Biomedical subjects
Publications and source records attributed to B A Reitz.
We describe a new type of mitral annuloplasty ring designed for use in the massively dilated mitral annulus. The ring can be fabricated at the operating table from a 4-mm Gore-Tex graft and umbilical tape and can be adapted in size to fit a mitral annulus of any diameter.
To determine the influence of valve selection on valve-related morbidity and mortality and patient survival, comparative long-term performance characteristics of mechanical (N = 68) and bioprosthetic (N = 73) heart valves were analyzed for 141 patients more than 70 years old who underwent isolated aortic valve replacement between 1970 and 1985. Cumulative patient follow-up was 491 patient-years (average, 4.3 years per patient). Hospital mortality was 18% and 19% for patients with mechanical valves and bioprosthetic valves, respectively. Survival at 5 years was 61 +/- 7% (+/- the standard error) and 67 +/- 10% for recipients of mechanical valves and bioprosthetic valves, respectively. Male sex (p = 0.014) and urgency of operation (p = 0.006) were independent risk factors for hospital mortality. Atrial fibrillation increased valve-related mortality (p = 0.01). No patient required reoperation or experienced structural valve failure. While anticoagulant-related hemorrhage was increased in recipients of mechanical valves (9.2 +/- 2.1%/patient-year) compared with recipients of bioprosthetic valves (2.3 +/- 1.1%/patient-year), it did not result in a death or lead to permanent disability. There was no difference in freedom from any valve-related complication at 5 years. However, when all morbid events are considered, recipients of bioprosthetic valves experienced fewer valve-related complications than patients receiving mechanical valves (10.7 +/- 2.3%/patient-year versus 17.6 +/- 2.5%/patient-year, respectively; p less than 0.05). The reduced incidence of anticoagulant-related hemorrhage and the infrequent need for warfarin sodium anticoagulation favor selection of a bioprosthetic heart valve in patients older than 70 years.
Cardiopulmonary bypass, hypothermia, temporary cardiac arrest and exsanguination represent the next logical step in the evolutionary management of intracaval neoplastic extension with renal cell carcinoma. This method of management provides control of the circulation of the entire body and allows for careful dissection in a bloodless field with less risk of embolization. From 1981 to 1986, 15 patients were treated with intracaval neoplastic extension of renal cell carcinoma above the level of the most inferior hepatic veins. In 6 patients mobilization of the vena cava with division of the hepatic veins to the caudate lobe allowed excision of the tumor and tumor thrombus without cardiopulmonary bypass (group 1). The remaining 9 patients underwent cardiopulmonary bypass and hypothermia (group 2). There was 1 postoperative mortality in the entire group. Most patients had advanced regional disease but the feasibility of this technique has been demonstrated. Survival appeared to be less in the bypass group. Although some of the patients have had metastatic disease, the quality of life and survival have been prolonged in many of these acutely ill patients.
Uncontrolled pulmonary hypertension during autoperfusion of the heart and lungs for preservation has been described, and it may result in extensive pulmonary injury and occasional early failure of the preparation. In order to investigate the neurohumoral mediators of the vasoconstrictor response in the pulmonary circulation of the autoperfused working heart-lung preparation, heart-lung organ blocks were harvested from calves, placed in a normothermic autoperfusion circuit, and studied. Effects of beta-adrenergic stimulation with isoproterenol, nonspecific vasodilatation with nitroglycerin, alpha-adrenergic blockade with phentolamine, phospholipase A2 inhibition with methylprednisolone, cyclooxygenase inhibition with indomethacin, and white blood cell depletion were independently evaluated. Untreated animals, pre- and postexplant, served as controls. Multipoint pulmonary vascular pressure-cardiac output plots were constructed for each animal. An index of pulmonary vascular resistance was obtained from the linear relation: mean pulmonary artery pressure minus pulmonary capillary wedge pressure divided by cardiac output. An intense flow-dependent pulmonary vasoconstrictor response was confirmed to exist in the denervated bovine autoperfused working heart-lung preparation. Isoproterenol afforded better protection against this response than the other agents studied. White blood cell depletion reduced postexplant pulmonary vasoconstriction, implying that circulating polymorphonuclear leukocytes mediate the response in the autoperfused working heart-lung preparation. White blood cell depletion and the administration of selected pharmacologic agents provide modalities for regulating the pulmonary vasoconstrictor response, and thus may enhance lung preservation in the autoperfusion model.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Eight beagles receiving heterotopic (cervical) cardiac allografts from outbred donors were evaluated by serial 31P NMR, septal endocardial biopsy, and left ventricular pressure measurements for signs of rejection. Early postoperative myocardial energy levels, as assessed by ratios of phosphocreatine to inorganic phosphate (PCr/Pi) and phosphocreatine to beta-ATP (PCr/B-ATP), were acceptable in all recipients. In these nonimmunosuppressed animals, the mean ratios of PCr/Pi and PCr/B-ATP progressively decreased, with a greater than 25% reduction noted by postoperative day two and greater than 50% reduction by day three. In sharp contrast, left ventricular end-diastolic pressures remained stable and at baseline levels for the first three postoperative days, and only then markedly increased. Likewise, histologic evidence of rejection did not become prominent until postoperative day four. These results suggest that metabolic abnormalities significantly precede either functional or histologic changes in rejecting allografts. The early detection of these metabolic changes by 31P NMR appears to have important potential for the noninvasive diagnosis of cardiac allograft rejection.
Currently there is no reliable technique for the diagnosis of lung allograft rejection. The presence of intraepithelial lymphocytes expressing the Leu-7 antigen is a specific marker of renal rejection. We examined whether immunoperoxidase techniques that detect Leu-7 positive lymphocytes could be used to diagnose lung rejection in heart-lung transplant recipients. In lungs from two autopsied patients with lung allograft rejection, numerous Leu-7 positive lymphocytes were present in the donor bronchial mucosa (32 and 65 cells/section), submucosa (23 and 80 cells/section), and submucosal glands (7 and 19 cells/section). These Leu-7 positive lymphocytes were associated with proximal airway injury, including squamous metaplasia, destruction of submucosal glands, and ulceration. In one case, there was bronchiectasis. Both cases also had distal airway bronchiolitis obliterans. In contrast, Leu-7 positive lymphocytes were not identified in the epithelium of the native trachea of these two patients; nor were they found in the bronchial epithelium of two sets of transplanted lungs without evidence of rejection. Only rare Leu-7 positive lymphocytes were evident in the epithelium (0 to 2 cells/section) and submucosal glands (0 to 1 cell/section) of 20 lungs from autopsied patients who had not received a transplant. Application of this technique to epithelial biopsy specimens obtained at bronchoscopic examinations demonstrated that it could be applied to the diagnosis of rejection in living heart-lung transplant recipients.
Explore the source record for details and available documents.
The significance of dynamic changes in energy state during lung harvesting and preservation has not been extensively studied. Phosphorus 31 nuclear magnetic resonance spectra at 81 MHz were obtained from degassed rabbit lungs. Changes in the adenosine 5'-triphosphate-to-inorganic phosphate peak-intensity ratios were used to measure changes in energy state. Two groups of rabbit preparations were studied to evaluate the effect of hypothermia during the initial 120 minutes of harvesting (n = 8 at 36 degrees C and n = 5 at 4 degrees C). The significance of these changes was assessed in a second experiment in which lungs were reperfused in vitro at selected intervals of hypothermia (5, 12, and 24 hours) and assessed for injury. Hypothermic preservation sustained a significantly higher energy state. The depletion of energy state was correlated with injury, particularly as measured by lung edema (r2 = -0.715). Short periods of warm ischemia (30 minutes) result in a significant depletion of energy state, which may be a component of pulmonary injury during harvesting and preservation.
Factors associated with increased operative mortality in patients with postinfarction angina have not been defined. Two hundred twenty-five patients underwent urgent coronary artery bypass grafting from 1982 through 1986. One hundred sixty-two men and 63 women averaged 62 years of age (range, 35-87 years). Operative mortality was 5.3%. To assess the predictors of perioperative mortality, 16 variables were evaluated by univariate and multivariate analyses. Significant independent predictors of perioperative mortality were the presence of a transmural anterior myocardial infarction (p less than 0.0005) and the need for preoperative intra-aortic balloon pumping for angina or congestive heart failure (p = 0.009). All perioperative mortalities (12 patients) occurred in this subset (anterior myocardial infarction, intra-aortic balloon pumping, or both) that included 101 patients. The mean follow-up period was 27.8 months (range, 1-69 months). There were 11 late deaths, resulting in an actuarial survival of 92 +/- 2%, 91 +/- 2%, 88 +/- 2.6%, and 88 +/- 4% at 1,2,3, and 4 years, respectively. Ninety-six percent of survivors were assigned to New York Heart Association Class I or II for congestive heart failure, and 96% were assigned to Class I or II for angina. Urgent coronary artery bypass grafting can be performed in patients with unstable postinfarction angina with acceptable mortality, although a significant increase in risk exists for patients with preoperative transmural anterior myocardial infarction, intra-aortic balloon pumping, or both.
Pulmonary infections remain one of the major complications of lung transplantation. The bronchus-associated lymphoid tissue (BALT) forms a local immune system that normally protects the lung from infection. The effects of lung transplantation and lung allograft rejection on the BALT were examined using immunoperoxidase techniques. The BALT was evaluated by quantifying the number of immunoglobulin-bearing plasma cells in the lamina propria of sections of trachea and mainstem bronchus. Sections of donor mainstem bronchus from 2 patients with allograft rejection were compared with sections of native trachea from these same patients, and with sections of mainstem bronchus from 2 transplanted lungs without rejection and 20 controls. Lung allografts from the 2 patients with rejection had a marked depletion of submucosal IgA-bearing and IgG-bearing plasma cells. Two sets of transplanted lungs without evidence of rejection showed only a mild reduction of the BALT. The depletion of BALT associated with allograft rejection may contribute to the increased incidence of pulmonary infections seen in these patients.
The gonadotropins luteinizing hormone, follicle-stimulating hormone, and human chorionic gonadotropin are composed of two noncovalently linked subunits, alpha and beta. The alpha subunit, identical in all three hormones, is produced in excess over the unique beta subunits by pituitary and placenta, and is secreted as uncombined, or free subunit. Free alpha subunit from both tissues has a larger molecular weight than the dimer form. In bovine pituitary an extra O-linked oligosaccharide is added to free alpha subunit, and this modification has recently been detected at an analogous position (threonine 39) on human alpha subunit secreted by choriocarcinoma cells. To assess the contribution of N-linked and O-linked oligosaccharides to the heterogeneity of human free alpha subunit, we have compared free alpha with human chorionic gonadotropin alpha secreted by explants and cultured cytotrophoblasts of human first trimester placenta. We have also examined the free and combined forms of human alpha subunit expressed in transfected C-127 mouse mammary tumor cells. Processing of the alpha subunit in placental and C-127 cells was similar. Tryptic mapping of placental-derived and transfected alpha subunits indicated that O-glycosylation at threonine 39 was not a major modification. In the presence of the oligosaccharide processing inhibitor swainsonine the difference in size between the free and combined forms of alpha was eliminated in both placental and C-127 cells, indicating that the two forms of alpha differed in their N-linked oligosaccharides. Furthermore, the oligosaccharides of free alpha subunits from placental and transfected cells were resistant to endoglycosidase H, but the combined forms of alpha were partially sensitive to the enzyme. Thus, in human first trimester placenta and mouse C-127 cells, combination of alpha with human chorionic gonadotropin beta alters the processing of N-linked oligosaccharides on alpha subunit.
Explore the source record for details and available documents.
In order to evaluate the applicability of infrared imaging for the assessment of myocardial perfusion, 10 open-chested dogs were studied by a real-time infrared imaging system. The left anterior descending coronary artery was occluded for 90 min followed by 210 min of reperfusion. During the experiment, myocardial surface temperature was mapped by an infrared imaging system with a thermal resolution power of 0.1 degree C and correlated with regional myocardial blood flow measured using radiolabeled microspheres. Following the experiment, acute myocardial injury was evaluated using triphenyltetrazolium chloride staining. After 90 min of ischemia, there was a significant correlation between myocardial blood flow and myocardial surface temperature (R = 0.694, P less than 0.001). After reperfusion, temperature did not correlate with blood flow, but there was a significant correlation between temperature and ischemic myocardial injury (R = 0.551, P less than 0.05). Temperature changes during acute regional ischemia and reperfusion may be regulated by the changes in myocardial blood flow and myocardial metabolism. Temperature analysis using real-time infrared imaging may be a useful means for the evaluation of myocardial blood flow and myocardial injury during ischemia and reperfusion.
The promoter of the capsid-coding genes of the autonomous parvovirus minute virus of mice (MVM) is shown to drive high levels of expression of the heterologous bovine growth hormone (bGH) gene in a bovine papilloma virus (BPV)-based shuttle vector. The expression of bGH directed by the MVM p39 promoter was, on average, higher than that obtained from the widely used metallothionein promoter. These results indicate that the MVM-p39/BPV shuttle vector will be generally useful for the high-level expression of heterologous genes.
Long-term performance characteristics of the Björk-Shiley standard aortic valve were determined by analyzing the follow-up of 514 patients undergoing operation between 1971 and 1981. Cumulative follow-up was 2,601 patient-years (average, 5.3 +/- 3.8 years); 53% (238/452) of hospital survivors have been followed more than 5 years. Valve-related complications expressed as both actuarial event-free percents (+/- standard error at 10 years) and first-event linearized determinations (percent per patient-year) occurred at the following rates: thromboembolism, 82 +/- 3 and 2.3 +/- 0.3, respectively; anticoagulant-related hemorrhage, 60 +/- 4 and 5.6 +/- 0.5; prosthetic valve endocarditis, 94 +/- 2 and 0.8 +/- 0.2; valve thrombosis, 97 +/- 1 and 0.4 +/- 0.1; reoperation, 94 +/- 2 and 0.6 +/- 0.2; valve failure, 82 +/- 4 and 1.6 +/- 0.2; and composite valve-related morbidity and mortality, 46 +/- 4 and 8.8 +/- 0.2. Overall survival was 72 +/- 2% at 5 years and 55 +/- 3% at 10 years; valve-related complications accounted for 22% of the late deaths. Although no instance of structural valve failure could be identified, 25% of valve-related complications resulted from valve failure, of which 67% were fatal. By 10 years, 54% of patients had experienced at least one form of major valve-related complication, 16% of which proved fatal. The Björk-Shiley standard aortic valve has late valve-related complications similar to other existing mechanical prostheses that have been subjected to long-term analysis.
The clinical introduction of cyclosporine has resulted in increased enthusiasm for cardiac transplantation. Since July, 1983, 61 patients (50 male and 11 female) have undergone orthotopic cardiac transplantation for cardiomyopathy (48 patients), ischemic heart disease (11), or congenital heart disease (2). Mean age was 39 years (range, 1.5 to 57 years). Median hospital stay was 26 days (range, 4 to 60 days). Maintenance immunosuppression consisted primarily of prednisone and cyclosporine; it was modified in 9 patients because of a pre-existing clinical condition. The incidence of rejection was 0.44 episode/patient-month within 3 months of cardiac transplantation and 0.10 episode/patient-month subsequently. The incidence of infection was 0.05 episode/patient-month. Major side effects of cyclosporine included renal dysfunction (63%) and hypertension (61%). No recipient required dialysis for renal dysfunction. Ten patients died (rejection, 4; infection, 3; carcinoma, 1; lymphoma, 1; and pulmonary hemorrhage, 1); actuarial survival at 1 and 2 years was 84 +/- 6% and 76 +/- 8%, respectively. Patient follow-up (cumulative, 719 patient-months) revealed that 96% of recipients were rehabilitated and 50% had returned to work. With increasing understanding of cyclosporine immunosuppression, recipients can continue to look forward to an extended life with nearly complete rehabilitation.