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3. Restrictive Filling Pattern—Reversible Grade 3 and Irreversible Grade 4

This phase is characterized by shortened isovolumic relaxation time (<70 ms), markedly shortened deceleration time (<160 ms), and very prominent E wave resulting in a E- to A-wave ratio of greater than 2 on the mitral inflow Doppler spectra. On the pulmonary vein Doppler flow pattern, the diastolic flow is markedly prominent compared to the systolic flow component. With appropriate treatment, such as afterload reduction, the restrictive filling pattern may revert back to impaired relaxation pattern in the earlier stages (Grade 2) of the disease. But, with continued progression of the disease, the restrictive pattern becomes irreversible despite treatment (Grade 4). A restrictive filling pattern indicates poor prognosis and with medical management the return of an impaired relaxation pattern denotes an improvement in clinical outcome. Thus, in addition to its prognostic value, these parameters may also serve to assess the response to treatment.

As noted above, during the pseudonormal phase of the diastolic functional impairment, the mitral inflow Doppler pattern may erroneously appear normal to a simple visual assessment. However, a reduction in the preload by Valsalva maneuver usually unmasks the underlying impaired relaxation of the LV. Alternatively, administration of sublingual nitroglycerin achieves a comparable effect in those patients who cannot effectively perform a Valsalva maneuver. It should be noted that the pulmonary vein flow does continue to reflect the diastolic impairment even when the mitral flow pattern portrays a pseudonormal pattern. Employing this approach, recent studies have shown that diastolic abnormalities are much more common than previously reported in type 2 diabetic patients with otherwise good glycemic control who are free of clinically detectable heart disease (21). Thus, the value of a comprehensive Doppler assessment of the mitral tips and pulmonary veins flow patterns cannot be overemphasized.

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