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Posts Tagged ‘dilated cardiomyopathy’

We generally believe ischemia and it’s clinical counterpart  angina would  go together .It is not true .Most patients with ischemic cardiomyopathy do not have any significant  angina in spite of  having one or more critically  narrowed coronary arteries.

The reasons could be many ,

  1. Little viable tissue to generate Ischemia.
  2. Less contractile elements and less MVO2 consumption.
  3. Severe LV dysfunction makes these patients adopt a very restrictive lifestyle.
  4. Loss of nerve fibers  along with myocyte necrosis and apoptosis.
  5. Post CABG patients often have no angina due to denervation..

The benefits of revascularisation in ischemic DCM is not clear. As the cardiomyopathy  progresses , intensity of angina regresses and dyspnea dominates .Presence of angina makes the decision to  revascularise easy .To consider dyspnea as an anginal equivalent in ischemic DCM and advising revascularisation can not be  justified .

 

 

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Inserting an ICD  for  DCM  may a be great therapeutic success  for the physician  as well as the patient . But there is one big truth hidden behind the statistical screen.

Following  study  provides dramatic data from Maanhiem in Germany in about 561 patients who had ICD .The long term patient outcome after appropriate shocks were much worse  than those without    shocks .This was more pronounced in Ischemic DCM .

appropriate and inappropriate shocks ICD

Source : Streitner et al ,University Medical Centre Mannheim, Mannheim, Germany PLoS One. 2013 May 10;8(5):e6391

The fact that these patients continue to throw VT , some thing is wrong in the cellular  milieu or a fresh scar / fibrosis / ischemia is progressing .Further , the VTs and the  subsequent  shocks  set in temporary  hemodynamic instability .We have evidence , EF can be depressed for days  worsening the long-term out come.

While it is easy  to blame it on natural course of DCM , there are  solid reasons to believe  , shock induced myocardial damage is definitely contributing to this  excess mortality.

One important  clinical tip is to screen  all  these so called Idiopathic DCM  patients  who  had appropriate shocks.  They should be monitored for fresh signs of any systemic illness  , like a  connective tissue disorder , chronic granulomatous lesions  like sarcoid etc .To our surprise  some specific  myocardial disease may unmask themselves in the natural history. Identifying them may offer a dramatic cure .

Final message

Some where along our EP mind-set  we are conditioned to think  , as along as there is an ICD in situ and it appropriately  shocks, every thing is bliss ! Blame it  on semantics . The  word “appropriate”  inappropriately  soothes  our nerves.

The fact of the mater is , every appropriate shock is a  grim reminder  that the heart  in question  is restless electrically and VT continue to emanate  from diseased  myocardium  . It could  mean either the LV   is destabilising  , or the original  disease  is   progressing  or a new disease  is evolving .

Mean while, paradoxically , inappropriate shocks give us a quixotic comfort , since the  heart is not really  throwing any dangerous arrhythmia, after all it is  the device related  false alarm   that  could be easily  reprogrammed!

Reference

ICD appropriate and inappropriate shocks

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Here is a patient with class 3  dyspnea  who was referred  for echocardiography

X ray chest showing cardiomegaly

         Moderate TR due to dilatation of tricuspid annulus.This patient had dilatation of all 4 chambers of the heart.LV EF was 24 %

Right ventricular dysfunction is major determinant of  clinical outcome in patients with dilated cardiomyopathy. The  myocardium of the  entire heart is now known to be a single sheet of muscle rolled into different chambers . So any primary disease of myocardium will involve the entire musculature . This is the reason  , all the  4 chambers of heart goes for dilatation in  primary cardiomyopathy . Of course there can be minor variations  due to differential hemodynamic impact.

But it is certain ,  RV  function will definitely be compromised  In  most patients  with  Idiopathic DCM (Less common in Ischemic DCM ) Rapid assessment of RV function is difficult  . Of course We have some clues .

2 d Features

  • Simple dilatation  of RV is suffice to say it is struggling with the  loading conditions
  • Septal bowing
  • Tricuspid annular dilatation
  • RV ejection fraction (Continues to be complex for routine usage )

TR jet

  • Dp/Dt
  • Morphology may be useful (Mainly for TR severity )

Tissue doppler

  • TAPSE
  • RV strain rate Imaging etc.

And  now  , we have observed a new echocardiographic  sign   ie  TR jet alternans  in patient with  DCM .

Note the changing TR velocity implying severe RV contractile dysfunction.

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Caution: This is a fairly lengthy article . Optimal Reading time  15  minutes

Cardiac failure is a progressive systemic disease  ,  even though the primary problem originates in the heart .Most of the symptoms and clinical features are related to Neuro-Endocrine activation instigated by poor pumping function.When the diminishing cardiac function exceeds the compensatory mechanisms , full blown cardiac failure sets in and get into a vicious downward spiral unless  intervened.

The conventional treatment model involves  on three targets.

  • Reduction in pre -load(Diuretics)
  • Improving  contractility (Inotropics)
  • Reduction in afterload  (Vaso- dilators)

Though the concept looked attractive  there are many missing links . Medical treatment   lags far  behind  the desired goals. Still , it  can stabilize most of the patients with cardiac failure till they reach very late stages.

Nomenclature

Inadequately  treated  CHF is not  synonymous  with refractory failure  . But  ,  practically it is the commonest cause for refractionaries . Hence  , every patient must be scrutinised meticulously for adequacy of treatment.

Primary mitral  , aortic valve  lesions causing cardiac failure need  not be considered as refractory  cardiac failure . In the strict sense myocardial disease /damage  either  idiopathic or secondary to CAD  would form  bulk of refractory failure .

(For example a patient with critical aortic stenosis with severe LV dysfunction is   technically  refractory cardiac failure but functionally it could be a  simple  expression of  after load mis- match )

COPD -Cor pulmonale /Primary pulmonary  hypertension  / End  stage congenital  heart disease  and   Eisenmenger syndromes   form separate  group of  CHF and would not be discussed  here.

The valves , the fibrous skeleton, the  pericardium are integral parts  of the heart . Individual disease process can affect these compartments in a differential pattern .

When we  refer to  refractory heart failure   it amounts only two  large disease groups.Ischemic and idiopathic  cardiomyopathy.The whole myocardium is a single unit. If it is destined to fail  it will fail in toto.  There can be reversible factors that can be addressed.

The coronary artery   though not a part of heart has a major say in the outcome of cardiac failure as they determine the cardiac muscle  integrity.In every patient with refractory cardiac  failure , an attempt must be made to rule out  any  re-vascularisible  lesions.

The primary difference between ischemic and Idiopathic DCM   is ,  in ischemic DCM left ventricular  segments  are predominantly involved . RV function  is relatively   preserved until very late stages.

Patient factors

Age , gender, body weight , systemic illness that increase metabolic demands have an adverse impact . Diabetic patients fare poorly .

Fluid management  and  diuretics

In refractory cardiac failure the renal blood flow is reduced .Diuretics usage will further worsen this if ECF is depleted .

So it is obvious we have to use it very judiciously .

Why only  certain patients with cardiac  failure   develop significant edema while others do not ?

This lies in the response of neuro -humoral  activation of secondary RASS system.

Both inadequate  and excess diuretic can perpetuate the  status.

Intra vascular hypovolemia and effective renal blood flow reduced

Diuretic strategies

  • Increasing the dose
  • Adding another ( Switching over to another loop diuretic like Bumetanide, or Toresemide  can be tried )
  • Sequential nephron blockade ( Add  metalazone a powerful thiazide acting in proximal tubule  to be used with caution risk of hypokalemia)
  • Continuous IV infusion  is an option

Ultra filtration  can be  used  in severely volume over loaded  patients.

Refractory diastolic failure .  How common is that ?

The incidence of significant LV filling defect are more commonly observed.There is no specific  drugs  available to tackle this .It may be argued digoxin and other positive inotropes worsen diastolic dysfunction.This  may not be true in the bed side.Unless severe  LV restriction feature are present  digoxin can be continued.

The simple and effective way to improve LV filling in the presence of diastolic filling defect ,  is to slow down the heart rate. At low heart rates  diastolic filling period prolongs and dysfunction tend to vanish.Beta blockers usefulness  in   DCMs  is attributed to this phenomenon

Specific  therapeutic targets

RV dysfunction

RV dysfunction is responsible for systemic congestion .RV function improvement alone can improve the functional class in  many .Controlling and targeting pulmonary hypertension is beneficial . There can be a role for off  label use for chronic pulmonary hypertension associated with DCM.

Importance of  weight reduction :

We can comprehend  complex equations  in  cardiac failure  , still we often  forget a simple logic  . Body wieght is an  indirect but powerful determinant of aortic after load.  A 80kg body needs more heart power than a  body with a 40 kg  mass. If a  patient with EF of  25 %  loses 50 % of his body mass,   his heart can serve  his body  for   100 % longer duration.   (Of course ,  this happens  in certain patients  by a mechanism  called  cardiac  cachexia !  shall we call  it as  natural adaptation ?  )

 Inflammation   control

Tumor necrosis factors and Interleukins are responsible for systemic reaction . These levels are high in CHF. Anti -Inflammatory drugs and diet would help. Statin usage is shown to be beneficial.

Metabolic modulation

ATPs ,fatty acid are fuels for the  heart .Ailing hearts  require  it in plenty. Certain drugs like Trimetazidine, L carnitine has been shown to be useful .

Cardio-Renal syndrome

This is nothing but raising renal parameters  as heart failure worsen .This  essentially  involves fluid and electrolyte management.

Natural course of refractory cardiac failure

It is sort of a  delayed near death sentence . 5 year survival is comparable to many cancer inflicted patients.Basic medical care  remain the corner stone. CRT /ICD*  , LV  assist devices are slightly more effective with substantial  risks and cost involved. Indicated only for  rich  and  insurance infested  population who can tolerate both scientific and  financial excesses.

ICDs* do prevent sudden electrical deaths.

 There is a  fundamental flaw  of  electrical and mechanical device concepts  in refractory heart failure .It  forgets  ,  CHF is a  systemic disease .A  cardio centric approach rarely works to perfection .

Cardiac transplantation  is the ultimate . It works well beyond any doubt. In best centers  like  Stanford 85 %   for 5 year survival is expected. Heart transplantation is limited by donor  availability and  surgical infra structure.Total artificial heart is a distant dream , but will be definitely accomplished

Role of surgery

CABG ( Strictly Indicated only in absolutely deserving .The habit of  revascularising scarred, akinetic DCMs to be abandoned )

Ventricular reduction( Batisda -seems to work only in Brazil!)

Mitral valve  interventions

Some  exotic interventions in cardiac failure

Mitral splinting to  reduce secondary mitral regurgitation in DCM

 

Newer drugs  and experimental drugs

Nesiritide, (Synthetic Brain naturetic peptide )  Tolvapton ( Vasopressin antagonist) are used with varying  success .


20  point bed side prescription tips  for refractory failure.


  1. Correct the  underlying causes  and triggers.Try to correct any  critical coronary lesion if any by PCI /CABG ( Not a major game changer ! )
  2. Restrict activities (Better to remain in class 3)
  3. Admit  only if  persistent  class 4 .(Intermittent class 4 does not require admission )
  4. Do not try vigorously to move up to class 2  with inotropes  you may  end up in class 4 !
  5. Advice mild passive and active movements. (6 minutes walk > 300 -400meters)
  6. Educate the entire  family / Ask them to shun Internet  (Internet acquired half baked medical knowledge is more injurious to health )
  7. Restrict salt intake
  8. Continue  Digoxin till toxicity develop  or maximum  dose  is reached  (Milrinone /Amrinone make  no major difference )
  9. Optimse diuretics.  Add Metalazone to Frusemide.
  10. Maintain good hemoglobin level (Erythropoitin does not work !)
  11. Add beta blockers  in every one including many of the  class 4 (Not necessarily Carvidilol)
  12. ACEI remain a key drug . Titrate to maximum tolerated dose. (Additional ARBs not much useful)
  13. Aldosterone antagonist has  unique role (Anti-fibrotic ? )  Caution required in diabetic patients  in monitoring renal function .
  14. At-least One metabolic modulator like  Trimetazide  could be tried (ATP utilisation amplified)
  15. Fatty acid metabolism enhancer  L carnitine  may be useful (Recall 1st year medical school basics  . . . Heart thrives on fat energy more  !)
  16. Nephrologist consult  is recommended if electrolyte / ECF status fluctuations are more.
  17. Avoid dobutamine infusions unless patient  insist.
  18. Narcotics like morphine can be used liberally in terminal heart failure  (Both for hemo-dynamic  and  neural benefits )
  19. As far as possible do not send these  patients  to big tertiary hospital unless heart transplantation is planned.
  20. Don’t  be a party  in  exhausting the  personal finance resources of the patient by ordering exotic investigations . Let him not suffer from additional worry ! (By the way . . .  having a hefty health insurance limit  is not an excuse  . Depleting  it  for futile purposes   would make the national economy weaker ! )

Final message

 Three  principles of  management in  refractory  cardiac failure  

  1.   Systemic approach  is the key .
  2.   De-mystifying   cardio centric  interventions  is essential.
  3.   Psychological support is vital .

Functional capacity   has a  poor correlation with LV contractile function . The skeletal  muscle  integrity , blood flow , and its  metabolism has critical say in this. Optimal medications  , properly regulated  locomotion  , weight reduction   can have a major impact.

The secrets of living a good quality of life    in  cardiac failure   ,  lies  not in modern technology  but in the  rare commodities  called  common sense and compassion.

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Human heart is a compact elastic organ .  We know elasticity is lost when it is stretched beyond a point.This is what happens in dilated  cardiomyopathy .When the heart muscle fibers stretch  too long from the baseline  it loses its ability to contract and relax   efficiently.In fact  , after a cut of point even if it comes the original length the elastic fibers are fractured and suffer from irreversible damage.

Among  the systolic vs diastolic dimension it is the diastolic dimension that becomes important in defining dilatation.

When do you say a ventricle is dilated?

  1. When the EDD (End diastolic dimension) > 60mm
  2. EDD > 56mm
  3. EDD > 10 % from baseline
  4. EDD > 25 %  from baseline

Any of the above can be right.

The normal human ventricle measures  between 35 to 55mm in diastole .

Currently accepted  definition for enlargement of heart is EDD  of 56 mm and above. Some believe  in a more strict criteria of 60mm.

Consider the following situation

A man with 35mm EDD   can increase 20mm ( ie 60 % )  from of his baseline  and still be  labeled as  normal LV  dimension ! . If the above patient  is  destined to develop dilated cardiomyopathy    his  heart  would  begin  its  final  journey  slowly but   surely ( from 35 mm  ! ) . So ,  according to current criteria  we can diagnose  DCM only after it travels the half way towards hell .   What a way to define DCM  ! Be cautious LV dimensions can fool  you  . . .

If the EF is low and symptoms develop early ,  one may recognise  the above  entity ( at least erroneously !) as non dilated cardiomyopathy or RCM.

If  the patient is relatively asymptomatic and   if we   overlook  the  baseline  LV parameters ,  we are likely  to miss  most of the early  DCMs

Final message

We need to stress the importance of baseline LV dimension in defining DCM  . It is proposed  from this  site ,  an increase of 25 %   and above from baseline  can be   included as an   additional  criteria  for  LV dilatation . This  could  help us understand   the early muscle dynamics in DCM.

Un-Answered questions

  1. How to diagnose  early DCM ?
  2. When does the EF begins to decline in DCM ?
  3. What is the relation between EDD and EF %?
  4. Is HF with preserved LV function ( previously called diastolic dysfunction ) is the earliest point in the natural history of  DCM
  5. Is there a overlap  between non dilated cardiomyopathy , RCM and early phase of DCM ?

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As the name suggests   dilated cardiomyopathy  would imply  cardiac chambers will dilate , at least some time in the course of the disease .It can be minimal, mild or massive. A new entity called  non dilated cardiomyopathy is also gaining wider acceptance . (That will be dealt seperately )

Logic would suggest , the first chamber to dilate in DCM  should be the left ventricle because it is  facing the direct load of systemic blood. But we also know , whenever  LV is stressed , left atrium comes to it’s assistance .

Left atrium does this    by total self sacrifice ( by all  means!)  increases  it’s  force of contraction, elevating it’s  mean pressure or even increasing it’s rate (AF) .

Like most  other critical questions in cardiology  ,  the factors that determine LV dilatation in DCM ,  is  also poorly understood !

  1. Is it the after load ?
  2. Is it the  muscle mass ? or it’s turgid  or flabbiness ?
  3. Is it the interstitial integrity?
  4. Is it the blood volume ?(LVEDV ,  LV residual volume )

When the issue is complex , it is  usual  to  make the   the unknown  genetic defects  ,  the scapegoat !

As of now the most important determinant of LV dilatation  could be  the behavior of the desmins, the gap junctions and myosins the titins etc

If  the LV of a DCM patient  refuses  or  resists  dilatation what  might happen ? Is it good or bad for the patient ?

Here is a catch .  A  LV  that does not dilate  obviously should be  be good for the patient  is in’t ? Medicine is not that simple.

When   LV  fails to  dilate  it means it has become  too  stiff and rigid    and pass on the  burden to  to LA which  faces the music. And in the process it dilates.This is the reason , we  observe  diastolic dysfunction in vast number of DCM patients.( Currently it is estimated > 75% DCM will have significant diastolic dysfunction )

So , now we can imagine how complex the sequence of hemodynamic stress in DCM that determine the chamber enlargement.( RA, RV  dimension in DCM is a separate issue !)

So now answer this question :  Which chamber dilates first in DCM ?

  1. Left ventricle
  2. Left Atrium
  3. Any of the above
  4. Both of the above dilate simultaneously

The answer must be 3 .

Why  recognising this sequence of  chamber enlargement  in DCM   is important ?

  • It gives us an opportunity to assess the dominant mechanism of LV dysfunction.There are reports , where some  DCMs  have more diastolic dysfunction than systolic dysfunction  .This will have important therapeutic implication.Further , many of the infiltrative   disorders of LV can have features of both DCM & RCM .
  • When a RCM begins to dilate it is usually  a harbinger of terminal heart failure. But,  it need not be always true .  A small restrictive LV  , when  dilates ,   may acquire a  slightly improved diastolic properties , as the  LV becomes more placid . And ,  if it happens the LA size may regress.
  • The role of LV restriction devices like, Acron mesh, Dor procedure, plication  in refractory  DCM is not well defined. All these   modalities actually  adds  a small dose of diastolic dysfunction in these patients who have grossly dilated ventricles. This fact is  very important  , as presence of any preexisting  significant diastolic dysfunction in DCM makes  the role of LV restrictive devices and surgery a big question mark !

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It is a well known fact  ,   CABG and PCI  provides immediate relief  for patients with angina ,  which is refractory to medical therapy. Of course , this happens only if a critical occlusion of  at least one epicardial coronary artery is  opened . It need to be realised ,  angina  due to  microvascular  disease can not be cured by maintaining  epicardial  patency .

While angina  relief is prompt ,  dyspnea is not ! . If we  believe,  opening  up a  coronary artery  in a patient with LV dysfunction will  restore the LV function  ,  it  is grossly mistaken !

Why is it so ?

Angina  relief requires  simple  restoration  of  oxygen supply and correction of local ischemia .  This happens without any issue as the blood  seeps in to the ischemic cells and soothes the ischemic nerve fibres that trigger the pain signals   . While  ,  for LV function to improve , the blood flow has to be converted to mechanical activity in the form of myocyte actin/myosin interaction. For this,   there need to be an intact  cellular contractile mechanism . The myocyte architecture should be appropriate .In post MI ventricles we know there is  zig zag  orientation of myofibrils due to myocyte slippage that interfere with mechanical recruitment . Further , integrity of  extracellular matrix  namely the collagen frame work is also vital . Note ,  angina relief  is not concerned with any of the above .

And now ,  we also realise  dyspnea  in failing ventricles  is vitally  dependent on diastolic function ,  which is also very much  impaired in ischemic DCM .There is little proof for  PCI/CABG  to correct the  molecular   mysteries in  diastolic dysfunction !

Dysfunctional LV means what ? (read the link )

It is a collection of  variety of myocardial tissues . Viz : Fully  necrosed , partially necrosed ,  ischemic viable, non ischemic viable, ischemic non viable, non ischemic non viable , Apart from this patchy necrosis, patchy ischemic, areas are common. Finally , necrosed segments   may  also be perfused normally by  spontaneous reopening of an IRA.

One can imagine the complexity  of events in these segments  once we do the  PCI /CABG . The response  is highly variable and unpredictable. The major concept we  , the physicians  believe or ( to be precise made to believe !) is  the  sanctity  devoted to  the viable myocardium .For  many us ,  it is considered a  holy  exercise  to identify viable myocardium in patients following MI and then revascularise them if  found to have significant viable myocardium (Atleast 20% of infarcted area )

A full 2 decades were lost or (shall  we   say wasted on this futile exercise !) as   we have since  realised most of the cardiologists do not follow this rule .

Now , even a scarred myocardium is revascularised in the hope of recovery .As such , we have reached a stage where  there is no contradiction for not doing a PCI /CABG   with reference to LV dysfunction.

Now every  patient  with post MI  LV dysfunction  is considered to  have  some amount of viable myocardium that is  fit   enough  for revascularization

Are we justified in doing  this ?

Many clinical  trials  have revealed  , the  recovery of LV function  in these segments  has not been consistent at all .

The most surprising discovery is  a viable myocardium need not  be ischemic   .It might get adequate blood supply either  from invisible collaterals or trickle of antegrade flow .  Hence an adequately  perfused myocardial segment can  still be   non contractile . This shatters the myth  that  revascularisation must have a dramatic effect on the recovery of contractility in all viable segments.

The other major finding is  ,  even ischemic   viable   myocardium ( documented by metabolic activities PET etc)  need not regain it’s original contractility  after the ischemia is fully corrected .

*reference for  both the above statements are available from variety of sources including real life experiences .(Type C evidence )

Final message

  • Do a PCI/CABG promptly for patients with refractory angina.
  • Never  advocate PCI/CABG  for  a primary relief of dyspnea .  (Never is a harsh word,  let it be  “use it  with caution ” ! and  the  patient  should be  revealed  the whole facts  about  what we know and what we do not know regarding the complex  hemodyanmic events  in  revascularisation   )

Counter point

If  the above statements are really true ,   How does PCI/CABG   help  relieving  dyspnea  and functional class  what is your answer for thousands of patients  with CAD and ischemic DCM who have greatly benefited from CABG ?

The answer could  be  simple , The revascularization  piggybacks  over the   medical management (which , these patients pursue vigorously)     like  ACEI,  statins, salt restriction, betablockers  , optimal diuretics and tend to hijack the credits from the poor  drugs !

Read a related blog

Revascularisation for ischemic DCM

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