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Biomedical subjects

B Reichart

Publications and source records attributed to B Reichart.

At least 289 records · Page 16Linked to original sources
PubMed1991

Surgery for the Wolff-Parkinson-White syndrome. The Groote Schuur Hospital experience.

Surgical division of accessory atrioventricular (AV) connections has been performed on 9 patients with the Wolff-Parkinson-White (WPW) syndrome at Groote Schuur Hospital. All patients had symptomatic paroxysmal tachycardia. The indication for surgery in 5 patients was poor control on antiarrhythmic drugs. Surgery was performed on a 15-year-old boy to prevent lifelong dependence on drugs, although his atrial fibrillation (ventricular rate greater than 300/min) was controllable with sotalol 1,280 mg daily. The remaining 3 patients required cardiac surgery for other indications and therefore their accessory pathways (APs) were divided concurrently. The AP was localised by pre-operative endocardial mapping and intra-operative epicardial mapping. There were 4 posteroseptal, 3 left free-wall and 2 right free-wall pathways. An endocardial approach was used to divide the pathways. All 5 free-wall APs were successfully divided without complications or recurrence. However, 1 patient with paroxysmal atrial fibrillation and severe unstable angina due to coronary artery disease died unexpectedly 10 days after 4-vessel coronary bypass grafting and division of a posteroseptal AP. Postoperative complications occurred in a further 2 patients with posteroseptal APs. One patient developed complete heart block and is now asymptomatic with a DDD pacemaker, while the other had recurrence of retrograde bypass conduction postoperatively, but is now successfully controlled on sotalol. Therefore 7 of the 8 survivors are free of recurrence of tachycardia on no anti-arrhythmic drugs after a mean follow-up of 14.3 months. New insights into the surgical technique, particularly for division of posteroseptal pathways, can be expected to improve the outlook.

Adolescent↗
PubMed1991

Pericardial mass mimicking constrictive pericarditis.

Persistent pericardial hematoma due to blunt chest trauma is extremely rare. We report a case of constricted myocardium resulting from a large, partially organized hematoma in the right cardiophrenic angle. The hematoma was assumed to be caused by an occupational accident 17 years before diagnosis. Constriction could only be controlled by complete removal of the fibrous posterior capsule of the hematoma, which covered the epicardium of the right heart.

Aged↗
PubMed1991

Effect of pH shifts induced by oxygenating crystalloid cardioplegic solutions.

Oxygenation of a bicarbonate-containing crystalloid cardioplegic solution alters the partial pressure of both oxygen (O2) and carbon dioxide (CO2). Therefore, oxygenating St. Thomas' Hospital II plus glucose (11 mmol/L) cardioplegic solution with 95% O2 + 5% CO2 induces a pH shift to 7.0 (10 degrees C) as opposed to pH 9.3 with 100% O2. In an isolated working rat heart model, we show that pH 7.0 (10 degrees C) improves mechanical postischemic recovery in the absence or presence of O2. However, in the absence of O2, pH 7.0 appears to inhibit glycolysis and diminish the stability of cellular membranes. The provision of O2 independently improved mechanical recovery and at pH 7.0, improved the preservation of the sarcolemma. Increasing the O2 content by including a perfluorocarbon (FC-43) in the oxygenated St. Thomas' plus glucose cardioplegia is not additionally beneficial. St. Thomas' Hospital plus glucose cardioplegic solution should be oxygenated, but with 95% O2 + 5% CO2 and not 100% O2.

Animals↗
PubMed1991

Adenosine cardioplegia: reducing reperfusion injury of the ischaemic myocardium?

Hyperkalaemia-induced hypopolarization of the sarcolemnal membrane during standard crystalloid cardioplegic arrest potentiates calcium influx during reperfusion and is associated with depletion of high-energy phosphate reserves. Adenosine has been shown to induce fast cardiac arrest whilst preserving membrane hyperpolarization in an isolated rat heart model. In this study we compared the efficacy of adenosine, both as an arresting agent and as an ultrastructural, haemodynamic and high-energy phosphate preserving agent, in an in situ global ischemia model in the baboon with St. Thomas' Hospital solution No. 2 (ST2; n = 8) and with Krebs-Henseleit buffer (KHB; n = 7). The addition of 10 mM adenosine to the non-cardioplegic KHB (ADO; n = 8) improved haemodynamic recovery significantly in terms of cardiac index (91.6% +/- 7.2 vs 59.9% +/- 9.9) and stroke volume index (101.6% +/- 8.9 vs 55.6 +/- 10.0) and was not statistically distinguishable from the ST2 with regard to cardiac index (91.6% +/- 7.2 vs 94.8% +/- 5.8), stroke volume index (101.6% +/- 8.9 vs 114.0% +/- 8.3) or left ventricular dP/dt (73.1% +/- 9.9 vs 87.0% +/- 12.4). Adenosine triphosphate was best preserved with ADO (103.5% +/- 21.1 vs 67.9% +/- 9.3 and 48.5% +/- 8.7) although this was not statistically significant. This suggests therefore that the mechanism of cardioprotection by adenosine occurs by means other than its role as high-energy phosphate precursor.

Adenosine↗
PubMed1991

Immunomodulatory therapy with thymopentin and indomethacin. Successful restoration of interleukin-2 synthesis in patients undergoing major surgery.

Prostaglandin E2 (PGE2)-mediated monocyte (M phi) suppressor activity and inadequate T-helper cell function represent the mechanistic keystones of trauma-induced impairment of cell-mediated immunity (CMI). In a prospective randomized trial, the immunorestorative potential of a combined therapy with the thymomimetic substance Thymopentin (TP-5; Timunox, Cilag GMBH, Sulzbach, FRG) and the cyclooxygenase inhibitor indomethacin (Indo) in 60 patients (mean age, 63 +/- 2 years) undergoing open heart surgery was studied. Perioperative immunologic screening was carried out on days -2, 3, 1, 5, and 7 and included the in vivo delayed type hypersensitivity (DTH) skin response, phenotyping for peripheral blood mononuclear cell (PBMC)-specific and nonspecific induction of lymphoproliferative responses, in vitro interleukin-2 (IL-2) synthesis, as well as the serum concentration of D-erythro-Neopterin (NPT) and of gamma interferon (gamma-IFN). The study protocol comprised three groups (n = 20): PA (Indo 150 mg administered intravenously on days 0 to 5), PB (TP-5 administered subcutaneously on days 0, 2, 4, and Indo), and PC (control). In contrast to PC, significant immunorestoration could be demonstrated in PB, as DTH scores on day 7, as well as proliferative responses in cell cultures were not depressed after operation (p less than 0.05). Cell-surface receptor expression for the CD3+, CD4+, and IL-2 receptor-positive (IL-2R+) lymphocyte subpopulations following surgery was reduced to 75% of baseline values in PC, while in PB, receptor protection for CD4+ and IL-2R+ subpopulations (more than 15% above baseline) was observed. Interleukin-2 synthesis (average baseline value, 0.7 + 0.08 U/mL) in cell cultures of PC was massively suppressed, with lymphokine concentrations in the supernatants never more than 0.27 +/- 0.05 U/mL. In PA cultures, IL-2 synthesis was impaired as well but not as precipitously as in PC. In contrast, in PB cultures, the average IL-2 production on consecutive postoperative days was never below baseline values. This study clearly demonstrates that the combined Indo/TP-5 therapy is superior to single Indo administration and can adequately preserve and/or restore intact M phi T-cell interaction and thus appears to be a feasible approach to maintain normal host defense activity in traumatized individuals.

Adjuvants, Immunologic↗
PubMed1991

St. Thomas' Hospital cardioplegic solution. Beneficial effect of glucose and multidose reinfusions of cardioplegic solution.

The intention of this study was to determine whether glucose is beneficial in a cardioplegic solution when the end products of metabolism produced during the ischemic period are intermittently removed. The experimental model used was the isolated working rat heart, with a 3-hour hypothermic 10 degrees C cardioplegic arrest period. Cardioplegic solutions tested were the St. Thomas' Hospital No. 2 and a modified Krebs-Henseleit cardioplegic solution. Glucose (11 mmol/L) was beneficial when multidose cardioplegia was administered every 30 minutes. Including glucose in Krebs-Henseleit cardioplegic solution improved postischemic recovery of aortic output from 57.0% +/- 1.8% to 65.8% +/- 2.2%; p less than 0.025. The addition of glucose to St. Thomas' Hospital No. 2 cardioplegic solution improved aortic output from 74.6% +/- 1.9% to 87.4% +/- 1.9%; p less than 0.005. Furthermore, a dose-response curve showed that a glucose concentration of 20 mmol/L gave no better recovery than 0 mmol/L, and glucose in St. Thomas Hospital No. 2 cardioplegic solution was beneficial only in the range of 7 to 11 mmol/L. In addition, we showed that multidose cardioplegia was beneficial independent of glucose. Multidose St. Thomas' Hospital No. 2 cardioplegia, as opposed to single-dose cardioplegia, improved aortic output recovery from 57.4% +/- 5.2% to 74.6% +/- 1.9%; p less than 0.025, and with St. Thomas' Hospital No. 2 cardioplegic solution plus glucose (11 mmol/L) aortic output recovery improved from 65.9% +/- 2.9% to 87.4% +/- 1.9%; p less than 0.005. Hence, at least in this screening model, the St. Thomas' Hospital cardioplegic solution should contain glucose in the range of 7 mmol/L to 11 mmol/L, provided multidose cardioplegia is given. We cautiously suggest extrapolation to the human heart, on the basis of supporting clinical arguments that appear general enough to apply to both rat and human metabolisms.

Animals↗
PubMed1991

Effect of oxygenation and consequent pH changes on the efficacy of St. Thomas' Hospital cardioplegic solution.

The hypothesis tested is that shifts in pH, induced when a cardioplegic solution is oxygenated, can be detrimental. We added either 100% nitrogen, 95% nitrogen and 5% carbon dioxide, 100% oxygen, or 95% oxygen and 5% carbon dioxide to the cardioplegic solution (St. Thomas' Hospital No. 2 plus glucose 11 mmol/L), and determined postischemic recovery of isolated rat hearts after 3 hours of 10 degrees C cardioplegic protected ischemia. Hearts were arrested and reinfused every 30 minutes throughout the ischemic period with cardioplegic solution. When 5% carbon dioxide was added to nitrogen, the pH of the cardioplegic solution decreased from 9.1 (100% nitrogen) to 7.0 (95% nitrogen: 5% carbon dioxide), a change associated with improved postischemic functional recovery. Aortic output improved from 52.3% +/- 2.7% to 63.9% +/- 2.8%, p less than 0.05, and cardiac output from 60.8% +/- 3.6% to 75.4% +/- 3.3%, p less than 0.01. This improvement was associated with diminished efflux of lactate during ischemia but increased postischemic release of lactate dehydrogenase. When nitrogen was replaced with oxygen, the addition of 5% carbon dioxide resulted in a similar decrease of pH, which again was associated with improved postischemic functional recovery. Aortic output improved from 66.3% +/- 2.8% (100% oxygen) to 88.9% +/- 3.7% (95% oxygen: 5% carbon dioxide), p less than 0.005, and cardiac output from 75.3% +/- 4.1% to 88.9% +/- 2.4%, p less than 0.01. The efflux of lactate during ischemia and the postischemic release of lactate dehydrogenase were similar in both groups. Furthermore, provision of additional oxygen with perfluorocarbons in an electrolyte solution identical to the St. Thomas' Hospital plus glucose solution and oxygenated with 95% oxygen: 5% carbon dioxide conferred no extra protection. In conclusion, the St. Thomas' Hospital No. 2 plus glucose cardioplegic solution should be oxygenated but with 95% oxygen: 5% carbon dioxide and not 100% oxygen because of the additive effect of a relatively "acidotic" pH.

Animals↗
PubMed1990

Surgical management of heart-lung transplantation.

Using cyclosporin A, long-term survival after heart-lung transplantation became possible. The drug blocks the immune system more selectively and leaves the tracheal wound healing unimpaired. Since 1981, 501 clinical cases have been collected by the registry of the International Society for Heart Transplantation. Candidates for heart-lung transplantation reveal signs of irreversible heart and lung diseases that may have been caused by cardiac lesions (valvular diseases, Eisenmenger reaction due to congenital malformations) or by pulmonic disorders (primary pulmonary hypertension, emphysema, fibrosis). The standard surgical procedure, which combines donor and recipient tracheas, right atria, and aortas, makes three anastomoses necessary. Immunosuppressive regimen includes cyclosporin A (blood trough levels of 300 to 500 ng/mL), azathioprine (1 to 2 mg/kg), and rabbit antithymocyte globulin (1 to 4 mg immunoglobulin G/kg). After the first two postoperative weeks, rabbit antithymocyte globulin is replaced by methylprednisolone (0.3 to 0.1 mg/kg; 500 mg are given intravenously after opening the aortic cross-clamp; 3 x 125 mg on postoperative day 1). After heart-lung transplantation an extreme variety of problems may evolve. Early postoperative complications (within the first postoperative month) comprise acute isolated lung rejection, multiorgan failure, and bacterial pneumonia. Diagnosis of acute lung rejection proves difficult; it includes clinical signs, chest radiographic appearances, and cytoimmunological monitoring. Transbronchial lung biopsies are of similar value for precise diagnosis as are endomyocardial specimens after heart transplantation. Late postoperative complications (after 1 postoperative month) comprise viral pneumonia, fungal infection, tuberculosis, and chronic obliterative bronchiolitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Heart-Lung Transplantation↗
PubMed1990

Endothelial cell toxicity of solid-organ preservation solutions.

Endothelial cell damage caused by myocardial cardioplegic solutions (Bretschneider HTK and St. Thomas' Hospital No. 2) or renal and hepatic cold storage solutions (modified Collins and University of Wisconsin solution) was assessed in monolayer cultures of adult human venous endothelial cells at 4 degrees to 10 degrees C with phase-contrast microscopy. St. Thomas' Hospital solution caused the cells to contract, resulting in disruption of monolayer integrity and opening of intercellular gaps, and resulted in a 24-hour postexposure survival of 51.0% +/- 2.4%. Bretschneider HTK solution altered cellular morphology less and produced the best postexposure survival (80.2% +/- 2.6%; p less than 0.001). Although morphology was altered the least with University of Wisconsin solution, postexposure survival with this solution, which was similar to that with modified Collins solution, was superior to that with St. Thomas' (p less than 0.01) but inferior to that with Bretschneider HTK (p less than 0.05). The superior protection provided by Bretschneider HTK was due to its additives histidine, tryptophan, and KH-2-oxygluterate (p less than 0.005), and to its low chloride content (p less than 0.005). Furthermore, modifying St. Thomas' solution by decreasing its chloride content improved cell survival to 71.2% +/- 2.3% (p less than 0.001). Normothermic (37 degrees C) exposure to Bretschneider HTK, modified Collins, and University of Wisconsin solution was cytotoxic, whereas normothermic exposure to St. Thomas' cardioplegia was not. In conclusion, the preservation solution that is the least harmful to endothelial cells at hypothermia is Bretschneider HTK cardioplegic solution.

Adenosine↗
PubMed1990

Non-invasive assessment of right and left ventricular volumes 11 to 24 years after corrective surgery on patients with tetralogy of Fallot.

Patients who had corrective surgery for tetralogy of Fallot using a transannular right ventricular outflow tract (TRVOT) patch showed a higher risk of post-operative mortality and reoperation in the long-term follow-up. A total of 642 patients were operated upon for tetralogy of Fallot between 1952 and 1982. Twenty-six patients who survived for more than 10 years were selected for this study. Fifteen randomly selected patients (group 1) without outflow tract patch were compared with 11 patients (group 2) where a transannular right ventricular outflow patch had been used. Right and left ventricular volumes were assessed using combined first-pass and equilibrium radionuclide ventriculography. After administration of 25 mCi of 99mTc-pertechnetate, data were acquired with a gamma camera with a large viewing field and the patient at rest and during exercise. The patients in group 1 were able to manage a workload of 65 +/- 24 W on the bicycle ergometer while the patients in group 2 could only reach a mean maximum of 34 +/- 12 W. Right ventricular end-diastolic volume (RV-EDV) at rest was 198 +/- 67 ml in group 1 and 224 +/- 69 ml in group 2. During exercise, RV-EDV was increased to 218 +/- 75 ml in group 1 (P less than 0.01) and to 246 +/- 79 ml in group 2. Right ventricular end-systolic volumes did not change significantly during exercise. In group 1, the left ventricular (LV) volumes were comparable to the normal; in group 2, LV-EDV was diminished at rest and during the stress test.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Heart-lung transplantation in 1990--indications, surgical technique, postoperative complications and outcome.

Using cyclosporine A (CyA), long-term results after heart-lung transplantation became possible. Since 1981, 761 clinical heart lung transplantations have been registered at the International Society for Heart Transplantation. Candidates for this operation reveal signs of irreversible heart and lung diseases which are caused by cardiac lesions (e.g. valvular disease, Eisenmenger reaction due to congenital malformation) or pulmonary disorders (e.g. primary pulmonary hypertension, emphysema, fibrosis). The standard surgical procedure necessitates three anastomoses which combine donor and recipient tracheae, right atria and aortae. Immunosuppression consists of CyA (blood levels of 300-500 ng/ml), azathioprine (1-2 mg/kg/d) and rabbit antithymocyte globuline (RATG) (IgG: 2-4 mg/kg/d). After the first 2 postoperative weeks, RATG is replaced by low dose methylprednisolone (0.3-0.1 mg/kg/d). As an alternative, RATG may be omitted completely. Postoperatively, a variety of complications may evolve. Early problems (within the first month) comprise acute pulmonary rejection, bacterial pneumoniae, and multiorgan failure. Diagnosis of acute lung rejection proves difficult; it includes clinical signs, chest radiographic appearances and cytoimmunological monitoring of the peripheral blood. Transbronchial lung biopsies are for precise diagnosis of similar value to endomyocardial biopsies after heart transplantation. Late postoperative complications comprise viral, bacterial, fungal, and protozoal infections and chronic obliterative bronchiolitis. With increasing experience, the 30 day mortality fell to below 20% according to the International Society for Heart Transplantation. The one-year survival rate between 1986 und 1988 was reported to be 61%. The results of some individual groups are even better.

Bronchiolitis Obliterans↗
PubMed1990

15-Deoxyspergualin for induction of graft nonreactivity after cardiac and renal allotransplantation in primates.

In order to assess the immunosuppressive potentials of 15-deoxyspergualin (15-DS) in a preclinical experiment, heterotopic cardiac (n = 27, group I) and classic renal (n = 25, group II) allotransplantations were performed in Chacma baboons. The following immunosuppressive regimens were applied: Groups IB and IIB were treated with 15-DS alone (4 mg/kg/day) for p.o. days 0-9. Groups IC and IIC were treated with cyclosporine A (10-40 mg/kg/day) for p.o. days 0-30. Groups ID and IID received a combination of 15-DS (for p.o. days 0-9) and CsA (for p.o. days 0-30). Groups IA and IIA served as control and received no medication. The mean graft survival was 11.0 days for group IA, 28.2 days for group IB (P less than 0.05; IB vs. IA), 32.4 days for group IC, and 43.1 days for group ID (P less than 0.025; ID vs. IA). After renal transplantation, the corresponding figures were 12.3 days for group IIA, 8.5 days for group IIB, 30.4 days for group IIC and 148.9 days for group IID (P less than 0.025; IID vs. IIA). After cardiac and renal transplantation, acute rejection was the main cause of graft failure. Treatment-related side effects, mainly gastrointestinal complications, were observed only in primates, who were treated with 15-DS alone. After cardiac transplantation, permanent graft non-reactivity was not achieved, but a delayed rejection occurred within a mean of 21.8 days after immunosuppression had been stopped. Following renal transplantation, graft nonreactivity was also not achieved in groups IIB and IIC. In group IID, however, 4 of 8 animals (50%) were graft-tolerant 340, 256, 244, and 164 days after treatment discontinuation. Thus, the combination of 15-DS and CsA led to a significant prolongation of graft survival in both groups. Long-term nonreactivity was achieved only after renal transplantation, when initially treated with 15-DS and CsA.

Animals↗