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Archive for the ‘Infrequently asked questions in cardiology (iFAQs)’ Category

The gradient across coarctation  is not  simply (& solely ) determined by degree of obstruction , as one would believe.Understanding the hemodynamics and various factors that can influence the gradient is essential Relieving the  obstruction /gradient by stent or surgery  may not be synonymous with successful treatment as we understand now the entire aorta right from the root to abdomen can influence the gradient ,along with systemic factors.We also know , some of these patients harbor histological abnormalities in the entire stretch of  Aorta , what is  being  referred to as pan aortopathy  , that may influence the long-term outcome.

coarctation gradient collaterals002

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Originally used in early 1990s,  self expanding coronary stents (Wall stent from Boston scientific )  subsequently lost interest because of delivery related issues. Many feel , it makes cardiologist judgment tentative and delivery system prevail over our hand skills. It is possible stents can longitudinally jump with high radial force making a geographical miss more likely.While it could be true with any technique till we master it, one should recall ,most endo-vascular work other than coronary still involve self expandable techniques.

Balloon expandable  stent is ruling the PCI field  for more than 2 decades. There has been recent surge of interest in the self expanding  technique and it could make a great difference in the PCI arena provided we take the proper cues.

Self expanding stents have some unique advantage

  • It has  high radial force.
  • Approximation with lesion is best
  • It tends to take the shape of the vessel than any other stent
  • Since the mal-opposition and gap between stent and vessel wall is minimal stent thrombosis is theoretically is  lower.

Where is self expanding stent useful ?

  • Ectatic and very irregular lesions
  • Bifurcation lesions where multi dimensional vessels with different shaped ostia converge.
  • Eccentric lesions (Non calcified) may be benefited by self expanding stents
  • Self expanding covered self (Is it available >)  may be the best bet for perforations and for thrombus  to be plastied against the wall.
  • In some small vessels PCI
  • Finally it may have a  role in primary PCI (APPOSITION 1 to 5 )

What are the self expanding stents available ?

  1.  Devax system   ( 2003)
  2.  Stentys
  3.  Radius (Boston scientific)
  4. Capella Sideguard.
  5. Cardiomind Sparrow
  6. vProtect luminal shield.

Final message

For some reason , self expanding stents were not tested widely  and  large scale data is not available. However ,  they are unique modalities in metal delivery and must be mastered and many patient subsets will be benefited by it. They are not obsolete yet, APPOSITION 5 study will answer some of the issues.

Reference

1. Agostoni P, Verheye S. Novel self-expanding stent system for enhanced provisional bifurcation stenting: examination by StentBoost and intravascular ultrasound. Catheter Cardiovasc Interv 2009;73:481
2.Jsselmuiden A, Verheye S. First report on the use of a novel self-expandable stent for treatment of ST elevation myocardial infarction. Catheter Cardiovasc Interv 2009;74:850
3.Verheye S1, Grube E, Ramcharitar S, Schofer JJ,.First-in-man (FIM) study of the Stentys bifurcation stent–30 days results.

EuroIntervention. 2009 Mar;4(5):566-71
4. van Geuns  R.-J., Tamburino  C., Fajadet  J.,  Self-expanding versus balloon-expandable stents in acute myocardial infarction: results from the APPOSITION II study: Self-expanding stents in ST-segment elevatation myocardial infarctiion. J Am Coll Cardiol Intv. 2012;5:1209-1219.

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Every one talks about  coronary excesses ! It happens  both  in acute and chronic  fashion , not withstanding the inappropriately  understood  . . .   appropriately  released  guidelines  on inappropriateness ! The  burden  of coronary syndromes of the humanity, I am afraid would  include these man made excess as well !

I stumbled upon two  small  “gems ” in this other wise wild dark  cardiology literature  .One from Kamaer , Netherlands and other from  Escaned from Spain.

Both  talk about a  simple and logical modality in the management of STEMI . If bulk of the STEMI events are due to coronary thrombosis just tackle it  . No more  . . . no less” Stent only , if there is tight residual lesion.

1. From Amsterdam , Holland.

krammer thrombus aspiration alone priamry poba for stemi no stent

2.This one is from Spain.These studies I am sure , only a fraction of the interventional community would have read .Reason ? We are always hijacked by the moments of glamor ! I am just sharing them .hope few are benefited

primary POBA thrombus aspiration alone for stemi no stent stemithrombus aspiration alone for stemi no stent priamry pobaThese two studies with total number of 44 patients has a potential to redefine  the entire practice pattern of acute interventional coronary care.(Of course , if only , we are ready to make sense out of it !)

But , the concept will be heavily banished by strong visible and invisible forces   for the simple reason it suggests a true possibility  of knocking  out the role of  stent from acute STEMI arena.

When I discussed with my colleagues  for a large scale study  on isolated thrombus aspiration in STEMI , they told it  is not possible for ethical reasons !

I was amused , denying such a study is biggest ethical blow to the field interventional  cardiology !

Final message

Proof of concept does not require numbers .A study with less than 50 subjects  can be far superior than multi-centre ,multi-blinded , self steered ,peer reviewed largesse ! The truth of the study lies in the core consciousness  of people who do it , not in the numbers and exotic statistical methods !.

After all , one of the greatest medical study  was  done by James Lind  (Father of RCT) who discovered vitamin c as an antidote for scurvy,  with a hand full of sailors  while they crossed the Atlantic many centuries ago !

After thought

You say , thrombus aspiration is great , Why the hell , TAPAS , INFUSE AMI, and TASTE studies  confuse us regarding thrombus aspiration  ?

Don’t blame it on thrombus aspiration .We do it perfectly . It is because of what  we do after that ! We decorate the coronary lumen finally with a piece of metal cherry  undoing all the goodness of a great pudding !

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Inserting an ICD  for  DCM  may a be great therapeutic success  for the physician  as well as the patient . But there is one big truth hidden behind the statistical screen.

Following  study  provides dramatic data from Maanhiem in Germany in about 561 patients who had ICD .The long term patient outcome after appropriate shocks were much worse  than those without    shocks .This was more pronounced in Ischemic DCM .

appropriate and inappropriate shocks ICD

Source : Streitner et al ,University Medical Centre Mannheim, Mannheim, Germany PLoS One. 2013 May 10;8(5):e6391

The fact that these patients continue to throw VT , some thing is wrong in the cellular  milieu or a fresh scar / fibrosis / ischemia is progressing .Further , the VTs and the  subsequent  shocks  set in temporary  hemodynamic instability .We have evidence , EF can be depressed for days  worsening the long-term out come.

While it is easy  to blame it on natural course of DCM , there are  solid reasons to believe  , shock induced myocardial damage is definitely contributing to this  excess mortality.

One important  clinical tip is to screen  all  these so called Idiopathic DCM  patients  who  had appropriate shocks.  They should be monitored for fresh signs of any systemic illness  , like a  connective tissue disorder , chronic granulomatous lesions  like sarcoid etc .To our surprise  some specific  myocardial disease may unmask themselves in the natural history. Identifying them may offer a dramatic cure .

Final message

Some where along our EP mind-set  we are conditioned to think  , as along as there is an ICD in situ and it appropriately  shocks, every thing is bliss ! Blame it  on semantics . The  word “appropriate”  inappropriately  soothes  our nerves.

The fact of the mater is , every appropriate shock is a  grim reminder  that the heart  in question  is restless electrically and VT continue to emanate  from diseased  myocardium  . It could  mean either the LV   is destabilising  , or the original  disease  is   progressing  or a new disease  is evolving .

Mean while, paradoxically , inappropriate shocks give us a quixotic comfort , since the  heart is not really  throwing any dangerous arrhythmia, after all it is  the device related  false alarm   that  could be easily  reprogrammed!

Reference

ICD appropriate and inappropriate shocks

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Reperfusion arrhythmia was described originally  in the thrombolytic era .

It can be any of the the following .

  • AIVR(Accelerated Idio Ventricular rhythm)
  • Sinus bradycardia (In Infero posterior MI )
  •  VF can occur as  Re-perfusion  arrhythmia.

Does these arrhythmia occur following primary PCI ?

It should  isn’t ? 

In fact it  must be  more pronounced  as we  believe PCI is far superior modality for reperfusion !

Busy Interventional  cardiologists  of the current era  either do not  look for it or fail to document it . These arrhythmias occurs only  with early Primary PCI (Say less than 2-3 hours) .If re-perfusion arrhythmias are  really less common with primary PCI , are we missing some thing ?

 

 

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Fractional flow reserve(FFR) is an  Intra coronary hemodynamic  parameter  promoted recently to assess the physiological impact of a coronary lesion . Though it sounds logically attractive the concept  is sailing in rough seas  .I am afraid FFR is drowning  a fairly useful tool of IVUS  along with it  !

Read this large study on FFR (JAMA June 2014) .It seems to suggest  FFR is a costly and unnecessary accessory in cath lab

Image

Critical thoughts on FFR

It adds time , money , and procedural risk*  to any given patient .The only possible use is to reduce the proliferating stent usage !But the  irony  is complete as we do our daily business in  modern cath suits .To negate  one indulgence we need to  need to indulge  in  another ! (Junk begets Junk !)

It reflects lack of courage on the part of cardiologists to advice medical management even in obvious low risk lesions !

It is unfortunate ,we need a scientific or  a pseudo scientific tool to lift up our sagging medical intellect !

 

* crossing  delicate and often complex lesions  without any major purpose is bad wisdom !
(more…)

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LV ejection fraction (EF) is the most commonly used  LV systolic functional index.Since , it is an  easily acquired parameter,  it’s popularity has zoomed among both learned and novice cardiology professionals .(Not withstanding the serious shortcomings!)

In one of the evening rounds  in my CCU , a young cardiology fellow told me about a  patient  with acute  anterior MI with ST elevation V1 to V5.

The patient  was lying supine with trunk up . HR was 110 . BP was  100 /70 There were few basal crackles .The patient was undergoing  lysis with streptokinase.

It was  suggested  to me by the  fellow  that  the patient is  going in for “Impending  cardiogenic shock since his EF is just 30%”

That prompted me to ask this question

How good is the EF  a measure  of size of MI during STEMI ?

EF during  STEMI  is highly variable parameter.The following are important con-founders in LV EF measurement during STEMI.

 

  • Acute ischemia induced LV dysfunction .(Ischemic stunning from  the watershed zone  significantly over estimate LV dysfunction)
  • Mitral regurgitation  if present will underestimate it
  • Effect of tachycardia and bradycardia can be significant
  • The posture of the patient and  measurement errors (A good Simpson score is rarely  possible in a sick patient )
  • Associated  hemo -dynamic drugs like NTG/Dopamine etc which alter  pre and after load   and changes the frank starling forces.

* Please recall  , LV EF is never included as a criteria to diagnose cardiogenic  shock, confirming the  flimsy  nature of this parameter during acute phase of STEMI !

Final message

The purpose of echocardiography during STEMI is to rapidly identify any mechanical complication , not to waste time in calculating EF.

EF is not a good indicator  to  quantify the extent of STEMI  or it’s prognosis. LVEF cannot be used  to risk stratify STEMI in the first  48 hours .One can expect  the true LV function  to prevail only  at discharge.

Ideally ,LV  function should be reevaluated by 2 weeks to get a fair idea of true myocardial function .By this time all  confounders will resolve.

Clinical implication

Since many of us are suffering from an academic obsession and blindly follow the scientific guidelines, a hurriedly diagnosed  “severe”  LV dysfunction post STEMI may land our  patients to  inappropriate intervention !

 

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Pharmaco Invasive approach (PIA)  is the new mantra in the management of ACS.It simply means the intention to do PCI   should always  be the  driving force in every STEMI patient , whether the Initial lysis is successful or failed .

This concept is exclusively created  for centers where there is no cath lab (This would include  hospitals  with  inactive labs ,  cardiologist  team  who lack required expertise !)

What to do after lysis ?

  • If  the initial lysis has failed  “Rush” them  for an emergency  PCI.
  • If  Initial lysis is successful  “Send”  them for PCI in a  less emergent manner.

Generally the  time window for PIA is 3-24 hours.  In failed lysis  technically it could be as early as 1 hour as that is the time to assess the efficacy of initial lysis. (Of-course the theoretical transfer  time to be added )

Why the 3 hour period for PIA ?

We know routine   facilitated-PCI(f-PCI)  with various combinations of  fibrinolytics  and 2b -3a antagonists is a failed concept. (FINNESS )

One of  the primary reason for f-PCI to fail is , the  very narrow time window  between drug and balloon which somehow  end up in more hazard  (Needle -Balloon window)  .

If they are very close the harm is likely to be more ,still they have to be closer if lysis has failed .(This is the reason many old studies had depressing results with even with the  concept  of rescue PCI !)

Lytic agents and PCI  even though we assume to compliment each other real world evidence indicate they share a love hate relationship .

 

Beware, PIA is one form of facilitated  PCI.

If we agree routine  f-PCI is a failed concept we are in for real trouble. PIA indeed may  masquerade as f-PCI  if  you combine lytic and PCI in sequential fashion in a hurry !

My point of view is is a  successfully lysed STEMI should not be rushed to cath lab .If  he  some how reach the  cath lab ultra fast manner , it behaves like a  f-PCI and he is going  to harmed more !  by the current evidence base  isn’t ?

If the  inital lysis was successful , with a  less complex anatomy, it is  possible your PCI  that is going make the lesion more vulnerable.

(The other  issue is tied with flawed human instinct. One can’t stop with CAG in a PIA* .Interventional  cardiologists rarely have the courage to leave a well recannalised IRA  without PCI.)

**Still , you need to facilitate the PCI in complex intervention in  true rescue situation.That’s were we require the collective wisdom.

Assumptions galore in ACS

We have difficulty in  identifying true success and failure of lysis .Vagueness with which we make decisions  in CCUs and cath labs  , is exemplified by the following facts. Post thrombolysis , 40%  patients with persistent ST elevation are asymptomatic and 30 % of all those with complete  ST regression , still have occluded IRA.

We are also uncertain when do  the muscle  truly  die after a STEMI ! It is 6 hours in some, 12 in many, 24h  in few , 36 h in a lucky ones .The role  of collaterals, intermittent patency , individual variation  resistance to myocardial hypoxia injury cannot be  be quantified .

Final message

  • The importance of Needle to Balloon  time (NBT) time in PIA  is to be strongly emphasized.
  • This time can vary between 1-24 hours .But practically it will start from 3 hours .
  • The irony is , we have conflicting  engagement with time in PIA. We have to  strive for both narrowing as well as intentionally  prolonging this time window .
  • It has to be narrowed in true rescue situations and   optimally prolonged (Or is it indefinitely ! ) in non rescue situations !

After thought

Can we do pharmaco-Invasive approach(PIA)  in PCI capable center ?

  • Even in PCI capable centre one may get struck in proceeding with anticipated primary PCI for various reasons . If delay is anticipated we  have to fall back on thrombolysis .This we call as  unscheduled  or bail out  phamaco Invasive strategy .
  • Intentional PIA   in a PCI capable hospital for all low risk MI is also a viable and option .Never think  primary lysis   for STEMI  even if we  have lab ready is serious medial crime . After all , pPCI has a very  marginal benefits in if any in all low risk STEMI!

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CHB with CAD is a  common combination especially in the elderly.

Which will you Intervene first ?  Is the AV block related to CAD  ?

How to differentiate Ischemic from degenerative AV block ?

Differentiating is often difficult.Even coronary angiogram may not answer the query unless it is totally normal . For AV block to occur usually  LCX / RCA lesion is required.  LAD lesion in isolation are rare to cause CHB .

How often re-vascularisation  reverses  ischemic CHB ?

Logically  you expect more reversals.In real world it rarely happens.

Therapeutic options in combined CAD and CHB

  1. PCI and pace maker in the same sitting .
  2. PCI first followed by pace-maker at a later date.
  3. Pace maker first followed by PCI at a later date if required.
  4. CABG  and epicardial pacemaker ( best option In all critical TVD and CHB)
  5. Pace maker followed by CABG later
  6. Pacemaker followed by medical management (CHB with Insignificant CAD)

Can worsening of ischemia  occur after pacemaker  ?

Very much possible . Since the patient  has been benefited by low heart rate in terms of MVO2 consumption .(Inserting a pacemaker  is  like sudden withdrawal of beta blocker !)

Rate adoptive pacing can confer chronotropic competence which  may bring back the angina.So,what was a insignificant lesion  can become hemodynamicaly relevant  and  may require  angioplasty  later.

*The above clinical issue is applicable  for sinus node dysfunction and CAD as well.

Final message

There is no  fixed rule in the management strategy in combined  CHB and CAD .

Generally , electrical  therapy  should be given preference .Symptom guided approach  may be practical.

In this scientific era , one may argue to deal both issues  together by simultaneous  PCI and pacemaker ,  still  option 3 and 6  remain clear  favorites !

If angina  occurs  even in  baseline bradycardia  it is obvious the obstructive CAD  is  significant and needs immediate fixing .

Finally , though it looks an attractive  concept , It is very rare for CHB  to get reverted by PCI or CABG.

 

 

 

 

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Last week  there was a heated debate in our CCU regarding thrombolysis for  a patient with severe rest angina  and ST elevation in AVR  and ST depression in V2-V5  as it implies  Left main disease  Few argued left main disease is an exception where one can thrombolyse even with unstable angina !

One of my fellows argued ACC guidelines vouched for lysis in UA involving left main .( I do not agree )

A logical attempt to differentiate Left main NSTEMI//UA and STEMI

(In the strict sense Left main NSTEMI is misnomer as AVR shows ST elevation  isn’t ? )

left main disease

Final message

Such  patients with suspected LMD   are to be rushed to cath lab .  . . agreed . If it is not feasible , manage it as high risk unstable angina and do not thrombolyse .Let it be left main disease . Indications for lysis are clear. ST  elevation in AVR alone can not be taken as an Indication for lysis.For thromolysis to be effective there should be high thrombus burden with total occlusion . ST elevation in single lead (AVR ) is not a good  marker for left-main thrombus !

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