graphed versus left ventricular end diastolic pressure
• Cardiac Output increases with pressure up to a point of congestive heart failure. • Cardiac glycosides shift the curve of the graph |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY LOW OUTPUT FAILURE • Congestive Heart Failure • Treatment-4 |
– Diet - weight loss/low sodium/low fat
– Diuretics – Cardiac Glycosides – ACE inhibitors |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY CARDIAC GLYCOSIDE PHARMACOLOGY • INCREASED CONTRACTILITY OF HEART |
– Increased inotropic effect
– Cannot pump calcium out of cardiac cell – Leads to greater contractility and duration |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY • DECREASED A-V NODE CONDUCTION |
– Decreased chronotropic effect
– Used in atrial fibrillation |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY THERAPEUTIC MONITORING |
• Apical Pulse
– Hold dose for <60 • Serum drug level – Narrow therapeutic index • Serum potassium- caution in hypokalemia • Serum Calcium- caution in hypercalcemia • EKG |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY PHARMACOKINETICS 4 |
• Five half lives leads to steady state
• Loading Doses required • Toxicities - reversed by digoxin immune fab (Digibind®) • HALF LIFE – DIGOXIN - 24 HOURS – DIGITOXIN - 5 days |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY BIOAVAILABILITY 3 |
• INTRAVENOUS - 100%
• INTRAMUSCULAR - 80% • TABLET - 70% |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY TOXICITIES 5 |
• A-V BLOCK
• SINUS BRADYCARDIA • ARRHYTHMIAS • YELLOW-GREEN HALO VISION • CNS: Headache, weakness, anorexia |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY TOXICITY THERAPY 4 |
• Discontinue Cardiac Glycoside
• Digoxin immune fab (Digibind®) • Correct hypokalemia • Antiarrhythmic Agents |
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CARDIAC GLYCOSIDES
CARDIAC PHYSIOLOGY THERAPEUTIC USES |
• CONGESTIVE HEART FAILURE
• ADJUNCT THERAPY FOR ATRIAL FIBRILLATION |
