Publications by authors named "Sievers H"

Purpose: Microdialysis allows the biochemical analysis of interstitial fluids of nearly every organ as a bedside procedure. This technique could be useful to reveal data about the myocardial metabolism during cardiopulmonary bypass in human coronary artery bypass graft (CABG) surgery.

Methods: In 17 patients undergoing CABG a myocardial microdialysis catheter (CMA 70, CMA/Microdialysis AB, Sweden) was inserted in the apical region of the beating heart.

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Background And Aim Of The Study: Rejection is thought to contribute to the degeneration of valved homografts. A novel cryopreserved decellularized homograft valve (SynerGraft; CryoLife, Inc.) offers the unique opportunity to gain new insight into the immunology of homograft implantation and its significance for valve function.

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Endoaneurysmorrhaphy is mostly performed on anterior-septal left ventricular (LV) aneurysms. It may also be applied to posterior aneurysms, which is technically more challenging. Whether the surgical risk is the same, irrespective of the location of the aneurysm, has not been studied before.

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Objective: Numerous investigations could not clarify the exact mechanism of transmyocardial laser revascularization (TMLR). The aim of this study was to investigate, whether TMLR leads to an increase of myocardial oxygenation in comparison to patients undergoing coronary artery bypass grafting (CABG).

Design: Twelve patients (TMLR group) underwent TMLR alone with an 800 W CO2 laser through a left anterior thoracotomy.

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The short left main trunk with early bifurcation is a common variation of the left coronary anatomy and is easily overlooked during antegrade selective cardioplegia resulting in the risk of single branch perfusion. We describe an obvious characteristic sign to detect this pitfall during blood cardioplegia.

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Background: Venous coronary artery bypass grafts (CABGs) are prone to accelerated atherosclerosis. In atherosclerotic diseases, serum C-reactive protein (CRP) levels have become an important diagnostic and prognostic marker. The origin of CRP in this setting remains to be elucidated.

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Background: Since the early 1990s, the pulmonary autograft is predominantly implanted as a freestanding root for less aortic valve regurgitation is reported. However, there is a certain risk of dilatation of the root over time potentially impairing valve function. We favor since 8 years the original subcoronary or inclusion technique to preserve the root of the patient as a restrain to dilatation.

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Background And Objective: The Ross procedure (pulmonary autograft) has since the 1980s attracted growing interest as an alternative to the widely practised insertion of a prosthetic aortic valve. The 12-year experience of a consecutive series from one centre are reported here.

Patients And Methods: Between February 1990 and January 2002 a Ross procedure, predominantly with the subcoronary technique, was performed in 244 consecutive patients with aortic valve disease (244 men, 54 women, mean age 46 +/- 13.

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Objective: The value of prophylactic brachytherapy on vein graft disease is unknown.

Methods And Results: Vein bypass grafts in 23 hypercholesterolemic pigs after ex vivo gamma irradiation of the vein grafts (10, 20, and 40Gy) and 16 control veins were analyzed regarding: (1) expression of platelet-derived growth factor (PDGF-AA and -BB, ELISA); (2) smooth muscle cell (SMC) proliferation/cell death (double-immunohistochemistry Mib-1/TUNEL/SMC alpha-actin); and (3) vessel wall dimensions. Planimetric data on vessel wall dimensions revealed no positive effect of gamma radiation on neointima formation and inner lumen diameter.

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Background: Aortic valve-sparing operations for acute type A dissection are appealing and innovative but less well defined surgical techniques requiring further evaluation.

Methods: We reviewed all consecutive patients with acute type A dissection who underwent either the remodeling (group 1, n = 21) or the reimplantation valve-sparing technique (group 2, n = 15) since October 1994. Patients were followed up clinically and echocardiographically for as long as 41.

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Aims/hypothesis: The aim of this study was to assess whether cardiac catecholamine release is affected in patients with Type 2 diabetes mellitus.

Methods: A trial tissue was obtained from 19 diabetic (Type 2) and 43 non-diabetic patients undergoing coronary surgery. Endogenous norepinephrine release was examined under baseline conditions as well as during electrical field stimulation (effective voltage 5 V, stimulation frequency 4 Hz, pulse width 2 msec) by high performance liquid chromatography and electrochemical detection.

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Background: Atrial fibrillation (AF) is the most frequent complication after cardiac surgery and can cause considerable morbidity. Low-energy cardioversion (LEC) using biatrial epicardial wires implanted during surgery has been shown to be effective and safe in conscious patients, but has not been directly compared with medical treatment so far. We therefore prospectively studied the efficacy of LEC in men 60 years of age and older.

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Background And Aims Of The Study: Bicuspid aortic valve (BAV) is a common inherited condition that is often accompanied by ascending aortic aneurysm. A high level of histological wall abnormalities was reported to be present in non-dilated aortas of patients with BAV. In patients with tricuspid aortic valve, there appears to exist a direct relationship between the diameter of the ascending aorta and degree of histopathological aortic wall abnormalities.

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Optimal function of the aortic root relies upon the ability of its component structures to move in a coordinated fashion. Some of the cells that make up the structures of the aortic root have been shown to contain nerves, receptors, and contractile elements. The ability to contract or relax may contribute to the successful function of the valve by allowing it to move in a coordinated manner in response to biological stimuli.

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Introduction: Cryopreserved homograft valve conduits have been used to reconstruct the right and left ventricular outflow tract. Long-term studies have shown homograft degeneration and calcification, and it has been postulated that immunological mediated phenomena in a manner similar to that seen in chronic rejection may contribute to the degeneration process. The development of a decellularized, non-glutaraldehyde-fixed valve conduit creates a non-immunogenic connective tissue matrix for autologous recellularization by host cells.

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Background: Cardiopulmonary bypass induces a generalized inflammatory reaction accompanied by free radical generation. Depletion of antioxidants could result and is reported for vitamin E and C. We investigated the effect of cardiopulmonary bypass on plasma concentrations of alpha-tocopherol, retinol, and biochemical variables (e.

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Background: In the Fontan circulation power supply for maintaining adequate lung perfusion via a total cavopulmonary connection is limited. This study, aiming at the detection of energy consuming variables, compares the influence of two different pulmonary arteriotomy shapes on power losses across cavopulmonary connections.

Methods: Two types of surgical junctions of cavopulmonary connections were studied in a mock circulation.

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This case report shows that atelectasis of the left lung-induced by extrinsic compression of the left main bronchus by an aortic aneurysm and persisting despite aggressive conservative treatment-may be effectively treated by bronchial stenting and high-frequency percussive ventilation.

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Background: The present pilot study was conducted to evaluate the effect of isolated short-term lung perfusion during cardiopulmonary bypass (CPB) on inflammatory response and oxygenation.

Methods: A total of 24 patients undergoing elective cardiac surgery with routine CPB were prospectively assigned to three groups. Group I (n = 7), control subjects receiving neither lung perfusion nor ultrafiltration; group II (n = 9), patients undergoing lung perfusion; and group III (n = 8), patients undergoing lung perfusion plus ultrafiltration.

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Background: At first glance the aortic valve is a relative simple valve mechanism connecting the left ventricle and the ascending aorta. Detailed analysis of the different components of the aortic valve including the leaflets and sinuses revealed a complex motion of each part leading to a perfect durable valve mechanism at rest and during exercise. Theoretically, the reconstruction or imitation of these structures in patients with aortic valve disease should lead to optimal results.

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Background: During cardiopulmonary bypass, the activated clotting time is frequently used for determination of anticoagulation, and either Celite or kaolin are used as activators. If aprotinin is administered concomitantly, the Celite activated clotting time (C-ACT) becomes significantly higher than the kaolin activated clotting time (K-ACT). Therefore, insufficient anticoagulation using C-ACT in the presence of aprotinin is a major concern.

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Optimally designed cavopulmonary connections are desirable to reduce transanastomotic power loss. Since aplanarity of the total cavopulmonary connections results from the natural anterior-posterior position of the superior vena cava and the right pulmonary artery, the aim of this study was to investigate the influence of aplanarity of caval offset on transanastomotic power losses. Two types of cavopulmonary connections, a planar cross-like connection and a nonplanar V-shaped anastomosis, were studied in a mock circulation, comparing for each type native porcine vessels and Perspex glass models.

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The case is reported of a 42-year-old patient who underwent a Ross procedure for aortic valve insufficiency due to endocarditis in 1991, using the free-standing root technique. Autograft valve function was stable for up to 10 years postoperatively, though dilation of the autograft root occurred. With an increasing size of the root diameter (50 mm), however, progressive aortic regurgitation developed which necessitated reoperation.

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