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
- It is the inability or reduced capacity to pump that affect the tissue oxygenation.
- 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
Dr.S.Venkatesan MD 