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Biomedical subjects

O Wendler

Publications and source records attributed to O Wendler.

30 records · Page 2Linked to original sources
PubMed2000

[Complete arterial revascularization of multivessel coronary disease: are conduits sufficient?].

BACKGROUND: Complete arterial coronary artery bypass grafting seems to be an alternative surgical approach in the treatment of coronary artery disease. Complications in the long-term follow-up due to degeneration of venous grafts may be reduced using arterial conduits. Prolonged operating times and increased trauma due to harvesting of multiple arterial grafts have been arguments for the conventional operative approach. We present our experience using new operative techniques, such as skeletonization of arterial grafts and the T-graft configuration. MATERIAL AND METHODS: Between 3/96 and 7/99, 405 patients with multiple coronary artery disease underwent complete arterial revascularization at our institution. The operations were performed using only two skeletonized grafts, both internal thoracic arteries in 105 patients (25.9%), internal thoracic artery and radial artery in 299 patients (73.8%) and 1 radial artery in 1 patient (0.3%). RESULTS: In 346 patients (85.4%) a T-graft configuration was used. A mean of 4.1 +/- 0.9 coronary anastomoses were performed per patient. In hospital mortality was 2%. Sternal dehiscence or infection occurred in 0.8% of patients. Harvesting of the radial artery was performable with a low morbidity. One week postoperatively, coronary angiography showed 96.7% of coronary anastomoses free of stenosis > 50%. CONCLUSION: Complete arterial coronary revascularization using skeletonized grafts and the T-graft approach is a safe technique in the treatment of multiple coronary artery disease. Low perioperative morbidity and mortality make its usage on a routine basis possible.

Adult↗
PubMed2000

Remodeling of the aortic root and reconstruction of the bicuspid aortic valve.

BACKGROUND: Currently, isolated reconstruction of a regurgitant bicuspid aortic valve can be performed with adequate early results. Dilatation of the proximal aorta is known to be associated with this valve anomaly and may be partially responsible for the development of primary regurgitation or secondary failure of valve repair. We have used repair of the bicuspid valve with remodeling of the aortic root as an alternative to insertion of a composite graft. METHODS: Between October 1995 and May 1999, 16 patients (12 men, 4 women, aged 35 to 73 years) were seen with a regurgitant bicuspid aortic valve and dilatation of the proximal aorta of more than 50 mm. All patients underwent repair of the valve using either coapting sutures alone (n = 12) or in combination with triangular resection of a median raphe (n = 4). Using a Dacron graft, the aortic root was remodeled and the ascending aorta (n = 16) and proximal arch (n = 4) replaced. RESULTS: No patient died. The postoperative degree of aortic regurgitation was less than grade II in all patients. Valve function has remained stable in all patients between 2 and 43 months postoperatively. CONCLUSIONS: Reconstruction of the regurgitant bicuspid valve in the presence of proximal aortic dilatation is feasible with good results by combining the root remodeling technique with valve repair.

Adult↗
PubMed2000

Bronchial and bronchovascular sleeve resection for treatment of central lung tumors.

BACKGROUND: To improve postoperative pulmonary reserve, we have employed parenchyma-sparing resections for central lung tumors irrespective of pulmonary function. The results of lobectomy, pneumonectomy, and sleeve resection were analyzed retrospectively. METHODS: From October 1995 to June 1999, 422 typical lung resections were performed for lung cancer. Of these, 301 were lobectomies (group I), 81 were sleeve resections (group II), and 40 were pneumonectomies (group III). RESULTS: Operative mortality was 2% in group I, 1.2% in group II, and 7.5% in group III (group I and II vs. group III, p<0.03). Mean time of intubation was 1.0+/-4.1 days in group I, 0.9+/-1.3 days in group II, and 3.6+/-11.2 days in group III (groups I and II vs. group III, p<0.01). The incidence of bronchial complications was 1.3% in group I, none in group II, and 7.5% in group III (group I and II vs group III, p<0.001). After 2 years, survival was 64% in group I, 61.9% in group II, and 56.1% in group III (p = NS). Freedom from local disease recurrence was 92.1% in group I, 95.7% in group II, and 90.9% in group III after 2 years (p = NS). CONCLUSIONS: Sleeve resection is a useful surgical option for the treatment of central lung tumors, thus avoiding pneumonectomy with its associated risks. Morbidity, early mortality, long-term survival, and recurrence of disease after sleeve resection are similar to those seen after lobectomy.

Aged↗
PubMed2000

Comparative rest and exercise hemodynamics of 23-mm stentless versus 23-mm stented aortic bioprostheses.

BACKGROUND: The hemodynamic superiority of stentless valves at rest has been generally accepted, but there is a lack of studies on exercise hemodynamics. METHODS: We assessed aortic valve hemodynamics at rest and during exercise in 10 patients with a 23-mm stentless aortic bioprosthesis (Medtronic Freestyle; Medtronic Europe SA/NV, St. Stevens Woluwe, Belgium), in 10 patients with a 23-mm stented aortic bioprosthesis (Carpentier-Edwards, SAV, model 2650; Baxter Edwards AG, Horw, Switzerland), and in 10 healthy volunteers (control group) by means of Doppler echocardiography. RESULTS: Gradients at rest and gradients on comparable maximum exercise levels were significantly lower in patients with stentless valves compared to those with stented valves (rest: 6 +/- 2/11 +/- 4 mm Hg [mean/peak] versus 12 +/- 3/21 +/- 10 mm Hg; exercise: 9 +/- 3/18 +/- 6 mm Hg [mean/peak] versus 22 +/- 8/40 +/- 11 mm Hg). Patients with stentless valves revealed, in comparison to healthy young men, significantly higher gradients, but the small gradient difference of 3/7 mm Hg (mean/peak) at rest remained nearly unchanged throughout the exercise protocol (4/8 mm Hg [mean/peak] at 25 W, 4/9 mm Hg at 50 W and 4/9 mm Hg at 75 W). In contrast, the gradient difference between patients with stented and stentless valves increased significantly from one exercise level to the next (6/12 mm Hg [mean/peak] at rest, 8/14 mm Hg at 25 W, 12/17 mm Hg at 50 W, and 15/25 mm Hg at 75 W). CONCLUSIONS: A stentless aortic bioprosthesis seems to be an appropriate aortic valve substitute, especially in patients who perform regular physical exercise.

Aged↗
PubMed2000

Mitral-valve repair without annuloplasty rings: results after repair of anterior leaflet versus posterior-leaflet defects using polytetrafluoroethylene sutures for chordal replacement.

OBJECTIVE: Defects of the anterior mitral leaflet (AML), including ruptured chordae, are often regarded as difficult or even impossible to repair. Chordal replacement may also be an option in extensive disease of the posterior mitral leaflet (PML). It has not yet been clearly defined whether the repair of either mitral leaflet using chordal-replacement techniques is as safe as the standard repair of the mitral valve (MV) including quadrangular resection and ring reduction alone. METHODS: Between October 1995 and June 1999, 160 patients underwent MV repair for mitral regurgitation (MR) in our institution. Chordal replacement with polytetrafluoroethylene (PTFE) sutures for elongated or ruptured chordae was performed in 72 (45%) patients. These patients were divided into two groups according to the location of the MV lesions: 48 patients with prolapse of the anterior or both leaflets (AML group) received an average of 2.2+/-1. 1 PTFE sutures for repair; in 24 patients with isolated PML defects (PML group), we used an average of 1.5+/-0.8 PTFE sutures. No prosthetic annuloplasty rings were used. Dilatation of the posterior mitral ring was corrected by PTFE suture annuloplasty. The remaining 88 patients underwent a standard mitral repair without chordal replacement. There were no statistically significant (NS) differences between the two groups (AML/PML) regarding age (59/62 years, P=0.49), left ventricular (LV) ejection fraction (64/66%, P=0. 6) and preoperative NYHA class (2.9/2.9, P=0.36). Postoperatively, all patients were followed by serial transthoracic echocardiography at 1 week and after 3, 6, 12 and 24 months by the same investigator. RESULTS: In-hospital mortality was 4.2% (2/48) in the AML group and 0% (0/24) in the PML group (P=0.55). Three of the AML patients (6. 3%) and one PML patient (4.2%) underwent reoperation for recurrent MR (P=1.0). The 1- and 2-year freedom from MV reoperation was 95. 1+/-3.4 and 92.6+/-4.2% in the AML group versus 95.0+/-4.9 and 95. 0+/-4.9% (P=0.67). The 1- and 2-year freedom from residual or recurrent MR grade 2 or higher was 97.6+/-2.4 and 94.9+/-3.5% (AML) versus 95.8+/-4.0 and 95.8+/-4.0% (PML) (P=0.97). CONCLUSIONS: We were unable to find statistically significant differences concerning mortality, freedom from recurrent MR and MV reoperation between the AML and PML groups. Extensive prolapse or chordal pathology of the anterior and PML can be corrected by chordal replacement. Using these techniques, stable repair can be achieved in more than 90% of patients at mid-term follow-up. Long-term observations are necessary to confirm the durability of this type of MV repair.

Adult↗
PubMed2000

Complete arterial revascularization using T-graft technique in diabetics with coronary three-vessel disease.

BACKGROUND: Coronary revascularization using exclusively arterial grafts holds the promise of improved long-term patency. The T-graft approach achieves this goal with only two arterial grafts in coronary 3-vessel disease. Arterial grafts in diabetics, however, exhibit more frequently atherosclerotic wall abnormalities, and higher levels of endothelin-1 were found in diabetic arterial grafts, which may be associated with a higher incidence of vasoconstriction. The objective of this prospective study was to compare functional und angiographic parameters of arterial T-grafts in diabetics and nondiabetics. METHODS: Coronary angiography was performed consecutively in 20 patients with insulin-dependent diabetes mellitus (IDDM), 20 patients with non-insulin-dependent diabetes mellitus (NIDDM), and 100 non-diabetics one week after complete arterial revascularization with T-grafts. Graft patency was assessed, and the diameter of the proximal left internal mammary artery (IMA) graft was measured using quantitative coronary analysis. Absolute flow volume in the proximal left IMA was measured using the flow-wire technique at baseline and after an adenosine injection into the graft to induce maximal hyperemia. Coronary flow reserve (CFR) was calculated as the ratio of maximal to baseline flow. RESULTS: There was no difference between patients with IDDM, patients with NIDDM and non-diabetics with respect to patency (98.3% vs. 98.8% vs. 97,8%, n.s.), graft lumen diameter (3.42 +/- 0.48 vs. 3.36 +/- 0.50 vs. 3.38 +/- 0.41 mm, n.s.), baseline flow (78.4 +/- 34.3 vs. 83.1 +/- 36.6 vs. 81.5 +/- 39.0 ml/min, n.s.), and CFR (1.85 +/- 0.37 vs. 1.89 +/- 0.44 vs. 1.90 +/- 0.40, n.s.). CONCLUSION: Baseline parameters (graft diameter and quantitative graft flow), patency and CFR are identical in diabetics and non-diabetics. Our results suggest that diabetic patients with coronary 3-vessel disease take comparable profit from complete arterial revascularization using the T-graft technique as non-diabetics.

Cardiac Catheterization↗
PubMed2000

Endotoxin desensitization of human mononuclear cells after cardiopulmonary bypass: role of humoral factors.

BACKGROUND: The ability of leukocytes to release proinflammatory cytokines on lipopolysaccharide stimulation in vitro is impaired after cardiopulmonary bypass (CPB). This study tested contribution and interaction of humoral factors in altered leukocyte responsiveness to lipopolysaccharide. METHODS: Whole blood and isolated peripheral-blood mononuclear cells (PBMCs) from 10 patients obtained after induction of anesthesia (T1) and 20 min (T2) and 24 h (T3) after CPB were cultured in the absence or presence of lipopolysaccharide and assessed for release of tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-1beta and their functional antagonists, IL-1 receptor antagonist (IL-1ra) and IL-10. In addition, dose-response characteristics and interaction of IL-10 and norepinephrine as modulators of TNF-alpha release were studied. RESULTS: Cardiopulmonary bypass induced release of antiinflammatory (T2: IL-10: median 25 pg/ml, 25th-75th percentile 9-42; IL-1ra: median 1,528 pg/ml, 25th-75th percentile 1,075-17,047; P < 0.05 compared with T1) but failed to induce proinflammatory cytokines (T2: TNF-alpha: median 0 pg/ml, 25th-75th percentile 0-6; IL-1beta: median 1 pg/ml, 25th-75th percentile 0-81; nonsignificant). Removal of plasma at T2 increased TNF-alpha response to lipopolysaccharide (+83.8%; P < 0.05), whereas it suppressed IL-10 (-36.8%; P < 0.05). Similarly, incubation of PBMCs (T1) with plasma obtained after CPB (T2) as well as addition of IL-10 or norepinephrine in concentrations present in plasma after CPB led to a reduced lipopolysaccharide-stimulated TNF-alpha and an increased IL-10 response. Coadministration of norepinephrine and IL-10 had synergistic effects. Although pretreatment with an anti-IL-10 antibody and labetalol before addition of plasma obtained at T2 largely restored the TNF-alpha response in vitro, their addition post-treatment failed to restore the monocytic TNF-alpha response. CONCLUSIONS: Plasma contains interacting factors that inhibit the release of TNF-alpha and increase the release of IL-10, presumably attenuating the inflammatory response to CPB. Although norepinephrine fails to induce a cytokine response in the absence of other stimuli, its administration seems to augment the antiinflammatory IL-10 response while attenuating the TNF-alpha response.

Adult↗
PubMed1999

T grafts with the right internal thoracic artery to left internal thoracic artery versus the left internal thoracic artery and radial artery: flow dynamics in the internal thoracic artery main stem.

OBJECTIVE: Complete arterial coronary artery bypass grafting with 2 grafts can be achieved even in triple vessel disease by use of a T configuration. There is still uncertainty whether the coronary flow reserve in the main stem of the left internal thoracic artery is sufficient to supply more than 1 anastomosed coronary vessel. METHODS: Between March 1996 and February 1999, 251 patients with multivessel coronary artery disease underwent complete arterial revascularization with T grafts, using either the left internal thoracic artery with the free right internal thoracic artery graft (n = 73, group I) or the left internal thoracic artery and radial artery (n = 178, group II). A mean of 4.0 (group I) versus 4.3 (group II) coronary vessels were anastomosed per patient. One week (n = 92) and 6 months (n = 28) after the operation, flow was measured in the proximal left internal thoracic artery with a Doppler guide wire. Maximum flow was determined after injection of adenosine (30 microg). RESULTS: The in-hospital mortality was 2.7% (group I) versus 2.3% (group II). At angiography (n = 142, 56.6%) the patency rate was 96.3% (group I) versus 98.2% (group II). There was no significant difference between baseline flow, maximum flow, and coronary flow reserve between the 2 groups. Coronary flow reserve increased in both groups within the first 6 postoperative months (group I, 1.85 +/- 0.31 vs 2.77 +/- 0.77, P =.0002; group II, 1.82 +/- 0.4 vs 2.53 +/- 0.73, P =.009). CONCLUSION: Both variants of T grafts allow for complete arterial revascularization with good perioperative results. The flow reserve of the proximal internal thoracic artery is adequate for multiple coronary anastomoses irrespective of the choice of the second arterial graft.

Blood Flow Velocity↗
PubMed1999

Free flow capacity of skeletonized versus pedicled internal thoracic artery grafts in coronary artery bypass grafts.

OBJECTIVE: The internal thoracic artery (ITA) is the ideal conduit for coronary artery bypass grafting (CABG). The skeletonization technique of this arterial conduit has been proposed to reduce chest wall trauma, increase graft length and facilitate construction of sequential anastomoses. Nevertheless, some surgeons decline this technique because of potentially increased trauma to the ITA with impairment of flow. In this investigation we compared the free flow of skeletonized with that of pedicled ITA grafts. METHODS: Two surgeons operated on 80 consecutive patients with coronary artery disease for elective CABG. In group I (n = 40), the left ITA was dissected using the skeletonization technique. In group II (n = 40), it was harvested as a pedicled graft. In 23 patients of group I both ITA's were dissected in skeletonized fashion for complete arterial revascularization. Diluted papaverine was instilled into the lumen of the ITA after distal transection of the vessel in both groups. Free flow of the ITA was registered before and 15 min after intraluminal application of diluted papaverine. Mean arterial pressure was maintained at 70 mmHg. RESULTS: Before the application of papaverine, free flow of skeletonized and pedicled ITA grafts was identical between the two groups. After treatment with papaverine maximum free flow was significantly higher in the skeletonized ITA's (group I 197.2 (+/-66.6) ml/min; group II 147.1 (+/-70.5) ml/min; P < 0.05). There was no significant difference between free flow after dilatation of the left and right ITA in group I (left 197.2 (+/-66.6) ml/min; right 198.9 (+/-61.8) ml/min). CONCLUSIONS: Preparation of the ITA with the skeletonization technique results in significantly, higher free flow capacity than in pedicled grafts. This may increase the safety of arterial revascularization by reducing the risk of ITA hypoperfusion syndrome.

Aged↗
PubMed1998

[Treatment of the aortic valve and ascending aorta. The significance of reconstructive methods on the aortic root].

BACKGROUND AND OBJECTIVE: The standard surgical repair of disease of the aortic valve and the ascending aorta has been combined replacement, which includes the disadvantage of inserting a mechanical valve. We have investigated an individualized approach which preserves the native valve. PATIENTS AND METHODS: Between October 1995 and October 1997, a consecutive total of 101 patients (72 men, 29 women, aged 21-83 years) underwent operations for disease of the ascending aorta: aortic dissection type A in 34 patients, aneurysmal dilatation in 67. Dilatation of the aortic arch was associated with aortic regurgitation in 58 patients. There were 11 patients with aortic valve stenosis or previously implanted aortic valve prosthesis among a total of 46 whose aortic valve was replaced (group II). Supracommissural aortic replacement with a Dacron tube was performed in 16 patients (group I) with normal valve cusps and an aortic root diameter < 3.5 cm. In 28 patients with an aortic root diameter of 3.5-5.0 cm the aortic root was remodelled (group III). Resuspension of the native aortic valve was undertaken in 11 patients with aortic root dilatation of > 5.0 cm (group IV). RESULTS: Operative intervention was electively performed in 72 patients, without any death. Of 29 patients operated as an emergency for acute type A dissection four died (14%). In 55 of the 58 patients with aortic regurgitation in proved possible to preserve native aortic valve (95%). In the early postoperative phase and after an average follow-up time of 11.8 months, transthoracic echocardiography demonstrated good aortic valve function, except in one patient each of groups III and IV who developed aortic regurgitation grades I or II. CONCLUSION: The described individualized approach makes it possible to preserve the native aortic valve in most patients with aortic regurgitation, at a low risk. Follow-up observations so far indicate good results of the reconstruction.

Adult↗
PubMed1998

Arthritis-related B cell epitopes in collagen II are conformation-dependent and sterically privileged in accessible sites of cartilage collagen fibrils.

In collagen-induced arthritis, a murine autoimmune model for rheumatoid arthritis, immunization with native but not heat-denatured cartilage-specific collagen type II (CII) induces a B cell response that largely contributes to arthritogenicity. Previously, we have shown that monoclonal antibodies established from arthritis prone DBA/1 mice require the triple-helical conformation of their epitopes for antigen recognition. Here, we present a novel approach to characterize arthritis-related conformational epitopes by preparing a panel of 130 chimeric collagen X/CII molecules. The insertion of a series of CII cassettes into the triple-helical recombinant collagen X allowed for the first time the identification of five triple-helical immunodominant domains of 5-11 amino acid length, to which 75% of 36 monoclonal antibodies bound. A consensus motif, "R G hydrophobic," was found in all immunodominant epitopes. The antibodies were encoded by a certain combination of V-genes in germline configuration, indicating a role of the consensus motif in V-gene selection. The immunodominant domains are spread over the entire monomeric CII molecule with no apparent order; however, a highly organized arrangement became apparent when the CII molecules were displayed in the quarter-staggered assembly within a fibril. This discrete epitope organization most likely reflects structural constraints that restrict the exposure of CII epitopes on the surface of heterotypically assembled cartilage fibrils. Thus, our data suggest a preimmune B cell selection process that is biased by the accessibility of CII determinants in the intact cartilage tissue.

Animals↗