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Background: Because of difficulties with suture placement during minimally invasive procedures, many have sought alternative methods of creating tissue anastomoses. Although well studied, thermal laser tissue bonding has the potential of causing collateral thermal injury. Non-thermal tissue bonding agents, which cross-link proteins when activated with light, are currently being explored. We recently reported successful non-thermal bonding using tetrabromorhodamine (TBR). The bond was stronger than sutured repairs but weaker than laser thermal bonding. We currently report our ex-vivo experience with an alternate agent, riboflavin-5-phosphate and compare these results to thermal bonding and TBR.
Methods: Rabbit ureteral segments were harvested, divided and placed over internal stents. End-to-end anastomoses were created using several methods: 1)Photochemical bonding: The activating light source used was an Argon laser at a radiant exposure of 90 J/cm2. The photoalkylating agents used were TBR combined with collagen (n=15) or riboflavin combined with fibrinogen (n=12). 2)Thermal laser bonding: (n=12) 50% albumin and indocyanine green solder irradiated with the Diomed diode laser (Diomed Corp) at a radiation exposure of 119.4-597 J/cm2. 3)Sutured anastomoses: This was performed with 7-0 Dexon interrupted sutures. Control experiments using fibrinogen alone, TBR alone, riboflavin alone and collagen alone were also performed. Bond strength was evaluated by measuring the anastomotic leak pressure against a column of water.
Results: Thermal and photochemical bonding with both TBR and riboflavin were significantly stronger than sutured repairs. The bonds created wtih TBR (74±49 cmH2O) were weaker than those created by thermal welding (132±50cmH2O) and riboflavin (115±64cmH2O). ALP measurements in the control experiments were below 10 cmH2O.
Conclusion: Photochemical bonding with riboflavin can achieve similar bond strength to thermal welding without the risk of damage to surrounding tissues. We are currently evaluating in vivo efficacy of this modality. This alternative method of tissue bonding for minimally invasive procedures should be further explored.
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