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58 year old male CC: chest pain

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EMS is called to the scene of a 58 year old male complaining of chest pain.

On arrival, the patient is found tripoding in a chair. He is pale, diaphoretic, and appears acutely ill. He is anxious but alert and oriented to person, place, time and event.

Onset: Pain started after carrying luggage up stairs.
Provoke: Nothing makes the pain better or worse.
Quality: Pain is described as "burning".
Radiate: Pain is across the center of his chest and poorly localized. Patient denies radiation of the pain but complains that the BP cuff is hurting his right arm, even when it's not inflated.
Severity: 9/10.
Time: About 15 minutes prior to EMS arrival.

He admits to mild dyspnea. He admits to nausea but has not vomited. No JVD sitting upright. No pedal edema.

Vital signs:

Pulse: 64
Resp: 20
BP: 199/98
SpO2: 95 on RA

Breath sounds: clear

Past medical history: dyslipidemia
Meds: Lipitor

The cardiac monitor is attached.

A 12 lead ECG is captured.

Due to equipment and/or network problems, the ECG is not able to be transmitted to the Lifenet Receiving Station for physician evaluation (a common occurrence these days). Update: No longer much of a problem with the new web-based LIFENET.

What is your impression?

How would you treat this patient?

Posted by on May 31, 2009 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , ,

Any delay in D2B time associated with increased mortality

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Rathore SS, Cutis JP, Chen J, et al. Association of door-to-balloon time and mortality in patients admitted to hospital with ST elevation myocardial infarction: a national cohort study. BMJ 2009; 339:b1807

“Any delay in primary percutaneous coronary intervention after a patient arrives at hospital is associated with higher mortality in hospital in those admitted with ST elevation myocardial infarction. Time to treatment should be as short as possible, even in centres currently providing primary percutaneous coronary intervention within 90 minutes (emphasis added).”



See heartwire coverage HERE.

And from:

Time to PCI: Is 90 Minutes Fast Enough?

“These results sound a clear warning that simply meeting the 90-minute standard isn’t good enough. Hospitals and emergency medical services systems should work together to deploy prehospital electrocardiography, activate the cath lab before arrival of patients with a prehospital electrocardiogram indicating STEMI, and establish prompt access to PCI 24/7.(emphasis added) Shaving even a few minutes off door-to-balloon time is likely to save lives!” – Kristi L. Koenig, MD, FACEP

See also:

ACC/AHA 2008 Statement on Performance Measurement and Reperfusion Therapy

Posted by on May 28, 2009 • Filed under: Uncategorized • Tagged: ,

Data quality and computerized interpretive statements

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There’s an important caveat when it comes to the GE-Marquette 12SL interpretive algorithm.

It’s highly susceptible to errors when it interprets ECGs with poor data quality.

Consider the following example.

I don’t know anything about the history or clinical presentation. For my purposes here, I’m only interested in the interpretive statements.

First, the rhythm strip.


This data quality isn’t that bad.

The rhythm is borderline sinus bradycardia with 1°AVB. The QRS complex appears to be “wide” and QRS morphology in lead II looks very much like RBBB is supposed to look like in lead I.

When I see something like this, I immediately check the leads to make sure the red and black electrodes are not switched.

Now the first 12 lead ECG.


This data quality is horrible could be improved.

I suspect this ECG was captured in the back of a moving ambulance. Note that the rhythm strip was captured at 0222 and the first 12 lead ECG was captured at 0255.

In the first place, had this been a STEMI, that’s 33 minutes of time during which the hospital could have been calling in the cath team from home (nights, weekends, holidays). This is sometimes referred to as “parallel processing” and it’s a key concept for prehospital 12 lead ECG programs and regional STEMI systems.

In addition, sometimes you will get wandering baseline artifact in the back of a moving ambulance.

All the more reason to capture your 12 lead ECG on scene with the first set of vital signs.

I cringe when I see an ECG like this on the Lifenet Receiving Station (all too often). This gives ammunition to ED physicians who don’t support prehospital 12 lead ECGs and are adamantly opposed to activating the cardiac cath lab while a STEMI patient is still in the field.

What does this ECG tell us?

In the first place, the heart rate is slower than in the rhythm strip. We also see obvious RBBB morphology in lead V1. Beyond that, the only leads we can really interpret are lead II and the right precordial leads.

The interpretive statement mentions “premature ectopic complexes with ventricular escape complexes”. It also says “lateral infarct, age undetermined.” Both of these statements should be completely ignored because of the poor data quality.

Let’s look at the third and final 12 lead ECG.


The data quality is still poor, and now we’re getting the ***ACUTE MI SUSPECTED*** message from the computer.

The GE-Marquette 12SL interpretive algorithm gets a bad rap, and those of you who have followed my blog from the beginning (or know me from the EKG Club and other internet forums) know that I have defended its capabilities from time to time.

It’s true that the computer has a high specificity when it gives the ***ACUTE MI SUSPECTED*** message, but only when it interprets an ECG with excellent data quality.

That point cannot be overemphasized.

The specificity can be improved even more if the patient’s chief complaint is chest pain and heart rate is less than 100.

The take-home point is this. If you get the ***ACUTE MI SUSPECTED*** message but your ECG is showing poor data quality, you should completely ignore the interpretive statement and capture another 12 lead ECG with excellent data quality.

Under no circumstances should you transmit an ECG with poor data quality to the emergency department for physician interpretation.

Earlier today I Googled “12 lead data quality” and found a document about the ZOLL M-series monitor called 12-Lead ECG Monitoring that says, “The 12SL analysis results can be affected by poor ECG data quality. If poor data quality is flagged by the system, the interpretation statements will be preceded by the statement, “Poor data quality, interpretation may be adversely affected.”

This feature must be unique to ZOLL, because I’ve never seen a similar message on the LP12.

How do you capture a 12 lead ECG with excellent data quality?

  • Undress the patient from the waist up, including the bra if it’s a female.
  • Prep the skin (shave the skin if necessary and use benzoin tincture if the patient is diaphoretic).
  • Strand out each lead individually and don’t wrap the ECG leads around the O2 or IV tubing.
  • If possible place your patient in a comfortable semi-Fowlers position.
  • Make sure the patient is not holding him/herself up with his/her arms.
  • Once the leads are placed, cover the patient with a sheet to prevent shivering.
  • Have the patient breathe normally.
  • Capture the ECG.

It’s really not that hard.

You should orchestrate all of this with the first set of vital signs.

You should also consider grabbing yourself a few gowns next time you’re at the hospital. The nurses will love you when you bring in a gowned patient with the ECG leads perfectly placed, an IV established, and the first set of labs drawn.

Posted by on May 23, 2009 • Filed under: Uncategorized • Tagged: , ,

Ineffective or inappropriate ICD shocks – Part III

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In Part II of this series, Medic Intern for Life left me this comment:

Our EMS Agency ran a CE course a month ago and we had a Medtronic rep warn us that not all ICDs turn off when a ring magnet is applied. Medtronic’s does but a few other makers do not.

In an effort to make sure I was giving accurate information, I contacted each of the “Big 3″ implantable medical device companies (Boston Scientific, Medtronic, St. Jude Medical) and asked each of them how their ICDs would react to ring magnet application.

Before I go further, I’d just like to say how impressed I was with the response I got from all three companies.

This was nothing like dealing with the banking, cell phone, or computer industries!

  • There were few tele-prompt menus keeping you away from live help.
  • In each case, the person who answered the phone was friendly and courteous.
  • If I needed to be transferred, I wasn’t randomly disconnected.
  • The person who transferred the call stayed on the line and introduced me.
  • The technical experts knew the products intimately.
  • Questions were answered confidently.
  • They followed up with emails.

In short, the implantable medical device industry understands customer service!

It was like dealing with Disney World!

So what did I find out?

It turns out that ring magnet application works on ICDs from all three companies, and not just Medtronic.

Here are the specifics.


Boston Scientific

When you apply a ring magnet to a Boston Scientific ICD, in most cases you will hear tones (or beeps) that correspond with the R waves on the ECG. In some cases, the device may simply beep once per second. This lets you know that you are in the right spot.

After about 30 seconds, you will hear a longer tone that indicates that tachy therapies are disabled.

At this point you remove the ring magnet.

To turn tachy therapy back on, you reverse the procedure.

If no tones are heard after you apply the ring magnet to a Boston Scientific ICD, you are either in the wrong spot, or the magnet feature has been disabled.

(Note: This feature was disabled on certain models of Boston Scientific ICDs due to an FDA Advisory.)

See also:

Using a Magnet to Temporarily Inhibit Tachy Therapy or Change Tachy Therapy to Off

CPR and External Defibrillation for Pacemaker and/or Defibrillator Patients


Medtronic

For ICDs made by Medtronic, you simply apply the ring magnet and tachy therapies are disabled as long as the ring magnet is applied. When the ring magnet is removed, tachy therapies will resume.

A technical consultant from Medtronic emailed me a document entitled “Magnet Use for Suspending Medtronic ICD Detection” (Rev B, 18-DEC-2007).

The document offers these instructions for magnet use:

  1. Locate the patient’s Medtronic ICD.
  2. Place the magnet directly over the Medtronic ICD (secure magnet to patient to prevent dislodgement from device). Leave the magnet in place for the duration of the procedure.*
  3. In this “magnet” mode, tachyarrhythmia detection and therapy is suspended and the ICD will not interpret EMI, e.g. from cautery, as an arrhythmia.
  4. If the device has Patient Alert™/ Care Alert™ Self-monitoring, you may hear a constant tone for 10-30 seconds when the magnet is first applied. If a pulsing tone or high/low alternating tone is heard with magnet application, contact the patient’s cardiologist or electrophysiologist.
  5. If a tachyarrhythmia occurs during the procedure and intervention is required, remove the magnet to restore permanently programmed detections and therapy or use external rescue. Removal of the magnet by at least two feet (61 cm) returns the device to permanently programmed operation.
  6. Magnet application does not affect the programmed bradycardia pacing mode. EMI from cautery could cause inhibition of pacing due to oversensing. If inhibition is noted on the ECG monitors, use short, intermittent and irregular bursts of cautery (e.g. less than one second in duration).
  7. Magnet removal returns the device to permanently programmed operation. Keep the magnet at least two feet (61cm) away from the implanted ICD device.
  8. Perform the following steps to ensure an electrical reset has not occurred. This can be performed on all Medtronic ICDs, except Jewel® AF 7250, Micro Jewel II™ 7223Cx, Micro Jewel® 7221 and Gem III®AT 7276.a. After 10 seconds of magnet removal, re-apply the magnet to the ICD and verify that no tone or a 10-30 second constant tone results. This indicates no electrical reset has taken place. If a pulsing tone or high/low alternating tone is heard with magnet application, an electrical reset may have occurred, then call Medtronic. b. Removal of the magnet returns the device to permanently programmed operation. Call Medtronic for sterilization instructions.* These instructions are used to disable ICDs during certain surgical procedures where EMI (electromagnetic interference) could cause the ICD to “oversense” and trigger inappropriate therapy.


St. Jude Medical

For ICDs made by St. Jude Medical, you simply apply the ring magnet and tachy therapies are disabled as long as the ring magnet is applied. When the ring magnet is removed, tachy therapies will resume.

A representative from St. Jude Medical emailed me a document entitled “Magnet Use for SJM Implanted Cardioverter-Defibrillators” (August 2008).

Interestingly, this document states:

The magnet should be positioned off-center so that the curve of the “donut” magnet is over the top or bottom end of the device as shown below. Improper magnet placement may hinder magnet activation and could lead to undesired delivered therapy.

This image appears in the document:

St. Jude Medical appears to be the only manufacturer who specifically recommends applying the ring magnet off-center.

Ask to see the patient’s ID card

As a final thought, you might consider asking the patient if s/he has an ID card for the device.

Consider this story I shared in the comments section of Part II:

We actually ran a call yesterday for a gentleman whose ICD had fired x4. He reported that he felt weak and dizzy just prior to the first shock (making us suspect the device was delivering appropriate therapy).

I asked him if he had a device ID card, and he presented one from Medtronic that identified the device as a Maximo II CRT-D.

Note: CRT-D means cardia
c resynchronization therapy defibrillator.

The card specifically stated that application of a ring magnet would inhibit the antitachycardia functions and leave the antibradycardia functions (pacing) intact.

It might be a good idea to ask to see the patient’s ID card to clarify exactly how the device will respond to application of the ring magnet.

Having said that, our protocol does not require card verification prior to applying the ring magnet, or that the ICD be a particular make or model.

If applying the ring magnet doesn’t have the desired effect, you should be in the same exact situation you were before!

See also:

Inappropriate or ineffective ICD shocks – Part I

Inappropriate or ineffective ICD shocks – Part II

Inappropriate or ineffective ICD shocks – Part III

Posted by on May 17, 2009 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , ,

Ineffective or inappropriate ICD shocks – Part II

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Discussion

Inappropriate ICD shocks are not benign events. They can have profound psychological consequences for the patient, they can trigger ventricular dysrhythmias, and perhaps most importantly, they deplete the battery life of the device.

Often, paramedics (and Medical Control Physicians) are reluctant to disable ICDs. That’s because we’re generally not experts when it comes to implantable medical devices. However, we are (or should be) experts in Advanced Cardiac Life Support.

Adding to the dilemma is the fact that supraventricular tachycardias (SVTs) good enough to fool the ICD’s detection enhancement algorithms are difficult to dismiss as benign.

Note: that’s assuming the ICD has detection enhancement algorithms, and that the detection enhancement algorithms are active! Sometimes, they are not activated until the patient has documented episodes of inappropriate ICD shocks!

Atrial fibrillation and atrial flutter are not uncommon dysrhythmias in heart failure patients. Nor are conduction abnormalities like right and left bundle branch block.

If it’s wide and fast, it’s VT until proven otherwise.

But wait… what are we told from the first day of cardiology?

Treat the patient, not the monitor.

We need to ask ourselves a couple of questions to simplify matters here.

Left to our own devices (no pun intended) would we shock a hemodynamically stable patient over and over again?

I certainly hope not.

Albert Einstein once said that the definition of insanity was doing the same thing over and over again and expecting a different result.

If a particular heart rhythm has been shocked by an ICD 8, 10, or 12 times, can we reasonably expect that something different will result from shock numbers 13? 14? 15?

Maybe the patient is hypokalemic with a prolonged QT interval and experiencing recurrent runs of Torsades de Pointes. You can shock the Torsades all you want. It’s probably going to come back until the underlying problem is corrected.

In this case, the ICD is shocking a relatively slow wide complex tachycarida that is otherwise well tolerated by the patient.

Would you shock it? If not, then you probably shouldn’t let the ICD shock it either.

Consider this algorithm cropped from:

Emergency management of arrhythmias and/or shocks in patients with implantable cardioverter defibrillators (ICDs) – A statement on behalf of the Resuscitation Council (UK), Heart Rhythm UK (formerly The British Pacing and Electrophysiology Group, BPEG), The Joint Royal Colleges Ambulance Liaison Committee (JRCALC) and the Ambulance Services Association (ASA). Resuscitation, Volume 71, Issue 3, Pages 278-282


Here’s another helpful algorithm from:

Clinical Assessment and Management of Patients With Implanted Cardioverter-Defibrillators Presenting to Nonelectrophysiologists. Circulation. 2004;110:3866-3869.


Consider this thought:

The patient has an ICD because a paramedic can’t be there 24 hours a day, 7 days a week.

If the ICD is effectively terminating episodes of VF or pulseless VT, that’s one thing. Clearly, the patient needs special treatment at the hospital and the antitachydysrhythmia functions of the device should not be disabled.

However, if the device is shocking a conscious, hemodynamically stable patient, and the rhythm is not changing after the ICD shocks, a ring magnet should be applied, and the antitachydysrhythmia functions of the device should be disabled.

If you do not disable the antitachydysrhythmia functions of the device, you could at least consider sedating your patient!

Conclusion

If you get called to a patient with an ICD that has fired, place the patient on the monitor immediately. Capture a 12 lead ECG. Hit the ‘print’ button (or assign someone to sit there with his or her finger on the print button) so you capture the pre and post-shock rhythm.

If you determine that the shock(s) are inappropriate or ineffective, and if your protocols allow it, apply a ring magnet (these can be obtained from the manufacturer) and treat the underlying cause of the dysrhythmia.

After all, you’re a paramedic! Remember?

If you need to shock the patient, remove the ring magnet. The antitachydysrhythmia functions should resume automatically.* If they don’t, tape the magnet back in place and treat according to ACLS guidelines with one modification.

If the powerplant (can) is in the upper-right chest, don’t place your pads in the standard position. Electrical current follows the path of least resistance (in this case, the leads between the tip and can, which can damage the ICD). Consider anterior-posterior pad placement instead.

Image credit: Physio-Control

Note: the device will usually be implanted in the patient’s upper-left chest, so you can use standard anterior-lateral pad placement.

In any case, follow your protocols.

* There is a caveat for devices from Boston Scientific. I will address specific procedures for ring magnet application in my next (and final) article in this series.

See also:

Inappropriate or ineffective ICD shocks – Part I

Inappropriate or ineffective ICD shocks – Part II

Inappropriate or ineffective ICD shocks – Part III

Posted by on May 8, 2009 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , ,

Paramedicine 101

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You may have noticed a new addition to my blogroll.

Paramedicine 101 is a new blog created by Adam Thompson, and it’s off to a great start!

He recently asked me and Rogue Medic to be occasional guest authors (God help him).

I just posted my first case there.

Check out: Anterior ischemia or posterior STEMI?

*** UPDATE ***

Epijunky from Pink Warm and Dry has also been added to “Team P-101″.

Welcome, Epijunky! Looking forward to blogging with you! :)

Posted by on May 8, 2009 • Filed under: Uncategorized • Tagged: ,

Ineffective or inappropriate ICD shocks – Part I

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Implantable cardioverter defibrillators (ICDs)

Once upon a time, to receive an implantable defibrillator required that you survive not one, but two episodes of sudden cardiac death. You had to have ventricular arrhythmias refractory to drug therapy, and you had to be strong enough to undergo a thoracotomy.

It’s astonishing that anyone qualified for the device!

Since then, the technology has come a long way. The device has been miniaturized, allowing a transvenous approach. The devices are also now highly programmable, and usually integrated with a pacemaker.

Thanks to a series of clinical trials (MADIT I, MADIT II, DEFINITE, SCD-HeFT) the number of patients for whom the device is indicated has grown exponentially.

Got Class II or Class III heart failure and impaired left ventricular function? Then there’s a good chance you qualify for an ICD.

What this means is that paramedics are seeing more of these devices in the field. It also means that more of our heart failure patients are going to contact 9-1-1 when they get shocked. We also may be called to a heart failure patient who presents with a wide complex tachycardia, leaving the paramedic to wonder why the ICD is not firing.

Here’s a recent case to illustrate the point.

A 70 year old male contacts 9-1-1 because his ICD has fired several times.

EMS arrives on the scene and assesses the patient.

Vital signs:

Pulse: 100 and irregular
BP: 139/79
Resp: 18
SpO2: 98 on RA

The cardiac monitor is attached.


We see a borderline wide complex tachycardia at a rate of 100 (probably paced) and a rhythm change at the end of the strip.

A 12 lead ECG is captured.


The 12 lead ECG shows a paced rhythm with concordant ST segment depression in leads V4 and V5.

As a side note, we need to remember that this patient has been shocked several times with an ICD, which could cause ST/T wave abnormalities.

This patient was shocked at least 12 more times while he was with EMS.

When I asked the treating paramedic if he captured a rhythm strip of the patient being shocked (so we could determine whether or not the device was malfunctioning) the first thing he showed me was the second 12 lead ECG.


I’m not trying to be critical here. This is an opportunity for learning. What we see in this 12 lead ECG is a loose electrode in the V2 position. Had this been an actual ICD shock, leads V1 and V3 would also have been affected. Also, the duration of the shock would have shorter.

However, the paramedic in question did document a few ICD shocks because he wisely pressed the “print” button and left the printer running.

Good call!

Here’s a rhythm strip of the ICD firing.


It shows a vertical takeoff that goes straight off the paper and comes back down to baseline after about 200 ms. (Note: it will also generally be associated with a “Yelp!”)

Here’s the post-shock rhythm.


How would you treat this patient and why?

See also:

Inappropriate or ineffective ICD shocks – Part I

Inappropriate or ineffective ICD shocks – Part II

Inappropriate or ineffective ICD shocks – Part III

Posted by on May 4, 2009 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , , ,