The impact of segmental volumetric changes on functional mitral regurgitation: a study using three-dimensional regional time-volume analysis combined with low-dose dobutamine.

PURPOSE

Using transthoracic three-dimensional (3D) echo regional volume analysis combined with low-dose dobutamine to investigate the effects on regional volume, mitral configuration and functional mitral regurgitation (FMR).

METHODS

Fifty-six patients with ischemic cardiomyopathy (ICM) were included in this study. The effective regurgitant orifice area (EROA) of FMR secondary to ICM with depressed left ventricular ejection fraction was compared with mitral tenting area and coaptation height (CH) before and after low-dose dobutamine (10 μg/kg per min). Using 3-DQ software we measured and calculated regional stroke-volumes (rSV), the ratio of the rSV to the whole left ventricular stroke volume (rgSVratio) in all 17 segments and the average rgSVratio of 4 anterior-PM attached segments (rgSVratio-aver anter-PM), 4 posterior-PM attached segments (rgSVratio-aver post-PM), 8 PMs attached segments (rgSVratio-aver PMs) and all 17 segments before and after dobutamine.

RESULTS

Compared with the resting condition, the SVr and rgSVratio on the basal and mid segments of anterior, lateral, inferior, and posterior walls were increased after dobutamine infusion (P < 0.05). EROA at rest was associated with tenting area, CH and rgSVratio-aver of PMs and the reduction in EROA caused by dobutamine was associated with reductions in tenting area, CH and increases in rgSVratio-aver of PMs. Tenting area was associated with rgSVratio-aver of PMs and reduction caused by dobutamine was associated with increases in rgSVratio-aver of PMs.

CONCLUSIONS

The FMR decreasing during low-dose dobutamine is quantitatively associated with the regional LV volume change of attached PMs. Real time transthoracic three-dimensional echocardiography may provide a simple and noninvasive approach to assess regional LV time-volume characteristic during FMR.