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Medical Forum / General / General / March 2004Q wave in III
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 http://www.gpnotebook.com/simplepage.cfm?ID=275447887 Larry > Is a Q wave in lead III considered a normal finding, > or would it suggest a previous MI. [quoted text clipped - 5 lines] > > Marty > Is a Q wave in lead III considered a normal finding, > or would it suggest a previous MI. The latter. > 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. > Thanks, You are welcome, Marty. Servant to the humblest person in the universe, Andrew -- Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/ ** Who is the humblest person in the universe? http://makeashorterlink.com/?W1F522557 What is all this about? http://makeashorterlink.com/?J2DB148A7 Is this spam? http://makeashorterlink.com/?N69721867 >>Is a Q wave in lead III considered a normal finding, >>or would it suggest a previous MI. [quoted text clipped - 17 lines] > > Andrew Are you really suggesting that an isolated Q in lead III is more likely to be an MI than a normal variant?  SignatureDavid Rind drind@caregroup.harvard.edu Good question. That's not what this source seems to indicate: http://www.gpnotebook.com/simplepage.cfm?ID=275447887 Larry >>> Is a Q wave in lead III considered a normal finding, >>> or would it suggest a previous MI. [quoted text clipped - 20 lines] > Are you really suggesting that an isolated Q in lead III > is more likely to be an MI than a normal variant? > Good question. That's not what this source seems to indicate: > > http://www.gpnotebook.com/simplepage.cfm?ID=275447887 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 -- Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/ ** Who is the humblest person in the universe? http://makeashorterlink.com/?W1F522557 What is all this about? http://makeashorterlink.com/?J2DB148A7 Is this spam? http://makeashorterlink.com/?N69721867 > >>Is a Q wave in lead III considered a normal finding, > >>or would it suggest a previous MI. [quoted text clipped - 17 lines] > 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 http://www.heartmdphd.com/ ** Who is the humblest person in the universe? http://makeashorterlink.com/?W1F522557 What is all this about? http://makeashorterlink.com/?J2DB148A7 Is this spam? http://makeashorterlink.com/?N69721867 >>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? SignatureDavid Rind drind@caregroup.harvard.edu > >>Are you really suggesting that an isolated Q in lead III > >>is more likely to be an MI than a normal variant? [quoted text clipped - 5 lines] > 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. > 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. > 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. > but that you personally worry that someone > with a Q in III might have had an MI Why would this be personal, David? > 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 -- Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/ ** Who is the humblest person in the universe? http://makeashorterlink.com/?W1F522557 What is all this about? http://makeashorterlink.com/?J2DB148A7 Is this spam? http://makeashorterlink.com/?N69721867 >>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. >>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? > 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? >>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 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. SignatureDavid Rind drind@caregroup.harvard.edu > >>So perhaps a better answer to the original poster might have > >>been that it is a normal variant, [quoted text clipped - 15 lines] > 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 > >>but that you personally worry that someone > >>with a Q in III might have had an MI [quoted text clipped - 3 lines] > 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. > > I base my assessment of what tests are needed for the appropriate > > diagnosis and treatment of a patient on the entire clinical picture, [quoted text clipped - 4 lines] > 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 -- Dr. Andrew B. Chung, MD/PhD Board-Certified Cardiologist http://www.heartmdphd.com/ ** Who is the humblest person in the universe? http://makeashorterlink.com/?W1F522557 What is all this about? http://makeashorterlink.com/?J2DB148A7 Is this spam? http://makeashorterlink.com/?N69721867 >>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: >>Is a Q wave in lead III considered a normal finding, >>> or would it suggest a previous MI. [quoted text clipped - 7 lines] > 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: http://www.med.umich.edu/lrc/ecgoftheweek/cases/case01/answer01.html SignatureDavid Rind drind@caregroup.harvard.edu > >>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) [quoted text clipped - 20 lines] > 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. > 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. > 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. > From everything I've > ever seen, it is an unusual position. For a more standard take on > the subject look at: > http://www.med.umich.edu/lrc/ecgoftheweek/cases/case01/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 http://www.heartmdphd.com/ ** Who is the humblest person in the universe? http://makeashorterlink.com/?W1F522557 What is all this about? http://makeashorterlink.com/?J2DB148A7 Is this spam? http://makeashorterlink.com/?N69721867 > 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. >> 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) [quoted text clipped - 5 lines] > 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: http://www.med.umich.edu/lrc/ecgoftheweek/cases/case01/answer01.html SignatureDavid Rind drind@caregroup.harvard.edu >>> 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) [quoted text clipped - 10 lines] > 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 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 [quoted text clipped - 6 lines] > 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. SignatureDavid Rind drind@caregroup.harvard.edu |
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