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R-on-T Phenomenon

R on T phenomenon

Ventricular Extrasystole (VES)
Vulnerable Period
R-on-T Phenomenon
Defibrillator

Ventricular Extrasystole (VES)

ventricular ectopic focus depolarization

It is a spontaneous depolarization of an ectopic ventricular focus
VES commonly occur with:

Stress, coffee, alcohol, smoking...
At a frequency of approximately 10/hour

VES are usually benign and do not require treatment

Sometimes patients experience them as palpitations (heart pounding)

They are more frequent in a structurally altered heart
We recognize 3 types of extrasystoles:

Supraventricular:

Ventricular extrasystole

ECG premature ventricular complex, full compensatry pause

Ventricular Extrasystole

Sinus rhythm
Ventricular Extrasystole (VES)

Wide QRS complex (> 0.12s)
Discordance

(ST segment and T waves) are of opposite polarity compared to (QRS complex)

VES occurs earlier than the sinus QRS complex

No P wave is present

VES retrogradely spreads to the atria through the AV node

where it meets the impulse from the SA node, and the impulses are reset (refractory period)

After VES, a complete compensatory pause follows

The RR interval with VES (2 RR) is exactly twice the RR interval without VES (RR)
Because the SA node was not reset

Vulnerable Period

Latent period (LP) or Vulnerable period, period in phase 3 between ERP and RRP

Between the end of the absolute and relative refractory periods

Is the vulnerable part of the action potential

Vulnerable period

Is the most arrhythmogenic part of the action potential

Can trigger a malignant ventricular arrhythmia (ventricular fibrillation)

Lasts approximately 0.01 seconds
Occurs just before the peak of the T wave

R-on-T Phenomenon

Phenomenon R on T, malignant ventricular arrhythmia

Is a ventricular extrasystole that occurs on the T wave

Specifically during the vulnerable period

Can trigger malignant ventricular arrhythmia ONLY:

1/3 of ventricular tachycardias are triggered by the R-on-T phenomenon:

ECG sinus rhythm, Phenomenon R on T, ventricular fibrillation

R-on-T Phenomenon and Ventricular Fibrillation

R-on-T Phenomenon

A ventricular extrasystole occurs during sinus rhythm precisely at the time of the T wave

Following the extrasystole is ventricular fibrillation

Frequency: 280/min.
Wide QRS complexes (>0.12s)

ECG phenomenon R on T, and Torsades de Pointes

R-on-T Phenomenon and Torsades de Pointes

This patient had on the ECG during sinus rhythm a prolonged QT interval
Polymorphic ventricular tachycardia, which occurs with prolonged QT interval
- is called Torsades de Pointes ("twisting of the points")
The trigger for Torsades de Pointes is the R-on-T Phenomenon

Defibrillator

Defibrillator is a device that delivers an electric shock
It is used for cardioversion

Cardioversion is the restoration of normal rhythm to sinus rhythm

Synchronized cardioversion:

The device delivers an electric shock at the R wave (S wave) not during the vulnerable period
Most commonly used for treating hemodynamically stable arrhythmias:

Unsynchronized cardioversion is Defibrillation

The device delivers an electric shock independently of the cardiac cycle (regardless of the vulnerable period)
Used for urgent treatment of hemodynamically significant arrhythmias, most commonly

Defibrillator machine, paddles out shock

ECG atrial fibrillation, synchronized cardioversion with QRS

Electrical Cardioversion

During atrial fibrillation, an electrical synchronized cardioversion was performed

The device delivered an electric shock at the R wave (S wave) not during the vulnerable period

Following the electric shock, cardioversion occurred (the rhythm was restored to sinus rhythm)

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

R-on-T Phenomenon

R on T phenomenon

Ventricular Extrasystole (VES)
Vulnerable Period
R-on-T Phenomenon
Defibrillator

Ventricular Extrasystole (VES)

It is a spontaneous depolarization of an ectopic ventricular focus
VES commonly occur with:

Stress, coffee, alcohol, smoking...
At a frequency of approximately 10/hour

VES are usually benign and do not require treatment

Sometimes patients experience them as palpitations (heart pounding)

They are more frequent in a structurally altered heart
We recognize 3 types of extrasystoles:

Supraventricular:

Ventricular extrasystole

ventricular ectopic focus depolarization

ECG premature ventricular complex, full compensatry pause

Ventricular Extrasystole

Sinus rhythm
Ventricular Extrasystole (VES)

Wide QRS complex (> 0.12s)
Discordance

(ST segment and T waves) are of opposite polarity compared to (QRS complex)

VES occurs earlier than the sinus QRS complex

No P wave is present

VES retrogradely spreads to the atria through the AV node

where it meets the impulse from the SA node, and the impulses are reset (refractory period)

After VES, a complete compensatory pause follows

The RR interval with VES (2 RR) is exactly twice the RR interval without VES (RR)
Because the SA node was not reset

Vulnerable Period

Between the end of the absolute and relative refractory periods

Is the vulnerable part of the action potential

Vulnerable period

Is the most arrhythmogenic part of the action potential

Can trigger a malignant ventricular arrhythmia (ventricular fibrillation)

Lasts approximately 0.01 seconds
Occurs just before the peak of the T wave

Latent period (LP) or Vulnerable period, period in phase 3 between ERP and RRP

R-on-T Phenomenon

Is a ventricular extrasystole that occurs on the T wave

Specifically during the vulnerable period

Can trigger malignant ventricular arrhythmia ONLY:

1/3 of ventricular tachycardias are triggered by the R-on-T phenomenon:

Phenomenon R on T, malignant ventricular arrhythmia

ECG sinus rhythm, Phenomenon R on T, ventricular fibrillation

R-on-T Phenomenon and Ventricular Fibrillation

R-on-T Phenomenon

A ventricular extrasystole occurs during sinus rhythm precisely at the time of the T wave

Following the extrasystole is ventricular fibrillation

Frequency: 280/min.
Wide QRS complexes (>0.12s)

ECG phenomenon R on T, and Torsades de Pointes

R-on-T Phenomenon and Torsades de Pointes

This patient had on the ECG during sinus rhythm a prolonged QT interval
Polymorphic ventricular tachycardia, which occurs with prolonged QT interval
- is called Torsades de Pointes ("twisting of the points")
The trigger for Torsades de Pointes is the R-on-T Phenomenon

Defibrillator

Defibrillator is a device that delivers an electric shock
It is used for cardioversion

Cardioversion is the restoration of normal rhythm to sinus rhythm

Synchronized cardioversion:

The device delivers an electric shock at the R wave (S wave) not during the vulnerable period
Most commonly used for treating hemodynamically stable arrhythmias:

Unsynchronized cardioversion is Defibrillation

The device delivers an electric shock independently of the cardiac cycle (regardless of the vulnerable period)
Used for urgent treatment of hemodynamically significant arrhythmias, most commonly

ECG atrial fibrillation, synchronized cardioversion with QRS

Defibrillator machine, paddles out shock

Electrical Cardioversion

During atrial fibrillation, an electrical synchronized cardioversion was performed

The device delivered an electric shock at the R wave (S wave) not during the vulnerable period

Following the electric shock, cardioversion occurred (the rhythm was restored to sinus rhythm)

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