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Teaching Series: Anterior Wall M.I.

A series of ECGs can be a valuable addition to any teacher's collection.  This series follows a 75-year-old woman through three days, during which she experienced an acute anterior wall M.I., a catheterization with angioplasty and stents placement.

In the first ECG, taken at 4:09 am, the patient has presented to the Emergency Dept. with a complaint of chest pain. (Other details are no longer available).  Although there is some baseline artifact, it appears that the rhythm is sinus rhythm with one PAC (7th beat).  There is subtle but measurable ST elevation in V1, V2, and V3 (anterior-septal leads).  The shape of the STE in V1 is noticeably coved upward.  Even aVR has some STE, with coving.  There is equally subtle ST depression in Leads II, III, and aVF (inferior leads).  Fortunately, there are no pathological Q waves at this point, which would be an indication of necrotic tissue in the area of the M.I. (anterior-septal wall).

The patient was taken to the cath lab, where it was found that she had a 100% mid-left anterior descending artery occlusion, which was opened and stented.  She also was found to have widespread coronary artery disease, with the left circumflex artery 25% occluded (stented), the right coronary artery (which was dominant) proximately occluded 50% and stented, and the posterior descending artery 75% occluded (stented).

The second ECG, taken at 6:29 the same morning, after the cath procedure, shows some ST elevation with coving remaining in V1 through V3, and also aVR, but now with the loss of R waves in V1 and V2 and loss of R wave voltage in V3.  This represents the formation of pathological Q waves, and can be a permanent change in many cases.

The third ECG, taken two days later in the cardiac step-down unit, shows improvement, and progression toward healing.  The ST segments are still shaped in a slightly coved-upward shape, but they are less elevated.  The R waves have returned.  The T waves in V1-V3 are inverted.  The deeply inverted T waves of V2 and V3, especially, and classic for ischemia, and we even see the "ischemic zone" extending across the anterior-lateral wall, including V4 through V6 and Leads I and aVL.

The patient did very well to discharge, and we don't have followup after that.

 

 

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Inferior-lateral and Posterior Wall M.I.

This is from a Cardiac Alert patient, with chest pain, in the Emergency Department.  The ECG shows ST elevation in the inferior leads (II, III, and aVF), and in the low lateral leads (V5 and V6).  There is reciprocal depression in V1 and V2, indicating injury in the posterior wall.  One could argue that "inferior" is just the term we use for the lower part of the posterior wall - the part that faces the floor in a standing person.  So, "inferior-posterior" reflects a more proximal occlusion of the culprit artery.

The high lateral wall is represented by I and aVL.  These leads would usually show marked reciprocal ST depression when II, III, and aVF have elevation.  However, in this ECG, aVL is depressed, but not as much as expected, and Lead I almost looks elevated!  This could represent even more extensive lateral wall involvement.  A dominant right coronary artery could be the culprit, but it seems more likely that a dominant circumflex artery is to blame, as it could perfuse the entire lateral wall before joining with the posterior descending artery and perfusing the inferior wall.  Unfortunately, we do not have the cath results on this patient.

The ST elevation in this ECG has the classic appearance of acute M.I., and will be interesting to both beginner and advanced students.

Often, one ECG can provide a wealth of teaching opportunities, no matter what the level of your students.  For the student learning to monitor the rate and rhythm, you might crop this image to only show the Lead II rhythm strip at the bottom, for a good example of normal sinus rhythm with a borderline PRI of .20 sec.   For the student learning about ST elevation M.I., this is a good example of inferior-posterior and lateral injury.  Leads aVL, V1 and V2 demonstrate reciprocal ST depression.  When an observant student notices the slight ST elevation in V6, a discussion of coronary artery distribution can occur.  

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Extensive Anterior-lateral M.I. With Right Bundle Branch Block

This ECG depicts an extensive and ultimately, fatal, injury.  There is marked ST segment elevation in Leads V2 through V6 (anterior wall).  There is also ST elevation in Leads I and aVL (high lateral wall).  The ST elevation in aVR is indicative of a very proximal lesion in the left coronary artery, which supplies the anterior wall, including the anterior portion of the septum, the high lateral wall, and, in this case, the low lateral wall.  The inferior leads, II, III, and aVF, show reciprocal ST depression.

This is an old ECG - the computer readings of the rate and intervals is lost, as is the grid.  But the rate here appears to be about 80 bpm and the QRS is widened.  There is a right bundle branch block ECG pattern, which is not surprising given the extensive septal damage.  Normally, the criteria for RBBB on the ECG includes an rSR' pattern in V1 (seen here) and a small, wide s wave in Leads I and V6.  This s wave is not seen here, presumably due to the effects of the ST elevation in those leads.

What matters clinically in a patient like this is not whether there is RBBB or another type of interventricular conduction delay. This patient needs immediate restoration of blood flow through the LCA and intensive medical/nursing care.  As mentioned before, this patient did not survive, in spite of being brought to a hospital.  We do not know the exact mechanism of death or treatment course in this case.

If you are teaching students to use multiple leads in assessing rhythm, this is a great example of how one or two leads can be very misleading.  I have used this ECG's V4 in an excercise illustrating this concept.  Shown V4, many people would call this "AIVR" or "V Tach".  Seen in context with the other leads, it is obvious that we are looking at ST elevation that is as high as the R wave.  Two leads are better than one, and twelve are better than two.

 

 

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Inferior Wall MI With Artifact

This ECG is taken from a 66-year-old man who presented to the Emergency Dept. with a complaint of chest pain.  The ECG shows clear signs of acute inferior wall MI:  ST segment elevation in Leads II, III, and aVF and reciprocal ST depression in Leads I and aVL.  In addition, there are reciprocal ST depressions in Leads V1, V2, and V3.  These indicate that the MI extends up the inferior wall into the area called by most clinicians the posterior wall.  When the injured area extends high enough from the inferior wall, it becomes visible to the anterior-septal leads as ST depression.  There is also a small ST elevation in Leads V5 and V6, the low lateral wall, indicating a common blood supply for the inferior and low lateral walls (usually the right coronary artery).  All of these findings make this a rather "typical" inferior wall MI.

Unfortunately, this ECG also has a significant amount of artifact.  The second, sixth, and tenth "beats"  appear to be  premature beats in Leads I and II.  However, it is important to remember that the four channels on this ECG are run simultaneously.  That is, any complex of significant voltage should show up four times.  The "premature" beats do not appear in Lead III, and do not affect the timing of the appearance of the next beat at all.  They also appear during moments of baseline disruption, indicating that they are not heartbeats, but simply artifact.

Why is this important?  Artifact makes the ECG hard to interpret accurately.  The ECG machine even had a difficult time, completely ignoring obvious P waves, and calling the rhythm "atrial fibrillation".  Every effort should be made to obtain the cleanest, most artifact-free ECG possible.

Additional note:  it can be very informative to do a right-sided ECG on an IWMI patient, or at least a V4Rt.  In fact, it is a protocol requirement in many EMS agencies.  Right ventricular infarction can change the hemodynamics of your patient, causing a need for fluid resuscitation. In fact, a drop in BP, such as that caused by nitroglycerin, can cause circulatory collapse.  Ntg should be given cautiously to RVMI patients.  Fortunately, IV fluids will seldom cause left heart overload in these patients.  A look at the right ventricle with V4Rt can be very helpful in deciding treatment options.

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Extensive Anterior Wall M.I. With Recent Inferior Wall M.I.

This 88-year-old woman was brought to the Emergency Department in cardiogenic shock.  Very little is known of her past medical history, but it was relayed to the EMS responders that she had been ill for about four days, when she became much worse.

This ECG shows a large, acute anterio-lateral wall M.I., as evidenced by the ST ELEVATIONS in V2 through V6, Leads I and aVL.  To make matters worse, there are PATHOLOGICAL Q WAVES in Leads V2 through V6.  Pathological Q waves indicate areas of necrosis.  Because the myocardium facing the positive electrode is not electrically active, we "see through" the dead tissue to the myocardium on the opposite side of the heart.  Pathological Q waves could be thought of as "reciprocal R waves".  This represents a great deal of dead myocardium, which will be akinetic - not moving.

To make matters worse, she has pathological Q waves in the INFERIOR WALL as well, in Leads II, III, and aVF.  Her ST segments in those leads are flattened and possibly slightly elevated, but not much.  There are no reciprocal ST depressions in I and aVL, because they are affected by the anterior - lateral wall M.I., and are elevated.

The accompanying photos show her left coronary artery angiogram indicating severe coronary artery disease and a "missing" left anterior descending artery.  This is due to a proximal lesion that occurred around the area of the first diagonal artery, cutting off blood flow to a very large part of her anterior-lateral wall.  The photo of the right coronary artery shows a very tight lesion which is allowing some blood to pass.  The Interventionalist felt that this represented a resolving 100% occlusion (remember, she had been sick for four days).  As the blood clot broke up, blood flowed again, lowering the ST segments.  Unfortunately, permanent damage had already been done, and she had Q waves in the inferior wall also.  This leaves very little of her heart beating, and it is easy to understand why she presented in shock.  She suffered cardiac arrests several times during the procedure, and was managed with a balloon pump and ventilator.

Unfortunately, this type of injury is not survivable, and she died in the CVICU a few hours after her procedure. She contributes to our education by demonstrating the cumulative effects of M.I., especially when permanent damage occurs.  For a look at her ventriculogram, to understand the devastating effects of these injuries, go to our You Tube channel.

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Acute Anterior-lateral M.I. With Right Bundle Branch Block and Left Posterior Fascicular Block

This ECG was obtained from a patient who suffered an occlusion of the left main coronary artery.  ST elevation is seen in Leads V1 through V6, as well as I and aVL.  This is an indicator that the circumflex artery is included in this M.I., and the occlusion is above the bifurcation of the LM and the circ.  The patient also has a right bundle branch block and a left posterior fascicular block.  This bi-fascicular block can be a dangerous complication of acute M.I., as two of the three main bundle branches are no longer functional.

The ECG shows typical ST depression, probably reciprocal to the elevation, in the inferior leads.

The right bundle branch block is diagnosed by the following criteria:  1) Wide QRS;  2) Supraventricular rhythm; and 3) rSR' pattern in V1 with Rs with a wide little s wave in Leads I and V6.

The left posterior fascicular block is diagnosed by right axis deviation and by ruling out other causes of right axis deviation.  In RAD, Lead III will have a taller positive ( R ) wave than Lead II, and a negative Lead I.

This type of occlusion is often called the "Widow Maker", and requires very rapid intervention to restore blood flow and prevent complicatons.  If there is good news, it is that there are no pathological Q waves, which would indicate necrosis, and this patient was taken quickly to a full-service cardiac center with interventional cath labs and open heart surgery available.

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ECG Teaching Series: ST Elevation M.I. With Atypical DeWinter T waves

This series shows the evolution of ECG changes in anterior wall M.I. secondary to occlusion of the proximal left anterior descending artery.  The patient is an 88-year-old woman with chest pain.  She was designated a "cardiac alert" from the field by paramedics.  Her proximal LAD was opened and stented in the cath lab.  We do not have follow-up information on her.

The first ECG in the series, titled "12-Lead 3", shows ST elevation at the J point in V1 through V3.  In addition, the T waves are "hyperacute" - tall, broad, and asymmetrical. This can be an early, transient sign of myocardial injury.  Slight reciprocal depressions are seen in the inferior leads.  Lead V4 has a T wave inversion that is out of place with the progression of the T waves in V3 and V5.  Lead placement may be to blame.  Hyperacute T waves in a patient with chest pain should be taken very seriously.

The second ECG, titled "12-Lead 4", shows continued elevation at the J point in Leads V1 through V3, with a lessening of T wave amplitude.  In addition, Lead aVL is showing some T wave changes. The T wave is biphasic, and may be about to become inverted.  This is not an improvement!  V1 through V3 show us the anterior-septal wall, and an M.I. here indicates occlusion in the LAD.  Leads I and aVL show the high lateral area of the anterior wall, and damage here is an indicator that the occlusion is proximal.

The third ECG, titled "12-Lead 5", shows a "maturing" of the ST segment elevation.  Even though there is some significant artifact, we can see that the ST segment in V1 is coved upward, and the ST segment in V2 is flat.  Both shapes are abnormal, and a sign of CAD.  The T waves have become less pronounced, but V2 looks as if the T wave may become inverted in the near future.  V3 looks improved in this image.

The patient's clinical symptoms did not improve during these ECG changes.  Hyperacute T waves are not a definitive sign of STEMI, but they provide a highly visible warning that may catch attention.  They definitely are an indication to run serial ECGs, as these paramedics did.

 

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Acute Anterior-Lateral Wall M.I.

This week's ECG is from a 47-year-old man who experienced a sudden onset of chest pain while mowing his lawn.  He went on to suffer a cardiac arrest and was resuscitated.  We do not have long-term followup on his outcome.

The experienced person will have no difficulty identifying a large acute antero-lateral wall M.I.  There are massive ST segment elevations in Leads V1 through V6, reflecting acute injury from the septal side of the anterior wall (patient's right) to the anterior-lateral wall (patient's left).  There are also ST elevations in Leads I and aVL, reflecting the high lateral wall.  This indicates, and was confirmed in the cath lab, that the lesion is proximal - at or above the bifurcation of the left anterior descending artery and the circumflex artery.  The ST depressions in the inferior wall leads (II, III, and aVF) likely represent reciprocal changes.  You will note that the ST depression in Lead III has a very similar shape to the ST elevation in Lead aVL.

More bad news for this patient is the presence of pathological Q waves in Leads V1 through V4, reflecting transmural death of the myocardial tissue.  This causes akinesis and poor left ventricular function.  In addition, it's not only muscle tissue that dies, but also electrical structures , such as bundle branches.   Papillary muscles can be infarcted, causing valve malfunction.  And remember, all patients who have ST elevation due to acute injury are vulnerable to ventricular tachycardia and ventricular fibrillation, due to re-entry mechanisms in injured tissue.   

This ECG will allow instructors to discuss with their students:

*  which leads reflect changes from which parts of the heart

*  what the ECG signs of acute M.I. are

*  the pathophysiology of pathological Q waves

*  the effect of damage to various parts of the heart on the patient's condition and symptoms

This "classic" M.I. pattern should be taught to all health care professionals who work in settings where ECG is used.

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Acute Inferior Wall M.I.

Another great ECG donated by Paramedic Eric Testerman.  This ECG is from a 66 year old man who was complaining of feeling dizzy, weak, and of having "minor" chest pain. He was extremely pale/ashen, had moderate cyanosis, and was very clammy and diaphoretic.  His initial heart rate was about 20 bpm.  His initial BP was 131/113 then, just before arrival at the hospital was 127/85. His HR increased to about 50 bpm (not shown). He was given 400 ml I.V. fluid, 324 gr of aspirin, and oxygen.  Transcutaneous defibrillator/pacemaker pads were applied. 

At the hospital, he was successfully treated with angioplasty for a 100% occlusion of the right coronary artery. The time from beginning of treatment to reperfusion of the artery was 47 minutes, which is very good! 

This is a "classic" inferior wall M.I., with ST elevation in leads II, III, and aVF. There are reciprocal ST depressions in I and aVL.  There are also ST depressions in V1 through V5.  This is generally considered to represent reciprocal ST changes in the posterior and lateral walls.There is a quite severe bradycardia, and the patient's skin showed signs of poor perfusion. Amazingly, the patient's BP stayed adequate during transport.  Bradycardia is common in inferior wall M.I. due to ischemic effects on the SA node and vagus nerve (sinus bradycardia) and the AV node (heart block).  In this case, the rhythm is sinus bradycardia.  The heart rate is in the 20's, and the PR interval is around .20 - .22 seconds. 

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Anterior Wall M.I.

A 78-year-old woman complained of nausea and diaphoresis.  Paramedics in the field found that her 12-lead ECG showed ST elevation in V1 through V4, aVL, and aVR.  The patient denied chest pain and also denied any cardiac history.  She did not want to be transported to the hospital, but thankfully, the paramedics understood that this was not an option, and convinced her to go.

She was taken to a cardiac facility as a STEMI Alert, was evaluated in the cath lab, and sent immediately to the O.R. for coronary artery bypass surgery.  She had severe multi-vessle disease and a lesion in her proximal left coronary artery.  No other details of the cath results are known.

Some important teaching points:

  • there is subtle ST elevation in V1 and V2, but the SHAPE of the ST segment is suspect, with flattening and almost a coving upward shape in V1.  Normal ST segments are convex downward, like a smile.
  • there is nearly complete loss of r waves in V1 and V2, and V3 and V4 have very small r waves.  This signals impending pathological Q waves, a sign of necrosis of the myocardium.  Necrotic muscle does not contract.
  • there is slight ST segment elevation in aVR.  Along with STE in V1, this is a marker for proximal LCA or left main occlusion.
  • the ST elevations in V3 and V4 are more pronounced, and easily meet STEMI guidelines:  currently 1.5 mm of elevation in V3 and 1 mm of elevation in V4 for a woman.
  • there are reciprocal ST depressions in II, III, and aVF - common in AWMI.
  • aVL has slight STE, along with inverted T waves. Somewhat surprisingly, there is no ST depression in Lead I.  This indicates high lateral wall injury.
  • the patient has a "hint" of the criteria for LVH:  her S wave in V3 + her R wave in V5 = about 33 mm, and there is depression in V6.  A stretch to call it "LVH", but possibly a sign of left ventricular strain because of the acute M.I.
  • there are atrial abnormalities suggested by the tall, peaked P waves in Lead II, the "M" shaped P waves in Lead III, and the inverted P waves in V1 and V2.  Possibly bi-atrial dilation and stress brought on by the M.I.?  An echocardiogram would be a better test for this.
  • the heart rate, at about 90 bpm, reflects NSR but is a cause of more stress on an overworked, injured heart.

This is a great teaching ECG, and we hope the Gurus out there will add even more interesting points to consider.

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