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A dramatic ICD shock . . . recorded live in soccer field !

October 25, 2013 by dr s venkatesan

This post , is  probably not meant for cardiology professionals.

Few technologies are clear winners in modern medicine. ICDs play  games  that would rival the God !

What is an ICD ?

Here is a man , who  drops almost dead by a fatal cardiac arrhythmia . In few seconds  ICD  machine recognises this arrhythmia ,charges itself and  fires a shock  of about 30 joules direct current .The arrhythmia is reverted and the fellow gets up as if  nothing has happened !

Watch this video

This revolutionary devices are  to be used judiciously in individuals with high risk  for dangerous cardiac arrhythmia.

The current  indications  as on 2012

Post MI  ( Only after  4O days*)
LV dysfunction EF ≤ 35%   NYHA  II or III  ( Please note , If  ≤ 30%, even Class I  NYHA can be implanted an ICD) *Why 40 days ?  Residual ischemic, Irritable  focus  should settle down
Myocardial disease
  • Nonischemic DCM  EF ≤ 35% with documented VT
  • Rarely other structural heart disease with recurrent risk for VT ( Few HCMs)
Primary electrical disease
  • Survivors of cardiac arrest due to VF without any completely reversible causes (Includes Brugada )
  • Malignant forms of syncope  with   idiopathic recurrent VT /VF
  • Congenital Long QT syndromes not amenable to beta blockers

Reference

Guidelines ICD pacemaker 2012 ACC AHA

Posted in Cardiology - Electrophysiology -Pacemaker, Cardiology -Interesting videos, Cardiology -Pacemakers and ICD | Tagged , , , | Leave a Comment »

Is Troponin positive unstable angina same as NSTEMI ?

October 22, 2013 by dr s venkatesan

This question always creeps in any coronary care unit.

Often times , there is a significant  histo-pathological overlap between severe degrees of  Ischemia* and  myocyte necrosis . (What is called micro infarcts, lacunar infarcts,  make us over diagnose MI). It is not yet clear , whether leaky myocyte cell membrane can release free cytoplasmic enzymes without actual cell necrosis.
Clinical Implication
Fortunately , there is not much .These bio markers are primarily used as prognostication tools .Many of these patients  need to  undergo early revascularisation. However , It is unwise ,to get alarmed by  just  Troponin positivity  in an other wise comfortable ACS patient.
* Some call severe degrees of Ischemia as Injury ! It is an old thought based entirely on ECG  .There is no specific cellular equivalent of electrical injury current !

Posted in Cardiac biomarkers, Cardiology - Electrophysiology -Pacemaker, cardiology -ECG, Infrequently asked questions in cardiology (iFAQs), NSTEMI | Tagged , , , , | Leave a Comment »

An Idiot’s approach to evidence based cardiology !

October 20, 2013 by dr s venkatesan

The current  fad called EBM has lots of lacunae. Though evidence based approach is  considered  the ultimate  journey  towards  truth  ,lot of non academic factors contaminate it .In it’s  current form , it is difficult to comprehend it.

This is an attempt to decode the mystery of EBM  expressed in a simplified  lay person’s term .They are the ones  from whom we learn  medicine. They are our teachers in the true sense.

evidence based cardiology guidelines evidecne levelBy the way ,it  is also my approach  to   EBM .Sorry , if  this post  sounds  arrogant ! It is not the intention .Truths often times appear brutal .

And   . . . the  Genius  approach to EBM  for comparison

 

2011_AHA_Classification

 

 

 

Posted in bio ethics, cardiology journal club, Cardiology quotes | Tagged , , , , , | Leave a Comment »

This ECG troubled us for a while !

October 20, 2013 by dr s venkatesan

In one of my classes , this ECG  was presented .  Controversy  erupted.It was about the  basics .

What is the QRS axis  of this ECG  ?

ecg north west qrs axis indeterminate

Not surprisingly there were  handful of answers .

  1. North west Axis
  2. Indeterminate QRS
  3. +150
  4. +180
  5. 0 degrees
  6. Extreme Right axis

Which is correct ? My guess  is ,  it should be  closer  to + 180 .  Lead 2 is equiphasic and perpendicular lead is negative limb of AVL ie + 150 .If you  plot Lead 1 and  AVF in graph and calculate  we get + 135 . (In the strict sense , we are not  supposed to take one standard lead and an augmented lead for plotting ). Finally, the strongest argument was ,  since  AVR shows  only positive forces  it  would make  north west axis more likely .

ecg qrs axis north west indeterminate

Causes of North west  QRS axis

  1. Denova North west axis
  2. Extreme Left becoming NWA*
  3. Extreme Right  becoming NWA

*Left becoming NWA is much more common than other types.

Chamber enlargement alone is not sufficient to shift the axis to NW corridor. There must be anatomical distortion of  his bundle and it’s branches to shift the axis dramatically .This usually occur in complex congenital heart disease. In acquired heart disease the  an apical VT is probably  an important cause for NWA.

One word about indeterminate qrs axis .

By the way , Indeterminate QRS axis  is not synonymous with north west axis. This term should ideally be used  if qrs complex is equiphasic  in all limb leads , when  qrs  axis  can not be truly determined .This situation commonly occurs when we encounter very very low voltage qrs  as in cardiac tamponade and severe hypothyroidism , constrictive pericardits, etc

If  the QRS is in north west  corrodor , How  to differentiate ,  whether it came from  extreme left axis  or  right axis ?

I am yet to find a correct answer for this.

  1. Pre-cardial pattern will help.
  2. A  q in V5/V6 would suggest  extreme left axis.
  3. May be we have to look the initial qrs vector in AVR lead for more clues

Traditionally , we talk about net qrs axis . We should realise net qrs axis is a combination of initial and late vectors .It can be dramatically different in different leads . QRS axis is  a two dimensional representation of three or more  (omni) dimensional electrical forces .That is the source for confusion. So,  do not unduly worry about the complexity .Blame it on the limitations of surface ECG !

Expecting some comments .

Posted in cardiology -ECG, Infrequently asked questions in cardiology (iFAQs) | Tagged , , , | 1 Comment »

A stunning breakthrough in permanent pacemaker technology !

October 18, 2013 by dr s venkatesan

Few Innovations are real breakthroughs in cardiology . Here is an imminent technology waiting to explode in the  permanent pacing . Expected to hit market next year (2014 in Europe ) FDA approves clinical studies .

nanastim

Click over for the animation video  of the procedure .

  • The wireless pacemaker has many advantages. (It’s devoid of all those pocket and wire related issues.)
  • The ability to change batteries is  a  going to be a  new paradigm shift in the filed of electro physiology. .
  • Down side would be,  right now it can be only VVI pacing . All that hype about    physiological pacing  will go to the background !

Future directions in Permanent pacing.

The only threat for this technology is the  concept of biological pacemaker Converting ordinary myocytes into  pacing cells by genetic engineering.This is expected to happen within few decades.

biological pacemaker

Posted in Cardiology - Electrophysiology -Pacemaker, Cardiology -Emerging technology, cardiology innovation, Cardiology Innovations, cardiology journal club, Cardiology-Land mark studies, Future cardiology gadgets | Tagged , , , , | Leave a Comment »

Calibrated PTCA guidewires : A simple Innovation can make cardiologist life lot easier !

October 13, 2013 by dr s venkatesan

It is estimated nearly half a  million PCIs are done all over the globe every year .Evaluating diagnostic angiogram is a critical  vital step, but  often times it is given less time and left to fellows .This is done mostly offline by Image  processing software. Curiously , lesion assessment  becomes a causality to the   visual acuity .It ends up  with lot  of whims , intuition and bloated egos of senior cardiologists !

Technical issues

The fundamental flaw in the  lesion assessment is ,there is  a dissociation in choosing the  “best view”  for lesion morphology  and  length  . Size need not be well  assessed in  the same view as morphology . For example , LAD is fore shortened  in LAO caudal view  ,  length measurement would be  erroneous  ,  still morphology may be well delineated .(Vice versa in RAO caudal view )

PTCA guidewire calibratedcalibrated ptca guidewire

Other source of errors

Reference catheter may be far  away in the Aorta , and confer a  magnification error . This becomes important especially in ostial lesions and associated  major branch lesions. The computer uses the edge detection algorithm  which carries an   inherent error .

Advantage of guide wire as a scale

  • Instant online measurement
  • Always on . Repeatedly used in multiple views .
  • You can’t ask for more accuracy .The scale is within the coronary artery  hugging the lesion
  • The end on view is effectively nullified .
  • Magnification  factor do not operate.
  • Finally , and most importantly in complex  tortuous , tandem lesions few mm errors can be disastrous .These calibrated guide wires will make our life lot easier.

Final message

Measuring  a coronary lesion remains a delicate issue . If only we have radio opaque  rings every 1mm or so in the distal end of the guide wire , we can measure the lesion  instantly and most accurately.

This will  definitely make our life  not only simple but help our patients with accurate stent sizing and avoid costly geographical miss (or inappropriately  long stent  that increase  metal load .)

After thought

I do not know whether  any of the existing  guide wires have this facility .(I guess it is not   . . .then , let this idea  be patented in my name !)  After all , It is a mean  task for all those mighty coronary hardware companies to add  few radio opaque rings to all  PTCA guide wires!

Medtronic, Abbot, Boston  are you listening ?

And . . . your opinion please !

 

Posted in Cardiology -Interventional -PCI, carotid interventions | Tagged , , , | Leave a Comment »

Unusual tips in PTMC : How to cross a critically narrowed mitral orifice ?

October 12, 2013 by dr s venkatesan

Click over the Image  for animation

ptca balloon for PTMC inoue 002

Posted in Cardiology - Animations, Cardiology -Non coronary Interventions -PTMC, cath lab tips and tricks, PTMC -Tips and tricks | Tagged , , , , , , , , , | Leave a Comment »

Why we take LV end-systolic diameter(LVESD) in mitral regurgitation assesement ?

October 11, 2013 by dr s venkatesan

Regurgitant  lesions of cardiac valves  are often tricky for the heart . Myocardium shows “love- hate” relationship with these  leaky valves.  Some of them are  “sort of”  stress relievers for  LV . A mild MR will make the LV comfortable in terms of wall stress. When the wall stress is reduced the contractility increases and LV EF may raise a little.Hence EF is never going to help us to assess true LV function in MR .

LV end diastolic dimension(LVEDD) is  a preload dependent  parameter .A patient with 6.5cm LV EDD  may still  have good contractility  and he may reach even a  40mm LV ESD, implying an intact LV function.

LV function should be best  assessed  in systole .(After all ,  systole is the prime function of heart) .Further , it should be assessed when the LV is  free from  influence of the all  loading  conditions of heart .  (Note : The initial part of systole  depends on after load. As the systole progresses the influence  of after-load lessens .In the pressure volume loop* , the point at which loading conditions are least operative is end systole.)

* Please realise , heart is a dynamic organ there is no true load independent point in cardiac cycle  as pressure and volume are eternally coupled.

What happens in AR ?

The same rule applies for Aortic regurgitation, but the parameters worsen little later than that of MR. For same degree of regurgitant fraction MR will require early surgery than AR.The reason for better  tolerablity of  AR  is due to largely  intact LA function and compliance till very late stages of AR.(In AR- it’s single chamber volume overload , while in MR  it’s two chambers !)

Final message

LVEDD is not used in assessing MR  as it is a pre-load dependent parameter that will not reflect true myocardial  function /dysfunction. LV ESD is fairly accurate  measure of LV systolic function minus all loading factors .

Watch out  for next topic

Vasodilator therapy in MR and AR : How is it different ?

Posted in Cardiology -unresolved questions, Infrequently asked questions in cardiology (iFAQs), Mitral regurgitation, rheumatic heart disease, valvular heart disease | Tagged , , , , , | Leave a Comment »

Future directions in cardiology : A land mark review by Valentine Fuster

October 4, 2013 by dr s venkatesan

Medical research   often ventures into a directionless and meaningless  exercise with or without intention .The reason is simple , unlike  other fields,  scientists enjoy  the ultimate freedom of expression.

How to find genuine treasures from this chaos ?

We need people like Valentine Fuster ,

valentine fuster global cardiology what is the future

Here is link to the article in   circulation 2011  which I consider a must read for all cardiologists !

global cardiovascular health valentine fuster circulation 2011

Posted in cardiology journals, Cardiology research topics, Cardiology Risk assesment, Great Men in cardiology, Great websites in cardiology, history of cardiology, Land mark articles in cardiology, Top ten in cardiology | Tagged , , , , , , , | Leave a Comment »

What do you mean by adequate LV function . . .Doctor ? !

October 1, 2013 by dr s venkatesan

Many modern  day cardiologists  consider  doing echo ,  a mean job and leave it to  technicians and fellows . Final report  often ends up with a cursory glance. The culture of reporting an  important aspect of LV  function is reaching a new low. It is common  to find the following terminologies  in  the  echo reports in many  parts of the country*     (Guess it is not used elsewhere ! )

  • LV function good
  • LV function adequate
  • Good bi-ventricular  function
  • LV function fair

what is adequate LV function

Among these , the term adequate LV function has caught  the  imagination  of young cardiologists ! Especially , this description  often appear in pre- operative  screening echo for non cardiac surgeries .

Recently ,one of my patient asked me what do we mean by adequate  LV function . I told  him it means nothing . . . it’s all  fancy words  !  but , generally  it is used to imply  normal LV function . . . I  clarified .

Think over for few minutes   . . . what do we  want to convey  by calling LV function  as adequate ?

Does it mean normal ?  or  Just less than normal  ?

If adequate LV function  is accepted ,  what is inadequate ?

Adequate for whom ?  For the patient ?  or  for the physician ?

Adequate  for daily activity  ?  or  Adequate to  with-stand  the proposed  surgery ?

Final message

Even  learned cardiologists indulge in this  term  frequently . This is  rather a fancy and unprofessional  way reporting LV function . They pass this  style to their residents  as well para medics .Adjectives  in medical science are not banished . . . but should be   judiciously used . In my opinion  the term adequate LV function should be removed from all echo labs .   Youngsters please  watch out.

Related links in this site .

LV ejection fraction fallacies

What is LV dysfunction ?

Posted in Cardiology -unresolved questions, echocardiography, LV function | Tagged , , | Leave a Comment »

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