Heart Failure Question

[drLexus]

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I recently encountered a funny question describing a patient with a heart rate of 120, a dilated left ventricle, and an ejection fraction of 30%. (normal ~50%)

I was stuck between two choices asking what the cause of his heart failure was:
either decreased ventricular filling or decreased contractility.
Both seemed to make sense, since a rapid HR would decrease filling, and a dilated ventricle would decrease contractility.

is there a reason for choosing one over the other?
Thanks in advance.

 

[loveoforganic]

I think you have to consider the etiology. How'd the ventricle get dilated if there was decreased filling?

 

[drLexus]

I apologize, I think the question was actually asking for the cause of his decreased Ejection Fraction.
So he came in with heart failure as a given.

 

[lstone13]

According to FA, EF is an index of contractility... So... I'd go with the decreased contractility answer. 🙂

 

[Aclamity]

EF < 40% indicates systolic dysfunction, so decreased contractility. Impaired filling is characteristic of diastolic dysfunction (but EF would be normal in this situation)

 

[Boardz]

yeah, ejection fraction has nothing to do with heart rate. Even if it's beating at 120bpm, the Cardiac output will be low because of decreased diastolic filling, but the ejection fraction (Stroke volume/preload) is unchanged.

With the dilated LV, I think contractility is the issue, thus the lowered ejection fraction.

 

[OveractiveBrain]

I recently encountered a funny question describing a patient with a heart rate of 120, a dilated left ventricle, and an ejection fraction of 30%. (normal ~50%)

I was stuck between two choices asking what the cause of his heart failure was:
either decreased ventricular filling or decreased contractility.
Both seemed to make sense, since a rapid HR would decrease filling, and a dilated ventricle would decrease contractility.

is there a reason for choosing one over the other?
Thanks in advance.

The question is asking "does he have systolic (contractility) failure or does he have diastolic (filling) failure?" Decreased EF means systolic failure, by definition.

The question you are asking is "doesn't an increased heart rate decrease filling time, and so the answer should be filling time?" And the answer is probably not at 130; while it is true rapidly beating hearts have less time to fill (which is why Afib with Rapid Ventricular Response causes syncope, shortness of breath etc), the 130 is likely compensatory for a decreased EF. If they wanted you to think of preload and heart rate, they would have given you a heart rate > 150. You are correct on the concept, wrong in this particular example.