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Posts Tagged ‘stent’

Aorto ostial  stenting requires extra caution and special technique. It always  worry us  what if  few mm of  metal might project into Aorta when we stent a RCA or left main ostium.

To  prevent this ,Merit- medical  has innovated a catheter that help us position the stent exactly at the ostial level .It is  done  with a help of an octopus like buttressing arm that support the aortic wall when the stent is deployed .

Watch the video.

 

Reference

Merit-medical 

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Acute coronary syndrome  is primarily a disease of blood vessel , which perfuses  the heart.  It can even be a disorder of blood, often called vulnerable blood which predispose  for intra- coronary thrombus .

Mind you  , heart is an innocent bystander ! to the onslaught of  coronary atherosclerosis !

Hence , we  often use two terminologies .

CAD : Pure vascular (Coronary )  disease without  any structural and functional impairment of heart  ( No Angina, No myocardial damage ) Most of the asymptomatic plaques  , non flow limiting  lesions, incidentally detected by the modern coronary imaging gadgets  fall in this category.

When does  CAD becomes CAHD ?

CAHD : Coronary artery heart disease .Here not only the coronary artery is diseased , but it has it’s mission fulfilled   ie target organ either damaged structurally (STEMI, NSTEMI ) or functionally (EST positive , Chronic stable angina CSA )

Does the heart does any wrong to suffer from Acute coronary  syndrome  ?

No, it is simply not .The fault lies in one or more  of the following   .Generally at-least two these factors are enough to impede blood flow )  . They  combine to produce an ACS.

  • Blood defect
  • Vessel wall defect
  • Slowing of flow (Stasis)

This is called as Virchow’s triad   suggested over 100 years ago . Still valid in the era of per cutaneous  aortic valve implantation.

* The concept of de-linking  disorders of  coronary  vascular disease  from myocardial disease  is vital  in understanding the implications of current modalities of treatment. 

Even though we PCIs target the culprit ie blood vessel , it need to  realised , we  always fall short of real target . . .namely the heart . In coronary interventions  the catheters and wires roam around superficially over the heart  and they never even touch the heart .This is the reason PCIs are struggling to prove it’s  worthiness over medical therapy in many CAHD patients , which can reach deep  into the vessel, heart  and even every individual cells of heart.

Many (or . . . is it most ?)  Interventional  cardiologists have a bad  reputation for ” failing to look  look beyond the lesion” .  It is estimated  a vast  number  of cathlabs  and CABG theaters worldwide  are engaged in futile  attempt to restore coronary artery patency after a target organ damage is done .This is akin to building flyovers  to dead and closed highways .

Salvaging a coronary  artery and reliving a coronary obstruction is an entirely unrelated and futile  exercise to  a patient who has a problem  primarily in  musculature .

The much debated concept of  documenting  myocardial viability  , before revascularisation  died a premature death as the concept  by itself , was not viable commercially . (Viability studies   , tend to tie down the hands of device industry further , some  interventional   cardiologists began to see this concept  as an  interference to their freedom to adventure  )

Of-course , now  we have  other parameters  phenomenon  like  FFR estimation by Doppler , epicardial  -myocardial dissociation, slow  flow , no re-flow are  gaining importance.

Final message

ACS is primarily a disease of blood vessel but it’s impact is huge on heart. We need to look beyond the lesion .Restoring  a blood vessel  patency  to an ailing organ (Heart ) is not synonymous with total  cardiac intervention  and protection . There is lot more to cardiac physiology other than it’s blood flow. Heart muscle is a too complex organ to be controlled by few balloons and wires  which beat around the bush.

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Are the drug eluting stents really better than bare metal stents ?
A million dolor question ? , No . . . a billion dolor question
A study which answered most convincingly with a huge data base  published in LANCET 2007.
  • 38 trials  , Metaanalysis
  • 18 023 patients with
  • 4 year follow-up of up to 4 years.
  • No mortality difference from bare metal stent vs DES
But unfortunately there is  no takers for this  study . The usage of DES continue to  surge ahead  .
The problem facing the medical science in the current era
It takes years  of research to get  into  the truth    and  still   longer time  for  us  to  accept it ! Ironically  falsehoods have immediate patronage and there is no incubation period !

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pci-ptca-ebm-stent

Scientifically ,  the  indication for coronary revascularisation   should be  based on following

  1. Patient’s  symptom ( more specifically angina , dyspnea is less important !)
  2. Prov0kable  ischemia  ( A significantly positive stress test )
  3. Signifcant LV dysfunction with  documented  viable myocardium &  residual ischemia
  4. A revascularisation eligible coronary anatomy * TVD/Left main/Proximal LAD etc ( *Either 1, 2 or 3 should be  present  in addition )
  5. All emergency PCI during STEMI /High risk NSTEMI

Practically ,

A CAD  patient  may fulfill  “Any of the above 5 or  “None of the above 5” ,  but ,  if   a coronary obstruction  was  revealed  by coronary angiogram  and if he  fulfils The 6th criteria , he becomes  eligible for  revascualrisation

6th criteria

If the patient has  enough monetary   resources (by self  ) or by  an  insurance company  to take care of PCI /CABG *

*The sixth  criteria overrides all other criteria in many of the cath labs .Of course , there are few genuine ones still  fighting hard , to keep the commerce out ,  from contaminating cardiology !

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                                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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Answer: Do  coronary angiogram  for all patients  who had suffered from an acute myocardial infarction* ( Forget about all those mulitpage ACC/AHA  guidelines !).

For an  interventional cardiologist ,  it is often  considered a crime to  follow a conservative  approach !

*Caution This one line guideline is not based on scientific fact  but reality based . Ideally one should identify  high risk subsets among the patients who had an AMI .Patients who had complications during the MI get immediate CAG. Others need  a focused LV function asessment ,  pre discharge  sub maximal excercise stress test or perfusion studies .But this concept has been  virtually replaced by pre discharge coronary angiogram for all ,  in many  of the centres in the world.

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