Principles of Microvascular Surgery.

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Antithrombotic therapy Tissue plasminogen activator (tPA) • Produced by human vascular endothelium. • Activates plasminogen (inactive precursor to plasmin). • Levy, J Reconst Microsurg 1991 - no difference between tPA and urokinase in the rat model. • Others report cases of free flap salvage with tPA infusion - Fedem & Walton, J Reconst Microsurg 1989. Arnljots, PRS 1992. Romano, 1991. • Reports on selective tPA infusion. Antithrombotic therapy • Davies, Br J Plast Surg 1982 - surveyed the use of anticoagulation in clinical microsurgery. » 73 centers in 22 countries. » Found equal success rates (89%) for free flaps with anticoagulation (n=691) and flaps without anticoagulation (n=134). » For limb replantation - success rat was lower with anticoagulation (76%) than without (89%). 20
Antithrombotic therapy conclusions: • No definite indications when mechanical and vascular factors are optimal. • When there is thrombosis in the post operative period - flap reexploration and treatment with fibrinolytic and/or anticoagulation therapy. • Anticoagulation or fibrinolytic therapy may be indicated where mechanical or metabolic factors are not favorable and cannot be improved. Tissue response to ischemia and hypoxia • Free tissue transfer requires a period of tolerance to ischemia by the donor tissue. • Skin and subcutis are relatively resistant to anoxia - » Intracellular pH changes - reversible up to 24h. • Mammalian skeletal muscle - » much less tolerance to ischemia. » Irreversible damage to energy metabolism - 4h. » Irreversible damage starts at 6 hours. • Connective tissue (fibroblast, chondroblast, osteoblast) relatively resistant to hypoxia. 21
Page 1 and 2: Principles of Microvascular Surgery
Page 3 and 4: History • Malt & McKhann, 1962 -
Page 5 and 6: History • Danil & Taylor + O’br
Page 7 and 8: Basic Science Concepts in Microsurg
Page 9 and 10: Vessel Injury and Regeneration •
Page 11 and 12: Vessel Wall Healing • At the time
Page 13 and 14: Damage from needles, sutures and te
Page 15 and 16: The clotting mechanism • Platelet
Page 17 and 18: Antithrombotic therapy Heparin (con
Page 19: Antithrombotic therapy Low molecula
Page 23 and 24: The no-reflow effect • Ames, Am J
Page 25 and 26: • Treatment - The no-reflow effec
Page 27 and 28: • Loupes… • Or microscope? Mi
Page 29 and 30: • Key sutures - Anastomotic techn
Page 31 and 32: End-to-end, end-to-side and end-in-
Page 33 and 34: Laser anastomosis • Various exper
Page 35 and 36: Monitoring perfusion • Doppler ul
Page 37 and 38: The influence of patient factors
Page 39 and 40: Free flaps • Twenty years ago - f
Page 41 and 42: • Free groin flap - Free flaps -
Page 43 and 44: Free flaps - fascia • Useful wher
Page 45 and 46: Free flaps - muscle • Free latiss
Page 47 and 48: Free fibula flap 47

Principles of Microvascular Surgery.

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