MR Flow Mapping of Dobutamine-Induced Changes in Diastolic Heart Function

Abstract

Purpose: To evaluate the ability of MR flow mapping to measure changes in left ventricular filling during β-adrenergic stimulation. Materials and Methods: Mitral flow was measured in 10 healthy volunteers using conventional free breathing fast-field echo (FFE) with a spatial resolution of 2.7 × 2.2 mm and a temporal resolution of 22 msec. The sequence was repeated during dobutamine infusion (20 μg/kg/minute). Results: Stroke volume increased from a median of 99 mL (range: 68-142 mL) (Note: values as presented are medians and ranges, throughout) to 114 mL (87-180 mL) (P < 0.05). Both early (E) peak filling rate (554 mL/second [433-497 mL] to 651 mL/second [496-1096 mL/second]) (P < 0.05) and atrial (A) peak filling rate (238 mL/second [183-352 mL/second] to 341 mL/second [230-538 mL/second]) (P < 0.05) increased. These changes, together with the increase in E acceleration peak and A deceleration peak, were consistent with facilitated myocardial relaxation. Conclusion: Conventional free breathing FFE has the ability to measure the effects of β-adrenergic stimulation on left ventricular filling.