Radionuclide angiographic evaluation of left ventricular diastolic function

Left ventricular diastolic function is altered in the majority of patients with cardiac diseases, especially those characterized by myocardial ischemia or hypertrophy. In many circumstances, such abnormalities related to impaired relaxation or reduced distensibility may precede evidence of left ventricular systolic dysfunction. Radionuclide angiography may be adapted to study the rapid filling phase of diastole, the duration of the isovolumic relaxation phase, the relative contributions of rapid filling and atrial systole to left ventricular stroke volume, and the relation between regional nonuniformity of left ventricular function and global filling properties. Technical aspects of data acquisition that must be considered for such studies include the effects of cardiac cycle length fluctuations, temporal resolution, temporal smoothing, and normalization parameters. As noninvasive radionuclide methods (and any other analyses using purely noninvasive techniques) do not permit assessment of the left atrial-left ventricular pressure gradient or the simultaneous evaluation of changes in left ventricular pressure and volume during relaxation and filling, complete clinical interpretation of 'abnormal' left ventricular filling indexes, or changes in these indexes after interventions, is not possible. Despite the inherent limitations of noninvasive assessment of left ventricular diastolic function, radionuclide evaluation of left ventricular filling may provide clinically useful insights, especially in patients with congestive heart failure symptoms and normal left ventricular systolic function.