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W Konertz

Publications and source records attributed to W Konertz.

At least 19 recordsLinked to original sources
PubMed2006

Is there a possibility for a glutaraldehyde-free porcine heart valve to grow?

OBJECTIVE: A challenging issue is to create a heart valve with growth and remodeling potential, which would be of great interest for congenital heart valve surgery. This study was performed to evaluate the growth and remodeling potentials of a decellularized heart valve. METHODS: In 4 juvenile sheep (age 12 +/- 1 weeks) with a weight of 24.3 +/- 4.4 kg, a 17-mm diameter decellularized porcine valve was implanted as pulmonary valve replacement. Valve growth was evaluated by transthoracic echocardiography. At explantation, valves were evaluated by gross examination, light microscopy (hematoxylin and eosin, von Kossa, Sirius red, Weigert and Gomori staining), electron microscopy and immunohistochemistry. Atomic absorption spectrometry was performed to evaluate calcium content. RESULTS: All animals showed fast recovery. The mean follow-up was 9.0 +/- 1.8 months. All sheep at least doubled their weight (54.3 +/- 9.2 kg). Echocardiography showed no regurgitation and a flow velocity of 0.7 +/- 0.1 m/s at the latest follow-up. The valve diameter increased from 17.6 +/- 0.5 to 27.5 +/- 2.1 mm (p < 0.018). Gross examination showed a similar wall thickness of the implanted valve and native pulmonary wall, with smooth and pliable leaflets. Histology showed a monolayer of endothelial cells, fibroblast ingrowth and production of new collagen. No calcification was seen at von Kossa staining, confirmed by low calcium content levels of the valve wall and leaflets at atomic absorption spectrometry. CONCLUSIONS: This glutaraldehyde-free heart valve showed not only the absence of calcification, but also remodeling and growth potential.

Animals↗
PubMed2006

Clinical experience with the 3F stentless aortic bioprosthesis: one-year follow up.

BACKGROUND AND AIM OF THE STUDY: The 3F equine aortic bioprosthesis is a new stentless valve which is currently undergoing evaluation in a multicenter clinical trial and is considered to have superior hemodynamic performance. Herein is reported the authors' initial experience with the 3F valve, focusing on the hemodynamic performance of the device. METHODS: Between March 2002 and October 2003, 35 patients (age range 61-86 years) underwent aortic valve replacement with the 3F valve implanted in the subcoronary position. Evaluation of valve hemodynamic performance was assessed at discharge (postoperative day 5 +/- 2), at 3-6 months, and at 11-14 months' follow up by means of transthoracic echocardiography. The mean preoperative transvalvular pressure gradient was 63 +/- 14 mmHg. Before surgery, all patients were in NYHA class III or IV, despite aggressive medical treatment. Five patients underwent concomitant coronary artery bypass grafting. RESULTS: The implanted valve sizes ranged from 21 to 29 mm. There were no operative deaths and no major perioperative complications. After 12 months, mean pressure gradients for the 23-, 25-, 27- and 29-mm valves were 13, 13, 12 and 9 mmHg, respectively. Mean systolic pressure gradients and NYHA class were improved significantly after surgery. Mild signs of hemolysis and minimal central regurgitation were detected in some patients, but were of no clinical importance. Valve dysfunction or mechanical failure did not occur during the follow up period. CONCLUSION: Because of its flexible structure, the 3F aortic bioprosthesis is simple to implant, and no major adverse effects have been associated with such valve implantation at the authors' center. Transprosthetic gradients appeared to regress at 6-12 months' follow up. The durability of the device is yet to be established in ongoing long-term trials.

Aged↗
PubMed2005

Impact of implantation technique on hemodynamic results of the Pericarbon Freedom stentless valve.

BACKGROUND: The Pericarbon Freedom stentless valve has shown excellent hemodynamic results in the midterm course. However, there is no information as to whether a continuous or interrupted suture technique at the inflow site has an impact on postoperative hemodynamics. METHODS: 139 patients were enrolled in a non-randomized, prospective matched trial. An interrupted suture line technique was used in 68 patients and a continuous suture line technique was used in 71 at the inflow site. Isolated valve replacement was performed in 70.4% of the continuous and 67.6% of the interrupted suture group. Pre- and postoperative hemodynamics and one-year follow-up were obtained by echocardiography and expressed as mean and peak gradients and grade of regurgitation. RESULTS: No significant difference between continuous and interrupted suture techniques were noted with respect to mean (11.8 +/- 6.3 vs. 12.5 +/- 6.2 mm Hg, p = 0.251) and peak gradients (21.0 +/- 9.6 vs. 22.0 +/- 10.9 mm Hg, p = 0.292) as well as to the degree of regurgitation. Bypass and cross-clamping times decreased by 22.4 and 20.6 minutes, respectively, with the use of the continuous suture technique. One year follow-up showed a further, significant decrease of mean and peak gradients. CONCLUSIONS: The Pericarbon Freedom stentless valve appears to offer excellent postoperative performance. The suture line technique at the inflow site does not result in any hemodynamic differences.

Aged↗
PubMed2005

Results of a decellularized porcine heart valve implanted into the juvenile sheep model.

OBJECTIVE: This study was performed to evaluate the possibility of creating a glutaraldehyde-free porcine xenograft to improve long-term durability. METHODS: A decellularized porcine pulmonary valve was implanted into the right ventricular outflow tract of 7 juvenile sheep. Valves were explanted after 3 months (n = 4) and 6 months (n = 3). Evaluation was performed by gross examination, radiography, histology (hematoxylin-eosin and Sirius red staining), and immunohistochemistry. Quantitative determination of calcium content was investigated by atomic absorption spectrometry. RESULTS: All animals showed fast recovery without complications. At explantation, all decellularized valves showed smooth and pliable leaflets without evidence of thrombosis. The valve wall was also smooth and pliable without hardness. Light microscopy showed a monolayer of host endothelial cells covering the inner surface of the heart valves and repopulation of host fibroblasts into the deeper layers. Sirius red staining enabled visualization of the production of new collagen. Radiographic results showed an absence of calcification, confirmed by the low calcium levels (1.08 +/- 0.28 microg/g and 0.73 +/- 0.31 microg/g at 3 and 6 months, respectively) revealed by atomic absorption spectrometry. CONCLUSIONS: The results with the juvenile sheep model showed that decellularized heart valves are recellularized in vivo. Host endothelial cells form a monolayer on the inner surface of the valve matrix. Furthermore, host fibroblasts repopulate the valve matrix and produce collagen; thus, a remodeling potential can be expected.

Animals↗
PubMed2004

Splanchnic oxygen transport, hepatic function and gastrointestinal barrier after normothermic cardiopulmonary bypass.

BACKGROUND: The effect of non-pulsatile, normothermic cardiopulmonary-bypass (CPB) on the splanchnic blood-flow and oxygen-transport, the hepatic function and the gastrointestinal barrier were observed in a prospective observational study in 31 adults undergoing cardiac valve replacement surgery. METHODS: The splanchnic (i.e. hepatic) blood-flow (HBF) was measured by the constant infusion of indocyanine-green (ICG) using a hepatic-venous catheter. Liver function was examined by calculation of lactate uptake, ICG extraction and the monoethylglycinexylidide (MEGX) test. A day before and after surgery the gastrioduodenal and intestinal permeability was measured by determination of sucrose and lactulose/mannitol excretion. RESULTS: Splanchnic blood flow and oxygen delivery did not decrease during and after surgery while splanchnic oxygen consumption (P < 0.0125) and arterial lactate concentrations increased. The splanchnic lactate uptake paralleled the lactate concentration. After but not during CPB an increase of systemic oxygen consumption was observed. The MEGX test values decreased on the first day after surgery. The ICG extraction was attenuated during the operation. The gastroduodenal and the intestinal permeability increased significantly postoperatively (P < 0.002, respectively, P < 0.001). There was no correlation between these findings and the duration of CPB. There was a significant correlation of the intestinal permeability but not of the gastroduodenal permeability between the prior and after surgery values (P < 0.001). CONCLUSION: Increased oxygen consumption during CPB may indicate an inflammatory reaction due to the pump beginning in the splanchnic area or a redistribution of the splanchinc blood flow during the CPB. Normothermic CPB does not lead to a significant or prolonged reduction of liver function. Normothermic CPB causes an increase of gastrointestinal permeability. The intestinal barrier function prior to surgery was accountable for the degree of loss of intestinal barrier function following surgery.

Adult↗
PubMed2003

Effects of different steroid treatment on reperfusion-associated production of reactive oxygen species and arrhythmias during coronary surgery.

BACKGROUND: During conventional cardiac surgery ischemia and reperfusion may cause excessive production of reactive oxygen species leading to tissue damage including early arrhythmias. We therefore assessed the kinetics of markers of radical stress including oxidized and reduced glutathione (GSSG/GSH), oxidized proteins (PCG) and malondialdehyde (MDA), and tested the hypothesis that different steroid treatments inhibit these markers and early reperfusion-associated supraventricular and ventricular extrasystolic beats. METHODS: In a randomized, controlled, blinded, prospective trial 36 patients received a preoperative infusion of methylprednisolone (MP, 15 mg kg-1, n = 12), tirilazad mesylate (TM, 10 mg kg-1, n = 12) or placebo (PL, NaCl, n = 12). Coronary sinus and arterial blood was drawn at baseline and 2, 5, 15, 30, 60 and 240 min after aortic declamping. Holter-ECG analysis was used to identify arrhythmias. RESULTS: Cardiac GSSG release occurred very early (< 15 min) and was not significantly attenuated by either drug treatment. Cardiac PCG production showed biphasic increases, lasted > 4 h and was significantly reduced only by TM. Cardiac MDA release was short (< 30 min) and significantly reduced by MP and TM. Neither treatment had a significant influence on the early occurrence of ventricular or supraventricular arrhythmias. The number of patients needing cardioversions or defibrillations also were not different. CONCLUSIONS: The results indicate that cardiac production of reactive oxygen species occurs after reperfusion in humans and is not inhibited by steroid treatment. Steroid treatment effectively reduces lipid peroxidation during cardiac surgery but has no influence on arrhythmias.

Aged↗
PubMed2003

Effect of piracetam on cognitive performance in patients undergoing bypass surgery.

In this study, the protective effect of piracetam on select aspects of cognitive function in patients undergoing bypass surgery was investigated. Male patients (n = 64) with an indication for a surgical revascularization using artificial extracorporal circuits were randomly assigned in a double-blind fashion to receive a single challenge of 12-g piracetam infusion or placebo (sterile saline) prior to the bypass surgery. A brief battery of neuropsychological tests for verbal and non-verbal short-term memory and attention was administered 1 day before and 3 days after the surgical intervention. There was a significant difference in short-term memory and attention, with the piracetam-treated patients producing a better level of performance 3 days after surgery compared to the placebo group. The overall postoperative cognitive function (z-transformation of all 6 test results) was more significantly (p < 0.001) reduced in the placebo group than in the piracetam group (z = -1.19 +/- 0.72 vs. -0.46 +/- 0.58, respectively). A single challenge of 12-g piracetam infusion prior to surgical intervention might offer a short-term neuroprotective effect for patients undergoing cardiac bypass surgery. Whether this effect persists for a longer period of time requires further investigation.

Adult↗
PubMed2003

Quality management system of a university cardiac surgery department according to DIN EN ISO 9001 : 2000.

BACKGROUND: A quality management system (QMS) will improve quality in health care units. This report describes the introduction of a QMS according to ISO 9001:2000 in a university cardiovascular surgery department. METHODS: First, a thorough analysis of all processes of patient treatment and clinical research was obtained. Multiple interfaces were defined to different departments as well as to administration units. We evaluated and optimized all necessary resources, evaluating customer satisfaction using patients' and referring physicians' surveys. We started quality rounds including surgeons, nurses and technicians. Based on this preparation, we redefined and explained all processes including their responsibilities and necessary resources in the quality manual. RESULTS: After a process of 18 months, an independent, accredited organization recommended that our QMS be given certification according to ISO 9001:2000. CONCLUSIONS: Certification of a university cardiovascular surgery department according to ISO 9001:2000 is possible, and may represent the first step towards total quality management (TQM). In complex health care units, certification of separate departments may help generate a consciousness of quality on the way to TQM.

Accreditation↗
PubMed2003

[Evaluation of passive cardiomyoplasty using left- and right-ventricular volume measurements by EBCT and MRI in patients with chronic congestive heart failure].

PURPOSE: To evaluate the efficacy of passive cardiomyoplasty with the determination of biventricular volumes, global systolic function as well as left-ventricular muscle mass. MATERIALS AND METHODS: In 19 patients with congestive heart failure of idiopathic or ischemic origin, a polyester mesh-graft was implanted around both ventricles for stabilization and functional support. Before and three months after surgery, 15 patients underwent EBCT and 4 patients with impaired renal function underwent MRI, for the evaluation of the volume and ejection fraction of both ventricles. RESULTS: EBCT demonstrated a decrease from 385 to 310 ml in LV-EDV, from 312 to 242 ml in LV-ESV, from 209 to 160 ml in RV-EDV and from 149 to 87 ml in RV-ESV, and an increase from 20 to 26% in LV-EF and from 37 to 50% in RV-EF as well as a reduction of LV-MM from 300 to 274 g (p < 0.05 each). Similar results were obtained by MRI. CONCLUSION: Following passive cardiomyoplasty, EBCT and MRI revealed an improvement of the global systolic function as well as a reduction of biventricular volumes and left-ventricular muscle mass.

Adult↗
PubMed2003

Visualization of the pulmonary valve using cine MR imaging.

PURPOSE: To evaluate the capability of bright-blood cine MR to directly visualize the leaflets of the valve replacement in pulmonary position following Ross operation. MATERIAL AND METHODS: Long and short axis views of the pulmonary valve were obtained in 10 normal subjects and 14 patients after Ross operation. Valve morphology and function were analyzed and signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were calculated. Flow measurements were performed in the pulmonary trunk to assess pulmonary regurgitation. RESULTS: In all subjects, tricuspid morphology of the pulmonary valve was visualized. SNR of the leaflets in normal subjects (9.8 +/- 3.0) and in patients after Ross operation (7.5 +/- 2.2) differed significantly from blood (12.6 +/- 3.2 and 11.3 +/- 2.5, respectively, p < 0.05). Valvular regurgitation was seen in 5 patients as an insufficient closure of the valve which was confirmed by flow measurements. CONCLUSION: Cine MR enables in-plane visualization of the pulmonary valve and allows for functional and morphological evaluation in patients after pulmonary valve surgery.

Adult↗
PubMed2003

Reoperation in a Jehovah's Witness 22 years after aortic allograft reconstruction of the right ventricular outflow tract.

We report the case of a 29-year-old male Jehovah's Witness who presented with hemolysis and right heart failure as a consequence of extreme calcification of an aortic valve-containing allograft and Dacron prosthesis that had been placed 22 years earlier to repair tetralogy of Fallot. Reoperation had been denied by several other centers, because of the patient's refusal to undergo blood transfusion. For 2 weeks preoperatively, we raised the patient's hemoglobin level by treating him with recombinant erythropoietin, oral iron, and folic acid. At surgery, under normothermic cardiopulmonary bypass, we replaced the aortic allograft in the right ventricular outflow tract with a cryopreserved pulmonary allograft, also containing a valve. The postoperative course was uneventful, and the patient was released from the hospital on the 13th postoperative day in excellent condition.

Adult↗
PubMed2002

Coronary artery bypass grafting supported with intracardiac microaxial pumps versus normothermic cardiopulmonary bypass: a prospective randomized trial.

OBJECTIVE: To analyze the difference in coronary artery bypass grafting (CABG) performed with normothermic cardiopulmonary bypass (CPB) and CABG supported with the intracardiac microaxial pump (ICP, Impella, Aachen, Germany). METHODS: A prospective randomized study was conducted in seven centers. The study population consists of 199 patients undergoing isolated primary CABG (CPB group 94 patients, ICP group 105 patients). Both groups are equal in demographic variables, number of bypasses performed, and Euroscore predicted mortality. We analyzed clinical outcome, myocardial enzymes and blood parameters of hemolysis, organ function and inflammatory response. RESULTS: Seventeen patients (16%), randomized in the ICP group, were switched to the CPB group. This was due to the inability to position the right side catheter adequately (n=8), to a pump failure (n=1) or to the perioperative decision that beating heart surgery is technically not possible (n=8). There was no significant difference between the two study arms regarding the pump assistance time (CPB 67.1+/-22.9 min; ICP 67.7+/-30.3 min; P=0.88861), the number of grafts (CPB 2.4+/-0.7; ICP 2.3+/-0.8) and the number of grafts to the back wall (CFX; both groups n=37). There is no significant difference in clinical outcome, evolution of myocardial enzymes, indices of organ function and hemolysis. There is a reduced inflammatory response in the ICP group as indicated in the postoperative release of granulocyte elastase (CPB 259+/-195; ICP 150+/-126 microg/l; P<0.00001) and complement C3 (CPB 0.73+/-0.2; ICP 0.65+/-0.2g/l; P=0.008). CONCLUSION: The intracardiac pump for the right heart is difficult to introduce. As a consequence the right side pump underwent design modifications. There were no differences in clinical outcome between both groups. The inflammatory response is significantly reduced in the ICP group.

Aged↗
PubMed2002

Influence of transmyocardial laser revascularization (TMLR) on regional cardiac function and metabolism in an isolated hemoperfused working pig heart.

The mechanism of an indirect revascularization in ischemic myocardium by transmyocardial laser revascularization (TMLR) is not yet fully understood. An improvement of clinical symptoms caused by TMLR is reported in many clinical trials with patients in which a direct revascularization is not possible. An increase of myocardial perfusion through laser channels is doubtful, because the myocardial pressure in the wall is higher than in the cavum. Therefore we measured the local cardiac function (intramyocardial pressure, wall thickness, pressure-length curves) and acute metabolic changes (tissue lactate content, tissue pO2) in ischemic and nonischemic regions before and after TMLR in isolated hemoperfused pig hearts. An isolated heart was chosen because it enabled us to separate coronary flow from flow through ventricular channels. The ischemia was induced by coronary occlusion or microembolization (eight hearts each). It should be noted that microembolization leads to conditions which are more comparable with those found in patients selected for TMLR. In the isolated working heart, the coronary perfusion can be controlled independently from perfusion through the ventricular cavum. Under the ischemic conditions mentioned above, we observed that the intramyocardial pressure in the ischemic region decreased below the left ventricular pressure, so one premise for indirect perfusion was met. TMLR after microembolization led to a significant improvement of regional cardiac work and the tissue oxygen pressure. These acute effects demonstrate the possibility of functional and metabolic amelioration by TMLR after ischemia induced by microembolization in an isolated hemoperfused pig heart.

Analysis of Variance↗
PubMed2002

In vitro hydrodynamics of a decellularized pulmonary porcine valve, compared with a glutaraldehyde and polyurethane heart valve.

BACKGROUND: Hydrodynamic performance of a decellularized pulmonary porcine valve was evaluated with a computer versatile pulse duplicator and compared to glutaraldehyde fixated stentless porcine bioprosthesis and a polyurethane heart valve. METHODS: Decellularized pulmonary porcine matrices (Group I, n = 5) were treated chemically to become cell-free collagen matrices. The findings of this heart valve were compared with aortic glutaraldehyde treated porcine prostheses (Group II, n = 5) and polyurethane three leaflet valve prostheses (Group III, n = 1). Measurements were performed in 0.9% saline test fluid at room temperature. Measurements compared were closing time, closing volume, systemic pressure difference and energy losses. Each valve was measured 6 times with 70 beats/minute, a stroke volume of 70 ml corresponds to a cardiac output of 4.9 L/minute. RESULTS: Group I and group III showed no significant differences between parameters. The measured closing time was significantly different (p < 0.001) between group I and II, respectively 24.333 and 53.600 ms and group II and III respectively 53.600 and 24.000. Difference in closing volume was significant (p < 0.05) between groups II and I respectively 3.67 and 0.68 ms and group II and III respectively 3.67 and 0.71. Systolic mean pressure gradient was 18.25 +/- 1.04 mm Hg in group II which was significantly different (p < 0.001) from groups I and III, respectively 10.65 +/- 0.29 mm Hg and 7.70 +/- 0.30 mm Hg. CONCLUSIONS: Decellularized pulmonary porcine valves showed the same excellent performance as polyurethane valve prosthesis, which are superior to the investigated glutaraldehyde fixed xenograft.

Animals↗
PubMed2001

Risk factors for prolonged ventilation after cardiac surgery using APACHE II, SAPS II, and TISS: comparison of three different models.

OBJECTIVE: To identify the risk for prolonged mechanical ventilation in cardiac surgical patients. DESIGN: Prospective study with retrospective combination of a second database. PATIENTS: Six hundred and eighty-seven patients after cardiac surgery over a period of 12 months. MEASUREMENTS: Demographic data were recorded preoperatively, and surgical procedures intraoperatively using a surgical database designed for quality control. Length of ICU and hospital stay, and hospital outcome were recorded. Severity of illness was assessed daily using APACHE II, SAPS II, and Organ Failure Score. Intensity of treatment and nursing care was monitored by means of the Therapeutic Intervention Scoring System (TISS). Univariate and multivariate analyses were performed using logistic regression. The predictive value of the identified variables was tested by the Wilcoxon test using the receiver operating characteristic curve. MAIN RESULTS: Sixty-two patients (9.0%) were ventilated for > 48 h and accounted for 42.8% of the total costs in the ICU. The pre- and intraoperatively collected data produced a model with weak predictive capacity for prolonged ventilation [area under curve (AUC) 73.22 and 71.08, respectively]. The use of TISS and SAPS postoperatively resulted in an effective model of prediction (AUC 93.76). Adding the occurrence of reoperation, reintubation, emergency transfusion, intraaortic balloon pumping, and need for total parenteral nutrition to the model further improved its predictive capacity (AUC 94.74). CONCLUSIONS: The present results strongly suggest that data collected postoperatively using established scoring systems as well as documented events of high clinical impact for risk assessment and quality control are reliable predictors of prolonged ventilation.

APACHE↗
PubMed2001

[Indications, technique and initial results of passive cardiomyoplasty].

The cardiac support device (CSD, Acorn Cardiovasc. Inc.), a knitted polyester tissue, is surgically placed over the ventricles to prevent further dilatation of the heart. The aim of this study was to evaluate the feasibility and safety of CSD implantation in patients with advanced heart failure from cardiomyopathy of either idiopathic or ischemic origin. From April 1999, 23 patients received the CSD. In 8 patients the CSD implantation was the only surgical measure; in 12 patients a concomitant mitral valve repair was performed. In three more patients, the CSD implantation was combined with other surgical procedures. The CSD was placed while on bypass with the heart beating, attached to the AV groove and tailored anteriorly to snugly fit the ventricles. There were no intraoperative deaths or complications. Two patients died early postoperatively (4 d, 21 d); 1 late death occurred (44 d postop). The deaths were not considered to be device related. There were no CSD-related adverse events. Six months postoperatively all patients improved by at least one NYHA class. Echocardiography at 6 months revealed an increase in LVEF; the LVEDD decreased accordingly. Mitral valve regurgitation improved in all patients. These findings indicate that the CSD is safe, and improves heart failure symptoms and left ventricular function. Additional studies have to confirm these results.

Adult↗