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What is the mechanism of deep q waves in volume over-load of left ventricle ?

Posted Feb 05 2012 8:44am

Here is an X -Ray and ECG  of a patient who came with  palpitation ,  which he  said  descriptively

“I  could feel  it   with  my hands over chest “

He also had class 3 dyspnea  and nocturnal chest pain . (Read here :  What is the mechanism of nocturnal angina in AR ? )

Clinically  it was classical  severe aortic regurgitation .

His x – ray and ECG showed

  1. q  represents  LV end diastole  . The  maximum diastolic  stress  point.
  2. q  indicate septal forces . When  LV is dilated  q  also  reflect cavity potential . Both gets  summed up inscribing  a classical deep q
  3. In severe volume overload   LV  is not only  dilated , it’s  mass increases  and is brought near  the chest wall . Since the leas V 5 and V6 are the most proximal to LV  both  R and q  increase correspondingly (Shall we call as  reversed Brody effect ?  )

Other findings of volume overload of LV are

While deep q  is  very valuable in LV diastolic volume over load there are other useful ECG signs.

  • Increased  qrs  amplitude (May be equally important like deep q . Both always go together )
  • Absence of  typical ST/T changes (Systole is stress free !in pure AR/MR) . Still ,  ST/T changes  can occur if   there is associated  LV dysfunction.
  • Left axis deviation.
  • Left atrial enlargement (In case of MR/ Large L-R shunts / or late stages of AR )
  • Rarely  U waves are reported in LV volume overload*

Can we  dignose volume overload without q waves in V 5 , V 6 ?

Most times no, but if there is associated incomplete LBBB q wave disappears.

Which  is rare in pure volume over-load. In fact absence of q in isolated systolic overload of LV is attributed to the presence of incomplete  LBBB by the ECG legend  Shamroth !

Reference

* http://www.ccjm.org/content/78/8/505.full


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