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Pathological Q waves

Recent M.I.

Wed, 04/20/2016 - 23:07 -- Dawn

This ECG is from a 54-year-old woman who had an M.I. one week prior to this tracing.  She did not receive interventional treatment, as it was not available where she lived when this happened years ago.  Her ECG shows the signs of healing injury, as well as probable permanent damage. 

Where was this M.I.?      The affected leads are all of the precordial leads (V1 through V6), as well as I and aVL.   The precordial leads reflect the anterior and low lateral walls of the heart, and Leads I and aVL show us the high lateral wall.  This area is perfused by the left coronary artery, and she had a proximal lesion. 

What ST and T wave changes are present?    All of the leads listed above show a flattening of the ST segments.  While they are no longer elevated (the acute injury is over), they are flat and almost convex upward.  This shape is usually abnormal, and it has persisted even though the acute injury is subsiding.  The T waves in the anterolateral leads are all inverted.  This represents reperfusion of the injured tissue.  Whether the offending clot is removed by invasive procedure, thrombolytic drugs, or natural degradation, the tissue that is still alive will reperfuse. 

Inverted T waves in Lateral Wall

Tue, 11/10/2015 - 20:45 -- Dawn

This ECG was obtained from a 49-year-old man who was a patient in an Emergency Dept.  We do not know his presenting complaint, only that he had a history of insulin-dependent diabetes mellitus (IDDM).  It was noted by the donor of the ECG that the patient had no chest pain, no shortness of breath, and no other cardiac symptoms.  We do not know his hydration or electrolyte status.  There are quite a few interesting abnormalities on this ECG, and the exact interpretation would, of course, depend upon the patient's clinical status.  It would definitely help to be there!

First, we note a sinus tachycardia at a rate of 118 bpm.  This could be due to very many causes, including but not limited to:  dehydration, pain, anxiety, high or low blood glucose, fever, or CHF.  The PR and QT intervals are within normal limits.  The QRS complexes are narrow.  The axis is normal at 0 degrees.  The QRS voltage in the lateral leads is on the high side of normal, but we do not know this patient's body type.  Voltage as read by the ECG can be influenced by a thin chest (making voltage look larger) or a large chest (making voltage lower).

There are T wave abnormalities in the lateral leads:  I, aVL, V5 and V6.  The T waves are inverted, which can have many meanings.  However, when inverted T waves are in the lateral leads, as opposed to the inferior or right chest leads, it is often a sign of ischemia.  The flat, horizontal ST segments can also signify coronary artery disease (CAD).  This patient denied cardiac symptoms, but his age and history of IDDM make it probably that CAD is a factor.  The leads with T wave inversion also have a small amount of ST segment depression.  The right precordial leads, V1 and V2, have a small amount of ST elevation,  This possibly represents a reciprocal change to the ST depression in V5 and V6.

Because we are not at the bedside of this patient, there are many details we do not know.  But these inverted T waves could be ischemic T waves, and this requires that the patient be further evaluated.

As always, we welcome comments, as this ECG probably has more to say!

 

REFERENCES:  Dr. Ken Grauer,  Life In The Fast Lane, World Journal of Cardiology 

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

Fri, 08/29/2014 - 17:15 -- Dawn

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.

Acute Anterior-Lateral Wall M.I.

Fri, 04/25/2014 - 14:01 -- Dawn

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.

Previous Inferior Wall M.I. and Left Axis Deviaton

Fri, 01/17/2014 - 21:39 -- Dawn

If you are teaching frontal plane axis to your students, you will need to teach them HOW to determine the axis - usually beginning with the QRS axis and then adding the P and T waves.  But, you also need to teach them WHY we measure axis, to provide relevance to something that may seem challenging to beginners.  There are many ECG interpretations that rely heavily or are dependent upon the determination of the axis.  

This ECG is a great example of left axis deviation.  The cause is readily discernible, if your students know the ECG signs of myocardial infarction. This patient had an inferior wall M.I. in the distant past, and now has pathological Q waves in Leads II, III, and aVF.  Pathological Q waves in related leads in a patient with history of M.I. are a sign of necrosis, or permanent damage, in that part of the heart.  The inferior wall has lost an extensive amount of tissue, which is now electrically inactive as well as mechanically inactive.  (You may also find it helpful to show students videos of ventriculograms showing normal LV function and hypokinesis of the LV due to M.I.)  Because of the loss of electrical activity in the inferior wall, the "mean" electrical direction (or axis) is AWAY from the inferior wall.  That is, the electricity travels AWAY from II, III, and aVF and TOWARD I and aVL.

Many of the blogs and webpages listed in our "Favorites" address the subject of axis determination.  Here is one from Cardio Rhythms Online if you would like a review.

 

 

 

Recent Anterior-Septal Wall M.I. With Right Bundle Branch Block

Thu, 04/18/2013 - 22:17 -- Dawn

This is an ECG from a 95 year old man who was recovering from an anterior-septal wall M.I.  Other clinical data for this patient has been lost, except that he suffered a new right bundle branch block during this M.I.  The ECG shows pathological Q waves in V1, V2, and V3, consistent with permanent damage (necrosis) in the anterior septal wall.  The ST segments in those leads are coved upward.  Even though the J points are not elevated, this ST segment shape suggests recent injury.  The classic RBBB pattern is present:  wide QRS, rSR' pattern in V1, and wide little s waves in I and V6.  It is not known why the overall voltage is low in this patient.

Lateral Ischemia and Previous MI In a Patient With Chest Pain

Mon, 01/09/2012 - 22:48 -- Dawn

During our summer break, we are reprising a few of the best ECGs from our archives, to give you a chance to comment or to ask questions.

This ECG was taken from a 52 year old man who was complaining of chest pain, with a history of severe multi-vessel disease. He has a history of M.I. and states he has five coronary stents.

His pain was partially relieved by Ntg., and he was given aspirin in the field, and then IV Ntg., Integrelin, and morphine before being sent to the cath lab. This ECG shows T wave inversions with coved upward ST segments, but no ST elevation in the lateral leads: I and aVL, and the anterior-lateral leads, V3 through V6. This represents the territory covered by the left coronary artery, and points to a lesion in the proximal portion of the artery. Also in this ECG are pathological Q waves in right side leads, III, V1 and V2.

In the cath lab, he was discovered to have a ruptured plaque in the proximal LAD, with some blood getting through a very narrow channel. He was referred for coronary artery bypass surgery the next day.

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