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Biomedical subjects

E Bos

Publications and source records attributed to E Bos.

At least 109 records · Page 6Linked to original sources
PubMed1991

Early surgery for active infective endocarditis improves early and late results.

To investigate the timing of surgery in active infective endocarditis, the data of 54 patients, consecutively operated for this reason from September 1973 to May 1989, were analysed. Native valves were involved in 31 patients (57%): the aortic valve in 22, the mitral valve in 6, and both valves in 3 cases. Prosthetic valves were involved in 23 patients (43%): the aortic valve in 14, the mitral valve in 7, and both valves in 2 cases. There were no significant differences between involvement of native or prosthetic valves and mortality, morbidity, or consequences of morbidity. No significant correlation was found between causative microorganism and mortality, morbidity, or consequences of morbidity. The indication for operation was cardiac failure in 15 patients (28%), ongoing infection in 24 (44%) or a combination of these in 15 (28%). Major embolization occurred in 12 patients (22%) and affected women more than men (p = 0.05). Hospital mortality was 8 (15%). Morbidity involved 15 more patients; structural deterioration of the valve prosthesis occurred in 1 patient; nonstructural dysfunction of the valve prosthesis occurred 11 times in 10 patients; anticoagulation-related hemorrhage involved 2 patients (1 with nonstructural dysfunction of the valve prosthesis); endocarditis was diagnosed in 3 patients. The consequences of these morbid events concerned 14 patients; reoperations were done 9 times in 8 patients; mortality was valve related in 6 cases. Because 2 more patients died during the course of the study, total late mortality was 8. Probability of survival 5 years after operation was 72% (95% cl 56-83) and at 10 years 47% (95% cl 21-70).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Role of intraoperative ultrasound examination in patients undergoing a Fontan-type procedure.

To determine its potential impact on perioperative surgical management intraoperative ultrasound examination (cross sectional imaging, colour flow mapping, pulsed and continuous wave Doppler) was used in 16 consecutive patients undergoing a Fontan-type procedure. Epicardial cross sectional imaging before bypass defined the precise intracardiac morphology in 15 of 16 patients. The preoperative morphological diagnosis was refined in four patients (25%), and this influenced surgical management in two (12%). Epicardial studies after bypass identified seven residual haemodynamic lesions in five patients (three residual intercardiac shunts, one ventricular outflow obstruction, one pulmonary artery obstruction, two mitral valve regurgitation), and led to immediate revision during a second period of bypass in three (18%). In one patient who required early reoperation residual shunting was not detected after bypass by either colour flow mapping or a contrast study. Final intraoperative studies showed a good surgical result in 14 patients (87%). Flow characteristics and flow velocities within the Fontan circulation could be assessed immediately after the patient came off cardiopulmonary bypass by means of combined pulsed wave Doppler and colour flow mapping in 14 of the 16 patients. Cross sectional studies of the left heart after bypass showed no change in ventricular function and allowed monitoring of volume replacement and ventricular filling. Intraoperative ultrasound was a valuable monitoring technique in patients undergoing a Fontan-type procedure. It refined preoperative diagnosis, monitored ventricular function, and identified or excluded residual haemodynamic lesions in most patients.

Adult↗
PubMed1991

Does xanthine oxidase cause damage during myocardial ischemia?

Xanthine oxidase is the pathological form of xanthine oxidoreductase, which generates free oxygen radicals, when it converts (hypo)xanthine to urate. We studied 1. developmental changes in rat heart, 2. urate production in catheterized patients, and 3. species differences of cardiac xanthine oxidase. First, we measured the activity of the enzyme at various ages. In rat-heart homogenate, xanthine oxidoreductase increased from 0.5 mU/g (newborn) to 25 mU/g (15 weeks, P less than 0.001). In the second part of the study, we demonstrated that patients undergoing coronary angioplasty showed some cardiac urate production. In the last part of our investigations we showed that in explanted human hearts perfused with hypoxanthine, the enzymatic activity was low, contrasting findings in some other species. The apparent xanthine oxidoreductase activity (mU/g) was: 33 (mouse), 28 (rat), 14 (guinea pig), 0.59 (rabbit), less than 0.1 (pig), 0.31 (man) and 3.7 (cow). We conclude that in several species, cardiac damage due to xanthine oxidase cannot be excluded; however in man it is unlikely to occur.

Aging↗
PubMed1991

Clinical outcome of single versus sequential grafts in coronary bypass operations at ten years' follow-up.

To evaluate the long-term outcome of the sequential aorta-coronary bypass grafting technique, we compared the results in 234 patients with single venous grafts (group I) with those of 234 patients with predominantly sequential grafts (group II). All were symptomatic for angina pectoris before operation and had either three-vessel or left main stem coronary artery disease. Operations were performed from March 1975 to June 1980. The mean follow-up period was 10.5 years (minimum 8.5; maximum 13.6). The perioperative mortality rate in group I was 3% and in group II, 1% (not significant). The survival probability at 5 years after operation for group I was 90% +/- 2% and for group II, 88% +/- 2%; at 10 years, 71% +/- 3% and 72% +/- 3%, respectively. Multivariate analysis elicited no risk difference related to graft type: group II versus group I hazard ratio, 0.82; 95% confidence interval 0.58 to 1.16 (not significant). Regarding depressed left ventricular function versus normal function, an increased risk was observed: 1.9 (95% confidence interval 1.35 to 2.75), as was the case for advanced age: 60 years or more versus less than 60 years, 1.6 (1.1 to 3.5). Thus the sequential venous grafting technique seems to have the same 10-year results as single venous grafts.

Cause of Death↗
PubMed1990

Subaortic obstruction: intraoperative echocardiography as an adjunct to operation.

Fourteen patients undergoing operation for subaortic obstruction (membranous obstruction in 11 patients, tunnel obstruction in 2 patients, obstruction due to reduplicated mitral valve tissue in 1 patient) were evaluated by intraoperative epicardial echocardiography. In all 9 patients with "discrete" obstruction who underwent prebypass epicardial echocardiography, the septal and lateral attachments of the lesion were correctly demonstrated. The precise extent of tunnel stenosis was seen in both patients. The lateral attachment of the membrane in 4 patients and multiple extensions in another 2 were identified by the epicardial study (having been missed on precordial echocardiography). The discrete membrane was enucleated in 10 of the 11 patients and was partially resected in 1. One tunnel obstruction was completely relieved; the other was partially relieved. Reduplicated mitral valve tissue in the remaining patient was completely resected. Epicardial imaging after bypass showed remnants of the membrane in 2 patients. Intraoperative Doppler echocardiography and color flow imaging confirmed the absence of clinically significant residual gradients (less than 20 mm Hg) in all but 1 patient with tunnel obstruction. Epicardial imaging provided excellent morphological information about obstructive lesions of the left ventricular outflow tract and enabled immediate assessment of surgical repair.

Aortic Valve Stenosis↗
PubMed1990

gamma delta T-cell receptor-positive T-cell clones derived from human heart transplants do not show donor-specific cytotoxicity.

gamma delta T-cell receptor-positive T-cell clones were obtained from three endomyocardial biopsies taken from two patients. Clones obtained from two biopsies from patient A, one taken during rejection and one after resolution of this rejection, were WT31-, 11F2+, Ti gamma A-, delta TcS1+. Clones from patient B grown from a biopsy without histologic signs of rejection were either WT31-, 11F2+, Ti gamma A+, delta TcS1-, or WT31+. All gamma delta T-cell receptor-positive clones had cytolytic potential but did not demonstrate donor-specific lysis.

Biopsy↗
PubMed1990

Determinants of survival after surgery for mitral valve regurgitation in patients with and without coronary artery disease.

Mortality and its determinants were assessed in 181 consecutive patients undergoing primary mitral valve surgery for pure mitral regurgitation with coronary artery disease (MR + CAD, 79 patients) or without (MR no CAD, 102 patients). Early mortality (C10% vs. 3%) and 6-year estimate of survival (55% +/- 7.1% vs. 82% +/- 4.4%) were significantly different. Mortality was not significantly different in patients with CAD + MR of an ischemic (49 patients) or a non-ischemic etiology (30 patients). Multivariate testing using Cox regression models of overall mortality in patients with MR + CAD indicated that preoperative renal dysfunction, high right atrial pressure, ejection fraction less than 45% as well as qualitatively reduced left ventricular function and left ventricular end-diastolic volume index greater than 120 ml/m2 are associated with decreased survival. Multivariate testing in patients with MR no CAD only identified insertion of a mechanical prosthesis and a degenerative etiology of mitral valve disease as independent predictors of survival. Thus, a common denominator of preoperative pathology (renal dysfunction) and indices of right and left ventricular dysfunction determined overall survival of patients with MR + CAD. Survival of patients with MR no CAD was determined by the valve prosthesis and the etiology of valve disease.

Coronary Disease↗
PubMed1990

Comparison of costs of percutaneous transluminal coronary angioplasty and coronary bypass surgery for patients with angina pectoris.

To determine the costs of a procedure, the total costs of the department that provides the service must be considered and, in addition, the direct cost of the specific procedure. Applying this principle to the cost accounting of angioplasty and bypass surgery results in a direct, i.e. procedural, cost, including the initial hospital stay, of respectively 8694 Dfl and 20,987 Dfl. A review of the follow-up data for the first year after the original intervention revealed a 2% reintervention rate for bypass surgery, while this percentage was 29% for angioplasty. Adding the first year costs involved with reinterventions to the procedural costs results in a 1-year cost of angioplasty and bypass operation of 13,625 Dfl and 21,363 Dfl, respectively. It is concluded that because of reinterventions in the first year, a mark up of 57% on the procedural cost of angioplasty must be added to cover 1-year costs, while for bypass surgery this is only 1%. Nevertheless, the 1-year cost for angioplasty is still 36% less than for bypass surgery. As reinterventions after PTCA may stay considerably higher than for CABG for several years, the mark-up percentages will be substantially higher for longer time spans. This may tend to equalize the total costs of PTCA and CABG over time spans of perhaps 5-8 years. Sufficient data are not available to verify this statement. Clinicians must realize that choosing the most appropriate procedure is not only a matter of medical assessment but also a matter of cost effectiveness. CABG can be seen as an 'investment decision' while PTCA tends to become a decision with characteristics of 'maintenance planning'!

Angina Pectoris↗
PubMed1990

Enhanced morphological diagnosis in infective endocarditis by transoesophageal echocardiography.

Thirty three consecutive patients with clinically suspected endocarditis were studied by both precordial cross sectional echocardiography and transoesophageal echocardiography. The diagnostic value of both techniques was assessed. The data were compared with findings at operation in 25 patients. In 21 patients with native valve endocarditis precordial echocardiography showed evidence of vegetations in six patients and suggested their presence in nine. Transoesophageal echocardiography identified vegetations in 18 patients. Complications were seen in four patients at precordial echocardiography and in nine patients at transoesophageal echocardiography. Precordial echocardiography did not show vegetations in any of the 12 patients with prosthetic valve endocarditis whereas transoesophageal echocardiography showed vegetations in four. Complications were seen in four patients at precordial echocardiography and in 10 at transoesophageal echocardiography. Echocardiographic findings were confirmed at operation in all 25 operated patients. In two patients both echocardiographic techniques had missed the perforation of the cusps of the aortic valve that was seen at operation, but this had no effect on patient management. Transoesophageal echocardiography is the best diagnostic approach when infective endocarditis is suspected in patients with either native or prosthetic valves.

Adolescent↗
PubMed1990

Xanthine oxidoreductase activity in perfused hearts of various species, including humans.

Oxygen free radicals generated by xanthine oxidase have been implicated in cardiac damage. The activity of xanthine oxidase/reductase in adult rat heart is considerable. Its assay gives controversial results for other species, for example, rabbits and humans. Therefore, we perfused isolated hearts of various species, including explanted human hearts, to measure the conversion of exogenous hypoxanthine to xanthine and urate. We assayed these purines with high-performance liquid chromatography. The apparent xanthine oxidoreductase activities, calculated as release of xanthine plus 2x urate, were (milliunits per gram wet weight, mean +/- SEM) mice 33 +/- 3 (n = 5), rats 28.5 +/- 1.4 (n = 9), guinea pigs 14.4 +/- 1.0 (n = 5), rabbits 0.59 +/- 0.09 (n = 5), pigs less than 0.1 (n = 6), humans 0.31 +/- 0.04 (n = 7), and cows 3.7 +/- 0.8 (n = 4). In rabbit heart the conversion of hypoxanthine to xanthine was slow, and that of xanthine to urate was even slower. On the other hand, guinea pig and human heart released little xanthine, indicating that xanthine breakdown exceeds its formation. We conclude that isolated perfused mouse, rat, guinea pig, and also bovine hearts show considerable xanthine oxidoreductase activity, contrasting rabbit, porcine, and diseased human hearts.

Animals↗
PubMed1990

S35 and derived parameters during extracorporeal circulation together with hemodilution and hypothermia in humans.

A new concept in monitoring systemic oxygenation that includes the effect of changes in oxyhemoglobin dissociation curve (ODC) has been introduced. Using the S35 (saturation of hemoglobin at PO2 = 35 mmHg), real arterial available oxygen content (CavlO2) can be calculated being the maximum amount of oxygen that can be extracted from hemoglobin before oxygen diffusion into tissue becomes compromised and oxygen uptake (VO2) may decrease. The relation between VO2 and CavlO2 expressed by the extraction ratio of the arterial available oxygen content (ERav) gives a realistic indices of oxygen supply in relation to oxygen consumption. In the present study, during extracorporeal circulation (ECC), a severe shift to the left of the ODC could be observed. THe classic parameters for monitoring systemic oxygenation as mixed venous saturation (Sv-O2) and extraction ratio (ER) did not change. The S35 increased because of the shift to the left of the ODC with consequent decrease in CavlO2. The ERav reached critical values during ECC together with hemodilution and hypothermia. A severe decrease in mixed venous PO2 (Pv-O2) was also observed. The authors conclude that besides Pv-O2, the S35, the CavlO2 and especially the ERav are of value in monitoring the systemic oxygenation during hypothermic ECC.

Arteries↗
PubMed1990

The design, construction and clinical evaluation of a small phased array transducer for intraoperative echocardiography.

A small probe for cardiac surgery was developed and clinically tested. The probe is built as a phased array transducer with 64 elements with a centerfrequency of 5 MHz. The transducertip is connected with a handle by a flexible yet steerable shaft. This shaft has a length of 10 cm and can be set in a desired shape. Good quality images were obtained in all patients. The first study suggest many applications for a small probe in intraoperative echocardiography.

Cardiac Surgical Procedures↗
PubMed1990

Juxtaductal pulmonary artery coarctation. An underestimated cause of branch pulmonary artery stenosis in patients with pulmonary atresia or stenosis and a ventricular septal defect.

An angiographic and clinical study was performed to establish the prevalence of juxtaductal pulmonary artery coarctations in patients with pulmonary atresia or stenosis and a ventricular septal defect or a complex intracardiac defect. The present study is an adjunct to a previously reported portmortem study, in which the incidence of these pulmonary artery coarctations was found to be unexpectedly high. Pulmonary artery coarctations were identified angiographically in 10 of the 15 patients with pulmonary atresia. One additional patient had a bilateral ductus arteriosus and confluent pulmonary arteries, but did not have a pulmonary artery coarctation. Pulmonary artery coarctations were much less prevalent in the cases with pulmonary stenosis (5/50). However, these pulmonary artery coarctations appeared identical to those of the cases with pulmonary atresia. Fourteen pulmonary artery coarctations were located in the pulmonary artery at the side of the ductus arteriosus; this was left sided in 12 and right sided in two patients. In one patient the side of the ductus could not be established. The types and the locations of the pulmonary artery coarctations in the present study were identical to those in the previous postmortem study. Ductal tissue was found in many of the pulmonary artery coarctations of the postmortem study and is likely to be present in the clinical cases as well. The majority of the angiographically identified pulmonary artery coarctations were subsequently confirmed at operation or at autopsy. The clinical outcome and follow-up of the patients is discussed, and it is concluded that juxtaductal pulmonary artery coarctations should be specifically looked for before and during any type of surgical intervention in these patients.

Constriction, Pathologic↗
PubMed1989

Fracture of a balloon on a wire device during coronary angioplasty.

In a 61-year-old patient with unstable angina an attempt was made to dilate a severe stenosis in a tortuous obtuse marginal branch. The initial attempt with conventional equipment was not successful; although the wire could be advanced distal to the stenosis, a 2.0 balloon did not cross the stenosis. A second attempt with a balloon on a wire device resulted in fracture of this catheter, with the distal 2.8-cm-long fragment looped in the left coronary artery. Immediate bypass surgery was performed and the broken fragment was easily removed from the left coronary ostium. The patient made an uneventful recovery.

Angina Pectoris↗
PubMed1989

Probability of a return to work after either coronary balloon dilatation or coronary bypass surgery.

To examine whether coronary angioplasty has a different effect on work resumption than has coronary artery bypass surgery, we studied the work status of patients before and at least 1 year after either intervention. The population consisted of men aged less than 60 years, submitted to these procedures from September 1983 to July 1984. Of the 261 eligible patients, 219 (84%) participated, 94 after an angioplasty and 125 after a bypass procedure. 6 months preceding the intervention, 52% of the men were working. This had decreased to 47% at follow-up. Multiple logistic regression analysis showed that failure to resume work was correlated with bypass surgery vs balloon dilatation (rate ratio 1.8; 95% CI, 1.0-3.4), not working beforehand (rate ratio 6.5; 1.2-4.3), age greater than 55 years vs less than or equal to 50 years (rate ratio 2.6; 1.3-5.4) and with angina at follow-up (rate ratio 1.8; 1.0-3.3). Taking these additional risk factors into account permits a prediction of the probability of a return to work.

Angina Pectoris↗
PubMed1989

What is the ideal orientation of a mitral disc prosthesis? An in vivo haemodynamic study based on colour flow imaging and continuous wave Doppler.

Doppler colour flow imaging demonstrates normal laminar flow to enter the left ventricle in diastole through the mitral inflow tract located posteriorly in the left ventricle. Laminar flow then passes around the left ventricular apex to the anteriorly located outflow tract. As this is the normal physiologic flow pattern, it would seem appropriate that in the surgical implantation of a mitral tilting disc prosthesis the greater orifice should be directed posteriorly to mimic the normal native valve flow pattern. To determine whether variable positioning of the greater orifice had any significant haemodynamic consequences, intracavitary blood flow patterns were studied in 30 patients with mitral Björk-Shiley prostheses variously orientated in the mitral orifice. The orientation of the greater orifice (OGO) of the prosthesis was determined by fluoroscopy and the pattern of the left ventricular inflow from Doppler colour flow imaging. Twelve patients had their OGO and inflow directed towards the inflow tract (orientation I): nine patients had their OGO and inflow directed anteriorly towards the outflow tract (orientation II) and nine patients had their prosthesis with OGO and inflow in an intermediate position (orientation III). The mean prosthetic diastolic gradient, calculated using continuous wave Doppler, averaged 2.8 mmHg (+/- 0.5 mmHg) for the 25-mm prosthesis in orientation I, but 6.0 mmHg (+/- 0.7 mmHg) for the same size prosthesis in orientation II and 5.8 mmHg (+/- 0.9 mmHg) with a 25-mm prosthesis in orientation III. Similarly, for prostheses of 27 mm and 29-31 mm the lowest mean diastolic gradient was found in orientation I (2.7 mmHg +/- 0.8 and 2.8 mmHg +/- 0.5, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗