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64 year old female CC: Trouble Breathing – Conclusion

13 comments

Lots of great comments and it was good to see the depth of discussion on the appropriate treatment and transport for this patient!

This is the conclusion to 64 year old female CC: Trouble Breathing.

When we left off our crew was attending to an elderly female patient in respiratory extremis. Pulmonary edema was present and their initial 12-Lead was concerning.

Many readers correctly noted the normal sinus rhythm, a 1° AV Block, and a wide QRS. Other readers pointed out the apparent Left Bundle Branch Block due to a negative QS complex in V1. Only a few readers picked up on the abnormal presentation of the LBBB: lead I has an rS complex and there is right axis deviation! Right axis deviation is a very uncommon finding in LBBB [1].

Just as it is important to know what a normal 12-Lead looks like, we also need to know what our abnormal 12-Leads should normally look like. In the case of LBBB, we expect V1 to be negative and leads I/V6 to have broad, monomorphic R-waves.

We also expect the T-waves to be discordant with the dominant deflection of the QRS. A picture is worth a thousand words in this case:

In our case we have three troubling findings:

  1. An rS complex in Lead I with Right Axis Deviation, which is very uncommon in LBBB.
  2. Concordant ST-segments in leads V5 and V6.
  3. Excessive ST-segement elevation in leads V2 through V4.

Many readers stated that a Left Bundle Branch Block is a STEMI mimic and precludes an activation of a STEMI alert until an old 12-Lead is used in comparison. However, criteria exists to diagnose a STEMI in the face of a LBBB or Paced rhythm.

Additionally, this patient's 12-Lead does not show a normal LBBB, but rather a non-specific intraventricular conduction defect or IVCD. Dr. Garcia would encourage, "considering the company it keeps," [2] which includes acute myocardial infarction!

Sgarbossa's criteria (and its modifications) for diagnosing STEMI in the face of LBBB or a Paced Rhythm has been covered in depth before so we'll only cover the positive criteria found on our 12-Lead:

  1. Is there ST-segment elevation ≥1 mm that is concordant with the QRS complex? Yes.

  2. Is there ST-segment depression ≥1 mm in leads V1, V2, or V3? No.
     
  3. Is there ST-segment elevation ≥5 mm, or ≥20% the depth of the S-wave, that is discordant with the QRS complex? Yes.

With 2 of the 3 criteria met (only 1 is required), we can be very confident that we're looking at a STEMI. Additionally, any concordant ST-elevation present should always suggest a STEMI.

The paramedic in this case recognized the concordant ST-elevation and the abnormal LBBB, called in a STEMI alert, and transported the patient to the PCI capable center. The patient improved significantly on the non-rebreather and CPAP was not necessary. Prior to arrival a second 12-Lead ECG was acquired:

Enroute the patient proved to be difficult for IV access, and received external jugular access in the ED. Labs were drawn while they waited for the cath lab team to arrive.

In the cath lab a 100% occlusion of the LAD was found and corrected with stenting.

For QA purposes an old ECG was retrieved after the call to compare to the field ECG:

Given this prior ECG, the new LBBB alone would likely cause a STEMI activation. However, in the absence of our more definitive changes this is a very weak criteria for activation [3].

Even without the prior ECG, we have an abnormal LBBB (most likely IVCD due to a peri-infarction block) with concordant ST-elevation and a patient presenting with signs of actue left sided heart failure: all of which point to an acute myocardial infarction!

This case highlights the importance of knowing what abnormal should normally look like and understanding that not every patient fits the protocol. We hope you enjoyed this case as much as we did, so be sure to continue the discussion below.

  1. Childers R, et al. Left bundle branch block and right axis deviation: a report of 36 cases. J Electrocardiol, 2000; 33 Suppl:93-102. [PubMed]
  2. The Art of Interpretation Series. http://www.12leadecg.com/
  3. Jain S, et al. Utility of left bundle branch block as a diagnostic criterion for acute myocardial infarction. Am J Cardiol, 2011; 107(8):1111-6. [PubMed]
Posted by on January 24, 2012 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , ,

88 year old female CC: Chest pain – Conclusion

4 comments

This is the conclusion to 88 year old male CC: Chest pain.

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

This ECG shows acute STEMI in the presence of left bundle branch block.

It's also an excellent example of the value of using "excessive discordance" to identify acute STEMI in the presence of left bundle branch block.

For a more extensive discussion of this topic see:

Excessive discordance as a marker of acute STEMI in LBBB

First, let's see if we can make the case for acute STEMI using Sgarbossa's original criteria.

As a refresher, here are Sgarbossa's criteria to identify AMI in the presence of LBBB

1.) ≥ 1 mm of concordant ST-elevation (in the same direction as the majority of the QRS complex) in at least one lead
2.) ≥ 1 mm of ST-depression in lead V1, V2 or V3
3.) ≥ 5 mm of discordant ST-elevation (opposite the majority of the QRS complex) in at least one lead

According to the original scoring algorithm, the more of these criteria that are met, the higher the probability of AMI.

 

So, let's apply these criteria to this case.

Do we see ST-elevation that is concordant with the majority of the QRS complex in at least one lead?

This criterion appears to be met in lead II.

Do we see ST-depression in leads V1, V2 or V3?

Possibly. I bring up data quality so often on this blog that I probably sound like a broken record, but it's rare that I run a case study where we don't have to compensate for poor data quality in one way or another. In this case it appears that ST-depression may be present in lead V1.

How about discordant ST-elevation = or > 5 mm?

This finding is absent on this 12-lead ECG. However, it doesn't really matter because this finding is (by far) the least specific of Sgarbossa's criteria. It's the least specific because it doesn't take into account the depth of the S-wave (rule of proportionality).

In other words, the deeper the S-wave, the greater the ST-elevation, and this is normal.

That's why we use the modified criterion proposed by Stephen Smith, M.D. (Dr. Smith's ECG Blog).

Rather than look for ST-elevation that is = or > 5 mm, we look for ST-elevation that is > than 0.2 (or 1/5) the depth of the S-wave!

To put this in a quick "rule of thumb" for you, for every 5 mm of S-wave depth, we allow 1 mm of ST-elevation.

Or, you can break out the calipers and calculate the ST/QRS ratio.

Let's apply the modified criterion to this case.

Do we see any leads with a ST/QRS ratio > 0.2?

We certainly do (and it's not even close).

So, lead II meets one of Sgarbossa's original criteria (concordant ST-elevation = or > 1 mm) while leads III and aVF meet Smith's modified criterion (ST/QRS ratio > 0.2).

This is more than enough evidence to call this an acute inferior STEMI in the presence of LBBB.

But we aren't finished yet!

Smith et al. discovered that "excessive discordance" works for positive and negative QRS complexes!

With this in mind, do we see "excessive discordance" anywhere else in this ECG?

Yes we do! Lead aVL shows ST-depression that is "excessively discordant" with the QRS complex.

Is lead aVL reciprocal to leads II, III and aVF?

Yes it is.

Point, game and match.

BTW, I also made the calculations for lead V4 because it looked close to me.

It was close, but no cigar. So take a good look at lead V4! This shows close to the maximum ST-elevation that is permitted for a QRS complex of this size.

Once you train your eye it's much easier to spot excessive discordance!

See also:

80 year old male CC: Chest pain

58 year old female CC: Chest pain

Posted by on May 1, 2011 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , ,

58 year old female CC: Chest pain – Conclusion

9 comments

Here’s the conclusion to the 58 year old female with chest pain and left bundle branch block.

To refresh your memory here is the 12-lead ECG.

And for those of you who requested lead V4R.

This ECG meets all 3 of Sgarbossa’s criteria to identify acute STEMI in the presence of left bundle branch block.

Keep in mind, it only has to meet one criterion in one lead!

(Please note: One criterion has been modified from its original form. Instead of discordant ST-elevation > 5 mm we are looking for discordant ST-elevation > 0.2 the depth of the S-wave. This is known as the ST/QRS ratio. Credit to Dr. Smith of Dr. Smith’s ECG Blog.)

Angiography revealed 100% occlusion of the LCX and 99% occlusion of the RCA.

Thanks to everyone who commented on the case!

See also:

80 year old male CC: Chest pain

Excessive discordance as a marker of acute STEMI in LBBB

80 year old male CC: Chest pain – Conclusion

62 year old male CC: Chest pain (LBBB with ST-elevation > 0.2 the QRS complex)

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part I

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part II

“New” LBBB – What’s the big deal?

Discordant ST-segment elevation in LBBB or paced rhythm

Sgarbossa’s Criteria – New Graphic

Found on the Lifenet Receiving Station (LBBB with concordant ST-depression in leads V3 and V4)

Posted by on July 25, 2010 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , , , , , , , ,

58 year old female CC: Chest pain

22 comments

Here’s another case study from an international reader who wishes to remain anonymous.

Presenting Complaint – Chest Pain

History of Present Complaint – 58 year old female, nil cardiac history, mild smoker, social drinker and overweight.

Complaining of acute central chest pain @ rest. Awoken by pain.

On Arrival – Sat upright on settee (Editor’s note: One of you Brits will have to interpret that for me!)

On examination:

Alert, orientated and communicable (GCS 15)
Pale, cool dry skin.

Nil SOB, clear bi-lateral air entry – nil adventitious breath sounds
R/R 19, SpO2 99%

H/R 68 and irregular, BP 125/74

Temp 36.8
B.M 7.2 (Editor’s note: B.M. is BGL measured in millimoles. 1 mmol/L of glucose is equivalent to 18 mg/dL. Hence, this patient’s sugar is about 130).

C/O chest pain.

O – Acute. Awoken from sleep.
P – Nothing makes pain better. Not affected by breathing
Q – Non specific compressing type pain
R – Central chest pain radiating left arm
S – Pain score 6/10
T – 30 mins
I – No pain intervention sought.

Slight nausea, nil vomit

The cardiac monitor is attached.

A 12-lead ECG is captured.

How would you treat this patient?

See also:

80 year old male CC: Chest pain

Excessive discordance as a marker of acute STEMI in LBBB

80 year old male CC: Chest pain – Conclusion

62 year old male CC: Chest pain (LBBB with ST-elevation > 0.2 the QRS complex)

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part I

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part II

“New” LBBB – What’s the big deal?

Discordant ST-segment elevation in LBBB or paced rhythm

Sgarbossa’s Criteria – New Graphic

Found on the Lifenet Receiving Station (LBBB with concordant ST-depression in leads V3 and V4)

Posted by on July 23, 2010 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , , , , , ,

Sgarbossa’s Criteria – New Graphic

7 comments

Here is a graphic I created to help explain Sgarbossa’s criteria for identifying acute myocardial infarction (AMI) in the presence of left bundle branch block (LBBB) or paced rhythm.

In a previous article I showed this graphic which was created using PowerPoint.

Here is a similar graphic I created this morning by cropping actual ECGs that meet the criteria.


These are the features we should be looking for with LBBB and ventricular paced rhythms!

See also:

80 year old male CC: Chest pain

Excessive discordance as a marker of acute STEMI in LBBB

80 year old male CC: Chest pain – Conclusion

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part I

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part II

“New” LBBB – What’s the big deal?

Discordant ST-segment elevation in LBBB or paced rhythm

Found on the Lifenet Receiving Station (LBBB with concordant ST-depression in leads V3 and V4)

62 year old male CC: Chest pain (LBBB with ST-elevation > 0.2 the QRS complex)

58 year old female CC: Chest pain

58 year old female CC: Chest pain – Conclusion (meets all 3 of Sgarbossa’s criteria)

Posted by on January 3, 2010 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , , , , , , ,

Identifying STEMI in the presence of LBBB – Sgarbossa’s Criteria – Part II

9 comments

In Part I, we discussed Sgarbossa’s Criteria for identifying AMI in the presence of LBBB. We also talked about the “rule of appropriate T wave discordance” for bundle branch blocks and other forms of abnormal depolarization (like ventricular rhythms or paced rhythms).

You will recall that I drew a distinction between a QRS complex’s main deflection and its terminal deflection, even though they are one in the same for LBBB. I explained that it’s helpful to think in terms of the terminal deflection, because then you can apply the “rule of appropriate T wave discordance” to RBBB as well as LBBB.

And so you can!

Let’s look at an ECG.

This is from one of my “old” 12 lead ECG classes. In those days, I cropped the computer measurements and interpretive statements because I didn’t want the students to “cheat”. Nowadays, whether it’s EMS or firefighting, I’ve come to believe in reality-based training. In real life, for good or bad, you get an interpretive statement.

But, this ECG is a good example of an important concept.

So let’s look at this ECG. It’s a sinus rhythm. It has a normal axis. We know that for several reasons.

The QRS complex is smallest in lead aVL, so the perpendicular lead on the hexaxial reference system is lead II. Lead I is almost equiphasic so the perpendicular lead is aVF. The value of lead II is 60 degrees and the value of lead aVF is 90 degrees, so the frontal plane axis is somewhere between 60 and 90 degrees.

Or, to do it the “easy” way, lead I and lead aVF are both positively deflected, so we know we’re in the left inferior quadrant.

Or, because leads I, II, and III are all positive, so we know the axis is normal.

It really doesn’t matter what method you use. I use all three for every ECG.

The QRS duration is wide. When supraventricular rhythms are wide, we look at lead V1 to see if it shows RBBB or LBBB morphology. This ECG shows a terminal R wave in lead V1, which is RBBB morphology. Next we check lead I and look for a terminal S wave. We find one!

This is a simple RBBB.

You will notice that in many leads, the T wave is deflected the same direction as the QRS complex (II, III, aVR, aVF, V2, V3, V4, V5, and V6). In other leads, the T wave is deflected opposite the main deflection of the QRS complex (aVL, V1). I did not list lead I because the QRS complex is close to equiphasic.

So, how should these T waves be deflected?

The answer is, they should be deflected opposite the terminal deflection of the QRS complex, and so they are!

Look at the following image.

As you can see, when the terminal deflection of the QRS complex is negative, the T wave is positive. When the terminal deflection is positive, the T wave is negative. In other words, even if the main deflection of the QRS complex is positive, as long as the terminal deflection (or last deflection) is negative, the T wave is positive.

That’s why I’m encouraging you to always think in terms of the terminal deflection, even though for LBBB, the terminal deflection is also the main deflection.

There is method to this madness!

Although not part of Sgarbossa’s Criteria, the “rule of appropriate T wave discordance” can help you pick up on AMI in the setting of RBBB (or bifascicular block) because an inappropriately concordant ST segment and/or T wave can tip you off that something is wrong!

For example, this case from Dr. Smith’s ECG blog.

In the last lesson, we introduced Sgarbossa’s Criteria. Let’s take a look at a graphic that shows exactly what we’re looking for.

The first example shows > 1 mm of concordant ST segment elevation (and a concordant T wave). Both are abnormal for LBBB.

The second example shows > 5 mm of discordant ST segment elevation and a discordant T wave. Discordant ST segment elevation > 5 mm is abnormal for LBBB (with one very important caveat) but a discordant T wave is normal for LBBB!

In the last example, there is concordant ST segment depression in the right precordial leads, which is abnormal for LBBB, but a discordant T wave, which is normal for LBBB.

If you have a patient with signs and symptoms consistent with ACS and the ECG shows LBBB with concordant ST segment elevation, then chances are excellent that you are dealing with a STEMI.

Likewise, if you have a patient with signs and symptoms consistent with ACS and the ECG shows LBBB with concordant ST segment depression, especially in the right precordial leads, then chances are excellent that you are dealing with a STEMI.

The original criteria didn’t take into account the depth of the S wave, and as we know from other STE-mimics like LVH, the deeper the S wave, the higher the ST segment elevation. So a blanket statement that 5 mm of discordant ST segment elevation indicates acute STEMI in the setting of LBBB is not helpful in those situations where the S wave is > 50 mm deep like the example below.

Stephen Smith, M.D. of Dr. Smith’s ECG Blog has suggested that a more sensitive and specific marker is discordant ST-elevation > 0.2 the depth of the S wave (ST/QRS ratio).

See also:

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part I

80 year old male CC: Chest pain

Excessive discordance as a marker of acute STEMI in LBBB

80 year old male CC: Chest pain – Conclusion

“New” LBBB – What’s the big deal?

Sgarbossa’s Criteria – New Graphic

Discordant ST-segment elevation in LBBB or paced rhythm

Found on the Lifenet Receiving Station (LBBB with concordant ST-depression in leads V3 and V4)

62 year old male CC: Chest pain (LBBB with ST-elevation > 0.2 the QRS complex)

58 year old female CC: Chest pain

58 year old female CC: Chest pain – Conclusion (meets all 3 of Sgarbossa’s criteria)

Posted by on December 15, 2008 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , , , , , , , , ,

Identifying STEMI in the presence of LBBB – Sgarbossa’s Criteria – Part I

18 comments

There has been a lot of discussion lately about identifying AMI in the presence of LBBB (see Dr. Bearemy’s “My Emergency Medicine Blog” here and a recent thread on the EKG Club). I’ve also been receiving a lot of emails offlist, so I think a full discussion is in order.

In my recent post Who benefits the most from reperfusion therapy? I posted a graph that demonstrates how patients with new bundle branch block benefit the most from reperfusion therapy.

*** Important Update ***

Recent evidence suggests that new (meaning previously undetected) LBBB patients do not “rule-in” for AMI at any greater rate than any other group of patients! That’s why it’s so important for health care practitioners to understand Sgarbossa’s criteria! Those are the patients who need immediate reperfusion therapy in the cardiac cath lab!

*** End Update ***

The problem is that in many prehospital 12 lead programs (and regional STEMI systems), patients with LBBB or a QRS duration > 0.12 sec (120 ms) are excluded! In other words, patients with wide QRS are taken to the local community hospital without interventional capability. Or, the cath lab is not activated while EMS is still in the field.

Why would you exclude the very patients who stand to benefit the most from prompt, expertly performed PCI at a cardiac center?

Simple.

It’s too difficult to figure out whether or not the BBB is new! The ECG diagnosis of STEMI can be difficult in the setting of BBB.

In False Positive Cardiac Cath Lab Activations I reviewed Larson, Menssen, Sharkey et all, False-Positive” Cardiac Catheterization Laboratory Activation Among Patients With Suspected ST-Segment Elevation Myocardial Infarction, JAMA 2007;298(23):2754-2760.

I quoted:

Patients with new or presumably new left bundle-branch block had an inordinately high prevalence of false positive catheterization laboratory activation (almost half did not have a culprit artery). Patients with a previous myocardial infarction or previous coronary bypass surgery had a significantly higher prevalence of no culprit artery, likely because of abnormal baseline ECG results.

This is obviously a big problem, and subjecting all patients with LBBB and signs and symptoms of ACS to an emergent cath or the risks associated with thrombolytic therapy is not the answer, as some authors have suggested.

If only there was some kind of algorithm that could help distinguish between patients with LBBB and acute STEMI from patients with LBBB who are not experiencing acute STEMI.

But there is such an algorithm! It’s been around for over 10 years!

The GUSTO investigators Sgarbossa et al., Electrocardiographic Diagnosis of Evolving Acute Myocardial Infarction in the Presence of Left Bundle-Branch Block. N Eng J Med 1996; 334(8):481-487 published an algorithm which has come to be known as “Sgarbossa’s Criteria”.

The criteria seems complicated but it’s really not. Like anything else, it’s a tool. A very important tool for a critical subset of patients.

The original paper contains a flow chart from which the patient receives a score. I’m not going to publish the flow chart, because it’s not something you need to memorize.

Here is the criteria. A patient is presumed to be experiencing an evolving AMI if any of the following are present.

  1. ST segment elevation = or > 1 mm that is concordant with the QRS complex.
  2. ST segment depression = or > 1 mm in leads V1, V2, or V3.
  3. ST segment elevation = or > 5 mm that is discordant with the QRS complex.

It is the last criterion that has caused the most controversy and requires qualification.

However, before we address the third criterion, we have to dispose of a common misunderstanding.

What do we mean by concordant and discordant? The short answer is, concordant means “the same direction” and discordant means “the opposite direction”.

The rule of appropriate T wave discordance

In the presence of abnormal ventricular depolarization (left bundle branch block, right bundle branch block, paced rhythm, ventricular rhythms) the T wave should be deflected opposite the terminal deflection of the QRS complex (appropriate T wave discordance).

What is the terminal deflection?

The terminal deflection is the last deflection, or wave, of a QRS complex.

Please take the time to learn this! It is extremely important!

Take a look at the following image.

You will notice that each of these QRS complexes is labeled according to the waves are present. If the wave is large, it gets a capital letter. If the wave is comparatively small, it gets a lowercase letter.

I could talk about this image for a long time, but for now, I just want you to notice that an Rs complex is positively deflected while an rS complex is negatively deflected, even though both of them contain only an R and an S wave. But the terminal deflection of each is negative, because they both end in an S wave!

Why is this important?

When teaching Sgarbossa’s Criteria, students always get confused as to whether or not the ST segments and T waves should be deflected opposite the main deflection of the QRS complex or opposite the terminal deflection.

Well, guess what?

With LBBB, the terminal deflection is the main deflection!

So why are we splitting hairs?

Because if you learn to think in terms of the terminal deflection, you can use the rule of appropriate T wave discordance for RBBB, too!

Let’s start by looking at a patient with a normal LBBB.

I have no idea why the GE-Marquette 12SL interpretive algorithm is giving the “data quality prohibits interpretation” message for this ECG. There’s a little bit of artifact in the inferior leads, but it’s not that bad!

This is a normal looking LBBB. We know the frontal plane axis is around 0 degrees, because the QRS complex is isoelectric in lead aVF. Therefore, the perpendicular lead in the hexaxial reference system is lead I. Since lead I is positively deflected, we can place the frontal plane axis at 0 degrees. A physiological left axis deviation (0 to -30) is normal for left bundle branch block.

To put it another way, a negative QRS complex in lead III is normal for LBBB, but it should be upright and monomorphic in lead I.

Now, let’s look at the QRS complexes and the T waves.

You will notice that in every lead, the T wave is deflected opposite the QRS complex! This is “appropriate T wave discordance” in the presence of left bundle branch block.

To help illustrate this point, consider the following graphic.

The blue arrow shows the direction of the terminal deflection of the QRS complex (which is also the main deflection in the setting of LBBB). The red arrows shows the direction of the ST segment and the T wave.

This is what we mean by “appropriate T wave (and ST segment) discordance” with LBBB. Note that with RBBB, the T wave should be discordant, but the ST segment should remain isoelectric. This is why RBBB is usually not listed as a STE-mimic.

With LBBB, there is also a discordant shift of the ST segment, which is why it’s one of the most common STE-mimics! ST segment elevation in the right precordial leads (V1-V3) is a normal finding for LBBB!

In Part II, we’ll look at the “rule of appropriate T wave discordance” as it applies to RBBB and talk more about Sgarbossa’s Criteria.

See also:

Identifying AMI in the presence of LBBB – Sgarbossa’s Criteria Part II

80 year old male CC: Chest pain

Excessive discordance as a marker of acute STEMI in LBBB

80 year old male CC: Chest pain – Conclusion

“New” LBBB – What’s the big deal?

Sgarbossa’s Criteria – New Graphic

Discordant ST-segment elevation in LBBB or paced rhythm

Found on the Lifenet Receiving Station (LBBB with concordant ST-depression in leads V3 and V4)

62 year old male CC: Chest pain (LBBB with ST-elevation > 0.2 the QRS complex)

58 year old female CC: Chest pain

58 year old female CC: Chest pain – Conclusion (meets all 3 of Sgarbossa’s criteria)

Posted by on December 13, 2008 • Filed under: ems-topics, patient-management • Tagged: , , , , , , , , , , , , , , , , , , , , , , , ,