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The causative organism is not identified in some cases of infected aneurysms, a life-threatening condition. A 68-year-old man presented with chest/back pain and a 1-year history of intermittent fever and fatigue. Computed tomography revealed a thoracic aortic aneurysm. After several negative blood cultures, he was eventually diagnosed with an infected aneurysm caused by Helicobacter cinaedi via gene analysis of an aortic tissue specimen. As H. cinaedi is a low-virulence bacterium, infection with this pathogen should be suspected in cases of aortic aneurysms with unidentified causative organism and a long history of subjective symptoms. Detailed examinations, including polymerase chain reaction, should be conducted in such cases.

We report a case of active infective endocarditis in a young adult, affecting the anterior and posterior leaflets extensively. The patient underwent a mitral valve repair with extended sliding repair on the posterior leaflet and reconstruction using an autologous pericardial patch supported by an artificial chord on the anterior leaflet. Although we finally needed commissure closing for successful repair, we aggressively achieved a repair-oriented strategy using several techniques in a young patient who may have required mitral valve replacement.

症例は75歳，男性．左前下行枝慢性完全閉塞を伴う2枝病変に対して，平成20年2月12日心拍動下に左内胸動脈を左前下行枝へ，大伏在静脈を右冠動脈後下行枝に吻合した．3月6日に心タンポナーデによるショック状態となり，心嚢穿刺術にて回復した．3月29日に再び心タンポナーデによるショック状態となったため，心嚢穿刺術ののち右開胸にて心膜開窓術を施行した．その後4月16日にも心タンポナーデ再発をきたし，心嚢穿刺後に右開胸での心膜開窓術を再度行った．以後心嚢液の再貯留なく退院となったが，6月23日心タンポナーデ再発を来たし，7月2日胸腔-腹腔シャントシステム植え込みを行った．術後経過は良好で，2年経過した現在も心嚢液再発を認めていない．開心術後短期間に心タンポナーデを再発した稀な症例であり，胸腔-腹腔シャントシステムが有用であったので報告する．

症例は76歳,男性.平成17年5月21日左回旋枝の完全閉塞による急性心筋梗塞(後側壁)に対しシロリムス溶出性ステントを挿入された.残存する左前下行枝近位部の90%狭窄病変にに対し冠動脈バイパス術を施行することとなった.手術1週間前よりチクロピジン,手術2日前よりアスピリンを休薬し,ヘパリンを手術5日前より手術前まで静脈内持続投与し,6月9日に心拍動下に左内胸動脈を左前下行枝へ吻合した.手術当日夜よりヘパリン持続点滴を開始し,手術翌日よりアスピリンおよびチクロピジンを開始したが,術当日に急性心筋梗塞を発症した.緊急心臓カテーテル検査では,バイパスグラフトは良好に開存していたが左回旋枝に留置したステントの完全閉塞を認め,同閉塞に対しカテーテル治療を行い血流再開を得た.薬剤溶出性ステント挿入後はステント血栓症予防のために最低3ヵ月のチクロピジン投与および無期限のアスピリン投与が推奨されているが,出血性疾患の合併や外科手術のために抗血小板剤の休薬を要する状況も想定される.本報ではそのような患者における抗血小板療法,抗凝固療法につき検討した.

Though annuloplasty using a properly sized ring has been advocated in degenerative mitral regurgitation, restrictive annuloplasty using a down-sized ring is widely used in ischemic mitral regurgitation. We investigated the outcome of restrictive annuloplasty using a small (24- or 26-mm) ring in mitral regurgitation irrespective of the etiology.Nineteen patients underwent a restrictive annuloplasty using a 24-mm (n = 8) or 26-mm (n = 11) semi-rigid ring. The etiology included degenerative in 13 patients, ischemic in 3, endocarditis in 2, and congenital in 1. Body surface area of the patients implanted with the 24-mm ring was 1.40 ± 0.16 and 1.60 ± 0.18 m(2) for the 26-mm ring. Fifteen patients had 3+ or 4+ mitral regurgitation preoperatively.Two patients were converted to valve replacement for residual mitral regurgitation during the operation. One operative mortality associated with infection was observed. Echocardiogram at 29.4 ± 14.2 months postoperatively demonstrated mitral valve area of 2.0 ± 0.6 cm(2) for 24-mm ring and 2.2 ± 0.5 cm(2) for 26-mm ring with indexed mitral valve area of 1.4 ± 0.4 cm(2)/m(2) for both groups, and no mitral regurgitation more than 2+. Transmitral mean pressure gradient on rest was 4.7 ± 2.1 mmHg at last follow up. New York Heart Association class improved from 2.2 ± 0.7 to 1.2 ± 0.2 after the operation. No late death or reoperation was observed during the follow-up of 31.0 ± 15.0 months.Restrictive mitral annuloplasty using a small ring provided acceptable early and midterm results in patients with body surface area around 1.5 cm(2) without Barlow pathology. Restrictive annuloplasty may be another technical aspect to avoid valve replacement.

We herein report the case of 34-year-old woman with acute tricuspid valve infective endocarditis (IE) associated with a ruptured sinus of Valsalva and multiple septic pulmonary emboli. She had no history of medical problems, except for atopic dermatitis (AD). Blood cultures identified methicillin-sensitive Staphylococcus aureus. Despite the administration of two months of antibiotic therapy, the patient experienced recurrent pulmonary emboli and developed heart failure due to a left-to-right shunt, whereas the area of vegetation did not change in size. She subsequently underwent surgery for shunt closure and tricuspid valve replacement. The AD was thought to be the cause of the patient's bacteremia, which consequently resulted in aggressive right-sided IE.

We report an extended parasternal approach to aortic and tricuspid valves used in a 31-year-old man. The patient presented with a deformed sternum and severe adhesion between the sternum and right ventricular outflow tract, caused by postoperative mediastinitis, which lasted for 4 years after a radical operation for tetralogy of Fallot during his childhood. The extended parasternal approach provided a safe and excellent exposure of both aortic and tricuspid valves without postoperative chest wall instability.

心臓原発悪性リンパ腫は心臓または心外膜に限局する節外性悪性リンパ腫でありきわめて希な疾患である.今回,完全房室ブロックを初発症状とし,そののち上大静脈症候群を呈した心房中隔由来と思われる心臓原発悪性リンパ腫の1例を経験したので報告する.症例は65歳,女性.完全房室ブロックのため永久ペースメーカー植込み術を施行した.術前の心エコー検査では心臓内腫瘤は認めなかったが,その約6週間後に上大静脈症候群を発症した.心エコー検査では,心房中隔を中心とし右房内を占拠する巨大な腫瘤(径6×5cm)を認め,その一部が上大静脈-右房接合部に嵌頓していた.体外循環下に腫瘤を部分切除し上大静脈症候群を解除するとともに病理組織学的検査を行い悪性リンパ腫(diffuse large B-cell type)と診断した.術後諸検査により心臓以外のリンパ腫病変を認めなかったため,心臓原発悪性リンパ腫と診断し化学療法(T-COP療法)および自家末梢血幹細胞移植を行い完全寛解を得た.

左室心筋緻密化障害は,胎生期において左室心筋の緻密化の過程が障害されて起こる先天性心筋症の一つであり,心不全発症後の予後は不良である.本症は新生児・乳児期の重症心不全の原因として知られてきたが,最近成人期に発見される例が散見されるようになった.しかし,本疾患を合併した弁膜症患者に開心術を行った文献的報告はなされていない.今回われわれは,左室心筋緻密化障害を伴う重度の連合弁膜症症例に対し,二弁置換術を施行したので報告する.症例は62歳,男性.左室心筋緻密化障害およびIV度の大動脈弁・僧帽弁閉鎖不全症により心不全を発症し入院した.保存的治療により可及的に心不全をコントロールしたのち機械弁による大動脈弁・僧帽弁置換術を施行した.術後急性期の経過は良好で心機能の著明な改善を認め,術後34日目に退院した.今後は左室心筋緻密化障害による慢性期の心機能低下について慎重な経過観察が必要である.

The endoventricular circular patch plasty (Dor procedure) applies to patients with a left ventricular dysfunction due to an ischemic dilated ventricle. In the present study, we analyzed left ventricular energetics in patients who underwent the Dor procedure.We measured left ventricular contractility (end-systolic elastance; Ees), afterload (effective arterial elastance; Ea), and efficiency (ventriculoarterial coupling; Ea/Ees, and the ratio of stroke work and pressure-volume area; SW/PVA) based on the cardiac catheterization data before and after the Dor procedure in 8 patients with a postinfarction dyskinetic anterior left ventricular aneurysm. Concomitant procedures included coronary artery bypass grafting in all patients, mitral valve repair in one patient, and cryoablation in one patient. End-systolic elastance (Ees) and Ea were approximated as follows: Ees = mean arterial pressure/minimal left ventricular volume, and Ea = maximal left ventricular pressure/(maximal left ventricular volume-minimal left ventricular volume), and thereafter Ea/Ees and SW/PVA were calculated. The left ventricular volume was normalized with the body surface area.End-systolic elastance (Ees) increased after the Dor procedure (from 1.15 +/- 0.60 to 1.86 +/- 0.84 mm Hg x m2 x mL(-1), p0.01), thus resulting in an improvement in Ea/Ees and SW/PVA (from 2.94 +/- 1.11 to 1.64 +/- 0.49, p0.01, and from 0.426 +/- 0.110 to 0.559 +/- 0.082, p0.01, respectively), even though Ea did not substantially change (from 2.96 +/- 0.78 to 2.74 +/- 0.55 mm Hg x m2 x mL(-1), p = 0.4).Left ventricular contractility and efficiency improves after the Dor procedure in patients with a dyskinetic anterior left ventricular aneurysm. However, afterload does not change. The use of appropriate afterload-reducing therapy thus plays an especially important role in the management of patients who undergo the Dor procedure.

Background . The viability of cadaveric tracheal grafts undergoing cryopreservation is still unclear. We evaluated the limit of warm ischemia time before cryopreservation in rat tracheal isografts. Methods . Each isograft was harvested from donor rats 0 to 48 hours (0, 6, 12, 18, 24, and 48 hours) after circulatory arrest, immersed in the preservative solution, and stored in a deep freezer until reaching −80°C and then was kept in liquid nitrogen for 3 months. Heterotopic transplantation into the omentum was performed after the isografts were thawed. Graft morphology 3 months after transplantation was assessed. Results . The stepwise increase of warm ischemia time significantly reduced graft survival. A prolonged period of warm ischemia had a degenerative effect on both the epithelium and cartilage. The morphology of the epithelium and cartilage in isografts undergoing warm ischemia for less than 18 hours was better preserved, whereas it deteriorated in isografts undergoing warm ischemia for more than 24 hours. Conclusions . We thus conclude that the permissible period of warm ischemia before 3-month cryopreservation to maintain tracheal isograft viability is 18 hours in rats.

Background.Injection of allo-spleen cells (SC) followed by a single dose of cyclophosphamide (CP) can induce tolerance of tumor and/or skin allografts in mice. To minimize the damage caused by CP, fractionation of CP that can establish long-lasting skin graft survival, stable mixed chimerism, and in

A cyclophosphamide (CP)-induced tolerance system in mice that primarily consists of donor cell injection followed by CP-treatment was found useful for inducing a long-lasting allo- or xeno-tolerance to various solid organs. In the cells-followed-by-CP system, the sequential mechanisms of tolerance were clarified using the specific correlation between superantigens and certain T cell receptor (TCR) V beta segments. Those include the clonal destruction of antigen-stimulated mature T cells, the peripheral clonal deletion associated with peripheral chimerism, the intrathymic clonal deletion associated with intrathymic chimerism, and the clonal anergy. The generation of suppressor T cells was another important mechanism of tolerance in the late stage. Special care was taken to overcome the " hard" barriers of allo- or xeno-combinations by reducing the "split tolerance" produced through the clonal destruction mechanism. For this purpose, the tolerogen, antimitotic drugs, their doses, timing, route of administration, combined immunosuppressants, and supportive treatment were all crucial for successful induction of a long-lasting skin tolerance. This system may be applicable to human transplantation.

Because of the recent interest in human xenotransplantation, we investigated the possibility of inducing tolerance in a xenogeneic combination using cyclophosphamide (CP). Donor-specific prolongation of xenogeneic Fisher 344 (F344) rat skin graft survival for up to 60 days was induced in C57BL/6 (B6) mice by giving F344 bone marrow cells and spleen cells on day 0, CP on day 2, and monoclonal antibodies against murine TCR-alpha beta and NK1.1 on days--1 and 3. The inoculation of the xenogeneic cells brought accelerated repopulation of TCR-alpha beta+ T cells, even under the administration of anti-TCR-alpha beta mAb. The quick increase of the host TCR-alpha beta+ T cells caused by the xenogeneic cell injection was deeply suppressed by CP. Mixed lymphocyte reaction, CTL activity, and antibody production against donor F344 were profoundly suppressed for 50 days. Mixed xenogeneic chimerism was observed for 1 month after the inoculation of donor cells in the spleen and peripheral blood of the recipient B6 mice, but was never observed in the thymus. Moreover, when irradiated F344 cells were used in place of viable cells, chimerism was never detected and graft survival was only slightly prolonged. Clonal deletion of V beta 5- or V beta 11-bearing murine T cells was not observed on day 50 in the thymus or spleen of the recipient B6 mice. These results suggest that treatment with viable xenogeneic donor cells, CP, and mAbs against T and NK cells can induce a temporary peripheral mixed chimerism and donor-specific prolongation of xenogeneic skin graft survival. The destruction with CP of T and B cells that are xenoreactive and thus proliferating after antigen stimulation, followed by mechanism other than intrathymic clonal deletion, may be the mechanism of the hyporesponsiveness in the present system.

腹部大動脈瘤術後早期のMRSAグラフト感染に対して,閉鎖式カテーテル洗浄ドレナージが有効であった2例を経験した.症例1は,71歳男性で術後11日目から高熱を認め,グラフト周囲貯留液穿刺からMRSAを検出し,CTガイド下に6Frカテーテルを留置した.症例2は,77歳男性で術後2日目から高熱出現し,5日目から閉鎖式ドレーン抜去部から排膿ありMRSAを認め,右後腹膜経路でY-graft右脚部から洗浄用チューブを留置した.2例とも0.5%ポピドンヨード液と生理食塩水による閉鎖式間欠的洗浄およびバンコマイシンの局所注入を行った.抗生剤の全身投与を継続し,2例とも約4ヵ月後に治癒退院した.それぞれ退院後2年および1年3ヵ月を経過し再燃を認めていない.閉鎖式カテーテル洗浄ドレナージ法は,腹部大動脈瘤術後のグラフト感染に対し,有用な治療法であった.

Although a severely calcified ascending aorta is encountered infrequently, it presents formidable problems during cardiac surgery. We describe a case of severe aortic valve stenosis and coronary artery disease combined with a severely calcified ascending aorta. The patient was an 80-year-old man with a calcified ascending aorta. He successfully underwent an aortic valve replacement and a single coronary artery bypass graft (CABG) using a saphenous vein graft with the proximal end connected on a Dacron patch, which was used for aortoplasty of the calcified plate along the aortotomy. These procedures were performed under moderate hypothermia with aortic clamping. This patch aortoplasty can be a useful alternative in cases that require aortotomy and proximal anastomoses of a CABG on a calcified ascending aorta.

We report a successfully treated case of rapid progressive left ventricular (LV) thrombus with ischemic cardiomyopathy. Initially, the patient was scheduled to undergo only coronary artery bypass grafting. After two months, preoperative echocardiography revealed a previously undetected ball-like thrombus in the LV cavity. Surgical revascularization and thrombectomy were performed. No systemic embolism was associated with surgical manipulation during the perioperative period. Repeated preoperative evaluation for the presence of thrombus by transthoracic or transesophageal echocardiography is essential in cases of ischemic cardiomyopathy.

A 70-year-old female who had undergone pancreato-duodenectomy 1 month before, presented with back pain. Computed tomography (CT) revealed a saccular aneurysm in the distal aortic arch (40 mm in diameter) and she was referred to our department. Despite proper antibiotic treatment, CT revealed progressive enlargement of the aneurysm and operation was performed. The aneurysm was treated by debridement of the infected aortic tissue and in situ replacement with a rifampicin-soaked vascular prosthesis through L-incision approach. After surgery, antibiotics were administrated intravenously for 1 month, followed by oral antibiotics. The patient is doing well 1 year after the operation.

人工弁置換術後抗凝血薬療法中の20例に外科的処置を施行した. 10例に20回の抜歯を行ったが, ワーファリンは減量せず, 抜歯時のトロンボテスト (TT) は平均16%であった. 非開腹手術7例と開腹手術3例においてはワーファリンを減量してTT 40%前後で手術を施行した. 術中止血困難例はなく, 血栓性合併症も認めなかったが, 術後ヘパリン皮下注により活性凝固時間 (ACT) が200秒以上に延長した開腹手術の1例において開腹創からの出血を認めた. 人工弁置換術後の外科的処置に際しては, 血栓塞栓症や血栓弁を防止するためできるだけ抗凝血状態を維持することが望ましいが, 今回の検討から, 抜歯にはワーファリンの減量は不要であり, 開腹手術もTT 40%前後で十分可能であることが判明した. なお, ワーファリン減量中の補助療法としてヘパリンを使用する際は, ACTの過度の延長をきたさないように, 術前にその使用量を検討しておく必要がある.

A 26 day old neonate with Type B interrupted aortic arch, a ventricular septal defect and severe subaortic stenosis underwent a successful modified Van Praagh's operation, consisting of insertion of a graft between the main pulmonary artery and descending aorta, ligation of the patent ductus arteriosus and main pulmonary artery banding distal to the graft. This palliative procedure was effective and easily performed without the aid of cardiopulmonary bypass even in this severely ill neonate with such a complex defect.

We repaired a large defect in the posterior mitral leaflet after an extensive removal of infected tissue, using an extended leaflet sliding and annular downsizing with a small prosthetic ring in 2 patients with active endocarditis.

Cardiovascular syphilis, which used to be a well-recognized manifestation of tertiary syphilis, has become a rarity. In this report we describe a 47-year-old man presenting with an aneurysm of the distal arch and proximal descending aorta, a somewhat unusual presentation for a syphilitic aneurysm, and discuss the clinical features of cardiovascular syphilis.

Objective: We evaluated the feasibility of discordant xenotransplantation of the cryopreserved trachea with intermittent immunosuppression to help solve the shortage of donor tracheas. Methods: Two experiments were performed with heterotopic transplantation models in 14 guinea pigs and 85 rats. So that the minimal dose of FK506 for viable fresh xenografts could be determined, FK506 was given in escalating doses (0, 1.5, 2.5, and 3.5 mg/kg) for recipient animals after xenogeneic transplantation. With the goal of obtaining a long-term survival of the xenografts, the effect of cryopreservation on xenografts was assessed and thereafter different cycles of immunosuppression every third week were evaluated in fresh or cryopreserved xenografts in the second experiment. Results: An FK506 dosage of more than 2.5 mg/kg per day was much more effective than smaller dosages, as demonstrated by morphologic assessment. A higher dosage of FK506 potentially delayed the rejection of xenografts and can thus maintain tracheal xenograft viability for less than 4 weeks in rat recipients. In experiment 2, the cryopreserved xenografts showed less histologic viability than fresh xenografts but greater patency of the lumen. The patency of cryopreserved xenografts was favorably maintained for a longer period than that of fresh xenografts with either the same number or more cycles of immunosuppression. Conclusions: We conclude that the synergistic effect of cryopreservation and adequate intermittent immunosuppression may enable tracheal xenografts to remain viable over longer periods. (J Thorac Cardiovasc Surg 2001;121:241-8)

Murine T cell receptor (TCR) alpha beta intestinal intraepithelial lymphocytes (IEL), which express the CD8 molecule as a homodimer (CD8 alpha alpha), can be divided into two subsets: those which are CD4+ (CD4+CD8+alpha alpha) and those which are CD4- (CD4-CD8+alpha alpha). Here, we demonstrate that most TCR alpha beta CD4+CD8+alpha alpha IEL and TCR alpha beta CD4-CD8+alpha alpha IEL subsets appear to be of thymus origin, as neonatal thymectomy of BALB/c mice on Day 3 nearly eliminated both subsets. To further support this hypothesis, we demonstrate by grafting the thymus of CBF1 (BALB/c x C57BL/6) mice into nude mice that the thymus is capable of generating both TCR alpha beta CD4-CD8+alpha alpha IEL and TCR alpha beta CD4+CD8+alpha alpha IEL. However, which of the two TCR alpha beta IEL subsets is generated depends largely on the age of the thymus. The thymus from fetal up to 2 weeks of age generates predominantly TCR alpha beta CD4-CD8+alpha alpha IEL, but very scant amounts CD4+CD8+alpha alpha IEL. In contrast, the thymus after 2 weeks of age generates very little TCR alpha beta CD4-CD8+alpha alpha IEL, but generates an abundant amount of TCR alpha beta CD4+CD8+alpha alpha IEL. These results are consistent with the observation in euthymic mice that TCR alpha beta CD4-CD8+alpha alpha IEL precede the appearance of TCR alpha beta CD4+CD8+alpha alpha IEL by several weeks, thus further suggesting that the thymus is the major source of both TCR alpha beta IEL subsets.

Cyclophosphamide (CP)-induced tolerance which consists of a single i.p. injection of 200 mg/kg CP 2 days after priming with 1 × 10 8 donor spleen cells (SC), leads to long-lasting donor-specific skin allograft tolerance in H-2 compatible, multiminor antigen incompatible, murine strain combinations. In this system, the optimal dose of CP has been suggested to be 200 mg/kg, however, such a dose of CP causes strong myelosuppression. In the present study, we therefore attempted to reduce the dose of CP by administering anti-CD4 monoclonal antibody (mAb) before donor cell priming in this toleranceinducing system. When C3H/He (C3H; H-2 k , Mls-1 b ) mice were injected i.p. with 200 ltg anti-CD4 mAb on day -3, 1 × 10 8 AKR/J (AKR; H-2 k , Mls-1 a ) SC plus 3 × 10 7 bone marrow cells (BMC) i.v. on day -2 and then 100 mg/kg CP i.p. on day 0, a long-lasting donor-specific skin allograft tolerance was established; furthermore, the decreases in the number of leukocytes and the concentration of hemoglobin (Hb) in the peripheral blood were all less in the C3H mice treated with this new combined protocol than in the C3H mice injected with 200 mg/kg CP following the previous protocol. In the periphery of these tolerant mice, the number of donor-reactive Vβ6 + CD4 + T cells decreased and mixed chimerism was observed on both days 14 and 80. On the other hand, in the mice injected with AKR SC, BMC plus 100 mg/kg CP without anti-CD4 mAb, the number of Vβ6 + CD4 + T cells decreased on day 14, and then recovered by day 80 when the mixed chimerism disappeared. These results therefore suggest that the combined use of anti-CD4 . mAb with CP can reduce the dose of CP without affecting the efficiency of inducing donor-specific tolerance, probably due to the enhancement of the destruction effect of donor-reactive T cells by CP.

We investigated the role of natural killer (NK) cells in the development of autoantibody production in which (C57BL/6 x DBA/2) F1 (BDF1) hybrid mice were injected intravenously with spleen cells (SC) from parental DBA/2 mice (treated BDF1 mice). Treated BDF1 mice began to show an increase in serum anti-dsDNA antibody 2 weeks after injection, while the NK activity of their SC transiently increased initially in the first 1 to 2 weeks after injection, but subsequently decreased dramatically. Flow cytometric analysis suggested that this sequential change in NK activity correlated with the absolute number of host-derived NK1.1+ cells in SC from treated BDF1 mice. We demonstrated that the level of anti-dsDNA in serum is directly influenced by the level of NK activity in treated BDF1 mice. Depletion of NK cells by administration of anti-NK1.1 mAb accelerated the development of autoantibody production, whereas augmentation of NK activity by administration of poly-(I:C) inhibited the development of autoantibody production. This inhibitory effect of poly(I:C) was abolished by prior depletion of NK cells. Interestingly, suppression of autoantibody production was seen only when poly(I:C) was administrated within 1 week after injection of parental SC. Last, we demonstrate that adoptive transfer of interleukin-2 (IL-2)-activated NK cells had a protective effect against the development of autoantibody production. These findings imply that NK cells may have a protective role in lupus-like disease especially in its early stage. In addition, it opens up the possibility that adoptive immunotherapy with IL-2-activated NK cells can delay or even prevent the development of autoimmune disease.

Objective: The maximal period of cryopreservation for the trachea is still unsolved. We assessed the maximal period of cryopreservation using the Bicell biofreezing vessel as an easy and cheap slow-freezing instrument for viable tracheal grafts in 95 rats. Methods: Each isograft was harvested from 17 donor rats, immersed in the preservative solution, and stored in a Bicell device in a deep freezer at –80°C. The tracheal isografts were then randomly assigned to 9 groups according to cryopreservation periods ranging from 0 to 12 months. Included in the 9 groups were 2 subgroups (n = 6 per subgroup) that were observed immediately after being thawed and 1 month after heterotopic transplantation into the omentum after being thawed. Four subgroups (n = 6 per subgroup) were added according to the cryopreservation period for 1, 3, 6, and 12 months to evaluate the graft morphology 3 months after being thawed and transplanted heterotopically. Results: A prolonged period of cryopreservation had a degenerative effect on both the epithelium and cartilage. One month after transplantation, degeneration was more pronounced in the cartilage than in the epithelium, as characterized by the viable chondrocyte ratio and the epithelial score of isografts undergoing cryopreservation for more than 9 months. Three months after transplantation, the morphology of the epithelium and cartilage in isografts undergoing cryopreservation for less than 3 months was better preserved, whereas the morphology of both deteriorated in isografts undergoing cryopreservation for more than 6 months. Conclusions: We conclude that the permissible period of cryopreservation to maintain tracheal isograft viability in this simple system using a Bicell biofreezing vessel is 3 months. (J Thorac Cardiovasc Surg 1999;117:1070-6)