Diastolic dysfunction is the hallmark of diabetic cardiomyopathy and echocardi-ography is invariably the most commonly employed test at the present time to reliably assess diastolic functional abnormalities. Left ventricular diastolic filling abnormalities in patients with diabetes do not correlate with the duration of diabetes nor with the presence of other complications such as retinopathy, nephropathy, or peripheral neuropathy. In diabetic cardiomyopathy, the initial abnormality of diastolic filling is characterized by a slowed or impaired myocardial relaxation as is the case for most other cardiac diseases. It should be noted that there is a gradual impairment of myocardial relaxation with normal aging, but in pathological states it is more pronounced than what is usually expected for the patient's age. With continued progression of the disease, LV compliance is reduced and elevation in left atrial pressure results in a restrictive LV filling pattern, which initially may be reversible, but eventually becomes fixed. Based on the pulsed-wave spectral Doppler flow patterns measured at the mitral valve tips, as well as at the entrance of the pulmonary veins into the left atrium, the spectrum of diastolic abnormality has been generally classified into four stages as discussed below.
1. Impaired Relaxation Pattern—Grade 1
In this stage of the disease, the mitral inflow Doppler pattern is characterized by prolonged isovolumic relaxation time (>90 ms), prolonged deceleration time (>240 ms), and reversal of the E and the A wave ratio (E/A <1) for patients in sinus rhythm. The systolic flow velocity at the pulmonary vein location is more prominent compared to the diastolic flow.
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