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Dual Chamber Pacemaker Modes - ECG

Pacemaker dual chamber modes

Pacemaker
Stimulation Mode
Dual-Chamber Pacemaker Modes
DDD Pacing
Variants of DDD Mode
VDD Pacing
DDI Pacing
DOO Pacing
Magnet a Pacemaker
DDDR Pacing

Pacemaker

PCM is a device that is implanted under the left clavicle
It serves to control the heart rhythm

Primarily, it protects the heart from symptomatic bradycardia

It can have 1, 2, or 3 electrodes

Each electrode is inserted into a different heart chamber:

Right atrium, right ventricle, left ventricle

Through the electrodes, the pacemaker can

Sense the electrical activity of the chamber (sensing)
Stimulate the respective chamber (pacing)

Stimulation Mode

Each pacemaker is classified according to the NBG code (see the following table)

Posi- tion	I	II	III	IV	V
	Cham- ber(s) Paced	Cham- ber(s) Sensed	Response to Sensing	Rate Modula- tion	Multisite Pacing
	O = Off	O = Off	O = Off	O = Off	O = Off
	A = Atrium	A = Atrium	T = Triggered	R = Rate Modula- tion	A = Atrium
	V = Ventricle	V = Ventricle	I = Inhibited		V = Ventricle
	D = Dual (A+V)	D = Dual (A+V)	D = Dual (T+I)		D = Dual (A+V)

Dual-Chamber Pacemaker Modes

Pacemaker dual chamber leads (atrial, ventricular)

A dual-chamber pacemaker has 2 electrodes

In the right atrium and right ventricle

Dual-chamber modes are:

DDD (Tracking mode)
VDD (Tracking mode)
DDI (Non-tracking mode)
DOO (Non-tracking mode)

DDD Pacing

D - Pacing of atrium and ventricle
D - Sensing of atrium and ventricle
D - Intrinsic electrical activity (P, QRS) can inhibit or trigger pacing
The pacemaker senses intrinsic electrical activity and accordingly adjusts the pacing

DDD pacing is an almost authentic replacement for the conduction system

Pacemaker dual chamber DDD mode (atrial, ventricular)

ECG pacemaker DDD tracking mode, atrial sensing (As), Ventricular sensing (Vs), Atrial pacing (Ap), Ventricular pacing (Vp)

DDD pacing

As - Atrial sensing
Vs - Ventricular sensing
Ap - Atrial pacing
Vp - Ventricular pacing
The pacemaker is programmed

to a rate of 60/min. (1000ms)
to an AV delay of 200ms (analogous to the AV junction - PQ interval)

If no QRS occurs within 200ms after the P wave, ventricular pacing (Vp) is triggered
If no P wave occurs within 1000ms after the P wave, atrial pacing (Ap) is triggered
Green arrows indicate intrinsic cardiac activity (P, QRS)
Red arrows indicate atrial pacing (Ap) or ventricular pacing (Vp)

Variants of DDD Mode

DDD pacing can have 4 variants based on intrinsic cardiac activity (P, QRS):

AsVs
AsVp
ApVs
ApVp

ECG pacemaker DDD tracking mode AsVs (atrial sensing, ventricular pacing)

DDD Mode (AsVs)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

Intrinsic cardiac activity (P and QRS) inhibits pacing

The function of the SA node and AV conduction is preserved

The pacemaker operates in the AsVs mode

Only atrial (As) and ventricular (Vs) sensing is performed
No pacing (stimulation artifacts) is seen on the ECG, indicating complete inhibition of the pacemaker

ECG P wave tracking, DDD tracking mode AsVp (atrial sensing, ventricular pacing)

DDD Mode (AsVp)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

The SA node (P waves) functions properly

However, after the P wave, there is no intrinsic QRS (due to prolonged AV conduction > 200ms, or a block in conduction)

The pacemaker operates in the AsVp mode

It performs atrial sensing (As) and ventricular pacing (Vp)
Transmits the atrial impulse to the ventricles

The AsVp variant is sometimes referred to as P wave tracking (transmission of the P wave to the ventricles)

ECG DDD tracking mode ApVs (atrial pacing, ventricular sensing)

DDD Mode (ApVs)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

The SA node is impaired, but AV conduction is functioning properly

Following a paced P wave, a native QRS complex follows

The pacemaker operates in the ApVs mode

It performs atrial pacing (Ap) and ventricular sensing (Vs)

ECG DDD tracking mode ApVp (atrial pacing, ventricular pacing)

DDD Mode (ApVp)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

Both the SA node and AV conduction are impaired
The pacemaker operates in the ApVp mode

It performs atrial pacing (Ap) and ventricular pacing (Vp)

VDD Pacing

V - Ventricular pacing
D - Atrial and ventricular sensing
D - Intrinsic electrical activity (P, QRS) can inhibit or trigger ventricular pacing
The pacemaker cannot pace the atrium, it is used to maintain AV conduction

Pacemaker dual chamber VDD mode (atrial, ventricular)

VDD Pacing

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

The 1st P-QRS complex is intrinsic, the pacemaker only performs sensing (AsVs)
The 2nd P wave is intrinsic, and the pacemaker performs sensing (As)
However, no intrinsic QRS follows within 200ms, so the pacemaker activates ventricular pacing (Vp) - indicated by the red arrow

Ventricular pacing is always activated if no intrinsic QRS follows the P wave within 200ms

After a ventricular extrasystole (second last QRS), ventricular pacing (Vp) occurs 1000ms later without an intrinsic P wave

The pacemaker preempted the SA node

In this case, AV synchronization is not maintained with VDD pacing (which would be maintained with DDD mode)

A patient with VDD pacing must have an intact SA node

DDI Pacing

D - Pacing both atrium and ventricle
D - Sensing both atrium and ventricle
I - Intrinsic electrical activity (P, QRS) inhibits pacing (of the ventricle or atrium)
DDI is a combination of AAI and VVI modes, which operate independently of each other

DDI Pacing

The pacemaker is programmed at a rate of 70/min. (857ms)
The DDI mode is a combination of AAI and VVI modes, operating independently

AAI: If no P wave occurs within 857ms after an intrinsic P wave, atrial pacing is triggered
VVI: If no QRS occurs within 857ms after an intrinsic QRS, ventricular pacing is triggered

Towards the end of the ECG, the frequency of intrinsic P waves increases, but the ventricular pacing rate does not increase
DDI is used in sick sinus syndrome with paroxysms of supraventricular tachycardia

DOO Pacing

D - Pacing both atrium and ventricle
O - Sensing is off
O - Response to sensing is off
This mode represents asynchronous pacing of the atrium and ventricle, regardless of intrinsic cardiac activity

DOO Pacing

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

This mode represents asynchronous pacing of the atrium and ventricle

which is activated by placing a magnet on the chest

Magnet a Pacemaker

Pacemaker magnet, reed switch, VOO, AOO, DOO

Each pacemaker has a reed switch

Which is activated in a magnetic field
A magnet is used for activation

Placed on the chest over the pacemaker

Magnet placement on the chest:

Turns off sensing
Activates asynchronous pacing

Magnet

Switches the pacemaker to asynchronous pacing:

VVI => V00
AAI => A00
DDD => D00

Used to check the pacemaker battery

If asynchronous pacing does not activate, the battery is depleted

Deactivates ICD (Implantable Cardioverter Defibrillator)
Terminates pacemaker-mediated tachycardia

By activating asynchronous pacing

DDDR Pacing

D - Pacing of both atrium and ventricle
D - Sensing of both atrium and ventricle
D - The intrinsic electrical activity (P, QRS) can inhibit or trigger pacing
R - (Rate response, Rate modulation)

The pacemaker adjusts the pacing rate according to the body's needs

The pacemaker senses the intrinsic electrical activity of the chamber and adjusts the pacing accordingly
DDDR pacing is an almost authentic replacement of the conduction system, with rate adaptation

Chronotropic Incompetence

Is the inability of the heart to appropriately adjust the rate to the body's needs

For example, during exercise, stress, climbing stairs

Most commonly due to SA node dysfunction in sick sinus syndrome
Some pacemakers have an implemented sensor

Which senses body vibrations during breathing or increased exertion

According to the sensor's information, the pacemaker adjusts the pacing rate

These pacemakers have an "R" on the IV. position: DDDR

Pacemaker dual chamber DDDR mode (atrial, ventricular)

ECG pacemaker DDDR pacing mode (Rate response, Rate modulation)

DDDR Pacing (ApVp)

The pacemaker is programmed

For rate adaptation according to the body's needs
With an AV delay of 200ms (analogous to the AV junction - PQ interval)

SA node and AV conduction are impaired
The pacemaker operates in ApVp mode

Pacing of the atrium (Ap) and pacing of the ventricle (Vp)

Adapts the pacing rate

Initially the rate is 75/min., later 100/min.

The atrial pacing rate changes, secondarily altering the ventricular pacing rate
The AV delay remains unchanged (200ms)

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 /

Dual Chamber Pacemaker Modes - ECG

Pacemaker dual chamber modes

Pacemaker
Stimulation Mode
Dual-Chamber Pacemaker Modes
DDD Pacing
Variants of DDD Mode
VDD Pacing
DDI Pacing
DOO Pacing
Magnet a Pacemaker
DDDR Pacing

Pacemaker

PCM is a device that is implanted under the left clavicle
It serves to control the heart rhythm

Primarily, it protects the heart from symptomatic bradycardia

It can have 1, 2, or 3 electrodes

Each electrode is inserted into a different heart chamber:

Right atrium, right ventricle, left ventricle

Through the electrodes, the pacemaker can

Sense the electrical activity of the chamber (sensing)
Stimulate the respective chamber (pacing)

Stimulation Mode

Each pacemaker is classified according to the NBG code (see the following table)

Position	I	II	III	IV	V
	Chamber(s) Paced	Chamber(s) Sensed	Response to Sensing	Rate Modulation	Multisite Pacing
	O = Off	O = Off	O = Off	O = Off	O = Off
	A = Atrium	A = Atrium	T = Triggered	R = Rate Modulation	A = Atrium
	V = Ventricle	V = Ventricle	I = Inhibited		V = Ventricle
	D = Dual (A+V)	D = Dual (A+V)	D = Dual (T+I)		D = Dual (A+V)

Dual-Chamber Pacemaker Modes

A dual-chamber pacemaker has 2 electrodes

In the right atrium and right ventricle

Dual-chamber modes are:

DDD (Tracking mode)
VDD (Tracking mode)
DDI (Non-tracking mode)
DOO (Non-tracking mode)

DDD Pacing

D - Pacing of atrium and ventricle
D - Sensing of atrium and ventricle
D - Intrinsic electrical activity (P, QRS) can inhibit or trigger pacing
The pacemaker senses intrinsic electrical activity and accordingly adjusts the pacing

DDD pacing is an almost authentic replacement for the conduction system

DDD pacing

As - Atrial sensing
Vs - Ventricular sensing
Ap - Atrial pacing
Vp - Ventricular pacing
The pacemaker is programmed

to a rate of 60/min. (1000ms)
to an AV delay of 200ms (analogous to the AV junction - PQ interval)

If no QRS occurs within 200ms after the P wave, ventricular pacing (Vp) is triggered
If no P wave occurs within 1000ms after the P wave, atrial pacing (Ap) is triggered
Green arrows indicate intrinsic cardiac activity (P, QRS)
Red arrows indicate atrial pacing (Ap) or ventricular pacing (Vp)

Variants of DDD Mode

DDD pacing can have 4 variants based on intrinsic cardiac activity (P, QRS):

AsVs
AsVp
ApVs
ApVp

DDD Mode (AsVs)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

Intrinsic cardiac activity (P and QRS) inhibits pacing

The function of the SA node and AV conduction is preserved

The pacemaker operates in the AsVs mode

Only atrial (As) and ventricular (Vs) sensing is performed
No pacing (stimulation artifacts) is seen on the ECG, indicating complete inhibition of the pacemaker

DDD Mode (AsVp)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

The SA node (P waves) functions properly

However, after the P wave, there is no intrinsic QRS (due to prolonged AV conduction > 200ms, or a block in conduction)

The pacemaker operates in the AsVp mode

It performs atrial sensing (As) and ventricular pacing (Vp)
Transmits the atrial impulse to the ventricles

The AsVp variant is sometimes referred to as P wave tracking (transmission of the P wave to the ventricles)

DDD Mode (ApVs)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

The SA node is impaired, but AV conduction is functioning properly

Following a paced P wave, a native QRS complex follows

The pacemaker operates in the ApVs mode

It performs atrial pacing (Ap) and ventricular sensing (Vs)

DDD Mode (ApVp)

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

Both the SA node and AV conduction are impaired
The pacemaker operates in the ApVp mode

It performs atrial pacing (Ap) and ventricular pacing (Vp)

VDD Pacing

V - Ventricular pacing
D - Atrial and ventricular sensing
D - Intrinsic electrical activity (P, QRS) can inhibit or trigger ventricular pacing
The pacemaker cannot pace the atrium, it is used to maintain AV conduction

VDD Pacing

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

The 1st P-QRS complex is intrinsic, the pacemaker only performs sensing (AsVs)
The 2nd P wave is intrinsic, and the pacemaker performs sensing (As)
However, no intrinsic QRS follows within 200ms, so the pacemaker activates ventricular pacing (Vp) - indicated by the red arrow

Ventricular pacing is always activated if no intrinsic QRS follows the P wave within 200ms

After a ventricular extrasystole (second last QRS), ventricular pacing (Vp) occurs 1000ms later without an intrinsic P wave

The pacemaker preempted the SA node

In this case, AV synchronization is not maintained with VDD pacing (which would be maintained with DDD mode)

A patient with VDD pacing must have an intact SA node

DDI Pacing

D - Pacing both atrium and ventricle
D - Sensing both atrium and ventricle
I - Intrinsic electrical activity (P, QRS) inhibits pacing (of the ventricle or atrium)
DDI is a combination of AAI and VVI modes, which operate independently of each other

DDI Pacing

The pacemaker is programmed at a rate of 70/min. (857ms)
The DDI mode is a combination of AAI and VVI modes, operating independently

AAI: If no P wave occurs within 857ms after an intrinsic P wave, atrial pacing is triggered
VVI: If no QRS occurs within 857ms after an intrinsic QRS, ventricular pacing is triggered

Towards the end of the ECG, the frequency of intrinsic P waves increases, but the ventricular pacing rate does not increase
DDI is used in sick sinus syndrome with paroxysms of supraventricular tachycardia

DOO Pacing

D - Pacing both atrium and ventricle
O - Sensing is off
O - Response to sensing is off
This mode represents asynchronous pacing of the atrium and ventricle, regardless of intrinsic cardiac activity

DOO Pacing

The pacemaker is programmed

at a rate of 60/min. (1000ms)
with an AV delay of 200ms (analogous to the AV junction - PQ interval)

This mode represents asynchronous pacing of the atrium and ventricle

which is activated by placing a magnet on the chest

Magnet a Pacemaker

Each pacemaker has a reed switch

Which is activated in a magnetic field
A magnet is used for activation

Placed on the chest over the pacemaker

Magnet placement on the chest:

Turns off sensing
Activates asynchronous pacing

Magnet

Switches the pacemaker to asynchronous pacing:

VVI => V00
AAI => A00
DDD => D00

Used to check the pacemaker battery

If asynchronous pacing does not activate, the battery is depleted

Deactivates ICD (Implantable Cardioverter Defibrillator)
Terminates pacemaker-mediated tachycardia

By activating asynchronous pacing

DDDR Pacing

D - Pacing of both atrium and ventricle
D - Sensing of both atrium and ventricle
D - The intrinsic electrical activity (P, QRS) can inhibit or trigger pacing
R - (Rate response, Rate modulation)

The pacemaker adjusts the pacing rate according to the body's needs

The pacemaker senses the intrinsic electrical activity of the chamber and adjusts the pacing accordingly
DDDR pacing is an almost authentic replacement of the conduction system, with rate adaptation

Chronotropic Incompetence

Is the inability of the heart to appropriately adjust the rate to the body's needs

For example, during exercise, stress, climbing stairs

Most commonly due to SA node dysfunction in sick sinus syndrome
Some pacemakers have an implemented sensor

Which senses body vibrations during breathing or increased exertion

According to the sensor's information, the pacemaker adjusts the pacing rate

These pacemakers have an "R" on the IV. position: DDDR

DDDR Pacing (ApVp)

The pacemaker is programmed

For rate adaptation according to the body's needs
With an AV delay of 200ms (analogous to the AV junction - PQ interval)

SA node and AV conduction are impaired
The pacemaker operates in ApVp mode

Pacing of the atrium (Ap) and pacing of the ventricle (Vp)

Adapts the pacing rate

Initially the rate is 75/min., later 100/min.

The atrial pacing rate changes, secondarily altering the ventricular pacing rate
The AV delay remains unchanged (200ms)

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