Ryo Tanaka, Presenter: Nothing to Disclose

Tomoharu Nakamura, Abstract Co-Author: Nothing to Disclose

Satoru Chiba, Abstract Co-Author: Nothing to Disclose

Akimichi Saito, Abstract Co-Author: Nothing to Disclose

Junichi Yamazaki, Abstract Co-Author: Nothing to Disclose

To evaluate reverse redistribution on 99m-sestamibi (MIBI) in atrioventricular (AV) block patients wearing pacemakers.

Fifteen patients with AV block, who have been controlled by permanent pacemakers (PPM), were included in the study. Myocardial perfusion was evaluated by early MIBI images, and reverse redistribution of MIBI was assessed based on the images from the late phase. The resulting myocardial SPECT was divided into 17 segments and visually assessed in four grades, from 0 (normal) to 3 (defective), to calculate defect score (DS). We also verified by CAG that there was no abnormal stenosis of coronary artery in all of the patients. Furthermore, to evaluate microcirculatory disorder, deceleration time of diastoric flow velocity (DDT) was calculated with the use of flow wire in defect area of MIBI delayed SPECT.

The mean DS was 3.07±0.95 in MIBI early SPECT, 9.33±1.78 in MIBI delayed SPECT, 2.27±2.17 in BMIPP SPECT, respectively. Therefore, a significant difference was observed between MIBI early SPECT and MIBI delayed SPECT, and between MIBI delayed SPECT and BMIPP SPECT (P < 0.0001). In addition, the value of DDT was low at 554 ± 344 m/sec. Therefore, correlation between the DS of MIBI delayed SPECT and DDT were observed with γ=0.61(P < 0.005). However, no significant correlation was observed between the DS of MIBI early SPECT and DDT, DS of BMIPP SPECT and DDT (ns).

In AV block patients who have been controlled by PPM for a long time, low value DDT was seen in cases showing strong reverse redistribution of MIBI. These abnormal findings may be associated with microcirculatory disorder. Thus, the reverse redistribution phenomenon on MIBI is considered useful for assessing PPM control.

SESTAMIBI reverse redistribution can demonstrate eloquent abnormal areas and is recommended in the initial evaluation microcirculatory disorder.

Tanaka, R, Nakamura, T, Chiba, S, Saito, A, Yamazaki, J, Effects of the Reverse Redistribution Phenomenon on 99m-sestamibi for Microcirculatory Disorder in Patients with AV Block.  Radiological Society of North America 2006 Scientific Assembly and Annual Meeting, November 26 - December 1, 2006 ,Chicago IL. http://archive.rsna.org/2006/4434913.html