DIASTOLIC DYSFUNCTION

Diastolic dysfunction is a type of heart failure where there is increased filling pressures in the ventricle due to increased stiffness or thickness of the ventricular wall.  The diagnosis of diastolic dysfunction is now being applied to more and more patients, mainly women.

Hypertension is a leading cause of diastolic dysfunction.  Other causes can include volume overload, tachycardia, exercise, ischemia, systemic stressors ( infection, fever, etc.), arrhythmias, increased salt intake and use of NSAIDS.  Actually about 40% patients with heart failure actually have preserved systolic function and thus have a normal ejection fraction.  The incidence of diastolic heart failure increases with age, and it is more common in older women.  The mortality rate is 50% lower for patients with stable diastolic dysfunction than for those with stable systolic dysfunction.

The part of the cardiac cycle where there is filling of the ventricle is called diastole.  Sometimes, due to various medical conditions, the ventricles become stiff and cannot fully relax during diastole, and therefore cannot fill completely.  Blood then can back up usually in the lungs.

Diagnosis of diastolic dysfunction is not as straightforward as the diagnosis of systolic dysfunction.  Patients with diastolic dysfunction usually have a normal ejection fraction.  Many symptoms of heart failure such as fatigue, dyspnea on exertion, orthopnea, paroxysmal nocturnal dyspnea, edema, JVD, and rales  often occur in noncardiac conditions  The use of the blood test for BNP can accurately differentiate heart failure from noncardiac conditions, but it cannot distinguish diastolic dysfunction from systolic dysfunction.  Cardiac catheterization remains the preferred method for diagnosing diastolic dysfunction.

Early diagnosis and treatment is important in preventing irreversible structural alterations and systolic dysfunction.  Medical therapies for diastolic dysfunction often are empirical and not as well defined as therapies for systolic dysfunction.  The treatment of diastolic dysfunction is limited by the lack of trials for medications for pure diastolic dysfunction.  Actually the treatment for systolic dysfunction may exacerbate diastolic dysfunction.

Recommendations for treating diastolic dysfunction include having the physician address blood pressure control, heart rate control, central blood volume reduction, and alleviation of myocardial ischemia.

Controlling heart rate maximizes the diastolic filling period.  Beta blockers are useful for this purpose.

The use of ACE Inhibitors helps reduce cardiac preload and afterload.  Indirect benefits of decreasing preload and afterload include improving left ventricular filling and reducing blood pressure.  With this there is an improvement in exercise capacity and quality of life.

Other drug therapy for diastolic dysfunction may include the use of diuretics if there is the presence of fluid overload.  Calcium channel blockers have also been shown to improve diastolic function.  Aslo vasodilators may be useful because of their preload reducing and anti-ischemic effects; especially when an ACE Inhibitor cannot be used.

Use of vasodilators should be used with caution as decreasing preload may worsen cardiac output.  There are no studies that show a significant survival benefit in patients with the use of vasodilators.

*Information for the above page comes from American Family Physician, March 1, 2006.