Biomedical subjects

G Zünd

Publications and source records attributed to G Zünd.

77 records · Page 5Linked to original sources

PubMedDate not supplied

Modified technique for heterotopic rat heart transplantation under cardioplegic arrest.

The development of microsurgical techniques offers a valuable opportunity to use small animals for experimental studies of vascularized organ transplants. Availability of inbred strains, natural resistance to infection, and economy make the rat an ideal animal model to investigate the effects of heart transplantation. The recent high interest and substantial laboratory activity with regard to posttransplantory immunological tissue reactions and apoptotic tissue processes led us to optimize transplantation technique by improving myocardial protection during ischemia and thereby minimizing adverse effects of the transplantation procedure itself. Thus the present report details the technique of heterotopic heart transplantation in rats using cardioplegic arrest.

Anastomosis, Surgical↗

PubMedDate not supplied

Approach to the mitral valve through a right thoracotomy in potentially hazardous reoperation.

BACKGROUND: Repeat sternotomy for mitral valve surgery may be hazardous in some patients. A right thoracotomy avoids the densely scarred area beneath the sternum and provides adequate in-line exposure of the mitral valve. METHODS: Between 1994 and 1997, five patients were reoperated for a mitral valve or prosthesis dysfunction through a right thoracotomy. Indications were three second redo-mitral valve surgeries and two first redo, once in a patient with an aortic prosthesis and once in a patient with patent aortocoronary grafts. The operation was performed without clamping the ascending aorta in moderate hypothermic (four patients) or normothermia (one patient). RESULTS: Exposure of the mitral valve for replacement (four patients) or for repair of a paraprosthetic leak (one patient) was optimal in all patients. Resumption of cardiac function occurred rapidly after repair without specific support. Postoperative course was uncomplicated. Blood loss ranged from 300 to 700 mL. Patients were discharged from 7 to 12 days postoperatively. They are in New York Heart Association (NYHA) functional Class I (four patients) and II (one patient), from 3 to 42 months postoperatively. CONCLUSION: Right thoracotomy provides a direct "in the line of vision" access to the mitral valve. Because complete de-airing of the heart is difficult and respiratory function depressed after a right thoracotomy, this approach seems suitable when technical difficulties are expected in sternal reopening.

Adult↗

PubMedDate not supplied

Less invasive surgical treatment of renal cell carcinomas extending into the right heart and pulmonary arteries: surgery for renal cell carcinoma.

BACKGROUND: Radical resection using deep hypothermic circulatory arrest improves the survival of patients with transvenous intracardiac tumor extension of renal cell carcinomas. A less invasive surgical approach avoiding deep hypothermia, circulatory arrest, and cross-clamping of the aorta is presented. METHODS: Between 1987 and 1999, 12 patients (mean age 57+/-8 years) underwent resection of a renal cell carcinoma extending into the right atrium, right ventricle, or pulmonary arteries. After median sterno-laparotomy, normothermic cardiopulmonary bypass is used cannulating the ascending aorta, superior caval vein, and inferior caval vein below the renal veins. The tumor and the corresponding kidney are radically excised, including the renal vein. Tumor fragments from the inferior caval vein, the right heart, and pulmonary arteries are removed either on the fibrillating or beating heart. RESULTS: Operative mortality was 0%. Mean cardiopulmonary bypass time was 53+/-27 minutes (median 36; range 32-110 minutes). Mean blood loss per patient was 1200 mL. Mean duration of postoperative mechanical ventilation was 36+/-12 hours (median 36; range 30-77 hours), mean intensive care stay 5.5+/-5 days (median 3; range 1-48 days), and mean duration of hospitalization 22+/-12 days (median 21; range 10-58 days). All patients were discharged home. Patients with multiple tumor manifestations outside the cardiovascular systems died within 9 months after the operation. CONCLUSIONS: The use of normothermic cardiopulmonary bypass is a less invasive method for radical resection of renal cell carcinoma with intracardiac tumor extension. Radical resection does not improve survival in patients with multiple distant metastases.

Adult↗

PubMedDate not supplied

Heat shock protein upregulation lowers cytokine levels after ischemia and reperfusion.

OBJECTIVE: Studies showed that the expression of heat shock protein 70 (HSP70) by whole-body hyperthermia or warming of the heart is associated with protection against ischemia/reperfusion injury. The aim of this study is to determine a time-related response of HSP70 expression through topical cardiac warming with correlation to cytokine production. METHODS: 30 rats were divided into three groups: no heat shock, heat shocked, and controls. Heat shock was performed with 42 degrees C saline solution applied to the heart for 5, 30, and 60 min. HSP70 and cytokines were measured. RESULTS: Heat shock treated animals showed a 1.2-fold increase after 5 min (NS) in HSP70 expression, a 2.0-fold increase (p < 0.02) after 30 min, and a 2.3-fold increase (p < 0.012) after 60 min compared to controls. The IL-1beta levels decreased from 14.3 pg/ml (normal controls) to 7.1 pg/ml after 5 min, to 1.6 pg/ml after 30 min (p < 0.002), and to 1.4 pg/ ml after 60 min of heat shock treatment (p < 0.002). The TNF-alpha levels also decreased, but not significantly. CONCLUSIONS: Upregulation of HSP70 through this novel method is instant and detectable within hours. The amount of HSP70 expression induced is time dependent, showing an indirect correlation with cytokine levels. These results suggest that the protective effect of HSP70 is immediate and might be explained by reduced cytokine levels. No prior recovery period is needed.

Animals↗

PubMedDate not supplied

Tissue engineering of a bioprosthetic heart valve: stimulation of extracellular matrix assessed by hydroxyproline assay.

Creation of an autologous heart valve by tissue engineering offers a promising approach to cardiac surgery. Although we have demonstrated successful formation of native valve analogous tissue in vitro, hemodynamic competence remains a serious problem. The aim of this study was to optimize in vitro formation of collagen as a precondition for mechanical stability of new tissue. Human myofibroblasts were seeded on square sheets of biodegradable scaffolds (control). To stimulate collagen production, one series was cultured with L-ascorbic acid 2-phosphate. In a second series, the seeded scaffolds were subjected to tension by mounting them on a frame. After 4 weeks of culture time, the collagen content of the different series was assessed by hydroxyproline assay. Light and scanning electron microscopy were performed. Hydroxyproline content of the framed scaffolds was 10 times higher than that of the control group (p < 0.05) and 6 times higher than in the unframed scaffolds grown with ascorbic acid (p < 0.05), respectively. Scanning electron microscopy proved extensive formation of solid tissue in the framed samples. These results demonstrate that supplementation of myofibroblast cultures with ascorbic acid, especially if grown on strained scaffolds, significantly increases collagen content, which is crucial for mechanical stability. This concept is a further step toward the creation of a hemodynamically competent autologous heart valve.

Ascorbic Acid↗