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Archive for February, 2017

It has become fashionable for many current generation cardiologists to stent the LAD   with proximal end  liberally extending into left main shaft  in Medina 0, 1, 0 or (1,1,1 )lesions involving distal left main often  jailing the LCX . This concept came into vogue as it helped bail  out few  hemo-dynamically  unstable patients with true left main bifurcation lesions during primary PCI .Of course , it’s potentially useful strategy in  emergency , if  extended into routine situations (like all stable proximal LAD/Bifurcation ) we are bound to create few problems.

the-only-thing-more-dangerous-than-ignorance-is-arrogance-quote-1

Rapidly protecting the left main with a long single stent down into LAD is an easy way out for tackling distal left main /LAD combined lesions.  Conceptually it asks you to forget the LCX outright.(Coronary outrage for some to call LCX as  a side branch of left main ! ).Of course, one can reconstruct the LCX  ostium by other means or a second stent if required.

Final message

Conquering  left main disease  with a long stent right from its origin or mid shaft to  LAD (Some times  from Aortic ostium ! ) may be an  interventional pride for the cardiologist. But , in no way it  imply we have crossed the  final frontier in LM disease.In fact,  putting a left main coil is the  easiest task among all  PCI since there is little expertise required to cross the lesion .Maintaining its patency   medium  long run and thus beating the CABG  is  true achievement  ! Achieving  an acute patency  of left main and wheeling out the patient live from cath lab can not  be reason for permanent rejoice ! One should realise his life is at the mercy of DAPT and its pharmakinetics which we know can be unpredictable !

“Protecting the patient is more important than a protecting left main” 

Just because a technique is easy to accomplish it doesn’t confer the right to misuse it .The argument “my patient” is doing fine with this type of stenting  is not an appropriate way of justification.

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PCI and coronary stents are revolutionary concepts  but they may not be  great life saving devices  . . . though the collective cardiology wisdom may seem to suggest so !

stents-india

The ideal way to describe a stent could be “Its a metal coil , if inserted properly in certain population of severely obstructive forms coronary artery disease may save some lives in acute situations  or give relief to pain in non acute situations”

*While the true benefits for the patient population is unsure . . . it’s absolutely certain stents  confer highest  quality of life to the  manufacturers and their chain of associates including the Noble professionals !

sir-william-osler

I wonder , what would be his comment about ubiquitous stents that rule the current era !

Learnt cardiologist’s  will know the true life saving potential of these stents (In the way its been currently used ) Their conscience will also tell how Inappropriate and Indiscriminate usage of stents has possibly consumed more human lives that may even beat the number of lives saved .(Oh, Its wild, rude statement  friend!)

I sincerely believe the move by Government of India to control the stent price ( to enable all our countrymen to get it)  . . . as if  “stents are the only staple diet” for heart patients is ill-founded and dangerous .

What the Government may not be aware of  is  . . .This 45000 crore omnipresent stent  industry is playing havoc in the life of patients not only financially  but also biologically to harm their blood vessels.

It is near foolish to tackle the scourge of human beings -Atherosclerosis,   a diffuse medical disease with a lesion specific intervention .This is especially true when we want to tackle it in population based approach . Yes, some super rich and elite  get sophisticated stents thinking that they are privileged .Please understand  rich tend to suffer more  with technology. Often times non affordability is also a bliss for the poor .(Rubbish ,won’t agree  . . . Is it , will realise later !)

Who will tell this to our  policy makers ?

Never ape the private sector health care , states must have different priorities.There are Infinite number of studies that  very clearly reveal medical management and life style modification is the sure and successful way to tackle CAD.(I think I need not dwell into this as evidence is explicit .)

Meanwhile, let me give one example of  the futility of innovation and perils of premature release of half baked science .While one section of Industry is coming out with stents made up of exotic new metals , simultaneously other group is innovating and experimenting the exactly opposite , how to get rid of the metal ie bioreabsorable stents. Mind you, one of the latest generation stents was severely reprimanded in a Landmark trial ABSORB 2. Its a comical irony some of the hospitals and cardiologists  feel bad  to miss this red flagged stent that are taken out of their cath lab because of price cap. ( A pat for the Govt for this !)

Its a multi billion dollar Industry (Note : there is no pardon for Indian companies to exploit either !) trying to disseminate a commercially motivated concept intelligently including the stake holder Government in their loop. The move to liberalise stent usage is  most unfortunate thing  as the Govt has  inadvertently increased the risk of abuse .Let the new age Indian not be proud  about “Stent for all ” movement since the  Govt will ultimately  have to shell  out for this imperfect therapeutics through public insurance .

Final message 

Though capping the price of the stent by Government  do carry  some sense  . . . ultimately      I feel its a trap . It’s akin to let loose a dubious  modality in public domain within easy reach . Already the companies want to increase per capita metal consumption. That process will only get accelerated now.

The Government must realise there is an urgent &  broader issue to be addressed by health ministry.Its not only in cardiology but in all walks of health delivery system. How to prevent “contamination of  medical science by pseudo scientific intervention fueled by corporate greed ? They should start  sensitizing the young medical professionals in medical schools that will help the Noble profession remain Noble !

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Now , some one wanted to know,  Can we diagnose unstable angina without Chest pain ?

Crazy question isn’t , Angina by definition  should have chest pain .There is nothing called silent angina , only silent Ischemia  .

  • We know Ischemia can occur silently .
  • We also know STEMI can occur silently (About 10 % of MI do occur without any symptoms )
  • If STEMI occurs  silently  why not UA/ NSTEMI combo ? (Collectively called as  NSTE-ACS)

The debate goes like this .If stable angina can present with equivalents ? what prevents  “Unstable angina”  to present with  Anginal  equivalents without chest pain ?

If  a diabetic patient who had a silent MI in the past  . . .  subsequently  experience  severe episodes of resting ischemia  , will he feel the pain , that is supposed to occur  with his  “unstable angina”  or not ?

Hmm , difficult to guess right,   So it seems highly plausible  UA/NSTEMI  do  occur silently ! Literature hasn’t looked into this specifically. Chest pain is built integral  into definition of UA , infact it is a symptom  complex rather than an disease entity by itself, while NSTEMI is ECG and enzyme combo ! Making the term  NSTE-ACS  look  perfect.

Any other technical explanation ?

The concept of Ischemic cascade says angina occurs last, well after biochemistry , wall motion defect and ECG , hence its distinctly possible for UA/NSTEMI present to be painless !

Final message

Anginal pain perception is related to intactness of neurogenic circuits and also probably the severity of Ischemia.If full thickness myocardial necrosis can be painless in few, nothing prevents from an episode of UA/NSTEMI  be truely painless .

Clinical implication of this conundrum

Can we admit a patient as UA/NSTEMI with out chest pain ?

Yes, it would seem so .

No, we can’t .

Indeed we can , if ECG changes are there .

No, we can admit even with normal ECG if its real unstable angina.

This is the crux of the problem in ERs all over the globe. Our knowledge base is simply not good enough. Every one of us has seen Troponin positive silent NSTEMIs ! but . . . to me still something is missing in the link .

Modern day approach 

Pain or no pain,any  fresh ECG changes ( Both T and ST shifts*) should be rushed to cath lab.Whenever you are not sure .Always better to err on the side of over investigation.That’s the mantra ! So ,you do an Angiogram , find an Incidental intermediatroy lesion which may not be responsible for the ECG changes but you are compelled to go after it FFR//iFR , OCT, IVUS and so on !

*There is huge list of non Ischemic ST/T shifts in ECG that can be read elsewhere .

Counterpoint

Can’t agree with this article. Foolish to diagnose UA without chest pain. Never  treat ECG  in isolation unless its a convincing  ST elevation or depression with clinical input and thorough scrutiny of  past record . Realise , how important is  the basics principles of medicine taught  by Oslers and Cushings a  century ago.

 

 

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Artificial pacemaker is one of the major discoveries in cardiology that has given new lease of life to patients suffering from serious bradycardia and heart blocks . Now, the technology has grown beyond pacing , for delivering shock ,defibrillate , resynchronise failing heart etc. For accomplishing  all these tasks we need electrical power . . . non stop on board !

Though , the energy required for sustaining an electric pacemaker is miniscule (About 40 micro watts) still, the lithium ion battery can last only around  10 years with the available technology.Various alternate sources for power* are being  explored. One great innovation is on the horizon .A new “scientific spark”  came from a totally unexpected  quarter.

 If Automatic Swiss watch can run without a battery  life long ?  Why not a cardiac  pacemaker  ?

 How about harvesting mechanical energy from the heart itself  ? (The ultimate biological bundle of energy ! ) .

The concept was  originally suggested by University of Berne Switzerland , researchers from Stanford has successfully used the cardiac  muscle activity as a dynamo to generate and store minute amount of electricity that can sustain heartbeats in an electro  mechanical coil loop model.

heart-powered-pacemaker

A person’s heartbeat  moves a magnet and generate electricity for a pacemaker

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Trials done on pig’s heart are promising .(Reference 1)

Final message 

The idea may look dramatic , but it works.Hope  it becomes reality in our patients in near future.

Further reading

* Creating gene modified  biological pacemaker cell is .

Sharing this  article from  Via: New Scientist

By Lisa Zyga
Science Blogger
InventorSpot.com

  At first glance, this idea seems somewhat impossible, like using the movement of an engine’s pistons to power a car. However, researchers David Tran and his colleagues from Stanford University explain in a recent patent that the idea is very plausible. For one thing, a heart-powered pacemaker can generate and store more electricity than required to operate, and use the stored energy when needed. Also, a battery could be included in the pacemaker, and power from the heart would extend the life of the battery.

Overall, the researchers hope that the invention could at least double the lifetime of today’s pacemakers. Currently, the batteries in pacemakers can last up to ten years, although they typically last only four to five years. (Originally, batteries lasted for as little as a year.)

The invention also has the potential to reduce the size of the pacemaker by one-half or more. For example, a typical commercial pacemaker with a volume of 16 milliliters may be reduced in overall size to as small as 1-8 milliliters.

An embedded generator could continuously produce power in several ways, such as through electromagnetic induction or the piezoelectric effect (electric energy generated via mechanical stress).

In the Stanford team’s design, the generator is implanted near the heart wall, such as attached to the myocardium or pericardium, which would subject the generator to regular pulsating movements produced by the beating heart.

The generator itself consists of a magnet, a conductor (both micro- or even nano-sized), and electrical leads hooked up to the medical device. Contraction of the heart muscle causes relative motion between the magnet and the conductor (such as a coil of wire). This relative motion between the magnetic and coil induces an electric current in the wire, which is transmitted through the leads to the implanted pacemaker.

Movements produced by the beating heart would have a frequency of between about 0.5 Hz and 2 Hz, which could generate between 40 microwatts and 200 microwatts of power. The pacemaker would only require about 40 microwatts, so the excess power could be stored and used for later use, such as when the heart stops beating.

Besides using the movement generated by the muscular contractions of the heart, other versions of the pacemaker could generate power from heat differentials, physiological pressures, and flows and movements, such as blood flow. And in addition to pacemakers, the researchers suggest that similar systems could be used to power defibrillators, ventricular assist devices, muscle , neurological stimulators, cochlear implants, monitoring devices, and drug pumps.

Reference

http://powerelectronics.com/energy-harvesting/energy-harvesting-poised-eliminate-pacemaker-battery

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