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42 Cards in this Set
- Front
- Back
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• What is atrial fibrillation?
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Diffuse chaotic electrical activity in the atria with deterioration of mechanical function
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• What is the pathophysiology of atrial fibrillation?
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• How common is atrial fibrillation?
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o Affects 5-10% of patients 75 years and older
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Describe the general classification of atrial fibrillation.
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Atrial fibrillation is broadly classified as either new ("first detected/diagnosed") or recurrent.
New atrial fibrillation is AF that has not been previously diagnosed, independent of the duration of AF or the presence or absence of symptoms. AF is considered recurrent once two or more episodes have occurred. |
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What are the three types of recurrent atrial fibrillation?
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Paroxysmal
Persistent Permanent |
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What is paroxysmal atrial fibrillation?
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Recurrent AF (≥2 episodes) that terminates spontaneously in less than seven days, usually less than 24 hours.
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What is permanent atrial fibrillation?
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AF that lasts for more than one year and cardioversion either has not been attempted or has failed
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What is persistent atrial fibrillation?
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AF that fails to self-terminate within seven days, with episodes often requiring pharmacologic or electrical cardioversion to restore sinus rhythm.
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Do patients with persistent atrial fibrillation progress to permanent atrial fibrillation?
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While a patient who has had persistent AF can have later episodes of paroxysmal AF, AF is generally considered a progressive disease.
In individuals with paroxysmal AF, progression to persistent and permanent AF occur in >50 percent beyond 10 years despite antiarrhythmic therapy. |
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• What are the principle pathophysiologic sequelae of atrial fibrillation?
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o Reduction in cardiac output: hypotension, pulmonary edema (i.e. heart failure)
o Increase in myocardial oxygen demand due to tachycardia: myocardial ischemia o Atrial thrombus formation: stroke |
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• What are the two most common causes of atrial fibrillation in North America?
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o Systemic hypertension and coronary artery atherosclerosis
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• Name 8 causes of atrial fibrillation.
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Divide the causes of atrial fibrillation into local and systemic.
5 local causes: ISCHEMIC HEART DISEASE (coronary artery atherosclerosis) Valvular disease Pericarditis Post-surgical stress Stress from a pulmonary embolism 3 systemic causes: HYPERTENSION Hyperthyroidism Fluid/electrolyte disturbances |
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Clinical Presentation
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• What is the ECG finding associated with atrial fibrillation?
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o Irregularly irregular rhythm
o Absence of discrete P waves |
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• How fast is the atrial rate in atrial fibrillation?
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What are the potential signs and symptoms of atrial fibrillation?
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Arrhythmia:
Palpitations/chest discomfort Heart failure: Dyspnea, hypotension, light-headedness/syncope Thrombosis: Symptoms of stroke/TIA |
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• How fast is the ventricular rate in atrial fibrillation?
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What minimal investigations would you order to investigate suspected or confirmed atrial fibrillation?
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Laboratory investigations:
CBC, electrolytes, TSH, CK/troponin Imaging: EKG, TTE, chest X-ray |
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Short-Term Management
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What are the three principles goals in short-term management of atrial fibrillation.
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1) Rate control
2) Anticoagulation prophylaxis 3) Cardioversion |
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In which patients presenting with acute AF are rate-control measures indicated?
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Any patient with a rapid ventricular rate should be rate-controlled
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How do you rate-control a patient with acute AF?
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Beta-blocker or calcium-channel blocker
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In which patients presenting with acute AF is anticoagulation prophylaxis indicated?
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Patients that have been symptomatic for greater than 48 hours
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In which patients presenting with acute AF is cardioversion indicated?
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Patients who are hemodynamically unstable
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What are the two forms of cardioversion?
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Electrical cardioversion and pharmacologic cardioversion
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What must you consider before cardioverting a patient?
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Cardioverting a patient back to sinus rhythm in the presence of an atrial thrombus may result in clot embolization leading to a cerebral infarct.
Patients who have been symptomatic for >48 hours or of unknown duration are considered high risk. Two approaches: pre-conversion TEE or pre-conversion anticoagulation, both followed by 4 weeks of anticoagulation prophylaxis. Option 1: Patients may undergo TEE before cardioversion followed by 4 weeks of anticoagulation prophylaxis post-conversion. Option 2: Patient may be anticoagulated for a period of 3 weeks before cardioversion followed by 4 weeks of anticoagulation prophylaxis post-conversion. |
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Which drug/drugs is/are used to pharmacologically convert a patient in AF?
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Class III antiarrhythmics (e.g. amiodarone, ibutalide)
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Long-Term management of AF
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What are the two primary objectives in the long-term management of AF?
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Rate/rhythm control and anticoagulation prophylaxis
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What agents are used to achieve long-term rate control?
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Beta blocker, non-DHP calcium channel blockers (e.g. diltiazem), digoxin as an adjunct
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What is the definition of a controlled heart rate?
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Rate <110 well resting
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In which patients is a rhythm-control strategy indicated in the long-term management of AF?
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Symptomatic patients
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Name two agents used for rhythm-control in the long-term management of AF.
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Amiodarone, sotalol
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How do you decide what type of anticoagulation prophylaxis, if any, a patient should receive in the long-term management of atrial fibrillation?
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Determine their risk for stroke/TIA
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How do you determine a patient with AF’s risk for stroke/TIA?
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CHADS2 score
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Describe the CHADS2 risk stratification scheme.
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C Congestive heart failure (1 point)
H Hypertension (1 point) A Age over 75 (1 point) D Diabetes Mellitus (1 point) S2 Prior stroke/TIA (2 points) |
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• What is the mechanism of action of warfarin?
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o Warfarin inhibits an enzyme responsible for activating vitamin K. As a result, it has the effect of inhibiting vitamin K.
o Vitamin K is responsible for the synthesis of clotting factors II, VII, IX, X (1972) as well as the fibrinolytic molecules proteins C and S. o Warfarin, therefore, has the effect of reducing the amount of factors X, IV, VII, and II, as well as proteins C and S. |
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What type of anticoagulation prophylaxis should a patient with a CHADS score of 0 be on?
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None or consider aspirin
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What type of anticoagulation prophylaxis should a patient with a CHADS score of 1 be on?
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ASA
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What type of anticoagulation prophylaxis should a patient with a CHADS score of 2 be on?
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Warfarin
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What type of anticoagulation prophylaxis should a patient with a CHADS score of 3 or higher be on?
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Warfarin
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What is the therapeutic INR range for warfarin?
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2.0-3.0
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