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Archive for November, 2014

Brugada syndrome is due to a genetically  impaired  sodium channel activity  ( SCN5A)  in phase o, of action potential .This results in phase 1 (Ito channel) failing to inscribe the transition between phase 0 and  1 that result in loss of  dome .This loss of dome is dominant in epicardial cells compared to endocardial cells.This result in  electrical heterogeneity and a hence a voltage gradient in repolarisation phase  that can trigger a Phase 2  reentry mediated  VT /VF.The above said defects are either dormant, manifest, self extinguishing , dynamic  subjected to autonomic tone , ambient myocardial temperature (Febrile VTs) making this a complex entity.

There are three distinct types according to surface ECG.It can be either spontaneous or induced. The arrhythmic events and prognosis and hence management differs according to the types.

mechanism of brugada syndrome three types of ecg 2All types carry  a minimal risk of SCD , variable though . Of course  syncope  has to be  much more  common. Curiously every episode of syncope is seen as naturally aborted SCD by physicians ! (No one  to be blamed for this .The definition of syncope is like that !If the patient doesn’t wake from syncope it becomes death !).

When a patient with Brugada  has a  syncope , it  doesn’t  imply  he  experienced a dreaded VT or VF.While SCD is invariably due to ventricular fibrillation , a spontaneously terminating VF  as a cause for syncope is rare in Brugada . (Ref 2 : ILRs have documented though in few)

So what exactly is the cause for syncope in Brugada ? The issue is  real  and critical in clinical decision-making. We are beginning to document variety of mechanisms. Following are the possible causes

  1. Sustained  VT or NSVT with
  2. Non sustained self terminating  VF
  3. Extreme bradycardias (Vaso vagal )
  4. AV blocks
  5. Unrelated neurogenic

Final message

It is to be strongly emphasised a significant subset of Brugada patients especially in Type 1   Brugada (spontaneous or drug induced )  the mechanism of syncope is often not related to the dreaded VT/VF. It can simply represent high vagal tone and unexplained dynamism of autonomic activity .ICD is not a default indication for all those with syncope in Brugada syndrome.Think , pause and decide when you deal with such patients. ICDs are true revolutionary devices  . . . no two thoughts about it,but it can make a hell out of heaven if used in an inappropriate situation !

Reference

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Human beings can defy fate  in a regular fashion as the  modern science is exploding and creating   infinite possibilities !

  • We can give a fresh  life to a dying man by  multiple organ transplants just like changing  a crashed mother board in a PC !
  • We can isolate vital germ cells , fuse them, clone them and even  create new form of life !
  • We can  keep a man in deep coma  for years and bring back to life !

Still , a sudden cardiac death that happens in a remote place in an unexpected manner is still in the God’s domain ! Cardiac arrest and sudden cardiac death is the  most common mode of acute human loss in our planet .(Read a link :Ignorance based cardiology )

When  the heart goes for convulsions due to electrical  instability , the only solution is immediate  CPR followed by electrical shock .All you require is about 200 j of electrical energy over the chest .This is to achieved within 5-10 minutes.How and where do you get that energy in that short time span ? Is 911/108 services that efficient ?

*Can your fully charged  mobile phone  deliver it ?  Unfortunately not yet !

Public access AEDs (Automatic external defibrillator) are there in many  commercial places.But ,they are not  universal and foolproof.

Come 2015, we have a marvel of a technology waiting  to happen !

How about delivering  a light weight  defibrillator through a drone  ?   to the exact place where it is needed .With the accuracy of GPS  technology  steadily improving , a self powered , auto- responding drones from a near by base station  is a reality .

flying defibrillator aed sudden cardiac cpr

This drone . . . delivers life !

All that is required is a phone call . The drone with defibrillator is  delivered  in few minutes .Of course , a bystander help is required .An experimental pilot project is being tried in Holland What a break through it could be when  its stream lined ?

Man proposes ,God  disposes ” so sure it is !  Are we close to challenge the super power ?

It is said , modern men will play god in near future with perfection.Can it ever be like this ? “God proposes and  man disposes ?  No . . . it can never be!  If a drone comes from nowhere to save a human life, it is also an act of God ,through a   “Human enriched  technology.

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VSD with Pulmonary atresia is a complex form of cyanotic heart disease .Though it’s  a close  companion of Tetrology of Fallot  physiologically, it is a vastly different entity in embryological and anatomic terms.

TOF is cono truncal anomaly where abnormal anterior displacement of conal septum result in malalignment VSD, RVOT obstruction ,aortic override and RVH.

While ,pulmonary atresia with VSD  is not a primary cono truncal anomaly, the defect occurs much earlier than TOF in fetal life , where the origin of PA fails to materialise,(Fetal arteritis?) and which triggers a series of anatomical disarray in pulmonary arterial circulation.  The PA growth arrests in various levels (Somerveille Types) .It is important to realise while the PA may be patent , pulmonary valve is always atretic and disconnected from RV.

In severe forms there is Zero pulmonary artery content .The lung is perfused in chaotic manner. This situation akin to “TAPVC” in arterial side  and result in  total anomalous pulmonary arterial connection.

pulmonary atresia vsd mapcas major aorto pulmonary collaterlal unifocalisation single multiple stage tapac

Natural History of PA with VSD .

The blood supply of lungs is maintained by  MAPCAS.Since , the  fetus is not dependent on its lung for survival,  life goes on well , till  birth  and face the harsh reality that  it has no independent blood supply for  lungs from RV  and has to depend on collaterals from aorta.

Survival depends upon the  the quantum of collateral .( Size , number, arborisation pattern etc). Life is shortened in most babies and  lost by 1 or two years . Exceptions are always there.Survival has  been reported up to third decade in a few with a balanced pulmonary flow.these are the ones we catch up in young adults some times.

In effect , MAPCAS are the life line of these children  , paradoxically  the  fate of these children  piggyback  on the  behavior of the MAPCAS .

MAPCAS  are not natural vessels that is  meant to receive blood at  systemic pressure. They are fragile and thin and when exposed to high pressure react pathologically.

Following anatomical and physiological effects occur in MAPCAS .

  • Collaterals  fail to grow with child
  • Obstruction to  MAOCAS can develop(Often at ostial)
  • Collateral can be extensive causing pulmonary vascular injury.
  • Regional and segmental pulmonary arterial HT can occur
  • MAPCAS can suddenly rupture and cause fatal hemolysis
  • Collaterals perfusing more than normal resulting in volume overload of LV and failure

Principles of  Surgery

The principle  of surgery is to disconnect the arterial   pulmonary  vascular  blood supply and connect all lung segments with pulmonary  arterial supply and ultimately connected  to right ventricle to restore the physiology.

Single vs Multiple staged surgery

The original  concept was to do multi stage surgery , believing in the principle every stage give us time for pulmonary vessels and lung  to grow .It involves extreme commitment of surgical team in identifying and understanding the pulmonary  vasculature and the systemic collateral arborisation. The factors that is taken into account includes the presence of confluent PA , MAPCAS induced lung segment injury  and its maturity . When pulmonary vessels are inadequate , autologus  pericardial rolls are used as alternatives.

There is no point in vascularising  a zone of lung  with  physiological  low pressure neo pulmonary circuit which is unlikely to  to work because of immaturity of distal veesels  or its  already damaged by the harsh pressure of MAPCAS!

We have realised the  hemodynamci behavior of lung segments supplied by  MAPCAS and the subsequent undoing of it  is so unpredictable. The current concept is to recruit maximum  lung segments  and aim to provide revascularization through  physiological manner.

An early single stage unifocalisation is  suggested as a best option.(Reddy VM, J Thorac Cardiovasc Surg. 1995;109:832–45). Single stage repair is attractive not only in long-term  hemodynamic advantage but also  in the  logistics . In multi stage repair ,only about 20-30% of children ultimately complete the treatment for various reasons.

It is heartening to note one of huge accumulated experience for surgical management of PA with VSD has happened in the  southern Indian cities  of Chennai and  Hyderabad where i live.

Kudos to Dr Murthy and team for the pioneering work .Incidentally ,Dr KM Cherian is the legend in the filed of cardiac  surgery and in my opinion  he should get the title of the Father of pediatric cardiac surgery in India !

And  this seminal paper from his team  shares  one of the largest  experience   who underwent single stage  unifocalisation for PA with VSD in 124 patients.

tof vsd with pulmonary atresia unifocalisation

What is the cardiologist  role in VSD and PA ?

Cardiologist are expected to play  a limited role . They can’t provide any cure as such.A meticulous cath study is all that required from them for the surgeon.

Selective  MAPCAS angiogram  requires special expertise ad through knowledge of anatomy .The MAPCAS are clustered around few specific  zones.Now MRI and CT scan also can delineate the anatomy.

What is the  surgical outcome ?

it is steadily improving globally.But only a hand full centers in the world can undertake such complex procedure(Lucile packard Children’s hospital Stanford is pioneer )

Hemoptysis in PA and VSD

It is a rare but an important issue .This can occur any time in the natural history even post operative. Most are managed conservatively .Interventional approach with embolisation is possible in expert centers.(K.Greaves et all)

Can  the  natural history be better than these complex unifocalisation surgery in these tender children ?

Statistically , it is possible in few cases, but to identify those children you need to get an appointment with God ! If parent’s take such a decision it should be welcomed and cardiologists and surgeons  should not lure them with scientific excess !

Final message

The surgical correction of PA with VSD continues to be complex .Meticulous  recruiting and unifocalisation of PAs and creating confluence , connecting the RV through a conduit may be the key.However, ultimately  what is going to matter is the how the lung responds to these surgery  hemodynamically !

It appears to me the whole process is  more of a vascular surgery of lungs rather than  heart !

Reference

  3. An excellent resource on MAPCAS  from Sao Paulo , Brazil
pulmonary atresia mapcas vsd unifoclisation confluence direct and indirect aorto pulmonary rabinovitch

 

 

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Complex coronary lesions require  not only  expertise it needs better hardware .A key  factor is the support from  guide catheter.Innovations are hall mark  Interventional cardiology community.Every few years a hard ware breakthrough is expected.

Boston scientific has an answer for improving frequent guide catheter destabilisation in complex anatomy and lesions .A dramatic new concept for guide catheter support .They have named it  in a hollywood fashion “Guidezilla”

Major advantage : Extending the tip of the guide with an anchor to  facilitate smooth balloon approach to the  lesion which  i avoids repeated disengagement of guide catheter.

Watch this animation . It comes with a music stunning too !

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In this wireless networked world nothing is personal, not even your heart beat.Modern pacemakers and ICDs have wireless connectivity with the manufacturers.This is value added service for regular monitoring and solving  any technical issues.

assets_174815Hacking  a device like pacemaker and ICD  and instant deactivation or triggering a new event   is a distinct possibility .It was shown in a fictional TV series “Home land” that prompted the  ex American wise president Dick Cheny to switch off all wireless function in his ICD. Now ,the US homeland security  cyber emergency  response team has decided to probe the issue .

pacemaker hacking icd

Perils of technology is taking us to new uncharted territories , while your  SA   AV node are at risk of being  remote controlled !

Meanwhile Medtronic has clarified they have increased the security features and pacemaker /ICD hacking is not an issue to be worried . But the threat is genuine !

Reference

1. Frenger P Hacking medical devices a review – Biomed Sci Instrum.  biomed 2013.2013;49:40-7

3.Fox news

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When  I was suggesting a middle-aged business man who has suffered a massive MI,  though recovering   he seemed to be a depressing man.He was  still fuming about the illness.

I told him he has  in fact recovered faster than others , he has  to believe  in himself , concentrate on his work  and take these medicine regularly .Finally , I told him to develop the will power which is vital,

will power

After the scheduled consultation , he thanked me , before leaving  he asked me candidly and jokingly   ,every thing is fine doctor ,  which pharmacy sells that will power ?

I stopped him at the door , “It is  not sold  anywhere , it is  lying  dormant  right inside your brain store . You have to just do the shopping , which is open 24/7  and best  part is it is always available free of charge and unlimited too !

drugs and thoughts modern medicine psychology mind power healing faith will power 003

I  advised him to have a look at the  Speaking tree  from Times of India which has  so many resources and surely he can acquire will power  in  plenty !

speaking tree

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Aorto ostial  stenting requires extra caution and special technique. It always  worry us  what if  few mm of  metal might project into Aorta when we stent a RCA or left main ostium.

To  prevent this ,Merit- medical  has innovated a catheter that help us position the stent exactly at the ostial level .It is  done  with a help of an octopus like buttressing arm that support the aortic wall when the stent is deployed .

Watch the video.

 

Reference

Merit-medical 

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