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Technology is a great equalizer.Never in my dreams, I would  have thought as I drive through the dense Nilgiris forest , a satellite  located 36000 Km up in the sky would guide  me through  every turn and bend most accurately.

The curvy roads are coded with  live traffic  flow in Red ,orange & green . That’s “Google map”  for you. (By the way, proud to note Google runs with an Indian CEO who hails from my city Chennai !)

Now , coming to academics , . .Some one thought,  if the traffic in the entire globe can be monitored with few clicks,  How about  adding live traffic data to the otherwise  dumb anatomical coronary angiogram images we get in a non Invasive  CT scan ?  We can even color code the different segments of coronary artery based on the velocity profile and pressure drop. That is CT- FFR . Now technology is  available to get online live FFR as well. (Siemens )

Live coronary traffic blood flow 

Fractional_Flow_Reserve_Coronary_CTA (1)

Heart flow the newest technology in coronary Imaging and  non invasive Quantitative assessment is possible .It provides direct information about how to navigate the coronaries and intervene only the reddish areas  leaving the greens untouched.

Principle

Its called computational fluid dynamics .A super computer calculates live FFR for the entire segment by measuring the drop in  CT density data in Hounsfield units and translates into pressure equivalents and hence non invasive FFR.This modality has been approved by FDA.The heart -flow and Siemens has come out with onsite CT FFR.

Reality check :Have we conquered the coronary physiology ?

Trying to  understand coronary flow with a engineering mind-set is Insulting the complexities of biology. Be reminded , Invasive FFR is assumed as a gold standard, Inspite of the fact that , its blessed with flaws in concept , techniques ,(Hyperemia vs no hyperimia) and lesional variation . Now ,what is the big deal , a non invasive CT -FFR  is compared Impure gold standard  and claiming a breakthrough ?

Of course,logic would suggest,if both FFRs are flawed why not use  a less invasive one that is CT -FFR. It can atleast save time, cost, and potential procedure related issues.May be ideal in ACS situations were catheter FFR can destabilise the patient.Further, it can provide  continuous live information in a hybrid lab , hence post procedure FFR is readily assessed . (Converting Red coronary into Green ones  would become cardiologists new moto!)

Final message

The point of contention for the modern day  cardiologist is ,they have realized (Not all ofcourse !) in a harsh way that , they must use a physiological confirmation of a lesion severity before indulging on fixing it with a metal. Whether CT-FFR will increase the number of angioplasties  or reduce will remain a mystery . Whatever it does , it should do it for appropriate reasons . We know any technology has a shelf life and If MRI can provide the MRI-FFR (Journal of Cardiovascular Magnetic Resonance January 2014, 16:O55)  , CT will be pushed back for obvious reasons (Prohibitive radiation hazard)

Reference

Status of MRI based FFR 

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True patients* present with symptoms , please , don’t ever think all your patients  bring their coronary artery for general servicing !

Ofcourse , we are the service provider to our patients . Though  heart is a mechanical pump it can never be considered equivalent to automobile engine .

For a Heart service station equipped with 24/7 lab,  the benefits may be  more if you treat the angiogram rather than the  patient.

Let us not misunderstand the word service , please show restraint, your patients will thank you forever.

* Silent significant CAD are indeed a problem in minority that requires selective wisdom.However, we can’t be aggressive hunters for CAD in population, as there is huge cost for human hunting !

Reference

Recent article which debates the issue of PCI in CTO
http://circ.ahajournals.org/content/135/15/1382?etoc=#sec-1

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Coronary artery lumen has unique character . Its well-known  LAD diameter is not constant , it tapers in its distal course.(Unlike RCA which is more tubular ) It is estimated LAD looses 15 % of its diameter for every 30mm length.Fortunately LCX has no such long course to make tapering a visible threat. (Though it may still be an Issue !)

Is there a hemodyanmic purpose for this tapering in LAD ?

Should be, God never designs anatomy without a physiological purpose.We have to find it  out.(Can it be meant for  flow acceleration as the flow is entriely diastolic in LAD while in RCA its both in systole and diastole ?_

What is the relationship between tapering angle and final distal diameter?

Schematic of an artery with a tapered angle of 0:16 .Ref XIANG SHEN Journal of Mechanics in Medicine and Biology Vol. 16, No. 8 (2016)

So, if you have a long lesion in proximal LAD and planning to stent with a 40 mm or long  stent the distal end is hyperinflated by atleast 1.5mm, if we use a non tapered stent. Though , gain of extra  diameter  in distal segments might appear attractive, this may not work to our advantage , since it defies and distorts  the natural hemodynamic flow pattern. Further , when you have tapering vessel, proximal optimisation becomes more important.

How about a tapering coronary stent ?

It should be a welcome addition to our already overflowing coronary hardware in fixing long lesions . Its still a surprise why only very few are making this type of stent.

Meril has developed a  tapered stent up to 60 mm long  (Biomime morph).It should be useful in specific lesions sub types.Its worthwhile to note  tapering stents are used more often in carotid artery .

Advantages of long tapering stent over two stents of different sizes.

  • It avoid the vulnerable overlapping zone with double metallic load.
  • Possibly cause less restenosis
  • Low risk for stent fracture
  • It reduces procedure time and of course the cost of stent by 50 %

Why the concept of Tapered stent is not that popular ?

I can only guess, probably lack of free availability and  to a certian extent ignorance as well !  However ,current status about tapering stents is expected to evolve, though many cardiologist still  feel it’s not clinicaly important issue to use a tubular stent in tapering vessel.

Alternative  interventions in tapered vessel.

  • Wall stent and other self expendable stents
  • Tapered balloon Angioplasty (Laird Am Journal of card 1996)

Experts  in this modality are  welcome to share their experience.

Reference 

1.Zubaid MC, Buller C, Mancini GB. “Normal angiographic tapering of the coronary arteries”. Can J Cardiol 2002; 18: 973-980

2.Timmins LH, Meyer CA, Moreno MR, Moore JE Jr. “Mechanical modeling of stents deployed in tapered arteries”. Ann Biomed Eng 2008; 36: 2042-2050

3.Javier SP, Mintz GS, Popma JJ, Pichard AD, Kent KM, Satler LF, Leon MB. “Intravascular ultrasound assessment of the magnitude and mechanism of coronary artery and lumen tapering”. Am J Cardiol 1995; 75: 177-180

4.Laird JR, Popma JJ, Knopf WD, Yakubov S, Satler L, White H, Bergelson B, Hennecken J, Lewis S, Parks JM, Holmes DR. “Angiographic and procedural outcome after coronary angioplasty in high-risk subsets using a decremental diameter (tapered) balloon catheter. Tapered Balloon Registry Investigators”. Am J Cardiol 1996; 77: 561-568

5. YONG-QUAN DENG, ZHONG-MIN XIE and SONG  ASSESSMENT OF CORONARY STENT DEPLOYMENT IN TAPERED ARTERIES: IMPACT OF ARTERIAL TAPERING XIANG SHEN*, Journal of Mechanics in Medicine and Biology Vol. 16, No. 8 (2016) 1640015 

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Medical practitioners often need to refer a patient from small clinics and hospital to a higher center  for providing state of the art care provided by specialty hospitals armed with ultra  modern Imaging , gadgets and devices.

Recently, I happened to see an elderly women with ca breast, radiculopathy, dilated cardiomyopathy, triple vessel disease , stented  /by passed  with 3  CABG grafts later, followed by an  ICD and CRT, .Her CRT became non responsive after a failed attempted AF ablation.

.evidence-based-medicine

After a prolonged stay in the posh AC suit of a renowned corporate hospital the patient was feeling exhausted and weak with multiple tests and procedure.The patient found things annoying as every consultant and support staff behaved like a programmed robots with artificial smiles and compassion.

She and her family  was tolerating things, but desperately required a break from 24/7 attention (which was without much progress either ) . After a mini family confabulation, they decided to request the treating consultant to refer her to a lower center for a more humane care.

From here on its  fiction . . .

The doctor agreed (after Initial amusement ) and asked his secretory  to write  a letter which sounded something  like this,

Please get permission from the hospital desk for referring this 70 year old gentlewoman to a “lower health care center” as she feels exhausted with our treatment and decided to opt for a more simplistic, supportive , compassionate  and humane care that’s is devoid of claustrophobic gadgets and  machines .

We also acknowledge we are neither equipped , nor has personnel  and expertise to provide that sort of human care,  you demand ,! We have to respect science more than individual patient needs . We are taught, paid and live for science first ! so please forgive us.

But, we respect your concern and will transfer you to a primary health center.Thank you for being with us this long , and helping us the master some cutting edge skills and helped science to grow.

picture2

By and large, the concept of tertiary health care can very well be a myth.(With few exceptions)  It means  mechanised  care that primarily involving aggressive organ specialists who want  attack the  disease without mercy for the patient.

The uttering  here  might sound provocative , especially  for the families who have benefited from cutting edge medical technology , . . .

Still ,  the rate of growth of irrational organ or system based  tertiary care is growing in dangerous proportions , and very soon we will realise the disastrous consequences of this pathological mindset of modern medical intellect.

What we need , ?  Emergency bulk supply of  “right and straight” thinking “whole body specialists‘ . Who are they ? they include the  Internal medicine graduates ,humble general practitioners ,family physicians and geriatricians .These genre are currently in the sidelines suffering from artificial low self-esteem (atleast In India !) Soon I expect they should emerge stronger and take control of the sagging medical profession from the clutches of pseudo scientific specialty hospitals who keep the cost of medical care Insaningly high that  drains the  global GDP in a meaningless manner.

Will WHO act ? Should they be conferred the veto power and tightly control when to refer a patient  from a lower to higher center and vice versa !

For those of you who don’t know who is who  ?

WHO stands for World Health Organisation , a united Nation organisation which is the apex medical body & guardian of human health .One of their Job functions is ,they are expected to act when there is Inappropriate health delivery and expenditure .( Unfortunately even most of the medical professionals think WHO exists for only one reason  to eradicate mosquitoes and vaccinate children ).

WHO need not think they exist only to guard health of poor under privileged , they have a critical responsibility to prevent wrong therapies committed to rich and affluent as well ! and more so  these unnecessary modalities  spill over from rich to poor in the name of  equality !

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Knowledge can be a dangerous asset sometimes . A modern day cardiologist reassured a patient  who had an unusual dyspnea after a muti-vessel stenting for a not so complex lesions following an anterior MI.The doctor  was not mystified when the patient uttered this complaint. In fact he was so cool , reassured the patient since he was taking  Ticagrelor ,and it’s well recognised to cause dyspnea in some patients.

Few days later patient  called  again and informed that the  dyspnea is getting more intense  and ultimately he was rushed to hospital only to diagnose  subacute stent occlusion and a fresh ACS.

What do you learn from this story ?

Caution , extreme caution is required when dealing with symptoms following PCI and especially dyspnea.

A brief review about  Ticagrelor dyspnea conundrum

  • Ticagrelor  ,a reversible P2Y12 blocker  has a peculiar side effect of dyspnea (Which happens to be a cardinal symptom of heart disease as well )
  • Its reported by up to 30 % of patients who receive it.
  • It can be either exertional  or even at rest.
  • It seems to be dose dependent
  • Onset within 24 hrs , upto 1 week.
  • Pulmonary function not affected.
  • Cardiac function thought to be unaffected.(No correlation with LVEDP though)

Mechanism of dyspnea with Ticagrelor (Presumed)

  • Its direct cortical effect due  sensory neurone  P2Y12 blockadae.
  • Due to Adenosine

Remedy 

  • Reassurance(Possible in few , but risky unless absolutely confident)
  • Encourage Tea intake (Theophylline might nullify if its Adenoisine induced .
  • Discontinuation is  the specific option (up to 10%)

Final message.

Dyspnea is a  unique side effect of Ticagrelor. Unexplained dyspnea is a delicately dangerous symptom in a post MI patient as it may directly imply a silent ischemia induced LV contractile dysfunction and acute raise in LVEDP.

Don’t ever take it easy and attribute all episodes of  dyspnea to Tiacagrelor .If you are really not convinced consider switching the patient to a different anti-platelet drug. Its simply not worth for both patient and physician to spend anxious moments.

Reference 

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We know,  classical Atrial flutter (Also referred to as typical /Common AF) records  saw toothed F waves  due to continuous atrial electrical activity across a macro- reentrant circuit within right atrium.

Though this  saw tooth pattern is easily recognised , it’s often difficult to say  whether the saw is facing upwards or downwards ?

ie  Is the flutter waves are inverted or upright ?

The general rule is the shallow stroke (one with a lesser slope) is to be termed  as antegrade  / initial deflection that will determine the direction of flutter waves.

mechanism-of-inverted-flutter-waves-in-atrial-flutter-saw-tooth

This is because , the forward limb traverses the slow path  of the circuit namely the cavo-tricuspid Isthmus, it then ascends up in the inter atrial septum (There by inscribing inverted F  waves  in leads  2,3,aVF .The return circuit  is relatively fast,  crossing the antero -lateral   free wall  right atrium and hence the later half saw tooth has a  sharp deflection )

In Reverse typical flutter  the flutter waves are upright (with a shallow slope ) in inferior leads but still uses the cavo- tricuspid Isthmus

* Note: In lead the polarity of F waves in V1 it will be opposite of that of inferior leads.

mechanism-of-flutter-wave-upright-or-inverted

Why should we bother about direction of flutter waves  ?

It may not be important for those hifi EP guys who can ablate complex arrhythmia with intra cardiac GPS catheters and accurate electro anatomic mapping system. Still , the  surface ECG always help us understand the basic circuits of flutter.

Reference

atrail-flutter-review-best

Reverse typical flutter should not be confused with atypical flutter where typical saw tooth waves are uncommon.The later group is termed as atypical atrial flutter that arises from various other focus including left atrium.

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If you think , the  various appropriate use guidelines for cardiology practice are collection of great scientiifc truths , beware . . .many  of them hide behind semantics.  (After all , English is an unique language one can play  with it !)

Is it not funny , to note a  recommendation  that goes with a caption “may be appropriate” conveys exactly the same meaning as “may not be appropriate” as well .

Here is a rare article which tries to expose the importance of  linguistic Interventions in cath lab that can Impact the patient outcome for good or bad.

http://www.invasivecardiology.com/articles/%E2%80%9Cmay-be-appropriate%E2%80%9D-pci-ambiguities-appropriate-use-classification?inter_email=alNyWXNEY3VFR3RzZEM2b3hHRjVseDIzWjlCdkN1Snp2MDlNbnR5RkVacz0%3D

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