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Bundle Branch Re-entrant Tachycardia

Bundle branch reentry (reentrant) ventricular tachycardia (BBRVT)

Bundle Branch Re-entrant Tachycardia
Genesis of Bundle Branch Re-entrant Tachycardia
Mechanism of Re-entry
Division - Bundle Branch Reentry Tachycardia
Fascicular and Interfascicular Tachycardia
ECG and Bundle Branch Reentry Tachycardia

Bundle Branch Re-entrant Tachycardia

Bundle Branch Re-entrant Ventricular Tachycardia

It is a rare form of monomorphic ventricular tachycardia
Most commonly occurs in the dilated left ventricle in dilated cardiomyopathy
Mechanism is macro re-entry impulse:

Circulates through both Tawar's branches
or through both fascicles of the left Tawar's branch

Bundle branch re-entrant tachycardia does not respond to antiarrhythmic drug treatment
Relatively easy to treat with radiofrequency ablation of macro re-entry
Often recurs

Genesis of Bundle Branch Re-entrant Tachycardia

Genesis Bundle Branch Re-entry Ventricular Tachycardia

Bundle branch re-entrant tachycardia (BBRT) is initiated by a ventricular extrasystole (VES)
VES is retrogradely blocked in the right bundle branch

Because it has a longer refractory period compared to the left bundle branch

VES retrogradely travels through the left bundle branch

And reaches the His bundle

Mechanism of Re-entry

Continuation Branch Re-entrant Ventricular Tachycardia

A macro re-entry occurs

The impulse circulates through the bundle branches and ventricular septum
The slow re-entry pathway is in the left bundle branch (or in the septum)

The impulse from re-entry activates:

Retrogradely the atria
Anterogradely the ventricles through the right bundle branch

Therefore, the ECG will show a left bundle branch block

Division - Bundle Branch Reentry Tachycardia

The impulse circulates in re-entry with a frequency of 200-300/min.
We recognize 3 types of bundle branch reentry tachycardia

Type A (typical form) - the most common
Type B
Interfascicular Tachycardia - very rare

Re-entry always occurs where there is a slow pathway
Interfascicular (re-entry) tachycardia has a slow pathway in one fascicle

Therefore, re-entry passes through both fascicles
Both ventricles are activated from the fascicular area

The impulse activates the ventricles from re-entry from the bundle branch (fascicle) and then spreads anterogradely
If 2 opposing impulses meet in the bundle (fascicle), they cancel each other out (due to the refractory period)


BBRT (Type A)	BBRT (Type B)	Interfascicular Tachycardia
Anterograde: Right bundle branch	Anterograde: Left bundle branch	Anterograde: Left or right fascicle
Retrograde: Left bundle branch	Retrograde: Right bundle branch	Retrograde: Contralateral fascicle

Fascicular and Interfascicular Tachycardia

Fascicular ventricular tachycardia reentry, anterograde and retrograde conduction

Fascicular Ventricular Tachycardia

It is idiopathic (occurs due to an unknown cause in a structurally healthy heart)
The mechanism is re-entry

The fast pathway is in the fascicle
The slow pathway is in the adjacent myocardium

Interfascicular reentry with anterograde and retrograde conduction

Interfascicular Ventricular Tachycardia

Occurs in a structurally damaged heart (not idiopathic)

Most commonly seen in dilated left ventricle

Re-entry passes through both the anterior and posterior fascicles

The fast pathway is in one fascicle
The slow pathway is in the other fascicle

ECG and Bundle Branch Reentry Tachycardia

Patients often have a structural heart defect affecting the conduction system
In sinus rhythm, you might often see:

Shape of left bundle branch block (LBBB) (rarely right bundle branch block (RBBB))

It is not a block (re-entry would not occur), but slowed conduction through the bundle branch

AV block I. degree (prolonged PQ interval >0.2s)

Bundle Branch Reentry Ventricular Tachycardia (BBRT)

Wide QRS complexes (>0.12s)

In Interfascicular Tachycardia, QRS complexes can be borderline at 0.12s

Frequency 200-300/min.
Signs of ventricular tachycardia
Often present is AV dissociation (a fundamental sign of ventricular tachycardia)
Definitive diagnosis is made through electrophysiological testing


BBRT (Type A)	BBRT (Type B)	Interfascicular Tachycardia
ECG Appearance: LBBB	ECG Appearance: RBBB	ECG Appearance: RBBB
QRS Complexes >0.12s	QRS Complexes >0.12s	QRS Complexes about 0.12s
Anterograde: Right Bundle Branch	Anterograde: Left Bundle Branch	Anterograde: Left or Right Fascicle
Retrograde: Left Bundle Branch	Retrograde: Right Bundle Branch	Retrograde: Contralateral Fascicle

ECG Bundle Branch Reentry Tachycardia Type A, anterograde retrograde conduction

Bundle Branch Reentry Ventricular Tachycardia (Type A)

ECG (A) is for a patient with dilated cardiomyopathy

ECG (B) Bundle Branch Reentry Tachycardia (Type A)

Frequency approximately 200/min.

BBRT has a frequency of 200-300/min.
Other ventricular tachycardias rarely have such a high frequency

Ventricular tachycardia with LBBB pattern

Wide QRS (>0.12s)
Deep S (V1)
Dominant R (V6)

Definitive diagnosis is made through electrophysiological testing

ECG Bundle branch reentrant ventricular tachycardia, Type A

Bundle Branch Reentry Ventricular Tachycardia (Type A)

Frequency approximately 200/min.

BBRT has a frequency of 200-300/min.
Other ventricular tachycardias rarely reach such a high frequency

Pattern of left bundle branch block

Wide QRS (>0.12s)
Deep S wave (V1)
Dominant R wave (V6)

AV dissociation

P waves deform QRS complexes (V5)
AV dissociation is a key feature of ventricular tachycardia

Bundle Branch Reentry Tachycardia Type B, anterograde retrograde conduction

ECG Bundle branch reentrant ventricular tachycardia, Type B (BBRT Type B)

Bundle Branch Reentry Ventricular Tachycardia (Type B)

Frequency approximately 200/min.

BBRT has a frequency of 200-300/min.
Other ventricular tachycardias rarely have such a high frequency

Pattern of right bundle branch block

Wide QRS (>0.12s)
Dominant RsR pattern (V1)
Deep S wave (V6)

AV dissociation

In lead V3, irregular terminal portions of QRS complexes are indicated
AV dissociation is a key feature of ventricular tachycardia

ECG RBBB, left posterior fascicular block, First degree AV block

Sinus Rhythm (RBBB + AV Block I + Left Posterior Hemiblock)

Sinus Rhythm

Heart Rate 75/min.

Right Bundle Branch Block (RBBB)

Wide QRS (>0.12s)
Dominant rsR pattern (V1)
Deep S wave (V6)

AV Block I

Prolonged PQ interval (>0.2s)

Left Posterior Hemiblock (LPHB)

Dominant QRS (III, aVF)
Negative QRS (I)

RBBB + LPHB is referred to as bifascicular block
Patient with extensive conduction system disorder

where bundle branch reentry VT can occur after a ventricular extrasystole

ECG Interfascicular reentry ventricular tachycardia, anterior posterior fasciculus, anterograde retrograde conduction

ECG interfascicular reentry VT, narrow QRS complex ventricular tachycardia

Interfascicular Ventricular Tachycardia

This is an ECG from a previous patient
Heart Rate: 150/min.

RRVT usually has a rate of 200-300/min.
Despite this, it is a case of RRVT

The ECG still shows a bifascicular block (RBBB + LPHB)
AV Disassociation

In lead aVF, we see indicated P waves that deform the QRS complexes
AV disassociation is a key sign of ventricular tachycardia

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 /

Bundle Branch Re-entrant Tachycardia

Bundle branch reentry (reentrant) ventricular tachycardia (BBRVT)

Bundle Branch Re-entrant Tachycardia
Genesis of Bundle Branch Re-entrant Tachycardia
Mechanism of Re-entry
Division - Bundle Branch Reentry Tachycardia
Fascicular and Interfascicular Tachycardia
ECG and Bundle Branch Reentry Tachycardia

Bundle Branch Re-entrant Tachycardia

It is a rare form of monomorphic ventricular tachycardia
Most commonly occurs in the dilated left ventricle in dilated cardiomyopathy
Mechanism is macro re-entry impulse:

Circulates through both Tawar's branches
or through both fascicles of the left Tawar's branch

Bundle branch re-entrant tachycardia does not respond to antiarrhythmic drug treatment
Relatively easy to treat with radiofrequency ablation of macro re-entry
Often recurs

Genesis of Bundle Branch Re-entrant Tachycardia

Bundle branch re-entrant tachycardia (BBRT) is initiated by a ventricular extrasystole (VES)
VES is retrogradely blocked in the right bundle branch

Because it has a longer refractory period compared to the left bundle branch

VES retrogradely travels through the left bundle branch

And reaches the His bundle

Mechanism of Re-entry

A macro re-entry occurs

The impulse circulates through the bundle branches and ventricular septum
The slow re-entry pathway is in the left bundle branch (or in the septum)

The impulse from re-entry activates:

Retrogradely the atria
Anterogradely the ventricles through the right bundle branch

Therefore, the ECG will show a left bundle branch block

Division - Bundle Branch Reentry Tachycardia

The impulse circulates in re-entry with a frequency of 200-300/min.
We recognize 3 types of bundle branch reentry tachycardia

Type A (typical form) - the most common
Type B
Interfascicular Tachycardia - very rare

Re-entry always occurs where there is a slow pathway
Interfascicular (re-entry) tachycardia has a slow pathway in one fascicle

Therefore, re-entry passes through both fascicles
Both ventricles are activated from the fascicular area

The impulse activates the ventricles from re-entry from the bundle branch (fascicle) and then spreads anterogradely
If 2 opposing impulses meet in the bundle (fascicle), they cancel each other out (due to the refractory period)


	BBRT (Type A)	BBRT (Type B)	Interfascicular Tachycardia
Anterograde:	Right bundle branch	Left bundle branch	Left or right fascicle
Retrograde:	Left bundle branch	Right bundle branch	Contralateral fascicle

Fascicular and Interfascicular Tachycardia

Fascicular Ventricular Tachycardia

It is idiopathic (occurs due to an unknown cause in a structurally healthy heart)
The mechanism is re-entry

The fast pathway is in the fascicle
The slow pathway is in the adjacent myocardium

Interfascicular Ventricular Tachycardia

Occurs in a structurally damaged heart (not idiopathic)

Most commonly seen in dilated left ventricle

Re-entry passes through both the anterior and posterior fascicles

The fast pathway is in one fascicle
The slow pathway is in the other fascicle

ECG and Bundle Branch Reentry Tachycardia

Patients often have a structural heart defect affecting the conduction system
In sinus rhythm, you might often see:

Shape of left bundle branch block (LBBB) (rarely right bundle branch block (RBBB))

It is not a block (re-entry would not occur), but slowed conduction through the bundle branch

AV block I. degree (prolonged PQ interval >0.2s)

Bundle Branch Reentry Ventricular Tachycardia (BBRT)

Wide QRS complexes (>0.12s)

In Interfascicular Tachycardia, QRS complexes can be borderline at 0.12s

Frequency 200-300/min.
Signs of ventricular tachycardia
Often present is AV dissociation (a fundamental sign of ventricular tachycardia)
Definitive diagnosis is made through electrophysiological testing


	BBRT (Type A)	BBRT (Type B)	Interfascicular Tachycardia
ECG Appearance:	LBBB	RBBB	RBBB
QRS Complexes	>0.12s	>0.12s	about 0.12s
Anterograde:	Right Bundle Branch	Left Bundle Branch	Left or Right Fascicle
Retrograde:	Left Bundle Branch	Right Bundle Branch	Contralateral Fascicle

Bundle Branch Reentry Ventricular Tachycardia (Type A)

ECG (A) is for a patient with dilated cardiomyopathy

ECG (B) Bundle Branch Reentry Tachycardia (Type A)

Frequency approximately 200/min.

BBRT has a frequency of 200-300/min.
Other ventricular tachycardias rarely have such a high frequency

Ventricular tachycardia with LBBB pattern

Wide QRS (>0.12s)
Deep S (V1)
Dominant R (V6)

Definitive diagnosis is made through electrophysiological testing

Bundle Branch Reentry Ventricular Tachycardia (Type A)

Frequency approximately 200/min.

BBRT has a frequency of 200-300/min.
Other ventricular tachycardias rarely reach such a high frequency

Pattern of left bundle branch block

Wide QRS (>0.12s)
Deep S wave (V1)
Dominant R wave (V6)

AV dissociation

P waves deform QRS complexes (V5)
AV dissociation is a key feature of ventricular tachycardia

Bundle Branch Reentry Ventricular Tachycardia (Type B)

Frequency approximately 200/min.

BBRT has a frequency of 200-300/min.
Other ventricular tachycardias rarely have such a high frequency

Pattern of right bundle branch block

Wide QRS (>0.12s)
Dominant RsR pattern (V1)
Deep S wave (V6)

AV dissociation

In lead V3, irregular terminal portions of QRS complexes are indicated
AV dissociation is a key feature of ventricular tachycardia

Sinus Rhythm (RBBB + AV Block I + Left Posterior Hemiblock)

Sinus Rhythm

Heart Rate 75/min.

Right Bundle Branch Block (RBBB)

Wide QRS (>0.12s)
Dominant rsR pattern (V1)
Deep S wave (V6)

AV Block I

Prolonged PQ interval (>0.2s)

Left Posterior Hemiblock (LPHB)

Dominant QRS (III, aVF)
Negative QRS (I)

RBBB + LPHB is referred to as bifascicular block
Patient with extensive conduction system disorder

where bundle branch reentry VT can occur after a ventricular extrasystole

Interfascicular Ventricular Tachycardia

This is an ECG from a previous patient
Heart Rate: 150/min.

RRVT usually has a rate of 200-300/min.
Despite this, it is a case of RRVT

The ECG still shows a bifascicular block (RBBB + LPHB)
AV Disassociation

In lead aVF, we see indicated P waves that deform the QRS complexes
AV disassociation is a key sign of ventricular tachycardia

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