Posts Tagged ‘first major diagonal’

Proximal LAD lesions require  specific and early Intervention.Hence we need to know what exactly  we mean by proximal LAD disease.Unfortunately , it means different things to different cardiologists .There is no dispute regarding the  origin of  LAD since it begins with bifurcation point  .The problem comes with  this question !

Up to what distance LAD can be termed as proximal ?

  1. Bifurcation  to   “First   diagonal” of  any size
  2. Bifurcation  to   “First Major diagonal”
  3. Bifurcation to     “First septal”  of any size
  4. Bifurcation to    “First  major septal”
  5. Bifurcation  to   “Any major  first branch ” (Either septal or diagonal )

Answer : I think  4 is the correct answer . But many believe  5 can be correct as well !

Why  there is  confusion in the  definition of proximal LAD ?

This is because the first branch of LAD itself is not a  constant one  . It can either be a septal  or  uncommonly  a diagonal.

It should be noted , the septal and  the diagonal  branches  neither respect   seniority  nor follow a  hierarchy .The first diagonal may be diminutive while the   second or third diagonal may be major one  and vice versa .Further  ,  there can be a trade of  in length and caliber of   septal and diagonal branches  .This  phenomenon is also  common between  diagonals  and   OMs  . All these confound the picture .

Cardiologists even though they are  primarily physicians they are  pro-anatomy  like surgeons when it comes to coronary interventions .

                                  In the strict sense ,  we  need to differentiate a  lesion  from being   physiologically proximal  or anatomically proximal  !

Is there a proximal LAD equivalent ?

There are three  situations  this can occur .

  • Some times a lesion  by  definition may not fit in  as proximal  LAD  but physiologically  few major diagonals  will arise after the lesion.
  • Other situation is , LAD lesion may be  mid or distal but  a major first  diagonal may be diseased  , making it  equivalent  to proximal LAD in terms of physiology.
  • A mid LAD  with a large OM lesion which is running in the D1  territory

Final message

It is ironical  millions of cardiology interventions happen  for proximal  LAD lesions  every year without  even  proper understanding of what we mean by  it ! Youngsters are argued to ponder  over this issue whenever  they indulge in  such cases for revascularisation!


Text books differ in their definition about proximal LAD. Currently , the  SYNTAX  scoring system  has defined the coronary segments in a practical way.


Definition from SYNTAX

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