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Archive for the ‘ICD -Tips and Tricks’ Category

ICDs are one of revolutionary devices , invented last century  that can defy “death & fate”  in high risk cardiac patients who are threatened with ventricular tachycardia or fibrillation .A decade long hard work by  Mirowski  and team from John Hopkins culminated in the dramatic  the first AICD implant in 198o. ( In my opinion, this medical invention can be compared to an event of such  significance as moon landing by Armstrong and team ! ) Ironically , in the last decade such a revolutionary device was sort of misused and thousands of devices were explanted for inappropriate indications.

Fortunately , better sense prevailed recently .The indications are getting  refined. I am sure ICD will go a long way in prevention of  both expected and unexpected sudden  electrical deaths .We are into  the 4th decade of its evolution.While the electrical circuitry has been mastered , power supply remains an issue as they require continuous power supply like a mobile phone. Current technology allows about 6-8 years of battery life.

EL-ICD boston scientific longest life icd smallest profiale dynagen inogen madit indication for icd

Now , Boston scientific  has come out with new technology which make its  battery life extend  by 100%  to 12 years.  It is a major break through , expected to evolve  further  until probably we have rechargeable  batteries or biological power sources .Stretching a wild thought , the days couldn’t be far off  when the smart phones which are omnipresent in every human-being  , could not only power the ICD  remotely and control it too !

 

Indications (ESC/AHA 2012)

CAD

  •  Post MI* /LV dysfunction  ≤ 35% /NYHA   class II or III  (*  > 40 days)
  •  Post MI* /LV dysfunction ≤ 30% /NYHA Class I (* > 40 days )
  •  With non-sustained VT due to prior MI, LVEF < 40%, and inducible VF or sustained VT at  EP study

Non ischemic structural disease ( Idiopathic DCM, ARVD etc)

  • With structural heart disease and spontaneous sustained VT, whether hemodynamically stable or unstable.

Primary electrical disease

  • With syncope of undetermined origin with clinically relevant, hemodynamically significant sustained VT or VF induced at electrophysiological study

 

Reference

Link to Product manual form Boston scientific.

Boston scientific

 

 

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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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