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Posts Tagged ‘lima’

Why do we do LIMA angiogram routinely during coronary angiogram ?

Posted in cardiac surgery, cardiology-Anatomy, tagged , , , , , , , on December 11, 2010| Leave a Comment »

LIMA-Left internal mamary  artery is the most common arterial  graft used in CABG.It is anastomosed with LAD /and or diagonal artery. Routine visualisation of LIMA is advocated by many , but it is required only  in patients with critical CAD.

LIMA angiogram is done

  1. To confirm the presence of LIMA .
  2. To exclude subclavian  stenosis.(If present hand can steal blood from heart !)
  3. To rule out disease of LIMA (Which is unlikely )
  4. Diameter of LIMA should be matched with LAD .LIMA with large lumens can accelerate restenosis in LAD due excess flow induced endothelial reaction
  5. To identify  any early branching of LIMA .This can divert the  blood flow and underperfuse LAD.
  6. Terminal bifurcation  of LIMA can some times be used as a sequential graft to LAD/LCX/OM
  7. Tortuosity and looping of  LIMA is common but generally has no hemodynamic significance.
  8. LIMA may  provide vital  nutritional support to sternum through direct or   intercostal branches .If  LIMA dependent sternal  blood supply is found to be significant ,   sufficient precautions to be taken and anticipate sternal ischemia related complications.This is especially important in diabetic subjects.

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Can hand steal blood from the heart ?

Posted in cardiac surgery, Cardiology - Clinical, tagged , , , , on March 27, 2009| Leave a Comment »

  • CAD is the major cardiovascular disease of our population.
  • CABG is the most common cardiac surgery done world over.
  • LIMA to LAD graft is the most common by pass done.

The purpose is to short circuit some of the blood meant for the hand to the heart.

But ,  is it always a helping hand ?

May not be . . . at times  of crises  the  hand  sucks  blood  from the heart .This is called coronary-subclavia steal phenomenon

Is it not dangerous ?

How to anticipate or prevent this complication in patients who are posted for CABG-LIMA graft ?

Click on the link for the reveiw article from Annlas of  thoracic   surgery

lima

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Why synthetic grafts for CABG is not popular ?

Posted in Uncategorized, tagged , , on March 15, 2009| Leave a Comment »

CABG is the most common cardiac surgery done world wide. Traditionally saphenous vein graft and LIMA are used .Now radial artery is being used often. The life of venous grafts is short, so total arterial graft is preferred.The issue here is lack of good arteries for grafting especially when a second CABG is required  .

So what  are the options ?

  • Cardiac surgeons often use synthetic conduits for many of the congenital heart diseses.
  • But some how this has never been thought as an option for CABG.
  • This may be due to small nature of the vessels, but now there has been some developments on this .
  • In future sunthetic grafts might replace the conventional grafts.

 

Chronoflex, is one such graft under trial  and is engineered to be pulsatile, biostable, torque-resistant and suturable. Once implanted, the graft is able to incorporate the patient’s own cells and tissue, so that the inner surface mimics the normal environment for blood contact. The material is also flexible, so that the graft can pulsatile like a  vein as it carries blood to the heart.

www.cardiotech-inc.com

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What is the hemodynamic impact on the left main blood flow when LIMA is grafted to LAD ?

Posted in cardiac surgery, Cardiology -Interventional -PCI, cardiology -Therapeutics, tagged , , , on March 15, 2009| Leave a Comment »

CABG is tretment of choice for left main and  complex proximal LAD  lesions. So most patients get CABG in these situations.

The hemodynamic effects of LIMA graft on native left coronary artery can be tremendous and some times deterimental.

  • One of the consistent observation has been , the moment LIMA is bypasssed into distal LAD the antegrade flow through left main is reduced .This is still more significant if circumflex is also grafted .
  • For inital few weeks there is competition between LIMA flow and LAD flow and invariably LIMA wins  , and native leftmain or LAD  flow regresses and many times  closes totally.
  • Some studies have observed accelerated left main and LAD atherosclerosis.
  • The native LAD and leftmain could be a source for thrombi and atheromatous debri and these migrate distally and have potential to block the LIMA entry point  into LAD
  • The advantage of having a patent native left main and LAD  is that if the LIMA  graft occludes later on native circulation may assist.

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Some thoughts about left main disease : Why CABG will always prevail over PCI in left main disease ?

Posted in cardiac surgery, Cardiology - Clinical, Cardiology -Interventional -PCI, cardiology -Therapeutics, Uncategorized, tagged , , , , , , , , , , , , , , on March 6, 2009| Leave a Comment »

Why PCI  in   left main CAD is considered  an inferior modality than CABG ?

CABG is superior to PCI for the  simple reason it provides complete revascularisation virtually in all  patients with LMCAD , while PCI is possible only in a fraction of patients with LMCAD.

If  we take 100 patients  with left main  disease may be ten (At best !)   would be  suitable for PCI ! In other words PCI is contraindicated in vast majority of LMCAD  by technical criteria alone , while there can never be a contraindication for CABG in patients with LMCAD.(Except  when , comorbidity precludes surgery )

Why  PCI in  LMCAD difficult ?

It is  dependent on  technicalities

CABG does not tackle a lesion,  it simply avoids it  and by passes it ” No great brains required”

while PCI takes on the plaque frontally ,  in the dangerous  terrain of  left main artery  itself !

so,  much caution,  planing ,  logistics are required . Further ,  if there is a complication there is a potential

for catastrophe  as the only  supply line is cut off . This is the reason , cardiologists were worried to try this on

unprotected left main. (Protected LMCAD refers to left main disease following CABG  wherein atleast   LAD or LCX is  grafted )

Points to ponder in LMCAD

  • PCI is suited for isolated discrete LM disease.In realty  this is seen in less  than 5-8 % CAD.
  • LMCAD is very often associated  with  critical and multivessel distal CAD . So these patients will be candidates for CABG.
  • Left main ostium or LAD ostial  involvement makes PCI a tougher exercise
  • Calcification is more common in LMCAD that  again makes PCI difficult.

The following article in Feb 2009 is a major blow for proponents of  PCI for left main

http://circ.ahajournals.org/cgi/content/extract/119/7/1013

left-main

http://content.onlinejacc.org/cgi/content/abstract/51/5/538?ijkey=84c977d189e84327c3abbd4c1228de17dd99048a&keytype2=tf_ipsecsha

Final message

  • Conquering left main disease is an interventionist’s  ultimate dream.
  • But, before that they have  to tackle the bifurcation lesions .This is of vital importance, because 2/3 rd of left main  patients have  some form of bifurcation lesions. Current techniques , hardware  and outcomes are far below the idealistic solutions in bifurcation lesions.
  • Till that time ,  CABG would  remain the only choice for all , but for  a small fraction of isolated  left main disease where PCI may be possible.

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Why is LIMA graft superior to saphenous venous graft in CABG ?

Posted in cardiac surgery, Infrequently asked questions in cardiology (iFAQs), tagged , , , , , , , , , , , , , , , , , , , , , , , on November 6, 2008| Leave a Comment »

          During CABG arterial grafts are always preferred over venous grafts , for the simple reason the grafted vessel has to carry arterial blood and not the venous blood. Saphenous veins are tuned to carry venous blood at low pressure.The mean coronary arterial pressure is around 40mmhg and this will damage the saphenous venous endothelium more quickly. The reocculsion rate at 10 years for venous grafts  can reach  60%.


                                                    Left internal mammary artery (LIMA) is the most commonly used arterial graft. This is usually anastamosed with LAD. The lumen of LAD &  LIMA are more or less equal and they match well in character also !

The other advantage  of  LIMA graft  is ,   blood    tends to  flow  both during systole and diastole in a smooth fashion.. Since the venous graft which  hangs from the root of aorta , the  ostium  of venous graft lacks the  hemodynamic benefits of   coronary sinus . (We know the coroanry sinus acts like a  reservoir for  the smooth release of  blood flow into coronary arteries.)

Finally ,  the most important feature of LIMA is

  It is a live graft

LIMA’s proximal origin from subclavian is left intact, so LIMA acts as a live vessel with it’s  vasa vasorum intact ,  which means the endothlium derived relaxing factor (EDRF-Nitric oxide) secretion is not interrupted.This makes the LIMA  an excellent graft , self protected against reocclusion.One may call it a drug eluting graft !

 What is the patency rate for LIMA ?

LIMA patency rates at 10 years is nearly 90 %  .But the graft patency depends on many factors , like diabetes, age, gender, surgical technique ,(Now , beating heart CABG is very popular , where the LIMA patency is said to be slightly lower than conventional CABG) Sequential LIMA grafts, free LIMA graft ( Which  loses the advantage of being  a live graft) have relatively lower patency rates.

What are the other arteries used in CABG ?

Other arteries that could be used are radial artery, right internal mammary artery, and gastro epiploic artery.The patency rates of all these arteries far less than LIMA .

cabg-2

A surgeon testing LIMA flow before Anastomosing it to LAD.

Image courtesy Dr.Mannoj Aggny .You tube

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What are the most common indications for coronary arery by pass surgery?

Posted in cardiac surgery, cardiology -Therapeutics, tagged , , , , , , , , , , , , , , , , , , , , on November 5, 2008| Leave a Comment »

                                Coronary artery  by pass graft surgery has become the most common cardiac surgery done world over ever since it was first introduced by Favalaro in 1969.The common indications  are, triple vessel disease and left main disease in any of the following situationsE.

Elective CABG(Non emergent)

1.Chronic stable angina

Either emergent or elective

1.Unstable angina

Emergency CABG*

1.Acute myocardial infarction.-Cardiogenic shock

2.Failed thrombolysis

3.Failed primary PCI

4.Complications during routine PCI(Cath lab crashes !  etc)

5.As an associate procedure after a  mechanical complication during MI (Septal rupture, Acute MR etc)

*In emergency situations even a single vessel disease would require a  CABG

Hybrid CABG

Combining CABG and PCI in the same patient is followed in very few centres .(Example LAD graft and RCA angioplasty)This is done in patients who have co morbid conditions who can not tolerate prolonged surgical times.Further there can be situations  one lesion is very ideal for PCI  while for other grafting is the only solution.

Controversial CABG

1.CABG as a primary revascularisation  in STEMI*

(Rarely done now , almost obsolete , primary PCI has almost replaced it  . . . but it is still  useful if performed within 6 hours of MI )

2.Incidentally detected CAD*  following routine coronary angiogram.

( *CABG for incidentally detected asymptomatic CAD is  increasing in many parts of world )

Inappropriate CABG

         If it’s triple vessel disese it must be CABG -CASS study (1980s)

                       Coronary artery surgery study (CASS) still has considerable influence among the  cardiology  community in the decision making process  for CABG , even though it is many decades old .There has been a phenomenal development in both medical as well as interventional techniques since  CASS . (Thrombolysis, Statins, ACEI, PCI  DES to name a few) .

                     When CASS study was done many decades ago,it was believed triple vessel disese constitute a  homogeneous population and  carry  the same clinical significance . For example a 90% proximal LAD , 50% RCA and 50% OM technically qualify for a CABG and unfortunately , some of them are  subjected to it even in  2008 !  Now we clearly know, it is not the number of diseased vessels  that is important, but it’s location, severity , LV function, presence or absence of diabetes . Finally , the presence of revascularisation eligible myocardium must be documented in all post MI patients . (Technically referred to viable & ischemic myocardium ).              

              Currently , with the  PCI  & medical management has grown so much, CABG should be reserved only for, critical triple vessel disese , with at least one proximally located lesion (Mostly  LAD  or Left main ), especially in diabetic individuals.

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