Selected Technique Application of Shape Memory Alloy Pressure-Controlled Vascular Clamp for Atraumatic Vessel Occlusion Ye Zhang, 1 Yun Luo, 1 Shingo Kodaira, 2 and Toshiyuki Takagi, 2 Sendai, Japan Background: To realize atraumatic vessel occlusion, a new hemostatic clamp using superelas- tic shape memory alloy (SMA) as a pressure control limiter has been proposed. It was designed taking advantage of a unique mechanical property of SMA. The ability to control pressure with the newly designed SMA clamp was investigated. The traumatic effect on vessel walls was eval- uated in order to confirm the SMA clamp’s biological effect of protecting vessels from damage. Methods: Twenty-four pig thoracic aortas were divided into four groups: SMA group 1 (0.3 mm diameter SMA wire used), SMA group 2 (0.4 mm diameter SMA wire used), base model group (hemostatic clamp of Mimura type), and a control group. The biomechanical interaction between the pressure-controlled clamp and animal aortas was evaluated with a micropressure analyzing system. The atraumatic effect of the SMA clamp was examined on pig thoracic aortas in vitro and compared with that of its base model. The morphological injury of each vessel was evaluated after being clamped for 15 min. Results: Pressure saturation was shown in the displacementepressure curve of the SMA clamp. In both SMA group 1 and SMA group 2, except for a slight imprint of compression in the intima, no obvious injury was observed, while in the base model group the endothelial lacer- ation was observed when the clamp was closed to notch I. More serious injuries in the endothe- lial intima and media were observed when the clamp was closed to notches II and III. Conclusion: The effect of pressure-controlling SMA clamps on the in vitro vessel model was evaluated. Histological observation and the traumatic score proved that the safety of the clamps was improved with the new design of pressure control. This technique supplies an effective and applicable way of realizing atraumatic clamping. INTRODUCTION The clamp technique is essential in any surgical operation. 1 Clamps are used to arrest bleeding and to control blood flow from the arteries. They are also used to ensure a clear surgical view through temporary local vascular control in order to favor- ably accomplish operations. This is achieved by either cross- or lateral clamping. 2 However, clamps may also cause moderate to severe damage to the vessel wall. Injuries caused by incorrect use of clamps have been reported in several articles. 3,4 Coelh et al., 4 using arteriographic and ultrasonic evaluation, showed that the proportion of intimal tears and flaps will reach 26% in some cases. Atraumatic technique is an important issue in surgery. Since Guthrie suggested its importance in 1903, many kinds of atraumatic clamps, such as Sat- insky and De Bakey, have been invented. 5 Although these clamps have been widely used, they could not fully meet the demand of the atraumatic technique. Dujovny et al. 6 demonstrated that these ‘‘atrau- matic clamps’’ may also cause considerable endo- thelial damage, which is proportional to the ‘‘closure force’’ applied. Injuries of vessels could be minimized when force was controlled by closing to 1 Biomedical Engineering Research Organization, Tohoku Univer- sity, 2-1 Seiryo, Aoba, Sendai 980-8575, Japan. 2 Institute of Fluid Science, Tohoku University, 2-2-1 Katahira, Aoba, Sendai 980-8577, Japan. Correspondence to: Ye Zhang, MD, Biomedical Engineering Research Organization, Tohoku University, 2-1 Seiryo, Aoba, Sendai 980-8575, Japan, E-mail: [email protected]Ann Vasc Surg 2009; 23: 813-820 DOI: 10.1016/j.avsg.2009.06.001 Ó Annals of Vascular Surgery Inc. Published online: September 11, 2009 813
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Selected Technique
1Biomedicasity, 2-1 Seiryo
2InstituteAoba, Sendai
CorrespondResearch Orga980-8575, Jap
Ann Vasc SurgDOI: 10.1016/� Annals of VPublished onli
Application of Shape Memory AlloyPressure-Controlled Vascular Clampfor Atraumatic Vessel Occlusion
Ye Zhang,1 Yun Luo,1 Shingo Kodaira,2 and Toshiyuki Takagi,2 Sendai, Japan
Background: To realize atraumatic vessel occlusion, a new hemostatic clamp using superelas-tic shape memory alloy (SMA) as a pressure control limiter has been proposed. It was designedtaking advantage of a unique mechanical property of SMA. The ability to control pressure withthe newly designed SMA clamp was investigated. The traumatic effect on vessel walls was eval-uated in order to confirm the SMA clamp’s biological effect of protecting vessels from damage.Methods: Twenty-four pig thoracic aortas were divided into four groups: SMA group 1 (0.3 mmdiameter SMA wire used), SMA group 2 (0.4 mm diameter SMA wire used), base model group(hemostatic clamp of Mimura type), and a control group. The biomechanical interaction betweenthe pressure-controlled clamp and animal aortas was evaluated with a micropressure analyzingsystem. The atraumatic effect of the SMA clamp was examined on pig thoracic aortas in vitro andcompared with that of its base model. The morphological injury of each vessel was evaluatedafter being clamped for 15 min.Results: Pressure saturation was shown in the displacementepressure curve of the SMAclamp. In both SMA group 1 and SMA group 2, except for a slight imprint of compression inthe intima, no obvious injury was observed, while in the base model group the endothelial lacer-ation was observed when the clamp was closed to notch I. More serious injuries in the endothe-lial intima and media were observed when the clamp was closed to notches II and III.Conclusion: The effect of pressure-controlling SMA clamps on the in vitro vessel model wasevaluated. Histological observation and the traumatic score proved that the safety of the clampswas improved with the new design of pressure control. This technique supplies an effective andapplicable way of realizing atraumatic clamping.
INTRODUCTION
The clamp technique is essential in any surgical
operation.1 Clamps are used to arrest bleeding and
to control blood flow from the arteries. They are
also used to ensure a clear surgical view through
temporary local vascular control in order to favor-
ably accomplish operations. This is achieved by
l Engineering Research Organization, Tohoku Univer-, Aoba, Sendai 980-8575, Japan.
of Fluid Science, Tohoku University, 2-2-1 Katahira,980-8577, Japan.
ence to: Ye Zhang, MD, Biomedical Engineeringnization, Tohoku University, 2-1 Seiryo, Aoba, Sendaian, E-mail: [email protected]
2009; 23: 813-820j.avsg.2009.06.001ascular Surgery Inc.ne: September 11, 2009
either cross- or lateral clamping.2 However, clamps
may also cause moderate to severe damage to the
vessel wall. Injuries caused by incorrect use of
clamps have been reported in several articles.3,4
Coelh et al.,4 using arteriographic and ultrasonic
evaluation, showed that the proportion of intimal
tears and flaps will reach 26% in some cases.
Atraumatic technique is an important issue in
surgery. Since Guthrie suggested its importance in
1903, many kinds of atraumatic clamps, such as Sat-
insky and De Bakey, have been invented.5 Although
these clamps have been widely used, they could not
fully meet the demand of the atraumatic technique.
Dujovny et al.6 demonstrated that these ‘‘atrau-
matic clamps’’ may also cause considerable endo-
thelial damage, which is proportional to the
‘‘closure force’’ applied. Injuries of vessels could be