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Biomedical subjects

A Haverich

Publications and source records attributed to A Haverich.

At least 199 records · Page 11Linked to original sources
PubMed1998

[Marfan syndrome: therapy of cardiovascular manifestations].

With optimal clinical management of patients with Marfan syndrome, life expectancy may be improved substantially from 32 years to a nearly normal life span. Cornerstones of clinical management comprise genetic counseling, life-style management, and cardiovascular surveillance, which includes regular aortic imaging and endocarditis prophylaxis. Prophylactic use of beta-blocking agents as well as timing of elective surgery and the choice of the optimal surgical technique are difficult issues that obviously need to be individualized. Juvenile or postoperative patients as well as pregnant patients with Marfan syndrome pose particular problems. This review intends both to facilitate differential decision making based on referenced evidence and to provide guidelines for therapeutic strategies. Finally, a review of the most recent advances to somatic gene therapy is given.

Adolescent↗
PubMed1998

[Aortic valve replacement as an independent predictive factor for later development of aortic dissection].

Dissection of the ascending aorta (type A) following later after aortic valve replacement has been described with increasing frequency. This study analyzes the role of aortic valve replacement for the evolution of late dissection. In a series of 80 consecutive patients with type A dissection, a previous aortic valve replacement had been performed in 12 cases (15%). In addition to arterial hypertension (p < 0.001) and Marfan syndrome (p < 0.01), multivariate analysis identified previous aortic valve replacement (p < 0.01) as an independent predisposing factor for type A dissection. Dissection occurred 3 +/- 4 years after aortic valve replacement with a clinical and anatomical profile similar to classic dissection as proven by comparison to a group of 62 patients with classic dissection associated with arterial hypertension or Marfan syndrome. With 75% and 66%, respectively, 30 day and 1 year survival of patients with dissection following later after aortic valve replacement was similar to patients with classic type A dissection. Extensive thinning and/or fragility (p < 0.05) of the aortic wall in the presence of a mildly dilated aorta (45 +/- 5 mm) at the time of aortic valve replacement was associated with a high risk for late dissection; this finding was substantiated by comparison to a control group of 10 consecutive patients with a similarly dilated aortic root but no dissection. Type and diameter of valve prostheses, cross-clamp time, NYHA functional class, and left ventricular ejection fraction were unrelated to late dissection. Previous aortic valve replacement is an independent predisposing factor for a dissection of the ascending aorta later. At the time of aortic valve replacement, prophylactic replacement or wrapping of the ascending aorta should be considered in patients with a thinned/fragile aortic wall even without a markedly dilated aortic root.

Adult↗
PubMed1998

Perspectives of operative myocardial revascularization--minimally invasive coronary bypass--an alternative?

Minimally invasive direct coronary artery bypass surgery has evolved as a reliable method to perform left internal mammary artery (LIMA) bypass surgery to the LAD. This novel technique represents a synthesis of known approaches to coronary surgery using sternotomy without extracorporeal circulation and limited access techniques in general thoracic surgery. Applying specially designed tools for both harvesting the internal mammary artery and mechanically stabilizing the anterior surface of the heart during anastomosis, this approach is gaining widespread acceptance. A steadily growing number of patients with proximal LAD lesions are submitted to cardiac surgery and the procedure is performed with increasing success rates, now approaching 98% short term patency. Improved cosmetic results, less surgical trauma, decreased length of stay in the hospital, and comparable longterm results to open LIMA bypass to LAD are the key characteristics of this new approach to single vessel coronary disease.

Adult↗
PubMed1998

Ultrastructural pathology of the alveolar type II pneumocytes of human donor lungs. Electron microscopy, stereology, and microanalysis.

Alveolar type II pneumocytes (PII) were studied in 12 human donor lungs perfused with modified Euro-Collins solution during single-lung transplantation (SLTx). While one lung was transplanted, the contralateral donor lung (cDL) was fixed at the time of SLTx for examination by electron microscopy, stereology, and microanalysis. Three groups were then formed: group A (n = 7), cDL without contusions, uneventful early postoperative course; group B (n = 3), cDL with conclusions, uneventful early postoperative course; group C (n = 2), cDL without contusions, early postoperative respiratory dysfunction. The major findings were that the presence of contusions had no effect on PII ultrastructure and that intracellular surfactant-storing lamellar bodies of cDL in group C were characterized by a higher volume-to-surface ratio (VsR) and larger area per cell profile than group A. Correlation analysis based on pooled data (groups A and C) showed that ischaemic time had little effect on PII ultrastructure and bore no relationship to postoperative clinical variables. The duration of preoperative donor intubation had a pronounced influence on ultrastructure and postoperative clinical variables. The stereologically estimated amount of intracellular surfactant and mitochondrial VsR were the only ultrastructural parameters that were significantly associated with early postoperative oxygenation. Lamellar bodies were the only ultrastructural components found to have a significant relationship to postoperative intubation time. The ultrastructural integrity of type II pneumocytes of human donor lungs is an important determinant of early respiratory function following clinical lung transplantation.

Adolescent↗
PubMed1998

Mechanism of luminal narrowing in cardiac allograft vasculopathy: inadequate vascular remodeling rather than intimal hyperplasia is the major predictor of coronary artery stenosis. Working Group on Cardiac Allograft Vasculopathy.

BACKGROUND: Despite increasing knowledge about degree and distribution pattern of intimal hyperplasia in cardiac allograft vasculopathy, coronary artery remodeling is only poorly understood in this disease. METHODS: To evaluate vascular geometry, intravascular ultrasound was used to characterize 57 advanced lesions in 35 consecutive transplant recipients. Lumen, plaque, and vessel area in these target lesions were compared with proximal and distal reference sites. RESULTS AND CONCLUSIONS: Vascular remodeling by compensatory local vessel enlargement (positive remodeling) and circumscript vascular constriction (negative remodeling) could be demonstrated. Plaque area in stenotic lesions was significantly increased compared with the mean reference site (5.6+/-3.0 mm2 versus 2.8+/-1.5 mm2, p < 0.001); however, inadequate compensatory enlargement rather than intimal hyperplasia was shown to be the most important predictor of luminal obstruction (r = 0.77, p < 0.001).

Blood Flow Velocity↗
PubMed1998

A new minimally invasive approach to the subclavian artery.

Aneurysms of the subclavian artery are rare. We report a case in which an aneurysm of the right subclavian artery presented as localized atrophy of the deltoid muscle. Operative repair was accomplished by a new minimally invasive surgical approach.

Adult↗
PubMed1998

Single-channel properties of L-type calcium channels from failing human ventricle.

OBJECTIVE: The aim of our study was to analyse the single-channel properties of L-type calcium channels from failing human heart and to compare them to the respective animal data. Furthermore, we intended to evaluate the feasibility of future single-channel studies on the role of calcium channels in the pathophysiology of heart failure. METHODS: Single L-type calcium channels were recorded in ventricular myocytes from explanted failing human heart, using the cell-attached configuration of the patch-clamp technique. RESULTS: One or more successful registrations of calcium channels could be obtained in 11 of 19 cell isolations. Determination of single-channel conductance yielded a mean value of 16.6 +/- 1.2 pS (70 mM Ba2+ as the charge carrier) under control conditions and 23.7 +/- 2.8 pS in presence of the calcium-channel agonist FPL 64176. The rapid gating process could be described by a C<-->C<-->O gating scheme. Slow gating analysis revealed a highly significant clustering of active and non-active sweeps. CONCLUSION: Single-channel measurements of L-type calcium channels in human failing ventricle are feasible and reproducible despite the varying patient characteristics. Their channel properties are qualitatively comparable to those found in other mammals. Whether there are quantitative differences due to the underlying heart failure can be elucidated in further studies.

Adult↗
PubMed1998

Cardiac valve endothelial cells: relevance in the long-term function of biologic valve prostheses.

OBJECTIVE: For reasons that are still unclear, biologic heart valve prostheses undergo degeneration after implantation. We studied the possible role of the immune system in this process. METHODS: We examined the expression of immunologically relevant molecules by human cardiac valve endothelium in situ and in vitro and studied re-endothelialization of implanted allogeneic and xenogeneic valvular surfaces using explanted bioprostheses and valves obtained from donor hearts at cardiac retransplantation. RESULTS: We demonstrate that human cardiac valve endothelial cells express molecules capable of initiating immune responses and might therefore play a role in the degeneration of viable cardiac valve prostheses. Also, we show evidence of re-endothelialization on the surfaces of xenografts and allografts but not on valves obtained from previously transplanted hearts. CONCLUSION: Inasmuch as valves from previously transplanted hearts seem to be free from degeneration, we conclude that reduction of the immunogenicity of allograft valve prostheses by HLA matching or immunosuppressive treatment might further improve long-term results after allograft valve replacement.

Antigens, CD↗
PubMed1998

Temporary distal occlusion for non-pharmacological preconditioning of harvested internal mammary artery grafts.

Perioperative spasm of the internal mammary artery (IMA) may result in early restriction of bypass flow. Therefore, pharmacological pretreatment is usually suggested. We present a technique of temporary distal occlusion of the transsected IMA using a metal clip. After 1 hour of storage in normal saline (SAL) there were significantly better flow rates compared with proximal application of a bull-dog clamp. No further increase in flow was noticed after submersion of the IMA pedicle in verapamil (VER). This technique easily provides sufficient IMA flow at the time of anastomosis, probably due to continuous endoluminal dilatation of the IMA by blood pressure, and thus avoids pharmacological pretreatment with vasodilators.

Aged↗
PubMed1998

Thoracic computed tomography prior to redo coronary surgery.

OBJECTIVE: Median resternotomy in coronary redo surgery represents a specific risk for injury of adjacent retrosternal structures. Aiming at improved preoperative evaluation of retrosternal structures, computed tomography (CT) techniques were routinely applied in redo cases. METHODS: Of 99 patients undergoing coronary reoperations since April 93, thoracic CT scans were retrospectively analyzed for retrosternal vicinity of cardiovascular structures, condition of the ascending aorta and structural abnormalities of the sternum. RESULTS: The minimal median distance between the posterior sternum surface and the anterior aortic wall was measured at 1.9 +/- 0.9 cm, whereas the mean closest distance to the anterior right ventricular wall was 0.4 +/- 0.5 cm. In 28 cases, the distance between sternum and aorta was smaller than or equal to 1 cm. No measurable distance between the sternum and the right ventricle was noted in 41 patients. Calcification of the ascending aorta became obvious 56 times. With respect to potential injury of the ascending aorta or the right ventricle, a safe reentry by resternotomy was facilitated in all cases. However, following complete sawing, the innominate vein became injured during retrosternal dissection in two cases. Preventive femoral vessel exposure was not performed and urgent femoral cannulation (n = 1) was infrequent. CONCLUSIONS: Thoracic CT scanning prior to redo coronary surgery allows for detailed assessment of retrosternal relations and facilitates reopening of the sternum. Preventive femoral vessel exposure and lateral thoracotomies may be avoidable in many cases.

Aortography↗
PubMed1998

Lung transplantation for cystic fibrosis--a single center experience over 8 years.

OBJECTIVE: Colonization of the lung and mediastinal lymph nodes with multi-resistant bacteria, diabetes and malnutrition represent potential risk factors for lung transplantation in cystic fibrosis. We therefore reviewed our experience in this patient population. METHODS: Between December 1988 and March 1997, 219 lung and heart-lung transplantations were performed at our institution. Of these, 39 procedures were done in 35 patients with cystic fibrosis. All candidates (mean age 26 years) were oxygen dependent (preoperative mean PO2: 44.8 +/- 9.1 Torr, preoperative mean PCO2: 53.4 +/- 10.5 Torr, one patient on respirator). Of the primary operations, 34 were performed as bilateral sequential lung transplants, one as a heart-lung transplantation. RESULTS: Mean duration on respirator for survivors was 3.1 (1-12) days, mean ICU and hospital stay were 4.7 (1-13) and 28 (12-79) days, respectively. The 3-month mortality rate was 5.7% (two patients died due to acute graft failure on days 36 and 73). Other causes of death in the follow-up were cerebral bleeding (one patient) and chronic graft failure (three patients). The survival rates were 91% at 1 year, 83% at 3 years and 76% at 5 years. In eight patients, a bronchiolitis obliterans syndrome (BOS) developed (in four cases grade 3). The freedom of BOS (grade 1 or more) at 1, 3 and 5 years was 87, 79 and 55%, respectively. Four retransplantations were performed. Of the 29 patients alive, only seven are physically limited. CONCLUSION: Bilateral lung transplantation for cystic fibrosis allows for acceptable early- and long-term results. Postoperative survival is not impaired by infection, diabetes and malnutrition. Long-term functional outcome seems to be comparable to lung transplantation in patients without infectious pulmonary disease.

Adult↗
PubMed1998

Tissue engineering of heart valves--human endothelial cell seeding of detergent acellularized porcine valves.

OBJECTIVE: Tissue engineering of heart valves represents a new experimental concept to improve current modes of therapy in valvular heart disease. Drawbacks of glutaraldehyde fixed tissue valves or mechanical valves include the short durability or the need for life-long anticoagulation, respectively. Both have in common the inability to grow, which makes valvular heart disease especially problematic in children. The aim of this study was to develop a new methodology for a tissue engineered heart valve combining human cells and a xenogenic acellularized matrix. METHODS: Porcine aortic valves were acellularized by deterging cell extraction using Triton without tanning. Endothelial cells were isolated in parallel from human saphenous veins and expanded in vitro. Specimens of the surface of the acellular matrix were seeded with endothelial cells. Analysis of acellularity was performed by light microscopy and scanning electron microscopy. Cell viability following seeding was assayed by fluorescence staining of viable cells. RESULTS: The acellularization procedure resulted in an almost complete removal of the original cells while the 3D matrix was loosened at interfibrillar zones. However the 3D arrangement of the matrix fibers was grossly maintained. The porcine matrix could be seeded with in vitro expanded human endothelial cells and was maintained in culture for up to 3 days to document the formation of confluent cultures. CONCLUSIONS: Porcine aortic valves can be almost completely acellularized by a non-tanning detergent extraction procedure. The xenogenic matrix was reseeded with human endothelial cells. This approach may eventually lead to the engineering of tissue heart valves repopulated with the patients own autologous cells.

Animals↗
PubMed1998

Inhaled nitric oxide and inhaled prostaglandin E1: effect on left ventricular contractility when used for treatment of experimental pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension (PHT) is a life-threatening complication after isolated heart and lung transplantation. Recent work has shown that inhaled nitric oxide (NO) in combination with inhaled prostaglandin E1 (PGE1) reduce pulmonary hypertension but their influence on cardiac contractility is less well defined. METHODS: This study investigated left ventricular contractility as measured by the 'Preload Recruitable Stroke Work-Relation' (PRSW) in 24 anesthetized open chest pigs, 12 receiving in random order NO (50 ppm), PGE1 (20 microg/ml) and their combination compared to 12 controls. PHT was induced by embolization with glass beads (500 microm). Prior to induction of PHT, sonomicrometric crystals were placed on the heart to measure instantaneous cardiac dimensions. Instantaneous intraventricular pressure (micro-tip catheter) and intraventricular dimensions were recorded digitally, while intraventricular volumes were calculated from the intraventricular dimensions applying the cylindric ellipsoidal volume model for the left ventricle. PRSW was calculated from the instantaneous pressure and volume data during rapid vena caval occlusion by analysis of generated pressure-volume loops. All data were analyzed by MANOVA and corrected for heart rate (level of significance #: P < 0.05); PRSW-slope measures contractility, (PRSW-X-intercept did not change significantly). RESULTS: PRSW-change +/- SEM (in percent of initial PRSW after induction of PHT) was -14.6% +/- 4.4% versus 1.6% +/- 4.4% for NO versus Control (P = 0.004), -8.8% +/- 4.6% versus 1% +/- 3.3% (P = 0.18) for PGE1 versus Control and -5.7% +/- 4.4% versus 2.5% +/- 4.2% for NO + PGE1 versus Control (P = 0.33), respectively. In summary, application of NO 50 ppm significantly reduced left ventricular contractility while PGE1 20 microg/ml and the combination of NO and PGE1 did not. CONCLUSION: If NO is not available, the sole application of nebulized PGE1 (20 microg/ml) appears to be safe with respect to left ventricular contractility in the setting of PHT. The combination of NO and PGE1 for the treatment of pulmonary hypertension should be considered for clinical application in situations where a combination of pulmonary hypertension and decreased left ventricular function is present.

Administration, Inhalation↗
PubMed1998

Effect of lung allograft ischaemia duration on postreperfusion graft function and postoperative course.

Lung transplantation is limited by the effects of ischaemia. Previous clinical studies related graft ischaemia duration to post-operative pulmonary function in the ICU, morbidity, and overall survival. This report describes the intraoperative pulmonary allograft function immediately after reperfusion. 23 lung transplantations (15 bilateral, 8 single) were analysed. Donor selection and organ procurement were identical. After pulmonary vasodilation with prostacyclin, allografts were flush-perfused with cold modified Euro-Collins solution. Mean duration of lung ischaemia was 255.1 +/- 35.1 min (190-314 min). Ischaemia times did not differ with respect to the recipient's disease or the use of extracorporeal circulation. After reperfusion, oxygenation indices deteriorated in 73.9% of patients compared with the native lungs (313.4 +/- 163.5 vs 427.2 +/- 96.1, p = 0.006). Linear regression analysis and subgroup analysis both revealed a significant influence of the duration of allograft ischaemia on early transplant function. Ischaemia of more than 4 hours resulted in an acceptable but significantly lower PaO2 (254.9 +/- 143.3 mmHg vs 463.0 +/- 149.2 mmHg, p = 0.011). However, mean time until extubation and time spent in the ICU were not affected. It is concluded that flush-perfusion of the lung with modified Euro-Collins solution provides reliable preservation of lung function up to four hours. Longer ischaemia, up to six hours, is followed by an acceptable but progressively reduced early transplant function.

Adult↗