Effects of adenosine

  Decreases the discharge rate of sinus node.

  Decreases AV nodal conduction:
(AV) block.

  Adenosine is a strong
vasodilator, and may result in hypotension, flushing and headache.

  Strong vasodilation may result in
coronary steal effect in patients with coronary artery disease.

      Because of this, Adenosine is used to induce
pharmacological stress during myocardial perfusion

      scintigraphy.

  Bronchospasm may be seen.

 
Ultra-short acting: Half-life is < 10 seconds. Side-effects disappear quickly.

      When compared to verapamil, adenosine is safer due to its
ultra-short half-life (< 10 seconds).



The uses of Adenosine in arrhythmias

Adenosine is used for both diagnostic and therapeutic purposes in supraventricular tachycardias

involving the AV node
.

 
For therapeutic purpose

      - Adenosine can convert Supraventricular Tachycardias (
in which AV node is part of the reentry)

        to sinus rhythm.

      - Adenosine CAN NOT convert atrial flutter or atrial fibrillation to sinus rhythm.

 
For diagnostic purposes, adenosine is used

      - to differentiate Ventricular Tachycardia from wide QRS complex SupraVentricular Tachycardia.

      - to diagnose masked atrial flutter.



Diagnostic possibilities according to the response of the NARROW QRS tachycardia to
i.v. Adenosine administration


  The heart rate does not change:

      - Inadequate Adenosine dose or inadequate Adenosine delivery to the heart

      - Fascicular VT or VT of high septal origin

 
Gradual slowing and then reacceleration of the heart rate:

      - Sinus tachycardia

      - Focal atrial tachycardia

      - Nonparoxysmal junctional tachycardia

 
Sudden termination of the tachycardia:

      - AVNRT

      - AVRT

      - Sinus node re-entry

      - Focal atrial tachycardia

 
Atrial tachycardia persists but there is high grade AV block:

      - Atrial flutter

      - Atrial tachycardia



PROarrhythmic effects of the ANTIarrhythmic Adenosine

  Frequent proarrhythmic effects of Adenosine:

      - Pauses

      - Bradyarrhythmias

      - Ventricular Premature Contractions (VPCs)

      - Non-sustained ventricular tachycardia (VT)

 
Very rare proarrhythmic effects of Adenosine:

      - Sinus arrest or asystole

      - Prolonged sinus arrest and bradycardia resulting in syncope and seizures

      - During atrial flutter with 2:1 atrioventricular (AV) block, administration of Adenosine may result in

        1:1 AV conduction after a brief period of high grade AV block.

      - Sustained Torsades de Pointes

      - Ventricular flutter

      - Ventricular fibrillation




References

  2003 ACC/AHA/ESC Guidelines for the Management of Patients With Supraventricular Arrhythmias.

  2013 ESC Clinical Practice Guidelines: Stable Coronary Artery Disease (Management of).

  Circulation. 1993;87:126-134.

  Emerg Med J 2004;21:408-410.





ECG 1a. The ECG above belongs to a 14 years-old male complaining of palpitation.
Narrow QRS tachycardia with a heart rate of 165/minute is seen.

Pediatric cardiologist Dr. Mahmut Gokdemir has donated the above ECG to our website.

Click here for a more detailed ECG




ECG 1b. The ECG above was recorded immediately after i.v. administration of 10 mg Adenosine to the same patient.
Sinus rhythm with a heart rate of 82/minute is seen.

Pediatric cardiologist Dr. Mahmut Gokdemir has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 2. The ECG above is from a child with narrow QRS tachycardia. It was recorded during Adenosine infusion.
Adenosine-induced transient AV block permitted the clear observation of P waves: atrial flutter.

Pediatric cardiologist Prof. Dr. Birgul Varan has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 3. The ECG above was recorded during intravenous administration of 10 mg Adenosine to a 42 years-old man with
narrow QRS tachycardia. The
non-sustained VT attack is followed by several VPCs and a 1.5 second long pause.
Sinus rhythm is restored afterwards.

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ECG 4a. The ECG above belongs to a 60 years-old woman complaining of palpitation.
Narrow QRS tachycardia with a heart rate of 182/minute is seen.

Dr. Ahmet Uzan has donated the above ECG to our website.

Click here for a more detailed ECG




ECG 4b. The ECG above was recorded immediately after i.v. administration of 10 mg Adenosine to the same patient.
Conversion to sinus rhythm is seen.

Dr. Ahmet Uzan has donated the above ECG to our website.

Click here for a more detailed ECG





ECG 5a. The ECG above is form a 31 years-old man who was admitted to the Emergency Room with the complaint of palpitation.
Wide QRS complex tachycardia is seen. The ventricular rate is 216/minute. Is it ventricular tachycardia?
This ECG was recorded just before intravenous injection of 10 mg Adenosine.

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ECG 5b. The ECG above belongs to the same patient. It was recorded during intravenous injection of 10 mg Adenosine.
Temporary atrioventricular (AV) block during Adenosine injection reveals the underlying rhythm as atrial flutter.
The mid part of the ECG shows 4:1 AV block. As the effect of Adenosine decreases rapidly, first 3:1 then 2:1 AV block is seen.
The right side of the ECG shows atrial flutter with a 1:1 conduction.

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ECG 5c. The above ECG was recorded immediately after recording the ECG 5b.
Since Adenosine half-life is less than 10 seconds, the heart rate becomes 216/minute again.
In this case, Adenosine did not convert the arrhythmia but easily showed that the rhythm was atrial flutter.

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ECG 5d. The ECG above belongs to the same patient. It was recorded after 3 hours of i.v. Amiodarone infusion.
(The patient was offered electrical cardioversion but he refused it)
The rhythm is atrial flutter with 2:1 AV block. Saw-tooth appearence is clearly seen in leads II and aVF.

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ECG 5e. The rhythm tracing above belongs to the same patient.
It was recorded immediately after the ECG 5d, but at at a paper speed of 50 mm/second.

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ECG 6a. The ECG above belongs to a 68 years-old man with Chronic Obstructive Pulmonary Disease (COPD).
He complains of dyspnea which worsened, recently.
His ECHOcardiogram showed normal left ventricular systolic function (normal Ejection Fraction).
The narrow QRS rhythm above has a
heart rate of 123/minute.
Is it sinus tachycardia?
Do we see P waves in lead V1?
The deflections in lead V1 cannot be P waves since they do not have an acceptable PR interval.
This ECG was recorded
just before intravenous injection of 10 mg Adenosine.
The recording time is 10:09:39.

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ECG 6b. The above ECG belongs to the same patient and shows the onset of Adenosine effect.
It was recorded at 10:10:38 and shows the rhythm one minute after the ECG 6a.
Adenosine injection results in atrioventricular (AV) block and heart rate (ventricular rate) slows down.
When
heart rate (ventricular rate) slows down, flutter waves become clearly visible.
This is atrial flutter. The rhythm in ECG 6a was atrial flutter.
When you see a regular narrow QRS tachycardia with a heart rate (ventricular rate, QRS rate) of 110-130/minute
but with no clearly identifiable P waves, remember the possibility of atrial flutter.

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ECG 6c. The above ECG belongs to the same patient and shows Adenosine effect.
It is the continuation strip of ECG 6b.
Adenosine injection caused atrioventricular (AV) block and resulted in a pause of 5.4 seconds.
The rhythm is atrial flutter and flutter waves are clearly seen.

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ECG 6d. The above ECG belongs to the same patient and shows disappearance of Adenosine effect.
It was recorded at 10:10:49 (it is the continuation strip of ECG 6c).
With the disappearance of
Adenosine effect, heart rate (ventricular rate) increases again.
With the disappearance of
Adenosine effect, flutter waves become difficult to notice.

Click here for a more detailed ECG