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Pathological Q Wave

Pathological Q wave

Physiological Q Wave
ECG and Physiological Q Wave
Electrical Window (Infarction) and Pathological Q Wave
Pathological Q Wave and Infarction
ECG and Pathological Q Wave
Infarction Q Wave
Pseudo-Infarction Q Wave
Causes of Pathological Q Wave
Myocardial Infarction Q Wave
Pseudo-Myocardial Infarction Q Wave
Positional Q Wave

Physiological Q Wave

ECG limb leads septal depolarization vector, normal Q wave (aVL, I)

ECG chest leads, septal depolarization vector, normal Q wave

Physiological Q Wave

Physiological Q Wave occurs in lateral leads (aVL, I, V5, V6)
It is created by the septal depolarization vector (V_S), which directs away from the lateral leads
The Q wave can also appear in leads aVR and III, but this Q wave is created by the main ventricular vector (V_M)

ECG and Physiological Q Wave

Develop normal Q wave, septum depolarization electrical activity

Width < 0.03s (< 1 small square)
Depth < 3mm (< 3 small squares)

Only in aVR and III can it exceed 3mm; this is a normal variant (related to the main ventricular vector)

Does not exceed 1/4 of the R wave in the given lead
Common in lateral leads (aVL, I, V5, V6)

Should not be present in leads V1-V3

Electrical Window (Infarction) and Pathological Q Wave

Develop pathologic Q wave, electrical hole, previous myocardial infarction

Pathological Q wave is large (exceeds the specified dimensions)
The most common cause is electrical window in the case of myocardial infarction
In the case of infarction, myocardial necrosis occurs

Which creates an electrical window

The electrical window does not create a vector

Leads "only look through" the window
Pathological Q wave appears in leads above the electrical window

Pathological Q Wave and Infarction

Occurs after infarction due to the electrical window (after STEMI, sometimes also after NSTEMI)
Most commonly occurs within the first 9 hours after infarction

Can occur from a few minutes up to 24 hours after infarction
Pathological Q can occur in the acute or subacute stage of infarction

The time of occurrence depends on the collateral circulation of the occluded artery
Occasionally, it may temporarily occur during ischemia, without infarction

Evolution of STEMI infarction, Development of pathological Q wave in subacute and chronic stages of STEMI

STEMI Stages

Typical ECG dynamics are present in only STEMI infarction, not NSTEMI
In clinical practice, STEMI is divided into 3 stages based on ECG findings:

Acute STEMI

Shows ST elevations without Q wave
Duration: minutes to hours

Subacute STEMI

Shows ST elevations and Q wave
Duration: hours to days

Old STEMI

Shows Q wave without ST elevations
Duration: > one week

ECG and Pathological Q Wave

Pathological Q wave is large or occurs in incorrect leads

Pathological Q (One of the following conditions must be met):

Width > 0.03s
Depth > 3mm
Exceeds 1/4 of the R wave in the lead
Present in leads V1-V3

Q wave should not be present in these leads

Pathological Q wave may be in leads aVR and III

This Q wave is created by the main left ventricular vector

and not by the septal vector

Old Inferior STEMI

Pathological Q wave in inferior leads (II, III, aVF)
This is indicative of old inferior STEMI

Infarction Q Wave

Infarction is the most common cause of pathological Q wave (electrical window)
Pathological Q wave appears within a few minutes up to 24 hours after the infarction

It most commonly appears within the first 9 hours after the infarction

It is present in at least 2 adjacent leads above the electrical window (infarction localization)

Pseudo-Infarction Q Wave

It is a pathological Q wave from a cause other than infarction

Causes of Pathological Q Wave

Etiology	Localization
Myocardial Infarction (MI) (older term: Q infarction)	Above the electrical window	After inferior MI, Q appears in (II, III, aVF); after anterior MI, Q appears in (V1-V3)
Left Bundle Branch Block (LBBB)	V1-V3, III, aVF	Impulse spreads to the right ventricle through the Tawara branch. Then, the impulse spreads to the left ventricle through the myocardium. The vector thus directs from the right ventricle to the left ventricle, from leads V1-V3, III, and aVF.
Left Anterior Hemiblock	II, III, aVF	The main cardiac vector turns away from leads II, III, aVF, where a pathological Q wave may occur
Left Posterior Hemiblock	I, aVL	The main cardiac vector turns away from leads I, aVL, where a pathological Q wave may occur
Pulmonary Embolism	III	Causes overload and dilation of the right heart. The main cardiac axis shifts to the right. 20% of patients with pulmonary embolism have a pathological Q wave in lead III. It causes the S1Q3T3 pattern
Infiltrative Diseases	V1-V3	In amyloidosis, pathological proteins deposit in the myocardium, which may cause a pathological Q wave
WPW Syndrome	II, III, aVF	In WPW syndrome, ventricles are activated through two pathways (AV node and accessory pathway). Vectors in the ventricles can create a pathological Q wave
Myocarditis	Above a certain area of the heart	Myocarditis can cause pathological Q waves above a certain area of the heart
Cardiac Contusion	Above the affected area	Contusion (bruising) of the heart can cause a pathological Q wave
Chest Deformities	Above the affected area	Chest deformities may create a pathological Q wave due to altered electrical conduction
Misplaced Electrodes	I, aVL	Misplaced limb leads can produce a pathological Q wave
Hypertrophic Cardiomyopathy	(aVL, I, V5, V6), or (II, III, aVF)	Hypertrophy of the ventricular septum can increase the septal vector and cause a pathological Q wave
Positional Q Waves	III	Positional Q waves appear in lead III during deep expiration, due to the rotation of the heart as the main cardiac vector turns away from lead III

Myocardial Infarction Q Wave

ECG criteria pathologic Q wave, subacute antero-septal STEMI infarction

Subacute Antero-Septal Infarction

ST Elevations (V1-V5)
Pathological Q (V1-V3)

Physiological Q wave is never in V1-V3
Width > 0.03mm
Depth > 3mm

Myocardial Infarction and ECG

ECG old antero-septal STEMI infarction, pathological Q wave (V1-V3)

Old Antero-Septal Infarction

Negative T Waves (V2-V5)
Pathological Q (V1-V4)

Physiological Q wave is never in V1-V4
Width > 0.03mm
Depth > 3mm

ECG pathological Q wave in inferior leads (II, III, aVF), old inferior STEMI infarction

Old Inferior Infarction

Negative T Waves in inferior leads (II, III, aVF)
Pathological Q (II, III, aVF)

Width > 0.03mm
Depth > 3mm

Pseudo-Myocardial Infarction Q Wave

Left Bundle Branch Block

Wide QRS > 0.12s
Dominant S (V1)
Dominant R (V6)
Pathological Q (V1-V3)

Physiological Q wave is never in V1-V3
Width > 0.03mm
Depth > 3mm

In III and aVF, there is an rS configuration, which is not a pathological Q wave
Left Bundle Branch Block

ECG pathologic Q wave, left anterior hemiblock (LAH)

Left Anterior Fascicular Block

Left Axis Deviation > -45º

Inferior leads (II, III, aVF) are negative

In the inferior leads (II, III, aVF), there is no QS (pathological Q), but rather an rS configuration
- Notice a tiny r wave before the deep S wave (II, III, aVF)
Sometimes, however, QS, i.e., pathological Q, can occur with this hemiblock
Left Anterior Fascicular Block

ECG pathologic Q wave, left posterior hemiblock

Left Posterior Fascicular Block

Right Axis Deviation > +90º

Inferior leads (III, aVF) are predominantly positive
Lateral leads (I, aVL) are predominantly negative

In the leads (I, aVL, V1), there is no QS (pathological Q), but rather an rS configuration
- Notice a tiny r wave before the S wave
Sometimes, however, QS, i.e., pathological Q, can occur with this hemiblock
In leads aVR and III, deep Q > 3mm is not considered pathological
Left Posterior Fascicular Block

Acute Pulmonary Embolism

Extreme Right Axis Deviation +180º (Dominant R in aVR)
Right Bundle Branch Block

Wide QRS > 0.12s
Rsr in V1 (right bunny ears should be higher - rsR, but the axis is extremely deviated to the right)

Acute pulmonary embolism also creates the triad S1 Q3 T3

Negative S (in lead I)
Deep Q (in lead III)
Negative T (in lead III)

Pathological Q in lead III > 3mm

Such deep Q in aVR and III can also be found in healthy individuals and may not indicate pathology
If the patient meets additional criteria for pulmonary embolism, this deep Q is definitely pathological

WPW Syndrome

Shortened PQ interval < 0.12s
Delta Wave

Widened lower part of the QRS, best seen in (I, aVL, V4-V6)

Pathological Q in III, aVF (in aVR, Q is almost always deep - this is a variant of normal)

Width > 0.03mm
Depth > 3mm
This is not a past inferior wall infarction, but WPW Syndrome, as a delta wave is present
In WPW, the ventricles are activated through two pathways (AV node and Kent bundle)

A pathological vector forms in the ventricles, creating a pathological Q wave (III, aVF)

ECG limb leads reversal displacement, develop pathologic Q wave

Swapped ECG Leads on the Arms

The main cardiac vector directs towards the left ventricle
- Towards the lateral leads (I, aVL, V5-6), so there is a dominant R wave in these leads
- Away from the aVR lead, so a deep Q in aVR is present, which is not considered pathological
This ECG has swapped arm leads, because:

Pathological Q (I, aVL)
High positive R wave in aVR
Dominant R in V4-V6

A similar pattern can be created by:

Pathological Q (V1-2) indicates a possible old septal infarction

Hypertrophic Cardiomyopathy

Left Ventricular Hypertrophy

Positive Sokolow index: S in V2 + R in V6 > 35mm

Pathological Q (I, aVL, V5-V6)

Width > 0.03mm
Depth > 3mm

In hypertrophic cardiomyopathy, there is also hypertrophy of the ventricular septum

which creates a larger vector, and thus a larger Q wave (in the lateral leads)

Positional Q Wave

If a patient has a high diaphragm (obesity, lying down, during exhalation)

The main cardiac vector (V_M) is directed upward-left and points away from lead III

A pathological Q wave may thus appear in lead III

Width > 0.03mm
Depth > 3mm

Q wave can also appear in adjacent leads (II, aVF)

but in these leads it usually does not have pathological parameters

Positional Q can occur in patients who take deep breaths during ECG recording (changing the cardiac axis)

It appears during exhalation
Disappears during inhalation

If a patient has had a lower wall infarction (inferior infarction), then pathological Q (II, III, aVF) is present regardless of breathing
If pathological Q disappears with deep inhalation from lead III

it is physiological Q (a normal variant)

ECG lead III large pathologic respiratory q wave, due to electrical axis deviation during respiration

Positional (Respiratory) Q

Deep exhalation

The diaphragm rises, and the apex of the heart turns upward-left
The main cardiac vector also turns upward-left and points away from lead III
Pathological Q wave forms in lead III

Deep inhalation

The diaphragm falls, and the apex of the heart turns downward-right
The main cardiac vector also turns downward-right and starts pointing toward lead III
The R wave increases
and the Q wave disappears

This cycle repeats with deep breathing, meaning the Q wave in lead III appears and disappears

It is positional (respiratory) Q wave

Sources

ECG from Basics to Essentials Step by Step
litfl.com
ecgwaves.com
metealpaslan.com
medmastery.com
uptodate.com
ecgpedia.org
wikipedia.org
Strong Medicine
Understanding Pacemakers

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Pathological Q Wave

Pathological Q wave

Physiological Q Wave
ECG and Physiological Q Wave
Electrical Window (Infarction) and Pathological Q Wave
Pathological Q Wave and Infarction
ECG and Pathological Q Wave
Infarction Q Wave
Pseudo-Infarction Q Wave
Causes of Pathological Q Wave
Myocardial Infarction Q Wave
Pseudo-Myocardial Infarction Q Wave
Positional Q Wave

Physiological Q Wave

Physiological Q Wave occurs in lateral leads (aVL, I, V5, V6)
It is created by the septal depolarization vector (V_S), which directs away from the lateral leads
The Q wave can also appear in leads aVR and III, but this Q wave is created by the main ventricular vector (V_M)

ECG and Physiological Q Wave

Width < 0.03s (< 1 small square)
Depth < 3mm (< 3 small squares)

Only in aVR and III can it exceed 3mm; this is a normal variant (related to the main ventricular vector)

Does not exceed 1/4 of the R wave in the given lead
Common in lateral leads (aVL, I, V5, V6)

Should not be present in leads V1-V3

Electrical Window (Infarction) and Pathological Q Wave

Pathological Q wave is large (exceeds the specified dimensions)
The most common cause is electrical window in the case of myocardial infarction
In the case of infarction, myocardial necrosis occurs

Which creates an electrical window

The electrical window does not create a vector

Leads "only look through" the window
Pathological Q wave appears in leads above the electrical window

Pathological Q Wave and Infarction

Occurs after infarction due to the electrical window (after STEMI, sometimes also after NSTEMI)
Most commonly occurs within the first 9 hours after infarction

Can occur from a few minutes up to 24 hours after infarction
Pathological Q can occur in the acute or subacute stage of infarction

The time of occurrence depends on the collateral circulation of the occluded artery
Occasionally, it may temporarily occur during ischemia, without infarction

STEMI Stages

Typical ECG dynamics are present in only STEMI infarction, not NSTEMI
In clinical practice, STEMI is divided into 3 stages based on ECG findings:

Acute STEMI

Shows ST elevations without Q wave
Duration: minutes to hours

Subacute STEMI

Shows ST elevations and Q wave
Duration: hours to days

Old STEMI

Shows Q wave without ST elevations
Duration: > one week

ECG and Pathological Q Wave

Pathological Q wave is large or occurs in incorrect leads

Pathological Q (One of the following conditions must be met):

Width > 0.03s
Depth > 3mm
Exceeds 1/4 of the R wave in the lead
Present in leads V1-V3

Q wave should not be present in these leads

Pathological Q wave may be in leads aVR and III

This Q wave is created by the main left ventricular vector

and not by the septal vector

Old Inferior STEMI

Pathological Q wave in inferior leads (II, III, aVF)
This is indicative of old inferior STEMI

Infarction Q Wave

Infarction is the most common cause of pathological Q wave (electrical window)
Pathological Q wave appears within a few minutes up to 24 hours after the infarction

It most commonly appears within the first 9 hours after the infarction

It is present in at least 2 adjacent leads above the electrical window (infarction localization)

Pseudo-Infarction Q Wave

It is a pathological Q wave from a cause other than infarction

Causes of Pathological Q Wave

Etiology	Localization
Myocardial Infarction (MI) (older term: Q infarction)	Above the electrical window	After inferior MI, Q appears in (II, III, aVF); after anterior MI, Q appears in (V1-V3)
Left Bundle Branch Block (LBBB)	V1-V3, III, aVF	Impulse spreads to the right ventricle through the Tawara branch. Then, the impulse spreads to the left ventricle through the myocardium. The vector thus directs from the right ventricle to the left ventricle, from leads V1-V3, III, and aVF.
Left Anterior Hemiblock	II, III, aVF	The main cardiac vector turns away from leads II, III, aVF, where a pathological Q wave may occur
Left Posterior Hemiblock	I, aVL	The main cardiac vector turns away from leads I, aVL, where a pathological Q wave may occur
Pulmonary Embolism	III	Causes overload and dilation of the right heart. The main cardiac axis shifts to the right. 20% of patients with pulmonary embolism have a pathological Q wave in lead III. It causes the S1Q3T3 pattern
Infiltrative Diseases	V1-V3	In amyloidosis, pathological proteins deposit in the myocardium, which may cause a pathological Q wave
WPW Syndrome	II, III, aVF	In WPW syndrome, ventricles are activated through two pathways (AV node and accessory pathway). Vectors in the ventricles can create a pathological Q wave
Myocarditis	Above a certain area of the heart	Myocarditis can cause pathological Q waves above a certain area of the heart
Cardiac Contusion	Above the affected area	Contusion (bruising) of the heart can cause a pathological Q wave
Chest Deformities	Above the affected area	Chest deformities may create a pathological Q wave due to altered electrical conduction
Misplaced Electrodes	I, aVL	Misplaced limb leads can produce a pathological Q wave
Hypertrophic Cardiomyopathy	(aVL, I, V5, V6), or (II, III, aVF)	Hypertrophy of the ventricular septum can increase the septal vector and cause a pathological Q wave
Positional Q Waves	III	Positional Q waves appear in lead III during deep expiration, due to the rotation of the heart as the main cardiac vector turns away from lead III

Myocardial Infarction Q Wave

Subacute Antero-Septal Infarction

ST Elevations (V1-V5)
Pathological Q (V1-V3)

Physiological Q wave is never in V1-V3
Width > 0.03mm
Depth > 3mm

Myocardial Infarction and ECG

Old Antero-Septal Infarction

Negative T Waves (V2-V5)
Pathological Q (V1-V4)

Physiological Q wave is never in V1-V4
Width > 0.03mm
Depth > 3mm

Old Inferior Infarction

Negative T Waves in inferior leads (II, III, aVF)
Pathological Q (II, III, aVF)

Width > 0.03mm
Depth > 3mm

Pseudo-Myocardial Infarction Q Wave

Left Bundle Branch Block

Wide QRS > 0.12s
Dominant S (V1)
Dominant R (V6)
Pathological Q (V1-V3)

Physiological Q wave is never in V1-V3
Width > 0.03mm
Depth > 3mm

In III and aVF, there is an rS configuration, which is not a pathological Q wave
Left Bundle Branch Block

Left Anterior Fascicular Block

Left Axis Deviation > -45º

Inferior leads (II, III, aVF) are negative

In the inferior leads (II, III, aVF), there is no QS (pathological Q), but rather an rS configuration
- Notice a tiny r wave before the deep S wave (II, III, aVF)
Sometimes, however, QS, i.e., pathological Q, can occur with this hemiblock
Left Anterior Fascicular Block

Left Posterior Fascicular Block

Right Axis Deviation > +90º

Inferior leads (III, aVF) are predominantly positive
Lateral leads (I, aVL) are predominantly negative

In the leads (I, aVL, V1), there is no QS (pathological Q), but rather an rS configuration
- Notice a tiny r wave before the S wave
Sometimes, however, QS, i.e., pathological Q, can occur with this hemiblock
In leads aVR and III, deep Q > 3mm is not considered pathological
Left Posterior Fascicular Block

Acute Pulmonary Embolism

Extreme Right Axis Deviation +180º (Dominant R in aVR)
Right Bundle Branch Block

Wide QRS > 0.12s
Rsr in V1 (right bunny ears should be higher - rsR, but the axis is extremely deviated to the right)

Acute pulmonary embolism also creates the triad S1 Q3 T3

Negative S (in lead I)
Deep Q (in lead III)
Negative T (in lead III)

Pathological Q in lead III > 3mm

Such deep Q in aVR and III can also be found in healthy individuals and may not indicate pathology
If the patient meets additional criteria for pulmonary embolism, this deep Q is definitely pathological

WPW Syndrome

Shortened PQ interval < 0.12s
Delta Wave

Widened lower part of the QRS, best seen in (I, aVL, V4-V6)

Pathological Q in III, aVF (in aVR, Q is almost always deep - this is a variant of normal)

Width > 0.03mm
Depth > 3mm
This is not a past inferior wall infarction, but WPW Syndrome, as a delta wave is present
In WPW, the ventricles are activated through two pathways (AV node and Kent bundle)

A pathological vector forms in the ventricles, creating a pathological Q wave (III, aVF)

Swapped ECG Leads on the Arms

The main cardiac vector directs towards the left ventricle
- Towards the lateral leads (I, aVL, V5-6), so there is a dominant R wave in these leads
- Away from the aVR lead, so a deep Q in aVR is present, which is not considered pathological
This ECG has swapped arm leads, because:

Pathological Q (I, aVL)
High positive R wave in aVR
Dominant R in V4-V6

A similar pattern can be created by:

Pathological Q (V1-2) indicates a possible old septal infarction

Hypertrophic Cardiomyopathy

Left Ventricular Hypertrophy

Positive Sokolow index: S in V2 + R in V6 > 35mm

Pathological Q (I, aVL, V5-V6)

Width > 0.03mm
Depth > 3mm

In hypertrophic cardiomyopathy, there is also hypertrophy of the ventricular septum

which creates a larger vector, and thus a larger Q wave (in the lateral leads)

Positional Q Wave

If a patient has a high diaphragm (obesity, lying down, during exhalation)

The main cardiac vector (V_M) is directed upward-left and points away from lead III

A pathological Q wave may thus appear in lead III

Width > 0.03mm
Depth > 3mm

Q wave can also appear in adjacent leads (II, aVF)

but in these leads it usually does not have pathological parameters

Positional Q can occur in patients who take deep breaths during ECG recording (changing the cardiac axis)

It appears during exhalation
Disappears during inhalation

If a patient has had a lower wall infarction (inferior infarction), then pathological Q (II, III, aVF) is present regardless of breathing
If pathological Q disappears with deep inhalation from lead III

it is physiological Q (a normal variant)

Positional (Respiratory) Q

Deep exhalation

The diaphragm rises, and the apex of the heart turns upward-left
The main cardiac vector also turns upward-left and points away from lead III
Pathological Q wave forms in lead III

Deep inhalation

The diaphragm falls, and the apex of the heart turns downward-right
The main cardiac vector also turns downward-right and starts pointing toward lead III
The R wave increases
and the Q wave disappears

This cycle repeats with deep breathing, meaning the Q wave in lead III appears and disappears

It is positional (respiratory) Q wave

Sources

ECG from Basics to Essentials Step by Step
litfl.com
ecgwaves.com
metealpaslan.com
medmastery.com
uptodate.com
ecgpedia.org
wikipedia.org
Strong Medicine
Understanding Pacemakers