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Posts Tagged ‘cath lab’

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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No reflow is the terminology used primarily in cath labs where, even  after a successful opening and stenting  of a coronary artery the coronary blood flow is not  restored to myocardium . The point to be emphazised here is blood do cross  successfully the site of  the obstruction but fails to enter the muscle segment  to which the coronary artery is supplying. So the paradoxical situation of artery  being open but the  myocardium is closed to receive  blood flow  happens . This is termed as no -reflow.  Actually it is a  misnomer , and  ideally it should be called “no flow” because  normal distal flow  does not  occur (After PCI)  in the first instance  to get interrupted  later on  and be labeled as  no re-flow.  .The only positive effect of PCI in these situation is blood flow would have improved by few centimeters ie till it reaches  but falls short of myocardium . In fact no reflow , can be termed as  glorified and concealed  terminology  for  PCI failure . It needs urgent action . No reflow is also called as myocardial epicardial dissociation.

Mechanism of no reflow.

Curious case of open coronary artery and closed myocardium !

Coronary  microvascular plugging  is mainly  due to thrombus and atheromatous debri , myocardial  edema , microvascular spasm may also contribute.

Where can it occur ?

  • First described in cath lab, especially following primary angioplasty.
  • It can very  well happen following thrombolysis in STEMI.
  • Can occur in venous grafts.

How do you recognise no reflow?

In cath lab it will be self evident from the check angiogram. Some times it is less obvious and may  require, myocardial  blush score, TIMI frame  count, contrast echocardiography, PET scan etc. In post MI a very simple method to recognise this entity could be the observation of persistent ST elevation in ECG .

Treatment.

Extremely difficult. Almost every coronary vasodilator has been tried.(Nitrates, nicorandil, calcium blockers, etc).Success is less than 30%.  High pressure flushing with saline inside the coronary artery is advocated by some.Others believe it’s dangerous to do it. So prevention is the key. Avoid doing PCI in complex, thrombotic lesions. Use thrombus suction device like export catheter(Medtronic). Distal protective devices are double edged devices , useful only in experienced hands.

Unanswered question

What is the size of the particle (thrombotic and atheromatous  debri)  the   coronary microcirculation safely handle and push it into the coronary venous circulation and the coronary sinus for disposal ?

If we can lyse the thrombus into micro particles by some mechanism and make it traverse the coronary circulation this complication of microvascular  plugging can be treated and prevented .

What is the final message ?

  • No reflow is relatively common condition during emergency PCI done for ACS patients
  • More common in complex thrombotic lesions.
  • Can also  occur in STEMI
  • Treatment is often vexing . In fact the treatment of this condition is so difficult , it can be termed  almost synonymously with “Failed PCI” if flow is not restored.
  • Successful treatment of no- reflow  means not momentry restoration of  myocardial flow  by mechanical and pharmacological modalities ,but to maintain sustained myocardial   perfusion. This we realise, as patients who have had a no reflow during  a PCI, do not perform as well in the follow up  .
  • So prevention is the key.

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The pressure tracing between two chambers of the heart are distinctly different .

 Apart from the magnitude of the  pressure ,(LV at systemic pressure ) The morphology also changes.

  •  RV pressure curve is triangular in shape,
  •  Upstroke is not rapid , (Low dp/dt)
  •  There is no sustained peak ,
  •  There is an early fall and
  •  The pressure falls to zero which  never happens in LV.

Contary to this LV pressure curve is bullet shaped,  with a rapid upstroke, sustained peak, fall later, and does not touch zero.

RV/LV pressure curves in normal persons .Adapted from , Curtiss 1975 Circulation

Note : The shapes of RV curve will change in pathological states.Example in TOF, large VSD there will be left ventricularisation of RV pressure wave forms. Also  in pulmonary hypertension RV pressure may mimic a LV curve.

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                                                          Left main coronary  lesions are  fairly common  during routine coronary angiogram.These may be a critical or a innocuous lesion.The  word “left main” triggers a sort of alarm reaction to many cath lab staff as well as the cardiologists and surgeon.Many times, these left main lesions are detected in patients   with chronic stable angina who have stable symptoms. Left main disese has not been graded  clearly in literature . Often it is perceived , any lesion in LM is serious.

There is an unwritten rule,  rather a medical compulsion  to take a patient  with left main disease  for emergency CABG ( Now some centres ,emergency PCI) .Some institutions make it  a rule these patients  are posted  in the  next available slot in the theatre.

 The basic question we raise here is   “Should we consider all  left main  disease  as  an  emergency”?

Not really , especially when it occurs in a stable angina .One can wait , buy some time to fully evaluate and prepare  the patient  and may be the patient can be posted  as an elective case. It is a well recognised fact that, CABG carries adverse outcome when done as an emergency procedure. This is primarily due to inadequate pre op work up and resultant complications. It is also well known ,  surgical  back up team may not be available in full strength in odd hours .

This post is  to convey the message , that left main is  a serious disease but that doesn’t  mean it should elicit  a panic reaction and be taken as an ultra emergency . There has been many morbid and fatal outcomes in many hospitals due to this apparent  pseudo emergency !

 

Note* 1.Left main  disease during acute coronary syndrome is to be seen in different perspective.2.Some of the proximal LAD lesions are so tight and  could be more significant than left main lesions.

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Interventional cardiology as a speciality is in cross roads.

The number of coronary interventions (PCI) has increased exponentially world over. With increasing  Cath labs and growing  expertise ,  access to PCI has enormously increased  even in underdeveloped countries.  Meanwhile ,  public lack  specific technical information about the appropriateness  of these costly procedures. It is our duty to do self audit on this issue.  .

                           In this context,  the evaluation  following a PCI  should look beyond  lumen oriented  endpoints.  Many  land mark trials on DES report 3 months are 6 months angiographic outcome and better luminal appearance . Many   tend to worry  more about the status of the stent rather than the patient !  This is primarily because the device companies have repeatedly stressed the technical end points rather than clinical end points .

It is a  well recognised fact  that ,stented coronary artery never guarantees against future  coronary events (ACS) either within the stent or away from it .It is an explict fact that , a patient  after getting a coronary stent , especially a drug eluting stent carries a life long risk of acute stent obstruction and possibly SCD .This information is rarely passed on to the patient in  and hence they are not able to take “learned consent”

It is true ,  one gets  a gratifying feeling  when  opening up a obstructed artery , but we also need  to answer this simple question   What is it’s impact on  patient’s  life  ?

COURAGE & OAT trials have put a break on the  prevailing precondtioned behaviour in the labs, namely any obstruction must be relieved if  technically feasible .

One should recall  the Gruentzig’s legacy  . Whaterver,  we do inside  a  patient’s coronary artery must have some useful purpose . We should not use patient’s  coronary artery to show our expertise and skills !

Dr.S.Venkatesan, Madras Medical College, Chennai, India

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Thousands of dissections happen in cath labs  all over the world every day  very rarely it is painful . The answer is not clear. Both have rich vasa nervorum. Aortic dissection  involves media and smooth muscle . Coronary dissection may also be a  equally painful  , probably we are not recognising it ! or we attribute   all  chest pain in ACS  to ischemia .

Deep dissections into the smooth muscle should be painful.  Type c nerve fibers carry pain signals from heart

Answers welcome.

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