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The left anterior descending artery supplies the ____ ____ .
Intraventricular septum
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Ischemia involving the L anterior descending artery can be seen in what EKG leads?
- 1, AVL, V1-V6
- V2 – V4
- V1 – V3
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Probs w/the left anterior descending artery cause infarct in what part of the heart?
- L ventricle, anterior wall
- Anterior apical
- Anteroseptal
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Probs w/ the L anterior descending artery cause what 3 hemodynamic consequences?
- Typically HYPERDYNAMIC
- Papillary muscle rupture
- Pump failure
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What dysrhythmias are common to the L anterior descending artery?
- 2nd degree Mobitz 2 or 3rd degree blocks
- Sinus Tach
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The L circumflex artery supplies what parts of the heart?
- L atrium & ventricle
- 40-50% of the SA Node
- 8-10 % of the AV Node
- Bundle of his
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Infarct locations related to the L circumflex artery are what?
- Lateral wall, L ventricle
- Posterolateral
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Issues w/ the L circumflex show up in what leads?
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The hemodynamic consequences of a problem w/the L circumflex are what?
Typically NORMODYNAMIC
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What common dysrhythmia can be related to the L circumflex?
Sinus dysrhythmia
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The R coronary artery supplies what parts of the heart?
- R atrium & ventricle
- Posterior L ventricle
- 50-60% of the SA node
- Bundle of His
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Infarct locations related to the R coronary artery are what?
- Inferior Wall
- Posterior Wall
- R ventricle
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Ischemia related to the R coronary artery can be seen in what EKG leads?
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Hemodynamic consequences related to the R coronary artery include. . . .
- Typically HYPODYNAMIC
- Vasovagal response
- Hypotension
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Some unique findings that show w/a prob w/ the R coronary artery are what?
- Nausea/vomiting
- Can present w/isolated R failure
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Common dysrhythmias caused by a prob w/R coronary artery are what?
- 1st degree or 2nd degree mobitz I blocks
- Sinus Brady
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Hemiblock is short for ____ ____ & occurs when?
- Left Hemiblock
- When 1 or more fascicles of the LBB is/are blocked
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Hemiblocks increase the risk for complete heart block under what 2 circumstances?
- When combined w/1st or 2nd degree block
- 2 hemiblocks aka bifasicular
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Leads V1-V6 are know as ____ leads & view the chest in a ____ ____.
- Precordial leads
- Transverse plane
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Posterior precordial leads (V8,V9) are located where?
- V8 = 5th IC space Mid scapular
- V9 = 5th IC between V8 & spine
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A TCA OD presents how & in what lead?
Wide QRS in AVR
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What are the 6 rules for interpreting a 12 lead?
- Identify underlying rhythm
- Determine the axis
- Locate & ID ectopic beats
- Eval clinical & EKG evidence for cardiac ischemia &/or infarct
- Localize cardiac ischemia/infarct
- Look for BBB, Hemiblocks, Hypertrophy
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What does the axis of the heart indicate?
Predominant flow of electricity thru the heart
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Give 6 causes of left axis deviation. . .
- Mechanical shift of the heart
- LBBB
- WPW syndrome
- Emphysema
- Hyperkalemia
- Ventricular Ectopy
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Give 6 causes of right axis deviation. . . .
- Mechanical Shift of the heart
- Right ventricular hypertrophy
- RBBB
- Dextrocardia
- WPW syndrome
- Ventricular Ectopy
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A normal axis is between ____ & ____.
0 & +90
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A left shoulder axis is between ____ & ____.
0 & -90
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A right shoulder axis is between ____ & ____.
+ - 180 & -90
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A right axis is between ____ & ____.
+90 & + - 180
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A normal axis presents in Leads I, II, III as what?
- Lead I = up
- Lead II = up
- Lead III = up
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A physiologic L axis presents how in Leads I, II, III?
- I = up
- II= up/ even up & down
- III = down
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Pathological L axis presents what in Leads I, II, III & shows an ____ ____.
- I = up
- II = down
- III = down
- Anterior Hemiblock
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An R axis presents how in Leads I, II, III & shows a ____ ____.
- I = down
- II = up/ even up & down
- III = up
- Posterior Hemiblock
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An extreme R axis (aka ___ ___ ___) presents how in Leads I, II, III & is often __ __ __.
- I = down
- II= down
- III = down
- Ventricular in Origin
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How does a hemi block present anteriorly?
- QRS is normal or RBBB
- L axis deviation
- Sm qR wave in Lead I
- rS wave in lead III
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What are the clinical correlates of an anterior hemiblock?
- Anterior & inferior MI
- Lowest Mortality
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A posterior hemiblock presents with?
- QRS normal or RBBB
- R axis deviation
- Sm qR wave in lead III
- Lg rS wave in lead I
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What are the clinical correlates of a posterior hemiblock?
- Has dual blood supply so requires extensive cardiac damage to injure
- 71% mortality
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What exactly is a hemiblock?
Block of 1 of the fascicles of the LBB
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What is a bifasicular block?
Block where 2 fascicles are occluded; RBBB & anterior (most common) OR posterior hemiblock
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Until proven otherwise all axis deviations are assumed to represent a ____ so ____ ____ are contraindicated if the pt has what or what.
- Hemiblock
- Class I Antidysrhythmic
- Anykind of AV block or BBB
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What are some problems (5) w/pts w/a bifasicular block?
- Much sicker than an uncomplicated MI
- May drop BP precipitously
- May go into V Fib or tach w/o warning
- May go into complete heart block
- Should not receive Class I antidysrhythmics
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Describe a trifasicular block.
A bifasicular block plus a 1st degree block
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What 3 things can cause damage to the bundles/
- Myocardial infarction or ischemia
- Congenital disorders
- Post RF ablation
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Anterior/posterior myocardial infarction/ischemia cause bundle damage where?
- Anterior MI RBBB
- Posterior MI LBBB
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The ___ ___ ___ conducts across the rt ventricle.
Right bundle branch
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The Left bundle branch is divided in to what 3 parts & conducts across where?
- Anterior, posterior & septal (minor)
- Across the left ventricle
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What happens in a bundle branch block?
Branches of the bundle of his become damaged
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What could happen to conduction thru an area w/a BBB?
It could be slowed, partially blocked or completely blocked
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What are the hallmarks of a bundle branch block?
- QRS > 0.12 (widest in leads closest to block)
- Abnormal QRS morphology
- T polarity opposite of QRS
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How do we recognize BBB’s?
- QRS >0.12 in V1
- Circle J point
- Draw line back into complex then up or down w/terminal deflection
- Shade in triangle made by line
- Arrow up = R turn signal = RBBB
- Arrow down = L turn signal = LBBB
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What are the 6 steps in a V Tach algorithm?
- ERAD + Pos V1 OR
- QRS morphology in V1 or V6 OR
- RAD + Neg V1 OR
- Concordance OR
- RS interval (V lead) is > 100ms OR
- QRS > 0.14 sec
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What is the effect of cardiac ischemia on the Q waves?
it creates a deep wide Q wave that is a permanent sign of the event
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An ST segment elevation is indicative of what?
- Epicardial injury
- May be associated w/ peaked T waves in acute state
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Abnormal T waves are ____, ____ & ____.
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What is seen in deep T wave inversion?
- Seen in leads reflecting ischemia
- ST segment preceding T Waves is commonly coved upward
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Septal infarcts involve ___ ___ ___ & show where on the EKG?
- Left Anterior Descending
- Leads V1 & V2
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An infarct localized in an Anterior Wall involves the ___ ___ ___ artery and shows on leads ___ & ___.
- Left Anterior descending
- V3 & V4
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A lateral wall infarct shows in what arteries & what leads?
- Left Anterior Descending &/or Left Circumflex
- 1, V5, V6
- AVL = High Lateral Wall
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Anterolateral wall infarct involves what 2 arteries & shows in what leads?
- Left Anterior Descending & Left Circumflex
- 1, aVL, V3-V6
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An inferior wall infarct affects what arteries & shows in what leads?
- Rt coronary or Left Circumflex
- 2, 3 & aVF
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A posterior wall infarct involves what arteries & shows how on EKG?
- Distal Left block or posterolateral branch
- Leads V1 - V4
- ST depression
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