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Biomedical subjects

N Bleese

Publications and source records attributed to N Bleese.

At least 19 recordsLinked to original sources
PubMed2001

Mosaic valve international clinical trial: early performance results.

BACKGROUND: A new third generation porcine bioprosthesis was developed in an attempt to improve on hemodynamic performance and durability of current prostheses. METHODS: One thousand, two hundred, sixty patients underwent aortic valve replacement and 366 patients underwent mitral valve replacement between February 1994 and September 2000. The cumulative follow-up was 3,696.3 patient-years for aortic valve replacement and 880.1 patient-years for mitral valve replacement. Follow-up was complete for 95.5% of aortic valve replacement patients and 97.5% of mitral valve replacement patients. RESULTS: For aortic valve replacement, freedom from valve-related adverse events at 1 year was 96.5%+/-0.5% for antithromboembolic-related hemorrhage and 100% for structural valve deterioration. Freedom from valve-related adverse events at 5 years was 93.8%+/-2.6% for antithromboembolic-related hemorrhage and 99.3%+/-0.9% for structural valve deterioration. For mitral valve replacement, freedom from valve-related adverse events at 1 year was 96.0%+/-1.1% for antithromboembolic-related hemorrhage and 100% for structural valve deterioration. Freedom from valve-related adverse events at 4 years was 92.1%+/-3.7% for antithromboembolic-related hemorrhage and 100% for structural valve deterioration. CONCLUSIONS: These results support the claim that the Mosaic bioprosthetic valve is efficacious and safe, but continued follow-up is mandatory to determine mid- and long-term performance.

Adult↗
PubMed2001

Correction of congenital heart defects and mitral valve operations using limited anterolateral thoracotomy.

PURPOSE: Median sternotomy, which generally is used as a standard access for atrial septal defect (ASD) and mitral valve operations, has a significant risk of postoperative instability/osteomyelitis of the sternum. Moreover, especially in young women, the resulting large scar is a poor cosmetic result that may have adverse psychological consequences. Our presentation suggests that these difficulties may be avoided by the use of a less invasive approach consisting of a limited anterolateral thoracotomy with standard cannulation. MATERIAL AND METHODS: From June 1997 until December 1999, 13 women, mean age 31.9 +/- 9.2 years, with atrial septum defect (n = 8), sinus venosus defect with partial anomalous pulmonary venous connection (n = 1), left atrial myxoma (n =1) or mitral valve regurgitation (n = 3), were scheduled for less invasive operation. In all cases a double lumen tube was used for ventilation. After a submammarian skin incision of about 10 cm a limited anterolateral thoracotomy was performed in the fifth right intercostal space. For cannulation of the ascending aorta a trochar cannula was used. Both caval veins were cannulated by angled vena cava catheters. Standard cardiopulmonary bypass was established using normothermia in all patients undergoing operations with correction of congenital heart defects and mild hypothermia (32 degrees C) in the three patients undergoing mitral valve operation. Surgery was performed in cardioplegic arrest using Bretschneider's solution. All corrections of congenital heart defects were performed by Goretex patches. Mitral valve reconstruction was carried out in two patients, and one patient underwent mitral valve replacement. RESULTS: No complications occurred in any of the 13 patients peri- or postoperatively. Total time of operation was 211.9 +/- 36.0 minutes, the perfusion time was 77.0 +/- 25.8 minutes, and the aortic cross-clamp time was 51.8 +/- 21.9 minutes. Mean stay in ICU was 1.2 +/- 0.4 days (total hospital stay: 7.8 +/- 2.2 days). Postoperative thoracic x-ray and cardiac echocardiography/dopplersonography revealed no pathological findings in any patients. CONCLUSION: Atrial septal defect operations, including partial anomalous pulmonary venous connection, left atrial myxoma and mitral valve operations, can be performed safely and effectively using a limited anterolateral thoracotomy and standard cannulation technique with excellent cosmetic results.

Adolescent↗
PubMed2000

Clinical outcome of patients with and without renal impairment undergoing a minimally invasive LIMA-to-LAD bypass operation.

PURPOSE: Patients with renal impairment undergoing conventional coronary artery bypass grafting (CABG) have a significant risk of postoperative deterioration of kidney function. We investigated the outcome of patients with and without renal impairment treated by off-pump coronary artery surgery. METHODS: From January 1997 until January 2000, 158 consecutive patients (mean age 63 +/- 9.8 years, 126 male, 32 female) underwent minimally LIMA-to-LAD bypass operations. The patients were divided into three groups: group I patients (n = 133) had a preoperative creatinine of < 1.3 mg/dL, group II patients (n = 21) had a creatinine of > 1.3 mg/dL, and patients of group III (n = 4) required chronic dialysis due to terminal kidney dysfunction. Monitoring of the blood creatinine was performed during the entire hospital stay. A postoperative angiogram was performed in 113 of the 158 patients. RESULTS: All operations were performed without intraoperative complications. Postoperative angiograms revealed a patent LIMA-to-LAD bypass in all but one patient, who demonstrated a dissection of the left internal mammary artery (LIMA) graft. Mean creatinine value on admission was 1.0 +/- 0.1 mg/dL in group I and 2.7 +/- 1.9 mg/dL in group II. The maximal postoperative creatinine value was 1.1 +/- 0.4 mg/dL in group I and 2.9 +/- 2.7 mg/dL in group II. Neither hemofiltration nor hemodialysis was necessary in any patient of group I or group II during the postoperative course. CONCLUSION: Minimally invasive LIMA-to-LAD bypass is a safe and effective procedure with low morbidity and no mortality in the first 158 patients. Preoperative renal impairment had no adverse effect on outcome or residual kidney function. Thus, higher doses of diuretics and hemofiltration/dialysis were not used, resulting in a cost reduction. Therefore, this approach may be worthwhile to consider in patients with significant renal impairment who have to undergo CABG.

Aged↗
PubMed1999

A new method for coronary occlusion and local stabilization during minimally invasive LIMA-to-LAD-bypass.

The minimally invasive direct coronary occlusion and stabilizing technique (midCOAST)-system, a new device for coronary occlusion and local stabilization during minimally invasive LIMA-to-LAD-bypass is presented. A closed platform with an oval opening in its center provides optimal immobilization together with platform-fixed vessel-loops, which are used for LAD-occlusion. Clinical results in 72 consecutive patients indicate that the midCOAST-device can be safely and effectively used for minimally invasive LIMA-to-LAD-procedure, even in patients with impaired left ventricular function. Due to the optimal immobilization of the target area the quality of the LIMA-to-LAD-anastomosis, documented by post-operative angiography (62/72), was excellent in all cases.

Adult↗
PubMed1998

Beating heart operations including hybrid revascularization: initial experiences.

BACKGROUND: The outcome of patients (n = 45) with coronary one- to three-vessel disease undergoing beating heart operations using a recently developed stabilizing device was investigated. METHODS: Left internal mammary artery-to-left anterior descending coronary artery (LIMA-to-LAD) revascularization was carried out alone (n = 31) or as hybrid procedure in combination with a balloon angioplasty (n = 14). RESULTS: All 45 patients underwent a successful LIMA-to-LAD procedure without intraoperative complication during a 21 +/- 8-minute (range, 10 to 53 minutes) LAD occlusion time. In 14 hybrid procedures a total of 19 stenoses including 3 left main stenoses were treated successfully by percutaneous transluminal coronary angioplasty and stenting. The postoperative courses were uneventful with the exception of two surgical reexplorations necessitated by bleeding. No worsening of renal, neurologic, or respiratory functions occurred in any patient. In the group having a single LIMA-to-LAD procedure, early postoperative coronary angiograms (22 of 31) showed a patent LIMA graft and excellent anastomosis; this was also true in 4 patients 12 months after operation as shown in angiograms. All patients undergoing hybrid revascularization demonstrated a patent LIMA-to-LAD anastomosis; in 1 patient there was a dissection in the midlevel of the LIMA, which was stented successfully. The 6-month follow-up angiograms in 7 of 14 patients revealed open LIMA bypass grafts in all patients except 1, who was stented because of dissection. CONCLUSIONS: These data indicate that a beating heart operation including hybrid revascularization is safe and effective in selected patients with coronary one- to three-vessel disease including left main stenosis. This approach may be especially advantageous in comparison with conventional coronary artery bypass grafting in patients with severe concomitant disease.

Adult↗
PubMed1997

Recombinant hirudin as an anticoagulant during cardiac operations: experiments in a pig model.

OBJECTIVE: The efficacy and safety of recombinant hirudin (r-hirudin) compared with heparin as an anticoagulant during open-heart surgery has been studied in a pig model. METHODS: A total of 18 Göttingen minipigs were randomly divided into three treatment groups and subjected to cardiopulmonary bypass for 1 h. Heparin-treated animals received a bolus of unfractionated heparin of 400 IU/kg body weight. Recombinant hirudin was given by a bolus injection of 1 mg/kg body weight, followed by a 1 h lasting infusion of 1 mg/kg body weight per h. The heparin-anticoagulated animals and one group of the hirudin-treated animals additionally received aprotinin at a dosage of 17500 KIU/kg body weight (KIU, kallikrein inhibitory units). In the second group of r-hirudin-treated animals, the aprotinin was replaced by saline. RESULTS: The extracorporeal circuit remained patent for a 1 h pump period in all of the animals studied. There was no evidence of vascular occlusion or clot formation in the r-hirudin-treated animals. The anticoagulant efficacy of the hirudin protocol used is further demonstrated by the results of electron-microscopical scans of the pump-line filters. Fibrin deposits were visible only in the heparin-treated animals and not in r-hirudin-treated pigs. Despite this strong anticoagulant effect, there was no evidence of an increased bleeding tendency in r-hirudin-treated pigs. Moreover, histological studies showed a statistically significant (P < 0.05) higher incidence of tissue bleeding in the heparin/aprotinin-treated animals compared with the r-hirudin/aprotinin-treated pigs. Studying the platelet function, a statistically significant (P < 0.01) better preserved ADP- and collagen-induced platelet aggregation was seen in the r-hirudin/aprotinin-treated animals when compared with heparin/aprotinin-treated animals. CONCLUSIONS: These data demonstrate that r-hirudin can be used successfully as an alternative anticoagulant to heparin during cardiac operations including cardiopulmonary bypass. The better preservation of platelet function suggests that r-hirudin may reduce the postoperative risk of bleeding.

Animals↗
PubMed1994

Platelet-activating factor plays an important role in reperfusion injury in myocardium. Efficacy of platelet-activating factor receptor antagonist (CV-3988) as compared with leukocyte-depleted reperfusion.

Although platelet-activating factor has been implicated in the pathogenesis of neutrophil-induced reperfusion injury, it has other mechanisms of direct deleterious hemodynamic effect. In this study we evaluated the definitive role of platelet-activating factor in myocardial reperfusion injury. Porcine hearts that underwent 60 minutes of normothermic ischemia with cardioplegia and 60 minutes of reperfusion under cardiopulmonary bypass were divided into three groups according to the methods of 15 minutes of controlled reperfusion: whole blood reperfusion group (n = 6), leukocyte-depleted reperfusion group (n = 6), and platelet-activating factor receptor antagonist (CV-3988) group (n = 6). At 60 minutes of reperfusion, the percentage of recovery of maximum slope of the pressure-volume relationship measured with intraventricular balloon, malondialdehyde value in coronary sinus blood, tissue adenosine triphosphate, and percentage of spontaneous defibrillation were evaluated. The receptor antagonist group showed significantly better recovery of maximum slope of the pressure-volume relationship than did the whole blood reperfusion group. Moreover, the receptor antagonist group showed significantly less release of malondialdehyde in the coronary sinus, higher values of adenosine triphosphate in the myocardium, and a higher percentage of spontaneous defibrillation than did the whole blood reperfusion group. On the other hand, the leukocyte-depleted reperfusion group showed no significant differences of maximum slope of the pressure-volume relationship, malondialdehyde, adenosine triphosphate, or spontaneous defibrillation as compared with the whole blood group. These results suggest that platelet-activating factor receptor antagonist attenuated severe damage in whole blood reperfusion of the myocardium as compared with leukocyte-depleted reperfusion, which also suggests that platelet-activating factor may play a more important role in myocardial reperfusion injury than do neutrophils.

Animals↗
PubMed1991

In situ localization of transforming growth factor beta 1 in porcine heart: enhanced expression after chronic coronary artery constriction.

We investigated the expression of transforming growth factor beta 1 (TGF-beta 1), a polypeptide differentiation factor probably associated with angiogenic properties in chronically hypoperfused heart tissue. A slowly swelling ameroid constrictor was implanted around the coronary circumflex artery (CX) of young domestic pigs. Two to three weeks after, significant CX stenosis of more than 90% and coronary collateralization could be demonstrated angiographically. The CX dependent experimental myocardial tissue (E) was investigated, with the LAD dependent area of the same pig serving as a control (C). We found significantly enhanced TGF-beta 1 mRNA expression by northern blot hybridization in the experimental myocardium (E) of those pigs with demonstrable coronary collaterals in the absence of a major myocardial infarction. The presence of TGF-beta 1 protein could be demonstrated quantitatively in extracts of the experimental and the control area by immunoblot analysis. By in situ techniques, TGF-beta 1 mRNA and protein could be localized predominantly in cardiac myocytes. We conclude that one adaptive mechanism of the pig heart in chronic coronary artery constriction is the enhanced expression of TGF-beta 1. Cardiac myocytes are a major source of TGF-beta 1. The observed coronary collateralization could be mediated-at least in part-by the angiogenic properties of TGF-beta 1.

Adaptation, Biological↗
PubMed1991

Impairment of the myocardial ultrastructure and changes of the cytoskeleton in dilated cardiomyopathy.

This study was designed to determine the morphological correlate of chronic heart failure. Myocardial tissue from eight patients undergoing transplantation surgery because of end-stage dilated cardiomyopathy was investigated by electron microscopy and immunocytochemistry using monoclonal antibodies against elements of the cytoskeleton: desmin, tubulin, vinculin, and vimentin. The tissue showed hypertrophy, atrophy of myocytes, and an increased amount of fibrosis. Ultrastructural changes consisted of enlargement and varying shape of nuclei, numerous very small mitochondria, proliferation of T tubules, and accumulation of lipid droplets and glycogen. The most obvious ultrastructural alteration was the decrease of myofilaments, ranging from rarefication to complete absence of sarcomeres in cells filled with unspecified cytoplasm. Immunocytochemistry showed that desmin was localized at the Z lines. In diseased myocardium, the amount of desmin was increased, but it was disorderly arranged. Tubulin formed a fine network throughout the myocytes and was significantly increased in cardiomyopathic hearts. Vinculin, a protein closely associated with the cytoskeleton, occurred not only at the sarcolemma and the intercalated disc but also within the myocardial cells. Ultrastructural changes and alterations of the cytoskeleton were severe in about one third of all cells. About one third of all cells showed moderately severe changes, and the remaining cells were normal. Vimentin was present in the interstitial cells and was increased in relation to the increase of fibrosis. We conclude that the increase of fibrosis, the degeneration of hypertrophied myocardial cells, and the alterations of the cytoskeleton are the morphological correlates of reduced myocardial function in chronic heart failure.

Antibodies, Monoclonal↗
PubMed1988

[Surgical aspects of the treatment and significance of angina pectoris].

Due to recent developments in modern interventional cardiology for the majority of patients with multi-vessel disease an indicatory and therapeutical grey-zone between bypass surgery and coronary angioplasty has arisen. Only patients with left main stenosis or uncomplicated one/two-vessel disease are generally accepted to be operated upon or treated by angioplasty, respectively. While pharmacological therapy is somewhat controlled by governments - surgical and cardiological interventional approaches are not. Even if it is justified to work out new interventional therapeutic approaches in the interest of its progress all of our current patients should in any case be informed concerning the risks of their treatment, prior to treatment.

Angina Pectoris↗
PubMed1987

[Heart surgery in acute bacterial endocarditis without preoperative heart catheterization. Long-term observation of 40 patients].

In 40 patients with acute bacterial endocarditis, the indication for cardiac valve replacement was established exclusively on the basis of the echocardiographic and clinical findings. The patients had an average age of 42 years and were under followup observation for an average of 2.2 years. The endocarditis involved the aortic valve 32 times, the mitral valve once, the tricuspid valve in two cases and the aortic and mitral valve together in five cases. In addition to the valve replacement, a ventricular septum defect and aneurysm of the ascending aorta had to be dealt with surgically in two cases each. The intraoperative and perioperative lethality was 2.5% (n = 1). The postoperative lethality was 12.5% (n = 5). In the surviving 34 patients, a recurrence of the endocarditis has not occurred up to now in any case. According to the NYHA classification, six of the surviving patients were to be classified as stage II and 28 as stage I, whereas stage III or IV had been present preoperatively in all cases. The postoperative echocardiographic investigation revealed a significant decrease of the left ventricular enddiastolic diameter (from 61 +/- 8 mm to 51 +/- 5 mm; P less than 0.001). In four cases, a slight insufficiency of the artificial valve could be detected. Reoperation was not necessary in any of these patients.

Adult↗
PubMed1986

[Pleural and mediastinal fibrosis with involvement of the external pericardium as a cause of decompensated heart failure].

Symptoms of cardiac failure were observed in a 60-year-old man 38 years after the therapy of cavernous tuberculosis of the right upper lobe with a paraffin oil plomb. The irritation by the paraffin oil induced a pleural and mediastinal fibrosis involving the pericardium. The rigid pericardium enclosed the heart and caused biventricular cardiac failure by the impaired diastolic filling. Possibilities of medical and surgical treatment are discussed.

Fibrosis↗