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Posts Tagged ‘left main coronary artery’

Can we shoot the Left main at the bed side !

Posted in cardaic physiology, Cardiology -Interventional -PCI, Cardiology-Coronary artery disese, echocardiography, tagged , , on March 2, 2012| 3 Comments »

Left main coronary artery is  considered as the sanctum sanatorium  for  the cardiologists .

One would wish  to rule out  disease of left main  in any given  patient with CAD.

Though there are strong clinical predictors of  LMD, this  segment of the coronary artery  tends to  throw   surprises.

A  strongly positive stress test,  ST elevation in AVR  , fall in blood pressure with exertion  are good markers of left main disease.

Still,  in the era of  optical coherence tomography (OCT )  and IVUS  , we do  have a simple tool that can image the left main coronary artery fairly accurately .

We know the  resolution power of  routine trans thoracic echo  is 3mm and above  . (It can detect vegetation of that size easily !)

So , it can easily accomplish  the task of  imaging the  left main ostium .(which is a minimum of  4-5mm diameter )

How to image left main by echo ?

  • Parasteranal long axis  or short axis  the ideal view. Short axis would also  help.
  • Normal left main is easily diagnosed  by two parallel  lines . ( See above picture )
  • Plaques are  diagnosed when this line is  distorted  and filled by haziness.
  • Significant ostio proximal  lesion must never be missed by TTE .However distal left main can not be assessed in most .
  • Doppler assessment may not be possible in all as pulse doppler sample volume can not be placed in left main.
  • Trans esophageal echo would increase the yield.

Final message

Processing power of echo machines  and  their image quality has improved  vastly over the years. The existing literature about left main imaging  by echo are based on old generation machines. The data are as obsolete as those  machines . This has to be kept in mind.

I wonder why most cardiologist are averse ( rather feel guilty ) to report  the  status of  left  main  artery  by  echo cardiography .

Every patient with  a  positive TMT must undergo a  focused echocardiogram  of  left main . You will be rewarded with a  good glimpse of the sacred segment  of coronary artery 9 out of 10 times  !

So , can we shoot the Left main  at the bed side  ?

Yes definitely  . . . if only we wish to !

* A correction

The left coronary visualised in this parasternal Long axis view is in fact exceptional. The ostium and shaft often better seen in short axis in around 3-4 O clock position.

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God blesses a few , with a trifurcation of their left main coronary artery !

Posted in Cardiology - Clinical, Cardiology -Interventional -PCI, cardiology-Anatomy, Uncategorized, tagged , , on January 28, 2011| Leave a Comment »

God creates life  with  infinite variation .  The  heart gets  bulk of its blood supply from the left coronary  artery , which divides into two  after a short course.  Bifurcation is the rule . Left main becomes  left circumflex and LAD  in about in 85-90 %.

Note the left main divides into 3 equal caliber vessels.very lucky to have such a branching pattern !Distal left main is unloaded by three large ostia . This makes stasis of blood in left main very unlikely . LAO caudal view

 

 

Note : The OMs are small in these people. RAO caudal view

Few men and women are blessed with three branches from LCA . The anatomical and physiological importance of this  branching pattern  is not well analysed in the literature .There  could be  few advantages  of having a trifurcation instead of  bifurcation .

  • Left main  impedence is less in trifurcation . This is due to the fact ,  left main empties into three distinct ostia rather than two.The combined  cross sectional area of these three ostia  confers a hydrodyamic advantage.
  • The importance of  any proximal LAD lesion in these patients , is negated  by  33 % as two other vessels are there to take care the  rest of the heart.
  • A large Ramus usually  supplies a vast area in the angle between LAD and LCX.  This   has a potential  to protect against ventricular  fibrillation during acute occlusion of LAD  by providing  electrical stability .

Disadvantage of trifurcation !

  • It is also a fact , people with a large Ramus may have a trade off by having a diminutive diagonal or OM .
  • A trifurcation with a small calibered  ramus  can often  be a disadvantage , as it is prone for atherosclerosis  since it  restricts  left main flow  by  venturi effect . (The first rule of atherosclerosis states its  prone at branching points)

* A related blog  elsewhere in my site . The explanations  offered above are based on personal observation .

https://drsvenkatesan.wordpress.com/2008/12/16/what-is-clinical-significance-of-ramus-intermedius-coronary-artery/

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