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Archive for April, 2010

Wide qrs tachycardia often  evoke a   OCD like reaction  among  many  cardiologists (Obsessive compulsive disorder).  Whenever we are given a strip of wide qrs tachycardia  we are compelled to initiate a  conscious or  subconscious debate , whether it is VT  or SVT . Tens of thousands of articles, seminars, CMEs , have been conducted for over 30 years  for  decoding  wide qrs tachycardias  . The fact that the confusion  is still widely prevalent indicate only two things

  1. Either , it is not possible to arrive at a simple fool proof  bed side modality  to confirm either VT or SVT
  2. Or it is a too trivial  electrophysiological   issue  that   need  not be worried about  as we have broad spectrum antiarrhythmics (Like antibiotics ! , where we  rarely  bother about identity of the culprit  bacteria  )

The power of statistics and commonsense have never been applied  in the management this vital cardiac entity  .While a  75% sensitive  exercise  stress test (EST) has a huge following in clinical cardiology , a   99 % sensitive   clinical criteria*  for diagnosing VT is  not respected .

*All wide QRS  tachycardia  in patients with   with history of   CAD/STEMI would be VT

If only we had applied our mind to this article published in 1988 we will never ever have the need to split our hairs for decades.(That too without success !)

In  pursuit of  knowledge , are we often  chasing  an imaginary  issue ?

The cardinal  principle of medicine says

“Diagnosis should precede treatment  whenever possible

But there need to be a correction  in the above statement .  Time , effort , cost involved in arriving at a  diagnosis  should be meaningful .( Needless to say  . . . it should  a correct diagnosis  too ) And if the power of statistics far exceeds the  frivolous scientific data  , street sense can be applied  liberally even though current generation may call it un scientific .

The issue here is  not being  scientific or unscientific , but whether you are right or wrong  . The article  which is quoted here  has a great insight  about the philosophy of VT diagnosis.

The message form this article goes something like this . . .

In the diagnosis of  wide qrs tachycardia , If we apply  the so called scientific principles   the chances  for missing   a real VT is extraordinarily high , while  if you blindly apply common sense and logic you are going to be 90% right .

What a powerful  statement this !  even though it appears  absurd ,  it is absolutely true !

A young physician  should realize the importance of this . Scientific  decoding of arrhythmia  may be an academic  pursuit but in a given patient at bedside  diagnosing by experience and common  logic are  far more productive and accurate. Miss diagnosis of VT was not common prior to 1980s .  It has become a recent phenomenon .

Probably too much of electrophysiology haS  made a simple diagnostic pathway a complex one. When we relied only on commonsense the errors were less . I  have  often observed  fellows  making mistakes quite frequently  while  nurses  were too confident  to call a wide qrs tachycardia   as VT .

Final message

Medical decision making is an art , in fact it is  a “fine art ”   We keep saying this for centuries , still medicine as a  science  easily overtakes medicine as an art. Here comes the problem . Some times (or is it many times ! ) too much of inquisitiveness in the   name of  science  make practice of medicine  complicated and the victims are often the patients !

Let us simplify medicine  . . . let us accept an occasional  bad outcome  . . . for not being 100 % scientific  ! After all  , a million mistakes happen every day in the  pure  scientific  pathway .

Reference

http://www.amjmed.com/article/0002-9343(88)90008-3/abstract

Also read Knowledge disease

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Like in neurological disease, one can locate the site of block in bundle branch blocks. Though it has never been thought ,  to be clinically important to localise a BBB . (Unlike coronary lesions)

Generally ,  RBBB can be proximal  or  distal peripheral type.The commonest site could be the distal  type.

It should be realised , for over 100 years in  electrocardiology , we have been using some inaccurate terminologies just because it is easy to understand or being traditional .It is difficult  to assimilate a fact , even today that   “An electrical delay in conduction and block are one and the same ”

In fact,  bulk  of  the RBBB is nothing but delayed conduction over this bundle. So whenever we say RBBB  , we imply an incomplete block  ie conduction still occurring   over the  so called blocked bundle.(This dogma applies for LBBB and AV blocks also to a lesser  extent)

Examples of delayed  RV /RVOT conduction

  • Any disease where  RVOT dilatation  occur can cause a RBBB
  • Atrial septal defect
  • Many cases of RVH
  • Pulmonary arterial hypertension

What is the benign rSr’ pattern in V1 ?

This is nothing but a relatively late depolarisation of  RV outflow or conus that produce a terminal RV activity .

Many of the ostium secundum ASD may show just this rSr’ pattern   confirming there is no organic damage to RBB in ASD .

Calling rSr’ pattern as incomplete RBBB is not advisable (As many ECG books may suggest ) .This is because , even full blown RBBB pattern may actually be an incomplete one .Further , the degree of terminal r’ in V1 or s in lead 1  does  not always   determine the completeness of RBBB.

Is there a totally blocked right bundle branch block ?

Yes , it is not common .

  • It can occur in extensive anterior MI .
  • Some cases of Ebstein anomaly.

It can be an working rule , complete RBBBs  locate the lesion proximally and incomplete  ones distally .

What is the other evidence for RBBB in ASD  is  only a simple   delay  in conduction ?

After ASD closure  in many of the patients the RBBB pattern may disappear.This indicate RVOT regression .

Can you clinically differentiate the proximal from  distal RBBB ?

Ironically ,what is difficult in ECG may some times be possible clinically.The classical description of wide splitting S2 occur often in peripheral RBBB.

It represents a delay in the closure of pulmonary valve due to delayed electrical activation or increased hangout interval as in ASD .Logically S1 should also be split in RBBB. But this is not often discussed.

This is because , the split in S1 is lesser in magnitude and is not influenced by the hangout interval .(Hang out interval is the time taken for the blood ejected from RV to fill the pulmonary circulation. Due to the low impedence of pulmonary circulation the the blood that is ejected into the MPA continue  to run off for about 100milli seconds even after the RV/PA pressure crossover .)

S1(T 1) occurs  immediately with the onset  of RV contraction . Similarly M1 occur with LV contraction.It should be recalled it requires hardly 5mmhg of RV pressure to close the tricuspid valve and about 10mmhg for LV to close the mitral valve.

If for some reason if  there is a delay  in RV contraction , as in very proximal RBBB the T1 is delayed and hence S 1 split.

Note in most of the peripheral or distal RBBB the bulk of the RV free wall contraction is not interfered with . So , in distal RBBB it is highly unlikely the S1 will be delayed or split while S2 will be delayed.

What happens to S2 in proximal RBBB ?

Logic would dictate both S1 and S2 should be wide split.

Final message

There is a simple way (Some would call this an futile  academic  excercise  !)to  differntiate proximal from distal RBBB.If the first heart sound is split wide , it fixes the lesion proximally. This may  indicate a more adverse outcome than a simple peripheral delay in conduction.

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Echocardiography is an imaging tool . Can it  be used as a non invasive  EP lab ?

Heart is an  electromechanical organ . For every mechanical activity there must be a electrical event preceding it . So, when we analyse the cardiac contraction and relaxation it indirectly provide us clues how the electrical activity spreads across the heart.

The concept of using echocardiography for diagnosing cardiac arrhythmias have never been popular for the simple reason we have a cheap and best modality : The ECG.  But, it  does not give us the temporal relationship with the cardiac contraction. When these two are combined it can be a really powerful tool to analyse many cardiac arrhythmia.

  • In fact ,  for every brady and tachyarrhythmia there has to be an unique pattern of IVS motion and mitral , tricuspid valve movement.
  • Almost all bradycadias can be diagnosed with echocardiogram by virtue of analysing the timing of  atrial vs  ventricular  contraction.
  • We know echocardiogaphy is the only modality available to diagnose fetal cadiac arrhythmias.* (How can  this modality becomes useless when the baby comes out of the mother’s womb  !)
  • Apart from this there is an  unique use for echocardiography to locate accessory pathway in WPW syndrome

The premature contraction of LV can be seen in few as  an early systolic dip in IVS movement -Type B WPW.

Image courtesy :  Helmut F. Kuecherer Circulation 1992;85:130-142

Abnormal jerky movement of LVPW indicate left accessory pathway -Type A WPW

Newer modes of echo like tissue doppler will improve the phase analysis of tissue motion and may provide us accurate information about preexcitation

Final message

The future looks bright . Time is not  far off . . .  where ,  we shall  use ultrasound as an adjunct  EP  study .

Reference

*Fetal Echo  =  to  Fetal electro cardiogram

WPW syndrome

http://circ.ahajournals.org/cgi/reprint/85/1/130.pdf

http://content.onlinejacc.org/cgi/content/full/33/3/782

http://www.heartjnl.com/cgi/content/full/82/6/731

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When every one is thinking bare metal stents are dead ,here comes  an ace  from Medtronic !

A breakthrough technology that make stent navigation into complex lesion as smooth as “knife in butter”

“If only you feel it ”  says the Medtronic ad

The smooth flowing metal inside the coronary artery

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Ego can be a  great  motivator and destroyer as well. It has the  potential not only  to damage the self  but also the people in the near domain .This has been proven in all walks of life. Medical practice is no different . In fact ,it can have the more devastating effect as the victims are often the poor patients.
The medical ego can be individualistic,  departmental, institutional, etc.

Often in the dormant  form , can raise to gargantuan  levels when stimulated or challenged.  In its mildest form it occurs every day in the office practice. A physician  often thinks he is always right and fails to get a second opinion even in difficult  cases . Some where  along  the medical  curriculum  ,  doctors have to be taught that ,  what we know is only a fraction of what we are supposed to know ,  and  the importance of self auditing. This never happens in most medical schools.

Individual Physician ego

This exist in several forms . Ego with fellow colleagues is the most common type . Failure to accept a error in diagnosis is the most  frequent form injured physician ego. There are many instances doctors carry on with the wrong diagnosis tag (On their patients)  even after some authentic documentation is available against it. This especially happens when the correct diagnosis is made by  a junior colleague . Eg : “I still think it is a pheochromocytoma let us do the scans again”  Same tests  are repeated . In the intervening period  involves  treatment delay  and  financial costs for the patient. It is obvious , such an  ego in emergency rooms can be  disastrous .

Few doctors have a habit of asking for fresh set of investigations even if the patient has recent records of his illness . This is because many  feel interpreting   investigations ordered by other doctors is an inferior job .(Of course ,  financial incentives for repeating the  tests  could also be a motivation  )
Ego with paramedics and fellows

This is also quiet common. Doctors expect  their orders to be carried out at any cost.  They take it very seriously , if a nurse or a junior doctor behaves independently . This is understandable as it raises the fundamental question  who the  boss is ? !  But ,  the problem here is, even a smart move in the interest of patient is  not always relished  the physicians . (Because it is  perceived as an  insult to the consultant ) . You can’t act smarter than me !

We know the major responsibility  of caring a patient lies with staff nurses and  junior doctors .(It is a universal medical rule the consultant will be remote from the patient care unless of course it is needed).If the specialist exerts an  academic ego on them , there is every chance for the patient to suffer as  even vital interventions could be delayed.

(Eg :   Sir , I withheld  the beta blocker in  this  patient  as he  had a  bradycardia ! I thought it is  better to remove the urinary catheter as the patient was struggling with it  etc and etc )

I have observed  , even  some of the shrewd  directives  from the residents and junior doctors have elicited  big hue and cry from some of the renowned physicians of our region.While many   recognise the good work done by the junior colleagues  , still  their  ego does not allow to  appreciate and complement them . This is not a good sign for the  medical professional .

Specialty ego and departmental ego

This is new phenomenon . Traditional ego was between surgeons and physicians. Now , with medicine growing leaps and bound there is probably a medical and surgical specialty for every human organ . This helps the physicians ,  to shrug of the collective responsibility . It  has become a  dangerous trend in many institutions.

God created  human body as a single entity  . Specialists  share their  organs  , convert a  human body  into a commodity (Has to  make a living out of it )  As the medical science is branching out at a phenomenal rate  it becomes   a difficult task for them  to come to the rescue of the patient when they need a collective intervention  . Further , conflicts of interest and ego clashes take a front stage.

Even in an  academically and ethically superior medical center it is a  herculean task to arrange   for . . .example
An ENT surgeon and neuro surgeon to operate a nasal tumor together.

A hybrid procedure of PTCA and CABG (Could be very useful in many situations)  can not be practiced  that easily .

The issue here  is not simply logistic .It goes beyond that . . .

(Why should I  sweat for some one else’s fame ?)

Institutional Ego

It has a peculiar issue .The  admitting  physician is  vested with supreme powers – he becomes  the sole caretaker  for the given  patient .Though it fixes responsibility , it has a potential  risk , as this  patient automatically  becomes untouchable for other consultants . There are centers in which even intra departmental  consultations are lacking .I know at least a handful of cardiologists who  do not talk with each other  even at times of crises in cath lab. This is more prevalent in fully commercial institutions .

In this regard  group practice with fixed financial remuneration may be a  lesser breeding ground for ego clashes.

Another form  egoism may be financial  discrimination , which  is seen in some of the big corporate hospitals . There are instances some doctors and institutions  shy away poor or relatively poor  patients .There are institutions which feel allowing entry to   less sophisticated public  inside  their premises is detrimental to their reputation and ambiance.  

Ego issues with patients.

Generally doctors show great respect for their patients. Information sharing is the major issue. What to tell and what not to,  can  some times reach really difficult proposition. Does the patient have a right to criticize the treatment ? Whether you like it or not some patients do it .

Few suffer from a  worst  form of physician ego , that is directed  against their own  patient. Doctors are  rarely  comfortable when patient ask probing questions.This is acceptable in few instances. The root of the problem is doctors rarely accept their ignorance .

There are many instances  where a consultant   refuses  to see  his own patient  once he  gets  a second opinion from another doctor . It need to be realised  this is actually the fundamental right of the patient he is executing .No need to get offended .

Why this ego ?

It is the  part of normal human psyche. There is no reason to believe doctors  are different . But the following could be unique factors .

  • A subconscious feel of  ” demi god” status  conferred  by the patients .
  • Failure to have an open mind approach .
  • This translates into fixed ideas about a patient and his illness.
  • This is especially common in countries  where , single doctor or a family of doctors run nursing homes .

The other substrates  for ego growth among physicians are

  • Academic  excellence
  • Practical skills
  • Popularity in the society
  • Financial superiority

Negative ego : A feel of inferiority also creeps in for many physicians  who  find to hard to acquire the above .And this  can  have  a serious effect on  the patients .It is  shocking to note many of  the academically incompetent  have a strong  dose of ego .This is most dangerous for the society.   A deadly combination of  incompetence  and arrogance

What is to be done ?

  • Containing  the  physician egoism  could be more important for doctors  than attending to  sophisticated CMEs and conferences and workshops .
  • Counseling is required for many .
  • Behavioral science with the specific tips for  self-regulation is to be included in the basic undergraduate medical curriculum
  • Courage to tell the truth to their patients to be imbibed.

Final message

Hippocrates said some 2000 years ago the fundamental quality of a doctor  is  to accept his limitations and ignorance .Every action of his or her, should aim  only at removing the suffering of the patient .

Now we are in the era where , market force  have literally hijacked the medical filed  . A  medical degree  can be bought in a weekend university shopping (At least in India it is possible ! )  .

In this scenario  if our students grow with one more wise  ie “hyped up ego”  one can imagine  where our profession is heading for !

We need to initiate a debate on the issue . And there need to be a movement to cleanse  the contaminated profession. It should be  in the league of nuclear  treaty ,  war on terror or the global environmental protection.

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It is well-known sexual arousal and activity is a powerful hemodynamic stress .In the healthy persons it is never an issue .In fact there is data to suggest sexually active men and women live longer.

But , in patients with cardiac risk factors or an established coronary event unrestricted  sex can be a risk factor for CAD.

There needs to be a distinction  between a coronary risk factor and a coronary  trigger .Trigger is an  immediate switch  for a coronary event in a  patient with  baseline risk profile .It is highly unlikely triggers alone can  cause an ACS .There need to be risky substrate.

Extra marital sex could be such a trigger in some .(Both male and female)

  • The sexual activity performed with guilt  has  more powerful risk.
  • First time offenders
  • New  partners
  • New environment

All of the above are  supposed to increase  the risk .

The mechanism  attributable is  a   sudden adrenergic  surge  which inappropriately high when compared to marital sex . In conservative societies , the effort taken to hide the illicit relationship   is much more stressful than the event itself. And hence these men and women carry on their new-found coronary risk for longer periods.

Reference

http://www.ncbi.nlm.nih.gov/pubmed/20382352

http://drwes.blogspot.com/2010/04/extramarital-affairs-and-heart.html

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Constrictive pericarditis(CP)  has been a fascinating disease   for the cardiologists  for many decades .  (Of course , not  so fascinating for  our  patients!) The reason why clinicians were thrilled to diagnose this entity is due to the unique clinical and echocardiographic and hemodynamic features. Further , it is  one of the few  curable forms of cardiac failure.
It is also about the  philosophy  , pericardium an inert  membrane  which is supposed to protect the heart , becomes a  villain  . When this innocuous layer  is insulted by  chronic   infection (Tuberculosis most common) , radiation injury or post cardiac surgery  it takes a dangerous avatar and  start invading   the organ which  it  guards .
The pericardium becomes thickened , (often > 5mm -2cm) calcified , behaves like a “shell of tortoise‘ and begin to constrict the heart . Once the process of constriction sets in it becomes relentless . It only   requires   , a 10 -15mmhg of constrictive  pressure to make  the poor heart  struggle to relax .(The maximum intracardiac  diastolic pressure ,12mmhg(LV)   .For the right side of the heart it is very low (0-5mmhg) .
So it is obvious the right side of the heart RA, RV gets compressed first .This is why the classical features of constriction with edema , ascites elevated JVP occur.The associated hepatomegaly some times mimic a chronic liver disease.  Of course  relying only  on the  classical findings to diagnose CP would be a crime now .
There are many atypical varieties of CP
  • Localised constriction
  • LV>RV constriction
  • RV>LV constriction
  • Transient constriction
  • Effusive constrictive

* Rarely  constriction is confined to AV groove .  This article  is about this entity.

It is difficult to imagine how a pericardium constrict a rigid fibrous skeleton of the heart namely the AV groove.
But what happens is ,  there  are some gaps in the ring  . The  posterior mitral annulus which  has a deficient  rim  and forms  the most vulnerable  zone for pericardial constriction
Further , AV groove  is located  in a relatively  gravity dependant portion  of the heart  . It facilitates  stasis of inflammatory exudate  in this groove .This may be  the reason  why the  AV groove  shows high incidence of   calcification.
Clinical features of AV groove constriction
It mimics  a presentation of valvular heart disease.
A mid diastolic murmur across mitral valve may occur mimicking valvular MS.
Synonym : Mounsey’s pericarditis
This type of pericarditis should ideally  be called as Mounsey’s constrictive pericarditis   for his
elegant description of this entity 5o yearts ago  even before    Echocardiography was invented.
(These are the days , we struggle to diagnose Mitral stenosis without echo is a different story !)

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