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Archive for the ‘carotid interventions’ Category

It is estimated nearly half a  million PCIs are done all over the globe every year .Evaluating diagnostic angiogram is a critical  vital step, but  often times it is given less time and left to fellows .This is done mostly offline by Image  processing software. Curiously , lesion assessment  becomes a causality to the   visual acuity .It ends up  with lot  of whims , intuition and bloated egos of senior cardiologists !

Technical issues

The fundamental flaw in the  lesion assessment is ,there is  a dissociation in choosing the  “best view”  for lesion morphology  and  length  . Size need not be well  assessed in  the same view as morphology . For example , LAD is fore shortened  in LAO caudal view  ,  length measurement would be  erroneous  ,  still morphology may be well delineated .(Vice versa in RAO caudal view )

PTCA guidewire calibratedcalibrated ptca guidewire

Other source of errors

Reference catheter may be far  away in the Aorta , and confer a  magnification error . This becomes important especially in ostial lesions and associated  major branch lesions. The computer uses the edge detection algorithm  which carries an   inherent error .

Advantage of guide wire as a scale

  • Instant online measurement
  • Always on . Repeatedly used in multiple views .
  • You can’t ask for more accuracy .The scale is within the coronary artery  hugging the lesion
  • The end on view is effectively nullified .
  • Magnification  factor do not operate.
  • Finally , and most importantly in complex  tortuous , tandem lesions few mm errors can be disastrous .These calibrated guide wires will make our life lot easier.

Final message

Measuring  a coronary lesion remains a delicate issue . If only we have radio opaque  rings every 1mm or so in the distal end of the guide wire , we can measure the lesion  instantly and most accurately.

This will  definitely make our life  not only simple but help our patients with accurate stent sizing and avoid costly geographical miss (or inappropriately  long stent  that increase  metal load .)

After thought

I do not know whether  any of the existing  guide wires have this facility .(I guess it is not   . . .then , let this idea  be patented in my name !)  After all , It is a mean  task for all those mighty coronary hardware companies to add  few radio opaque rings to all  PTCA guide wires!

Medtronic, Abbot, Boston  are you listening ?

And . . . your opinion please !

 

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Hi all ,

I get frequent comments about my blog. I do try to answer many of them . This is a very unique one , and it is making me think further.Since he has specifically wished his clinical data could be eye opener for others ,  I am jut posting it here . The comment was in response to my article  Who said coronary collateral circulation will not support exercise ?   here is  the extract

Dr. Venkatesan,

I read your blog with great interest and I think I may have something useful to contribute from my own personal experience. I am a 68 year old male with a long history of smoking (for fifty years), and a history of uncorrected hypertension over the years (it has been corrected to normal with medication for many years now). I am a non-smoker now for the past 18 months. I have PAD and a moderate aortic aneurysm of about 3.5CM (ascending and descending) which is being watched with regular vascular scans.
The common femoral arteries in both of my legs are nearly 100% occluded between my thighs and my knees, and yet my ankle and toe blood pressures (and my circulation in my ankles and feet) is almost normal. The reason for that is that according to the vascular scan, my deep femoral arteries are much larger caliber than normal with extensive vascular collateralization by passing the common femoral occlusions.
About twenty years ago before the PAD diagnosis, I realized that I had claudication in both of my calves when I walked a short distance. I expected this was being caused by an arterial blockage in my legs, so I went to the gym every day for about three years, and walked through the pain every day. I believe this contributed to the formation of the collaterals that have perhaps saved my legs and feet.
I also have heart disease, and had a fairly minor heart attack in 1999. No stents were placed nor angioplasty performed at that time. I recently had an arteriogram and cardiac stress MRI which showed that two of the three coronary arteries are now 100% occluded (apparently I had another cardiac event and did not know it). The cardiologist says that the LAD is in extremely good condition and has numerous collaterals branching from it. I have no symptoms whatever from all of this, except that my LVEF is low (about 35%). I walk at a very brisk pace six miles per day, five days per week, and I monitor my pulse rate with a pulse monitor when I walk. I keep my pulse between 115 and 120 which I calculate to be 80% of maximum for my age. I believe this cardio exercise / walking has also helped with the collateral formation, and I am hoping to bring the LVEF back up to a reasonable number with this exercise regimen.
My cardiologist has recommended an ICD, but I have decided against that since I have never had VT or VF or any other type of cardiac arrythmia (except for non-symptomatic PVC’s which I was born with).
I believe that I am the lucky recipient of good genetics to begin with, but also I am highly motivated now to take better care of myself, and know as much as I can about the conditions that I have. I plan to have an echocardiogram in six months to see if the LVEF numbers have improved, and I fully expect that they will have. I give credit to the smoking history for the vascular problems that I have including the cardiac problems. I am a lucky person I think, and suspect that not everyone has the fortunate ability to heal themselves the way I have.
I have asked for copies of my arteriogram and stress MRI records. If you are interested in looking at these I would be happy to share them with you.

The letter ends .

Dear Mr Weigel

Yours is an extremely interesting story  told in a most scientific manner.Thank you .

It gives me great insight  ,  how a  human vascular system  can  transform when confronted with  natural disasters like multiple blocks on its way .A flowing river will definitely reach its destination  however bizarre the path it takes . Human biology is vested with vast reserves of genetic building blocks put on sleep  mode. While billions of dollars are being pumped into do research in human angiogenesis we have tuned a  blind eye to the vast net work of natural collaterals.

Our clinical experiences also tell the same thing . In chronic total occlusion  majority of patients would develop good collaterals if only we do not  tamper  the  main vessel  .None of scientific studied available has proven opening CTOs (Chronic total occlusions) has improved the clinical outcome .

Regarding  the guidelines  for revascualrisation ,  I am yet to come across a standard scientific guidelines that includes the extent of collateral circulation  as one of the determinant for need for revascularisation !

I will definitely use your case study for the benefit of so many patients !  I always feel , a properly interpreted experience  , even from a  single patient   can make a tremendous impact in the growth of science .

Thanks again for sharing your personal health issues !

Dr Venkatesan
Chennai .India .

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Intra cardiac foreign bodies are frequent occurrences  in clinical cardiology practice. The common ones  are intra chamber clots , vegetations  and rarely tumors. Some of these masses are very mobile are  precariously attached to the cardiac strutures  . It becomes a cardiac emergency as a major embolic event  is imminent .

While surgery  remains the  mainstay approach in such situations ,   now it seems possible to trap these mobile  masses with help of catheter and retrieval devices   safely.

The only  issue is , while retrieving  these masses   it  should not be let into the circulation and result in  embolisation  . For this we can develop a   porous net (Fishing net like ) that can be  blown in the distal  chamber or Aorta .

Devices can be structured in way  that a single catheter can be used with different  ports  to capture and  filter  and retrieve  the mass . (  vacuum  enabled suction catheters can be additional option  ) .The whole procedure can  be  accomplished with fluroscoy and fluroscopic guidance . Intra cardiac echocardiography might also contribute .

This innovation will    be  a great  value addition  to the  interventional  cardiology   armamentarium   ,would be   be appreciated by clinical  cardiologists . We in our tertiary  teaching hospital   have  felt  the need for a such a device quiet often  .Currently many patients land up  in  surgical tables  for the sole purpose of removing these clots and vegetations  .Similarly left atrial clots becomes  a contraindication for percutaneous   mitral  commissurotomy(PTMC)   . Such capture devices can be very useful.

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