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NSU AA Denver: Winter 2025 (1st Semester) > 2025 ECG Quiz 3 > Flashcards

2025 ECG Quiz 3 Flashcards

Cardiac Axis, Hypertrophy and Enlargement (44 cards)

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1
Q

Electrical Axis of the Heart

A

The axis is in reference to the electrical activity of the QRS complex (ventricular depolarization)

Axis: orientation of the mean electrical vector

First vector: septal depolarization

Late vectors: progression of ventricular depolarization

Mean vector: average vector of all instantaneous vectors

Mean electrical axis: direction of mean vector

Mean QRS vector: usually points left and inferiorly

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2
Q

Normal Axis

A

If the QRS complex axis lies within the shaded quadrant shown here, it is normal.

If the QRS complex is (+) in leads I and aVF, the QRS axis must be normal.

0-90+ = normal

Some cardiologists say -30 works for normal… NOT FOR US!!!

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3
Q

Determining Normal Axis Lead I

A

-90 to 90 degrees: Positive QRS complex in Lead I

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4
Q

Determining Normal Axis aVF

A

0 to 180 degrees: Positive QRS complex in lead aVF

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5
Q

Determining Normal Axis Lead I and aVF

A

If the QRS complex is positive in both leads I and aVF, the QRS axis is normal.

If the QRS complex in either lead I or aVF is not positive, the QRS axis is not normal

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6
Q

Defining Axis Precisely

A

Identify a biphasic QRS complex in a limb lead.

Look for an iso-electric biphasic wave.

Axis must be perpendicular to this lead.

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7
Q

Actual ECG of Normal Axis

A

Positive deflection in Lead I and aVF means normal axis

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8
Q

Abnormal Electrical Axis

A

Rule of thumb: the heart axis rotates towards hypertrophy and away from infarction

Direction of vector changes under various circumstances:
Rotation: the heart itself is rotated. (ex. Right ventricular overload)

Hypertrophy: axis will deviate towards the greater electrical activity. (increased electrical activity)

Infarction: Myocardial tissue is electrically dead. QRS vector turns away from this tissue.

Conduction abnormalities: influence mean electrical vector. Right Bundle Branch Block can shift it.

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9
Q

Right Axis Deviation

A

Right ventricular hypertrophy

Old lateral STEMI

Posterior fascicular block

Electrical axis is between +90 and 180 degrees

If the QRS is predominantly negative in lead I and positive in lead aVF, then the axis is deviated to the right.

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10
Q

Right Axis Deviation on ECG

A
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11
Q

Extreme Right Axis Deviation

A

Northwest Axis or Superior Axis Deviation

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12
Q

Left Axis Deviation

A

Left ventricular hypertrophy

Old inferior STEMI

Left bundle branch block (LBBB) Anterior fascicular block

Electrical axis is between -90 and 0 degrees.

If the QRS is predominantly positive in lead I and negative in lead aVF, then the axis is left and upwards.

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13
Q

Left Bundle Branch Block Causing Left Axis Deviation

A
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14
Q

Left Axis Deviation on ECG

A
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15
Q

Axis Summary

A
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16
Q

Axis Summary

A
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17
Q

Axis Summary

A
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18
Q

Practice ECG

19
Q

Practice ECG

20
Q

Hypertrophy vs Enlargement

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A

HYPERTROPHY:
Increase in myocardial muscle mass.

Result of chronic pressure overload

Heart must pump harder to overcome increased resistance

Think: Pressure and Stenosis of Valve(s) and Hypertension

Increase in size requires more O2 for activity, and makes it harder for vessels to perfuse the tissue (arteries and veins)

ENLARGEMENT:
Dilation of a heart chamber w/out more muscle mass

Result of chronic volume overload

Chamber dilates to accommodate more blood volume

Think: volume overload, insufficient valves/regurgitation

ECG is not good distinguishing between the two

21
Q

Axis Deviation: Right and Left Ventricular Hypertrophy

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A

Left ventricular hypertrophy:
Leads to left axis deviation
LV increases dominance of mean vector over the RV
Chronic hypertension:
Heart must work harder to overcome increased pressure
LV hypertrophies
Increases dominance of mean vectors

Right ventricular hypertrophy:
Leads to right axis deviation
Uncommon, requiring significant changes in the RV
Can occur in patients with severe COPD or uncorrected congenital heart disease

22
Q

ECG Changes with Hypertrophy

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A

Increase in duration:
Chamber takes longer to depolarize

Increase in amplitude:
Chamber generates more electrical current/voltage. The typical indication

Shifts in electrical axis:
Larger percentage of total electrical current can move through the expanded chamber.

23
Q

Normal Atrial Depolarization

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A

Enlargement can be seen in Lead II and V1

24
Q

Right Atrial Enlargement

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A

Tall, peaked P waves in inferior leads and V1

Indications of right atrial enlargement (RAE)
Amplitude of >2.5mm
No change in duration

P pulmonale
Caused by increased right sided pressures, i.e. pulmonary hypertension or pulmonary valve stenosis

25
Right Atrial Enlargement in Leads
26
Right Atrial Enlargement in 12 Lead
27
Left Atrial Enlargement
Wide, notched P wave in leads I and II, as well as a wide biphasic P wave in V1 Indications of left atrial enlargement (LAE) Increased amplitude of terminal component of P wave > 1mm below isoelectric line in lead V1 Duration of terminal component of P wave is increased > 1 one small square or 0.04 seconds No significant axis deviation P mitrale Caused by increased left sided pressures, i.e. mitral valve stenosis TYPICAL Cause, mitral valve regurgitation, or systemic hypertension
28
Left Atrial Enlargement in Leads
29
Left Atrial Enlargement on 12 Lead
30
Right Ventricular Hypertrophy
Common diagnostic criteria: Increased R wave amplitude in right ventricle leads Increased S wave amplitude in left ventricle leads Common causes: Severe or chronic pulmonary disease (COPD) Pulmonary hypertension Congenital disease Tetralogy of Fallot Pulmonary valve stenosis Ventral septal defect (VSD)
31
Right Ventricular Hypertrophy in Leads
Precordial leads: R wave larger than S wave in V1 S wave larger than R wave in V5-V6 Limb leads: Right axis deviation, QRS axis > +100 degrees Predominantly negative QRS in Lead I
32
Right Ventricular Hypertrophy on Wheel
33
Left Ventricular Hypertrophy (Causes)
Common diagnostic criteria: Increased R wave amplitude in left ventricle leads Increased S wave amplitude in right ventricle leads Common causes: Systemic hypertension Aortic stenosis Athleticism
34
Left Ventricular Hypertrophy on Leads
Precordial Leads: S wave in V1 plus R wave in V5 or V6 is > 35mm Limb leads: R wave in aVL > 11mm
35
Left Ventricular Hypertrophy on Wheel
36
Left Ventricular Hypertrophy Rules
Precordial Lead Rules: BIGGER INDICATOR The R-Wave amplitude in lead V5 or V6 PLUS the S wave amplitude in lead V1 or V2 exceeds 35 mm The R-wave amplitude in lead V5 exceeds 26 mm The R-wave amplitude in lead V6 exceeds 20 mm The R-wave amplitude in lead V6 exceeds the R-wave amplitude in lead V5 Limb Lead Rules: R-wave amplitude in aVL is > 11 mm R-wave amplitude in aVF is > 20 mm The R-wave amplitude in lead I > 13 mm The R-wave amplitude in lead I PLUS the S-wave amplitude in lead III > 25 mm COMBINED: R-wave amplitude in aVL plus the S-wave amplitude in V3 is > 20 (women) and > 28 in men
37
Diagnosis of Left Ventricular Hypertrophy
S wave in V1 = 19mm R wave in V5 = 28mm 19mm + 28mm = 47mm, 47mm > 35mm
38
Secondary Repolarization Abnormalities of Ventricular Hypertrophy
Downward sloping ST segment depression T wave inversion Resulting from a change in axis so that it no longer closely aligns with the QRS axis Blends together to form a single asymmetric wave The downward slope is gradual The upward slope is sharp
39
LVH vs RVH
40
LVH or RVH?
... RVH Why???
41
LVH or RVH?
Normal Why???
42
Biventricular Hypertrophy
Left side will obscure right side electrical indications
43
Biventricular Hypertrophy in ECG
Primarily see LV indications
44
ECG Evaluation Synopsis
Look at ECG Look at Lead 1 and aVF for axis deviation Deviation to the left = look for hypertrophy indicators (V5orV6 and V1orV2 adding to over 35mm) Deviation to the right = look for hypertrophy indicators (V1 and V5-V6) See nothing (on possible ventricular hypertrophy and/or initial axis deviation evaluation), look to II and V1 for atrium issues in P waves Right Atrium Enlargement Causes: Right sided pressure Pulmonary hypertension Pulmonary valve stenosis Enlargement ECG: Tall P waves in inferior leads (Lead II particular) and V1 tall P wave with some biphasic action Left Atrium Enlargement Causes: Left sided pressure increase Mitral valve stenosis Mitral Valve regurgitation or system hypertension (Typical) Enlargement ECG: Lead II shows P waves notched mountain peak and V1 shows hill with valley Right Ventricular Hypertrophy Causes: COPD Pulmonary Hypertension Congenital Disease Tetralogy of Fallot Pulmonary Valve Stenosis Ventral Septal Defect Hypertrophy ECG: R-Wave larger than S-Wave in V1 S-Wave larger than R-Wave in V5-V6 Lead I biphasic with Lead aVF elevated R-Wave Left Ventricular Hypertrophy Causes: Systemic Hypertension Aortic Stenosis Athleticism Hypertrophy ECG: R-Wave amplitude in V5 or V6 and S-Wave amplitude in V1or V2 greater than 35mm R-Wave amplitude in V5 greater than 26mm R-Wave amplitude in V6 greater than 20mm R-Wave amplitude in V6 greater than in lead V5 R-Wave in aVL greater than 11mm

NSU AA Denver: Winter 2025 (1st Semester) (43 decks)

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