Abstract:

BACKGROUND: Many experiments have suggested that transmyocardial revascularization (TMR) is effective in refractory angina pectoris and end-stage coronary artery disease. The main problem for TMR, however, is occlusion of the transmural channels, which limits the application of the technology.
OBJECTIVE: To explore the impact of transmyocardial high-pressure injection revascularization combined with thermo-sensitive chitosan hydrogel filled the channels on channel’s patency and the effect of promoting angiogenesis and myocardial protection on acute myocardial infarction.
METHODS: High-pressure injection system, Injex needle-free syringe was made by the appropriate transformation of post-production. Thermo-sensitive chitosan hydrogel was made of chitosan hydrochloride, β-glycerol phosphate and hydroxyethyl cellulose prepared in accordance with a certain concentration ratio. A total of 24 healthy hybrid dogs were randomly assigned to three groups. In the simple myocardial infarction group (SMI), acute myocardital infarction models were made by ligation of the left anterior descending coronary artery. No treatment was given in SMI group. In the transmyocardial high-pressure injection revascularization group (TMIR) with thermo-sensitive chitosan hydrogel group (TMIR+chitosan), transmyocardial high-pressure injection revascularization was performed on infarct myocardium and about 8 to 10 transmural channels were created in ischemic area, one channel per square centimeter. In the TMIR group, the same volume saline was used in the identical site. Hemodynamics, capillary density and myocardial infarct size were detected at 6 weeks after treatment. Hematoxylin and eosin staining and Sirius red staining were used to detect channel patency and collagenous fiber proliferation, and the ratio of type Ⅰ, Ⅲ collagen was calculated. 
RESULTS AND CONCLUSION: The channels in TMIR group had significantly narrowed; some segments had been completely occluded. However, channels in TMIR + chitosan group had not been occluded, the opening diameter was about 100-300 μm; some segments had been endothelialization. Compared with the SMI group, TMIR group and TMIR + chitosan group promoted angiogenesis in the infarct area, and TMIR + chitosan group reduced the infarct size and improved left ventricular remodeling. These indicated that transmyocardial high-pressure injection revascularization combined with thermo-sensitive chitosan hydrogel filled the channels is helpful to maintain the channel patency and can promote angiogenesis around the channels, reduce infarct size and improve left ventricular remodeling. It may be a viable approach in the treatment of myocardial infarction.