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Archive for October, 2008

Why is criticism of newer scientific technologies always frowned upon or rather considered indecent ?

In science you don’t require politeness ,  we only  require correctness.This is especially true in medical sciences. But this is easier said than  practiced in the scientific community . In any scientific conferences the only a couple of minutes or few lines are allotted for the customary negative issues and  the limitations of the study.

Unscrutinised science can no longer be called as science !  it can only be termed as pseudo science!

It is believed skepticism is a powerful  dampener for the scientific growth.May be it was true in the earlier era of pre industrial world. But those days science was growing only with passion for discovery  and  an un contaminated mind.But now too many conflicts have cropped in.

 What is positive thinking ? and What is negative thinking in science ?

To be continued . . .

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What is herd behavior ?

It is a behavioral pattern where in animals and humans in large numbers , tend to behave in the same way at the same time without application of mind .


Herd behavior in human societies

Herd behaviour describes how individuals in a group can act together without planned direction. The term pertains to the behaviour of animals in herds, flocks, and schools, and to human conduct during activities such as stock market bubbles and crashes, street demonstrations, sporting events, episodes of mob violence and even everyday decision making, judgement and opinion forming. This is very much applicable to medical profession also.(Ref:Wikipedia)

Herd behaviour in animals and human how they are different ?

“surprise ! surprise ! There is  very little difference  noted , according to Hamilton”

A group of animals fleeing a predator shows the nature of herd behavior. In the often cited article “Geometry For The Selfish Herd,” evolutionary biologist W. D. Hamilton said each individual group member reduces the danger to itself by moving as close as possible to the center of the fleeing group. Thus the herd appears to act as a unit in moving together, but its function emerges from the uncoordinated behavior of self-seeking individuals.

Among humans for example when panicked individuals confined to a room with two equal and equidistant exits, a majority will favor one exit while the minority will favor the other.

Medical professionals as a herd


The practicing habits of  medical professionals  move , symmetrically as a herd . When a top journal or a opinion leader utters something every one tend to move in that direction .

If a herd leader says a particular treatment is great, every one will say yes . If he says nay every one will say nay !

No one will really question the direction they move ? Unless the correction occurs from within the herd. No external forces usually are effective.Herding is also benefitial many times as rapid propogation of scientific facts needs such behavior ,but it needs constant scrutiny.

 

Herd behavior example 1 : The most  typical example is the drug prescribing pattern of anti hypertensive agents over the past half century.The movement  from diuretics to beta blocker , from beta blockers to calcium blockers and to ACE inhibitor and again to diuretic  , then to ARBs and currently shying strongly away from beta blockers, in between  have a brief encounter with alpha blockers and finally  back to diuretics.

If a  particular physician by his insight , had clinged onto  diuretics ( Away from the herd ) for over three decades he is a real exemption , although branded old timed  and unscientific , he has been the most scientific medical professional indeed !

Herd mentality example 2 : Every one says so !  so it must be true ! Hormone replacement therapy good or bad goes with the leader of the herd . 

Herd mentality example 3: Very few cardiologists will be ready to agree the fact that , simple digoxin and diuretic ,ACEI, beta blocker,  administration could be as effective as  the costly cardiac resynchronisation therapy in atleast some of patients with wide QRS cardiac failure ( As we know up to 30 %  wide QRS CHF population do not respond to CRT) 

Defying Herd mentality resulted in major break throughs in medicine

               When every one was  saying beta blocker was harmful in CHF one person from Briton defied it ( Wagenstein, and now beta blockers are the mainstay in the management of CHF! )

There are hundreds of treatment modalities popularised by such herd behavior

Who is the watch dog  , whether science is moving in the correct direction ?


Read this land mark article  how medical research can be distorted by such learned behavior  and how scientific research should not be done .

Click on the image .

 This post is not intended to hurt anyone . It  reflects , human beings are not  fully evolved  yet , in the onging  process of evolutionary biology.

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                                          CRT , cardiac resynchronisation therapy  is being  projected  as a revolutionary treatment for cardiac failure , where a failing heart is rewired electrically through multiple leads and make it contract  more effectively.The success rate of CRT was highly variable.The basic question here  is,  there should be a  significant  documentation of desynchronisation  prior to CRT , for resynchronisation to be effective. Further , the sites of  myocardial  stimulation ( Coronary sinus/LV epicardial) , dose of electricity and the sequence of stimulation and the  electrical delay  are very  critical. Achieving this into perfection  is not a simple job and is  real rocket science ! ( If we can achieve 5 % of what  the normal purkinje network do within the LV we can term it a huge success.) Let us hope we catch up with nature . Finally , it is ironical  the sites of LV pacing ,  electrophysiologists  select currently  is infact not selected by them but pre selected by the patients coronary venous anatomy ! .So as on date ,  one can imagine how scientific this treatment could be !

                                         Initially it was adviced for patients with only wide qrs later for even normal qrs patients.When people started using it indiscriminately  insurance companies started to rethink and thus came the   RETHINQ study in NEJM  and brought a full stop to CRT in normal qrs CHF.

How to identify who will benefit from  the costly CRT  ?

It is a million dollar question. So millions of dollars were spent to identify the correct tool to identify the true responders to CRT.Echo cardiography with sophisticated methods tissue doppler, tissue tracking and , 3 D echo ,velocity vector imaging were done .These methods are not only costly but also time consuming and  hugely expertise driven.

Does all this  efforts with  advanced echo techniques worthwhile ?

This simple question was addressed in PROSPECT study in circulation

Click to read the article

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                                               The superior aspect of   coronary sinus and a portion of the left atrium share a common wall .Embryological defects in this area result in a communication between left atrium and coronary sinus. This defect  descriptively called as unroofed coronary sinus .This entity is most commonly associated with persistent left SVC. Extreme form of unroofing is some times termed as absent coronary sinus.

How to diagnose it ?

A high degree of anticipation is necessary in all patients with ASD or LSVC. A dilated coronary sinus in routine echocardiography warrants full investigation. A contrast echocardiography with agitated saline injection in left cubital vein will clinch the diagnosis as contrast enters LA after opacifying the dilated coronary sinus. During  right heart catheterisation catheter course entering coronary sinus and  advancing into LA through the fenestrations (Unroofing)  will confirm the defect.

How do you classify unroofed coronary sinus ?

The morphologic type of URCS was classified as Kirklin and Barratt-Boyes

 Type   I, completely unroofed with LSVC;

 Type II, completely unroofed without LSVC;

 Type III, partially unroofed midportion;

 Type IV, partially unroofed terminal portion

What is the clinical relevance of this entity ?

This entity should be suspected in every patient with persistent LSVC, ( and LSVC should be suspected in every patient with ASD). The hemodynamics is that of an ASD but if sufficient mixing of LSVC blood and LA blood takes place the child will have mild cyanosis.Some times when the coronary sinus is totally absent it will present as a typical dusky ASD picture which can closely mimic a TAPVC clinically.

Surgeons have a greater role in recognising and treating this entity. A typical repair will be done like this

 

Links to some of interesting articles on this topic

Raghib circulation 1965

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                                Acute coronary syndrome (ACS) is currently classified as STEMI and NSTEMI.This classification came into vogue  primarily to  triage patients for thrombolysis eligibility , as ST elevation is the  only criteria for thrombolysis.The  earlier term  non q MI  is largely used  to denote the  present day NSTEMI. In the past q  MI was referring to transmural MI non q MI  to non transmural  pathologically.(Of course , now we know  the relationship between q waves and transmurality is not good )

So when can we still use term non q MI ?

These terminologies of STEMI and NSTEMI are made on admission  at the emergency room.  ACS being a dynamic entity these  patients can  have rapidly changing  ST shifts , from depression to elevation and vice versa. Fresh T wave changes can also occur .Q waves  may or may not develop ,  depending upon the damage sustained to the myocardium and the efficacy of thrombolysis / PCI. So it should be emphasised here STEMI,  NSTEMI ,  q  MI ,  non q MI are the  descriptions of the  same group of patients in different time frames. The common mode of  evolution  of  STEMI  is  to q MI and NSTEMI  into non q MI. Cross overs can occur.

 

 

 The problem here is NSTEMI getting converted into STEMI  is quiet common and has no nomenclature issues . But  when   STEMI down grades  into NSTEMI  there is apparent  nomenclature incompatibility .This category of  patients have  no other labelling option other than “A STEMI evolving into non q MI”. Because one can’t label  STEMI  evolving into NSTEMI as  many of  them  will  have a residual ST elevation as well.

What is the final message ?

The term non q MI is still relevant and is used at discharge , in a patient with STEMI when he or she evolves without a q wave .In the setting of unstable angina , NSTEMI has largely replaced  the term  non q MI either on admission or at discharge.

Before I close

                 The important point to remember here  is NSTEMI getting converted into STEMI  is an adverse outcome and  in fact, it is  a complication and the patient should get an immediate  thrombolysis or PCI , while a STEMI getting converted into non Q MI is generally a  major therapeutic success.( Effective salvaging and preventing q waves )

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                Human civilisation has met so many challenges.Man kind has enjoyed the benefits of modern medicine for over a century.Now comes the new threat.Threat from within.The onslaught of marketing force has contaminated the medical science .

              It is widely  recognised  commerce is masquereading as science , from stem cell research to futile and costly  drugs, and  questionable  devices and procedures . 

How is the medical  community responding to this  issue ? 

Silence  is the response !  Why silent ? Are we the part of the problem ?  Occasional articles in the  Annals of medicine, Lancet, BMJ, or JAMA talk about these issues and nothing happens next .

Click below  to read one such article from the recent issue of Annals !

 

 

Let us hope the world financial crisis currently we are witnessing , would be good for human health as all futile market driven  , enforced medical expenditure goes bust !

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Non ST elevation Myocardial infarction  (NSTEMI) is a major mode of presentation of acute coronary syndrome.

Patients present with clinical unstable angina and  elevated cardiac enzymes or troponin.

ECG features can be any of the following.

1.ST depression (70-80%)

2.T wave inversion(10-20%)

3.Both ST depression and T wave inversion

4Post MI NSTEMI  -ECG changes variable ( Ironically ,even a residual  ST elevation may be present)

5.Normal ECG.

                                     Bulk of the NSTEMI belong to ST depression group.NSTEMI with purely T wave inversion is less common but occurs mainly in perioperative settings, pre existing CAD.NSTEMI with normal ECG is very rare  but can occur.

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