Posts Tagged ‘circulation’

We presume  ECG  fails miserably against echocardiography for assessing hemodynamics , while  echocardiogram  has  little value  when it comes to studying   electrophysiology .  Ironically ,  we often  ignore  the fact  ,   ECG can  provide  important long-term   hemodynamic  data . The pattern of  chamber enlargement  give us  vital clues to the prevailing hemodynamic  stress and loading conditions. While echo  can be termed as an  anatomical and  physiologic   modality  , ECG  apart from  its unique capacity to record cardiac  electrical finger prints ,  it  provides  useful ,  anatomical ,  hemodynamic information too !

While Doppler is a  fascinating modality to measure hemodynamic data in a moment to moment fashion it can never ever tell us  , what has been going around in the preceding months or years. This  is were chamber size helps which  give us chronic physiological information (Chronic  Doppler ?)

A simple E:A reversal  in  mitral inflow doppler can be a  innocuous  finding in isolation  . If it is associated with even   minimal grades of  LAE  it gains huge importance. That is why left atrial size is  funnily referred to as HB A1C of diastolic dysfunction ( A marker of chronicity  of  diastolic dysfunction)

If LAE is so important to diagnose diastolic dysfunction , why  we are so  obsessed  with doppler filling profiles  of mitral valve ,pulmonary veins, mitral annular tissue Doppler and what not ! .Many of these sophisticated doppler methods are extremely operator dependent  and are  subjected  to technical and mathematical errors. Especially , with  tissue doppler where we  magnify the errors as we  filter  extremely  slow tissue motion .

For  many  decades  we  have failed  to impress ourselves  , about the importance of subtle P wave abnormalities in the  ECGs   of  hypertensive patients.

In fact those  innocuous looking  slurs and notches   in P waves ,  suggest the left atrial  stress and a definite marker of underlying LV diastolic dysfunction .

P wave is the only electrical wave that occur in diastole .Hence there is no surprise  ,i  gives us enormous information about this phase of cardiac cycle .

If only we look  at them carefully, zoom it (Now it is made easy with so many softwares)  analyse critically we can find a wealth of information about the atrial behavior in hypertension.

Experience from our hypertension clinic  with periodic echocardiograms suggest ,  the following  ECG  findings   can be   good markers  of significant  diastolic dysfunction .

  1. Notched P wave
  2. Wide  P waves
  3. Slurred  P wave
  4. Bi-phasic P waves

* Surprisingly  , these abnormalities correlated with at least grade 1 diastolic dysfunction even in the absence of  for LAE or LVH by echocardiogram.

** In an  occasional patient  P waves  can widen due to inter atrial block or conduction delay. This a rare exception for wide P waves without LAE.

Final message

A well recorded and   analysed   ECG can  predict diastolic dysfunction  with fair  degree of accuracy .This fact need to be emphasized  by every one  .  Next to ECG ,  LA size and volume  by 2d echo are excellent parameters  to assess diastolic function in a long term fashion. Sophisticated  but  error prone ,  momentary doppler parameters are getting too much attention  at the cost of simple ,  shrewd ECG and 2D echo  !

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  • It is a complex PCI procedure meant for  high risk  bifurcation /Trifurcation lesions
  • Two stents are simultaneously  deployed.
  • It aims to prevent sudden acute occlusion of one of the major  branches .
  • It is not an easy procedure , and be used only in rare circumstances .
  • Distal left main and ostio proximal LAD/LCX  is a  classical  example.
  • Navigation can be difficult , only well experienced operators should attempt it.

*Is there a ready made two lumen stent available ?

The image is meant for concept purpose only !


It is one of the techniques available to stent unprotected left main

An excellent review  in  ACC intervention journal for unprotected left main .

Click on the Image to reach the article


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micro circulation shockHuman circulatory system consists  of  the heart , the arterial  and the venous  systems . Together they constitute the  three important limbs of circulatory system namely , the  pumping, delivering and retrieval systems .In physiological conditions approximately 6 liters of  blood  has to traverse  the entire   circuit every minute . The  purpose of the  circulatory system is not simply circulating the blood within the body,  but  it has to perfuse different vital organs like brain, kidney, liver . Of course ,   the heart has to self perfuse the coronaries  by it’s own contraction.The organ perfusion is determined by local and systemic  regulatory mechanism. A gamut of intrinsic and extrinsic neuro humoral modulators take up this job. A functionally intact autonomic nervous system is an absolute necessity to maintain tissue perfusion.  The perfusion pressure is highly variable in different organs and different cells. Similarly the ability to with stand ischemia and hypoxia also varies. Shock  is a general term used to imply ,  circulation is seriously compromised.Here we will confine our self  to the intricacies of peripheral circulatory shock

Traditionally shock is  classified as

  1. Cardiogenic shock
  2. Hypovolemic shock
  3. Vasodilatory /Redistributive/Septic /Warm shock (Can be called  as  arterial shock )

The hemodynamics of the first two are straight forward and easily understood. In  cardiogenic shock , the pumping action of heart is primarily affected .In hypovolemic shock  there is no  structural defect in any of the   circulatory limbs but there is  a loading defect due to low blood  volume as in hemorhagic shock .

The term vasodilatory shock or redistributive shock is most poorly understood and most difficult to treat.

The  concept is further confounded as  combinations of   above three mechanism in a same a pateint can occur . ( More commoner than we believe !) . An example could be a septic patient  with an  internal bleed and myocardial  depression either due to preexisting LV dysfunction or circulating toxins.

Since  we have always perceived heart as  the  sole  vital  component of circulatory   system , our understanding of the role of the vascular tree which is primarily responsible for delivering the blood is largely undermined and neglected. We are always happy if the EF %  is normal.

Classical features of  circulatory failure ?

The cardiac contraction is good.This is documented by normally contracting LV by echocardiography. The pulmonary capillary wedge pressure is normal (<12mmhg).Still the patient is in  hypotension with  evidence for vital organ under perfusion like oliguria and reduced mentation.

What is vascular tone ? What sustains  the flow of blood into the tissues  ?

The entire  vascular tree could form a   few 100 kilometer length.(Capillary /arterioles /venules included). While , it is easy to  percieve heart as  a dynamic pumping organ ,  it is a less recognised fact the entire vascular tree is also  pulsating  to every beat. That is the rhythm of life. What makes the vascular tree to pulsate ? Apart from  contraction of the heart  , there is an  intrinsic tone for the large , small arteries and the arterioles and veins  .This tone is vital for pushing the bllood into various organs and return into venous circulation and subsequently back into the heart.

microcirculation shock cardiogenic septic

The  millions of perivascular cuffings and the artreriolar smooth muscles  can be considered as  small micro pumping stations situated along side every cell.

It is very important to emphasize here,   if  tone in these microcirculation is less than optimal , the patient’s circulatory  system can never complete the desired circuit  even if the heart has 75% EF . This exactly is happening in circulatory shock . The vascular tree fails to accept and return the pumped blood  in timely fashion.

What controls this tone ?

It is chiefly under the control of autonomic nervous system.The endogenous vasoconstrictors , the adrenergic nervous system, the endothelins , the angoitensins constrict the vascular smmoth muscles while endothelial relaxing factors ,( EDRF -nitric oxide relaxes it ). There is a delicate balance between these forces.

A cardiovascular health of a person is not simply having a healthy heart , he has to have a healthy vascular system with intact biological activity.The fact that , not every one with sepsis react with poor vascular tone indicate inherent capacity to neutralise toxic vasodilatory neuro transmitters.

Is there a invisible parameter called vascular ejection fraction  in circulatory  system?

Yes. It must be . We rarely discuss it . The vascular tree has an important role for pumping the blood into the tissues.  It needs micro manometers to assess the systolic and diastolic dimensions of small arteries and arterioles . But  what  we know is ,  it is grossly impaired in circulatory failure.The vessels especially the arteriolar smooth muscles which determine the perfusion pressure of cells go into state of permanent relaxation. The vascular smooth muscles lose control from autonomic innervation and become flabby. It is the   DCM equivalent for blood vessels. The arterioles no longer regulate blood flow and fluids get sequestrated in various viscera,( often called thrid spaces) and organ dysfucntion sets in. The resultant hypoxia aggarvates the tissue stagnation by producing still unnamed vasodialtory mediators.

What are the pharmocological approches to increase the vascular tone of a failing vascular tree ?

It is a very difficult problem even in this modern era of vascular medcine. Once set in ,  these patients invariably go downhill .The primary underlying problem  ,  often sepsis  need to be corrected. Usually these  patients need multi organ support.Vasoconstrictors like epinephrine,nor epinephrine , dopamine  can sustain vasoconstriction temporarily . As we know the vascualr smooth msucles can not be kept on this assited contrection mode for long.It is bound to fail .Patients native autonomic function has to recover fast to wean of this support.

What is normal circualtorty time .How is it altered in circualtory failure  ?

The normal circualtory time is 15-20 seconds.It is many times prolonged in circualtory failure inspite of the cardiac contraction being normal

What is effective circulatory volume ?

The body fluid compartment is divided into ICF,ECF & interstitial  spaces.At a given time , the fluid in the extracellular space  can only  take  part  in circulation. A good blood pressure does not always mean a good tissue perusion why ? This is very important to realise as blood pool has to dynamically exchange with intra cellullar compartment. At times of shock the blood can bye- pass the cells through the alternate circuits in the periphery of micro circulation. So what is circulating in the system may not be taking part in tissue perfusion .This is the concept of  effective circulatory volume.This is especially noted in hepatic shocks and in some terminally ill malignancy.

Is there a venous shock syndrome ?

Cardiologists  often show a  step motherly  attitude to venous disorders. In fact many  of the   cardiovascular  specialists   think their   job is  taking care of  heart ( Of course , a little bit of aorta and venacava !) .It is surprising  to know,  there is little  scientific data on determinants  venular and venous tone (Both small and large veins).

The power of venous system should not be under estimated  as it pumps  many litres of blood every minute  defying gravity ! For this to happen it needs a vigorous tone .Where do it get from ?  : The same  autonomic nervous system that controls the heart. Remember , in pathological states there is a  great chance for this to go out of control. So venous shock is a clinically distinct possibility. In fact inappropriate administration of nitrates which reduces the venous tone has resulted in many adverse events in RV shock.

In a patient with circulatory shock , we would  never know  how much is contributed by venous side and how much by arterial side .This is important as in circulatory shock we administer all vital drugs through veins.Now it is thought  systemic venous  dysfunction also contribute to shock state.

Clinical situations of circulatory failure or shock

Bacterial shocks

  • Gram negative sepsis
  • Staphylococcal shock

Viral shocks

Dengue/Swine flu etc


  • Dissiminated intravascular coagulation
  • ARDShypoxic shock
  • Elderly,Diabetic  autonomic neuropathy
  • Persistent post operative hypotension due to silent autonomic neuropathy.
  • Some cases of Spinal shock
  • Toxins – Scorpion etc(Intense vasoconstrictive shock )
  • Terminal shock in liver failure/Hepato pulmonary   syndrome

* Idiopathic unexplained persistent hypotension , with difficulty to wean off from vasoconstrictive agents is a commonly encountered problem in any intensive care unit.The exact mechanism is not known.When we are not clear about the mechanism  we  generally blame it on the  the autonomic nervous system !

How common is the mixed shock syndrome ?

This is more common than we realise .The classical description of multisystem failure is a direct consequence of this.

Can a cardiogenic shock transform into a peripheral circulatory shock ?

Such a scenario is  possible  .A  resuscitated cardiac arrest may end up with a recovered heart but a loss of vascular tone  possibly due to hypoxic vascular damage. .Many times cardiac patients are kept (Post PCI/CABG ) on large doses of  vasoconstrictors or IABP that can induce  tachyphylaxis. It may result in difficulty in weaning these drugs.

How can circulatory shock result compromised cardiac function ?

The common effect of any shock is  reduced organ perfusion.So even in peripheral shock , the coronary blood flow gets compromised especially if these patients have a silent coronary lesions which are otherwise not significant , becomes sites of hemodynamic hurdles during hypotension.This may result in global contractile dysfunction, or a coronary event.

What is vasoconstrictive shock ?

Epinephrine and nor epinephrine are  very potent  vasoconstrictors .If levels of these becomes excessively high , the blood vessels go in for sustained spastic state that can impair the micro circulation .Some times  this results  in a  good blood pressure in the major vessels but severely compromised tissue perfusion.This particular situation has been reported after scorpion envenomation , and in  rare cases of pheochromocytoma .

Final message

Primary circulatory failure or shock (With largely intact cardiac function without hypovolemia) is a common problem in critically ill.  The entire  macro and micro vascular tree goes for a  stunning reaction and  goes for  a sleep in a  semi dilated  state  . It can  be termed as  Arterial  or Arteriolar   shock. Contrary to  all those hi-tech   mechanical stuff for supporting a failing heart (LV assist, Impalla, Abiomed , ) the available options are very little here  . The response to vasoconstrictive agents are  also unpredictable. Correcting the multi organ failure  and targeting the primary cause  is the only hope.

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                                                    Drugs are poisons , whenever it is administered without valid purpose. it can enter human body  in many ways (Oral, intravenous, percutaneous etc ) And now we have another route namely intracoronary !

                                                   In quest for prevention of restenosis, many of the anti cancer drugs are now delivered directly inside the coronary arteries .These drugs are secreted  like a sustained release  tablet from the drug coated stents.These drugs are expected to prevent restenosis within the stented segment.But, after years of  intense debate and research  , we realised that ,  drugs  eluted from the stent  could damage the distal coronary vascular bed and coronary microcirculation.( And thus came the epidemic of acute stent thrombosis ! )

                                                The tender and sensitive coronary microvasculature  is constantly exposed to  these  powerful anticancer and immmunosuppresive  drugs .It is a great surprise , no body thought of  this dangerous drug -coronary artery interaction ! It required the genius of Renu virmani and others to point out this.

But still , the cardiology community by and large , fails to consider  this an important issue.This is proven by the fact, usage of DES is  still increasing  and used mainly as an off label indication.

Read this land mark article from circulation




Questions that need to be answered

  • What is the long term effects of drugging a coronary artery ?
  • Is no reflow or slow flow  more common after DES , because of the adverse drug reaction in the distal vascular bed ?
  • If a patient  with  DES  undergoes a CABG later what  would be  the impact of the  drug on the graft ? Will the functional vasodilatation   affected ?

Final message

                                  A drug , to get a legal clearance it has to undergo  hundreds of rigorous tests . Finally it is cleared for that  specific indication for which it is tested  .Just because a drug is cleared for one purpose ( Paclitaxel for malignancy ) it does not mean it is safe to use for any other  purpose for which it is deemed to be useful . Exactly the  opposite is happening   in the  the field of interventional cardiology . No body wondered to think what would be the effect of these drugs on the normal coronary endothelial cells and vasculature.Is it not a crime ,  without analysing this particular issue  , dozens of drug eluting stents have been released in the market . And now,  sounds of crying  foul is heard world wide !

Let us thank  , the so called negative forces in cardiology  for making this an  issue . In science ,  the watch dogs should bark  at  times of danger not wag the tail !

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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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                                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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Differential response of thrombolysis between left and right coronary system

  • Thrombolysis is the specific treatment for acute myocardial infarction. ( Privileged few , get primary PCI))
  • Failed thrombolysis occurs in significant number of patients ( 30-40%).
  • Persistent ST elevation  120 minutes after thrombolysis is best indicator of failed thrombolysis.
  • It has been a consistent observation  failed  thromolysis  is more frequent in anterior   or LAD myocardial infarction.

In a simple study we have documented  patients  with inferior MI  rarely had persistent ST elevation and thrombolysis  was   successful in vast majority  of  patients  ( Except in few patients associated lateral MI)


The mechanism of better thrombolysis in right coronary artery  is simple.The success of thrombolysis , apart from early time window , is directly correlated with pressure head  and the duration of contact between the thrombolytic agent and the thrombus. In right coronary circulation the  blood flow is continuous ,  occurs  both in systole and diastole that facilitates the maximum delivery of the thrombolytic agent . Further there is a favorable  pressure gradient  across RV myocardium  as the transmural occluding pressure across RV is considerably less then LV myocardium.

This paper was presented in the  “Annual cardiological society of India scientific sessions”

at Chennai, Tamil Nadu.India December 2000

Click to down load PPT full presentation

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