Publications by authors named "Yuzuru Sakakibara"

77 Publications

Effect of Initial Graft Tension During Anterior Talofibular Ligament Reconstruction on Ankle Kinematics, Laxity, and In Situ Forces of the Reconstructed Graft.

Am J Sports Med 2020 03 13;48(4):916-922. Epub 2020 Feb 13.

Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan.

Background: Although a variety of surgical procedures for anterior talofibular ligament (ATFL) reconstruction have been reported, the effect of initial graft tension during ATFL reconstruction remains unclear.

Purpose/hypothesis: This study investigated the effects of initial graft tension on ATFL reconstruction. We hypothesized that a high degree of initial graft tension would cause abnormal kinematics and laxity.

Study Design: Controlled laboratory study.

Methods: Twelve cadaveric ankles were tested with a robotic system with 6 degrees of freedom to apply passive plantarflexion and dorsiflexion motions and a multidirectional load. A repeated measures experiment was designed with the intact ATFL, transected ATFL, and reconstructed ATFL at initial tension conditions of 10, 30, 50, and 70 N. The 3-dimensional path and reconstructed graft tension were simultaneously recorded, and the in situ forces of the ATFL and reconstructed graft were calculated with the principle of superposition.

Results: Initial tension of 10 N was sufficient to imitate normal ankle kinematics and laxity, which were not significantly different when compared with those of the intact ankles. The in situ force on the reconstructed graft tended to increase as the initial tension increased. In situ force on the reconstructed graft >30 N was significantly greater than that of intact ankles. The in situ force on the ATFL was 19 N at 30° of plantarflexion. In situ forces of 21.9, 30.4, 38.2, and 46.8 N were observed at initial tensions of 10, 30, 50, and 70 N, respectively, at 30° of plantarflexion.

Conclusion: Approximate ankle kinematic patterns and sufficient laxity, even with an initial tension of 10 N, could be obtained immediately after ATFL reconstruction. Moreover, excessive initial graft tension during ATFL reconstruction caused excessive in situ force on the reconstructed graft.

Clinical Relevance: This study revealed the effects of initial graft tension during ATFL reconstruction. These data suggest that excessive tension during ATFL reconstruction should be avoided to ensure restoration of normal ankle motion.
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http://dx.doi.org/10.1177/0363546520902725DOI Listing
March 2020

3D MRI evaluation of morphological characteristics of lateral ankle ligaments in injured patients and uninjured controls.

J Orthop Sci 2020 Jan 16;25(1):183-187. Epub 2019 Mar 16.

Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan.

Background: With ultrasonography or 2D magnetic resonance imaging (MRI) of the lateral ankle ligament, it is particularly difficult to show the entire calcaneofibular ligament (CFL). The purpose of this study was to evaluate the morphological characteristics of the lateral ankle ligaments in injured patients and uninjured controls using 3D MRI.

Methods: A total of 64 ankles of 59 healthy volunteers and lateral ligament injury patients (mean age of 32.4 years) were examined. The 64 ankles included a healthy group of 11 ankles, an acute injury group of 12 ankles that underwent MRI a month after injury, and a chronic injury group of 41 ankles that underwent MRI more than 3 months after injury. Using a 3.0-T MRI system, imaging was done with fast imaging employing steady-state acquisition cycled phases. Oblique sagittal images that most clearly depicted the entire anterior talofibular ligament (ATFL) and CFL were prepared manually and evaluated using a workstation.

Results: In the healthy group, both the ATFL and CFL were clearly and entirely visualized. The mean width in the central portion was 4.0 ± 1.0 mm in the ATFL and 4.8 ± 0.6 mm in the CFL. 3D MRI in the acute injury group showed findings of diffuse swelling with hyperintensity in the ATFL of all patients. The CFL in 7 of 12 ankles showed findings of diffuse swelling with hyperintensity. In the chronic injury group, morphological abnormalities of the ATFL were seen in 19 of 41 ankles. The ligament signal disappeared in 2 ankles, thinned in 4 ankles, and showed swelling in 13 ankles. Morphological abnormalities of the CFL were seen in 17 of 41 ankles. The ligament signal disappeared in 1 ankle, thinned in 2 ankles, and showed swelling in 14 ankles.

Conclusion: 3D MRI may be a useful modality to visualize both the ATFL and the CFL.
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http://dx.doi.org/10.1016/j.jos.2019.02.018DOI Listing
January 2020

Kinematics and Laxity of the Ankle Joint in Anatomic and Nonanatomic Anterior Talofibular Ligament Repair: A Biomechanical Cadaveric Study.

Am J Sports Med 2019 03 25;47(3):667-673. Epub 2019 Jan 25.

Department of Orthopaedic Surgery, School of Medicine, Sapporo Medical University, Sapporo, Japan.

Background: Although it is crucial to accurately identify the anterior talofibular ligament (ATFL) attachment site, it may not be feasible to fully observe the ATFL attachment site during arthroscopic surgery. As a result, the repair position might often be an unintentionally nonanatomic ATFL attachment site.

Hypothesis: Anatomic ATFL repair restores kinematics and laxity to the ankle joint, while nonanatomic ATFL repair does not.

Study Design: Controlled laboratory study.

Methods: Seven normal fresh-frozen human cadaveric ankles were used. The ankles were tested with a 6 degrees of freedom robotic system. The following ankle states were evaluated: intact, ATFL injured, ATFL anatomic repair, and ATFL nonanatomic repair. The ATFL nonanatomic repair position was set 8 mm proximal from the center of the ATFL attachment site of the fibula. For each state, a passive plantarflexion (PF)-dorsiflexion (DF) kinematics test and a multidirectional loading test (anterior forces, inversion moment, and internal rotation moment) were performed.

Results: The kinematics and laxity of the anatomic repair were not significantly different from those of the intact state. In nonanatomic repair, the inversion-eversion angle showed significant inversion (3.0°-3.4°) from 5° to 15° of DF, and the internal rotation-external rotation angle showed significant internal rotation (2.0°) at neutral PF-DF versus the intact state. In addition, internal rotation laxity was significantly increased (5.5°-5.8°) relative to the intact state in the nonanatomic repair at 30° and 15° of PF. There were no significant differences in anterior-posterior translation between the repairs.

Conclusion: Although the anatomic ATFL repair state did not show significant differences in kinematics and laxity relative to the intact state, the nonanatomic ATFL repair state demonstrated significant inversion and internal rotation kinematics and internal rotation laxity when compared with the intact state.

Clinical Relevance: Nonanatomic repair alters kinematics and laxity from the intact condition.
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http://dx.doi.org/10.1177/0363546518820527DOI Listing
March 2019

Early surgical management of traumatic dislocation of the tibialis posterior tendon: a case report and review of the literature.

J Med Case Rep 2018 Nov 23;12(1):348. Epub 2018 Nov 23.

Department of Orthopaedic Surgery, Sapporo Medical University, Sapporo, Japan.

Background: Traumatic dislocation of the tibialis posterior tendon at the ankle is a rare injury. Some of these cases are misdiagnosed as ankle sprains and are not treated properly. In addition, because the conservative treatment is not as effective as the surgical treatment, it is essential that patients be diagnosed early so that proper surgical treatment can be performed. We report the early surgical management of traumatic dislocation of the tibialis posterior tendon.

Case Presentation: A 44-year-old Japanese man, who was a karate coach, was injured while acting as an umpire in a karate competition. On the same day of his injury, he came to our hospital. He complained of swelling and pain in the medial malleolus. Anterior dislocation of the tibialis posterior tendon was detected upon palpation. Magnetic resonance imaging showed the presence of anterior dislocation of the tibialis posterior tendon with retinaculum injury. Four days after the injury, we performed the Das De procedure as the surgical treatment. Three months after the surgery, the patient was able to participate in karate again.

Conclusions: Dislocation of the tibialis posterior tendon is likely to be misdiagnosed, thus delaying the start of proper treatment. It is essential to diagnose the patient accurately by carefully assessing the physical symptoms manifested. Moreover, magnetic resonance imaging can also be used for better diagnosis, thereby leading to an early and proper surgical treatment.
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http://dx.doi.org/10.1186/s13256-018-1872-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6251192PMC
November 2018

Suture-button fixation and anterior inferior tibiofibular ligament augmentation with suture-tape for syndesmosis injury: A biomechanical cadaveric study.

Clin Biomech (Bristol, Avon) 2018 12 12;60:121-126. Epub 2018 Oct 12.

Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, South 1 West 16, Chuo-ku, Sapporo, Hokkaido 060-8543, Japan.

Background: Suture-button (SB) fixation has been widely performed for syndesmosis injuries, but it has been reported unstable in some biomechanical studies. The purpose of this study was to evaluate the stability of the syndesmosis using SB fixation with anterior inferior tibiofibular ligament augmentation using suture-tape (ST).

Methods: Eight normal fresh-frozen cadaveric legs were used. After initial tests of intact and injured models, SB fixation, SB fixation with ST augmentation, ST augmentation alone, and screw fixation were performed sequentially for each specimen. Loading tests stimulating dorsiflexion, inversion, and external rotation of the ankle joint were performed for each model. The tibiofibular diastasis (TFD) and the fibular rotational angle related to the tibia (FRA) were measured using a magnetic tracking system.

Findings: In the injured model, both TFD and FRA increased significantly compared with the intact model in all directions (P < .05). In the SB fixation model, TFD and FRA generally showed significant increases (P < .05, except for TFD in external rotation). In the SB fixation with ST augmentation model and ST augmentation alone, TFD and FRA were not significantly different compared with the intact model (P > .05). In the screw fixation model, FRA with inversion force at the ankle was significantly decreased compared with the intact model (P = .027).

Interpretation: SB fixation alone did not provide stability of the syndesmosis, and screw fixation became too rigid compared with the intact model. Using ST augmentation achieved dynamic stability similar to the intact model for syndesmotic injuries.
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http://dx.doi.org/10.1016/j.clinbiomech.2018.10.014DOI Listing
December 2018

Modified distal tibial oblique osteotomy for osteoarthritis of the ankle: Operative procedure and preliminary results.

J Orthop Sci 2019 Mar 21;24(2):306-311. Epub 2018 Sep 21.

Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, South-1, West-16, Chuoku, Sapporo, Hokkaido, 060-8543, Japan.

Background: Low tibial osteotomy is an effective joint-preserving surgery for ankle arthritis. However, poor postoperative wound healing, infection, and delayed or non-union of bones remain significant concerns. We describe a modified distal tibial oblique osteotomy procedure and report preliminary results for varus ankle arthritis.

Methods: The osteotomy path consisted of an oblique doglegged line from the lateral end of the distal tibia to a proximal point about one-third from the lateral edge and continuing along an arc defined by virtual coronal-plane rotation of the doglegged line to the medial edge. After osteotomy, the distal tibial fragment was rotated distally in the coronal plane for realignment while maintaining contact with the proximal tibia and the distal tibial fragment. The resulting wedge-shaped gap was filled with artificial bone blocks and tibial bone projecting medially from rotation. A locking plate was then applied for stabilization. We evaluated 7 ankles from 6 osteoarthritis patients both clinically and radiographically following this procedure.

Results: Bone union was achieved within 3 months for all patients. The Japanese Society for Surgery of the Foot ankle-hindfoot scale improved from a mean of 38.4 points preoperatively to 85.7 points at the latest follow-up. No wound healing problems, infections, or nerve disturbances were observed. Multiple radiographic parameters were also improved following the operation.

Conclusions: This procedure maintains close bone contact for better postoperative union, obviates the need for iliac bone harvesting, and reduces tension on medial soft tissue. We believe these modifications are potential advantages for achieving stable results in patients with ankle osteoarthritis.
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http://dx.doi.org/10.1016/j.jos.2018.08.020DOI Listing
March 2019

ACL Function in Bicruciate-Retaining Total Knee Arthroplasty.

J Bone Joint Surg Am 2018 Sep;100(17):e114

Department of Orthopedic Surgery (Y.O., A.T., Y.S., H.S., and T.Y.) and Second Department of Anatomy (M.F.), Sapporo Medical University School of Medicine, Sapporo, Japan.

Background: Bicruciate-retaining total knee arthroplasty (BCR-TKA) is attracting attention because of the functional and satisfaction outcomes associated with keeping the anterior cruciate ligament (ACL) intact. However, knowledge of the functional importance of the ACL after BCR-TKA is limited. We performed a biomechanical investigation of ACL function following BCR-TKA compared with that in the intact knee.

Methods: We investigated 8 fresh-frozen human cadaveric knees using a 6-degrees-of-freedom robotic system that allowed natural joint motion. Three knee states-intact knee, BCR-TKA, and BCR-TKA with ACL transection (BCR-TKA + ACLT)-were evaluated. For each knee state, the kinematics during passive flexion-extension motion (from 0° to 120°) and anteroposterior laxity at 0°, 15°, 30°, 60°, and 90° of flexion in response to a 100-N load were investigated. The recorded knee motions of the intact and BCR-TKA knees during each test were repeated after ACLT to calculate the ACL in situ force.

Results: The femur in the BCR-TKA group translated posteriorly and rotated externally during passive knee flexion and was in an anterior position compared with the femur in the intact-knee state. After ACLT, the femur translated posteriorly, compared with the BCR-TKA group, at 0° and 10° (p < 0.05). The anteroposterior laxities of the BCR-TKA and intact knees were comparable at all flexion angles and increased 2-fold or more after ACLT (p < 0.01). The ACL in situ force in the BCR-TKA knees was 2-fold to 6-fold higher than that in the intact knees at 0°, 15°, 90°, and 120° during a passive path (p < 0.05) and equivalent to that in the intact knees under anterior loading.

Conclusions: The preserved ACL in the BCR-TKA knees was functional, like the ACL in the intact knees, under anterior tibial loading and contributed to good anteroposterior stability. However, the kinematics and ACL in situ force differed between the intact and BCR-TKA knees during passive flexion-extension movements.

Clinical Relevance: Surgeons may not be able to prevent overtensioning of the ACL during a standardized BCR-TKA procedure, which could potentially limit range of motion.
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http://dx.doi.org/10.2106/JBJS.18.00099DOI Listing
September 2018

Effect of Initial Graft Tension During Calcaneofibular Ligament Reconstruction on Ankle Kinematics and Laxity.

Am J Sports Med 2018 10 20;46(12):2935-2941. Epub 2018 Aug 20.

Department of Orthopaedic Surgery, School of Medicine, Sapporo Medical University, Sapporo, Hokkaido, Japan.

Background: Although a variety of surgical procedures for lateral ankle ligament reconstruction have frequently been reported, little is known about the effects of initial graft tension. Purpose/Hypothesis: The purpose was to investigate the effects of initial graft tension in calcaneofibular ligament (CFL) reconstruction. It was hypothesized that a high degree of initial graft tension would cause abnormal kinematics, laxity, and excessive graft tension.

Study Design: Controlled laboratory study.

Methods: Twelve cadaveric ankles were tested with a 6 degrees of freedom robotic system to apply passive plantarflexion-dorsiflexion motion and multidirectional loads. A repeated-measures experiment was designed with the CFL intact, CFL transected, and CFL reconstructed with 4 initial tension conditions (10, 30, 50, and 70 N). The 3-dimensional path and reconstructed graft tension were simultaneously recorded.

Results: The calcaneus in CFL reconstruction with an initial tension of 70 N had the most eversion relative to the intact condition (mean eversion translations of 1.2, 3.0, 5.0, and 6.2 mm were observed at initial tensions of 10, 30, 50, and 70 N, respectively). The calcaneus also moved more posteriorly with external rotation as the initial tension increased. The reconstructed graft tension tended to increase as the initial tension increased.

Conclusion: Ankle kinematic patterns and laxity after CFL reconstruction tended to become more abnormal as the initial graft tension increased at the time of surgery. Moreover, excessive initial graft tension caused excessive tension on the reconstructed graft.

Clinical Relevance: This study indicated the importance of initial graft tension during CFL reconstruction. Overtensioning during CFL reconstruction should be avoided to imitate a normal ankle.
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http://dx.doi.org/10.1177/0363546518790254DOI Listing
October 2018

The distal margin of the lateral malleolus visible under ankle arthroscopy (articular tip) from the anteromedial portal, is separate from the ATFL attachment site of the fibula: A cadaver study.

J Orthop Sci 2018 May 1;23(3):565-569. Epub 2018 Feb 1.

Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan.

Purpose: The purpose of this study was to evaluate the relationship between the lateral malleolus view under ankle arthroscopy and the anterior talofibular ligament (ATFL) attachment site.

Methods: Seven normal ankles from Thiel-embalmed cadavers were investigated. Ankle arthroscopy was performed using a 2.7 mm-diameter, 30-degree, oblique-viewing endoscope. An antero-medial portal (AM), a medial midline portal (MML), and an antero-central portal (AC) were created in order, and the ankle arthroscope was inserted. The lateral malleolus was visualized as distally as possible, and the site that appeared to be the distal margin was marked with a 1.5 mm-diameter K-wire. Visualization with arthroscopy was carried out from all portals to mark the distal margin, and the ankle was subsequently exposed to directly measure the distance from the center of the ATFL attachment site at the fibula to each marking.

Results: The distances from the ATFL attachment site to the markings made under arthroscopy from the AM, MML, and AC portals were 10.4 ± 2.6 mm, 7.4 ± 1.9 mm, and 7.3 ± 1.9 mm, respectively. Compared to markings made from the MML or AC portal, the marking made from the AM portal was significantly further away from the ATFL attachment site.

Conclusions: A typical ankle arthroscopy portal may not allow complete visualization of the tip of the lateral malleolus, indicating that it may not be feasible to thoroughly observe the ATFL attachment site. It is necessary to perform arthroscopic surgeries with the understanding that the distal margin of the lateral malleolus that appears under ankle arthroscopy is 7-10 mm proximal to the ATFL attachment site.
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http://dx.doi.org/10.1016/j.jos.2018.01.002DOI Listing
May 2018

Suture-Button Fixation and Mini-Open Anterior Inferior Tibiofibular Ligament Augmentation Using Suture Tape for Tibiofibular Syndesmosis Injuries.

J Foot Ankle Surg 2018 Jan - Feb;57(1):159-161

Professor, Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Hokkaido, Japan.

Tibiofibular fixation using suture-button implants is an optional method for the surgical treatment of syndesmosis injuries. Although good clinical outcomes have been reported, inadequate stability between the tibia and fibula has also been documented. Thus, suture-button fixation is not considered the reference standard. For surgical treatment of lateral ligament injuries of the ankle, good treatment outcomes have also been reported with ligament augmentation using nonabsorbable suture tape. Ligament augmentation tape with suture-button fixation could also be promising for improved treatment outcomes in syndesmosis injuries. We describe suture-button fixation together with mini-open anterior inferior tibiofibular ligament augmentation using suture tape for treatment of syndesmosis injuries.
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http://dx.doi.org/10.1053/j.jfas.2017.07.007DOI Listing
August 2018

Tibiotalocalcaneal Arthrodesis Using a Soft Tissue-Preserved Fibular Graft for Treatment of Large Bone Defects in the Ankle.

Foot Ankle Int 2017 Jun 8;38(6):671-676. Epub 2017 Mar 8.

2 Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Hokkaido, Japan.

Background: Pathogenesis of ankle disorders with a large bone defect is varied and treatment for those problems is challenging for orthopaedic surgeons. The aims of this study were to present an operative technique of arthrodesis for the reconstruction of the ankle and hindfoot with a large bone defect using a soft tissue-preserved fibular strut graft and to report outcomes of consecutively treated patients.

Methods: Twelve feet from 11 patients, including feet with aseptic necrosis of the talus and total ankle implant loosening, were treated. Bone defects were filled using iliac bone and/or resected fibula and tibiotalocalcaneal arthrodesis was performed using a retrograde intramedullary nail. A modified transfibular approach was used to expose the affected joint while preserving the lateral to posterior skin and soft tissues on the fibula. The periods of bony fusion and outcomes were radiographically and clinically evaluated. The mean follow-up period was 33.4 months.

Results: Bony fusion was achieved within 3 months in all cases. Coronal and sagittal alignments were acceptable, and the mean American Orthopaedic Foot & Ankle Score improved from 53.8 to 75.5 at the final follow-up. All patients graded their results of treatment as "satisfied."

Conclusion: This procedure did not require special techniques and it should be applicable to complicated cases with large bone defects. High fusion rates that we believe are due to preserving blood supply to the fibular graft can be expected with preservation of the hindfoot height.

Level Of Evidence: Level IV, case series.
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http://dx.doi.org/10.1177/1071100717696252DOI Listing
June 2017

Life-threatening acute heart failure due to primary cardiac undifferentiated pleomorphic sarcoma.

Intern Med 2014 15;53(16):1775-7. Epub 2014 Aug 15.

Department of Cardiology, Ibaraki Prefectural Central Hospital, Japan.

A 41-year-old man was admitted with acute heart failure and shock status. An echocardiogram showed a mobile tumor obstructing blood flow through the mitral valve with a stalk on the posterior left atrium (LA) wall. Emergent open-heart surgery was performed to resect the tumor (77×36×30 mm). Histological examination confirmed that it was an undifferentiated pleomorphic sarcoma. Unfortunately, positron emission tomography performed five months after surgery demonstrated a local recurrence around the right pulmonary vein and LA. We performed proton beam radiotherapy to treat the local recurrence, and it was effective. The patient has survived more than one year since the first life-threatening heart failure episode.
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http://dx.doi.org/10.2169/internalmedicine.53.2124DOI Listing
June 2015

Focusing on delayed clearance for identifying small-sized metastatic lung tumors using synchrotron radiation angiography with a highly sensitive receiver.

Gen Thorac Cardiovasc Surg 2014 Sep 11;62(9):553-9. Epub 2014 Jun 11.

Department of Thoracic and Cardiovascular Surgery, Graduate School of Comprehensive Human Science, University of Tsukuba, Tsukuba, 305-8575, Japan,

Objectives: To detect metastatic lung tumors of less than 1 mm in size by focusing on the clearance of contrast material using synchrotron radiation (SR) angiography characterized by high spatial resolution and high-sensitivity receiver.

Methods: C6 cells, derived from rat glioma cells, were injected to the rat tail vein. Two weeks after injection, the rats underwent SR angiography using a high-gain avalanche rushing amorphous photoconductor (HARP) receiver of extra-high sensitivity with high contrast resolution. The 256-grayscale value was employed in the analysis of images.

Results: 19 nodules were identified in images. The tumors were confirmed histopathologically. The average tumor size was 621±193 µm. The clearance curve of the densities was expressed as a logarithm function. Tumors showed delayed clearance of contrast material, taking up to 28 s, compared with arteries, which cleared rapidly at 8 s. In 256 grayscale, the distance was 50. This gap in density clearance made it possible to identify tumors.

Conclusions: SR angiography with a HARP receiver provides high sensitivity and spatial resolution and makes it possible to diagnose metastatic lung tumors of less than 1 mm in size by focusing on differences in the clearance times of contrast material.
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http://dx.doi.org/10.1007/s11748-014-0430-xDOI Listing
September 2014

Shrinkage temperature and anti-calcification property of triglycidylamine-crosslinked autologous tissue.

J Artif Organs 2014 Sep 4;17(3):265-71. Epub 2014 May 4.

Department of Cardiovascular Surgery, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8575, Japan.

Since bioprosthetic valve dysfunction may arise due to histological calcification in the crosslinking process by glutaraldehyde (GA), non-GA crosslinking reagents have been investigated. We compared the efficacy of triglycidylamine (TGA), a newly synthesized epoxy compound, and GA as crosslinking reagents for the treatment of autologous tissues. We assessed the strength of crosslinked tissues using shrinkage temperature (Ts) measured by differential scanning calorimetry. We also conducted subdermal allografting of the crosslinked pericardium and thoracic aorta in rats, and verified the anti-calcification efficacy of TGA by histological evaluations with von Kossa stain, and immunological evaluations using tenascin-C (TN-C) or matrix metalloproteinase-9 (MMP-9). TGA treatment resulted in slower increases in Ts of the pericardium, and it required 9-12 h to reach Ts achieved by GA. In subdermal implantation of rat tissues, calcium content was lower in the TGA group than in the GA groups (p < 0.005). The expression site of TN-C and MMP-9 differed from the primary location of calcium deposition in the thoracic aorta treated with TGA suggesting a different underlying mechanism in calcification between GA and TGA crosslinking. In conclusion, TGA crosslinking in the allograft showed superior anti-calcification effect as compared to brief treatment by GA, although TGA crosslinking process was slow.
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http://dx.doi.org/10.1007/s10047-014-0768-yDOI Listing
September 2014

Memorial address for Motokazu Hori (1929-2013).

Gen Thorac Cardiovasc Surg 2014 May;62(5):269-70

, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan,

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http://dx.doi.org/10.1007/s11748-014-0384-zDOI Listing
May 2014

Cardiopulmonary bypass induces recruitment of bone marrow-derived leukocytes to the lungs in monkeys.

Ann Thorac Surg 2014 Feb 25;97(2):617-22. Epub 2013 Dec 25.

Department of Cardiovascular Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.

Background: A bone marrow (BM) response induced by cardiopulmonary bypass (CPB) as a systemic inflammatory reaction has previously been postulated but not clarified. Newly released polymorphonuclear leukocytes (PMNs) and monocytes from the BM are known to be immature, indicating their greater potential to damage tissue. The present study aimed to examine the kinetics of BM-derived leukocytes associated with CPB in a nonhuman primate model.

Methods: Normothermic CPB was performed in cynomolgus monkeys for 2 hours through a median sternotomy. Leukocyte precursors were labeled in the BM of the monkeys in vivo by an intravenous injection of 5-bromo-2'-deoxyuridine (BrdU), and their release into the circulation and recruitment to the lungs after operation with or without CPB (control group) were monitored over time by flow cytometry.

Results: In normal-state monkeys, the calculated transit time of BrdU-labeled PMNs (PMNBrdU) through the BM was 143.6±4.5 hours and that of monocytes was 100.9±7.6 hours. CPB caused a rapid release of PMNs and monocytes from the BM, shortened their transit through the BM to 92.0±4.1 and 60.3±2.9 hours, respectively, and further induced their increased appearance in the alveolar spaces, with a significant increase in both interleukin (IL)-6 and IL-8 levels in the bronchoalveolar lavage fluid (BALF) 24 hours after CPB.

Conclusions: CPB accelerated the release of PMNs and monocytes from the BM and their recruitment to the lungs in our monkey model, indicating that this model is relevant for monitoring the kinetics of BM-derived leukocytes in humans.
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http://dx.doi.org/10.1016/j.athoracsur.2013.10.072DOI Listing
February 2014

Early heparin administration attenuates tissue factor-mediated thrombin generation during simulated cardiopulmonary bypass.

J Card Surg 2014 Jan 25;29(1):35-40. Epub 2013 Nov 25.

Department of Cardiovascular Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.

Background: We tested the hypothesis that heparin administration prior to the emergence of tissue factor (TF) would increase plasma TF pathway inhibitor (TFPI) and attenuate TF-mediated thrombin generation during simulated cardiopulmonary bypass (CPB).

Methods: Human blood was recirculated for 120 minutes using an oxygenator and roller pump. Four groups were examined: control group (heparin 3.75 U/mL, in donor blood, n = 7), rTF group (heparin + recombinant TF 1000 pg/mL, in donor blood, n = 7), TFPI boost group (heparin, in preheparinized donor blood, n = 8), and rTF + TFPI boost group (heparin + rTF, in preheparinized blood, n = 7). In the two TFPI boost groups, 50 U/kg of heparin was given to the donors intravenously five minutes before donation to boost plasma TFPI levels. Total plasma TFPI, thrombin-antithrombin complex, and prothrombin fragment F1+2 levels were measured before and during CPB.

Results: Preheparinization increased total plasma TFPI levels by a factor of 8.0. Administration of rTF significantly enhanced the generation of F1+2 (p = 0.0002). The heparin-induced TFPI elevation reduced both thrombin-antithrombin complex and F1+2 to control levels in rTF + TFPI boost group (p = 0.0158 for thrombin-antithrombin complex, p < 0.0001 for F1+2 ). F1+2 levels were at all times lower than control levels in TFPI boost group (p < 0.0001).

Conclusions: Heparin-induced TFPI elevation attenuates TF-mediated thrombin generation. Early heparin administration prior to the emergence of plasma TF may represent a novel strategy for controlling thrombin generation by the extrinsic coagulation pathway during CPB.
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http://dx.doi.org/10.1111/jocs.12254DOI Listing
January 2014

Cardiac sympathetic activity assessed by heart rate variability indicates myocardial ischemia on cold exposure in diabetes.

Ann Vasc Dis 2013 5;6(3):583-9. Epub 2013 Sep 5.

School of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.

Measurement of heart rate variability (HRV) is a non-invasive technique that can be used to investigate functioning of the autonomic nervous system, especially the balance between sympathetic and vagal activities. It is reported that dilatation of coronary microcirculation by augmentation of sympathetic nerve activity (SNA) caused by cold exposure was impaired in diabetes. The question of whether or not SNA in HRV could respond to coronary ischemia was evaluated by cold exposure in diabetic rats. It was found that diabetes with weight loss significantly increased SNA both in baseline and cold exposure, compared with control. A correspondence was also found with coronary ischemia. It can be concluded that measurement of HRV may provide useful information regarding the coronary risk of cold exposure in diabetes. (English translation of J Jpn Coll Angiol 2012; 52: 295-301).
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http://dx.doi.org/10.3400/avd.cr.13-00064DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3793179PMC
October 2013

Nontraditional placement of an implantable cardioverter-defibrillator in a heterotaxy patient after the completion of total cavopulmonary connection.

J Artif Organs 2013 Dec 1;16(4):495-7. Epub 2013 Jun 1.

Department of Cardiovascular Surgery, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, 305-8577, Japan.

A 15-year-old boy with heterotaxy syndrome developed a prolonged QT interval and intractable torsade de pointes after the administration of sodium channel blockers for atrial tachyarrhythmia. Although this situation called for the placement of an implantable cardioverter-defibrillator, a conventional transvenous approach was not available since the patient had previously undergone a nonfenestrated extracardiac total cavopulmonary connection. We were urged to carry out the surgical placement of an epicardial lead for an implantable cardioverter-defibrillator using a single coil transvenous shock lead through re-do midline sternotomy. Here we describe the details of this nontraditional surgical procedure for the placement of a lead for an implantable cardioverter-defibrillator in a case without venous access into the heart.
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http://dx.doi.org/10.1007/s10047-013-0714-4DOI Listing
December 2013

Effects of landiolol hydrochloride on intractable tachyarrhythmia after pediatric cardiac surgery.

Ann Thorac Surg 2013 May 15;95(5):1685-8. Epub 2013 Mar 15.

Department of Cardiovascular Surgery, University of Tsukuba, Ibaraki, Japan.

Background: While β-blockers can be effective in controlling tachyarrhythmias after pediatric cardiac surgery, a negative inotropic influence sometimes complicates their use. Landiolol hydrochloride is a novel, ultra-short-acting β-blocker recently developed in Japan. The drug has higher β1:β2 selectivity ratio and a less negative inotropic effect. This study retrospectively evaluates the efficacy and safety of landiolol in the management of tachyarrhythmias after pediatric cardiac surgery.

Methods: A retrospective analysis was performed on 312 consecutive patients undergoing surgery for congenital heart disease. Twelve patients were treated with landiolol for critical tachyarrhythmia. The mean age of patients was 28.7 ± 10.6 months. Five junctional ectopic tachycardia, 2 atrial flutters, 1 paroxysmal supraventricular tachycardia, 1 atrial fibrillation, 1 atrioventricular reciprocating tachycardia with Wolff-Parkinson-White syndrome and 2 excessive sinus tachycardia were treated.

Results: The mean loading and maintenance doses were 11.3 ± 4.0 and 6.8 ± 0.9 μg/kg per minute, respectively. Rate control was achieved in all patients. Landiolol reduced the heart rate from 169.7 ± 11.4 to 127.7 ± 7.5 beats per minute (p < 0.05) while blood pressure did not significantly change. Tachyarrhythmias were converted to sinus rhythm in 70.0% of the cases and the average time needed to achieve heart rate reduction was 2.3 ± 0.5 hours.

Conclusions: Landiolol was efficacious in treating tachyarrhythmia in pediatric cardiac surgery. The desired negative chronotropic effect was achieved without significant hemodynamic compromise. The ultra-short half-life of landiolol provided rapid dose manipulation. This study suggests that landiolol is a promising option for the management of postoperative tachyarrhythmias in pediatric patients.
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http://dx.doi.org/10.1016/j.athoracsur.2013.01.057DOI Listing
May 2013

Using synchrotron radiation angiography with a highly sensitive detector to identify impaired peripheral perfusion in rat pulmonary emphysema.

J Synchrotron Radiat 2013 Mar 8;20(Pt 2):376-82. Epub 2013 Feb 8.

Graduate School of Comprehensive Human Science, Department of Thoracic and Cardiovascular Surgery, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, Japan.

Owing to limitations in spatial resolution and sensitivity, it is difficult for conventional angiography to detect minute changes of perfusion in diffuse lung diseases, including pulmonary emphysema (PE). However, a high-gain avalanche rushing amorphous photoconductor (HARP) detector can give high sensitivity to synchrotron radiation (SR) angiography. SR angiography with a HARP detector provides high spatial resolution and sensitivity in addition to time resolution owing to its angiographic nature. The purpose of this study was to investigate whether this SR angiography with a HARP detector could evaluate altered microcirculation in PE. Two groups of rats were used: group PE and group C (control). Transvenous SR angiography with a HARP detector was performed and histopathological findings were compared. Peak density of contrast material in peripheral lung was lower in group PE than group C (p < 0.01). The slope of the linear regression line in scattering diagrams was also lower in group PE than C (p < 0.05). The correlation between the slope and extent of PE in histopathology showed significant negative correlation (p < 0.05, r = 0.61). SR angiography with a HARP detector made it possible to identify impaired microcirculation in PE by means of its high spatial resolution and sensitivity.
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http://dx.doi.org/10.1107/S090904951300040XDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3943542PMC
March 2013

Significant correlation between endothelial nitric oxide synthase (eNOS) expression and alveolar repair in elastase-induced rat pulmonary emphysema.

Surg Today 2013 Mar 22;43(3):293-9. Epub 2012 Aug 22.

Department of Thoracic Surgery, Graduate School of Comprehensive Human Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.

Background And Purpose: Angiogenic factors, such as endothelial nitric oxide synthase (eNOS), are thought to play an important role in the repair of pulmonary emphysema (PE); yet, the correlation of the factors involved has not been investigated. We conducted this study to clarify the positive correlation between eNOS expression and alveolar repair in PE recovery.

Methods: We used elastase to induce PE in rats, which were divided into Groups A (Control), B (G-CSF), C (PE) and D (PE + G-CSF). G-CSF was injected for 12 days, 4 weeks after which the alveolar walls, arterioles, and angiogenic factors including eNOS were examined histopathologically and by western blotting.

Results: In comparing Groups A, B, C, and D, the alveolar density was 2.4 ± 0.2, 2.4 ± 0.1, 1.8 ± 0.1, 2.5 ± 0.1 per 100 μm(2), respectively (C vs. others; p < 0.00001) and the number of arterioles was 4.5 ± 1.0, 5.6 ± 0.6, 3.2 ± 0.5, 5.5 ± 0.7/mm(2), respectively (C vs. others; p < 0.05). Immunohistochemical staining (IHC) revealed different eNOS expression in Group D versus Group C (p < 0.0001) and western blotting revealed different eNOS, VEGF, and FLT-1 expression in Group D versus Group C (p < 0.01, p < 0.05, p < 0.001), reflecting the contribution of angiogenesis to PE repair. eNOS showed a significantly positive correlation to alveolar density and arteriole repair.

Conclusion: Alveolar repair was correlated positively with eNOS expression by vascular regeneration in elastase-induced rat PE.
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http://dx.doi.org/10.1007/s00595-012-0293-7DOI Listing
March 2013

Isolated cardiac involvement of B-cell acute lymphoblastic leukemia mimicking acute myocardial infarction with persistent broad ST-segment elevation.

Circulation 2012 Jun;125(22):e979-82

Cardiovascular Division, Institute of Clinical Medicine, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.

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http://dx.doi.org/10.1161/CIRCULATIONAHA.111.050930DOI Listing
June 2012

[Cooperation between the Department of Cardiovascular Surgery in University of Tsukuba and Cho-Ray Hospital, Ho-Chi-Minh City, Vietnam--for an attractive collaboration in international medical education].

Nihon Geka Gakkai Zasshi 2012 Mar;113(2):252-6

Department of Cardiovascular Surgery, Faculty of Medicine, University of Tsukuba, Japan.

The Department of Cardiac Surgery in Cho-Ray Hospital, Ho-Chi-Minh city stands for a representative high volume center in the south of Vietnam. In the department about 1,200 cases of open-heart surgery are performed in a year. In next era, they wish to improve their surgical quality, focusing on complex and low-weight congenital cases, mitral repair, maze operation and off-pump CABG. Since 2008, University of Tsukuba has started to collaborate with many departments in Cho-Ray Hospital as a project of international medical educations in Global 30, and has been establishing meaningful activities in the Department of Cardiac Surgery as well. We keep providing opportunities for education, research and training for young Vietnamese doctors and investigators as much as possible both in Cho-Ray Hospital and University of Tsukuba with some financial support. We believe that our steady collaboration with Cho-Ray Hospital will bring certain developments not only for Vietnamese but for ourselves.
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March 2012

Appropriate route selection for extracardiac total cavopulmonary connection in apicocaval juxtaposition.

Ann Thorac Surg 2012 Jul 10;94(1):179-84. Epub 2012 May 10.

Department of Cardiovascular Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.

Background: A malpositioned heart with apicocaval juxtaposition may complicate the management of patients with functional single ventricles when total cavopulmonary connection is performed. We reviewed our experience with extracardiac total cavopulmonary connection in patients with apicocaval juxtaposition with a special focus on route selection and outcomes.

Methods: Of 68 patients who underwent extracardiac total cavopulmonary connection at our hospitals, 10 patients with apicocaval juxtaposition were included in this study. The mean follow-up was 40 ± 28 months. Patient demographics were compared with data on patients without apicocaval juxtaposition.

Results: The age at operation was 8 ± 7 years. We carefully chose conduit routes to create satisfactory fluid dynamics. The conduit was placed between the inferior vena cava and the ipsilateral pulmonary artery in 2 patients, and the conduit crossed midline in 8 patients. The mean postoperative pulmonary artery pressure was 13 ± 2 mm Hg. The surgical and postoperative data were not significantly different when compared with the patients without apicocaval juxtaposition. There were no conduit-related early or late complications except for 1 patient who had poor ventricular function.

Conclusions: Extracardiac total cavopulmonary connection in apicocaval juxtaposition can be carried out with favorable midterm outcomes. The route between the inferior vena cava and the contralateral pulmonary artery should be the primary choice when the relevant pulmonary artery is in good shape. Care must be taken in regard to critical conduit oppression by the ventricle in cases with large ventricular volume or poor ventricular function.
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http://dx.doi.org/10.1016/j.athoracsur.2012.03.026DOI Listing
July 2012

Inhibition of protein kinase C β ameliorates impaired angiogenesis in type I diabetic mice complicating myocardial infarction.

Circ J 2012 8;76(4):943-9. Epub 2012 Feb 8.

Department of Cardiovascular Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.

Background: In recent studies, the inhibition of protein kinase C (PKC) β has been shown to improve diabetic vascular complications. However, the effect on angiogenesis in myocardial ischemia with diabetes mellitus (DM) is still unknown.

Methods And Results: Mice were divided into 3 groups: control, DM and DM+PKC-I groups (n=8, respectively). In the DM and DM+PKC-I groups, diabetes was induced by streptozotocin (STZ) (1.5mg/body i.p.) for 5 days. Next, left anterior descending artery (LAD) ligation was performed in all groups. In the DM+PKC-I group, PKC β inhibitor (Cat. No. 539654; 10 nmol/L) was administered from days 1 to 10. After 4 weeks of LAD ligation, the animals were killed. Microvascular density was significantly improved by PKC β inhibitor (control: 87.9±5.2/high-power field (HPF); DM: 51.4±6.9/HPF; PKC-I: 80.3±4.9/HPF; P<0.05). Expression of both vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS), which was decreased in the DM group, were significantly improved by inhibition of PKC β [VEGF (DM: 0.36±0.11-fold and DM+PKC-I: 0.77±0.07-fold vs. control), eNOS (DM: 0.35±0.06-fold and DM+PKC-I: 0.73±0.08-fold vs. control); both P<0.05)].

Conclusions: Inhibition of PKC β ameliorated impaired angiogenesis by hyperglycemia in STZ-induced DM mice complicated by myocardial infarction. These results suggest a new possible indication of PKC β inhibitor for myocardial ischemia with DM.
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http://dx.doi.org/10.1253/circj.cj-11-0881DOI Listing
June 2012

Concealed infective endocarditis associated with subaortic left ventricular aneurysm.

Thorac Cardiovasc Surg 2012 Dec 3;60 Suppl 2:e9-12. Epub 2012 Jan 3.

Department of Cardiovascular Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.

We describe a case of subaortic left ventricular aneurysm with concealed infective endocarditis. The patient, who was diagnosed with aortic regurgitation and a subaortic left ventricular aneurysm, did not exhibit any evidence of infective endocarditis preoperatively. However, histopathological examination after an aortic valve replacement revealed neutrophil infiltration in the resected aneurysm. One year postoperatively, the infection recurred and an aortic root replacement was performed.
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http://dx.doi.org/10.1055/s-0031-1295583DOI Listing
December 2012

Prospective intraindividual comparison of unenhanced magnetic resonance imaging vs contrast-enhanced computed tomography for the planning of endovascular abdominal aortic aneurysm repair.

J Vasc Surg 2012 Mar 21;55(3):679-87. Epub 2011 Nov 21.

Department of Radiology, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan.

Objective: This study clarified whether unenhanced magnetic resonance imaging (MRI) is an alternative to contrast-enhanced computed tomography (CT) for aortoiliac arterial measurement before endovascular abdominal aortic aneurysm repair (EVAR).

Methods: The institutional review board approved this prospective study. Twenty patients being considered for EVAR underwent MRI using a steady-state free-precession sequence in a 1.5-T system and contrast-enhanced CT within 4 weeks of each other. Two independent observers reviewed MRI and CT in random order using vessel analysis software and measured seven diameters, four lengths, and the angle of the aortoiliac arteries. The intermodality, interobserver, and intraobserver agreements were assessed for each measurement by intraclass correlation coefficients (ICCs) and the Altman-Bland method. Additionally, the observers independently recorded the number of bilateral renal arteries, decided EVAR suitability, and selected the main endograft on each modality.

Results: Intermodality ICCs for observers A and B showed ranges of 0.83 to 0.99 and 0.70 to 0.98; interobserver ICCs for MRI and CT showed ranges of 0.73 to 0.99 and 0.65 to 0.99; and intraobserver ICCs for MRI and CT showed ranges of 0.59 to 0.99 and 0.59 to 0.99. In intermodality, interobserver, and intraobserver comparisons, mean differences in diameters were included within the range -1 to +1 mm, excluding three of seven diameters on CT in interobserver comparison and one of seven on CT in intraobserver comparison. Mean differences in lengths were included within the range -5 to +5 mm, excluding one of four lengths in observer B in intermodality comparison and one of four on MRI and CT in interobserver comparison. All mean differences in angles were included within the range -5° to +5°. Both observers detected all 40 bilateral main renal arteries on MRI and CT. Of the 13 accessory renal arteries, observers A and B detected four (31%) and nine (69%), respectively, on MRI; in contrast, both observers detected 11 (85%) on CT. The observers independently determined that the same seven patients were suitable for EVAR on MRI and CT. Of the seven selected main endografts, seven and six diameters and five and six lengths agreed exactly between MRI and CT for observers A and B, respectively.

Conclusions: Although contrast-enhanced CT remains the gold standard for preoperative EVAR planning, unenhanced MRI with steady-state free-precession sequence can be an alternative modality for patients with contraindications for CT, such as renal impairment, because the intermodality agreement for preoperative measurements is as good as interobserver and intraobserver agreement.
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http://dx.doi.org/10.1016/j.jvs.2011.09.091DOI Listing
March 2012

Surgical repair for rupture of a chronic traumatic thoracic aneurysm 14 years after injury: report of a case.

Surg Today 2012 Jan 10;42(2):191-4. Epub 2011 Nov 10.

Department of Cardiovascular Surgery, Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8575, Japan.

Traumatic thoracic aortic injury is a lethal condition. Because its mortality rate is extremely high in the acute phase, these patients rarely survive long enough for a chronic aneurysm to develop. We herein report a case of surgical repair for a ruptured chronic traumatic thoracic aneurysm. A 32-year-old man, who had been involved in a traffic accident 14 years earlier, was diagnosed with a rupture of a chronic traumatic thoracic aneurysm. Preoperative computed tomography showed that the ruptured aneurysm arose from the aortic isthmus and was accompanied by multiple daughter lesions. He underwent an aorta graft replacement with reconstruction of the left subclavian artery using both a median sternotomy and a left thoracotomy. The surgery was successful and the postoperative course was uneventful. Chronic traumatic thoracic aneurysm is usually a single lesion, and cases with daughter aneurysms have rarely been reported. We include a review of the previous literature and also discuss the etiology of this condition.
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http://dx.doi.org/10.1007/s00595-011-0001-zDOI Listing
January 2012