Difference between revisions of "Pathologic Q Waves"

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==Criteria for a previous myocardial infarction==
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{{Chapter|Myocardial Infarction}}
[[Image:PathoQMeasure.png|thumb| A pathological is Een pathologische golf (''x'') is dieper dan 1/3 van de hoogte van het QRS complex (''x+y'') en breder (''d'') dan 0,04 sec.]]
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[[Image:PathoQ.png|thumb| A pathologic Q wave]]
[[Image:PathoQ.png|thumb| Een pathologische Q golf]]
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Pathologic Q waves are a sign of '''previous [[Myocardial Infarction|myocardial infarction]]'''. They are the result of absence of electrical activity. A myocardial infarction can be thought of as an elecrical 'hole' as scar tissue is electrically dead and therefore results in pathologic Q waves. Pathologic Q waves are not an early sign of myocardial infarction, but '''generally take several hours to days to develop'''. Once pathologic Q waves have developed they rarely go away. However, if the myocardial infarction is reperfused early (e.g. as a result of percutaneous coronary intervention) stunned myocardial tissue can recover and pathologic Q waves disappear. In all other situations they '''usually persist indefinitely'''.
A '''previous myocardial infarction''' can be recognised by a '''pathologic Q wave'''. A pathologic Q wave is deeper than 1/3 the amplitude of the QRS complex and has a width of more than 0.04 sec. <cite>Alpert</cite>
 
  
'''Note''': Absence of pathologic Q waves does not exclude a myocardial infarction!
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The precise criteria for pathologic Q waves have been debated. Here we present the latest definition as accepted by the ESC and ACC.<cite>Thygesen</cite>
  
A pathologic Q wave  
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;Definition of a pathologic Q wave
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:Any Q-wave in leads V2–V3 ≥ 0.02 s or QS complex in leads V2 and V3
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:Q-wave ≥ 0.03 s and > 0.1 mV deep or QS complex in leads I, II, aVL, aVF, or V4–V6 in any two leads of a contiguous lead grouping (I, aVL,V6; V4–V6; II, III, and aVF)
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:R-wave ≥ 0.04 s in V1–V2 and R/S ≥ 1 with a concordant positive T-wave in the absence of a conduction defect
  
Een pathologische Q golf ontstaat doordat er op de desbetreffende plaats van de ECG afleiding geen electrisch signaal is, doordat het hartweefsel op die plaats is vervangen door littekenweefsel. Hierdoor komt er geen electrisch signaal naar de desbetreffende ECG-plakker toe, maar gaat alle electrische activiteit ervan af.
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'''Notes'''
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*Absence of pathologic Q waves does not exclude a myocardial infarction!
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*Lead III often shows Q waves, which are not pathologic as long as Q waves are absent in leads II and aVF (the contiguous leads)
  
De preciese criteria voor een pathologische Q zijn uitgebreid. Soms is het belangrijk om hier goed naar te kijken, omdat het voor een patient veel kan uitmaken of hij een hartinfarct heeft doorgemaakt of dat er niets aan de hand is.
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For those interested: the [http://www.epi.umn.edu/ecg/mncode.pdf Minnesota Code Classification System for Electrocardiographic Findings] contains a very extensive definition of pathologic Q waves.  
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The Novacode system further classifies ischemic abnormalities in patients with no known history of myocardial infarction:<cite>novacode</cite>
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* High risk of ischemic injury/ Q wave MI:
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** Major Q waves: Q >= 50ms or Q >= 40 ms AND R/Q < 4,
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* Moderate risk of ischemc injury / possible Q wave MI:
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** Q >= 30 ms and ST deviation > 0.20 mV (minor Q waves with STT abnormalities)
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** Q >= 40 ms and ST deviation < 0.20mV (moderate Q waves without STT abnormalities)
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* Marginal risk of ischemic injury / possible Q wave MI:
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** Isolated T wave abnormalities
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** Minor Q waves (shallow Q < 30ms) and ST deviation < 0.15 mV
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* Low risk of ischemic injury
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** No significant Q waves or STT abnormalities
  
Voor de diagnose 'doorgemaakt myocardinfarct' moet aan 1 van de volgende criteria voldaan zijn:
 
<pre>Q >0,04 sec of Q >0,03 sec. mits Q >1/3 R in I II aVF V2V3V4V5of V6;
 
Q >0,04 sec in aVL mits R aldaar >3 mm;
 
Q >0,05 sec in III + Q >1 mm in aVF;
 
QS in V2V3V4V5 of V6mits een R aanwezig is in de afleiding rechts van de QS;
 
QS in V1 t/m V3;
 
QS in V1 en V2 mits geen LVH;
 
QS in II;
 
R-afname tot 2 mm of minder tussen V1-V2 of V2-V3 of V3-V4 </pre>
 
'''NB''' Een Q-golf in afleiding III komt vrij vaak voor. Als er geen Q in II of AVF is te zien, hoeft het  geen teken van een hartinfarct te zijn, maar is het meestal het gevolg van een horizontale hartas..
 
De [http://www.epi.umn.edu/ecg/mncode.pdf Minnesota Code Classification System for Electrocardiographic Findings] bevat een uitgebreide lijst van definities voor een pathologische Q.
 
 
{{clr}}
 
{{clr}}
  
==Referenties==
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==References==
 
<biblio>
 
<biblio>
 
#Alpert pmid=10987628
 
#Alpert pmid=10987628
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#Thygesen pmid=17951284
 +
#novacode pmid=9682893
 
</biblio>
 
</biblio>

Latest revision as of 22:10, 8 January 2012

This is part of: Myocardial Infarction
A pathologic Q wave

Pathologic Q waves are a sign of previous myocardial infarction. They are the result of absence of electrical activity. A myocardial infarction can be thought of as an elecrical 'hole' as scar tissue is electrically dead and therefore results in pathologic Q waves. Pathologic Q waves are not an early sign of myocardial infarction, but generally take several hours to days to develop. Once pathologic Q waves have developed they rarely go away. However, if the myocardial infarction is reperfused early (e.g. as a result of percutaneous coronary intervention) stunned myocardial tissue can recover and pathologic Q waves disappear. In all other situations they usually persist indefinitely.

The precise criteria for pathologic Q waves have been debated. Here we present the latest definition as accepted by the ESC and ACC.[1]

Definition of a pathologic Q wave
Any Q-wave in leads V2–V3 ≥ 0.02 s or QS complex in leads V2 and V3
Q-wave ≥ 0.03 s and > 0.1 mV deep or QS complex in leads I, II, aVL, aVF, or V4–V6 in any two leads of a contiguous lead grouping (I, aVL,V6; V4–V6; II, III, and aVF)
R-wave ≥ 0.04 s in V1–V2 and R/S ≥ 1 with a concordant positive T-wave in the absence of a conduction defect

Notes

  • Absence of pathologic Q waves does not exclude a myocardial infarction!
  • Lead III often shows Q waves, which are not pathologic as long as Q waves are absent in leads II and aVF (the contiguous leads)

For those interested: the Minnesota Code Classification System for Electrocardiographic Findings contains a very extensive definition of pathologic Q waves.

The Novacode system further classifies ischemic abnormalities in patients with no known history of myocardial infarction:[2]

  • High risk of ischemic injury/ Q wave MI:
    • Major Q waves: Q >= 50ms or Q >= 40 ms AND R/Q < 4,
  • Moderate risk of ischemc injury / possible Q wave MI:
    • Q >= 30 ms and ST deviation > 0.20 mV (minor Q waves with STT abnormalities)
    • Q >= 40 ms and ST deviation < 0.20mV (moderate Q waves without STT abnormalities)
  • Marginal risk of ischemic injury / possible Q wave MI:
    • Isolated T wave abnormalities
    • Minor Q waves (shallow Q < 30ms) and ST deviation < 0.15 mV
  • Low risk of ischemic injury
    • No significant Q waves or STT abnormalities


References

  1. Thygesen K, Alpert JS, White HD, Joint ESC/ACCF/AHA/WHF Task Force for the Redefinition of Myocardial Infarction., Jaffe AS, Apple FS, Galvani M, Katus HA, Newby LK, Ravkilde J, Chaitman B, Clemmensen PM, Dellborg M, Hod H, Porela P, Underwood R, Bax JJ, Beller GA, Bonow R, Van der Wall EE, Bassand JP, Wijns W, Ferguson TB, Steg PG, Uretsky BF, Williams DO, Armstrong PW, Antman EM, Fox KA, Hamm CW, Ohman EM, Simoons ML, Poole-Wilson PA, Gurfinkel EP, Lopez-Sendon JL, Pais P, Mendis S, Zhu JR, Wallentin LC, Fernández-Avilés F, Fox KM, Parkhomenko AN, Priori SG, Tendera M, Voipio-Pulkki LM, Vahanian A, Camm AJ, De Caterina R, Dean V, Dickstein K, Filippatos G, Funck-Brentano C, Hellemans I, Kristensen SD, McGregor K, Sechtem U, Silber S, Tendera M, Widimsky P, Zamorano JL, Morais J, Brener S, Harrington R, Morrow D, Lim M, Martinez-Rios MA, Steinhubl S, Levine GN, Gibler WB, Goff D, Tubaro M, Dudek D, and Al-Attar N. Universal definition of myocardial infarction. Circulation. 2007 Nov 27;116(22):2634-53. DOI:10.1161/CIRCULATIONAHA.107.187397 | PubMed ID:17951284 | HubMed [Thygesen]
  2. Rautaharju PM, Park LP, Chaitman BR, Rautaharju F, and Zhang ZM. The Novacode criteria for classification of ECG abnormalities and their clinically significant progression and regression. J Electrocardiol. 1998 Jul;31(3):157-87. PubMed ID:9682893 | HubMed [novacode]
  3. Alpert JS, Thygesen K, Antman E, and Bassand JP. Myocardial infarction redefined--a consensus document of The Joint European Society of Cardiology/American College of Cardiology Committee for the redefinition of myocardial infarction. J Am Coll Cardiol. 2000 Sep;36(3):959-69. DOI:10.1016/s0735-1097(00)00804-4 | PubMed ID:10987628 | HubMed [Alpert]

All Medline abstracts: PubMed | HubMed