Category Archives: EMS12Lead.com

EMS 12-Lead: Triaging Triage ECGs

I’ve spent nine years working in an emergency department, which means I’ve also spent nine years performing electrocardiograms at triage. With a couple thousand waiting-room ECGs under my belt, I’ve noticed a few things:

  • A lot of ECGs are ordered at triage.
  • Many of them are performed on low-risk patients.
  • Very few of those ECGs lead to a change in initial management.

Oh, and one more thing:

  • Most physicians hate signing triage ECGs.

I can’t say I blame them. Triage ECGs interrupt their workflow and, worse than just slowing them down, that distraction can lead to errors. As an additional frustration, these patients often end up being seen by a different doctor in the department, and no one likes making diagnostic or treatment decisions that another provider will have to deal with. Plus, if the signing physician does happen to find something wrong, there’s always a nagging concern that the patient will end up being added to their already full group and need to be seen immediately—further interrupting flow.

Triage ECGs bring work and distraction.

So it’s understandable why many emergency physicians are rejoicing at the publication of a new study by Hughes, Lewis, Katz, and Jones: “Safety of Computer Interpretation of Normal Triage Electrocardiograms” [1].

To see a bunch of ECGs from my collection that show acute MIs but were read as normal by the computer, follow this link or click on the tracing above.

EMS 12-Lead: ECG Mixtape – Vol. 2

Welcome to the second installment in our ECG Mixtape series! It looks like this will be an irregular publication while we streamline our process of picking cases and getting permission to reproduce them. Enjoy!

Pick of the Week

This weeks top pick comes from cardiologist Dr. Gianni Manzo in São Paulo, Brazil, who shared this case on the Figure 1 app [note: the app and site require free registration to view cases].

A 78 year old male presented with a chief complaint of “oppressive” chest pain. The patient’s past cardiac history was significant for coronary artery bypass graft (CABG) surgery and pacemaker. The following ECG was obtained on arrival.

It shows an AV-sequential paced rhythm at approximately 70 bpm (probably a DDDR pacemaker). Most folks would just end their interpretation there (and the machine certainly will), but there’s a lot more to see on this tracing… like an infero-posterior STEMI!

For the rest of the discussion of this ECG, or to see the other tracings featured in our mixtape, follow this link or click on the ECG above.

EMS 12-Lead: ECG Mixtape – Vol. 1

Welcome to the start of a new series here at EMS 12-Lead. With the ECG Mixtapes we’ll compile some of the week’s best ECG’s from around the world of social media and #FOAMed. As High Fidelity taught us, “The making of a great compilation tape, like breaking up, is hard to do and takes ages longer than it may seem.” Please dig deeper into the cases that interest you.

Pick of the Week

This week’s top pick comes from Mohd Faried over at the EKG Club on Facebook.

The patient, a 58 year old female, presented with chest pain x 1 hour with diaphoresis and signs of heart failure. This ECG shows sinus tachycardia, a (presumed) new RBBB, severe ST-depression in the inferior leads, and towering ST-elevation in aVR—which add up to quite a poor prognosis. It is important not to mistake the profound ST-changes in the limb leads for an extremely wide QRS (> 240 ms); the QRS in this tracing is really about 170 ms.

For the rest of the discussion of this ECG, or to see the other tracings featured in out mixtape, follow this link or click the ECG above.

EMS 12-Lead: 59 Year Old Female – Intermittent Head Pain

One of my co-workers told me that she wants to see more case studies.

A 59-year-old female presents to the emergency department with a chief complaint of “head pain that comes and goes.”

She describes the pain as a dull ache in her occiput that’s been striking without warning a couple of times per day for the past ten days. Over the last three days she’s noted that it has also been radiating into her neck and upper back/shoulders.

Because of her vague symptoms and pain that involves her back/shoulders, a 12-lead ECG is performed soon after arrival.

For the rest of this case description please follow this link or click on the ECG above.

For the conclusion to this case you can follow this link.

EMS 12-Lead: No, doubling the paper speed will not reveal hidden P-waves

Apparently I went to the Rick Bukata School of Titling Articles.

A 22-year-old male presents with agitation and delirium after smoking an unknown substance that an equally unknown person on the street offered him. You note a rapid radial pulse at around 150 bpm and attach him to the cardiac monitor:

Figure 1. Initial rhythm at normal paper speed.

Figure 1. Initial rhythm at normal paper speed (25 mm/s).

Well now we’re in a tough spot. It’s difficult to tell whether Fig. 1 shows sinus tachycardia or some non-sinus narrow-complex tachycardia (we’ll use the colloquial shorthand of “SVT” to include all those other options on the differential, including AVNRT, AVRT, ectopic atrial tachycardia, junctional tachycardia, etc…). If it is indeed sinus tach, then the requisite P-waves must be those upright deflections in II and III and superimposed on the T-waves.

Is there something we could do to see if those really are P-waves buried in the T-waves?

If you’re like me, you were probably taught that it would be a clever move to double the paper speed in a situation like this to separate the P’s from the T’s, revealing the diagnosis of sinus tachycardia. Let’s see what happens when we do that.

For the rest of this case and discussion please follow this link or click on the rhythm strip above.

EMS 12-Lead: The 12 Rhythms of Christmas – Paroxysmal AV-Block

This article is the ninth in our latest series, The 12 Rhythms of Christmas, where we examine a different rhythm disorder with each new post. It’s a continuation of the theme behind last year’s 12 Leads of Christmas. And, just like last year’s series, I’m rather late getting the final articles out, but the end is in sight.

Hope you had a good Valentine’s Day—let’s talk about some heart stuff. Today I want to discuss a form of AV-block that many providers don’t even realize is its own unique entity: paroxysmal AV-block.

What differentiates this arrhythmia from the other AV-blocks is that it occurs in discrete, self-limited episodes—or “paroxysms.” You patient will be hanging out, minding their own business, when out of nowhere they suddenly drop two or three or forty QRS complexes in a row until the AV-node just as suddenly recovers. It tends to give you a pretty good wake-up.

Paroxysmal AV-block. Click to enlarge

For the rest of this discussion please follow this link.

EMS 12-Lead: The 12 Rhythms of Christmas – High-Grade AV-Block

This article is the eighth in our latest series, The 12 Rhythms of Christmas, where each day we examine a new rhythm disorder. It’s a continuation of the theme behind last year’s 12 Leads of Christmas.

High-grade AV-block (sometimes called advanced AV-block) is how we describe a form of pathological AV-block where two or more consecutive P-waves fail to conduct to the ventricles.

Why don’t we just call the tracing in Fig. 4 type II AV-block? Think back to the basis of our article on 2:1 AV-block: Since we never see two P-waves in a row that conduct, we cannot assess whether the PR-interval is progressively increasing (as in type I AV-block) or fixed (as in type II AV-block). You might think  that all high-grade AV-blocks must be due to a type II mechanism because the conduction defect looks so severe, but even type I AV-blocks can exhibit the sort of behavior we see above. In fact, based on subsequent tracings (not shown here), there’s a pretty decent chance both the patients whose rhythms we’re going to examine in this post were experiencing high-grade AV-block due to an underlying type I mechanism.

For the rest of this discussion please follow this link or click on the rhythm strip above.

EMS 12-Lead: The 12 Rhythms of Christmas – 2:1 AV-Block

This article is the seventh in our latest series, The 12 Rhythms of Christmas, where each day we examine a new rhythm disorder. It’s a continuation of the theme behind last year’s 12 Leads of Christmas.

Our last two posts have examined type I and type II AV-block, so it’s only fitting that we continue our theme with a topic that combines the two:

While most everyone has heard of first degree, type I, type II, and complete AV-block, comparatively few people recognize 2:1 AV-block as a valid rhythm diagnosis in its own right. That’s a shame, because 2:1 AV-block is a rather interesting finding. To understand why, consider the following dilemma:

  • Type I AV-block presents with progressively increasing PR-intervals until a P-wave is blocked

Figure 1. Increasing PR-intervals in the setting of type I AV-block. Measurements are in milliseconds.

  • Type II AV-block presents with fixed PR-intervals until a P-wave is blocked

Figure 2. Fixed PR-intervals with type II AV-block. Measurements are in milliseconds.

It should be clear from the two examples above (and the others in this series) that both forms of AV-block can present with various—and actively varying—conduction ratios: 5:4, 4:3, 3:2, etc… That doesn’t affect our ability to diagnose the rhythms, and in fact, it can be helpful to see how the PR-intervals behave with different ratios of P-waves to QRS-complexes.

  • What do you do, however, when every-other P-wave is blocked?

Figure 3. 2:1 AV-block of uncertain mechanism.

For the rest of this discussion please follow this link or click on the rhythm strips above.

EMS 12-Lead: The 12 Rhythms of Christmas – Type II AV-Block

This article is the sixth in our latest series, The 12 Rhythms of Christmas, where each day we examine a new rhythm disorder. It’s a continuation of the theme behind last year’s 12 Leads of Christmas.

Except for first degree,  type II is probably the simplest of the AV-blocks to identify. There’s really only two major criteria:

  1. A P-wave suddenly and unexpectedly fails to conduct to the ventricles.
  2. The PR-intervals of the P-waves that do conduct are fixed and equal.

Let’s examine the ECG below, which exhibits both of those findings. The computer, however, disagrees and suggests and alternate diagnosis. Which is right?

For the rest of this discussion please follow this link or click on the ECG above.

EMS 12-Lead: The 12 Rhythms of Christmas – Type I AV-Block

This article is the fifth in our latest series, The 12 Rhythms of Christmas, where each day we examine a new rhythm disorder. It’s a continuation of the theme behind last year’s 12 Leads of Christmas.

Type I AV-block is a pretty interesting phenomenon, first described in 1899 by Dutch anatomist Karel Wenckebach. It is characterized by progressive lengthening of the PR-intervals that culminates in a dropped (fully blocked) P-wave and a pause in the ventricular rhythm, reseting the AV-node so that the cycle can repeat.

Let’s look at an example:

Even those with limited experience in basic dysrhythmias should be able to identify the increasing PR-intervals…

That, however, is where most folks’ knowledge ends. But I expect most of the folks reading this blog, if they don’t already, would like to understand why this pattern occurs.

For the rest of this article please follow this link or click the rhythm strips above.