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A Multicenter, Single-Arm Exploratory Trial Evaluating the Safety and Efficacy of BTM2 Subcutaneous Implantation and BTM2 Biotube-Based Arterial Bypassing to the Lower Extremity for Critically Ill Leg Ischemic Subjects.

Basic Information

Recruitment status	Recruiting
Health condition(s) or Problem(s) studied	Patients with critical limb ischemia in the absence of optimal autologous veins.
Date of first enrollment	21/11/2024
Target sample size	2
Countries of recruitment
Study type	Interventional
Intervention(s)	1) A subcutaneous pocket is created by dissecting the skin of the abdomen and peeling the dermal layer below. The number of BTM2 implanted per subject should be at least 2 and at most 4. 2) Insertion of the sizer in the fabricated subcutaneous pocket to ensure sufficient space for implantation. 3) Remove BTM2 aseptically from the packaging bag, and confirm that there is no deformation, abnormality, etc. 4) If subcutaneous hemorrhage occurs, complete hemostasis is achieved with an electrocautery, etc. 5) Rinse the subcutaneous pocket thoroughly with saline. 6) Fibrin Glue(Bolheal or Beriplast) or bloodspray on BTM2 are inserted and placed subcutaneously. 7) A break drain is inserted subcutaneously and fixed. 8) Intradermal sutures are made, and BTM2 is fixed and closed intradermally. 9) Aspiration of air in BTM2 is initiated through a break drain. 10) Two to 14 days after implantation, echography of the implant site and visual inspection confirm that the bleeding and exudate have subsided, and remove the break drain. The implant site will also be confirmed by echography approximately 1 week after removal of the break drain. Around BTM2 by echography Blood and exudate collections are removed by puncture. 11) BTM2 should remain stationary for 4 to 24 weeks after implantation (in principle, at least 8 weeks). 12) Repeat, the skin is dissected, and the subcutaneous tissue is dissected while hemostatic to remove BTM2. 13) After removing the connective tissue on the outer periphery of BTM2, the outer shell is removed, and the formed biotube is removed together with the middle core. 14) The biotube is withdrawn from the core and washed with physiological saline. 15) A linearized rod is inserted into the biotube lumen and immersed in alcohol (70%) for 30 minutes in an immersion dish. 16) Irrigate the biotube with isotonic sodium chloride solution again, and visually check that there is no significant deviation of breakage, defect, and thickness. 17) Store in heparinized saline until transplantation 18) As with bypass with an autologous vein graft, the biotube should be loaded with saline with a syringe to ensure no leak. Sample from both ends of the biotube selected for implantation and measure maximal strength using a tensile testing machine to ensure that the reference strength (8.33N) is met. Using the entire length of the biotube containing the part to be implanted just before implantation, pressure monitoring should be used to confirm pressure resistance (turgor and rupture in 200 mmHg pressure overload conditions). Biotubes fabricated by the procedures described above 1)-18) are implanted into the subject's lower extremity as an alternative vessel as well as an autologous vein graft.

Outcome(s)

Primary Outcome

Ability of biotubes to form by the test instrument (BTM2).

Secondary Outcome

1)Procedural success with respect to implantation and extraction of the test device. 2)Technical success of bypass surgery involving p eripheral anastomosis using biotubes formed by th e test instrument. 3)Patency of the biotube at 4weeks after implant ation. 4)Improvement of symptoms (improvement of isch emic pain, improvement of wounds) 5)Avoidance of major amputation. 6)Rates of additional treatment during implantation of the test device and after biotube implantation 7)QOL during test device implantation and after bi otube implantation. 8)Bypass graft diameter after bypass surgery.

Key inclusion & exclusion criteria

Age minimum	>= 18age old
Age maximum	Not applicable
Gender	Both
Include criteria	(1)Patients for whom written informed consent has been obtained from the individual regarding their p articipation in the clinical trial. (2)Patients aged 18 years or older at the time of inf ormed consent (3)Individuals with critical limb ischemia meeting is chemia (Ischemia)grade 2 or 3 (ABI <0.6, SPP <40 mmHg) in the Comprehensive Advanced Chronic L eg Ischemia (Chronic Limb Threatening Ischemia; CLTI) severity WIfI categorization (Ref. 15). (4)Among patients for whom lower extremity arteria l bypass is recommended, those who meet any of t he following: a.Global Vascular Guideline(GVG) GLASS(GlobalAnatomic Staging System) of (Ref. 8) the ischemic imb of stage III in the classification, which falls und er WIfI classification clinical stage 2, 3 or 4 Ischemic limb b.GLASS stage II that falls under WIfI class clinical stage 3 or 4Ischemic limb c.GLASS stage I or II that does no t achieve adequate blood flow despite endovascula r treatment (including clinical failure that does not l ead to healing of the wound and does not improve clinical condition) d.Ischemic limb after venous bypass that does not achieve adequate blood flow despite endovascular treatment (including clinical failure not leading to healing of the wound and improvement of clinical symptoms) (5)Patients who meet the length and diameter (3 m m or higher) required for bypassing surgery and wh o do not have an optimal upper or lower extremity vein (for patients with chronic kidney disease stage G5, for patients with lower extremity vein) without a bnormal findings such as varicocele, or who are ju dged to have no vein or difficult to harvest from a medical perspective based on the eligibility commit tee. (6)Patients requiring peripheral anastomosis of byp ass to the crural or pedal arteries below the knee. (7)Patients who are judged to be able to survive for at least 12 months and to be followed up for 12 we eks after bypass surgery at the time of informed co nsent.
Exclude criteria	(1)Patients with a general condition in which it is dif ficult to ensure the duration of implantation of the t est device required for biotube formation because of conditions requiring immediate revascularizatio n, etc. (2)Patients with general condition judged to be diffi cult to accept operative procedures due to severe undernutrition (CONUT score 8-12) (Ref. 19) or se vere complications, etc. (3)Patients who may not have two or more implant sites for the test device because of poor skin condit ion or history of exposure to subcutaneous implant s in the past. (4)Patients undergoing invasive surgical procedure s within 30 days before enrollment (excluding proc edures for foot wounds) (5)Patients with no target arteries on the peripheral side required for bypass surgery or a history of end ovascular treatment at the site of planned peripher al anastomosis (6)Occlusion of the artery proximal to the planned s ite of anastomosis on the central side of bypass su rgery Thromboendothelial removal during bypass surger y in the present study, By releasing the occlusion by artificial vascular byp ass Unavoidable patient. (7)Patients in whom blood circulation distal to the p lanned site of distal anastomosis of bypass surgery cannot be confirmed (excluding patients in whom c ollateral circulation can be confirmed) (8)Patients undergoing lower limb amputation proxi mal to the midfoot (9)Patients with a history or concomitant malignanc y (excluding those with no recurrence or no new on set for more than 5 years after treatment) (10)Patients receiving immunosuppressive drugs f or complications of autoimmune diseases or after tr ansplantation (11)Patients with a history of allergy to stainless ste el or polyolefin resin (12)Patients who are pregnant or may be pregnant (13)Patients who are or are scheduled to participat e in other clinical trials or interventional clinical studies (14)Other than the above, patients who are judged to be inappropriate for the purpose of this clinical tri al by the principal investigator or a sub-investigator due to medical conditions, etc. or safety reasons.