Adenosine in Re-Entry Tachycardias

[cfaulknor]

I was reading in a book that it is not recommended to use adenosine to treat re-entry tachycardias such as WPW or LGL syndromes. Could someone please help clarify why it is not recommended, and what the recommended treatment is (Cardiovert, CCB, etc.)

Thanks in advance for your help

[Doczilla]

Like most things, there are shades of grey here. Adenosine is okay for re-entrant tachycardias, including Wolff-Parkinson-White and Lown-Ganong-Levine, as long as the re-entrant tachycardia involves transmission (anterograde, the right way) down the AV node. WPW with a (relatively) narrow complex falls into this category, and adenosine is the drug of choice for this type of re-entrant tach. WPW that has a wide and ugly complex has a high chance of running retrograde up the AV node (this also looks a whole lot like v-tach). These rhythms have a high likelihood of having an underlying atrial fibrillation. The key here is that the AV node is still exerting some influence over the heart rate. Take out the AV node briefly with adenosine, and this sets up uncontrolled conduction across the Kent bundle of the atrial fib, leading to an even more rapid heart rate.

To simplify things when you've got a high heart rate and aren't sure if you want to give adenosine or amiodarone, go by the complex. If it's wide and ugly like v-tach, it probably is, and you should treat with amiodarone or lidocaine. Amiodarone is effective for WPW and to some extent for atrial fib, so you're not really doing a disservice to the patient if you didn't catch the WPW and thought it was v-tach. If it is a narrow complex, even with a delta wave, you're okay giving the adenosine.

And if they are unstable in any way, skip the antidysrhythmics and synchronize and cardiovert.

'zilla

[AZCEP]

You are using a wider definition than you should be on this. Adenosine is very helpful for re-entrant tachycardias, just not the ones associated with pre-excitation.

WPW and LGL use accessory pathways to conduct the atrial impulses. Most of the tachycardia management options slow conduction through the atrioventricular nodal tissue, worsening the tachycardia through the accessory pathways.

Adenosine, calcium channel blockers, beta blockers-to a lesser extent all slow conduction through the AV node. Cardioversion is the best option if it is needed. Many times you will be able to monitor the patient, and not HAVE to do anything specifically.

[cfaulknor]

My response is a bit late, but thank you all... your responses were extremely helpful