POTD: AFib in Wolff-Parkinson-White Syndrome

Atrial fibrillation can occur in up to 20% of patients with Wolff-Parkinson-White Syndrome (WPW). The accessory pathway allows for rapid conduction directly to the ventricles bypassing the AV node. Rapid ventricular rates may result in degeneration to VT or VF.

ECG features of Atrial Fibrillation in WPW are:

• Rate > 200 bpm, can be closer to nearly 300bpm!

• Irregular rhythm

• Wide QRS complexes due to abnormal ventricular depolarization via accessory pathway

• QRS Complexes change in shape and morphology

• Axis remains stable unlike Polymorphic VT

Treatment

Treatment with AV nodal blocking drugs e.g. adenosine, calcium-channel blockers, beta-blockers may increase conduction via the accessory pathway with a resultant increase in ventricular rate and possible degeneration into VT or VF

• In a hemodynamically unstable patient urgent synchronized DC cardioversion is required.

• Medical treatment options in a stable patient include procainamide, although DC cardioversion may be preferred.

Example of EKG of WPW with afib

Vtach vs Afib in WPW

Targeted Temperature Management

Targeted Temperature Management

What is it: the purposeful cooling of a patient post-cardiac arrest. Target of 32°C to 34°C (Some studies say 36, but debatable and prevent any hyperthermia) for at least 24 hours. 

Why: To improve the chance of survival and neurologic recovery, international guidelines recommend use of targeted temperature management (TTM), together with urgent coronary angiography and percutaneous coronary intervention when appropriate

Who: 

• Post cardiac arrest (any cause but most evidence supports from VF/VT shockable causes of cardiac arrest)

• ROSC < 30 mins from team arrival

• Time < 6 hours from ROSC

• Patient is comatose, GCS <8 (this is try and improve neurological outcome, so someone who is neurologically intact does NOT need TTM)

• MAP >= 65mmHg

• depends on your hospital protocol

When: Initiate within 6 hours of ROSC and maintain for 24 hours

How: 

• cold IVF at 2-3 mL/kg stat

• cooling vest and cooling machine

• sedation and paralysis

Complications:

Shivering, electrolyte abnormalities, cold diuresis, infection. 

So, for post cardiac arrest patients with depressed neurological function - Keep this in mind, but consult your ICUs and plan this patient's care together for best management. TTM needs an ICU level care admission. 

Happy Learning!

References:

https://jamanetwork.com/journals/jama/fullarticle/2645105

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4578199/
https://lifeinthefastlane.com/ccc/therapeutic-hypothermia-after-cardiac-arrest/

http://www.ijccm.org/article.asp?issn=0972-5229;year=2015;volume=19;issue=9;spage=537;epage=546;aulast=Saigal

Add Adenosine to the Flush

You have a patient in SVT, failed vagal maneuvers. Time to treat with adenosine. 

You all know this cute little three-way stop cock. Seems simple enough. That is until you need to use it... the stop and go seems somehow far more confusing than it really is.

And the one time you MUST know how to use it is to rapidly administer adenosine. You need access in the antecubital or proximal upper extremity.

Why the rush? Adenosine is rapidly metabolized by erythrocytes and vascular endothelial cells - so with its 10 second half-life, we have to administer and flush it quickly so it can reach the heart. 

Surely, there has to be an easier way! Well, folks. There is!

Make sure you have your ECG rhythm strip running, zoll pads on the patient, and explain the patient that this might "feel funny"  (as their heart stops for just a wee bit). 

• Grab a 20-mL (or 30-mL) syringe.

• Desired dose of Adenosine (6 mg or 12 mg)

• Draw up the adenosine AND the normal saline in the same 20-mL syringe.

• Administer via fast IV push

That's it! 

Adenosine is safe and maintains its effectiveness mixed with normal saline. One study even used OI access for conversion of SVT in an infant. 

Only have central access (hemodialysis port, central line)??? Per 2010 ACLS guidelines drop the dosing: 

• 1st dose: 3 mg (instead of 6)

• 2nd/3rd doses: 6 mg (instead of 12)

This lower dosing minimized risks of prolonged bradycardia. ALSO - use this lower dosing if the patient is taking dipyridamole or carbamazepine as these two medications potentiate the effects of adenosine.

REFERENCES:

J Korean Soc Emerg Med. 2003 Aug;14(3):224-227 

https://www.resus.com.au/2015/03/26/a-new-way-to-give-adenosine-in-svt/

https://www.aliem.com/2012/12/trick-of-trade-combine-adenosine-and/
Weberding NT, et al. Adenosine Administration With Stopcock Technique Delivers Lower-Than-Intended Drug Doses. Ann Emerg Med 2018;71(2):220-4.

https://acls-algorithms.com/acls-drugs/acls-and-adenosine/comment-page-2/