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Diastolic heart failure (HF) has emerged over the last two decades as a separate clinical entity. Approximately half of the patients presenting with symptoms of congestive HF exhibit a near normal left ventricular (LV) systolic function at rest, which is thought to be caused by a predominant abnormality in diastolic function. It is generally considered to have a somewhat better prognosis than systolic HF, but frequency of hospitalisations is comparable in systolic and diastolic HF.1 Prevalence of diastolic HF increases with age and is higher in women. It is associated with hypertension, hypertrophy, diabetes, ageing and ischaemia.2 Despite the recognition of its importance, definition and diagnostic criteria of diastolic dysfunction and diastolic HF remain controversial.
The cardiac cycle encompasses systole and diastole. Regardless of the exact time limits of these periods, it is generally accepted that systolic function relates with the ability of the ventricle to contract and eject, while diastolic function reflects its ability to relax and fill. Diastolic dysfunction therefore refers to a disturbance in ventricular relaxation, distensibility or filling—regardless of whether the ejection fraction (EF) is normal or depressed and whether the patient is asymptomatic or symptomatic.3 If a patient, with preserved EF and diastolic dysfunction, exhibits symptoms of effort intolerance and dyspnoea, especially if there were evidence of venous congestion and oedema, the term diastolic HF is used.4
PHYSIOLOGY OF DIASTOLIC FUNCTION
Determinants of diastolic function (table 1) include myocardial relaxation and passive properties of the ventricular wall, such as myocardial stiffness, wall thickness and chamber geometry (size or volume). Other determinants include the structures surrounding the ventricle, the left atrium, pulmonary veins and mitral valve, and heart rate. Except for heart rate these other determinants are extrinsic to the ventricle and therefore normally not considered as true causes of ventricular diastolic dysfunction or failure. Moreover, …