Nobushige Tamura

Intrathoracic esophageal replacement in the dog with the use of an artificial esophagus composed of a collagen sponge with a double-layered silicone tube

OBJECTIVES Intrathoracic esophageal replacement with an artificial esophagus is considered difficult. We attempted to replace the intrathoracic esophagus with an artificial esophagus composed of a collagen sponge with a double-layered silicone tube and examined the state of host tissue regeneration. METHODS A 5-cm long gap was created in the intrathoracic esophagus in 9 dogs and repaired by interposition of our prosthesis. The dogs were fed only by intravenous hyperalimentation for 28 days. The silicone tube was removed at 29 days after the operation, and oral feeding was reintroduced. RESULTS One dog was put to death at each of the following times: 1, 2, 3, 3, 6, 12, and 24 months after the operation. One dog is still surviving without problems after more than 26 months. One dog died of malnutrition at 10 months. In all dogs, the host regenerated tissue had replaced the resulting gap at the time of silicone tube removal. The mucosa had fully regenerated within 3 months and the glands within 12 months. The process of stenosis and shrinkage was complete within 3 months and did not advance thereafter. The lamina muscularis mucosae were observed as islets of smooth muscle within 12 months. Although the skeletal muscle regenerated close to the anastomoses, it did not extend to the middle of the regenerated esophagus even after 24 months. CONCLUSIONS Use of a collagen sponge with a double-layered silicone tube was shown to be feasible even in the thorax and to allow the regenerated host tissue, consisting of the mucosa, glands, and lamina muscularis mucosae, to replace the esophageal gap.

Artificial trachea and long term follow-up in carinal reconstruction in dogs.

We have already reported “del” successful carinal reconstruction of the trachea with an observation period of 1 – 2 years. In this study, we evaluate the long-term safety and efficacy of the reconstruction after 5-years of follow-up. The Y-shaped Marlex® mesh tube was reinforced with a polypropylene spiral and coated with atelocollagen made from porcine skin. The prosthesis was 60 mm long with an outer diameter of 18 mm. Replacement of the tracheobronchial bifurcation was preformed through a right thoracotomy in a beagle dog. Bronchoscopical examination and sampling of the tracheal epithelium was performed periodically to check the function of cilia. The implanted prothesis was promptly infiltrated by the surrounding connective tissue and completely incorporated by the host trachea and bronchus. Bronchoscopically, sufficient epithelization was confirmed from the upper to the lower site of anastomosis. After 5 years neither stenosis nor dehiscence was observed. In spite of there being mesh-exposure at the luminal surface, the dog had no clinical symptoms until sacrifice for pathological examination. The bent frequency of the cilia was maintained within the normal range, indicating “del” functional recovery of the regenerating airway. Our tracheal prosthesis is promising for clinical “del” repair of the tracheobronchial bifurcation.

Coronary artery bypass surgery is superior to percutaneous coronary intervention with drug-eluting stents for patients with chronic renal failure on hemodialysis.

BACKGROUND Improvements in the results of percutaneous coronary intervention (PCI) with drug-eluting stents (DES) have been extending their use in patients with all forms of coronary artery disease. The purpose of this study was to compare the midterm clinical results of coronary artery bypass surgery (CABG) and PCI with DES in patients with chronic renal failure on hemodialysis. METHODS From January 2002 to December 2006, 29 patients underwent CABG, and 75 patients underwent PCI with DES. For CABG, 24 patients had off-pump surgery. The mean follow-up was 32.0 +/- 22.0 months for CABG and 23.5 +/- 14.8 months for PCI. Survival, cardiac death, major adverse cardiac events (cardiac death, myocardial infarction, revascularization), and target lesion revascularization were analyzed using the Kaplan-Meier method. RESULTS Preoperative characteristics and risk factors were compatible between the groups except for the European System for Cardiac Operative Risk Evaluation (7.3 +/- 2.7 for CABG and 5.0 +/- 2.4 for PCI, p < 0.0001) and the presence of a left main trunk lesion (53.3% for CABG and 18.7% for PCI). Thirty-day mortality was 3.3% for CABG and 4.0% for PCI. The 2-year survival rate was 84.0% for CABG and 67.6% for PCI (p = 0.0271). The cardiac death-free curve at 2 years was 100% for CABG and 84.1% for PCI (p = 0.0122). The major adverse cardiac events-free rate at 2 years was 75.8% for CABG and 31.5% for PCI (p < 0.0001). During the follow-up period, there were 6 late deaths in the CABG group and 27 late deaths (including 6 sudden deaths) in the PCI group. CONCLUSIONS Coronary artery bypass grafting was superior to PCI with DES in patients with chronic renal failure on hemodialysis in terms of long-term outcomes for cardiac death, major adverse cardiac events, and target lesion revascularization. The DES carried a higher risk for sudden death, which might be associated with stent thrombosis.

Surgical Treatment for Postinfarction Left Ventricular Free Wall Rupture

BACKGROUND Left ventricular (LV) free wall rupture is a catastrophic complication after acute myocardial infarction. The optimal therapeutic strategy is controversial and the midterm results are unknown. METHODS Between June 1993 and May 2006, 32 patients with an average age of 73 years (range, from 55 to 96 years) were surgically treated for LV free wall rupture. Sutureless technique (gluing autologous patch to the tear) was applied in all patients. RESULTS The interval between acute myocardial infarction and the rupture was 33 +/- 42 hours and the interval between the rupture and the operation was 3.6 +/- 2.6 hours. Preoperatively, cardiopulmonary resuscitation was performed in eight cases. Percutaneous cardiopulmonary support was placed in six cases and intraaortic balloon pumping in 20 cases preoperatively. The in-hospital mortality was 15.6%. Two patients died of rerupture within ten days. While there was no rerupture during the follow-up period, five patients developed dyskinetic LV aneurysm and one patient developed LV pseudoaneurysm. CONCLUSIONS The sutureless technique is a simple and effective option for the surgical treatment for LV free wall rupture. The preoperative moribund condition was highly associated with the operative mortality.

A new acellular vascular prosthesis as a scaffold for host tissue regeneration

OBJECTIVE In situ tissue engineering using acellular xenografts is a new approach to autologous tissue regeneration. In the present study, we analyzed a new regeneration scaffold comprised of xenogenic acellular vessels in a dog model. DESIGN OF STUDY AND RESULTS Xenogenic vascular conduits of porcine carotid arteries were acellularized by a 48-hour detergent incubation to extract all the cell components of the graft. The acellularisation procedure resulted in a complete removal of all cells. After this procedure, heparinization was performed sequentially to induce antithrombogenicity in the graft. The burst pressure of the graft was tested. The bursting pressure of the fresh vessels was 2.83 +/- 0.56 x 10(3) mmHg (377 +/- 75kPa, n = 6). After detergent treatment, the bursting pressure of the grafts was 2.50 +/- 0.48 x 10(3) mmHg (334 +/- 63 kPa, n = 6); after heparinization, it was 3.44 +/- 0.38 x 10(3) mmHg (459 +/- 51 kPa, n = 5). In vivo function was tested in a dog model by transplantation to the abdominal artery. By 18 weeks, endothelial cells were aligned as in normal, healthy artery over the surface of the entire graft. Fibroblasts and macrophages had infiltrated the graft from both inside and outside. The neointima contained normal layers of smooth muscle cells, which were identified by anti alpha-smooth muscle fiber antigen staining. CONCLUSIONS The acellular heparinized xenograft has sufficient mechanical properties and was successfully replaced with host tissue, and is thus a promising new type of vascular prosthesis.

Intrathoracic esophageal replacement with a collagen sponge-silicone double layer tube : Evaluation of omental-pedicle wrapping and prolonged placement of an inner stent

In a previous study, we replaced a 5 cm gap created in the canine intrathoracic esophagus with an artificial esophagus. However, although newly formed esophageal tissue subsequently bridged the gap, mild stenosis occurred, and this seemed to be caused by inadequate regeneration of the skeletal muscle. In the present study, we evaluated whether omental pedicle wrapping (OMPx) of the prosthesis could promote tissue regeneration and whether prolonged retention of the silicone tube within the prosthesis could prevent stenosis. A gap was created in 14 dogs, and the defect was repaired by our prosthesis. OMPx was performed in 5 of the 14 dogs (OMPx group) but not in the rest (control group). The silicone tube was retained for 4 weeks in the control group and for 8 weeks in the OMPx group. All of the dogs in the control group survived for more than 3 months, except for those that were killed. Four dogs in the OMPx group died within 3 months, one caused by perforation at 7 months. Only the thin epithelial and submucosal layer regenerated in the OMPx group. OMPx is not effective for promoting tissue regeneration, and prolonged retention of the silicone tube interrupts epithelial regeneration.

Long-Term Survival After Coronary Arterial Grafts in Patients With End-Stage Renal Disease

BACKGROUND Bilateral internal thoracic artery (BITA) grafting is known to improve the long-term survival after coronary artery bypass grafting (CABG). However, there are few reports regarding the efficacy of BITA grafting in end-stage renal disease (ESRD) patients. This study investigates the potential benefits of BITA grafting in ESRD patients. METHODS One hundred thirty ESRD patients dependent on chronic hemodialysis underwent isolated CABG in the Kumamoto Central Hospital from 1988 to 2009. The early results and long-term outcomes in 49 patients using BITA (BITA group) were compared with 81 patients using a single ITA (SITA group). The mean follow-up time was 5.2 +/- 3.8 years. RESULTS The mortality rate was 4.9% for the SITA group and 4.1% for the BITA group (p = 0.8215). No differences were seen for the incidence of mediastinitis or a rethoracotomy for bleeding. The 3-year, 5-year, 7-year, and 10-year survival rates in the SITA group were 79.6%, 62.5%, 43.6%, and 22.6%, respectively. The corresponding survival rates in the BITA group were 76.0%, 61.9%, 58.8%, and 33.2%, respectively. There were no statistical differences in survival (p = 0.1636), freedom from cardiac death (p = 0.3205), or freedom from cardiac events (p = 0.4071). In ESRD patients without diabetes mellitus, BITA grafting improves the outcomes concerning cardiac events (p = 0.0143). CONCLUSIONS After a long-term follow-up, CABG with BITA grafts showed no advantages in the long-term outcomes among ESRD patients. However, for ESRD patients without diabetes mellitus, BITA grafting may provide more promising long-term outcomes.

Preoperative evaluation of patients with liver cirrhosis undergoing open heart surgery

ObjectiveClinical outcomes after open heart surgery in patients with liver cirrhosis are not satisfactory. For evaluating hepatic function, the Child-Pugh classification has been widely used. It has been reported that open heart surgery can be performed safely in patients with mild liver cirrhosis. In this study, we examined the clinical outcomes after open heart surgery in patients with liver cirrhosis and evaluated the usefulness of the Child-Pugh classification.MethodsThere were 12 liver cirrhosis patients who underwent open heart surgery between January 2002 and December 2006 at our institution. The severity of cirrhosis was graded according to the Child-Pugh classification. We reviewed clinical outcomes, such as postoperative mortality and morbidity, and tried to determine the risk factors. Finally, we assessed the usefulness of the Child-Pugh classification.ResultsSix patients were classified as having Child class A, and the other six patients were classified as B. The overall mortality of group A was 50%, and that of group B was 17%. Postoperative major morbidities occurred in half of the patients of Child class A and in all of the patients of Child class B. Patients who experienced major morbidities had markedly lower levels of serum cholinesterase (106 ± 46 vs. 199 ± 72 IU/l; P = 0.02) and lower platelet level (7.5 ± 2.9 vs. 11.9 ± 3.6 × 104/μl; P = 0.04).ConclusionThe mortality and morbidity rates were high even in the Child class A patients. The Child classification may be an insufficient method for evaluating hepatic function. We have to assess other factors, such as the serum cholinesterase level or the platelet count.

Modified partial aortic root remodeling in acute type A aortic dissection

Emergency surgery for acute type A dissection is extremely difficult when the sinuses of Valsalva are widely dissected. Indications for the various proposed surgical approaches are controversial. Here, we describe modified partial aortic root remodeling to overcome bleeding. We retrospectively reviewed 13 consecutive patients who underwent the following operative procedure. We did not resect the sinus but sutured a U-shaped Dacron patch to the inside of the sinus to reinforce the dissected weakened wall. The indications for reconstruction of the aortic root with this technique are extension of an intimal tear into a sinus, a fully dissected sinus as far as the level of the aortic annulus or mild annuloaortic ectasia. One patient died of multiorgan failure. No patient had more than mild aortic regurgitation. Mean follow-up duration was 22 months and there was no late death. Two patients underwent repeated surgery due to graft infection and redissection. Our modified partial aortic root remodeling technique might be a useful surgical procedure if one or two Valsalva sinuses are affected in type A acute aortic dissection.

An Experimental Model of Stanford Type B Aortic Dissection

PURPOSE To create an experimental model of aortic dissection with a long-lasting patent false lumen as a proper animal model for development of less-invasive treatment for aortic dissection. MATERIALS AND METHODS Fifteen adult beagle dogs (weight, 10-12 kg) were used. The descending aorta was exposed by a left thoracotomy at the sixth intercostal space. The entry for the aortic dissection was created surgically just distal to the origin of the left innominate artery and the reentry was 5 cm distal to the entry point. Normal saline solution was injected into the aortic wall (ie, media) between these two points to create the dissection. The dogs were followed up at 1 day, 3 months, 1 year, and 2 years. RESULTS All 12 surviving dogs had completely patent true and false lumina without any thrombi. Microscopic examination showed that the dissection was created in the tunica media layer, making it identical to aortic dissection in humans. Color Doppler imaging confirmed the patency of the true and false lumina and the relatively narrowed true lumen. CONCLUSION In this canine model of aortic dissection, the false lumen has excellent long-term patency and the dissection plane is histologically similar to that in human aortic dissection. This model may contribute to the development of new treatments for Stanford type B aortic dissection.