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Intriguing concepts in cardiology :Anemic heart ! Is it cardiac failure or cardiac success ?

Posted May 27 2010 10:06am

Anemia is one  of the earliest human diseases  that was identified. Traditionally  heart disease and anemia have a  close relationship.(Is it a true relation ?)  .Most of  us  are made  to  believe so, by meager speculation !

In what way anemia is linked to heart failure?

The answer is explicit  in the definition of cardiac failure . There are two components to cardiac failure

  1. It is  the  inability or reduced capacity to pump  that affect the tissue oxygenation.
  2. Or able to do so only at the cost of elevated  filling pressure.

Do they  happen in severe Anemia ?

Even though anemia partially and indirectly   fulfills    first  half of the definition , it fails to result in elevated filling pressure of the heart. Hence anemia per se ,  may never* result in cardiac failure by definition.  

*Is there an exception to this ?

Severe anemia( Hb <  5 grams ) is often  thought to result in cardiac   dilatation .At this point of time ,  some consider cardiac failure to be present.

When does anemia produce a hypoxic injury to myocardium ?

Hypoxic injury to myocardium due to extreme anemia is possible .In clinical practice it is rarely experienced.

What is the effect of anemia on ECG ?

Anemia is probably the commonest cause for the so-called non specific or( non ischemic) ST depression and T wave inversion. These changes are more pronounced in females. When sinus tachycardia also co exists (Usually it is )   ECG can perfectly mimic an acute coronary  emergency.One should watch out for this possibility.

Anemia and  echocardiography.

  • Anemia causes mild enlargement of all cardiac chambers.This is  first seen right-sided chambers.
  • The ejection fraction is  in the   higher ranges of normal ,  often hyper functioning  and super normal EF (75%) are recorded.(Anemic heart contracts vigorously  ! where is the question of failure ?)
  • Diastolic dysfunction is almost unheard in  anemia .As quick relaxation must be there to augment  the next contractile beat.
  • Anemia can cause high velocity turbulence across LV outflow( or even in the AV inflows.) This turbulence is seen as color variance in color doppler. But , since it is physiological , the flow velocities are not elevated much .

Anemia and coexisting CAD .

This is a distinct possibility , as both entities are quiet common in general population. In fact, anemia  will worsen the underlying CAD. Anemia is an important  cause of   secondary unstable angina.Here, one should realise it is almost impossible for anemia alone (without CAD )to produce unstable angina .Even stable angina is rare in isolated anemia .If it occurs, anemia unmasks silent CAD.

Anemia and associated cardiac failure.

This has probably confused us a lot. They are often associated but the former plays an amplifier role  than an etiological role.

Cardiac failure triggered anemia

It would be a surprise , when the discussion here is “Anemia causing cardiac failure”  the reverse situation   could be much  more common. ie  ”Anemia occurring due to prolonged congestive failure” .  The bulk of the knowledge we have is related to this question . It is  similar to  anemia of chronic disease (Hypochromic , microcytic )  as in rheumatoid arthritis,  CKD etc. This fact is  being  exploited by the industry  for quiet  some time now  (Oh , a mouth watering role  for erythropoitin in CHF ! ) .It (Amgen EPO )  miserably failed according to  available inputs.

Anemia begets cardiac failure and cardiac failure begets anemia

There could be some truth in this conceptualization  even though anemia can not make a myocardial contraction directly.

Final message

Anemia  with cardiac failure is not a  true cardiac  failure . In fact , it is not cardiac failure at all in many  situations. Only in terminal state , the heart begins to dilate .Till that time the heart is actually in the hyper functioning mode.

So , to call anemia as cause of cardiac failure is a misnomer . Ironically, in patents with  isolated severe anemia the heart   more often succeeds in its  assigned job of  supporting  the  heamic system in it’s  hour of crisis.

Reference

1 . Anemia in heart failure :A review


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