Abstract:

BACKGROUND: For patients with myocardial infarction occupied most of the heart, the effect of coronary artery bridge is not obvious. Currently, myocardial and vascular regeneration by stem cells has become a focus of ischemic cardiovascular disease. Myocardial survival directly correlates with improvement of blood perfusion following stem cell transplantation.

OBJECTIVE: To investigate the feasibility of ¹⁸F-FDG and ⁹⁹Tc^m-MIBI single photon emission computed tomography imaging in assessing myocardial glucose metabolism and perfusion with old myocardial infarction after coronary artery bypass grafting (CABG) and CD34⁺ stem cell transplanting.

METHODS: Bone marrow was extracted from the anterior superior iliac spine 1 day before surgery. Mononuclear cells were isolated by Ficoll density gradient centrifugation. CD34⁺ cells were isolated and purified by immunomagnetic bead system. Coronary artery pathological changes were examined under general anesthesia. The end-to-side anastomosis of graft vessel and coronary artery was performed. 1×10¹¹/L CD34⁺ cell suspension was extracted, and injected into the surrounding and center of the infarct (blood flow/metabolism matching depletion) at 6 points, with 0.2 mL in each point. According to preoperative perfusion/metabolism imaging, myocardium segments were divided into two groups: match group: blood perfusion and metabolism images were sparse or normal, i.e. infarction or normal myocardium; mismatch group: blood perfusion image displayed depletion, but metabolism images were normal or radially distributed, i.e. surviving myocardium. ¹⁸F-FDG and ⁹⁹Tc^m-MIBI dual-isotopic imaging were performed before and 4 months after CABG. Circumferential count profiles from ¹⁸F-FDG and ⁹⁹Tc^m-MIBI short axis slices were generated to assess myocardial blood perfusion and glucose metabolism.

RESULTS AND CONCLUSION: The 31 patients were divided into 279 segments, and 145 segments were in myocardial perfusion–metabolism mismatch (MM). ⁹⁹Tc^m–MIBI and 18F-FDG uptake fraction was significantly increased 4 months before operation (P < 0.01); match group without transplanting had 81 segments, and the ⁹⁹Tc^m–MIBI and ¹⁸F-FDG uptake fraction remained unchanged after operation (P > 0.05). Match group undergoing transplanting had 54 segments, and their ⁹⁹Tc^m–MIBI and ¹⁸F-FDG uptake fraction increased remarkably 4 months after operation (P < 0.01). CABG can improve the function of survival myocardial segments, but it is helpless to infraction myocardium. The autologous CD34+ stem cell transplantation can improve myocardial blood perfusion and glucose metabolism of the distributions of infract myocardium.