The ECG in Figure-1 was obtained from a previously healthy middle-aged woman who was involved in a severe MVA (Motor Vehicle Accident). She was being resuscitated per trauma protocol — and she was hemodynamically stable at the time this tracing was recorded.
QUESTION:
- Given the above clinical setting — How would you interpret the ECG in Figure-1?
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| Figure-1: The initial ECG in today's case. The patient was in a severe MVA. (To improve visualization — I've digitized the original ECG using PMcardio). |
My Thoughts on Figure-1:
Given the history of involvement in a severe MVA — I immediately considered a cardiac contusion as contributing to the abnormal ECG in Figure-1.
- The rhythm is a regular WCT (Wide-Complex Tachycardia) at a rate of ~130/minute. I suspected that the regular upright deflections preceding each QRS complex in lead II were sinus P waves (broken line RED arrows in this lead in Figure-2).
- Seeing similar upright deflections preceding each QRS complex in neighboring lead I at the same moment in time — is in support of the likelihood that the rhythm is sinus tachycardia.
- That said, given the rapid rate and the presence of small deflections that appear to notch the ST segments midway between the RED arrows in lead II (broken line BLUE arrows in Figure-2) — I could not rule out the possibility of 2:1 atrial activity, as might occur with atrial flutter. I also did not clearly see sinus P waves in either lead V1 or V2, as I would expect with sinus tachycardia.
As noted — the QRS looks wide.
- To Emphasize: QRS morphology is consistent with RBBB (Right Bundle Branch Block) — given the qR pattern in lead V1 — with wide terminal S waves in lateral leads I and V6.
- Therefore, at the least — this regular WCT rhythm is almost certain to be supraventricular. I could not completely rule out the possibility of 2:1 conduction — but strongly suspected the rhythm was indeed sinus tachycardia (ie, The history of a traumatic MVA is certainly consistent with sinus tachycardia — without having to postulate another form of tachyarrhythmia).
- PEARL #1: When we suspect a given etiology for the rhythm (as I suspected sinus tachycardia for the rhythm in Figure-2) but we are not 100% certain of that diagnosis — it is best to reserve final judgement until we are able to approach 100% certainty.
- Practically speaking — our initial management of today’s patient will not be different regardless of whether we are dealing with sinus tachycardia, ATach or AFlutter (ie, In all 3 situations — We would continue protocols for trauma assessment and treatment until such time that we better appreciate the extent of this patient’s injuries). And, if the rhythm is sinus tachycardia — the heart rate will almost certainly decrease with fluid resuscitation and other treatment measures.
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| Figure-2: I’ve labeled potential signs of atrial activity in leads I and II. |
What Else do We See on Today’s Initial ECG?
There are many additional findings to be concerned about on today’s initial ECG — which I’ve highlighted in Figure-3:
- There is extremely low voltage in 10/12 leads (ie, in all leads except V1,V2 — in which the reason the R wave may be as tall as it is in leads V1,V2 — may simply be a reflection of delayed and independent depolarization of the right ventricle, as physiologically occurs when there is RBBB).
- PEARL #2: As suggested in ECG Blog #272 — among the causes of Low Voltage is low cardiac output, as may occur as a result of a large MI (or in today’s case, as a result of a significant cardiac contusion).
- There are also diffuse QRST abnormalities that are seen in virtually every lead in this tracing.
Regarding Q-R-S-T Wave Changes:
- Q Waves — are present in multiple leads ( = the 5 YELLOW arrows in Figure-3). These include leads V1,V2 (ie, loss of the initial positive r wave deflection that should normally be seen in these leads with RBBB) — in neighboring leads V3,V4 (In addition to tiny voltage in these leads — there is absence of any initial positive r wave deflection) — and in lead aVL (which manifests a relatively large Q wave given tiny size of the QRS).
- R Wave Progression — is altered by the tall R waves in V1,V2 from the RBBB — but thereafter is marked by loss of R wave amplitude, with transition never occurring (ie, R wave amplitude remains smaller than the S wave is deep across the precordium, extending to lead V6).
- There is marked ST elevation in leads I and aVL (within the RED rectangles in these leads in Figure-3). Equally marked reciprocal ST depression is seen in each of the inferior leads (BLUE arrows in these leads).
- Marked ST elevation is also seen in lead aVR.
- To Emphasize: Considering tiny size of QRS amplitude in the limb leads — the relative amount of ST segment deviation (elevation and depression) is enormous.
ST-T wave changes in the chest leads are more subtle:
- Normally with RBBB — the ST-T wave will be oppositely directed to the positive terminal R wave. Instead, there is subtle-but-significant ST elevation in lead V1 – with more marked ST elevation in lead V2 (within the RED rectangle in these leads).
- The unsteady baseline makes assessment more difficult for ST-T wave changes in leads V3,V4,V5. But especially considering tiny size of the QRS in lead V6 — there is significant ST depression in this lead (BLUE arrows in lead V6).
Impression of ECG #1: If the history associated with this tracing was that of new chest pain — our impression would be that an extensive STEMI was ongoing, with tachycardia, developing Q waves in many leads, RBBB and marked low voltage — all of which suggest cardiogenic shock.
- Given the history of a severe MVA — these ECG findings could all be explained by MVA-related trauma causing Cardiac Contusion.
- And/or — the trauma and stress of the accident may have also precipitated either an acute MI and/or Stress Cardiomyopathy (which would be consistent with what appears to be QTc prolongation).
- ST elevation in lead aVR, in association with marked inferior lead ST depression and ST depression in lead V6 — may reflect DSI (Diffuse Subendocardial Ischemia). DSI is not an unexpected finding given the rapid heart rate and diffuse myocardial injury pattern seen in today's initial ECG (See ECG Blog #483 — for more on DSI).
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| Figure-3: In addition to diffuse low voltage — I've highlighted multiple Q-R-S-T abnormalities in the initial ECG. |
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What are the ECG Findings of Cardiac Contusion?
Overall — the ECG is less than optimally sensitive for detecting cardiac injury following blunt trauma. This is because the anterior anatomic position of the RV (Right Ventricle), and its immediate proximity to the sternum — makes the RV much more sussceptible to blunt trauma injury than the LV. But because of the much greater electrical mass of the LV — electrical activity (and therefore ECG abnormalities) from the much smaller and thinner RV may sometimes be more difficult to detect.
PEARL #3: Regarding ECG findings with Cardiac Contusion (using the following sources — Sybrandy et al: Heart 89:485-489, 2003 — Alborzi et al: J The Univ Heart Ctr 11:49-54, 2016 — and Valle-Alonso et al: Rev Med Hosp Gen Méx 81:41-46, 2018) — I found the following ECG findings to be most commonly reported.
- None (ie, The ECG may be normal — such that not seeing any ECG abnormalities does not rule out the possibility of cardiac contusion).
- Sinus Tachycardia (common in any trauma patient … ).
- Other Arrhythmias (PACs, PVCs, AFib, Bradycardia and AV conduction disorders — potentially lethal VT/VFib).
- RBBB (as by far the most common conduction defect — owing to the more vulnerable anatomic location of the RV). Fascicular blocks and LBBB are less commonly seen.
- Signs of Myocardial Injury (ie, Q waves, ST elevation and/or depression — with these findings suggesting LV involvement).
- QTc prolongation (with the QTc looking "long" in Figure-3 — albeit much harder to accurately determine the QTc in today's initial ECG given the tachycardia).
Additional Important Points:
- Prediction of cardiac contusion “severity” on the basis of cardiac arrhythmias and other ECG findings — is an imperfect science.
- Despite the predominance for RV (rather than LV) injury — use of a right-sided V4R lead has not been shown to be helpful (compared to use of a standard 12-lead ECG for detecting ECG abnormalities).
- In addition to ECG abnormalities related to the blunt trauma of cardiac contusion itself — Keep in mind the possibility of other forms of cardiac injury in these patients (ie, valvular injury, aortic dissection, septal rupture) — as well as the possibility of a primary cardiac event (ie, acute MI may have been the cause of an accident that led up to the trauma).
- ECG abnormalities may be delayed — so repeating the ECG if the 1st tracing is normal is appropriate when concerned about severe traumatic injury.
- The "good news" re assessing risk when cardiac contusion is suspected in association with acute trauma — IF troponin is normal at 4-6 hours and IF the ECG is normal — then the risk of cardiac complications is extremely low.
Given the multiple ECG abnormalities described above in today's initial ECG — significant cardiac involvement is obvious. Whether this is the purely the result of cardiac contusion and/or whether an acute MI is also implicated — would not be known solely from review of the initial ECG.
PEARL #4: An Often-Ignored ECG Finding ...
We do not usually think of the ECG as a way of estimating a patient's respiratory rate. That said — awareness that on occasion we can estimate how fast the patient is breathing may at times be extremely helpful.
- This is especially true when charged with interpreting the ECG of a patient we have not seen. For example — the ECG suggestion of tachypnea may clue us in to a patient with respiratory difficulty who needs to be immediately seen.
Consider Figure-4 — in which I've magnified the view of leads V1,V2,V3 from the initial ECG in today's case.
- Note the rhythmic rise-and-fall in the baseline seen every 3 QRS complex.
- When you see a consistent rise and fall of the baseline occurring at a fixed interval over a majority of the 12-lead recording — this most probably reflects the patient's respiratory rate (to be distinguished from the much more common random baseline variation — from which the patient's respiratory rate can not be accurately assessed).
- In Figure-4 — 2 breaths are seen to occur over a period of 2.8 seconds (ie, over a period of 14 large boxes). This means that 1 breath occurs over a period of 1.4 seconds — and 60 sec./min. ÷ 1.4 seconds = tachypnea at a respiratory rate of ~43/minute (which is not surprising given that the initial ECG suggests this patient is in shock).
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| Figure-4: Use of the ECG to estimate respiratory rate. |
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Today's CASE Continues:
The patient was resuscitated by trauma protocol:
- Musculoskeletal injuries were treated.
- The patient received blood products.
- She was intubated to secure the airway — followed by additional fluid resuscitation and sedation.
- Serum electrolytes were normal.
- Bedside Echo suggested anterolateral akinesis (consistent with the very low voltage and anatomic distribution of Q waves and ST elevation).
Minutes later — the patient developed the rhythm shown in Figure-5.
- QUESTION: What has happened?
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| Figure-5: The patient suddenly developed the rhythm shown in the chest leads. |
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MY Thoughts on the ECG in Figure-5:
A total of 26 beats are seen in ECG #2 — with the first 9 beats appearing in the limb leads.
- The limb leads show little change since ECG #1 — with sinus tachycardia again suggested as the underlying rhythm (at the same very rapid rate of ~130/minute). We once again see very low voltage — with a similar amount of ST elevation in leads I,aVL and reciprocal ST depression in the inferior leads.
- Beat #10 is partially hidden by the lead change border.
- Beat #11 is the first complete beat seen in the chest leads. It shows the same RBBB morphology (with initial Q wave and similar ST elevation in leads V1,V2). Looking down at simultaneously-occurring beat #11 in the long lead II rhythm strip (at the bottom of the tracing) — we can see that beat #11 is sinus-conducted (the RED arrow preceding beat #11 in the long lead II rhythm strip).
- Note that P waves are lost in the long lead II after beat #11.
- Turning our attention to lead V1 — a 13-beat run of a very different-looking WCT rhythm begins with beat #12. The rate of this almost regular WCT rhythm is over 200/minute. The very wide and amorphous QRS morphology in leads V1 and V2, along with marked change in QRS morphology during this 13-beat run in leads V3,V4,V5 is virtually diagnostic of VT (Ventricular Tachycardia).
- QRS morphology almost normalizes for the last 2 beats in this tracing ( = beats #25,26) — suggesting that the run of VT may be terminating (although we are not privy to what happens after beat #26).
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| Figure-6: I've numbered the beats and have labeled P waves. |
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CASE Follow-Up:
The patient had several episodes of NSVT (Non-Sustained VT ).
- Over the ensuing days — the patient's condition stabilized. VT episodes ceased. She remained on ventilator support. Echo documented an EF ~25-30%.
- Unfortunately — I do not have longterm follow-up of this case. The NSVT episodes and low ejection fraction are not unexpected given the diagnosis of a severe cardiac contusion in association with the diffuse ECG abnormalities seen in Figure-3.
- That said — the fact that this patient's condition seemingly stabilized and was continually improving after several days in intensive care bodes well for her potential recovery.
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Acknowledgment: My appreciation to Mehul K (from Delhi, India) for submission of today's case.
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