MODULE SUPPLEMENT: CARDIOVASCULAR SYSTEM
Diastolic Versus Systolic Heart Failure

About 1/3 of patients with symptomatic CHF have a "normal" Ejection Fraction (EF at least >40%) and experience symptoms that are entirely or predominantly the result of diastolic dysfunction. However, about 50-60% of elderly persons with heart failure have adequate ventricular contractile function and are thus experiencing mainly diastolic dysfunction (Kitzman, 2002).

CHF secondary to systolic dysfunction is the result of an impaired inotropic state; this is failure of the heart's actual pumping capacity--it can't get blood out. Causes include idiopathic dilated cardiomyopathy, or myocardial infarctions that damage the muscle.

CHF secondary to diastolic dysfunction is the result of an impairment in heart's ability to relax. There is an increase in the ventricular diastolic pressure at any given diastolic volume. The heart doesn't let blood in well. Causes include restrictive and hypertrophic cardiomyopathies, ischemic states, hypertension, and senile cardiac amyloid.

Why is it important?

We currently know much more about systolic dysfunction than diastolic dysfunction in terms of treatment, but drugs may differ. Unfortunately, there are currently no data from prospective, randomized, blinded drug trials to guide treatment (Kitzman, 2002). Control of hypertension and minimizing ischemia are important goals. ACE inhibitors and Angiotensin Receptor Blocking agents appear to be indicated for both. While digoxin might be considered in systolic dysfunction, mainly now when there is atrial fibrillation, it may not be as effective in diastolic dysfunction because it increases contractility rather than relaxation. However, some data suggest that it may improve symptoms (Kitzman, 2002). Beta blockers also may be indicated in diastolic dysfunction. Thus in general, much more research is needed in this area to identify the best pharmacotherapeutic approach. However, it is also important to keep in mind that with diastolic dysfunction, venous return and adequate ventricular filling are very important to maintaining cardiac output. Thus there is a fine balance between giving diuretics to minimize symptoms and over-dehydrating the patient which can cause further cardiac dysfunction.