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EKG > Lecture 6 (Intraventricular Conduction Defects) > Flashcards

Lecture 6 (Intraventricular Conduction Defects) Flashcards

1
Q

Right atrial enlargement cause

A

chronic pulmonary diseases may cause it in the response to the need for greater filling pressures in the right ventricles

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2
Q

Left atrial enlargement cause

A

mitral regurgitation due to blood being forced backwards into the left atria

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3
Q

leads to asses atrial enlargement

A

II and V1

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4
Q

RAE finding on EKG

A

increased amplitude of the first part of the p wave

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5
Q

LAE finding on EKG

A

increased NEGATIVE amplitude in the terminal portion of the p wave in V1 Increased duration or width of the P wave

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6
Q

Ventricular Hypertrophy Causes

A

caused by chronic poOrly treated HTN-bc there is more muscle to depolarize there is more electrical activity occuring in the hypertrophied muscle
-reflected by changes in amplitude of portions of the QRS complex

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7
Q

Ventricular Hypertrophy general EKG findings

A

V1 electrode normally positive-wave of depolarization moving through LV mmoving away from electrode
-mainly produces negative QRS complexes (short R with larger S waves)

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8
Q

RVH EKG findings

A
  • most common characteristic in limb leads is RAD

- in precordial leads R waves are more positiv which lie closer to lead V1

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9
Q

LVH EKG findings

A
  • increased R wave amplitude in precordial leads over LV (V5-V6)
  • S waves are smaller in leads over LV (V5-V6) but larger in leads over RV (leads V1-0V2)
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10
Q

Bundle Branches

A

Bundle of His divides into right and left bundle branches

-left bundle branch divides into SEPTAL, ANTERIOR, and POSTERIOR fascicles

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11
Q

Normal QRS complex

A

narrow

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12
Q

Bundle Branch Block definition

A
  • results in one or both bundle branches failing to conduct impulses
  • produces delay in depolarization of the ventricle it supplies
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13
Q

Bundle Branch Block EKG findings

A

QRS MUST BE >/=0.12s
FOR BBB-RR’ configuration with normal QRS interval is called an “INCOMPLETE BBB”-widened QRS complex-RR’ configuration in chest leads

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14
Q

RR’ configuration in chest leads

A
  • 2 peaks or rabbit ears

- the delayed ventricle is represented by R’

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15
Q

Possible sites of BBB

A
  • RBBB (right bundle branch block)
  • LBBB (left BBB)
  • LAHB/LAFB (left anterior hemiblock or fascicular block)
  • LPHB/LPFB(left posterior hemiblock or fascicular block
  • any combination of the above
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16
Q

RBBB Criteria

A 
Main ones:
-Prolonged QRS (complete has QRS >0.12s)
-M-shaped RR' in lead V1
-Wide S wave in Lead 1 and V6
Others:-LV depolarizes normally but RV is delayed, represented by R'
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17
Q

RBBB seen in

A

CAD, Pulmonary embolism

18
Q

Frontal plane QRS axis in RBBB

A

should be in normal range (0-+90)

19
Q

ST-T waves in RBBB

A

normal ST-T waves in RBBB should be oriented opposite to the direction of the terminal QRS forced

20
Q

LBBB

A

Main criteria:
-Prolonged QRS
-Wide R wave in leads 1 and V6
Other criteria:
-QRS waves have tall R waves with prolonged duration and either nothced or flattened tops of the complexes
-true rabbit ears are less likely than in RBBB
-Leads over RV show reciprocal, broad, deep S waves

21
Q

BBB plus LVH or RVH

A
  • NOT POSSIBLE TO DIAGNOSE LVH OR RVH IN THE SETTING OF LBBB(for LVH) or RBBB(for RVH)
  • some texts indicate that RVH is likely if the R’ in V1 is >15mm
22
Q

Hemiblock definition

A

when one of the fascicles of the LBB is blocked

23
Q

3 LBB fascicles

A

anterior, posterior, septal

-septal not involved in hemiblocks

24
Q

Key to detecting a hemiblock

A
  • CHANGE IN THE QRS AXIS but the QRS DURATION IS NOT PROLONGED, unless there is concomitant RBBB
  • the right bundle does not divide into separate fascicles
25
Q

Left Anterior Hemiblock definition

A

blocked conduction down the left anterior fascicle

-mean axis is directed up and to the left

26
Q

Left Anterior Hemiblock EKG findings

A
  • LAD (minus 45-minus 90)*
  • tall R waves in leads 1
  • Deep S waves in aVf
  • Usually normal QRS duration
27
Q

Left Posterior Hemiblock definition

A

posterior fascicle is blocks

-depolarization moves downward and to the right

28
Q

Left Posterior Hemiblock EKG findings

A
  • RAD (>/=+120 TO +180)*
  • normal QRS +120)
  • no evidence of RVH or anterior infarction
29
Q

What do you want to do for left posterior hemiblock before diagnosing?

A
  • exclude other causes of RAD: cor pulmonale, pulm HTN etc
  • no evidence of RVH or anterior infarction
  • LPHB may be difficult to dx w/o prior EKGs
30
Q

Bifascicular Block definition

A
  • RBBB plus with LAHB or LPHB (LPHB is uncommon)

- features of RBBB plus frontal plane features of the fascicular block-axis deviation

31
Q

Bifascicular Block EKG findings

A
  • RBBB + LAHB (LAD of -45 to -90)

- RBBB + LPHB (RAD of >+120)

32
Q

Nonspecific IVCD

A

-when either QRS IS PROLONGED w/o features of RBBB or LBBB this is called nonspecific intraventricular delay (or defect)

33
Q

Nonspecific IVCD EKG findings

A
  • QRS duration >0.11s indication slowed conduction of the ventricles
  • criteria for specific bundle branch or fascicular blocks not met
34
Q

Causes of nonspecific IVCD

A
  • Ventricular hypertrophy (esp LVH)
  • MI (so called PERIINFARCTION BLOCKS)
  • Certain antiarrhythmic drugs (quinidine, flecainide)
  • Hyperkalemia
35
Q

Preexcitation Syndrome

A
  • accessory conduction pathways sometimes exist between atria and ventricles
  • Bypass AV node and bundle of His and allow early depolarization of ventricles
  • RESULTS IN SHORT PR INTERVAL
36
Q

Preexcitation Syndrome examples

A
  • WPW:bundle of kent

- LGL: James fibers

37
Q

Wolff-Parkinson-White Syndrome EKG findings

A
  • PR interval
38
Q

WPW patients at risk for:

39
Q

Delta Wave

A

-seen in WPW-sloping upward of PR segment…cannot calculate PR segment

40
Q

Lown-Ganong -Levine Syndrome

A

-Intranodal accessory pathway (JAMES FIBERS) bypasses the normal delay in AV node-PR interval

EKG (5 decks)

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