Tuesday, July 21, 2015

Emergency Transvenous Cardiac Pacing

This case was provided by one of our fine 5th year EM/IM residents, Rachael Krob MD. The description of the method for inserting a pacing wire is by one of our fine 3rd year EM residents, Mark Sandefur MD.

Case
An elderly male was found on the floor with altered mental status. When EMS arrived, he was obtunded but occasionally able to answer yes/no questions. He was found to be bradycardic in the 20's-30’s. Glucose was normal.  

A prehospital 12-lead was recorded; unfortunately, only half of it made it into the chart:
There is a slow indeterminate rhythm with a right bundle branch block morphology.  

The medics report that there was complete heart block. They gave atropine with no response, so they initiated transcutaneous pacing. They believed they had capture by palpating pulses and his mental status improved somewhat, so they had to give midazolam.  

On arrival in the ED, he continued to have altered mental status and shock, and so was intubated using RSI.

A cardiac ultrasound was performed during transcutaneous pacing.:
You can see the atrium beating at a normal rate, but the ventricle is responding very slowly.
There is normal-appearing myocardial contractility, but that the transcutaneous pacing was not capturing.  

Pacer pad placement was optimized with good anterior and posterior placement, and the amperage was turned all the way up, without capture. Because he was hypotensive and in shock, and he continued to have a heart rate in the 20-40’s, he was given 0.25 mg of push dose epinephrine, with improvement in blood pressure and heart rate. 

The decision was made to place a transcutaneous pacing wire. While this was being placed, transcutaneous pacing was discontinued due to the failure of capture and quick response to low dose IV epinephrine. A 12-lead ECG was obtained:
There is sinus tachycardia with complete (3rd degree) AV block and ventricular rate of about 50.  Notice the QRS morphology is that of RBBB and Left Anterior Fascicular Block.  
This means that the source of the escape is in the posterior fascicle.  
This is merely an interesting, though not critical, observation!
This was interpreted as bradycardia with complete heart block. While the pacing wire was being inserted, the patient received push dose epinephrine every 3-5 minutes as his heart rate and blood pressure would drift down. During this period, continuous cardiac ultrasonography showed the pacing wire in the right atrium. There was some difficulty with advancing the wire through the tricuspid valve into the right ventricle, but eventually placement was successful and appropriate capture was achieved:
 You can see the wire in the RV (see still picture with arrow in explanation below)

He was then admitted to the MICU with plans to go to the cath lab for a screw-in pacer. Outcome was good.

Placement of an Emergency Transvenous Pacer.  Ultrasound is the preferred method.

Indications (1)

I. Used for unstable bradycardia when other measures fail:
--Medical treatment is inadequate (e.g.: atropine, treatment of hyperkalemia, reperfusion for ischemia, etc.)
--External (transcutaneous) pacing fails to achieve capture, even after optimal placement and high output, or when not tolerated by the patient
--Even if transcutaneous pacing succeeds, it is usually not a good solution for multiple hours and may not be persistently efficacious.
--Often utilized in the setting of high grade AV node block, Sick Sinus Syndrome, etc.

II. Also can be used for overdrive pacing for unstable tachydysrhythmias, especially Torsades de Pointes (polymorphic VT due to long QT).

Contraindications(1)

Prosthetic tricuspid valve
Severe hypothermia
--Predisposes to VF
--Bradycardia is physiologic!

Research

Studies generally show approx 70-80% success rate.2,3
Average time to successful placement was 18 minutes.2
--30% less than 5 minutes
A 1981 study4 comparing flow directed balloon tipped catheters to standard semirigid electrode catheters revealed several important differences:
--Improved time: 6 min w/ balloon vs. 13 min w/ standard
--Fewer complications with balloon tipped catheters
Most studies assessing emergency transvenous cardiac pacing were preformed before the use of ultrasound.


Techniques

There are a couple well-described methods for this procedure:
--Sensing method
--EKG monitoring method
The main benefit of these techniques was that a physician could determine when the catheter reached the heart during the procedure without needing radiographs.

We will not discuss these techniques.

Ultrasound Technique: This is the preferred method at Hennepin County Medical Center because it is technically simpler and there are fewer opportunities for error.  It utilizes another physician or sonographer for real time ultrasound guidance. 


Place a Sheath Introducer


Right internal jugular or left subclavian veins preferred.
A Touhy-Borst Adaptor tightens around the wire, preventing leakage of blood or entry of air.

Insert the Pacing Catheter:

Roughly measure distance that will be needed.
Place a Tuohy-Borst adaptor with Cathgard on the introducer.
Insert the temporary pacing catheter into the Cathgard/sheath.
--Curvature must be directed to the left so the catheter can enter the heart:


Insert with Ultrasound Guidance:

A second provider uses ultrasound to identify the catheter entering the RV.
--Subcostal view preferred

The heart is bradycardic



Now the pacer wire is in place (see still image with arrow below) and the heart is being paced and is beating much faster.

Here is a still of the second ultrasound image:
The arrow shows the pacer wire.



Pacing Module:

An assistant connects the pacing catheter to the pacing module/box.
--Use the V ports
--Ensure correct placement of positive and negative electrodes in the module
--When the catheter is seen in the heart, turn on the pacing module.
Hit the “Emergency, Async” button, which initiates predetermined automatic settings (may vary depending on equipment):
--Asynchronized
--Rate 80
--A output 20 milliAmps (mA) (not applicable for our purposes)
--V output 25 mA



Confirm capture: ultrasound, pulse check, EKG
Adjust the rate if needed.
Tighten the Tuohy-Borst adaptor to help prevent displacement and extend the sterile sleeve.

Final Details

Obtain a CXR to confirm placement.
The pacer wire is in the RV.  Difficult to see here.  The image below shows its exact placement.
Ideal placement is in the apex of the RV.  This is not ideal, but is working perfectly.


Further Management

Discuss need for more definitive treatment with cardiology (placement of a screw-in temporary catheter, permanent pacemaker, etc).  

Temporary Pacers should be immediately replaced by more permanent ones.  Without the fixation into the myocardium with a screw (as permanent ones have), the temporary pacers can come loose and this is very dangerous!

Admit the patient to the ICU with pads in place.

References
1. Roberts JR. Roberts and Hedges’ clinical procedures in emergency medicine, 6e. Philadelphis, PA: Saunders; 2014:278.
2. Rosenberg AS, Grossman JI, Escher DJW, et al.: Bedside transvenous cardiac pacing. Am Heart J. 1969;77:697.
3. Kimball JT, Killip T: A simple bedside method for transvenous intracardiac pacing. Am Heart J. 1965;70:35.
4. Lang R, David D, Herman HO, et al.: The use of the balloon-tipped floating catheter in temporary transvenous cardiac pacing. Pacing Clin Electrophysiol. 1981;4:491.

7 comments:

  1. Hey Steve what a great write up and review. One questions though: 1. You stated you were giving push dose epi at .25mg per dose, but I always associated push dose epi using 5-20mcg per dose. Any thoughts on why the much higher doses?

    Thanks,

    ReplyDelete
    Replies
    1. Those are indeed high doses. I would have given lower doses more frequently as needed. But it worked well.

      Delete
  2. Hi there, many thanks for the cases, and your site in general! Had a very similar case to this this week- collapse, CHB, max atropine, bit of adrenaline- and like yours, transcutaneous pacing failed to capture adequately. Electrolytes all fine, pad placement changed, not acidotic- the cardio consultant that came in to put a pacing wire in said TC pacing often fails. In your experience, is there any reason for this, or is it just 'one of those things'? It was fairly alarming that what I'd previously considered a bit of a 'get out of jail free card' didn't actually get us/him out of trouble!

    ReplyDelete
    Replies
    1. George,
      I don't know how often capture is achieved, so I asked Tom Bouthillet, who knows more about it than I do. Below is what he wrote.
      Steve

      Steve:

      There is very little in the peer reviewed literature. Mostly it speaks to TCP being ineffective for asystole. However, since no one seems to know how to perform the procedure in the first place, I have my doubts about that.​ I do recall one case where bedside ultrasound was used to confirm capture. I contacted the author and asked if he had the rhythm strips and he said that he didn't. How you can publish a study about TCP and not include the ECGs is baffling. I have been interested in this topic for 15 years and I have collected many dozens of cases. I can count the cases where true electrical capture was achieved on one hand. That's why I wrote Transcutaneous Pacing (TCP) - The Problem of False Capture to bring attention to it. I think it's one of the most underappreciated problems in ACLS.

      Delete
  3. Great overview of what would need to be done for this patient. That's an interesting looking ultrasound - not unexpected, but interesting. Thanks for sharing this!

    ReplyDelete
  4. GREAT case Steve! — with Thanks to Drs. Krob & Sandefur for their assistance. Your outstanding step-by-step description with serial Echos that accurately illustrate events as they happen makes this a Textbook case worthy of bookmarking for frequent referral.

    ReplyDelete

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