Q wave in III

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Larry

Martin Braff said:

Is a Q wave in lead III considered a normal finding, or
would it suggest a previous MI.

If it would indicate an MI, in which area of the heart
would the MI have occurred?

Thanks,

Marty

Martin Braff said:

Is a Q wave in lead III considered a normal finding, or
would it suggest a previous MI.

The latter.

Quoted message said:

If it would indicate an MI, in which area of the heart
would the MI have occurred?

Inferiorly. However, when there are Q waves only in one
lead, the MI should be either confirmed or refuted by an
echocardiogram, imho.

Quoted message said:

Thanks,

You are welcome, Marty.

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Andrew

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Dr. Andrew B. Chung said:

Martin Braff said:

Is a Q wave in lead III considered a normal finding, or
would it suggest a previous MI.

The latter.

Quoted message said:

If it would indicate an MI, in which area of the heart
would the MI have occurred?

Inferiorly. However, when there are Q waves only in one
lead, the MI should be either confirmed or refuted by an
echocardiogram, imho.

Quoted message said:

Thanks,

You are welcome, Marty.

Servant to the humblest person in the universe,

Andrew

Are you really suggesting that an isolated Q in lead III is
more likely to be an MI than a normal variant?

--
David Rind [email hidden]

Good question. That's not what this source seems to indicate:

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Larry

David Rind said:

Dr. Andrew B. Chung said:

Martin Braff said:

Is a Q wave in lead III considered a normal finding, or
would it suggest a previous MI.

The latter.

Quoted message said:

If it would indicate an MI, in which area of the heart
would the MI have occurred?

Inferiorly. However, when there are Q waves only in one
lead, the MI should be either confirmed or refuted by an
echocardiogram, imho.

Quoted message said:

Thanks,

You are welcome, Marty.

Servant to the humblest person in the universe,

Andrew

Are you really suggesting that an isolated Q in lead III
is more likely to be an MI than a normal variant?

David Rind said:

Dr. Andrew B. Chung said:

Martin Braff said:

Is a Q wave in lead III considered a normal finding, or
would it suggest a previous MI.

The latter.

Quoted message said:

If it would indicate an MI, in which area of the heart
would the MI have occurred?

Inferiorly. However, when there are Q waves only in one
lead, the MI should be either confirmed or refuted by an
echocardiogram, imho.

Quoted message said:

Thanks,

You are welcome, Marty.

Servant to the humblest person in the universe,

Andrew

Are you really suggesting that an isolated Q in lead III
is more likely to be an MI than a normal variant?

No, David.

However, it does suggest the possibility.

Servant to the humblest person in the universe,

Andrew

--
Dr. Andrew B. Chung, MD/PhD
Board-Certified Cardiologist
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Larry said:

Good question. That's not what this source seems to
indicate:

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Depends on the "size" of the Q wave (and whether there is
concomitant T wave abnormalities), Larry.

Servant to the humblest person in the universe,

Andrew

--
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Board-Certified Cardiologist
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Dr. Andrew B. Chung said:

David Rind said:

Are you really suggesting that an isolated Q in lead III
is more likely to be an MI than a normal variant?

No, David.

However, it does suggest the possibility.

So perhaps a better answer to the original poster might have
been that it is a normal variant, that most people with an
isolated Q in III have not had an MI, that it is not
considered an indication of an MI, but that you personally
worry that someone with a Q in III might have had an MI and
so to be absolutely sure like to obtain an echocardiogram in
such patients even though that is not standard of care?

--
David Rind [email hidden]

David Rind said:

Dr. Andrew B. Chung said:

David Rind said:

Are you really suggesting that an isolated Q in lead III
is more likely to be an MI than a normal variant?

No, David.

However, it does suggest the possibility.

So perhaps a better answer to the original poster might
have been that it is a normal variant,

Wrong answers are not better answers, David.

Quoted message said:

that most people with an isolated Q in III have not
had an MI,

Most people with isolated *small* Qs in III have not
had an MI.

Quoted message said:

that it is not considered an indication of an MI,

If there are *large* Qs in III, one should hesitate in
calling the EKG a normal variant.

Quoted message said:

but that you personally worry that someone with a Q in III
might have had an MI

Why would this be personal, David?

Quoted message said:

and so to be absolutely sure like to obtain an
echocardiogram in such patients even though that is not
standard of care?

I base my assessment of what tests are needed for the
appropriate diagnosis and treatment of a patient on the
entire clinical picture, which for me includes the history,
the physical exam, the EKG, blood tests +/- a chest X-ray.

Are you trying to say that you practice differently, David?

(The gift of truth discernment at work :-)

Servant to the humblest person in the universe,

Andrew

--
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Board-Certified Cardiologist
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Dr. Andrew B. Chung said:

Quoted message said:

So perhaps a better answer to the original poster might
have been that it is a normal variant,

Wrong answers are not better answers, David.

Yes, that was indeed my objection to your answer.

Quoted message said:

Quoted message said:

that most people with an isolated Q in III have not
had an MI,

Most people with isolated *small* Qs in III have not
had an MI.

True. Have most people with large Qs in III had an MI?

Quoted message said:

If there are *large* Qs in III, one should hesitate in
calling the EKG a normal variant.

You can hesitate if you like. Again, have most people with
large Qs in III had an MI?

Quoted message said:

Quoted message said:

but that you personally worry that someone with a Q in III
might have had an MI

Why would this be personal, David?

Because most people don't worry about an MI in someone with
an isolated Q in III and you seem to.

Quoted message said:

I base my assessment of what tests are needed for the
appropriate diagnosis and treatment of a patient on the
entire clinical picture, which for me includes the
history, the physical exam, the EKG, blood tests +/- a
chest X-ray.

That seems like a fine choice. And yet you told a poster on
Usenet who gave you a single fact (that an EKG showed an
isolated Q in III) that you believe an echo is indicated to
exclude an MI.

--
David Rind [email hidden]

David Rind said:

Dr. Andrew B. Chung said:

Quoted message said:

So perhaps a better answer to the original poster might
have been that it is a normal variant,

Wrong answers are not better answers, David.

Yes, that was indeed my objection to your answer.

Quoted message said:

Quoted message said:

that most people with an isolated Q in III have not had
an MI,

Most people with isolated *small* Qs in III have not had
an MI.

True. Have most people with large Qs in III had an MI?

Quoted message said:

If there are *large* Qs in III, one should hesitate in
calling the EKG a normal variant.

You can hesitate if you like. Again, have most people with
large Qs in III had an MI?

Ime, isolated large Qs in III are pathological more
often than not.

YMMV

Quoted message said:

Quoted message said:

Quoted message said:

but that you personally worry that someone with a Q in
III might have had an MI

Why would this be personal, David?

Because most people don't worry about an MI in someone
with an isolated Q in III and you seem to.

I don't worry, David.

Quoted message said:

Quoted message said:

I base my assessment of what tests are needed for the
appropriate diagnosis and treatment of a patient on the
entire clinical picture, which for me includes the
history, the physical exam, the EKG, blood tests +/- a
chest X-ray.

That seems like a fine choice. And yet you told a poster
on Usenet who gave you a single fact (that an EKG showed
an isolated Q in III) that you believe an echo is
indicated to exclude an MI.

Would suggest you reread my post, David.

Servant to the humblest person in the universe,

Andrew

--
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Board-Certified Cardiologist
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David Rind said:

That seems like a fine choice. And yet you told a poster
on Usenet who gave you a single fact (that an EKG showed
an isolated Q in III) that you believe an echo is
indicated to exclude an MI.

Wouldn't something like a Cardiolyte be a better test for
excluding a prior MI? Wall-motion abnormalities on echoes
are extremely subjective anyway, and a small scar could
easily be impossible to ascertain. If one were to see a
fixed defect on a Cardiolyte, that would be more
confirmatory, and a Cardiolyte would also help rule out
ongoing ischemia.

Dr. Andrew B. Chung said:

David Rind said:

That seems like a fine choice. And yet you told a poster
on Usenet who gave you a single fact (that an EKG showed
an isolated Q in III) that you believe an echo is
indicated to exclude an MI.

Would suggest you reread my post, David.

Okay, I've reread it:

Quoted message said:

Quoted message said:

Is a Q wave in lead III considered a normal finding,

Quoted message said:

or would it suggest a previous MI.

The latter.

Quoted message said:

Quoted message said:

If it would indicate an MI, in which area of the heart
would the MI have occurred?

Inferiorly. However, when there are Q waves only in one
lead, the MI should be either confirmed or refuted by an
echocardiogram, imho.

Hard for me to see how the original poster could not
conclude from this:

1) An isolated Q in III is generally an abnormal finding
that suggests an MI.
2) Someone with an isolated Q in III should have an
echocardiogram to determine whether or not they had
really had an MI.

I believe you are just wrong about answer 1, and answer 2
(as I suggested earlier) reflects your personal willingness
to live with uncertainty in a situation like this. From
everything I've ever seen, it is an unusual position. For a
more standard take on the subject look at: med.u-med.u-Open ↗
mich.edu/lrc/ecgoftheweek/cases/case01/answer01.html

--
David Rind [email hidden]

anon said:

David Rind said:

That seems like a fine choice. And yet you told a poster
on Usenet who gave you a single fact (that an EKG showed
an isolated Q in III) that you believe an echo is
indicated to exclude an MI.

Wouldn't something like a Cardiolyte be a better test for
excluding a prior MI? Wall-motion abnormalities on echoes
are extremely subjective anyway, and a small scar could
easily be impossible to ascertain. If one were to see a
fixed defect on a Cardiolyte, that would be more
confirmatory, and a Cardiolyte would also help rule out
ongoing ischemia.

I don't think I'm willing to take a position on the "right"
test to perform in a situation that I don't think normally
requires additional testing....

As posted elsewhere in this thread, take a look at the
answer given at: med.umich.edumed.umich.eduOpen ↗
cases/case01/answer01.html

--
David Rind [email hidden]

David Rind said:

Dr. Andrew B. Chung said:

David Rind said:

That seems like a fine choice. And yet you told a poster
on Usenet who gave you a single fact (that an EKG showed
an isolated Q in III) that you believe an echo is
indicated to exclude an MI.

Would suggest you reread my post, David.

Okay, I've reread it:

Quoted message said:

Quoted message said:

Is a Q wave in lead III considered a normal finding,
> or would it suggest a previous MI.

The latter.

Quoted message said:

> If it would indicate an MI, in which area of the heart
> would the MI have occurred?

Inferiorly. However, when there are Q waves only in one
lead, the MI should be either confirmed or refuted by an
echocardiogram, imho.

Hard for me to see how the original poster could not
conclude from this:

1) An isolated Q in III is generally an abnormal finding
that suggests an MI.

It seems to me that the OP has already had reached (1)
either on his own or from someone else. Otherwise he would
not have posted his questions as he did (especially the follow-
up question). I simply affirmed that a Q wave in III can
suggest an MI without getting into its specificity.

Quoted message said:

2) Someone with an isolated Q in III should have an
echocardiogram to determine whether or not they had
really had an MI.

I believe you are just wrong about answer 1,

You are wrong about answer 1 being my answer. Rather, answer
1 is *your* interpretation of my answer.

My answer to Marty was and is correct. You interpretation of
my answer is incorrect.

Truth is simple.

Quoted message said:

and answer 2 (as I suggested earlier) reflects your
personal willingness to live with uncertainty in a
situation like this.

Again, that would be your incorrect interpretation.

Quoted message said:

From everything I've ever seen, it is an unusual
position. For a more standard take on the subject look
at: med.umich.educaseOpen ↗
01/answer01.html

Yes, the *small* Q in III in your example should be read as
normal variant (probably from a "turned" heart).

Is is *small* in duration (less than 40 msec) and is smaller
in amplitude relative to the R wave.

Moreover the dramatic variation in voltage amplitude of this
*small* Q wave with respiration is the important clue that
it arises from a "turned" heart rather than scarring of the
inferior wall. Note that by the 2nd QRS complex in III, the
*small* Q wave is almost as deep as the R wave is tall only
to shrink by the 3rd and 4th QRS complex.

For the EKG sophisticates out there, the "ventricular
gradient" based on the principles of vector
electrocardiography as taught by one of my mentors
(J. Willis Hurst, MD) is normal here further lending support
to the Q wave in III with the T wave inversion being a
normal variant.

Servant to the humblest person in the universe,

Andrew

--
Dr. Andrew B. Chung, MD/PhD
Board-Certified Cardiologist
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David Rind said:

anon said:

David Rind said:

That seems like a fine choice. And yet you told a poster
on Usenet who gave you a single fact (that an EKG showed
an isolated Q in III) that you believe an echo is
indicated to exclude an MI.

Wouldn't something like a Cardiolyte be a better test for
excluding a prior MI? Wall-motion abnormalities on echoes
are extremely subjective anyway, and a small scar could
easily be impossible to ascertain. If one were to see a
fixed defect on a Cardiolyte, that would be more
confirmatory, and a Cardiolyte would also help rule out
ongoing ischemia.

I don't think I'm willing to take a position on the
"right" test to perform in a situation that I don't think
normally requires additional testing....

Well, my point wasn't that an isolated Q wave in lead III
would require further testing (FWIW, I agree with you that
it's a normal variant). The previous poster's suggestion
that an echocardiogram would be the test of choice in
ascertaining whether or not an individual had previously
suffered a subclinical myocardial infarction is, I think,
questionable at best.

anon said:

David Rind said:

I don't think I'm willing to take a position on the
"right" test to perform in a situation that I don't think
normally requires additional testing....

Well, my point wasn't that an isolated Q wave in lead III
would require further testing (FWIW, I agree with you that
it's a normal variant). The previous poster's suggestion
that an echocardiogram would be the test of choice in
ascertaining whether or not an individual had previously
suffered a subclinical myocardial infarction is, I think,
questionable at best.

I understood, but don't think it's that easy a question to
answer given the lack of indication for the test. For
instance, if someone had had a Q-wave inferior MI, I would
guess that either test would probably demonstrate the fact,
and the choice of test would have more to do with whether
you were worried about ongoing ischmemia or wanted a good
look at cardiac and valvular function.

If they'd had a non Q-MI, I think you are right to worry
that an echo might not show a wall motion abnormality
although in many people it would show such an abnormality.

I don't know how to think about the issue in someone who has
a normal variant EKG with an isolated Q in III. Since I'm
not worried by the EKG, what is the right test to exclude
that the Q wave is due to a prior MI? Is an isolated Q in
III, if it reflects an MI, supposed to be more likely to be
small or to be larger/transmural?

So while I disagree with the implications of Dr. Chung's
recommendation for testing, I have trouble saying he is
picking the "wrong" test given that he personally believes
additional testing is warranted. Whatever test will leave
him feeling reassured seems good for this purpose.

--
David Rind [email hidden]