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What is right for left coronary artery could be wrong for “Right” !

Posted in Cardiology -Interventional -PCI, Cardiology -unresolved questions, Hemodynamics, Infrequently asked questions in cardiology (iFAQs), Uncategorized, tagged , , , on November 27, 2010| Leave a Comment »

Coronary circulation is an enigma . This is true even after 50 years of coronary angiography.  What we visualise  in CAG is  only a  fraction ,  when  compared with what we do not see !  The intricacies of  coronary collateral circulation and micro circulation is comparable only to the  ultimate force of   invisibility “The  God ”

But , we will never ever believe what we do not see  . . .  but we have to accept the following  fact . How is it possible   for  some of the coronary  arteries  to maintain  a near normal blood flow from a donor (Contralateral ) coronary  artery  in spite of  100 % occlusion ?  Is it not common to see TIMI 3 flow even with 99 % occlusion .(Link to related article in  this blog  and  video ) . This is because the coronary  vascular bed has an extraordinary capacity to drop its distal pressure to negate the effects of obstruction.

Does the distal vascular bed anatomy and physiology same in RCA and LCA ?

We presume it so . The problem in medical science  is , these   presumptions  often  become  facts in due course  ! Now we have (It is in fact 30 years old !) RCA has lesser ability to withstand the stress  of stenosis than LCA.

The prime reason for this observed difference could be the LCA has a well developed microvascular bed which can reduce the distal coronary resistance .(Again , this is my  presumption  . . . !!! )

This interesting article was published in Circulation 1980 .



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Lesser known cardiology journals : “Heart view” – A treasure from Qatar !

Posted in cardiology journals, Great websites in cardiology, Uncategorized, tagged , , , , , , on November 27, 2010| Leave a Comment »

Great people  do not boast  . While there are thousands of hyped up publications in cardiology ,

This one form Qatar excels , which  I  stumbled upon recently  contains very useful information about wide ranging issues in cardiology .

Let us congratulate the   Hamad medical corporation for  their unique  academic vision  .

http://www.hmc.org.qa/hmc/heartviews/ARCHIVES/ARCHIVES.HTM

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Medical Kick backs : Watch dogs are sleeping and they are unlikely to be awakened !

Posted in Uncategorized on November 24, 2010| Leave a Comment »

That was a slightly  modified title of an article published by the renowned Nephrologist from India Dr.M.K.Mani

Who is also involved in the fight against live kidney bazaar  in India.

In this article he shares  his experience  ,  how   desperately he is  trying to correct a major conflict in physician laboratory nexus in India . It is has been an  elusive search for  the past 15 years.

And  the article  seems to the conclude  , there is no other option   , we (And our patients )  have to live with it .

But , what we need to realize is  we have our own  watch dogs lie within our mind , and it need to bark every time a thief is seen .

Let us awake our self for the benefit of our patient kind .

By the way , how many  among us know such an important journal is published from India !

http://www.issuesinmedicalethics.org/044ed105.html

Further reading

No doubt ,  such kick backs and gifts and ads make medical care artificially high and unaffordable.

The pathetic stories of how modern medical care create new breed of  poverty.

the poor can not get even the basic  treatment because they are poor  , while  the rich get costly and  inappropriate  some times dangerous treatment and become poor .

Link to The WHO article that exposes the Issue

I know there is  a book written by Dr M.K Mani ,  Yamarj’s Brother

I have not read it .I wish i get it soon .That Iam sure will enlighten us

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Anticoagulation protocol in pregnancy with prosthetic valve

Posted in cardiac drugs, Cardiology - Clinical, Uncategorized, tagged , , , on November 16, 2010| Leave a Comment »

A simplified animation strictly  meant  for understanding the concept

Link to the review article on the topic

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Bi-phasic DC shocks : It is different !

Posted in Cardiology - Electrophysiology -Pacemaker, cardiology -ECG, Uncategorized, tagged , , , , , , , , , on November 14, 2010| 1 Comment »

No one would have believed a century ago when electricity was first dosvovered  for the mankind by Benjamin Franklin  with glorious  purpose , would now  be used as a drug for treating  life threatening heart ailments  !

Yes , electricity is a drug by definition.

It is administered percutaneously  by focusing  a beam  of current into the heart.

  • There is a dose , shape , energy  and direction for this drug.
  • Paddle size determine the energy.
  • Paddle location determine the direction of  current vector.
  • Dose is selected by the  physician.

Mechanism of DC shock / Defibrillation *

When  heart suddenly behaves abnormally  and start generating its own electricity and sends it through abnormal channels other than its natural paths ,  it becomes a dangerous arrhythmia .This propagation of wave front can occur in multiple directions  in a chaotic manner , resulting in VT/VF and imminent death.

Like an air to air missile ,this  abnormal wave front  can  be tackled only by an another electrical  wave front . Nothing else will work.

* The difference between DC shock  and defibrillation is only technical. If one gives a  synchronised shock  ( with qrs complex ) it becomes  DC shock .If not ,  it is defibrillation

The success of defibrillation depends on many factors .

The following are most important.

  • The critical myocardial mass must be depolarized by the current delivered.Sufficient  amount  of sodium channels /less  of calcium  currents  need be activated for this to happen .(JACC 2008)
  • The direction  and the angle  of current entry with reference to  advancing  end of abnormal wave front. is also  important .
  • Distance between the paddles.(Antero posterior paddles more effective than Apex /Sternal pads )
  • Energy level (seems to be less important ! )

Two shock forms are used

  • Monophasic shocks
  • Biphasic shocks

A biphasic DC shock has  replaced the traditional mono phasic  sine wave  shocks in most machines.

What is  the  fundamental difference between the two  ?

  • In bi phasic  shocks , the current traverses the myocardium twice .
  • So, it has a second chance to interrupt the critical tachycardia  circuit , if the first one fails. In other words, biphasic shocks are  technically equivalent  to  “two  sequential low energy shocks”  delivered in opposite polarity . This change in direction happens in micro seconds .
  • The shape of biphasic DC current  wave form can be a truncated  sine wave or square wave .The maximum  energy of DC shock in biphasic mode  is  200 joules (In Monophasic it is  360joules) . All AEDs, ICDs, now use bi phasic shocks to conserve energy .

Final message

A biphasic shock waveform has a proven advantage . It has  greater efficacy ( because it traverses the heart twice ) , requires fewer shocks  with low  delivered energy and hence  less myocardial  and  dermal injury.

References

Even though there is general  acceptance of superiority of bi phasic  shocks ,  it is still considered by some ,  that there is no great difference in the  overall outcome .

http://content.onlinejacc.org/cgi/reprint/52/10/828.pdf?ijkey=5a8f50ff2542182c857d4f3fe553aef8df6e3fd3

http://circ.ahajournals.org/cgi/content/full/94/10/2507

Bi phasic shocks in atrial fibrillation

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1768486/

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The most important article on hypertension ever to be published :Loose cuff hypertension !

Posted in Cardiology - Clinical, Cardiology hypertension, Uncategorized, tagged , , , , , , , , , on November 13, 2010| Leave a Comment »

Blood pressure  measurement ,   probably  is the commonest investigation done  in our patients  in  the entire field of medicine . It is such a common thing ,  both physicians  and patients  fail to perceive  it as  an investigation . (It indeed is !)

Even though BP is  considered as a  clinical sign , measuring it requires a device called sphygmomanometer  . The BP apparatus has to be properly calibrated  with the mercury  , the tubing, the bladder  , inflation balloon  etc   need to be perfect.

The following fallacies are noted in the measurement of  blood pressure . Some of them are rampant* !

Patient

  • Posture of recording
  • Anxiety -White coat /Gender

Device

  • Cuff width/Length
  • Arm circumference

Ocular errors

It is surprising , such an important tool has a scale of 2mm markings which is prone for parallax errors of light with  mercury column undulating .

Physician factors*

  • Hasty cuff syndrome , Rapid deflation .
  • Absent minded recording – Failure to note phase 4 to phase 5  due to inattention
  • Failure to hear phase 4 muffling  (Aging  medico  -Auditory insufficiency !)

It is  not at all  surprising  to note,   two BP readings rarely match ,  even if it is recorded by the same person with  same machine at the same time !

There are many  articles that describe in detail  ,  how to record blood pressure properly. But this article from  a relatively unknown  journal   from Purdue university  ,  tells  us  most   scientifically  , what  has been taken for granted  by the medical  community for so long  .

Loose cuff  hypertension (Link to the journal of  Cardiovascular engineering )

How much  stiffness  is to be applied in  the arm for optimal pressure recording ?

What is the incidence of hypertension due to  loose cuff  ?

Final message

The BP apparatus ,  though appears  as  an   innocuous   machine ,   the readings  that emerge  from it  determines ,  how millions of our fellow human beings are going to be labeled  ! ( High pressured  humans ,  slaves to  anti hypertensive  drug marketeers    for  rest of their  life ) .

So , realise  how important  it is , to measure  the blood pressure properly    !  Never be casual . . . with  this  machine .

Experience has taught us ,  while  it is very easy to name an  individual  wrongly as hypertensive  , it  often needs  Herculean  efforts  to remove this medical tag from their neck . The reasonings  are  many .( Academic , non academic and patient factors included )

Finally , in this funny planet  it is  a personal observation ( Or is it  an imagination ?)    some  men and women   tend to  enjoy  ,   being  referred to  as  high pressured !   Loose cuff  or tight cuff   ,  it simply do not bother them  !

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Cardiologist beyond compare !

Posted in Uncategorized, tagged , , on November 12, 2010| 1 Comment »

Cardiology as  a specialty  has grown faster than any other field in medicine.  From  the days of  Da -vinci and  William Harvey  ,  the  urge to understand the  intricacies of  anatomy and physiology of this organ that sustain the rhythm of life ,   life was tremendous .

Heart was a gift of life  by God to the man kind

  • Few men dreamed about it.
  • Few were simply fascinated by it .
  • Some   exploited it in the name of science .
  • Only   few  spent the entire life  for it   ,  explored it  passionately . . . truly and genuinely .

One such person , we should all celebrate is Noble  O  Fowler  From Cincinnati USA. This unassuming  ,(In contrast to  some of the current hyped up  achievers !) has kindled thirst in the subject to many  youngsters .

His remarkable achievement included

  • The  pioneering thoughts about pre-infarction angina (Now labeled as unstable angina)
  • Pericardial physiology and pathology
  • A overall approach to cardiac patient with shrewed physiological and pathological sense.

His book cardiac diagnosis was a exclusively authored by him is still considered as unique as his life.

Some how this book never got published beyond the 1980 s.

I personally  dedicate this  little service to cardiology literature to the legacy of Noble O Fowler.

A tribute by his Collegue Robert J Adokph

 

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Rare encounters in echo lab : Abnormal right atrium and right ventricle

Posted in Echo library and gallery, echocardiography, Uncategorized, tagged , , , , , , , , , , , , , , , , , , on November 5, 2010| 3 Comments »

A female child aged 14 was referred for progressive breathlessness  and  abdominal distension

Abnormally dilated right atrium with significant pericardial effusion .www.drsvenkatesan.com

Can you guess the diagnosis ?

Apart form RA ,RV dilatation , the RV apex is seen filled with coarse treabeculations.This is believed to be a type of non compaction http://www.drsvenkatesan.com

Still difficult to conclude  ?   Look at the following Image.

Tricuspid regurgitation is significant . http://www.drsvenkatesan.com

If you have thought  . . .

  • ASD with TR
  • Severe PAH/COPD
  • RV cardiomyopathy

All are  acceptable  differential diagnosis

But the real diagnosis is none of the above .

Need  more time  . . . the following   Doppler tracing  will settle the issue !

Doppler velocity in RVOT at 88mmhg. http://www.drsvenkatean.com

The final diagnosis was . . .

  • Severe valvular pulmonary stenosis
  • Marked RV,RA dilatation
  • Acquired non compaction of right ventricle
  • TR -Moderate
  • Pericardial effusion -Moderate
  • This patient also had dilated IVC, Hepatic veins that  lead to clinical ascites.

Here , RV functional assessment becomes vital , but it is difficult many times. A simple clue is , as  the RV is able to generate 88mmhg pressure it implies ,   the   contractility  should be near normal .

RV EF %,  RV Dp/Dt , Tricuspid annular motion by  tissue Doppler are additional measures. Cine MRI can be a useful investigation prior to intervention.

Final message

  • VPS is a common acyanotic disease. Most are benign  and  milder  forms are the rule.
  • Dysplastic valves preclude balloon valvotomy. (In late stages   little  difference between dysplastic / non dysplastic VPS is noted  )
  • Severe progressive VPS  , like in this patient needs immediate balloon dilatation or surgery.
  • Long term outcome  is excellent except in advances cases where irreversible RV dysfunction sets in.

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An ostium primum ASD + Inlet VSD = AV canal defect !

Posted in cardiology -congenital heart disease, Uncategorized, tagged , , , , , on November 4, 2010| Leave a Comment »

A classical echo of  a common AV canal .

 

Note  the free floating common AV leaflet

An ASD

A  VSD

With all chambers interconnected it is a free for all circulation . The blood  seems to get mixed at the level of common AV orifice . Even though one expects severe cyanosis in common AV canal , the intensity of which is primarily determined

Common AV canal with free for all shunting . http://www.drsvenkatesan.com

 

the net blood flow to lungs which is dictated by  the pulmonary vascular resistance or the RVOT obstruction. This patient had no RVOT obstruction   but had  severe  pulmonary arterial hypertension.  In spite of raised PVR ,  some amount of volume over load of lungs  occur.

How to assess the  operability ?

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All that do not glitter . . . Bare metal stents pip Gold coated stents convincingly!

Posted in Uncategorized, tagged , , , , , , , on November 4, 2010| Leave a Comment »

Ever since coronary stents were introduced   metal market is having a  good time within human coronary arteries.The search  for the the elusive , ideal metal is still on   . . .  Nickel , stainless steel  , platinum  etc .

Some body thought , why not gold ?

For long ,  gold is known to be a good bio -compatible metal .

Two Gold stents were tried  .

  • Inflow dynamics  – AG Germany
  • Boston scientific –  NIR stent

Surprisingly , both showed   increased reactivity  with  coronary endothlium . The verdict  was  clear . Gold coated stent  was not good enough.

http://circ.ahajournals.org/cgi/content/abstract/101/21/2478?ijkey=f03f3c40dc4c5b2673d783f91c19f5ea685ed514&keytype2=tf_ipsecsha

Gold allergy

http://onlinelibrary.wiley.com/doi/10.1111/j.0105-1873.2005.00522.x/abstract

Final message

With the advent of DES ,  gold coating of stents lost it’s popularity  .Unless  new innovations happen in gold metallurgy , the  future looks bleak  for this precious metal  , at-least  in  the human coronary arteries.

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