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Biomedical subjects

W E Richenbacher

Publications and source records attributed to W E Richenbacher.

At least 19 recordsLinked to original sources
PubMed1998

Reversal of renal failure and paraplegia after thoracoabdominal aneurysm repair.

Repair of ruptured thoracoabdominal aortic aneurysms is complicated by high rates of perioperative paraplegia, renal insufficiency, and mortality. This report describes a patient with a ruptured thoracoabdominal aortic aneurysm in whom preoperative acute renal failure was reversed with hemodialysis, aortic replacement, and renal revascularization. Prompt cerebrospinal fluid drainage reversed delayed-onset postoperative paraplegia and led to immediate, complete neurologic recovery.

Acute Kidney Injury↗
PubMed1998

The clamshell incision provides adequate exposure for aortic valve replacement and coronary revascularization.

The standard median sternotomy provides ready access to all surfaces of the heart and the ascending aorta. When cosmetic considerations, associated medical conditions, such as an esophageal stoma, or tracheostomy preclude use of the median sternotomy, a bilateral transverse sternotomy will provide excellent exposure of the entire ascending aorta and the lateral and inferior walls of the heart.

Blood Vessel Prosthesis Implantation↗
PubMed1998

Clinical evaluation of a new in-line continuous blood gas monitor.

Two methodologies for obtaining accurate blood gas and electrolyte values during cardiopulmonary bypass (CPB) are traditional laboratory analyzers, which use an electrochemical technology, and continuous in-line monitoring systems, which use a fluorometric and/or spectrophotometric technology. The purpose of the present study was to evaluate the accuracy of a new continuous in-line monitor, the 3M CDI Blood Parameter Monitoring System 500, which provides continuous in-line measurements of pH, PCO2, PO2, potassium (K+), oxygen saturation, hematocrit, hemoglobin, and temperature, during partial or complete CPB. Study parameters included arterial pH, PCO2, PO2, and K+ values. Overall performance was analyzed by calculating the mean difference (expressed as the bias) between the CDI system 500 and the laboratory analyzer for each parameter. The accuracy of the arterial pH, PCO2, and K+ values provided by the CDI system 500 was then evaluated using target values established in the acceptable performance standards for laboratory analyzers from the Clinical Laboratory Improvement Act of 1988 (CLIA '88). The accuracy of the PO2 value provided by the CDI system 500 was evaluated using a target value of +/- 10% of the reference, or laboratory analyzer, value. A prospective multi-center trial was conducted following Institutional Review Board approval. A total of 75 cases was included in the analyses, with over 200 data points from 4 clinical locations. Results for pH, PCO2, and K+ were within the target values established by CLIA '88. pH bias was 0.00 +/- 0.02 pH units. PCO2 bias was -0.3 +/- 3.3 mm Hg. K+ bias was approximately +0.12 +/- 0.31 mmole/l. Results for PO2 were within 10% of the reference value. PO2 bias was 7.5 +/- 13.8 mm Hg. The results of this clinical trial show that the CDI System 500 continuous in-line monitoring system provides values that meet the accuracy standards for laboratory analyzers for arterial pH, PCO2, PO2, and K+.

Bias↗
PubMed1995

Cannula selection and cannulation techniques for nonpulsatile mechanical ventricular assistance.

The successful use of mechanical ventricular assistance is, in large part, dependent upon easy insertion of well designed inflow and outflow cannulas. This manuscript describes a family of cannulas specifically designed for use in a nonpulsatile ventricular assist device (VAD) circuit. Although a variety of commercially available cannulas can be employed in a nonpulsatile VAD circuit, the cannulas described in this manuscript possess a number of unique design features. The reinforced thin-walled design and end hole construction optimize fluid flow characteristics in both the inflow and outflow cannula. The extended length allows the cannulas to transverse the skin at a point far distant from the mediastinum, reducing the potential for ascending cannula site infection. The purpose of this manuscript is not to review all cannulas available for nonpulsatile VAD circuits, but rather to describe in detail a family of cannulas that are ideal VAD cannulas based on their design characteristics. In addition individual cardiac surgeons implant very few of these devices annually. Thus the advantages and disadvantages of common cannulation sites and a proven technique for cannula insertion will also be presented.

Aorta↗
PubMed1992

Mediastinitis in heart transplantation.

Between March 1985 and December 1991, mediastinitis developed in 12 of 420 cardiac transplantation patients (2.8%). The mortality rate in this group of patients was 8.3% (1/12). Actuarial survival (1 year, 75%; and 5 years, 65%) was not significantly different from that of the group without mediastinitis (1 year, 88%; and 5 years, 75%). A higher percentage of the patients in the group with mediastinitis were listed as UNOS status 1 (50% versus 35%) and had a history of previous sternotomies (58% versus 44%). The presentation of mediastinitis was typical. Computed tomographic scanning with or without aspiration was a valuable adjunct in the diagnosis of mediastinitis. Induction immunotherapy with minimal steroids in the perioperative period was used in all patients. This may contribute to the patients' ability to mount an appropriate and effective response to infection, permitting earlier diagnosis. The debridement irrigation technique used in 8 of 12 patients had a low success rate of 33%, whereas the debridement muscle flap technique used in 4 of 12 was 100% successful in eliminating infection.

Actuarial Analysis↗
PubMed1992

Cardiac retransplantation: a viable option? The Registry of the International Society for Heart and Lung Transplantation.

To evaluate cardiac retransplantation as an appropriate utilization of scarce donor organs we analyzed data from the registry of the International Society for Heart and Lung Transplantation (ISHLT) (n = 449) and the Utah Cardiac Transplant Program (n = 20). Actuarial survival among retransplants was lower than in patients who received only one transplant in both the ISHLT registry patients (1 year survival, 48% versus 78%; p = 0.001) and the Utah series (1 year survival, 74% versus 88%; p = 0.06). Uncontrolled rejection, short interval (< 6 months) between transplantations, and the need for mechanical circulatory support were identified as risk factors for retransplantation. The incidence of rejection and infection was similar in first and second transplant recipients. Second transplant recipients had a higher level of sensitization, a greater incidence of donor-specific positive crossmatches, and an increased early mortality. Repetition in the second donor of mismatched HLA antigens present in the first donor did not adversely affect survival. If patients who underwent retransplantation within 6 months of their initial transplantation, those receiving transplants for uncontrolled rejection, and those requiring mechanical assistance were eliminated from the study, the short-term and long-term survival after cardiac retransplantation does not differ from that in patients having a single transplant.

Actuarial Analysis↗
PubMed1992

Outcome of cardiac transplant recipients with a positive donor-specific crossmatch--preliminary results with plasmapheresis.

To assess the influence of a positive T or B cell IgG crossmatch on the development of rejection and mortality following cardiac transplantation, we reviewed all cardiac transplants performed in Utah between March 1985 and October 1990. Of the 328 cardiac allograft recipients, 11 (3.4%) had an IgG positive crossmatch. Actuarial survival at 24 months in the positive crossmatch group was 57.3% +/- 0.02 while that of the controls was 86.1% +/- 2.1 (P < 0.05). Allograft rejection occurred earlier in recipients with a positive crossmatch (10.0 +/- 5.8 days versus 34.0 +/- 2.3 days, P < 0.001). The first allograft rejection episode in patients with a positive crossmatch was characterized by immunoglobulin and complement deposition in small blood vessels and interstitial edema and endothelial cell activation in the absence of a lymphocytic infiltrate. Furthermore, the allograft rejection in the positive crossmatch group was accompanied by hemodynamic compromise in a large proportion of the patients (73%). In addition to augmentation of immunosuppression, plasma exchange therapy was performed within the first week following transplantation in 8 of the 11 positive crossmatch patients. Survival in the patients treated with plasma exchange (75%) appears to be better than in those not receiving plasma exchange (33%) within one week of transplantation. While immunosuppressive therapy aimed at the humoral arm of the immune system and plasma exchange therapy may improve survival in recipients with a positive donor-specific crossmatch, survival is worse in patients with a positive crossmatch than in patients with a negative crossmatch. Thus, it would appear prudent to prospectively crossmatch cardiac transplant candidates with a greater risk of developing a positive crossmatch, such as those potential recipients with an elevated level of panel-reactive antibodies.

B-Lymphocytes↗
PubMed1990

Results of aortic anastomoses made under tension using polydioxanone suture.

After early repair of congenital cardiovascular defects, such as coarctation of the aorta, late stenosis may become a problem. Use of absorbable sutures has been shown to be superior to use of nonabsorbable sutures in allowing growth of an anastomotic site along with the individual. Some concern has been raised, however, about the potential for aneurysm formation at the site of anastomosis when absorbable sutures are used. This study was undertaken to observe the effects of longitudinal tension on anastomoses made with absorbable polydioxanone suture in growing animals. Six piglets (aged 3 to 4 weeks) underwent a 1-cm resection of the infrarenal aorta and reanastomosis with polydioxanone suture. One animal died prematurely of respiratory illness. The 5 remaining animals were killed after 6 months. The excised aortas demonstrated no stenosis, no dilatation, and no burst-test failure to 250 mm Hg. Histological examination showed disrupted elastic laminae without thinning of aortic wall in all samples of aorta. We conclude that polydioxanone suture is a suitable suture material for vascular anastomoses made under tension where growth of the anastomotic site is expected.

Anastomosis, Surgical↗
PubMed1990

Esophageal atresia, distal tracheoesophageal fistula, and an air shunt that compromised mechanical ventilation.

Infants with esophageal atresia and a distal tracheoesophageal fistula are predisposed to respiratory failure on the basis of prematurity, respiratory distress syndrome, aspiration of saliva, and reflux of gastric contents into the tracheobronchial tree. Thoracotomy and primary repair may be delayed to allow time for complete evaluation of the infant and respiratory stabilization. Poorly compliant lungs and a large distal fistula can result in selective passage of ventilatory gases into the gastrointestinal tract with resultant hypercarbia. Fogarty balloon occlusion of the distal esophageal segment halts this air shunt and facilitates effective mechanical ventilation.

Catheterization↗
PubMed1990

Pericardium as a thoracic aortic patch: glutaraldehyde-fixed and fresh autologous pericardium.

The repair of complex coarctation of the aorta often requires an aortic patch. Prosthetic patches lack growth potential and are associated with an increased incidence of aneurysm formation opposite the patch. We compared buffered glutaraldehyde-fixed patches, used in six animals (group 1), and untreated autologous pericardial aortic patches, used in five animals (group 2). Weanling pigs underwent pericardial patch replacement of a 1 X 2-cm diamond-shaped segment of the lateral wall of the descending thoracic aorta at the level of the aortic isthmus. Six months following patch aortoplasty, the animals were killed and the in situ patch dimensions were measured and compared to the measurements obtained at implantation. The increases in length, recorded as mean percentage change +/- SEM, were 34.7 +/- 3.7% for group 1 and 102.8 +/- 20.3% for group 2 animals; the increases in width were 91.4 +/- 31.7% for group 1 and 192.4 +/- 31.4% for group 2. The percentage changes for both length and width were significantly different between groups (P less than 0.05). Pull strength testing of standard-size patch samples demonstrated no significant difference in tensile breaking load between groups: group 1 = 959 +/- 277 g, group 2 = 795 +/- 86 g. Thoracic aortography revealed no evidence of stenosis or aneurysmal dilation in either group. Autologous pericardium is resilient, strong, and readily available and has expansile potential that makes it an ideal aortic patch material. We conclude that glutaraldehyde fixation does not provide additional strength and limits graft expansile potential when compared to untreated pericardium.

Animals↗
PubMed1989

Current status of cardiac surgery: a 40 year review.

Cardiac surgery has undergone dramatic advancements during the past 3 decades. The introduction of cardiopulmonary bypass and cardioplegic arrest ushered in the true era of open heart surgery. Bioprostheses and mechanical valves as well as techniques for valve reconstruction permit routine repair or replacement of stenotic and regurgitant native valves. Progress in the disciplines of mechanical and electrical engineering has led to the development of pocket watch-sized, physiologically responsive pacemakers as well as a variety of circulatory assist devices that include the intraaortic balloon pump, ventricular assist device and total artificial heart. The synthesis of cardiotonic and vasoactive drugs and advancements in anesthetic management, postoperative monitoring and nursing care greatly facilitate perioperative patient management. This summary of state of the art cardiac surgery begins with a brief historical background followed by a review of recent advances in six main categories: coronary artery disease, acquired valvular heart disease, congenital cardiac disease, cardiac transplantation, myocardial preservation and mechanical circulatory assistance. In conducting the review of recent literature, particular attention was directed to large clinical series that document the results of contemporary surgical procedures, novel therapeutic approaches to current clinical problems and unresolved controversies in the field of cardiac surgery. The abundance of surgical literature and constraints on the length of this article do not permit an exhaustive review. Apologies are extended to clinicians and laboratory investigators whose important contributions to the understanding and treatment of cardiac disease are not included herein.

Coronary Disease↗
PubMed1986

Mechanical support of the circulation followed by cardiac transplantation.

Improvements in both mechanical circulatory support devices and immune therapy promise a wider use of sequential mechanical support as a bridge to orthotopic cardiac transplantation. The intra-aortic balloon pump, the left and right ventricular assist pumps, and the pneumatic artificial heart represent the range of devices capable of keeping a patient alive who is awaiting a donor organ. The major difficulty in using circulatory support devices is infection, which is caused by their required percutaneous tubes. We report here our experiences with mechanical circulatory support devices as a bridge to cardiac transplantation. In a series of 31 consecutive transplant procedures, six patients have required preoperative mechanical circulatory support. The intra-aortic balloon pump was used in two patients for 2 and 14 days, respectively, before transplantation. Both patients are well 10 and 11 months after the transplant procedure. Two patients required the left ventricular assist device for 11 and 21 days and are alive 3 weeks and 8 months, respectively, after transplantation. One patient was supported by the pneumatic artificial heart for 10 days before a donor heart became available but died of septic shock 17 days after transplantation. A second patient received a pneumatic artificial heart 7 days after transplantation when the heart transplant failed. He has been in stable condition for 45 days but is recovering from renal failure. Our early experiences indicate that either partial or total mechanical support as a bridge to transplantation is successful if overwhelming sepsis or renal failure can be avoided.

Adult↗
PubMed1979

Thrombogenic potential of dacron grafts after prior exposure to whole blood, plasma, or albumin.

On hundred forty six (146) vascular graft insertions have been examined to determine the best exposure media, the mode of exposure, and the time of exposure required to change the TP of knitted dacron fabric. Whole blood, plasma, albumin, and Ringer's lactate (as control) were the media used. The mode of exposure was by either simple soaking or physiological perfusion with the appropriate media. The time of exposure was from one hour to 7 days. Simple soaking in species-specific albumin was found to be highly effective in lowering the TP of knitted dacron and we advocate this as the initial step in preclotting dacron grafts. This step is equally critical in the smaller vascular replacements and should lead to improved patency of these dacron vascular grafts.

Animals↗