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20 Cards in this Set
- Front
- Back
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Complete failure of conduction from atrium to ventricle.
Implies advanced AV conduction disease. The ventricles have to have an alternate or escape rhythm and are under a secondary pacemaker. A wide QRS escape rhythm implies a block in the distal His or bundle branches A narrow QRS implies block in the AV node or proximal His, narrow QRS rhythms are generally more stable than wide QRS rhythms |
3rd degree AV block
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What are the most likely causes of 3rd degree AV block?
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Coronary Artery Disease
Drug related |
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What does an echocardiogram test for when you have a suspected 3rd degree block?
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LV function
Pericardial effusion valvular heart disease |
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What symptoms point to the need of a pacemaker in this case of 3rd degree heart block?
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Class I:
3rd degree block with symptoms (dizziness) 3rd degree block with cardiomegaly or LV dysfunction |
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What type of pacemaker is indicated in 3rd degree AV block?
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rate-responsive dual-chamber pacemaker
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What effects this arrhythmia have on the pumping abilities of the Heart in 3rd degreee AV block?
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Loss of coordination between atria and ventricles decreases cardiac output
Atrial contraction contributes a big portion of filling in elderly |
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In athletes with sinus bradycardia, what abnormality can sometimes be seen on EKG?
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Junctional escape beat (happens when the rate slows during rest; the junction is not overdrive-suppressed)
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What conclusions were drawn from the long term endurance athlete study?
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Although the benefits of moderate regular exercise are undisputed, high intensity lifelong endurance exercise may be associated with altered cardiac structure and function.
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What are compensatory mechanisms in sinus bradycardia?
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Athletes can generate adequate stroke volume and cardiac output at rest as well as at exercise.
Although the resting hear rate is very slow they can increase the HR to very high levels without any abnormalities. In contrast patients with pathological bradycardias have chronotropic incompetence |
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What will you need to identify sick sinus syndrome?
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Holter monitor (will usually need a strip longer than 10 seconds to identify changes in rhythm)
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What factors predispose to sick sinus syndrome?
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Coronary artery disease
AV nodal blocking or slowing drugs Hypothyroidism |
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What is one of the most useful tests in diagnosing heart dysfunction?
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echocardiogram
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What is the purpose of an electrophysiology study?
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evaluates electrical activity of the heart (rarely needed)
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What is the treatment of sick sinus syndrome?
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“Primum non nocere”. "First, do no harm“.
Treat or eliminate any predisposing or reversible causes. Follow the ACC/AHA/HRS guidelines. Refer to a specialist |
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PR interval prolonged, no dropped QRS
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1st degree AV block
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progressive lengthening of PR interval until QRS complex drops, then cycle repeats
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Mobitz type 1 (2nd degree AV block type 1)
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consistently lengthened PR intervals (PR interval doesn't change) with dropped QRS complexes
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Mobitz type 2 (2nd degree AV block type 2)
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P wave and QRS complexes have regular rhythm but are independent of each other (dissociated)
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3rd degree AV block (complete block)
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What are the reversible causes of AV block?
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Beta Blockers
Ca channel blockers Acetylcholine (parasympathetic simulation) |
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What are treatments of AV block?
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treat reversible causes
pacemaker |
