Dr.S.Venkatesan MD

Coronary artery is the life line  of the  heart.The size ,  branches  and the course are  predetermined . Generally  it follows a  pattern ,  but still  it is   believed  every  human has a unique coronary finger print. (When retinal blood  vessels can do this . . .  why not the coronary  ? )

When the left main bifurcates it has to share its resources equally between the two  daughter vessel (Not exactly . . . LAD is  widow maker can’t be a daughter  !)

The logic would say LAD demands more as it has more  territorial commitment.But if LCX fights for  equality  share there is a  potential conflict here.But when LCX  is very aggressive and  demands  much more than it deserves the  issue becomes further complex

See how this LCX  gets bulk of the blood flow from Left main and no doubt this man came with  NSTEMI and  LAD region ischemia while his posterior circulation is comfortably  placed with  excess blood.

Note: The diameter of LCX even exceeds left main in certain segments.

One suggested formula (not validated ) is  diameter of   LCX +  LAD will be   at-least 150% of left main diameter .

1.5 x Left main diameter  =  (LAD + LCX diameter)

This amounts  to  50%  gain in  diameter   as it bifurcates .

Trifurcation  further increases the width conferring a hemodynamic advantage

What is the implication of unequal bifurcation  Left main ?

Hemodynamically there could be diversion  of flow into a larger orifice .But ultimately since  the blood flow is  determined  by the resistance arterioles at myocardial bed there  may not be any  practical significance . In pathological situations there could be a some impact  due to  stealing . Large LCX is more common with  left  dominant circulation  .