April 2015: Sighting the Subtlety Down Below

CASE: 

A 63 y/o gentleman calls 911 for "chest pressure" and indigestion. The patient is nauseated but denies LOC, SOB, or dizzinesss. The pressure started approximately 1 hour prior to 911 arrival. The patient has a history of hypertension and takes an aspirin daily. He is hemodynamically stable. BP is 110/70, P: 82, R: 16. Sp02: 95% on RA.

12 LEAD ECG:

12 LEAD ECG DISCUSSION:

There is a sinus rhythm. PR depression is present in lead II. There is slight ST segment elevation present in II, III, and aVF. Elevation measures about 1 mm. There is no evidence of recriprocal change. A biphasic T wave is present in lead III and terminal T wave inversion is present in the lateral precordial leads. The QRS axis appears physiologic.

12 LEAD INTERPRETATION: 

Inferior wall STEMI

TREATMENT

The patient was transported to a hospital capable of percutasneous coronary intervention. A right sided ECG was not performed, and NTG was withheld due to the patient's marginal blood pressure or relative hypotension. 325 mg of ASA was administered. The patient's RCA was 75% occluded.

Thanks always to the Baltimore City Fire Department for its endless supply of pathologic 12 lead tracings.

Well, I didn't see anything in the rhythm strip...

Case Description


Medics respond to the report of a 66 yo male with nausea, chest pain, and chest pressure radiating to the left arm. The patient appears well. Chest discomfort started 2 hours prior to EMS arrival. The patient's vital signs are as follows: BP: 168/100, P: 72, R: 60/regular. Sp02: 96% on RA. Physical examination is unremarkable. The patient is loaded for transport, and the paramedics consider aspirin and nitrates. A 12 lead ECG is obtained


12 lead ECG

12 Lead ECG Interpretation and Discussion 

The rhytm is sinus in origin, and there does not appear to be any ectopic beats. ST segments are upright with the exception of expected T wave inversion in lead aVR. Careful scrutiny of the inferior leads reveals subtle ST segment elevation of approximately 1 mm. ST segments should be measured at the "J" point, and there is just about 1 mm / 1 box of elevation in the inferior leads. Further substantiating the findings of ischemia are the ST segment elevations present in leads V2-V5. The ST segments takes on an almost horizontal appearance in V5 and the R wave progression is preserved. Reciprocal change in the form of ST segment flattening and depression appears in leads I and aVL. When deciding if any one ECG represents ischemic patterns look for (1 ) anatomic distribution of abnormal findings and (2) reciprocal changes. This ECG features both of these findings. This patient was transported for urgent PCI; I do not have angiographic findings available. The ST elevation in the limb leads is not all that impressive. It is easy to imagine that placing this particular patient "on the monitor" would interfere with the recognition of concerning ST-T changes in the precordial leads. 

Closer look at ST segment ugliness

12 Lead Interpretation

Sinus rhythm, rate of 60, widespread ST segment elevation in the inferior and anterior-lateral leads concerning for acute ischemia.

Pearls

• If there is ANY suspicion for coronary ischemia or cardiac-related chest pain, perform a complete 12 lead
• The presence of recipocal change makes the diagnosis of ischemia more likely
• Territorial ST-T changes (anterior, lateral, inferior) are similarly concerning for ischemia

Thoughts on another acute process that might produce widespread, diffuse STE? 

There's STE in V1 !

EMS responds to the report of a 77 year old male with chest pain. The patient is hypertensive, alert, and hemodynamically stable. Aspirin and nitroglycerin are administered per treatment protocol. A 12 lead ECG is obtained, and the paramedic asks about transport to the closest hospital versus a facility capable of percutaneous coronary intervention...


12 lead ECG



12 lead ECG Discussion

There is a baseline sinus rhythm. The rhythm is regular. Close scrutiny of lead II and V1 reveals the presence of p waves. The ST segments are upright in most leads with the exception of aVR. The QRS duration is slightly prolonged consistent with an interventricular conduction delay. The (1) positively deflected QRS in lead V1 and the (2) lengthened QRS duration suggests the presence of a RIGHT bundle branch block. There is a subtle slurred l S wave in V6 which further corroborates the diagnosis of a right bundle branch block.

The Slurred S Wave

12 lead ECG Interpretation

Sinus rhythm, right bundle branch block, rate of approx 80 beats/min.

Case resolution

The patient was transported to a local facility. Serial ECGs remained unchanged and cardiac enzymes were normal. The patient was discharged to home following an overnight hospital stay and a cardiac stress test.

The History of Present (and Past) Illness

EMS responds to the home of a 69 yo male patient. The patient reports retrosternal chest pain x 3 hours. The patient has taken 2 of his own nitroglycerin without relief. The patient reports mild shortness of breath. He denies nausea or loss of consciousness. The  patient is slightly diaphoretic and states, "you know, this feels entirely similar to my previous MI's." The patient has a history of coronary artery disease, HTN, and placement of three metal stents.

Vital signs:
BP: 180/100
P: 90
R: 22

Sp02: 94%

12 Lead ECG:

12 Lead ECG Interpretation and Discussion:

There is a baseline sinus rhythm. The rate is approximately 80 beats per minute. There is ST segment elevation in lead I. In addition, ST segment elevation is present in leads V2-V4. There are no reciprocal changes in the inferior wall leads. There are non specific ST segment changes (flattening) present in leads V5-V6.  The QRS axis is difficult to determine but the slightly positive complex in lead aVF and the positive complex in lead I put the mean vector at about 0 degrees, or within the physiologically "normal" range. (17 degrees according to the all knowing interpretation software..)
Incidentally, the QRS is decreased in amplitude. Low voltage QRS is concerning in the setting of patients who present in extremis or with hypotension. Low voltages can indicate serious underlying conditions such as pericardial effusion and tamponade. The patient is hypertensive and a bit tachypneic (RR>18). Remain vigilant for the development of pulmonary edema.



The distribution of the ST segment elevation suggests an acute infarction of the heart's septal and anterior walls. Lead I STE may indicate some lateral involement as well. Patients with anterior wall STEMI are at risk for the development of dysrhythmia and congestive heart failure. The routine administration of morphine sulfate, contrary to many established protocols, has not been associated with improved patient outcome. Administer aspirin, nitroglycerin, and transport to a facility capable of percutaneous coronary intervention.

As mentioned in previous cases, ST segment elevation in leads aVR or even V1 may be predictive of a left main coronary artery occlusion. The anterior wall injury pattern, as seen in this ECG, may be due to acute occlusion of the left anterior descending artery or one of its branches. It is challenging to reliably identify the culprit lesion; anatomy is always better defined during the cardiac catheterizaton.

Final ECG Interpretation:
Sinus rhythm, rate of 90, anterior wall STEMI. Probable acute lateral wall ischemia  Low voltage QRS.  

A Serial Case

An elderly male patient is transported to the emergency department following a syncopal episode. The patient reported feeling lightheaded, and experienced two witnessed syncopal episodes lasting for several minutes. Symptoms were made worse when standing up. The patient denied chest pain and reported some mild dyspnea. The patient had been in his usual state of health. The patient's medical history is significant for a tibial fracture several months prior.

Vitals:

Afebrile

BP: 72/P

P: 100

R: 24

Sp02: 92%, poor waveform, on NRB

Physical exam:

Pt is diaphoretic and alert.

Lungs are clear bilaterally.

The patient's abdomen is soft and non tender.
No evidence of lower extremity edema.

(Prehospital) 12 lead ECG:

Upon arrival at the hospital, large bore IV access was secured. A FAST (Focused Assessment with Sonography for Trauma) exam revealed no obvious free fluid and no obvious pericardial effusion. The abdominal aorta appeared grossly normal. The patient remained alert and responded to a bolus of IV crystalloid. A repeat ECG was obtained following another pre-syncopal event in the emergency department.

12 Lead ECG Interpretation and Discussion

On the repeat ECG, a sinus rhythm is present. The electrical axis is physiologic. Artifact interferes with the tracing in the inferior limb leads. ST segment elevation is present in aVR, V1, and V2. The ST segments appear horizontal in shape. That particular morphology is concerning for ischemia. While some mild ST segment depression is present in lead I, there are no clear cut reciprocal changes. The evolving changes suggest a septal wall myocardial infarction.

Final Interpretation

Sinus tachycardia, septal ST segment elevation myocardial infarction

(WRONG!)

Case Conclusion

The patient was transported emergently to the cardiac catheterization lab. The patient's coronary arteries were CLEAN and without evidence of disease. An emergent echocardiogram showed a severely dilated right ventricle with concurrent diastolic dysfunction. The clean coronary arteries and echocardiograpghic findings combined point to a massive pulmonary embolism as the cause of the patient's symptoms. Another subtle clue to this diagnosis was the hypoxia that persisted with high flow oxygen administration.

Though not all that elevates is a STEMI, field providers should nevertheless focus on identifying worrisome ST segment changes. The patient's initial ECG was somewhat non-specific. Though close inspection can reveal some slight ST segment elevation of less than 1mm in aVR and V1, it certainly did not meet standardized criteria for STEMI. The second ECG, however, represents a clear-cut evolution. ST segments have become more pronounced (elevated) in the septal leads. The increase in elevation combined with the horizontal plateau of the ST segments in leads V1-V2 suggest an evolving myocardial infarction- or an alternative diagnosis.

The patient presented with a syncopal episode and profound hypotension. Any number of emergent medical conditions can present with those complaints. Pulmonary embolism, internal bleeding, and aortic dissection must be considered in the initial assessment of the hypotensive patient. Unfortunately, there are no "classic" electrocardiographic findings associated with a large PE. That said, the following features can be seen in the setting of a pulmonary embolism.

PULMONARY EMBOLISM ECG FINDINGS

• Sinus tachycardia
• Right bundle branch block or incomplete right bundle branch block
• Deep S wave in lead I, Q wave in lead III, and an interveted T wave in lead III (S1, Q3, T3)
• T wave inversions
• Right axis deviation
• ST segment deviation (depression and elevation)

Sinus tachycardia and right bundle branch block may suggest "heart strain." These are electrical manifestations caused by the right ventricle that is pumping against a greatly increased pulmonary resistance.

You make the call!

This patient presented to an outside hospital for palpitations following the use of a routine anti-asthma medication. The patient reported chest discomfort and some associated shortness of breath shortly after medication administration. The patient's vital signs remain stable, and her lung sounds were clear. The remainder of the physical examination was unremarkable. An emergency physician obtained a routine ECG. The patient's vital signs were stable and the physical examination was unremarkable.  

The patient was transferred to a tertiary care facility for cardiac catheterization.

1. What's your interpretation of the 12 lead?
2. What are some diagnostic considerations?

12 lead ECG Interpretation
Sinus rhythm, rate approximately 70, diffuse ST segment elevation
There is a baseline sinus rhythm. Widespread ST segment elevation is present in leads I, aVL, II, III, aVF, and in the anterior-lateral precordial leads. The R waves and ST segment depression in leads V1 and V2 are consistent with posterior wall ischemia. The ST segments themselves are mostly convex. The convexity of the ST segment is also suggestive of ischemia. Infarction of the heart's anterior, inferior, lateral, and posterior walls could conceivably produce the diffuse ST segment changes seen in this ECG.

12 lead ECG Discussion and Case Resolution
There are several considerations to bear in mind when looking at diffuse ST segment elevations:
1. Massive myocardial infarction
2. Pericarditis
3. Ventricular wall aneurysm 
4. Coronary vasospasm

The patient's clinical picture (and overall well appearance) is not consistent with the diagnosis of a massive myocardial infarction.

The ST elevations in pericarditis are usually more CONCAVE in appearance. Reciprocal changes are never associated with pericarditis. PR segment depression is also present in pericarditis.

Ventricular wall aneurysm usually presents electrocardiographically with Q waves and diffuse ST segment elevations. There may be a loss of R wave progression across the precordial leads.

There was no lesion amenable to intervention at the time of angiography. The patient's echocardiogram revealed a preserved ejection fraction with some mild, but diffuse, hypokinesis. The patient was diagnosed with coronary artery vasospasm.