Archive for August, 2013

I wish to  be in New Zealand , not only because of the stunning  natural beauty but also to pay tribute to one of the great  cardiac surgeons  of our time from Auckland .
An alluring  country side cricket ground  abutting the runway  . . . Queenstown I think !

Sir Brian Gerald Barratt-Boyes (1924-2006), Who pioneered all forms of  heart surgery that  specifically included  complex congenial heart disease . Thousands of Kiwi   children are alive and leading a  magnificent life today  because of this  man from Green lane an alumni of Mayo .

barret boyce tof intra cardiac repair cardiac surgeon

Many heart surgeons from India and Asia pacific have trained under him .


Green lane Hospital Auckland.

This is the  hospital where Barrat Boyes worked headed the department of cardiac surgery .He had to over come large bureaucratic hurdles before becoming world ‘s leading cardiac surgery center. And , he lives everyday  in all cardiac units   through this book .

barratt boyce kirklin

Here is a link to pay tribute to this extraordinary man.

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I’m trying to get  a right  answer for this question for quiet some time. The literature on lipids is so vast  , one can never finish reviewing it.There are   nearly two dozen journals that  deal with lipids ,Atherosclerosis, obesity ,and vascular biology .

Yet  , the answer to this simple question is elusive to us .The Irony is complete when we have evidence for   two diagonally  opposite responses 4 and 5 .

My interpretation of the issue

Any lipid molecule if exceeds a critical  level ( Only  if   . . . associated with hypertension, or diabetes or smoking ) can penetrate the vascular endothelium. ( HT-pressure injury , Smoke- Endothelial dysfunction  due to Nitric oxide depletion) DM -Glycation of cell membrane  , finally some  unknown inflammatory component )

Though evidence  for direct endothelial  injury is more for LDL ,  less for TGL (Almost nil  for VLDL , but  TGL has more VLDL in it !)

Strangely ,these molecules , express a mob psychological behavior .In isolation they appear innocuous. But ,in an  unfavorable   setting it shows signs of  revolt. If a group of  LDL molecule start attacking a  dysfunctional segment  of endothelium , the other molecules  like TGL and VLDL fractions would love to join the crowd  and inflict further  damage . (Of course ,the lonely HDL may watch the chaos silently !)

Questions to ponder

If LDL is a sharp knife like molecule  trying to injure the blood vessel , every normal human being is potentially threatened  by this  lipid fraction . Mind you,  this is a physiological molecule  traversing the human vascular system  at concentration  of 130mg/dl  at the  velocity of blood .

So it is  foolish  to blame this  physiological molecule for all our ignorance.

I recall one recent definition for hyperlipidemia

The lipid levels at which a patient develops vascular injury is considered high for him !

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Of late many drugs are entering the  market  for human  consumption backed up by  Non -Inferiority trials (NIT ) .Few examples.

“The ONTARGET trial: Telmisartan is non-inferior to Ramipril in  New Study Results Published in the New England …”

Feb 20, 2013 – in the New England Journal of Medicine Show Dabigatran Etexilate ... daily was non-inferior to warfarin (p=0.01) in preventing recurrent VTE, …”

What is the logic behind these  Non inferiority trials ?

Why it came into vogue ? 

Do you agree with the concept of NIT ?

I have taken the  privilege  of putting my answer in the title. Believers  of NIT please excuse me.


Non inferiority drug trial

Non inferiority drug trial 2

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Cannon waves occur when Atria contracts against a closing tricuspid valve of  right ventricle .( There  would be a equivalent left atrial cannon which  goes into pulmonary vein as well  , it is discussed elsewhere !)

Cannon waves  happen only when P waves fall within QT interval in ECG as QT represents the electro-mechanical systole of  ventricles.  (Since P wave represents atrial systole , it is simple to understand when it falls within QT both atria and ventricular contractions collide to produce a cannon wave into the neck or pulmonary veins.)

The following two images of cannon waves  taken from the legend  Dr Paul woods own tracing  .

irregular cannon waves in jvp  complete heart block

regular cannon waves in jvp  svt avnrt  11 va conduction  002

Regular cannon waves

Occur during SVT  with 1:1 VA conduction.*

1 : 1  VA conduction  can be considered as  absence of  AV dissociation  (Rather  disciplined  VA association with every beat ) This is essential to create a hemodynamic  milieu for regular cannon waves.

* In AVNRT , VA conduction in strict  sense  is a misnomer  .It is simply a retrograde conduction thorough  the AV node .

Irregular cannon waves 

  1. Complete heart block .
  2. Multiple random VPDs
  3. Some patients with VT.*(Who are those patients ?  Those with AV dissociation when retrograde “P” wave falls  within QT interval cannon occurs. As expected this occurs in random fashion  which makes  the cannon fire irregular.

Can we get regular cannon in VT ?

Yes , but rare . As explained earlier this can happen only if AV  association occur on a retrograde fashion.

Further reading in this site

What-is-a-cannon-sound  , how is it related to cannon wave ?

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PTMC is a revolutionary    interventional cardiology procedure .A fibrosed obstructed  mitral valve is  opened up just like that , with few wires and a balloon  .The procedure  performed within 30 minutes .No  anaesthesia . No surgery .No scar.

Thousands of procedures are done world-wide (Rich countries excluded    they do not have RHD) .We in our institute , have gained considerable experience in PTMC ,  and  have  completed  nearly  200 procedures  in the last  few years .

As we gain experience surprises also galore ! .Suddenly I realised this  funny (At least for me !) phenomenon  from the unique PTMC balloon design.

The other day  , there was an intense argument between two of my  fellows , who were in a dispute  .One was arguing  , the PTMC  balloon  had dilated the tricuspid valve erroneously  while  other was adamant , and  wholesomely convinced  , since the waist  had disappeared it must be the stenotic mitral valve.

The issue came to me  . . .  ended after a nice  debate !

PTMC balloon accura Inoue waist mitral stenosis percutaneous mitral commissurotomy .

Both PTMC balloons  (Inoue ,Accura) are made with innovative design  conceptualized by Japanese genius Kanji Inoue . The balloon has two layers of latex with a nylon mesh sandwiched in between.The latex  is compliant while nylon limits  it  and generates the required pressure .

The balloon is glued in a such a way ,  central part is  constricted  like narrow band .This makes sure the distal part of balloon inflates first , followed by  the proximal and finally the central .This  also help us  to  geographically to fix  the balloon across the narrow mitral valve orifice .

While , we must agree  this a great  concept , there is an an inherent issue when handling a hour glass shaped balloon with a  natural waist .There would  be great deal of confusion when we take disappearing waist as an index of relief of mitral stenosis.

We know ,the key  requirement is that ,  balloon’s waist  should match anatomical MVO .But , it is estimated  exact match  happens in a minority.  The issue gets further complex  with  subvalvular disease , double mitral orifice, eccentric orifices . The efficacy of PTMC is also determined by the appropriate contact of the balloon’s various pressure points . ( It is a balance of intra balloon pressure(3-4 ATMs)  and  the surrounding tissue pressure !)

Disappearing waists is not synonymous with opening  MVOs .All PTMC balloon inflations will shrug of the waist at peak inflation wherever you inflate .(Intra chamber inflations included !)

Final message

Please realise ,  falling pressure gradients and echo  documentation of  MVO  rules supreme  in assessing successful PTMC. Often times , disappearing waist  is  meagerly an optical  Illusion or gratification.

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