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37 Cards in this Set
- Front
- Back
Normal heart rhythm
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SA node -> atrial muscle -> AV node -> ventricles
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Tachyarrhythmia
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If firing is too rapid
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Arrhythmia
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- An altered impulse pathway
=> altered pacemaker or ectopic focus => alteration in normal pathway |
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What is the major cause of sudden cardiac death?
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Ventricular arrhythmias
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Normal resting heart cells contain more __, __, and __ on the outside of the cell and more __ on the inside
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Na+, Ca2+, Cl-; K+
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Calcium influx relates to __ and potassium efflux relates to ___.
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Contraction; relaxation
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Tx of arrhythmias
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- No Tx is often the best course of action, especially when it's not life threatening
- Any anti-arrhythmia drug can cause an arrhythmia |
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Non-drug Tx options to arrhythmias
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Cardiac pacemakers, cardioversia, surgical removal of damaged heart muscles
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Antiarrhythmia drugs affect what?
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Abnormal foci
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Class I drugs- Local Anesthetics
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Inhibit Na+ influx into cell
Ia- Quinidine, Procainamide, Dispyramide Ib- Lidocaine, Mexitilene |
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Procainamide
(Class Ia) |
- Lupus-like symptoms in slow acetylators
- Doesn't enter the CNS - Given orally - Inhibits Na+ influx |
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Quinidine
(Class Ia) |
- Given orally
- All arrhythmias - Depresses all muscle function - Anticholinergic effects=> inc HR - Inhibits Na+ influx - S.E: nausea, vomiting, anorexia, gets into CNS, tinnitus and altered color vision |
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Dispyraminde
(Class Ia) |
- Strong anti-vagal effects
- For ventricular arrhythmias - Opposite of DUMBBEL effects - Inhibits Na+ influx |
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Lidocaine
(Class Ib) |
- DOC in emergency situations for ventricular arrhythmias
- Given IV - Low toxicity - Gets into CNS (tremors, slurred speech, seizures) - Inhibits Na+ influx |
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Mexitilene
(Class Ib) |
- Lidocaine analog
- Can be given orally - Inhibits Na+ influx |
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Class II Drugs (overview)
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- Beta blockers
- Prevents Epi and NE from reaching the heart - Tx of arrhythmias due to excess sympathetic stimulation - DOC for atrial fibrillation |
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Class II Drugs (3)
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1) Propranolol: decreases pacemaker firing rate, dec HT; contraindicated in patients w/ lung problems
2) Metoprolol: more specific for beta 1 3) Esmolol: even more specific and faster onset |
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Class III Drugs (3)
K+ Channel Blockers |
- For atrial fibrillation
1) Sotalol: blocks beta receptors too 2) Amiodarone: works on all four pathways; fatal pulmonary fibrosis, liver damage, corneal and skin deposits, optic neuritis, blue-gray skin coloring, alters thyroxine production 3) Dronedarone: Like the above but no iodine |
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Class IV Drugs
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- Ca2+ channel blockers
- Vasodilators- dec BP - Useful for atrial tachycardia but not ventricular arrhythmias |
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Adenosine
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- DOC for paroxysmal ventricular tachycardia
- Given by IV - T.5 is 10 seconds |
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Angina
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- Not enough blood flow to heart muscle
- Chest pains: may be atherosclerotic plaques in coronary artery; pain upon exercise or pain at rest (unstable angina) |
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Prinzmetal Angina
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Spasms of coronaries
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Drugs that Tx angina act to do what?
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Increase blood flow to the heart
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The Nitrates
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Nitroglycerin (GTN)
- Will dec pain in 2 min - Cause rapid dilation in all BVs - Given sublingually- due to first pass effect Mechanism of action: release of NO => inc cGMP=> dilation |
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Isosorbide dinitrate
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- Longer lasting nitrate
- Can be given orally |
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Side effects of nitrates (3)
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Orthostatic hypotension, flushing, headache
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T/F Tolerance doesn't develop with nitrate use
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False, tolerance develops rapidly (tachyphylaxis)
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Other drugs that can Tx angina
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Anything that can decrease heart work (beta 1 blockers, calcium channel blockers)
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Congestive heart failure
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- Heart can't pump enough blood to the body
- Blood gets to heart but isn't pumped rapidly enough so heart becomes enlarged => blood backs up into the lungs (pulmonary congestion) => edema of lungs => can't breathe => kidney under perfused => retains sodium and water => full body edema |
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Causes of CHF
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MI, heart valve problems
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How the heart adapts to failure
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Early stages => dec CO, dec effective blood volume
1- Inc release of Epi, NE, angiotensin II => inc BP, in HR 2- Kidney in blood vol => angiotensin II => inc Na+ and H20 retention 3- Enlargement of the heart => inc force of contraction Finally... heart failure |
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Tx of cardiac insufficiency
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Ionotropic agents
- Increase force of heart contraction - Increase calcium in heart muscle - The cardiac glycosides: Digoxin |
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Mechanism of action of ionotropic agents
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- Inc force and rate of contraction
- Enzyme inhibitors (Na+/K+ ATPase pump): Na+ stays in cell, inhibits Ca2+ pumps => inc contractility - Increases vagal tone and anti-arrhythmic effects |
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Toxic effects and drug interactions of ionotropic agents
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- Cardio: arrhythmias
- CNS: vision (inc yellow/green tinting), hallucinations, inc nausea and vomiting - Effects of digoxin greatly increase when K+ is low because digoxin binds to K+ site of Na+K+ ATPase |
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Other Ionotrops
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Beta agonists: dobutamine, DA
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Best Tx for cardiac insufficiency
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Prevent the body from accommodating the failing heart which increase the life span of patients
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Agents that increase blood flow to selected organs (3)
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1- Sildenafil
2- Vardenafil 3- Tadalafil - These are Enzyme inhibitors: inhibit cGMP phosphodiesterase=> dilates arteries of the corpus cavernosum S.E: slight dec in BP, don't use w/ other vasodilators, visual disturbances, direct retinal damage Other uses: pulmonary hypertension |