Diastolic dysfunction refers to impaired relaxation and filling of the left ventricle during diastole (the phase between heartbeats). Instead of relaxing fully to accommodate incoming blood, the ventricle becomes stiff, raising filling pressures and causing blood to back up into the pulmonary circulation. The result is the symptoms of [heart failure](/glossary/heart-failure/) despite the heart continuing to pump a normal percentage of blood with each beat.
Diastolic dysfunction underlies [heart failure with preserved ejection fraction (HFpEF)](/glossary/heart-failure-with-preserved-ejection-fraction/). It exists on a spectrum from mild impairment detectable only on detailed echocardiographic Doppler assessment, through to severe dysfunction causing significant breathlessness and fluid overload.
Common causes include ageing, [hypertension](/glossary/hypertension/) (which causes the heart muscle to thicken and stiffen), diabetes, obesity, and coronary artery disease. Diastolic dysfunction is increasingly prevalent as the population ages and rates of metabolic conditions rise.
Diagnosis is made by [echocardiogram](/glossary/echocardiogram/) using Doppler measurements of ventricular filling patterns, alongside assessment of symptoms and [NT-proBNP](/glossary/nt-probnp/) levels. Management focuses on controlling contributing conditions (blood pressure, atrial fibrillation, fluid overload), symptom relief with diuretics, and lifestyle measures. SGLT2 inhibitors have demonstrated benefit in HFpEF clinical trials and are increasingly prescribed.
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