Diagnosis of diastolic dysfunction or diastolic heart failure remains imprecise. This has made it difficult to conduct clinical trials of treatments for diastolic heart failure. In some studies, diastolic dysfunction has been defined as heart failure with normal systolic function. That is, a patient is defined as having diastolic dysfunction if they have signs and symptoms of heart failure but the left ventricular ejection fraction is normal. A second approach is to use an elevated BNP level in the presence of normal EF to diagnose diastolic heart failure. These are both probably too broad a definition for diastolic heart failure and this group of patients is more precisely described as heart failure with normal systolic function. Echocardiography can be used to diagnose diastolic dysfunction. However, no one single echocardiographic parameter can make the diagnosis of diastolic heart failure. Multiple echo parameters have been proposed including mitral inflow velocity patterns, pulmonary vein flow patterns, tissue Doppler measurements, and M-mode echo measurements (ie. left atrial size). Algorithms have been developed which combine multiple echocardiographic parameters to diagnose diastolic heart failure.
There are four basic Echocardiographic patterns of diastolic heart failure, graded I to IV. The mildest form is called an abnormal relaxation pattern or grade I diastolic dysfunction. On the mitral inflow Doppler echocardiogram, there is reversal of the normal E/A ratio. This pattern may develop normally with age in some patients and many grade I patients will not have any clinical signs or symptoms of heart failure.
Grade II diastolic dysfunction is called pseudonormal filling dynamics. This is considered moderate diastolic dysfunction and is associated with elevated left atrial filling pressures. These patients more commonly have symptoms of heart failure and many have left atrial enlargement due to the elevated pressures in the left heart.
Grade III and IV diastolic dysfunction are called restrictive filling dynamics. These are both severe forms of diastolic dysfunction and patients tend to have advanced heart failure symptoms. Class III diastolic dysfunction patients will demonstrate reversal of their diastolic abnormalities on echocardiogram when they perform the Valsalva maneuver and are called reversible restrictive diastolic dysfunction.
Class IV diastolic dysfunction patients will not demonstrate reversibility of their echocardiogram abnormalities and are therefore called fixed restrictive diastolic dysfunction. The presence of either class III and IV diastolic dysfunction is associated with a significantly worse prognosis. These patients will have left atrial enlargement and many will have a reduced left ventricular ejection fraction indicating a combination of systolic and diastolic dysfunction.
Volumetric definition of systolic heart performance is commonly accepted as ejection fraction. Volumetric definition of the heart in systole was first described by Adolph Fick as cardiac output. Fick may be readily and inexpensively inverted to cardiac input and injection fraction to mathematically describe diastole. Decline of Injection fraction paired with decline of E/A ratio seems a stronger argument in support of mathematical definition of diastolic heart failure.
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