In vivo thermography during small bowel fusion using radiofrequency energy

Abstract

Hypothesis: Radiofrequency controlled tissue fusion has minimal lateral thermal damage.Design: Experimental study. Setting: Live animal laboratory.Subject: One female pig weighing approximately 100kg.Intervention: Evaluate lateral thermal spread in in vivo and ex vivo bowel fused by radiofrequency energy using dynamic infrared thermography and histology. Results:Mean maximum thermal spread measured on histology was less than 1.2 mm, with no significant difference between thermal spreads for in vivo and ex vivo bowel for radiofrequency energy delivered at 50 V (p = 0.98) and 100 V (p = 0.85). Mean total maximum thermal spread measured by dynamic infrared thermography was less than 3.9 mm on both sides of the instrument with no significant difference between thermal spreads for in vivo and ex vivo bowel for radiofrequency energy delivered at 50 V (p = 0.34) and 100 V (p = 0.19). Fusion quality for in vivo tissue was better when radiofrequency energy was delivered at 100 V rather than 50 V. However, thermal spread measurements and maximum temperatures reached in the tissue were similar in well and poorly fused bowel. Thermal changes in well-fused bowel were more uniform throughout the different bowel wall layers whereas in poorly fused tissues, the mucosa did not show thermally-induced changes. There were no significant differences between the maximum temperatures detected for in vivo and ex vivo bowel for radiofrequency energy delivered at 50 V (p = 0.25) and 100 V (p = 0.14). Conclusions:The total thermal changes at both sides of fused bowel are less than 3.9mm.The heat sink effect of the application instrument overshadowed any effects of perfusion on

Development of a Simultaneous Cryo-Anchoring and Radiofrequency Ablation Catheter for Percutaneous Treatment of Mitral Valve Prolapse

“…Previous studies have used IR imaging to identify the lethal isotherm of RF lesions. 27,44 Leaflets were imaged in a custom built bath, and the camera was placed below the bath for imaging of full thickness changes in temperature distribution (Fig. 8B).…”

Preliminary study of a control algorithm for radio-frequency-induced intestinal tissue fusion

“…The small intestine tissue contains a certain amount of collagen [13], which makes it possible to fuze the digestive tract tissue through RF energy. The factors that affect the tissue burst pressure, such as the compression pressure, fusion temperature, and fusion time, have been studied previously [6,[15][16][17][18]. However, studies are lacking regarding the optimization of the control algorithm based on RF energy to improve the tissue fusion effect.…”

“…The grayscale represents the difference in temperature. The critical temperature above which tangible heat damage can occur to tissue is assumed to be 45 C ( Figure 6(b)) [17,21,22]. Thermal damage range is then calculated by measuring the maximum distance between the 45 C contours (L1 in Figure 6(c)) on the planar projection and then subtracting fusion equipment jaw diameter (L2 in Figure 6(c)) to get the total thermal damage range.…”

“…Under the vessel sealing mechanism based on the RF energy, the collagen in the vessel forms a new hinge to achieve the effect of vessel sealing [7][8][9][10][11][12]. Because the small intestine tissue contains a certain amount of collagen [13], some scholars suspect that the tissue can be fused by RF energy [6,[14][15][16][17][18]. If this method is successful, it would have significant advantages over the traditional manual suture and stapler anastomosis methods.…”

Design of a factorial experiment with randomization restrictions to assess medical device performance on vascular tissue

“…Histopathology is commonly used to estimate the extent and degree of thermally-induced coagulative necrosis and protein denaturation incurred in relation to the distance from the point of energy application [14]. However, measurements of tissue injury margins obtained by histopathology may not reflect the true distance of thermal impact due to the tissue shrinkage that occurs during processing [15]. Several methods exist for determining temperature elevation and thermal spread in tissues at and at fixed distances from the energy source [16].…”