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47 year old male: Holiday Indigestion – Conclusion

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This is the conclusion to 47 year old male: Holiday Indigestion. Thanks go to a long time reader Nicholas Eisele for this holiday case! Editor's Note: sorry for the delay, it helps to press "publish"!

When we left off, our patient was in the back of the truck with a burning sensation radiating to his back. We had run a 12-Lead ECG and our partner was wondering which facility you wanted him to drive to.

To answer that question, we should look at the 12-lead!

Frightful Weather We're Having - 3rd 12-Lead

This 12-Lead shows a normal sinus rhythm at 70 bpm without ectopy or bundle branch block. A case could be made for incomplete right bundle branch block given a QRSd of ~110ms. Strikingly we have ST-depression in I, aVL, and V1-V5 with ST-elevation in lead III. Anytime you see flat or downsloping ST-depression in aVL you should look for elevation in the inferior leads (typically III). When present, it is almost certainly an inferior wall MI.

Frightful Weather We're Having - 3rd 12-Lead - III and aVL Closeup

Many readers commented that the ST-depression in V1-V5 could be either a sign of a posterior wall MI or a "anterior ischemia". It is important to remember that ST-depression from ischemia does not localize! This concept is so important, I'm going to list it again:

ST-depression from ischemia does not localize.

Traditional evaluation of ST-depression has taught that focal ischemia may cause localized ST-depression, however, this is not the case. Subendocardial ischemia causes diffuse ST-depression and will not be found in a localized pattern. Any time you have localized ST-depression you must consider it to be a reciprocal change first!

In our case, we have ST-elevation in lead III which clinches the diagnosis of an inferior wall myocardial infarction with possible posterior extension. A subsequent ECG revealed evolving ST-elevation in the inferior leads:

Frightful Weather We're Having - 4th 12-Lead

Remember, all patients who receive one 12-Lead should at least receive a second 12-Lead! If you were not comfortable activating a STEMI from the first clean tracing, serial 12-Leads provide improved diagnostic sensitivity. A single 12-Lead may only identify ~80% of STEMI patients.

The paramedics in this case recognized this fact, activated a STEMI alert, and transported the patient to their nearest PCI center. The in-hospital ECG showed continued evolution of the IWMI with the most impressive elevation and depression of the patient's clinical course:

Frightful Weather We're Having - In-Hospital 12-Lead

They achieved an impressive 83 minute first medical contact to balloon time with one stent placed in the RCA.

Frightful Weather We're Having - Cath Pictures

We hope you've enjoyed this case as much as we did, but more importantly this case presents some great teaching points:

  • Sometimes STEMI patients will have atypical symptoms.
  • A single ECG is not enough to detect all STEMI patients, serial 12-Lead ECG's should be acquired on all patients who receive one.
  • ST-depression from ischemia does not localize, localized ST-depression should be considered a reciprocal change until proven otherwise.

47 year old male: Holiday Indigestion

18 comments

Thanks go to a long time reader Nicholas Eisele for this holiday case! As always, details have been changed to protect patient privacy.

It is a blustery Christmas morning when you and your partner are dispatched for a 47 year old male with chest pain. Firefighters are already on scene obtaining a history and vitals when you arrive.

You check in with the officer in charge, a paramedic, and he reports that the patient has been having a "burning sensation" in the middle of his chest, going to his back. As it is Christmas morning and the patient's family is opening presents, the officer also relays the patient, "is likely going to refuse." He also relays that they witheld ASA due to the patient's "indigestion."

One of the firefighters gives your partner the patient's vitals:

  • HR: 70 bpm, regular at the radials
  • BP: 144/96
  • RR: 18, unlabored, in no apparent distress
  • SpO2: 95%
  • ECG: "normal sinus, nothing out of the ordinary" (no 12-Lead was captured)

You perform a quick patient assessment prior to making any decisions:

  • Onset: 21:00 the prior evening
  • Provocation/Palliation: pain went away over night with sleep, came back after breakfast; nothing makes it better now
  • Quality: "burning"
  • Radiation: "straight thru to my back"
  • Severity: 7 of 10
  • Timing: constant burning

A focused history reveals no prior cardiac problems and that the patient takes no medications and has no allergies.

Given the patient's symptoms and possibility of a true cardiac problem you advise the patient that a trip to the hospital is worth it just to make sure he's not experiencing something serious.

After he sits down on your stretcher your partner begins placing electrodes for a 12-Lead as you gather four baby aspirin for the patient to chew.

Frightful Weather We're Having - Initial 12-Lead

You notice the artifact and hit print again, however, you decide you can run another one in the truck. After loading the patient your partner hands you the second 12-Lead, which is a bit cleaner than the first.

Frightful Weather We're Having - 2nd 12-Lead

Not completely satisfied, you run a 3rd 12-Lead in the back of the truck.

Frightful Weather We're Having - 3rd 12-Lead

Your partner asks which facility you'd like to go to.

  • What do these 12-Lead's show?
  • What are your next steps?
  • Is indigestion a contraindication to aspirin administration?
  • Are you glad this case does not involve a narrow complex tachycardia?

59 Year Old Male–”Lifting Boxes”: Part II, with a twist!

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This is part II to 59 year old male–"Lifting Boxes". You may wish to review the case.

Let's review the ECG:

There is sinus rhythm at about 90 bpm. Some of you saw a slight bit of ST elevation in the inferior leads, and maybe an abnormal aVL. Perhaps? Perhaps not? V1-V4 look possibly abnormal, but there is an awful lot of artifact. There appears to be a bit of ST depression in V5-V6. Is this an ischemic ECG? Looks concerning from what we can decipher.

Sometimes on blog posts, we get used to crisp ECGs and tidy scenarios. Nothing wrong with that. Sometimes, though, our cases on the street just don't go like that. Often there is much to learn from those, but I digress.

 There are a couple of real concerns with this case;

  • As correctly pointed out in the comments, the quality of the ECG is poor. This leads to all sorts of interpretation problems. If we put effort into it, we can usually get a pretty good tracing. On occasion though, it can be tough.
  • Another issue is that the 12 lead was not acquired early on. The crew acquired the ECG in the ambulance after the following: assessment, history, physical exam, O2, ASA, bathroom break, change of clothes, etc. This is not what we are after, and we could miss important findings by waiting this long.

As most of the comments reflect, the timing of the ECG and poor quality make it tough to interpret, and tough to activate the cath lab. I know some of you saw findings that led to you say you would activate, but doing so based on this one poor quality ECG is tough to do. Just is. 

So off to the community hospital he went. 

Calls are run like this every day. We all know it. In fact, it is one of the reasons we discuss cases such as this.

Could this patient have benefited if the call was handled differently? 

Fortunately, we know that he did!

In a contrasting plot twist, this call was actually handled quite differently:

In reality the crew obtained the history and vitals previously mentioned. However, undaunted by the patient's reluctance they convinced him to allow a 12 lead to be acquired immediately. This is what they found:

Due to the patients girth and breathing patterns, it was difficult for the crew to acquire a totally clean ECG. However, this one clearly shows ST elevation inferiorly, as well as V5 and V6. We can also see ST depression in V2-V4 with tall R waves. There is also slight ST depression in aVL: Infero-postero-lateral STEMI. 

The crew acquired another 12 lead with V4R which revealed about 1mm of ST depression in V4R:

The ECGs were transmitted, and the patient was emergently transported to the cath lab, where he underwent PCI and had a successful outcome.

For comparison, note how much the ST segments resolved from the first 12 lead to the one acquired in the ambulance:

After just a short period of time from the first ECG,  obvious ST elevation in II and III has mostly resolved. Timing is everything!

The point of all of this is to clearly illustrate the importance of early 12 leads and good data quality. The prehospital care of this patient could have gone either way. We see it every day. How we handle those first minutes, and the quality of the data we acquire will have a huge impact on the care our patients receive.

What are your thoughts? I'm sure you have experiences similar to this one!

 

 

Comparing 12-Leads: Discussion

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This is the discussion for Comparing 12-Leads: Common Error or Common Disease? All of our readers were on the right track, and many were spot on!

Sometimes, troubleshooting an ECG is more than just lead placement. In this case report, we had three 12-Lead ECG's, all featuring a similar pattern: inappropriate R-wave progression.

You Take the Lead - Inappropriate R-wave Progression

Initially, when reviewing the first of these ECG's, I had believed it to be lead placement error. The most likely cause of inappropriate R-wave progression and low voltage in a precordial lead is the placement of the electrode on the mammary tissue or on the abdomen.

After reviewing two more ECG's from two different shifts, it became evident that the problem was more likely with the equipment than operator.

Two of the paramedics on duty were alerted to the possibility of a malfunctioning cardiac monitor, and the same was taken out of service for testing. During their investigation, it was found that the cables themselves were at fault.

The following is a 12-lead ECG acquired from one of the Paramedics using the current set of malfunctioning LP15 cables:

You Take the Lead - 12-Lead Comparison: Bad Cables

A set of LP12 cables was then connected to the same Paramedic and then connected to the same cardiac monitor:

You Take the Lead - 12-Lead Comparison: Good Cables

The difference in these 12-Lead ECG's is striking.

Remember, R-waves should progress in a continuous fashion from V1 through V6. Usually with a transition from negative to positive around leads V3 and V4. This is known as good R-wave progression.

R-Wave Progression - The Textbook of Medical Physiology 9e; © 1996 Guyton AC, Hall JE; WB Saunders.

With Paced Rhythms, RBBB, LBBB, RVH, LVH, or myocardial infarctions this zone of transition and R-wave progression may be early or delayed. You'll often hear about poor R-wave progression or an early or late transition. These refer to the change in dominant polarity across the precordial leads, whether from positive to negative or vice versa.

In any case, the changes must be continuous. Any discontinuity indicates a problem in acquisition.

Whenever you review a 12-Lead, be sure to consider the validity of the tracing beyond simple interpretation. You should be checking for baseline wander, excessive artifact, and electrode placement.

  • What types of machine failures have you seen that have gone unnoticed?
  • Do you have a QA program in place to assess the quality and accuracy of 12-Lead ECG acquisition?
  • Does your department discuss data quality issues during training?

See also:

Precordial Leads – The Transition, R-Wave Progression, R/S Ratio in Lead V1

50 year old male CC: Chest Pressure – Discussion

9 comments

This is the discussion for 50 year old male CC: Chest Pressure.

We could not have been happier at the number of insightful comments we received on this case! Many of you caught on to our purpose for this case as we could not have picked a better borderline example!

When we last left our crew they were preparing to transport a 50 year old male who appeared acutely ill. Their first 12-Lead ECG suffered from excessive baseline wander, but appeared to have some ST-elevation present. Attempts were made at improving the quality of the tracings with little success.

Here is the initial 12-Lead ECG, this time with the computerized interpretation included:

This 12-Lead ECG shows marked baseline wander, sinus bradycardia, ST-elevation of at least 1 mm in II, aVF, and V4-V6 with ST-depression in leads aVR and V1. The monitor's algorithm believes the ST-changes are the result of Early Repolarization.

They attempted to troubleshoot the baseline wander with patient coaching, and after two more attempts they captured the following 12-Lead ECG; again with the computerized interpretation included:

This 12-Lead ECG also shows marked baseline wander, a sinus rhythm, ST-elevation of at least 1 mm in II, aVF, and V4-V6 with ST-depression in leads aVR and V1. In this tracing, just 2 minutes later, the monitor's interpretation has changed to read the ominous *** ACUTE MI SUSPECTED *** message, suggesting an inferiolateral infarct pattern.

Between these two 12-Lead ECGs we can clearly see that ST-elevation is present in leads II, aVF, and V4-V6 with ST-depression clearly visible in aVR and V1. It is difficult to tell with the baseline wander whether any PR-segment changes exist or if the J-point in aVL is depressed.

At this point our differentials should include:

  • Acute inferiolateral myocardial infarction
  • Pericarditis
  • Early repolarization

Given our patient's recent history of strep throat, diffuse ST-elevation, concave-up T-waves, and ST-depression in aVR and V1 we should strongly consider pericarditis. The baseline wander present makes accurate evalution of the PR-segment difficult, but a case could be made for PR-elevation in aVR. Compare our tracings with the discussion to 39 year old male CC: "Sick".

However, given the presentation of typical MI symptoms and a borderline ECG (albeit without reciprocal changes), we have no conclusive means of ruling out an inferiolateral myocardial infarction. If your service area has the ability to, it would be beneficial to transmit these borderline ECGs to a receiving facility for a second opinion. Compare our tracings with the discussion to 77 year old female CC: Chest Pain.

Our crew found themselves in quite the pickle!

In these instances it is prudent to err on the side of the patient and treat this as a STEMI, which is exactly what the crew did.

Upon arrival at the PCI center the following ECG was acquired:

The ED 12-Lead shows a normal sinus rhythm without ectopy. ST-elevation of at least 1 mm exists in leads II, aVF, and V4-V6. ST-depression is present in lead aVR. The monitor's interpretation is unknown.

The ED physician concurred with the activation and the patient was sent for an emergent cardiac catheterization.

No culprit lesion was found and the crew was later informed the patient was being treated for pericarditis.

This case represents a false positive, however, it is the author's opinion that this case does not represent an inappropriate field activation due to the borderline field ECG.

Some clues on the 12-Leads that favor pericarditis include a lack of reciprocal ST-depression in aVL, a normal QTc, concave-up ST-segments, and ST-depression in aVR and V1. When available echocardiography could be utilized to look for wall motion abnormalities prior to sending this patient to the cath lab.

When designing a STEMI system to provide maximal benefit to the patient a certain false positive rate is to be expected. The system must recognize the existence of this gray area and allow for overtriage in order to be successful for both the patients and their providers.

  • What are your thoughts on the conclusion to this case?
  • How many attempts at acquiring a clean tracing should be made?
  • If your system allows Paramedic activation of STEMI, are you provided constructive feedback?

50 year old male CC: Chest Pressure

40 comments

We hope you enjoy this case, as always some details have been changed to protect patient privacy.

It's around 05:00 when the tones go off at your fire station for a medical response at a large apartment complex.

You leave the bunkhouse with the engine crew and check enroute. Dispatch relays you are headed to a 50 year old male with chest pain.

Upon your arrival to a first floor unit, you find the door unlocked and the patient sitting in a chair in his living room. He appears anxious, is pale and is holding his chest. The engine crew begins obtaining vital signs and places the patient on the cardiac monitor.

The patient tells you he was awoken from sleep with "some really bad pressure". He'd had the same pain, "come and go yesterday," and that he saw his doctor and was diagnosed with "strep throat".

When you ask about any other history he says he only has high blood pressure and high cholesterol, but denies taking any medications at all. 

  • Pulse: 56, strong and regular
  • BP: 136/94
  • Resps: 22, labored
  • SpO2: 96%
  • Skin: pale, clammy

The patient is placed on a nasal cannula at 4 L/min.

You perform a focused assessment of the patient's chest pain:

  • Onset: yesterday
  • Provocation/palliation: nothing makes it better or worse, not reproducible upon palpation
  • Quality: "Pressure"
  • Radiation: localized retrosternal, does not move
  • Severity: 8 of 10
  • Timing: "went away 8 hours ago, woke me up so I called 911."

One of the firefighters hands you the 3-Lead as your partner is placing the electrodes on for a 12-Lead.

The patient denies any medication allergies and is handed 324 mg of chewable aspirin. Your partner hands you the 12-Lead.

Due to the wandering baseline you ask your partner to work on a cleaner tracing. The patient is instructed to breath slowly and to stay still. After the second attempt your partner hands you the following 12-Lead.

The patient states he feels very nauseous.

You're 10 minutes from the nearest hospital, 15 minutes from the nearest PCI center, and your patient has been to them both.

  • What do you think is wrong with the patient?
  • Is the recent diagnosis of "strep throat" important?
  • Should this patient go to the PCI center or to the community hospital?
  • How would you continue treating this patient?

 

64 year old male CC: Indigestion – Discussion

11 comments

This is the discussion to 64 year old male CC: Indigestion.

If you recall, we had a stubborn gentleman complaining of indigestion with a significant cardiac history. Considering the symptoms kept our patient awake, are highly suggestive of a coronary event, and we have uncompensated hypotension, we should have a keen interest on any ECG findings.

The rhythm appears to be regular, sinus in origin, rate of ~70 bpm, without ectopy. There is a fixed PR-interval of 0.2 s and a 1:1 association of P-waves to QRS complexes. The QRS is wide at 0.18 s, likely due to a bundle branch block. Normal sinus rhythm with a bundle branch block.

Evaluating the QRS complex in V1, we see it is wide and V1-positive confirming our suspicion of a bundle branch block. However, given the changes in leads I and V6, it is not a classic Right Bundle Branch Block. Instead we have a non-specific intraventricular conduction defect, or IVCD. A right axis deviation is present.

Looking at the contiugous lead groups:

  • Inferior: pathologic Q-waves present, isoelectric ST-segments, non-specific T-wave abnormalities
  • Septal: baseline wander, minimal ST-depression in V1-V2 (potentially attributed to the baseline)
  • Anterior: pathologic Q-wave in V4, isoelectric ST-segments, non-specific ST-T-wave abnormalities
  • Lateral: pathologic Q-wave in V5-V6, isoelectric ST-segments, non-specific ST-T-wave abnormalities
  • High-Lateral: unremarkable outside of underlying conduction defect
  • aVR: unremarkable outside of underlying conduction defect

Pathologic Q-waves in the inferiolateral lead groups are consistent with our patient's history of multiple prior MI's, however, without a prior ECG it is tough to determine if these are not from a recent myocardial infarction.

The potential ST-depression in the septal leads may be reciprocal changes in the setting of a posterior MI. The patient's skin condition made acquisition difficult, but coupled with the patient's signs and symptoms it would be prudent to explore this possibility. Attempts could be made at the acquisition of a posterior view.

The interventricular conduction defect present may be an acute finding or it may be a baseline finding. Given the QRSd is around 0.18 s there is a non-trivial defect present. Without access to the patient's prior ECG's we are unable to determine its significance.

While examination of the 12-Lead ECG for this patient did not yield any acute findings, in conjunction with our patient assessment we have enough to form a differential diagnosis:

  • Acute myocardial infarction
  • Recent myocardial infarction
  • Congestive heart failure
  • Pulmonary embolism (albiet less likely due to symptoms)

However, any differential diagnosis for this patient is rendered moot by his stubborn desire to refuse transport!

The paramedics on this call rolled up their sleeves and got to work convincing this gentleman that his signs and symptoms were anything but normal. He begrudingly sat on the stretcher and consented to transport.

They placed him on O2 by nasal cannula, obtained IV access, administered a fluid bolus, and transmitted the 12-Lead ECG to a local STEMI receiving center. His blood pressure improved enough with fluid administration to allow nitroglycerin, which the patient said improved his discomfort.

Transmission of the patient's ECG was key in this case as the receiving facility determined acute changes were present.

The patient was taken directly to the cath lab where a 90% occlusion of the LAD, just proximal to a previous stent, was found. The lesion was ballooned and stented, and the patient was admitted to the CCU for recovery.

Some additional questions for discussion:

  • Why was this patient's hypotension uncompensated?
  • Are there any differentials we missed?
  • Why was indigestion left off the list of differentials?

64 year old male CC: Indigestion

20 comments

One of our faithful readers, Nicholas Eisele, sent in this interesting case study. As always, changes have been made to protect patient confidentiality.

After a long night of car wrecks, you get dispatched right before shift change on a Sick Person call.

As you arrive, your partner states she may have been here once or twice, usually for chest pain. A woman is waiting for you outside.

You meet the patient's wife on the porch and she leads you inside to her husband, sitting in a recliner, holding his chest. He appears to be in mild distress with moist, pale skin. As you kneel beside him to begin your assessment he speaks up.

"I said don't call the ambulance, it is just indigestion."

Deftly you obtain a history while your partner grabs a set of vitals.

  • Bypass x 5
  • Stent placement, "last Christmas"
  • Hypertension
  • Hypercholesterolemia
  • Type 2 Diabetes

You nod your head while the patient explains his reluctance, "to miss a good tee time this morning". You coax a medication list from him as well.

  • Lisinopril
  • Metoprolol
  • Metformin
  • NitroTabs

His wife adds that he was up all night and vomited more than once. She also informs you he has, "serious morphine and PCN allergies."

Your partner taps you on the leg before she quickly runs down the vitals.

  • Weak radials, "barely palpable"
  • Pulse: 80, regular
  • BP: 88/46
  • RR: 24
  • SaO2: 95% on room air

The cardiac monitor is attached.

The patient remains adamant that he does not need to go to the hospital. However, he consents to a 12-Lead ECG.

Due to his diaphoresis, it takes multiple attempts to acquire a readable ECG.

What is the rhythm?

What does the 12-Lead show?

Should this patient be allowed to refuse?

54 year old female CC: BLS intercept – Conclusion

8 comments

This is the conclusion to 54 year old female CC: BLS intercept.

I did not expect to get so many comments! Great discussion on many points. It even afforded an opportunity to review atrioventricular blocks.

Going back to the case let’s look at the initial 12-Lead ECG.

First 12-Lead

As many readers noted, there is a lot of baseline wander. This is not the most helpful of 12-Leads. On scene the crew attempted multiple 12-Leads, however, the patient would not sit still and that was the best one.

I think a close look at the Initial 12-Lead has enough information to make a field diagnosis.

Leads III and aVF have subtle ST-elevation and Q-waves, which without any cardiac history are likely new. More importantly, the ST-elevation in III and aVF is proportionately large compared to the QRS amplitude. Leads aVL, V2, and V3 all have at least 1mm of ST-depression without question. I’ve borrowed Tom’s technique of using PowerPoint to stretch the leads vertically while preserving the ST/QRS ratio to help illustrate these findings.

Leads III, aVF, aVL, V2, and V3 stretched vertically

Is ST-elevation present in two or more contiguous leads?

Yes.

Additionally, we should take into account all of our findings which strongly suggest an MI.

  • Chest pain which awoke the patient from sleep
  • Left sided paresthesia
  • ST-elevation in two contiguous leads, with reciprocal changes
  • 3° AV Block, with a junctional escape
  • Hypotension

This constellation of findings would be expected with an occlusion of the RCA, potentially with right ventricular and/or posterior involvement. We can solidify our hunch with knowledge that the AV node is fed by the RCA in right-dominant individuals. ST-elevation in Lead III > Lead II is suggestive of RCA occlusion.

The crew in this case activated the cath lab from the field. They gave 324 mg ASA, started bilateral lines, gave multiple fluid boluses, placed pads for pacing, and administered 0.5 mg atropine while preparing the patient for transcutaneous pacing.

At the receiving facility, after they switched to the ED’s monitor, the patient’s rhythm changed to a 2° AV Block Type II with a ventricular rate of 70, easily palpable radials, and improved skin color.

In the cath lab, the following was found:

100% Occlusion Mid-RCA

100% mid-RCA.

Successful reperfusion

Successful reperfusion.

Diagnosis: Acute ST-elevation myocardial infarction.

66 year old female CC: Chest pressure – Conclusion

1 comment

This is the conclusion to 66 year old female CC: Chest pressure.

Let’s take another look at the 12-lead ECG.

Let’s break this down 3 leads at a time starting with leads I, II and III.

When you have artifact in a particular cardiac cycle you need to make a conscious effort not to let it influence your interpretation. So let’s look at this again with the second cardiac cycle removed.

Now we can see that ST-elevation is present in leads I, II and III. This would be unusual, but not impossible, for acute STEMI. However, pericarditis has to be a part of our differential diagnosis.

I’m always suspicious of pericarditis when I see ST-elevation in leads I and II. In addition, there is a “notched” J-point in lead I. However, the ST-segment is straight (non-concave) in leads II and III.

Now let’s look at leads aVR, aVL and aVF.

Again we need to make a decision as to which cardiac cycle we “trust”. I’m using the second cardiac cycle in my analysis.

There is a notched J-point in lead aVL but no ST-elevation (and it must be said, no reciprocal change in lead aVL which is almost always present with acute inferior STEMI). Lead III shows non-concave ST-elevation which favors acute STEMI.

Now let’s examine the right precordial leads V1, V2 and V3.

If you take nothing else away from this post, commit this ECG pattern to memory! This is highly suspicious for the reciprocal changes of acute posterior STEMI! The R/S ratio is > 1 in lead V2 (increased R-wave amplitude) and we have > 1 mm ST-depression in leads V1-V3.

Garcia and Holtz call these “carousel ponies”. Imagine the R-wave is a pole and the ST-depression is the saddle. This is an important 12-lead ECG finding and one that must be taken seriously.

If this was the ONLY abnormal finding on this ECG I would call it a STEMI (assuming clinical correlation). But, I would capture modified posterior leads V7-V9 just to have an ECG in my hand that showed the STEMI. Otherwise, there is a chance the patient’s reperfusion would be delayed by a well-meaning clinician who decided it was NSTEMI and not STEMI.

Finally, let’s look at the left precordial leads V4, V5 and V6.

The poor data quality here is unfortunate, because leads V5 and V6 probably show > 1 mm of ST-elevation here (which meet the conventional STEMI criteria). It can’t be stressed often enough. It’s critically important to obtain a clean tracing on a chest pain patient.

In this case, it all worked out well. The paramedics and the emergency physician agreed that it was an acute STEMI and the cardiac cath lab was activated.

Angiography revealed 100% occlusion of the obtuse marginal (major branch of the left circumflex). The lesion was crossed with a wire, the balloon was inflated, and a stent was successfully placed with successful reperfusion.

This ECG reminded me a little bit of the second ECG from 66 year old male CC: Chest pain (at least in the precordial leads).

63 year old male CC: Syncope – Conclusion

5 comments

Here is the conlcusion to 63 year old male CC: Syncope.

First, let’s take another look at the 12-lead ECG.

This 12-lead ECG shows poor data quality.

This is a problem because the ECG is abnormal and suspicious for acute anterior STEMI.

We need to consider whether or not this could be benign early repolarization or a strain pattern from left ventricular hypertrophy.

This ECG does not meet the voltage criteria for LVH and does not have the general appearance of a “strain pattern” (but it would be nice to be able to take a nuanced look at the ST-segments and T-waves in leads I and aVL).

Could it be benign early repolarization?

Stephen Smith MD from Dr. Smith’s ECG Blog has come up with two different decision rules to help distinguish acute anterior STEMI from benign early repolarization.

Here they are in Dr. Smith’s own words:

Decision rule #1

If the mean R-wave amplitude from V2-V4 is less than 5 mm, then it is almost certainly MI. If greater than 5 mm, it is probably BER. A cutoff of 5 mm gives a sensitivity for MI of about 70%, but a specificity of greater than 95%.

In this case the first decision rule favors BER.

Decision rule #2

If 2 of the following 3 questions are answered “yes”, then it is MI with an accuracy of about 85%: 1) is the QTc > 392 ms? 2) Is the ST elevation at 60 ms after the J-point in lead V4 > 2mm? 3) Is the R-wave in V4 < 13 mm?

In this case the second decision rule favors acute anterior STEMI.

Do you see why this is such a difficult case?

I’ve said it before and I’ll say it again.

Sometimes the “go or no go” decision for the cardiac cath lab comes down to fractions of millimeters!

I really liked the way Tim Phalen explained the importance of serial 12-lead ECGs when we appeared together on the MedicCast at EMS Today 2010. He compared it to taking a single photograph of Old Faithful.

“Maybe it’s a geyser. Maybe it’s a hole in the ground.”

In this case a single 12-lead ECG was captured by the EMS crew. They did, however, obtain another rhythm strip as they were pulling into the hospital.

It appears as though this might show a change from the initial rhythm strip but we’re in monitor mode and a diagnostic quality 12-lead ECG should be used to observe changes on serial ECGs.

Let’s move on because poor data quality is about to rear its ugly head again. This time inside the hospital.

Here is the 12-lead ECG captured on arrival at the hospital.

Now we have a 12-lead ECG with excellent data quality.

When the medical chart was pulled it was discovered that the patient had a history of “remote inferior wall myocardial infarction”.

It was the next ECG that led to the patient becoming a “Code STEMI”.

You will note that someone has drawn brackets around the ST-segments in leads II and III.

This problem is, this isn’t ST-depression. This is artifact.

The ST-depression is not present in the first cardiac cycle. In addition, the baseline is shifted upwardly prior to the P-wave, marking this as some kind of wandering baseline or loose lead artifact.

Poor data quality continues in the right precordial leads.

From the cath report:

“The initial ECG in the emergency department was of concern because of ST-elevation in the anterior septal leads. This was not clear-cut acute myocardial injury-type ST-elevation. A follow-up ECG revealed the same findings and also non-specific inferior T-wave changes, possibly representing reciprocal changes. These changes were different in comparison with the previous ECG from our office in 2004. Therefore, ER physician’s consultation with me, we elected to treat this as a Code STEMI event.”

The patient was sent to the cardiac cath lab where angiography revealed no acute lesions.

Serial cardiac biomarkers came back negative.

The patient ruled out for acute myocardial infarction.

Please don’t think that I believe I’m perfect. I know that I’m not. All human beings make mistakes and that’s why patient safety experts like Peter Pronovost advocate designing systems that help minimize the impact of human error.

The first 12-lead ECG captured in the emergency department might have been reason enough to cath this patient (I am not in possession of the 12-lead ECG from 2004 so it’s difficult to speculate).

I also know that emergency physicians are under tremendous pressure not to delay care for acute STEMI patients.

It is impossible to identify acute STEMI with perfect sensitivity and specificity.

Having said that, poor data quality should not enter into the equation.

72 year old male CC: “Unknown problem” – Conclusion

10 comments

Here is the conclusion to 72 year old male CC: Unknown problem (man down)

Here was the initial 12-lead ECG.

 

Based on this ECG the lead paramedic called a "STEMI Alert" and transmitted the ECG to the receiving hospital.

The on-duty ED physician received the ECG and the paramedic's radio report.

The ED physician called up the patient's records on the computer system. It turned out that the patient had been to the hospital before.

There was a copy of a prehospital 12-lead ECG from March 2009 on file in the patient's chart.

 

Based on the similarities between this ECG and the ECG recorded on this call (and the fact that the presentation did not exactly scream ACS) the ED physician did not call the "Code STEMI" while EMS was still in the field.

It would prove to be the correct decision.

This is the 12-lead ECG that was captured on arrival.

 

You will note that this ECG is very similar to the prehospital 12-lead ECG captured back in March 2009. However, it's slightly different from the prehospital 12-lead ECG taken earlier that evening.

Go back up and look at the prehospital 12-lead ECG.

The frontal plane axis is off by about 15 degrees, the T-wave inversion in lead aVL is more subtle, and the R/S ratio in lead V2 is > 1.

Since these findings are not present in the 12-lead ECG taken on arrival at the hospital, it can probably be explained by lead placement.

Paramedics often project that attitude that skin prep and electrode placement are a low priority, but this case demonstrates why it's essential to quality patient care.

With careful lead placement and excellent data quality, the GE-Marquette 12SL interpretive algorithm does not give the ***ACUTE MI SUSPECTED*** message.

In addition, the ST-depression / inverted T-wave was a critical finding on the prehospital 12-lead ECG, because it suggested the possibility of a reciprocal change to the spurious ST-elevation in lead III.

The presence of the inverted T-wave on the "old" ECG made the ED physician take this finding with a grain of salt.

There's nothing wrong with having multiples sets of "critical eyes" looking at an ECG prior to calling in the cavalry, especially for a marginal ECG where it's questionable as to whether or not the "1 mm of ST-segment elevation in 2 or more anatomically contiguous leads" criterion is met.

That's how we minimize false positives, control health care costs, and do the right thing for the patient.

So we're 0 for 1 with our STEMI Alert protocol. However, on this particular day, the system demonstrated a hidden strength! The STEMI Alert allowed for a quick comparison to an "old" ECG.

72 year old male CC: “Unknown problem”

22 comments

EMS is dispatched to a 72 year old male patient. Third party call. History of Parkinson's Disease. Patient is conscious. No further information.

On arrival, EMS finds a 72 year old Spanish-speaking male. Through an interpreter the lead paramedic determines that the patient became dizzy, fell down, and hit his head. A small hematoma is visible above the patient's right eye.

The patient is awake but somnolent. He is oriented to person, place, time, and event. The remainder of the neurological exam was normal.

Since the patient is not alert the crew applies manual C-spine stabilization and continues the exam.

The patient denies chest pain or shortness of breath.

Breath sounds are clear bilaterally.

The patient denies any significant medical history and states that he takes no medications.

Vital signs are assessed.

  • Resp: 18
  • Pulse: 80
  • BP: 104/70
  • SpO2: 98 on RA

The cardiac monitor is attached.

 
A 12-lead ECG is captured.
 
 
The lead paramedic notes that the arm leads are reversed. The problem is corrected and another 12-lead ECG is captured.
 
 
The black electrode is replaced and a third 12-lead ECG is captured.
 
 
What is your impression and what would you do next?
 

*** UPDATE ***

 

 
In the first graphic you can see that it's debatable as to whether or not 1 mm of ST-segment elevation is actually present in the 12-lead ECG when you use the TP segment as the baseline.

The first complex in lead III helps foster the perception, probably due to wandering baseline.

Compounding the illusion is the ST-depression in lead aVL! This is one of the first things I look for when considering the ECG diagnosis of acute inferior STEMI.

It's helped me pick up on dozens of subtle presentations!

 
In the second graphic I've blown up lead II so you can clearly see the PR-segment depression.

This is important for two reasons. First, it fools your eye into the thinking that ST-segment elevation is present. Secondly, it fools the GE-Marquette 12SL interpretive algorithm!

Having said that, I have respect for the GE-Marquette 12SL interpretive algorithm, and I'm certain it also picked up on the ST-depression in lead aVL.

Keep in mind that the ACC/AHA STEMI criteria is far from perfect. I've called STEMIs before with less than 1 mm of ST-segment elevation, specifically when ST-depression was present in lead aVL.

This case demonstrate that sometimes, the emergency department is exactly where a suspected acute STEMI patient (with a marginal ECG) belongs until the diagnosis can be confirmed through other means.

I'll be posting the conclusion to the case in the next couple of days.

See also:

72 year old male CC: Unknown problem (man down) – Conclusion

Data quality, lead placement, your patient’s dignity, and undressing female patients

11 comments

I thought long and hard about allowing anonymous comments on the PH12ECG blog.

In my experience, anonymous posters don’t exercise the same level of responsibility as posters who use their real names or blogger identities.

Anonymous posters are often bomb throwers. Or, they engage in proselytizing, propagandizing, sensationalizing, or advertising.

For them, there are no consequences. That’s why it’s almost always a mistake to get into a discussion with an anonymous poster.

On the other hand, some anonymous posters might have something of value to add. Perhaps they simply have not bothered to register with a blogger account. Or, maybe they have their own reasons for posting anonymously, but they are intelligent, responsible people who want to express their opinions.

I received a comment from an anonymous poster yesterday who was replying to Muscle Tremors, Your Patient’s Dignity, and Staying Organized.

Anonymous wrote:

If you remove the bra of a female patient and you do not have her written consent be prepared for a law suit in most states. There is absolutely nothing to be gained in terms of quality unless you are a novice in removing the bra in doing an ekg. Remember this is not a decision that you make. The patients body belongs to the patient. NOT TO YOU.

Because this was in reference to a non-recent post, the comment ended up in my mailbox awaiting moderation.

This didn’t sound like a random comment left by one of my usual readers.

Here’s what I found under Recent Keyword Activity.


Whoever anonymous is, s/he typed the words “paramedics right to undress female patients” into Google and that’s apparently how s/he found my blog.

Let’s take this one step at a time.

If you remove the bra of a female patient and you do not have her written consent be prepared for a law suit in most states.

In the words of Daniel Patrick Moynihan, you are entitled to your opinion. You are not, however, entitled to your own facts.

Patients who possess the present mental capacity to understand their situation are presumed to have the ability to consent to medical procedures, and that consent need not be in writing.

Performing a 12 lead ECG is no different from placing a patient on oxygen, backboarding a patient, starting an IV, or taking a patient’s blood pressure. Paramedics aren’t required to obtain written consent for those procedures, and we aren’t required to obtain written consent to remove a patient’s clothes either.

If I explain to a patient that I need to perform a 12 lead ECG, and that I would prefer the patient be undressed from the waist up, and the patient says, “Do whatever you need to do.” and then leans forward so that I can unfasten her bra (or I hold up a sheet while she unfastens her bra) then the patient has legally consented to the procedure.

There is absolutely nothing to be gained in terms of quality unless you are a novice in removing the bra in doing an ekg.

I do not consider myself a novice when it comes to capturing and interpreting 12 lead ECGs, and I have found it to be beneficial to remove a female’s bra for several reasons, not the least of which is to help identify the correct landmarks for the placement of the V1 and V2 electrodes (which are frequently misplaced).

I have also found that attempting to place electrodes under clothing (including the bra) often leads to poor data quality.

As a practical matter, if the patient’s arms are through the bra, and you start an IV (as you should for any patient complaining of chest pain, shortness of breath, syncope, etc.) then you will eventually have to pass the IV bag through the shirt and bra if the patient is not undressed at the beginning of the patient encounter.

What would be the point of all that?

The patient will end up undressed and gowned at the hospital anyway.

For a female patient who is particularly modest or uncomfortable being undressed from the waist up in the back of an ambulance, I can see unfastening the bra and having the patient remove her arms, but keeping the cups of the bra over the breasts, if that would somehow help the patient psychologically.

Having said that, you would still need to lift the bra up to correctly place the V1 and V2 electrodes.

So what’s the difference between a bra and a sheet (or gown)?

In any case, you should only uncover the patient’s breasts as long as necessary to complete the procedure, and you should make every effort to protect the patient’s dignity.

I thought I had made that clear.

Remember this is not a decision that you make. The patients body belongs to the patient. NOT TO YOU.

I have no quarrel with the idea that the patient’s body belongs to the patient.

However, there is a third possibility you are overlooking.

Maybe it’s a decision you make with the patient’s consent.

The patient or the patient’s family, I presume, contacted 9-1-1 because some type of situation evolved beyond their span of control. Patients trust that paramedics will do what is in their best interest, with a high degree of expertise and professionalism.

In the 14 years I’ve been a paramedic, I have never had a female patient refuse to remove her bra for a 12 lead ECG once I explained the procedure, why it was indicated, and assured the patient that everything possible would be done to protect her dignity.

If, for whatever reason, my next female chest pain patient says, “I’d rather not take my bra off” then I’ll explain that the lead placement will have to be modified slightly to accommodate the request, but I will respect the patient’s right to refuse.

If I didn’t explicitly say that in my previous post, it’s because my readership consists mainly of medical professionals who already understand that.

Obtaining consent for procedures is part of every medical professional’s basic education.

If you had a bad experience with a particular paramedic or EMS system, I would suggest contacting the director of that system and filing a written complaint.

Data quality and computerized interpretive statements

10 comments

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.

Computerized interpretive statements – false positives #1

5 comments

Every time I’ve defended Southern California’s use of the GE-Marquette 12SL interpretive algorithm in their STEMI system I’ve taken some flack for it (see the comments section here and more recently in the EMS Responder forum here).

I agree that in a perfect world, paramedics would receive extensive 12 lead ECG training as part of their core education (including how to identify the STE-mimics and how to identify AMI in the presence of the STE-mimics).

Unfortunately, the vast majority of paramedics in the country are not receiving this level of training in school, and it’s not possible to read a 12 lead ECG at this level after an 8 hour crash course in 12 lead ECG interpretation.

That being the case, if you want to regionalize STEMI care, then there are only three options.

  1. Provide specialized training to paramedics (in my opinion it should be at least 24 hours) and allow them to bypass non-PCI hospitals based on their own interpretation.
  2. Provide less specialized training and use a computerized interpretive algorithm (i.e., when the computer says ***ACUTE MI SUSPECTED*** and the paramedic agrees the patient is taken to a PCI hospital).
  3. Provide less specialized training and transmit the ECG off-site for physician evaluation.

None of these solutions is perfect and some locations are using a combination of methods. I applaud Southern California for building a highly functional regional STEMI system. Is it perfect? No. Is there room for improvement? Of course.

It’s easy to criticize.

While it’s true that the GE-Marquette 12SL interpretive algorithm has a high specificity when it gives the ***ACUTE MI SUSPECTED*** message or ***ACUTE MI***, it’s not perfect. In fact, Southern California has a problem with false positives ECGs.

Note: the Philips MRx uses a different interpretive algorithm but the Physio-Control LP12 and ZOLL M and E series use the GE-Marquette 12SL interpretive algorithm, as do the majority of systems inside the hospital. To my knowledge, one is not been proven superior to the other.

Since some EMS systems are using the interpretive algorithms to influence whether or not patients are taken to PCI hospitals, I thought I would devote some time to discussing how to get the most out of them.

Interpretive algorithms are a tool like any other. They have limits and they require understanding. For example, you can get a false positive from the computer when you capture an ECG with poor data quality (which is one of the reasons I spend a lot of time talking about data quality).

Capturing a 12 lead ECG with good data quality is a sign of professionalism. Conversely, handing over (or transmitting) an ECG to the hospital with poor data quality shows a lack of professionalism.

There have been a couple of times in my career that no matter what I did, I couldn’t get a good tracing (Parkinson’s disease, bad electrodes, broken leads, combative patient) but it’s rare.

In addition to poor data quality, sometimes tachycardias can fool the interpretive algorithm, especially atrial flutter.

The specificity of the computerized interpretive algorithm is maximized when you capture the ECG with excellent data quality, the chief complaint is chest pain, and the heart rate is less than 100.

Even with these caveats, you will occasionally run into false positives.

Consider the following ECG.


You will notice that the data quality is pretty good (just a little bit of wandering baseline in lead V4).

The computer is giving the ***ACUTE MI SUSPECTED*** message.

Why?

48 year old male CC: chest discomfort, shortness of breath

5 comments

Here's an interesting 12 lead ECG that I found on the Lifenet Receiving Station at my receiving hospital. It immediately caught my eye for a couple of different reasons.

In the first place, it's an incomplete 12 lead ECG. Lead V1 is missing. This is probably the reason the GE/Marquette 12SL interpretive algorithm is giving the "Data quality prohobits interpretation" statement.

Let's move on.

There's a slight amount of wandering baseline in leads I, II, and III. However, if we ignore the first two cardiac cycles, it appears as though we have 1 mm of ST segment elevation in the inferior leads. In addition, there is a downsloping ST segment in lead aVL. That's a finding that always catches my eye!

Moving on to the precordial leads, the ST segment depression and T wave inversion in lead V2 and the flat, depressed ST segment in lead V3 are deeply concerning. This is a situation where the ability to view lead V1 would be extremely helpful, but I suspect it wouldn't look much different from lead V2.

When it comes to interpreting an abnormal finding on the 12 lead ECG, Tomas Garcia, MD is fond of saying "consider the company it keeps".

What does he mean by that?

Depending on circumstances, you might be able to dismiss an isolated abnormality or quirk on a 12 lead ECG. However, when those quirks start to multiply, and when they "fit" together (as these abnormalities do) your internal barometer should be rising with each observation.

This is a very subtle acute STEMI, but it's a STEMI none-the-less.

I did some investigating and found out that this patient ended up in the cardiac cath lab. I don't know how long it took, I don't know if the interpretive algorithm gave the ***ACUTE MI SUSPECTED*** statement when the ED performed their own 12 lead ECG, or if it was picked up by the emergency physician on duty.

However it happened, I'm glad the patient received reperfusion therapy! The reciprocal changes associated with posterior STEMI are sometimes misclassified as anterior ischemia. When the cardiac biomarkers come back positive, the patients are sometimes classified as NSTEMI.

How important is good data quality?

See also:

Anterior ischemia or posterior STEMI?

Pure (Isolated) Posterior STEMI – Not so rare, but often ignored!

Artifact in the limb leads: which electrode is responsible?

7 comments

This is the latest in a series of posts I am dedicating to achieving excellent data quality for prehospital 12 lead ECGs, particularly when they are being transmitted to the emergency department for physician interpretation (and early activation of the cardiac cath lab).

Lately I have noticed that when an ECG shows artifact in the limb leads, most paramedics start aimlessly checking the wires between the various electrodes and the ECG machine.

But why?

In my series on axis determination, we discussed Einthoven’s triangle, and how leads I, II and III are derived from the white, black and red electrodes.

Let’s look at the following ECG.

Since we’re in monitor mode, we’re not in the standard 12 lead ECG format. In other words, lead II is on top, lead III is in the middle, and lead I is on the bottom. By the way, this wasn’t my choice. This is just how my fire department chose to configure the default settings of the Lifepak 12 (either that or it’s how it came from the factory).

Where is the artifact on this tracing? Leads III and I. How about lead II? That looks fine. So which electrode is responsible for the poor data quality?

Let’s think about it. For lead II, the negative is the white electrode on the right shoulder. The positive is the red electrode on the left leg. Since lead II looks fine, we can deduce that the white and red electrodes are not responsible for this poor data quality. Which electrode do leads III and I have in common? The negative for lead III is the black electrode on the left shoulder. It also happens to be the positive electrode for lead I.

Ding, ding, ding! We have a winner! Or should I say, we have found our culprit. Check the black electrode. If necessary, peel it off, wipe the skin, and replace it with a new one.

Here’s another example.

I have a confession to make. I induced this abnormality on an emergency call the other day by partially peeling back one of the electrodes. But which one?

Lead III looks fine. The negative for lead III is the black electrode on the left shoulder. The positive for lead III is the red electrode on the left leg. We can speculate that the black and red leads are not responsible for this poor data quality. What’s left? The white electrode on the right shoulder. Do leads II and I share this electrode? You bet.

Make sense?

Here’s the coup de grâce.

This is from an actual emergency call.

The paramedics were called to the scene of an elderly male who wasn’t answering the phone at his apartment. The son went to check on him, and found him unresponsive and not breathing. When paramedics arrived at the scene, it appeared to be an obvious death (although there was no rigor mortis in the fingers and no dependent lividity was noted).

The cardiac monitor was attached and showed this tracing. The paramedics were surprised to see VF on the monitor. It seemed strange that lead II showed asystole, but CPR was initiated, the patient was defibrillated (many times), and the patient was ultimately transported lights and sirens to the emergency department.

Afterward, the paramedic in charge of the call faxed this ECG to me and asked my opinion as to why lead II showed flat line, when leads III and I showed VF.

My answer was simple. Did you check the black electrode?

What is the more likely scenario? That the VF was isoelectric in lead II (a theory a physician rendered at an ACLS class where this strip was shown) or something was wrong with the black electrode?

Let’s look at the history. This was an unwitnessed cardiac arrest! My money is on asystole and a bad black electrode!

Muscle Tremors, Your Patient’s Dignity, and Staying Organized

11 comments

The importance of good data quality to a successful prehospital 12 lead ECG program cannot be overemphasized. After all, life and death decisions are made based on the 12 lead ECG. If an EMS system routinely transmits garbage to the emergency department, it should come as no surprise to anyone that the cath lab isn’t being activated while the patient is still out in the field.

I’m not promising that an emergency physician will react appropriately to a “clean” 12 lead ECG that shows acute STEMI, but it certainly increases the probability of achieving a functional program.

Why give them an excuse?

This is an ECG of a 26 year old recruit firefighter. When it was taken, he’s was lying down on the kitchen counter at the fire station. One thing you should know about Station 6 is that it’s almost always cold. They don’t call it the “Ice House” for nothing (t-shirts available). You will notice muscle tremor artifact in every lead.

Now, who do you think feels colder? A healthy 26 year old recruit firefighter, or a 79 year old female who is accustomed to wearing three layers of clothing when it’s 80 degrees outside?


For this ECG we placed a large towel over the recruit firefighter to keep him warm. That’s quite an improvement, isn’t it? Keep your patient warm, have him relax and breath normally, and make sure he’s not propping himself up with his arms on the rail of the gurney (or any other type of furniture). Tension on skeletal muscles may be transmitted into the ECG.

I always follow the same steps when I capture a 12 lead ECG.

In the first place, I undress the patient from the waist up, including the bra (if it’s a female). When I do this, I communicate first. I will say something like, “Mrs. Smith, I need to perform a 12 lead ECG, so I need to undress you from the waist, up; including your bra. We’ll get you covered up just as soon as possible, and I’ll make every effort to preserve your dignity.”

This invariably elicits the response, “Do whatever you need to do.”

There’s no reason to perform a 12 lead ECG while the patient is still wearing clothes. Please don’t be one of those paramedics who reaches down the front of the patient’s shirt to place electrodes. I understand why you might be tempted to leave a female patient’s bra on, but don’t do it. Just be professional. If you need to lift up a patient’s breast, use the back of a gloved hand. When you’re finished, you can lay a towel, sheet, and/or blanket over the patient. Now when the nurses in the ED gown the patient, they don’t have to disconnect the IV (and break sterility) or pass the IV bag through the patient’s sleeve.

Any member of my crew will attest to the fact that I’m very particular about how I organize my patient. When I load the patient, I make sure that the patient is centered, sitting all the way back, and not slouching on the gurney. That way, if I place the patient in high Fowlers (as you might when you’re trying to undress the patient) the patient is actually sitting up.

I strand out each individual ECG lead so that they don’t wrap around each other, and I never allow the ECG leads, oxygen tubing, and IV line to become tangled. When I place the precordial leads on the patient’s chest, the (rectangular) electrodes are lined up with the edges parallel to each other. This is a matter of personal pride for me. When I look down and see a well organized gurney, with a squared away patient, it helps me feel in control of whatever situation I’m dealing with. I also believe that it helps me achieve excellent data quality with my 12 leads.

If you’ve ever been in an ambulance with a critical patient slumped to one side of the gurney, the ECG leads falling off, IV lines wrapped around oxygen tubing, the cardiac monitor beeping, and it looks like a bomb’s gone off in the back of the ambulance, it’s not a pretty sight. I’m not saying that I never trash the back of the ambulance, but it’s rare, and I don’t mind telling you that I’m not okay with it. Generally speaking, you can be as good at patient handling as you make up your mind to be.

Think of the back of your ambulance as your place of business, and your patient care as your product. If you’re okay with your patient looking like a train wreck, you probably don’t mind your 12 lead ECG looking like chicken scratch.

More troubleshooting tips to come!