Hiroji Akimoto

Gene therapy for donor hearts: ex vivo liposome-mediated transfection.

OBJECTIVE Liposomes may be an appropriate transfection vehicle for transplanted hearts, avoiding the use of viruses in immunosuppressed hosts and allowing transfection of nondividing cells. To study whether liposome-mediated transfection could be accomplished during transplantation, we used a liposome-reporter gene system in a rabbit model of allograft cardiac transplantation. METHODS After aortic crossclamping, Stauffland donor hearts were injected with 10 ml Stanford cardioplegic solution; then a 1.3 to 2.0 mg/kg dose of chloramphenicol acetyl transferase in 1:1 deoxyribonucleic acid-liposome complexes was injected proximal to the aortic crossclamp for coronary artery perfusion. The hearts were transplanted into New Zealand White rabbit recipients in the heterotopic cervical position (n = 11 transplants). Recipients were sacrificed at 24 hours. Myocardial specimens (right and left ventricles) and vascular specimens (epicardial coronary artery, aortic root, and coronary sinus) from both the transplanted and native hearts were analyzed for chloramphenicol acetyl transferase protein by means of the enzymatic liquid scintillation assay (counts per minute per milligram of total protein). RESULTS In the recipient, myocardial chloramphenicol acetyl transferase activity was significantly greater in treated donor hearts (mean 4.6 x 10(5) cpm/mg +/- 1.1 x 10(5) [standard error]) than in native hearts (mean 4.1 x 10(2) cpm/mg +/- 72 [standard error], p < 0.01, Mann-Whitney U test). In treated donor hearts, right and left ventricular specimens, as well as apical and basal myocardial specimens, were transfected equally. Chloramphenicol acetyl transferase activity in vascular specimens also indicated transfection (mean 5.4 x 10(5) cpm/mg +/- 2.5 x 10(5) [standard error]). Chloramphenicol acetyl transferase activity in the coronary sinus was comparable with that in the coronary arteries, which suggests that liposomes can transverse the coronary capillary beds. CONCLUSIONS These findings demonstrate that ex vivo transfection of donor hearts with a liposome-reporter gene system results in significant in vivo expression of the transfected gene product after cardiac transplantation. Genetic alteration of myocardium and cardiac vasculature has potential clinical applications in the prevention of posttransplantation rejection, ischemia-reperfusion injury, and both transplant and nontransplant coronary artery disease.

Aortic arch aneurysm repair using selective cerebral perfusion

Seventy-seven patients underwent aortic arch aneurysm repair using selective cerebral perfusion from January 1987 to August 1992. Early and long-term results and preoperative and postoperative cerebral function were evaluated. Cerebral function was assessed by the mini mental state-Himeji test and the Wechsler adult intelligence scale. Thirty-six patients had true aneurysms, and 41 had dissection. Hospital mortality for true and dissecting aneurysms was 19.4% and 7.3%, respectively. The 5-year actuarial survival rates for true and dissecting aneurysms were 59.0% and 65.3%, respectively (not significant). There were no significant differences in test scores before or after operation. Repair or replacement of the aortic arch using selective cerebral perfusion is a safe procedure with acceptable hospital mortality.

Protection of the brain during hypothermic perfusion

The adequacy of the circuits for brain perfusion has been explored by hemodynamic assessment using the ability of the brain to autoregulate blood flow as an indicator, and by morphologic observation using carbon black or Evans blue infusion into the brain perfused antegradely or retrogradely. It is concluded that the safe pressure of cerebral perfusion needed to maintain cerebral integrity is between 40 and 50 mm Hg in both normothermic and hypothermic perfusions, a pressure that can be generated by nonpulsatile pump flows through the pump greater than 40 mL.kg-1 x min-1. Morphologic studies revealed development of focal infarctions in the brain and destruction of the blood-brain barrier by retrograde cerebral perfusion. The retrograde approach, therefore, is definitely inferior to the antegrade method. Antegrade perfusion for 90 minutes, however, produced minimal cerebral edema, suggesting the need for further improvement even in techniques of antegrade perfusion.

Quantitative analysis of cardiac 3-L-nitrotyrosine during acute allograft rejection in an experimental heart transplantation.

BACKGROUND Recent studies have shown that nitric oxide interacts with superoxide to form peroxynitrite, a potent oxidant that modifies cellular proteins producing 3-L-nitrotyrosine (N-Tyr). This study was designed to evaluate N-Tyr quantitatively with high-performance liquid chromatography (HPLC) during cardiac allograft rejection. METHODS Rat transplanted hearts (allogeneic or syngeneic grafts) were examined with HPLC analysis, immunohistochemistry for N-Tyr, and histological studies on 0, 1, 3, and 7 days after transplantation. RESULTS No histological rejection was found in syngeneic grafts, or day 0 or 1 allografts. HPLC demonstrated that N-Tyr in allografts increased on day 1 and continued to increase through day 7, while N-Tyr was not detected in any syngeneic grafts. Immunostaining of the allografts did not show N-Tyr on day 1. CONCLUSION These results demonstrate that N-Tyr shows a time-dependent accumulation in cardiac allografts during acute rejection. N-Tyr detection using HPLC may be an useful maker for early diagnosis of acute rejection before pathological rejection occurs.

Use of cuffed anastomosis in total aortic arch replacement.

The distal aortic anastomosis portion of the total arch surgery remains technically complex especially in cases in which an aortic arch aneurysm extends below level of carina. We present the cuffed anastomosis that overcomes this difficulty. We applied this technique in 49 patients of elective total aortic arch aneurysm repair using selective cerebral perfusion from 1996 to 2001. Hospital mortality was 2%.

Epidural cooling for regional spinal cord hypothermia during most or all of descending thoracic or thoracoabdominal aneurysm repair

Abstract Purpose: Hypothermia has some protective effect against ischemia of the spinal cord in thoracoabdominal aneurysm repair. Its method is divided into systemic or regional cooling. Several experimental studies of the regional cooling of the spinal cord have been performed, however, clinical reports are few. The purpose of this study is to evaluate the effect and safety of perfusion cooling of the epidural space during thoracic or thoracoabdominal aortic replacement. Methods: Between January 1998 to June 2001 37 patients (True aneurysm: 18 patients, type B aortic dissection: 19 patients) underwent thoracic or thoracoabdominal aortic replacement with an aid of epidural perfusion cooling. The age ranged from 23 to 78 years old with a mean age of 61 years old. Separate perfusion of upper and lower body was used in all cases. Temperature was lowered to around a 31°C or 32°C. In cases where proximal cross-clamping was danger, deep hypothermic circulatory arrest was used. Results: Ten patients underwent most or all of descending thoracic aneurysm repair with no spinal cord injury and hospital death. Number of patients of the Crawford type I, type II, and type III were 14, 8 and 5 patients, respectively. One Crawford type II patient was complicated with postoperative spinal cord injury (2.7%). There was one hospital death (2.7%) in Crawford type III. The mean epidural cooling time was 150 minutes, and mean infusion volume of cold saline was 981 cc. The mean lowest cerebrospinal fluid (CSF) temperature was 24.3°C, and mean temperature differences between nasopharynx and CSF was 6.3°C. Conclusion: Perfusion cooling of the epidural space during most or all of the descending thoracic or thoracoabdominal aneurysm repair was effective in reducing postoperative spinal cord injury and a safe method in clinical situations.

Safety and clinical benefits of transsubxiphoidal left ventricular puncture.

We performed a transsubxiphoidal LV puncture (TSLVP) to evaluate left ventricular function in 21 patients with both mechanical prosthetic aortic and mitral valves and successfully obtained hemodynamic information on each patient. Analyzing cardiac hemodynamic information and ventriculographic findings obtained with TSLVP, we concluded that seven of the patients required repair of their prosthetic valves. Five of these seven patients agreed to replacement of their valves, whereas two did not. TSLVP was performed adequately and safely without severe complications, suggesting that this maneuver is easier than that of transapical LV puncture and should be recommended for the assessment of left ventricular hemodynamic functions instead of the transapical LV puncture, especially in patients requiring replacement of two valves. Cathet Cardiovasc Intervent 2002;55:58–65.

Development of a method to construct three-dimensional finite element models of thoracic aortic aneurysms from MRI images

Most patients die when thoracic aortic aneurysms rupture. In order to avoid the ruptures, the aneurysms are replaced with aortic prostheses when their maximum diameter exceeds 5 cm. Because this criterion is based on the experiences, some aneurysms rupture even if the diameters are smaller than this criterion. To treat the aneurysm properly, it is necessary to find out the new criterion. The rupture is thought to have a close relationship with the stress in the wall. Hence, there is much research about the stress, but this research uses the straight tube model. The model shape does not seem appropriate to a thoracic aorta shape. Hence, we developed the method to construct three-dimensional finite element models of thoracic aortic aneurysms from MRI images.

Cryopreserved aortic homograft replacement in 3 patients with noninfectious inflammatory vascular disease

OBJECTIVE Although mechanical prosthetic heart valves are most commonly used for aortic valve replacement in patients with aortic regurgitation due to noninfectious inflammatory vascular disease, postoperative perivalvular leakage and/or detachment of the prosthetic valve occurs due to the fragility of the aortic annulus. Aortic root replacement with cryopreserved homografts is reported to be useful in such patients. METHODS Three patients having aortic regurgitation associated with severe long standing noninfectious inflammatory vascular disease-2 patients with Takayasus arteritis and 1 patient with Behçet disease--had the aortic root replacement by a cryopreserved aortic homograft valve and conduit. RESULTS All surgery was successful and the postoperative course uneventful. Echocardiography showed neither aortic regurgitation nor graft detachment at 6-39 months after operation. CONCLUSIONS Homograft valve and conduit replacement is appropriate in patients with aortic regurgitation associated with noninfectious inflammatory vascular disease, with mid-term results favorable.

Concomitant Replacement of the Aortic Root And Aortic Arch With or without Secondary Thoracoabdominal Aorta Replacement

OBJECTIVES Extensive aortic replacement, such as concomitant aortic root and arch replacement, thoracoabdominal aortic repair, and complete thoracic aorta replacement, remains controversial. We studied surgical morbidity and mortality in patients undergoing concomitant aortic root and arch replacement, and those undergoing secondary replacement of the thoracoabdominal aorta after this preceding procedure. SUBJECTS AND METHODS Between January, 1987 and March 1999, 21 patients (mean age: 52 years) underwent concomitant aortic root and arch replacement involving 3 surgical procedures--aortic root replacement with composite graft and arch (n = 12), aortic root replacement with valve sparing and arch (n = 4), or aortic root replacement with composite graft and arch and elephant trunk (n = 5). RESULTS Overall hospital mortality was 4.8%. Six patients (mean age: 42 years) underwent secondary thoracoabdominal aorta replacement after the concomitant root and arch procedure. The mean time until secondary surgery was 9.5 months. There was 1 hospital death. CONCLUSION Concomitant replacement of the aortic root and arch, or secondary replacement of the thoracoabdominal aorta after concomitant root and arch replacement can be conducted with low surgical morbidity and mortality.