Biomedical subjects

J F Bechtel

Publications and source records attributed to J F Bechtel.

10 recordsLinked to original sources

PubMed2005

[Aortic valve operation in young adults].

Young adults who have to undergo aortic valve surgery will frequently have (relative) contraindications to oral anticoagulation therapy because either pregnancy is planned or their life-style is very active. This review focuses on the surgical options available and assesses the literature focusing on the experience with each option obtained in young adults. There are no randomized studies in this age group which compare mechanical aortic valve replacement with any alternative option with regard to survival, need for reoperation, or quality of life. Among the alternative techniques, the Ross-procedure (pulmonary autograft) and aortic valve repair are of special interest. With the Ross-procedure, there is a rather large experience in young adults, and the results up to 10 years postoperatively are excellent. Unfortunately, there is only limited experience with this technique beyond that time.

Abnormalities, Drug-Induced↗

PubMed2001

Does histocompatibility affect homograft valve function after the Ross procedure?

BACKGROUND: Homograft valves have been shown to be immunogenic, but it is unknown whether this affects valve function. Therefore, we prospectively studied the degree of histoincompatibility (defined as the number of human leukocyte antigen [HLA] mismatches between valve donor and recipient) and the response of the recipient (measured by antibodies against HLA) in relation to echocardiographic parameters of homograft valve function after the Ross procedure. METHODS AND RESULTS: Twenty-six patients (mean age 41+/-14 years; 20 males, 6 females) and the cryopreserved pulmonary homograft valves that were implanted during a Ross procedure were typed for HLA-A, HLA-B, and HLA-DR. After a mean follow-up of 15+/-6 months, 14 (54%) of the patients were anti-HLA class I antibody positive. In all but 1 patient, these antibodies were shown to be donor specific. During follow-up, there was a significant increase of the maximal (+6.2+/-7.1 mm Hg) and mean (+3.2+/-4.3 mm Hg) transhomograft pressure gradients but not of homograft regurgitation. Neither the number of HLA mismatches nor antibody status was found to have significant impact on homograft valve function. In a multivariate analysis, smaller homograft size (P=0.001) and younger recipient age (P=0.044) were shown to be significantly associated with increased transhomograft pressure gradients. CONCLUSIONS: Implantation of a cryopreserved pulmonary homograft during the Ross procedure can induce a specific humoral response. We observed a significant increase of the transhomograft pressure gradients within 15+/-6 months after surgery. For this period, we were unable to demonstrate a relationship between this increase and the degree of histoincompatibility.

Adult↗

PubMed2001

Anti-HLA class I antibodies and pulmonary homograft function after the Ross procedure.

BACKGROUND: The Ross procedure provides excellent long-term results in the majority of patients. However, degeneration of the pulmonary homograft in some patients remains an unresolved problem that may be related to immunologic factors. Therefore, we studied the prevalence of antihuman leukocyte antigen (HLA) class I antibodies and echocardiographic results of homograft function at rest. METHODS: Forty-seven patients (37 men, 10 women; 47 +/- 15 years) were seen for echocardiography 1.1 to 63.9 months (median, 27 months) postoperatively. The presence of anti-HLA antibodies was tested against a panel of lymphocytes of 50 donors. RESULTS: Twenty-seven (57%) of the patients produced anti-HLA class I antibodies. No difference in the maximal or mean transhomograft pressure gradient, or in the frequency of homograft regurgitation according to the presence or absence of anti-HLA antibodies was found. However, the right ventricle was slightly but significantly larger in antibody-positive patients (26.3 +/- 4.2 versus 30.7 +/- 3.5 mm; p = 0.001). CONCLUSIONS: In the first years after the Ross procedure, we could not detect significant evidence of an association between anti-HLA class I antibodies and echocardiographic results of homograft function at rest in adults.

Adult↗

PubMed2001

Influence of modified ultrafiltration on coagulation, fibrinolysis and blood loss in adult cardiac surgery.

OBJECTIVES: Modified ultrafiltration (MUF) significantly reduce blood loss and transfusion requirements in pediatric cardiac surgery presumably by a reduction in inflammatory mediators which decrease the inflammatory axes and decrease the cross-activation of fibrinolysis and thrombosis. The influence of MUF on blood loss and homologous blood transfusion in adult cardiac surgery has not yet been determined. Furthermore, data about the influence on routine coagulation tests, platelet activation as well as the coagulation and fibrinolytic systems are limited. METHODS: In a prospective randomized study 48 patients scheduled for elective myocardial revascularization were randomized into a control group (n=16), a conventional ultrafiltration (CUF) group (n=16) and a MUF group (n=16). Perioperatively, serial blood samples were drawn at specific intervals to evaluate coagulation, fibrinolysis, and platelet function. RESULTS: Neither the coagulation nor the fibrinolytic system was positively influenced by MUF or CUF. The routine clotting tests were comparable except for a significantly higher antithrombin III activity after MUF compared to the CUF control group persisting 24 h postoperatively. Platelet factor 4 activity and platelet counts showed no differences among the groups. MUF considerably reduced the postoperative blood loss (MUF, 6.4+/-1.7 ml/kg bw per 24 h vs. CUF, 9.2+/-2.5 ml/kg bw per 24 h (P=0.003) vs. control, 8.9+/-2.2 ml/kg bw per 24 h (P=0.008)) and allogeneic blood transfusion (MUF, 2.0+/-3.4 ml/kg bw per 24 h vs. CUF, 6.9+/-5.1 ml/kg bw per 24 h (P=0.034) vs. control, 7.0+/-6.3 ml/kg bw per 24 h (P=0.029)). CONCLUSIONS: MUF in adult cardiac surgery significantly reduces postoperative blood loss and transfusion requirements. The mechanism for reduced blood loss could not be elucidated in this study.

Antithrombin III↗

PubMed2000

Association of serology with the endovascular presence of Chlamydia pneumoniae and cytomegalovirus in coronary artery and vein graft disease.

BACKGROUND: Chemotherapeutic treatment for patients with symptomatic coronary artery disease to reduce cardiovascular events may be initiated in response to elevated antibody titers against Chlamydia pneumoniae or cytomegalovirus. How antibody titers are associated with the endovascular presence of these microorganisms is still unclear. METHODS AND RESULTS: Antibody titers against C pneumoniae (microimmunofluorescence) and cytomegalovirus (ELISA) in patients undergoing primary (coronary desobliterates, n=80) or repeated CABG (occluded vein grafts, n=45) were correlated with the endovascular presence of the 2 microorganisms. C pneumoniae was detected by means of a nested polymerase chain reaction (PCR) and by culturing. Both conventional PCR and quantitative PCR were applied for detection of cytomegalovirus. C pneumoniae (PCR/culture) was detected in 19/9% (15/80 and 7/80) of coronary desobliterates and in 18/11% (8/45 and 5/45) of occluded vein grafts. There was no statistical evidence that IgG values differed between patients with or without C pneumoniae detection who were undergoing primary CABG. In contrast, repeated-CABG patients with a positive PCR (P=0.0027) or C pneumoniae culture (P=0.0018) had distinctly elevated IgG titers compared with patients in whom C pneumoniae was not detected. Cytomegalovirus could not be detected in the examined specimens. CONCLUSIONS: Cytomegalovirus infection does not seem to be associated with advanced coronary artery lesions. C pneumoniae antibody titers are not associated with the endovascular presence of C pneumoniae in patients with coronary artery disease. The observed strong association between elevated IgG titers and the detection of C pneumoniae in occluded vein grafts warrants further investigation.

Aged↗

PubMed2000

[Intermediate term clinical results after endoaneurysmorrhaphy in left ventricular aneurysm].

Endoaneurysmorrhaphy (EAR) in postinfarct ventricular aneurysms leads to excellent short-term results. However, the temporal response of EAR is widely unknown. Thus, the indication for surgical treatment of patients with ventricular aneurysms is not well defined. EAR was performed in 157 patients (6/1993-6/1999) with symptomatic ventricular aneurysms (median NYHA III). Factors influencing cardiac mortality and morbidity during follow-up were determined by univariate and multivariate analysis. Perioperative mortality was low: 5%. Mortality during follow-up was 3.3% per year, resulting in a 5-year survival rate of 78%. NYHA classification ameliorated significantly from the preoperative status compared to the follow-up period (median NYHA II; p < 0.001). Multivariate analysis identified preexisting arterial occlusive disease and advanced age (> 70 years) as significant factors influencing medium-term mortality. Implantation of the left internal mammary artery was associated with a better survival rate. Endoaneurysmorrhaphy can be performed with low perioperative mortality, will result in a significant amelioration of the cardiac clinical status and offers low medium-term mortality. Our data indicate that EAR seems to be the procedure of choice for patients with symptomatic ventricular aneurysms.

Aged↗

PubMed2000

Up to seven years of experience with the Ross procedure in patients >60 years of age.

OBJECTIVES: The objective of this study was to compare the outcome of patients >60 years of age with younger patients after the Ross procedure. BACKGROUND: Currently, the Ross procedure is performed predominantly in young patients. Main arguments against the Ross procedure in the elderly are the complexity of the operation and related risks. Experience with the Ross procedure in patients >60 years of age is scarce. METHODS: Between February 1990 and August 1998, the Ross procedure was performed in 27 patients (15 men and 12 women) >60 years of age (mean 64.2 +/- 3.1 years, range 60.5 to 70.6; group A) and in 84 patients (68 men, 12 women) <60 years of age (mean 43.8 +/- 12.4 years, range 15.2 to 59.4; group B). Echocardiography was applied at a mean follow-up of 28.4 +/- 21.0 and 25.2 +/- 21.4 months, respectively, to determine hemodynamic variables (ejection fraction, fractional shortening, stroke volume, cardiac output), cardiac dimensions and autograft and homograft valve function. RESULTS: There was one early and one late (esophageal bleeding) death in group B; the mortality rate was 0% in group A. One autograft was replaced because of a subvalvular aneurysm, and one patient was lost to follow-up (group B). There were no significant differences in cardiac dimensions, grade of insufficiencies across homografts and autografts and hemodynamic variables, except for a higher pressure gradient across the homograft in group B (maximal pressure gradient 11.3 +/- 5.6 vs. 7.7 +/- 4.6 mm Hg in group A). The median New York Heart Association functional class was I in both groups. CONCLUSIONS: Our seven years of experiences (mean follow-up 28 months) indicate that the Ross procedure may be performed in selected patients >60 years of age without increased risk for mortality or complications in experienced centers.

Adolescent↗

PubMed2000

Carotid endarterectomy prior to major abdominal aortic surgery.

BACKGROUND: Major aortic surgery carries a high risk of stroke. Carotid artery occlusive disease (CAOD) has been identified as one of the contributing risk factors. Regarding the long-term prevention of stroke, carotid endartectomy (CEA) seems to be superior to the best medical treatment in patients with high-grade CAOD. However, the role of CEA prior to major aortic surgery has not been studied. METHODS DESIGN: Prospective study, observational design. SUBJECTS AND SETTING: 201 patients referred to a community hospital for major aortic surgery. INTERVENTION: The patients were non-invasively screened by continuous-wave and duplex Doppler ultrasonography for the presence of CAOD. In 41 patients with angiographically confirmed high-grade CAOD, CEA was performed prior to major aortic surgery. MAIN OUTCOME MEASURE: Combined mortality and major morbidity from CEA and abdominal aortic surgery. RESULTS: There was no mortality or morbidity related to CEA. Total perioperative mortality related to major aortic reconstruction was 3.5%. No new perioperative focal neurologic deficits occurred except for one fatal stroke in a patient in whom CEA had been judged not to be indicated. CONCLUSIONS: CEA can be performed safely prior to major aortic surgery resulting in excellent overall neurologic outcome in patients with high-grade CAOD. We propose that patients scheduled for major aortic surgery be screened for the presence of high-grade CAOD and that CEA be performed first, if indicated according to published guidelines.

Adult↗

PubMed1999

Detection of Chlamydia pneumoniae but not cytomegalovirus in occluded saphenous vein coronary artery bypass grafts.

BACKGROUND: A causal relation between atherosclerosis and chronic infection with Chlamydia pneumoniae and/or cytomegalovirus (CMV) has been suggested. Whether the unresolved problem of venous coronary artery bypass graft occlusion is related to infection with C pneumoniae and/or CMV has not been addressed. METHODS AND RESULTS: Thirty-eight occluded coronary artery vein grafts and 20 native saphenous veins were examined. Detection of C pneumoniae DNA was performed by use of nested polymerase chain reaction (PCR). Homogenisates from the specimen were cultured for identification of viable C pneumoniae. Both conventional PCR and quantitative PCR for detection of CMV DNA were applied. Differential pathological changes (degree of inflammation, smooth muscle cell proliferation [MIB-1]) were determined and correlated to the detection of both microorganisms. C pneumoniae DNA could be detected in 25% of occluded vein grafts. Viable C pneumoniae was recovered from 16% of occluded vein grafts. Except for 1 native saphenous vein, all control vessels were negative for both C pneumoniae detection and culture. All pathological and control specimens were negative for CMV DNA detection. Pathological changes did not correlate with C pneumoniae detection. CONCLUSIONS: Occluded aorto-coronary venous grafts harbor C pneumoniae but not CMV. The detection of C pneumoniae in occluded vein grafts warrants further investigation.

Adult↗

PubMed1997

Cardiac risk stratification for high-risk vascular surgery.

BACKGROUND: The best strategy for cardiac risk assessment before high-risk vascular surgery remains controversial. A cardiac risk stratification protocol was evaluated in patients undergoing high-risk vascular surgery. Our investigation paralleled the elaboration of the American College of Cardiology/ American Heart Association (ACC/AHA) Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery and is highly comparable to the proposed guidelines. METHODS AND RESULTS: A cardiac risk stratification protocol was evaluated prospectively in 203 patients scheduled for aortic surgery. Key points of the study were cardiac mortality/morbidity and cost-effectiveness. Patients were stratified into low (n = 101), intermediate (n = 79), and high (n = 23) cardiac risk after clinical predictors. After stratification, the degree of estimated functional capacity assessed by treadmill exercise and daily living activities and expressed by metabolic equivalents (METs) was critical for further cardiac evaluation. In intermediate-risk patients with an estimated functional capacity < 5 METs and in all high-risk patients, noninvasive cardiac testing and/or subsequent medical care were performed. Noninvasive testing was considered necessary in 41 patients, coronary angiography in 7, and myocardial revascularization in 1. Overall hospital mortality was 3.5%. Cardiac mortality and morbidity were 1% and 12.4%, respectively. CONCLUSIONS: Cardiac risk stratification for high-risk vascular surgery patients, according to a protocol similar to the ACC/AHA Guidelines for Cardiovascular Evaluation for Noncardiac Surgery, demonstrated excellent clinical outcome. This approach appears to be a safe and economical strategy for preoperative cardiac evaluation.

Aorta↗