Diastolic HF and same LVEDV?

[Daitong]

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Hi,


I know this was mentioned in a few threads back, but I was still a tad confused. I have 3 related questions!

1. In diastolic HF we have normal EDV and EF even with decreased compliance since there is extra pressure (EDP) generated to 'push' the blood in.

What I don't get is why myocardial hypertrophy results in a diastolic dysfunction- does the concentric muscle just take up more room (hence less for blood filling)? But then wouldn't that change EDV (unless the extra pressure (EDP) I mentioned above compensates for it?). If the extra pressure relieves the issue, then what is the problem of diastolic dysfunction if none of these values (EF, EDV, SV) change?


2. Also, is there a difference between acute/compensated/early diastolic dysfunction where EDV is preserved, but then eventually in chronic dysfunction, EDV will eventually decrease (along with a lower SV so the EF is still preserved?)

3. Is it the cardiomyopathy (dilated/hypertrophic) that causes the HF, or vice-versa?

 

[DrPicard]

To understand this in a step-by-step fashion, lets suppose the LV suddenly undergoes concentric hypertrophy. This reduces its compliance, hence, at the pressures that exist in the normal heart, its filling is decreased. Heart cavity size may not necessarily be decreased, but normally the heart stretches a bit under the pressure of the entering blood to reach its usual EDV. Back to the LV: the heart compensates by pumping harder into the LV (this is why you will often seen LA hypertrophy with concentric LV hypertrophy). What this does is maintain EDV in the LV, but at the cost of an abnormally high EDP.

So while EDV and EF might be normal, the key to the presence of diastolic dysfunction is normal EDV in the presence of increased EDP. The increased EDP clues us into the fact that the heart is working extra hard to fill up the LV to normal volumes. Since the body is compensating adequately, the patient probably won't have any symptoms, hence the term diastolic dysfunction. Once compensation is inadequate, ie decompensation occurs, symptoms will occur, and we can label it diastolic heart failure. Pressure reflected back into the pulmonary vasculature will cause pulmonary edema.

In early diastolic dysfunction, EF being normal (EF = SV/EDV) means the SV is also normal, since the EDV is normal. Its just that the heart has to work extra hard, as indicated by the increased EDP. When decompensated, EDV falls while EF still remains normal; this must mean that SV has also fallen. If the EF also falls, this would be systolic dysfunction in addition to diastolic dysfunction.

Reduced compliance of the heart can be due to hypertrophy, infiltration, or fibrosis.



Heart failure is the possible end game for any cardiac pathology; its the point where the heart is damaged to the point where it "fails" to function adequately. Valvular diseases, ischemic heart diseases, cardiomyopathies, myocarditis etc, anything that can damage the heart sufficiently can lead to heart failure. Heart failure is a syndrome, not a disease, so what we have to do is pick out the signs and symptoms to identify it, and then work out the underlying cause.