Introduction. The mechanism by which transmyocardial revascularization (TMR) exerts a beneficial effect remains unknown. This thesis hypothesizes that myocardial punctures for TMR cause a myocardial injury, leading to an angiogenic response mediated by a number of growth factors. / Methods. Fifty-three rats underwent ligation of the left coronary artery. Group I (n = 25) served as controls, while Group II (n = 28) underwent concomitant TMR by creating six transmural channels with a 25-gauge needle in the ischemic zone. Surviving animals in both groups were sacrificed at intervals of 1, 2, 4, and 8 weeks (n = 5 in each subgroup). Immunohistochemistry in the infarct areas was performed for factor VIII to assess vascular density. Immunohisto-chemistry using specific antibodies was also performed for transforming growth factor-beta (TGFbeta), basic-fibroblast growth factor (b-FGF), and vasoendothelial growth factor (VEGF). Growth factor expression was quantitated by comparing areas of staining (in mm2) using computerized morphometric analysis. / Results. Mortality was similar in both groups (5/25 vs. 8/28, p = NS). Group II had significantly greater vascular density than Group I (5.65 vs. 4.06 vessels/HPF, p < 0.001), with a peak at 1 week post-operatively (9.12 vs. 5.56 vessels/HPF, p < 0.0001) in both groups. Overall, both TGFbeta and bFGF were significantly higher in the TMR group compared to the control group (0.207 mm2/mm2 vs. 0.141 mm2/mm 2, p < 0.05 and 0.125 mm2/mm2 vs. 0.099 mm2/mm2, p < 0.05). / Conclusions. This model of TMR is associated with a significant angiogenic response, which appears to be mediated by the release of certain angiogenic growth factors such as TGFbeta and bFGF. With the long term patency of laser-created myocardial channels in clinical TMR increasingly in doubt, its mechanism of myocardial revascularization may be similar to that observed in our model.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.30723 |
| Date | January 2000 |
| Creators | Pelletier, Marc P. |
| Contributors | Chiu, Ray C.-J. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Division of Surgical Research.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001754441, proquestno: MQ64428, Theses scanned by UMI/ProQuest. |
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