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Ventricular Tachycardia: Focus and Localization

Localisation of the origin of a ventricular tachycardia

Ventricular Tachycardia
Localization of VT Focus
Epicardial VT

Ventricular Tachycardia

Ventricular tachycardia (VT) has a ventricular ectopic focus

below the His bundle
Produces specific ECG signs

The focus generates impulses with a frequency > 100/min.

The mechanism of impulses can be:

Re-entry (most common)
Increased automaticity
Triggered activity

Produces wide QRS complexes (>0.12s)

Rarely, the QRS complexes are narrow (VT from the septal region, Fascicular VT)

A ventricular ectopic focus creates a ventricular electrical vector

Which then depolarizes the ventricles and produces QRS complexes

Based on the ECG waveform, the ectopic focus in the ventricles can be localized

Localization of VT Focus

The ectopic focus in VT can be localized to the main cardiac regions:

Right ventricle, left ventricle, septum, apex, base, inferior wall of the heart

ECG finding:	Localization:
QRS Morphology:
Shape of LBBB	Left ventricular septum, Right ventricle, Bundle branch reentry VT
Shape of RBBB	Left ventricle outside the septum
Cardiac Axis:
Superior	Inferior wall
Inferior	Upper septum, Upper lateral wall
Rightward	Left lateral wall, Apex
Transition Zone:
Transition zone ≤ V3	Base of the heart
Transition zone ≥ V4	Apex of the heart
Precordial Concordance:
Positive	Base of the heart
Negative	Apex of the heart

Ventricular Tachycardia

On the ECG, there is ventricular tachycardia
QRS Morphology: RBBB
Cardiac Axis: Superior
Transition Zone: V3
Ectopic Focus is:

in the left ventricle outside the septum
on the inferior wall
at the base of the heart

Epicardial VT

Epicardial ectopic focus locasisation, ventricular tachycardia, Localisation of the origin of a ventricular tachycardia, ectopic focus

Epicardial ectopic focus in ventricular tachycardia

Vector depolarizes the ventricles transmurally to the endocardium

There is a prolonged onset of the QRS complex
During ventricular tachycardia, on the ECG:

Pseudo-delta wave that widens the base of the QRS complexes

It is not a delta wave seen in WPW syndrome

Prolonged RS interval
Prolonged R wave peak time

ECG Criteria:	Definition:
Pseudo delta wave ≥ 35ms	From the beginning of the QRS to the end of the pseudo delta wave In any precordial lead
Prolonged R wave peak time ≥ 85ms	From the beginning of the QRS to the peak of the R wave In lead V2
RS interval ≥ 120ms	From the beginning of the QRS to the peak of the S wave In any lead

Criteria apply only to VT with a BPTR pattern
VT with a BĽTR pattern usually has focus in the septal area of the ventricles

where epicardium is absent

ECG epicardial ventricular tachycardia, pseudo delta wave, RS interval, Intrinsicoid deflection,

Ventricular Tachycardia

The ECG shows ventricular tachycardia
QRS Morphology: RBBB
Heart Axis: Superior
Transition Zone: V4
Ectopic Focus is:

in the left ventricle, excluding the septum
on the inferior wall
at the heart apex

The ectopic focus is in the endocardium

Ventricular Tachycardia

The ECG shows ventricular tachycardia
QRS Morphology: RBBB
Heart Axis: Superior
Transition Zone: V3
Ectopic Focus is:

in the left ventricle, excluding the septum
on the inferior wall
at the heart base

The ectopic focus is in the endocardium

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

Home /

Ventricular Tachycardia: Focus and Localization

Localisation of the origin of a ventricular tachycardia

Ventricular Tachycardia
Localization of VT Focus
Epicardial VT

Ventricular Tachycardia

Ventricular tachycardia (VT) has a ventricular ectopic focus

below the His bundle
Produces specific ECG signs

The focus generates impulses with a frequency > 100/min.

The mechanism of impulses can be:

Re-entry (most common)
Increased automaticity
Triggered activity

Produces wide QRS complexes (>0.12s)

Rarely, the QRS complexes are narrow (VT from the septal region, Fascicular VT)

A ventricular ectopic focus creates a ventricular electrical vector

Which then depolarizes the ventricles and produces QRS complexes

Based on the ECG waveform, the ectopic focus in the ventricles can be localized

Localization of VT Focus

The ectopic focus in VT can be localized to the main cardiac regions:

Right ventricle, left ventricle, septum, apex, base, inferior wall of the heart

ECG finding:	Localization:
QRS Morphology:
Shape of LBBB	Left ventricular septum, Right ventricle, Bundle branch reentry VT
Shape of RBBB	Left ventricle outside the septum
Cardiac Axis:
Superior	Inferior wall
Inferior	Upper septum, Upper lateral wall
Rightward	Left lateral wall, Apex
Transition Zone:
Transition zone ≤ V3	Base of the heart
Transition zone ≥ V4	Apex of the heart
Precordial Concordance:
Positive	Base of the heart
Negative	Apex of the heart

Ventricular Tachycardia

On the ECG, there is ventricular tachycardia
QRS Morphology: RBBB
Cardiac Axis: Superior
Transition Zone: V3
Ectopic Focus is:

in the left ventricle outside the septum
on the inferior wall
at the base of the heart

Epicardial VT

Epicardial ectopic focus in ventricular tachycardia

Vector depolarizes the ventricles transmurally to the endocardium

There is a prolonged onset of the QRS complex
During ventricular tachycardia, on the ECG:

Pseudo-delta wave that widens the base of the QRS complexes

It is not a delta wave seen in WPW syndrome

Prolonged RS interval
Prolonged R wave peak time

ECG Criteria:	Definition:
Pseudo delta wave ≥ 35ms	From the beginning of the QRS to the end of the pseudo delta wave In any precordial lead
Prolonged R wave peak time ≥ 85ms	From the beginning of the QRS to the peak of the R wave In lead V2
RS interval ≥ 120ms	From the beginning of the QRS to the peak of the S wave In any lead

Criteria apply only to VT with a BPTR pattern
VT with a BĽTR pattern usually has focus in the septal area of the ventricles

where epicardium is absent

Ventricular Tachycardia

The ECG shows ventricular tachycardia
QRS Morphology: RBBB
Heart Axis: Superior
Transition Zone: V4
Ectopic Focus is:

in the left ventricle, excluding the septum
on the inferior wall
at the heart apex

The ectopic focus is in the endocardium

Ventricular Tachycardia

The ECG shows ventricular tachycardia
QRS Morphology: RBBB
Heart Axis: Superior
Transition Zone: V3
Ectopic Focus is:

in the left ventricle, excluding the septum
on the inferior wall
at the heart base

The ectopic focus is in the endocardium

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