Coronary fistulae are occasionally detected using echocardiography or coronary angiography. We report a patient with cardiac tamponade because of a ruptured aneurysm of a coronary artery fistula. A 60-year-old man was referred to our hospital with sudden onset of chest pain and unconsciousness. He was initially diagnosed with cardiac tamponade for type A acute aortic dissection, and an emergency operation was performed. A large amount of bleeding was seen in the pericardium, but aortic dissection around the arch was not observed. Instead, a ruptured aneurysm of a coronary-pulmonary fistula was identified on the pulmonary artery root. The aneurysm was resected, and the fistula was closed by ligation. The patient’s postoperative progress was good, and he was discharged on postoperative day 12 without any abnormalities on the coronary arteriogram. Preoperative diagnosis of the rupture of the small coronary artery aneurysm is difficult in such an emergency case, and this possibility should be considered in differential diagnosis when the CT image does not show typical aortic dissection.

Blood access is a lifeline for dialysis patients. However, serious problems such as stenosis or obstruction of access blood vessels, which are life-threatening conditions in daily clinical practice, still remain. One of the most promising candidates for solving these problems may be Biotube blood vessels. More than 20 years have passed since the development of in-body tissue architecture (iBTA), a technology for preparing tissues for autologous implantation in patients. The tissues obtained by iBTA do not elicit immunological rejection, which is one of the ultimate goals of regenerative medical engineering; however, their practical applications were quite challenging. The seemingly unorthodox iBTA concepts that do not follow the current pre-established medical system may not be readily accepted in general medicine. In contrast, there are many diseases that cannot be adequately addressed even with the latest and most advanced medical technology. However, iBTA may be able to save patients with serious diseases. It is natural that the development of high-risk medical devices that do not fit the corporate logic would be avoided. In order to actively treat such largely unattached diseases, we started Biotube Co., Ltd. with an aim to contribute to society. Biotubes induced by iBTA are collagenous tubular tissues prepared in the patient’s body for autologous implantation. The application of Biotubes as tissues for vascular implantation has been studied for many years. Biotubes may have excellent potential as small-diameter artificial blood vessels, one of the most difficult to clinically achieve. Their possibility is currently being confirmed in preclinical tests. Biotubes may save hundreds of thousands of patients worldwide annually from amputation. In addition, we aim to eliminate the recuring access vascular problems in millions of dialysis patients. This study provides an update on the current development status and future possibilities of Biotubes and their preparation molds, Biotube Makers.

There is a need for small diameter vascular substitutes in the absence of available autologous material. A small diameter, long tissue engineered vascular graft was developed using a completely autologous approach called “in body tissue architecture technology (iBTA)”. The aim of this pilot study was to evaluate “Biotubes”, iBTA induced autologous collagenous tubes, for their potential use as small diameter vascular bypass conduits. Biotubes (internal diameter 4 mm, length 50 cm, wall thickness 0.85 mm) were prepared by subcutaneous embedding of plastic moulds (Biotube Maker) in three goats for approximately two months. Allogenic Biotubes (length 10 cm [n = 2], 15 cm [n = 2], 22 cm [n = 2]) were bypassed to both carotid arteries by end to side anastomosis with their ligation between the anastomoses in another three goats. Residual Biotubes were examined for their mechanical properties. After four weeks, the harvested Biotubes were evaluated histologically. All Biotubes had sufficient pressure resistance, approximately 3000 mmHg. Although wall thickening occurred at two proximal anastomosis sites, all six grafts were patent without luminal thrombus formation, stenosis, or aneurysm deformation throughout the implantation period. Endothelial cells covered both anastomosis sites almost completely, with partial covering in the central portion of the grafts. Furthermore, α smooth muscle actin positive cells infiltrated the middle layer along almost the entire graft length. This preliminary study showed that small diameter, long, tissue engineered Biotubes could function properly as arterial bypass conduits in a large animal for one month without any abnormal change in vascular shape. Thus, small diameter, long Biotubes are potentially viable conduits, which are biocompatible and labour non-intensive, and therefore, suitable for clinical practice. Additionally, Biotubes can start the regeneration process in a short period of time.