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Posts Tagged ‘lv assist device’

                                                     Every day thousands of  hearts  end their life   due to terminal heart failure . Much more  lives are  confined  to their bed rooms.In refractory cardiac failure and severe LV dysfunction the only  long-term option is cardiac transplantation.

Medical therapy has reached its saturation point.  Neuro- humoral modulation shows some promise. The other modalities like cardiac resynchronisation ,LV assist devices ,  ventricular  reduction surgeries ,  restriction devices , mitral valve splinting  are  still experimental .

Simply watch this Image : Your heart will get Energy

Modern day  cardiology is trying to add life to these dying  hearts  .

There are two aims

  • To prolong survival
  • Improve functional capacity (Make them at least take care of daily activities and live a fairly independent live)

This is the purpose of the  mushrooming heart failure clinics all over the  world . These clinics , though started with  good intention , ultimately   become  feeding  centres for so many experimental  bridge modalities  , sometimes  with an  infinite wait for  a potential donor  or at the mercy of their insurance companies  . (Many time it turns out to be a  bridge to heaven as the patient fails to cross it !) .

Even though there is strict criteria for terminal  heart failure ,  in practical terms it has many issues .Temporary functional deterioration is misinterpreted   often .

Premature  dependence on LV assist devices and  indulgence  in inappropriate  mitral valve reconstructive  procedures are the currently most important pseudo cardiac interventions .( Myosplint/AV groove tying etc)   Some where along   the  academic  corridors ,   we failed to realise many patients can bridge themselves  to a  transplant (or even   self de-list  from transplant programme  )  provided we are willing to wait and take few   risks  .

It is observed exercise training  programme is awfully inadequate in most centres  who deal with late stages of cardiac failure.

The hidden link  between skeletal muscle and  cardiac muscle

Skeletal muscle  function is impaired in cardiac failure . This impairment is attributable  to both  dis-use and low cardiac output.  Proper training of these muscles can not only improve the functional capacity  but also  sets in  a positive hemodynamic cycle  that   ultimately improves cardiac function as well.

In  our  country we have data  of  thousands of patients  with severe LV dysfunction living with the much ridiculed  digoxin   ,   diuretics ,  ACEI  and minimal exercise living a comfortable life for over 10 years .  It is often said in  cardiology class rooms ,  do not whip a tired horse  as the   failed heart needs rest  .This statement  has  truth  in it even in  this  space age cardiology !

Whipping  a failing heart with electrodes in the name of CRT   could be as  bad as  whipping with inotropic agents . This is not a  personal joke ! This fact has been repeatedly  proved by various inotropic  studies in terminal heart failure(Dobutamine to be specific ) Even CRT  is a suspect .These patients walk for 30 meters  further  with  no convincing survival  benefits .(Of course it requires a ICD -Combo to prevent sudden deaths ) Zero impact in non sudden deaths ?

Can  we propose a  new therapeutic  concept to our  patients   ?

Do you  want to   live with a  low functional capacity (Restricted  life   still  happy  )    for 5 years   or live  apparently unrestricted  life   and die prematurely ?

                         In simple terms,  for all those patients with severe  grades of  heart failure   the  best advice could be . . .to  avoid the levels  of exertion that cause dyspnea / Modern gadgets  may help relieve  exertion for a short  while  , but it  can cut short your longevity * (* This is not a threatening message. This applies to near terminal stages of cardiac failure .All other minor grades of CHF are encouraged to exert up to 70 % of their limits.)

Peripheral mechanism in cardiac failure.

We know cardiac  failure is not a simple  mechanical failure of heart , it activates a complex neuro endocrine system which makes it a systemic disorder .Many of the current research is aimed at favorably modify this. It is now certain Skeletal muscle function is a  major determinant of  cardiac failure outcome and hence a therapeutic target .

If you have good muscle mass ,  good diaphragm and intercostal muscles one can  compensate the compromise inflicted by the heart to a large extent.  We know,   the entire vascular tree has a mechanical function  to do . The stiffness and compliance of aorta , other  major vessels, the muscles  through which these vessels  traverse determine the  ultimate  efficiency  of  circulation.We know  the pulse wave , as it  travels to the periphery , gets amplified. This amplification is not without any significance. It aids in muscle  blood flow . This agumnetation is missing in poorly trained cardiac failure patients. Further muscle respiration is synonymous with  functional capacity . Numerous defects (Both structural and functional )  in skeletal muscle mitochondria are reported.

This is why meticulous  exercise training  becomes an important   intervention in  cardiac failure . There are very good studies that document   muscle respiration defects  getting reverted  with  proper exercise training and  muscle  care  .  Among all muscles the   calf  and thigh muscles show great promise.   We have observed  cardiac failure patients  with good calf muscles ,  outperform others with identical ejection fraction.(Will be published shortly )

Strangely there is no comparative  studies between calf muscle  efficiency   and other available modalities  in cardiac failure .

The concept of  Venous pump vs  Arterial pump

Skeletal muscle mass acts not only as venous pump  it also has a modulating  effect on the arterial pulse transmission .A good venous  pump will activate  vascular  tone . In congestive heart failure  a the RV filling pressure is raised,  blood tends  to  move sluggishly  in right heart chambers .  A proper venous tone  can alleviate this . Well trained  calf muscle  can exactly do this  by a controlled elevation  of  IVC pressure at times of exertion . 

 Dyspnea  of muscular  origin (Peripheral dyspnea)

The symptomatology of cardiac failure has an intimate  realtionship with skeletal muscle integrity  !

Lactate in blood and  hypoxia  in   exercising muscles  can trigger   non hemodynamic dyspnea . Further , there is strong reason to believe  the sensation of dyspnea   is perceived at the chest muscle level  (By muscle spindle length/tension   mismatch ) .It is not known whether lower limb  muscles can generate a feeling of dyspnea  !

But , one thing is certain   by altering the tone of the muscle  spindle and the  optimising the  stretch signals the peripheral component of cardiac dyspnea can be significantly neutralised . This  is what  happens in well-trained   cardiac  failure patients .

How to train the skeletal muscles ? ( In to heart friendly  muscle )

  • Passive stretch
  • Simple 6 minute walking three times a day will help .
  • Muscle massage and toning
  • Drugs like Trimetazidine may improve muscle metabolism by better ATP utilisation
  • Diligent use of diuretics (Excess diuretic can make your muscle exhausted )
  • Chest exercise for improving intercostal muscle function

 

Final message

Skeletal muscle training  in cardiac  failure  could be as important as  the  digoxins  , diurteics   and ACEI .When a 300 grams of heart muscle is struggling  , God  is willing to  help  it with huge muscle mass that lies elsewhere , we should read the silent  signals of nature . Many cardiac failure patients  realise this and live  a happy live without artificial assistance .This applies  in all grades of cardiac failure .

For  all those physicians  out there in modern hospitals who treat cardiac  failure , spend at least  few minutes  for prescribing a good exercise  program with a specific  mention about calf muscle function  . After all , it  may turn out be the most efficient  RV/LV assist device !

References

                                                                     http://content.onlinejacc.org/cgi/content/abstract/30/7/1758

 http://www.uptodate.com/contents/skeletal-muscle-dysfunction-and-exercise-intolerance-in-heart-failure

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We have conquered  CAD with coronary  stents !  really ?  atleast , that is  what ,  many  of us  are made to  believe !

But , the fact is , modern cardiac science  with all those fancy intra coronary  devices has shifted the CAD population into  cardiac  failure population. We have extended the life of humans by at least few years and make them suffer recurrent coronary events and ultimately LV dysfunction  and cardiac failure .

We know , cardiac  failure  can not be  conquered with medicines and surgery . Cardiac  transplant  has been very successful ,  but it needs one human death to give one  life to other , and “deaths” can not be bought in stores or  donated at will !

So , the only alternative for  terminal heart failure  is total artificial   heart.(Organ farming or cloning not included ) The research is going on for the past 50 years. We are definitely on  the right track. By 2050 , my guess is  no human being  should die of heart failure .

Meanwhile , number of partial answers for  failing hearts  which are  popularly referred to  as LV assist devices are coming up.

In many cases the failing native heart supports the device  in a mutual fashion thus extending the life of the device as well .This is important because in case of total artificial heart there  is no back  up available.

These axial LV pumps just augment the overall circulation status and in the process unloads the native heart and prolongs it’s running time.

In the future one may think about  number of serial pumps in the circulatory  system rather than a single bulky artificial heart which is fraught with serious maintenance issues.

The most promising one such device is from Germany

  • A small AA battery sized tubular pump
  • Weighs 25 grams
  • Receives blood from  left atrium  pushes it into subcalvian artery
  • Can have a stroke volume of 10-15cc /beat*
  • Capacity to pump  a cardiac output of 3l/mt (This amounts to 100% augmentation in most terminal heart failure patients)
  • Can be implanted like a pacemaker

* There is little  end diastolic  residual blood in this pump .

Picutre courtesey  www.medgadget.com

Link to  http://www.circulite.net

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