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Sinus Arrest

Sinus pause, Sinus arrest

SA Node (P and T Cells)
Sinus Pause (Sinus Arrest)
ECG and Sinus Pause (Sinus Arrest)

SA Node (P and T Cells)

The SA node consists of 2 types of cells
P cells (Pacemaker cells)

Generate impulses in the SA node and determine the heart rate

T cells (Transport cells)

Transmit impulses from P cells to the atrium and internodal pathways
If the impulse does not pass through T cells, a P wave does not occur

Sinus Pause (Sinus Arrest)

The SA node stops (stops generating impulses)

P cells stop generating impulses
The pause (arrest) must last at least 2 seconds

Sinus Pause (Sinus Pause) and Sinus Arrest?

There is no precise match; what is the difference between sinus pause and arrest?

Sinus Pause

The SA node stops generating impulses
A substitute rhythm (junctional or ventricular) starts

Sinus Arrest

The SA node stops generating impulses
No substitute rhythm resumes
It is asystole (no QRS complexes are present)

ECG and Sinus Pause (Sinus Arrest)

On the ECG, P waves are NOT present (the SA node has stopped)

Almost always, after about 3 seconds of asystole, a junctional rhythm is activated

If sinus rhythm reactivates, then

the PP pause IS NOT a multiple of the sinus PP interval
This is the main ECG difference from 3rd degree SA block

ECG 3rd degree SA block, junctional rhythm

Sinus Pause

Junctional Rhythm
P waves are not present
Sinus pause is often indistinguishable from 3rd degree SA block according to ECG

Sinus Pause

The SA node does not generate impulses
No P waves on the ECG
The PP pause is not a multiple of the PP interval

3rd Degree SA Block
- The SA node generates impulses, but all are blocked at the T cells
- The PP pause is > 2 seconds
- No P waves on the ECG
- The PP pause is a multiple of the PP interval

Sinus Pause

At the beginning, there is a sinus contraction (with a P wave)

This is followed by a sinus pause

The PP pause IS NOT a multiple of the sinus PP interval

The SA node has stopped and later restarted (started generating impulses again)

Sinus Pause

At the beginning, there is a sinus rhythm

PP interval (720ms)

PP pause (2120ms) is not a multiple of the sinus PP interval (3 x 720 = 2160ms)

The SA node has stopped and later resumed generating impulses

Sinus Rhythm

Laddergram illustrates the propagation of impulses through the conduction system

S - P cells (SA node), S-A - T cells (Sinoatrial junction), A - atrium

In sinus rhythm, the SA node (P cells) generates impulses regularly (green dots)
Each impulse quickly reaches the T cells (S-A), where conduction slows down
Then the impulse from the T cells (S-A) travels to the atrium (A - start of the P wave)
PP interval is the same on the ECG

Sinus Pause

The SA node (P cells) generates impulses regularly (green dots)
The SA node stops and later restarts
PP pause is NOT an X-fold multiple of the sinus PP interval

Sinus Pause

PP pause IS NOT an X-fold multiple of the sinus PP interval

SA node stopped, and later restarted

Sinus Pause

Ventricular Rhythm (QRS > 0.12s)

Frequency: 25/min.
QRS has the shape of a left bundle branch block
Ectopic ventricular focus is in the right ventricle

No P waves are present
On the ECG, there is no sinus PP interval, nor a PP interval with a pause

Therefore, it could also be a Third-Degree SA Block

ECG 3rd degree sa block vs. sinus arrest, pause

Third-Degree SA Block

Initially, there are 2 sinus P waves
Then follows a pause (without P waves)
The pause is exactly 4 times the PP interval

During the pause, the SA node generates impulses

but they are blocked (no P waves are formed)

If the SA node temporarily stopped generating impulses (sinus pause)

the pause would not be a multiple of the PP interval

The pause lasts for 4 seconds, then the sinus rhythm is reactivated

Usually, after 3 seconds of asystole, a junctional rhythm is activated
If the pause were < 2 seconds (only 1 P wave was blocked)

it would be Second-Degree SA Block - Type II

Third-Degree SA Block is long-term

this is a rare ECG finding where the sinus rhythm was reactivated

Sinus Arrest

After a ventricular extrasystole, asystole occurred
The SA node has stopped (no P waves are present), and no alternative rhythm has been activated

There is no consensus on whether it is a sinus pause or sinus arrest
It could also be Third-Degree SA Block (the SA node generates impulses, but all are blocked)
Definitive diagnosis is made using electrophysiological examination

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 /

Sinus Arrest

Sinus pause, Sinus arrest

SA Node (P and T Cells)
Sinus Pause (Sinus Arrest)
ECG and Sinus Pause (Sinus Arrest)

SA Node (P and T Cells)

The SA node consists of 2 types of cells
P cells (Pacemaker cells)

Generate impulses in the SA node and determine the heart rate

T cells (Transport cells)

Transmit impulses from P cells to the atrium and internodal pathways
If the impulse does not pass through T cells, a P wave does not occur

Sinus Pause (Sinus Arrest)

The SA node stops (stops generating impulses)

P cells stop generating impulses
The pause (arrest) must last at least 2 seconds

Sinus Pause (Sinus Pause) and Sinus Arrest?

There is no precise match; what is the difference between sinus pause and arrest?

Sinus Pause

The SA node stops generating impulses
A substitute rhythm (junctional or ventricular) starts

Sinus Arrest

The SA node stops generating impulses
No substitute rhythm resumes
It is asystole (no QRS complexes are present)

ECG and Sinus Pause (Sinus Arrest)

On the ECG, P waves are NOT present (the SA node has stopped)

Almost always, after about 3 seconds of asystole, a junctional rhythm is activated

If sinus rhythm reactivates, then

the PP pause IS NOT a multiple of the sinus PP interval
This is the main ECG difference from 3rd degree SA block

Sinus Pause

Junctional Rhythm
P waves are not present
Sinus pause is often indistinguishable from 3rd degree SA block according to ECG

Sinus Pause

The SA node does not generate impulses
No P waves on the ECG
The PP pause is not a multiple of the PP interval

3rd Degree SA Block
- The SA node generates impulses, but all are blocked at the T cells
- The PP pause is > 2 seconds
- No P waves on the ECG
- The PP pause is a multiple of the PP interval

Sinus Pause

At the beginning, there is a sinus contraction (with a P wave)

This is followed by a sinus pause

The PP pause IS NOT a multiple of the sinus PP interval

The SA node has stopped and later restarted (started generating impulses again)

Sinus Pause

At the beginning, there is a sinus rhythm

PP interval (720ms)

PP pause (2120ms) is not a multiple of the sinus PP interval (3 x 720 = 2160ms)

The SA node has stopped and later resumed generating impulses

Sinus Rhythm

Laddergram illustrates the propagation of impulses through the conduction system

S - P cells (SA node), S-A - T cells (Sinoatrial junction), A - atrium

In sinus rhythm, the SA node (P cells) generates impulses regularly (green dots)
Each impulse quickly reaches the T cells (S-A), where conduction slows down
Then the impulse from the T cells (S-A) travels to the atrium (A - start of the P wave)
PP interval is the same on the ECG

Sinus Pause

The SA node (P cells) generates impulses regularly (green dots)
The SA node stops and later restarts
PP pause is NOT an X-fold multiple of the sinus PP interval

Sinus Pause

PP pause IS NOT an X-fold multiple of the sinus PP interval

SA node stopped, and later restarted

Sinus Pause

Ventricular Rhythm (QRS > 0.12s)

Frequency: 25/min.
QRS has the shape of a left bundle branch block
Ectopic ventricular focus is in the right ventricle

No P waves are present
On the ECG, there is no sinus PP interval, nor a PP interval with a pause

Therefore, it could also be a Third-Degree SA Block

Third-Degree SA Block

Initially, there are 2 sinus P waves
Then follows a pause (without P waves)
The pause is exactly 4 times the PP interval

During the pause, the SA node generates impulses

but they are blocked (no P waves are formed)

If the SA node temporarily stopped generating impulses (sinus pause)

the pause would not be a multiple of the PP interval

The pause lasts for 4 seconds, then the sinus rhythm is reactivated

Usually, after 3 seconds of asystole, a junctional rhythm is activated
If the pause were < 2 seconds (only 1 P wave was blocked)

it would be Second-Degree SA Block - Type II

Third-Degree SA Block is long-term

this is a rare ECG finding where the sinus rhythm was reactivated

Sinus Arrest

After a ventricular extrasystole, asystole occurred
The SA node has stopped (no P waves are present), and no alternative rhythm has been activated

There is no consensus on whether it is a sinus pause or sinus arrest
It could also be Third-Degree SA Block (the SA node generates impulses, but all are blocked)
Definitive diagnosis is made using electrophysiological examination

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