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Biomedical subjects

P G Jansen

Publications and source records attributed to P G Jansen.

At least 19 recordsLinked to original sources
PubMed2001

Mechanical circulatory support for advanced heart failure: effect of patient selection on outcome.

BACKGROUND: Use of wearable left ventricular assist systems (LVAS) in the treatment of advanced heart failure has steadily increased since 1993, when these devices became generally available in Europe. The aim of this study was to identify in an unselected cohort of LVAS recipients those aspects of patient selection that have an impact on postimplant survival. METHODS AND RESULTS: Data were obtained from the Novacor European Registry. Between 1993 and 1999, 464 patients were implanted with the Novacor LVAS. The majority had idiopathic (60%) or ischemic (27%) cardiomyopathy; the median age at implant was 49 (16 to 75) years. The median support time was 100 days (4.1 years maximum). Forty-nine percent of the recipients were discharged from the hospital on LVAS; they spent 75% of their time out of the hospital. For a subset of 366 recipients, for whom a complete set of data was available, multivariate analysis revealed that the following preimplant conditions were independent risk factors for survival after LVAS implantation: respiratory failure associated with septicemia (odds ratio 11.2), right heart failure (odds ratio 3.2), age >65 years (odds ratio 3.01), acute postcardiotomy (odds ratio 1.8), and acute infarction (odds ratio 1.7). For patients without any of these factors, the 1-year survival after LVAS implantation including the posttransplantation period was 60%; for the combined group with at least 1 risk factor, it was 24%. CONCLUSIONS: Careful selection, specifically implantation before patients become moribund, and improvement of management may result in improved outcomes of LVAS treatment for advanced heart failure.

Adolescent↗
PubMed2001

Improved outcomes with an implantable left ventricular assist system: a multicenter study.

BACKGROUND: Cumulative experience with the Novacor wearable electric left ventricular assist system (LVAS) now exceeds 850 recipients. The pump inflow conduit (IFC) has been implicated in embolic complications. METHODS: Clinical outcomes were compared for two IFC designs in a retrospective, nonrandomized, multicenter study. The original IFC (woven, unsupported, crimped polyester: control group) and an alternative IFC (knitted, gelatin-sealed, integrally supported, uncrimped polyester: test group) were utilized upon availability in North American and European centers. Differences in cerebral embolism to 180 days postimplant were analyzed. RESULTS: Four hundred ninety patients implanted between August 1996 and August 1999, were studied. Two hundred eighty-eight received the control IFC and 202 received the test IFC. The groups (control, test) were well matched for age (48, 49 years), etiology (idiopathic 53%[152 of 288], 55% [112 of 202]; ischemic 34% [97 of 288], 33% [66 of 202]) and mean observation time (97, 91 days). The incidence of embolic cerebrovascular accidents (CVA) was 21% (60 of 288) in the control and 12% (24 of 202) in the test group (p = 0.010). Independent risk factors for embolic CVA were found to be preimplant acute myocardial infarction (odds ratio 4.3), age above 50 years (odds ratio 2.1), and ischemic etiology (odds ratio 1.7). There was no difference in survival between the groups (71% [205 of 288], 68% [137 of 202]). CONCLUSIONS: The alternative (test) IFC has significantly reduced the incidence of embolic CVA. This improvement is likely due to increased resistance to deformation at implant, improved neointimal adhesion, and more favorable blood flow characteristics within the conduit.

Cardiomyopathies↗
PubMed2001

The dynamics of assessment center validity: results of a 7-year study.

The authors investigated temporal trends in the validity of an assessment center consisting of a group discussion and an analysis presentation exercise for predicting career advancement as measured by average salary growth over a 7-year period in a sample of 679 academic graduates. The validity of the overall assessment rating for persons with tenure of 7 years, corrected for initial differences in starting salaries and restriction in range, was .39. There was a considerable time variation in the validity of both the overall assessment rating and the assessment center dimensions. In accordance with findings from research in managerial effectiveness and development, the interpersonal effectiveness dimension became valid only after a number of years, whereas the firmness dimension was predictive in the whole period and increased with time. For comparison, validity trends for 2 types of interviews and a mental test were also studied.

Adult↗
PubMed2000

Long-term mechanical circulatory support with the wearable Novacor left ventricular assist system.

OBJECTIVE: As of July 1st 1999, 36 European patients have lived for more than 1 year supported by the Novacor wearable electric left ventricular assist system (LVAS). All were unresponsive to maximum medical therapy, prior to implantation. These patients offer an unique opportunity to evaluate the feasibility of long-term ambulatory mechanical circulatory support as a therapeutic option for patients in profound cardiac failure. METHODS: Data was obtained from the Novacor European Registry. RESULTS: At the time of implantation, median age was 55 (18-67) years. Aetiology was ischemic (9, 25%) or idiopathic (26, 72%) cardiomyopathy, and myocarditis (1, 3%). Median duration of LVAS support was 1.49 (1. 03-4.10) years. Eight recipients had LVAS support times >2 years, of which two were >3 years and one >4 years. The median time spent outside the hospital was 1.27 (0.58-3.83) years, representing 82% of the duration of LVAS support. No mechanical failure was observed during the entire observation period. One pump was replaced electively after 3.67 years due to pump driver wear-out. Twelve patients (33%) are currently on support while 17 were transplanted (14, 39%) or weaned (3, 8%). Seven (19%) patients died after a median of 1.24 years circulatory support. CONCLUSIONS: Experience with long-term Novacor LVAS recipients has demonstrated effective rehabilitation in this group of patients with refractory advanced heart failure. This suggests that LVAS therapy may offer a safe and realistic option for patients for whom no other effective therapy is available. The patient sub-population that would benefit most from this therapy remains to be defined.

Adolescent↗
PubMed1999

Inflammatory response to cardiopulmonary bypass using roller or centrifugal pumps.

BACKGROUND: The inflammatory response in 29 patients undergoing coronary artery bypass grafting using either roller or centrifugal (CFP) pumps was evaluated in a prospective study. METHODS: Patients were randomized in roller pump (n = 15) and CFP (n = 14) groups. Terminal complement complex activation (SC5b-9) and neutrophil activation (elastase) were assessed during the operation. Cytokine production (tumor necrosis factor-alpha, interleukin-6, interleukin-8) and circulating adhesion molecules (soluble endothelial-leukocyte adhesion molecule-1 and intercellular adhesion molecule-1) were assessed after the operation. RESULTS: Release of SC5b-9 after stopping cardiopulmonary bypass and after protamine administration was higher in the CFP group (p = 0.01 and p = 0.004). Elastase level was higher after stopping cardiopulmonary bypass using CFP (p = 0.006). Multivariate analysis confirmed differences between roller pump and CFP groups in complement and neutrophil activation. After the operation, a significant production of cytokines was detected similarly in both groups, with peak values observed within the range of 4 to 6 hours after starting cardiopulmonary bypass. However, interleukin-8 levels were higher using CFP 2 hours after starting cardiopulmonary bypass (p = 0.02). Plasma levels of adhesion molecules were similar in both groups within the investigation period. CONCLUSIONS: During the operation, CFP caused greater complement and neutrophil activation. After the operation, the inflammatory response was similar using either roller pump or CFP.

Cardiopulmonary Bypass↗
PubMed1998

Inflammatory response to cardiopulmonary bypass using two different types of heparin-coated extracorporeal circuits.

Previous reports have highlighted the disparity in biocompatibility of two differently engineered heparin coatings during the cardiopulmonary bypass (CPB) procedure. The aim of this prospective study was to evaluate the impact of the difference in haemocompatibility provided by either the Duraflo II equipment or the Carmeda equipment in the terminal inflammatory response observed after coronary artery surgery. Thirty patients were randomly allocated to two groups to be operated on using either Duraflo II equipment (group I) or Carmeda equipment (group 2) for extracorporeal circulation (ECC). Initial inflammatory response was assessed by terminal complement complex activation (SC5b-9). The late inflammatory response observed in the postoperative period was assessed by measuring cytokine production (tumour factor necrosis (TNF alpha), interleukin IL-6, interleukin IL-8) and circulating concentrations of adhesion molecules (ELAM-1, ICAM-1). The release of SC5b-9 after CPB and after protamine administration was lower in group 2 than in group 1 (p = 0.0002 and p = 0.006, respectively). A significant production of cytokines was detected in both groups with peak values observed within the time range of 4-6 h after the start of CPB.

Aged↗
PubMed1997

Cell-derived microparticles generated in patients during cardiopulmonary bypass are highly procoagulant.

BACKGROUND: Microparticles from platelets and other cells have been extensively studied and characterized in vitro. Although the level of platelet-derived microparticles is elevated in a variety of diseases, including cardiac surgery, virtually nothing is known about their functions in vivo. The aim of the present study was to investigate the procoagulant properties of microparticles generated in vivo. METHODS AND RESULTS: In 6 patients at the end of cardiopulmonary bypass, 14.8 x 10(9)/L (median; range, 9.7 to 27.4 x 10(9)/L) platelet-derived microparticles were present in pericardial blood, whereas blood obtained from the systemic circulation contained 1.6 x 10(9)/L (median; range, 0.4 to 8.9 x 10(9)/L) of such microparticles, as determined by flow cytometry. Microparticles stained positively for phosphatidylserine as determined with labeled annexin V. In contrast to systemic blood, pericardial blood contained not only microparticles of platelet origin but also microparticles that originated from erythrocytes, monocytes, or granulocytes, and other hitherto unknown cellular sources. Plasma prepared from pericardial blood and to a lesser extent plasma from systemic blood obtained at the same time, stimulated formation of thrombin in vitro. This activity of pericardial plasma was lost after removal of its microparticles by high-speed centrifugation, whereas the corresponding microparticle pellet was strongly procoagulant. The generation of thrombin in vitro involved a tissue factor/factor VII-dependent and factor XII-independent pathway. CONCLUSIONS: This study is the first to demonstrate that microparticles generated in vivo can stimulate coagulation.

Annexin A5↗
PubMed1997

Activation of the complement system during and after cardiopulmonary bypass surgery: postsurgery activation involves C-reactive protein and is associated with postoperative arrhythmia.

BACKGROUND: Complement activation during cardiopulmonary bypass (CPB) surgery is considered to result from interaction of blood with the extracorporeal circuit. We investigated whether additional mechanisms may contribute to complement activation during and after CPB and, in particular, focused on a possible role of the acute-phase protein C-reactive protein (CRP). METHODS AND RESULTS: In 19 patients enrolled for myocardial revascularization, perioperative and postoperative levels of complement activation products, interleukin-6 (IL-6), CRP, and complement-CRP complexes, reflecting CRP-mediated complement activation in vivo, were measured and related to clinical symptoms. A biphasic activation of complement was observed. The ratio between the areas under the curve of perioperative and postoperative C3b/c and C4b/c were 3:2 and 1:46, respectively. IL-6 levels reached a maximum at 6 hours post-surgery. CRP levels peaked on the second postoperative day. Each complement-CRP complex had peak levels on the second or third postoperative day. By multivariate analysis, maximum levels of CRP on the second postoperative day were mainly explained by C4b/c levels after protamine administration, leukocyte count on the second postoperative day, and preoperative levels of CRP. Peak levels of C4b/c after protamine administration (P=.0073) and on the second postoperative day correlated with the occurrence of arrhythmia on the same day (P=.0065). CONCLUSIONS: Cardiac surgery with CPB causes a biphasic complement activation. The first phase occurs during CPB and results from the interaction of blood with the extracorporeal circuit. The second phase, which occurs during the first 5 days after surgery, involves CRP, is related to baseline CRP levels, and is associated with clinical symptoms such as arrhythmia.

Acute-Phase Reaction↗
PubMed1997

Heparin coating with aprotinin reduces blood activation during coronary artery operations.

BACKGROUND: This study was performed to evaluate whether the combination of heparin-coated extracorporeal circuits (ECC) and aprotinin treatment reduce blood activation during coronary artery operations. METHODS: Sixty patients were prospectively divided into two groups (heparin-coated ECC and uncoated ECC groups), which were comparable in terms of age, sex, left ventricular function, preoperative aspirin use and consequent intraoperative aprotinin use, number of grafts, duration of aortic cross-clamping, and duration of cardiopulmonary bypass. Blood activation was assessed at different times during cardiopulmonary bypass by determination of complement activation (C3 and C4 activation products C3b/c and C4b/c and terminal complement complex), leukocyte activation (elastase), coagulation (scission peptide fibrinopeptide 1 + 2), and fibrinolysis (D-dimers). RESULTS: Univariate analysis showed that heparin-coated ECC, under conditions of standard heparinization, did not reduce perioperative blood loss and need for transfusion. Heparin coating, however, reduced maximum values of C3b/c (446 +/- 212 nmol/L versus 632 +/- 264 nmol/L with uncoated ECC; p = 0.0037) and maximum C4b/c values (92 +/- 48 nmol/L versus 172 +/- 148 nmol/L with uncoated ECC; p = 0.0069). Levels of terminal complement complex, elastase, fibrinopeptide 1 + 2, and D-dimers were not significantly modified by the use of heparin-coated ECC. Multivariate analysis showed that the intergroup differences in maximum C3b/c and C4b/c values were more pronounced in women in part with high baseline values of C3b/c. We also found that aprotinin contributed to the reduction of maximum values of fibrinopeptide 1 + 2 and D-dimers, whereas heparin coating had no significant influence on these parameters. CONCLUSIONS: We found no evidence of combined properties of heparin-coated ECC and aprotinin in reducing complement activation, coagulation, and fibrinolysis. We therefore recommend use of both together to achieve maximal reduction of blood activation during cardiopulmonary bypass for coronary artery operations.

Aprotinin↗
PubMed1997

Heparin coating of extracorporeal circuits inhibits contact activation during cardiac operations.

OBJECTIVE: Heparin coating reduces complement activation on the surface of extracorporeal circuits. In this study we investigated its effect on activation of the contact system in 30 patients undergoing coronary artery bypass grafting with the use of a heparin-coated (Duraflo II, Baxter Healthcare Corp., Edwards Division, Santa Ana, Calif.; n = 15) or an uncoated extracorporeal circuit (n = 15). METHODS: Plasma markers that reflect activation of contact (kallikrein-C1-inhibitor complexes), coagulation (prothrombin fragments F1 + 2), or fibrinolytic (plasmin-alpha 2-antiplasmin complexes) systems were determined before and during the operation. The generation of kallikrein-C1-inhibitor complexes was reduced by 62% (p = 0.06) after the onset of cardiopulmonary bypass and by 43% (p = 0.026) after the cessation of bypass in the group in which a heparin-coated circuit was used compared with the group in which the circuit was uncoated. Generation was reduced by 58% (p = 0.06) when the ratio of kallikrein-C1-inhibitor to prekallikrein after onset of bypass was considered. We detected significant increases in F1 + 2 levels in both groups and increases in plasmin-alpha 2-antiplasmin complexes in the heparin-coated group at cessation of bypass, but no intergroup differences were observed. Thus use of heparin-coated extracorporeal circuits during cardiac operations reduces formation of kallikrein-C1-inhibitor complexes when compared with use of uncoated circuits. The heparin coating is not accompanied by similar reductions in coagulation or fibrinolysis, suggesting that thrombin and plasmin formation during cardiopulmonary bypass occurs mainly independently of the contact system activation.

Aged↗
PubMed1997

Clinical evaluation of Duraflo II heparin treated extracorporeal circulation circuits (2nd version). The European Working Group on heparin coated extracorporeal circulation circuits.

OBJECTIVES: To evaluate whether the application of heparin treated circuits for elective coronary artery surgery improves postoperative recovery, a European multicenter randomised clinical trial was carried out. METHODS: In 11 European heart centers, 805 low-risk patients underwent cardiopulmonary bypass (CPB) with either an untreated circuit (n = 407) or an identical but heparin treated circuit (n = 398, Duraflo II). RESULTS: Significant differences were found among participating centers with respect to patient characteristics, blood handling procedures and postoperative care. The use of heparin treated circuits revealed no overall changes in blood loss, blood use, time on ventilator, occurrence of adverse events, morbidity, mortality, and intensive care stay. These results did not change after adjustment for centers and (other) prognostic factors as analysed with logistic regression. In both groups no clinical or technical (patient or device related) side effects were reported. Because female gender and aortic cross clamp time appeared as prognostic factors in the logistic regression analysis, a subgroup analysis with these variables was performed. In a subpopulation of females (n = 99), those receiving heparin treated circuits needed less blood products, had a lower incidence of rhythm disturbances and were extubated earlier than controls. In another subgroup of patients with aortic cross clamp time exceeding 60 min (n = 197), the amount of patients requiring prolonged intensive care treatment (> 24 h) was significantly lower when they received heparin treated circuits versus controls. CONCLUSION: These findings suggest that improved recovery can be expected with heparin treated circuits in specific higher risk patient populations (e.g. females) and when prolonged aortic cross clamp time is anticipated. Further investigations are recommended to analyses the clinical benefit of heparin treated circuits in studies with patients in different well defined risk categories and under better standardised circumstances.

Adult↗
PubMed1997

Biocompatibility of three different membrane oxygenators: effects on complement, neutrophil and monocyte activation.

The inflammatory reaction of extracorporeal circuits can be assessed by measuring complement activation and the release of activation markers of leucocytes. The purpose of this study was to compare three commercially available membrane oxygenators with respect to complement (C3a), granulocyte (lactoferrin) and monocyte (interleukin-6, IL-6) activation. Thirty patients undergoing cardiac surgery were randomly assigned to undergo cardiopulmonary bypass (CPB) with one of the following oxygenators: a polypropylene hollow-fibre membrane (group 1; 2.2 m2), a polypropylene flat-sheet membrane (group 2; 3.1 m2) or a silicone envelope membrane (group 3, 3.5 m2). In all patients, a significant increase in C3a in plasma occurred during CPB with peak levels after the administration of protamine sulphate. In blood samples taken before aortic crossclamp release, at the end of CPB, and 20 min after protamine administration C3a was significantly lower in group 1 than in the other two groups. Lactoferrin increased significantly during CPB in all patients without a significant difference between the groups. IL-6 did not increase during CPB, but raised significantly after 4 h in the intensive care unit in all groups. Moreover, IL-6 was significant lower in group 1 than group 3. The data suggest that the polypropylene hollow-fibre membrane oxygenator, i.e. the oxygenator with the smallest surface area, is more biocompatible than the other types, probably because of a smaller contact surface area.

Biocompatible Materials↗
PubMed1997

[Effects of functional differentiation within home care on the quality of care--from the client's viewpoint].

In home care nursing work is redesigned by differentiated practice (= skill mix) and specialization. The aim of this redesign is efficient use of staff, and maintenance or improvement of quality of care. In this article the effects of differentiated practice and specialization are studied in respect of quality of care. The perspective of the client was taken as the starting point. Quality of care was defined as the discrepancy between clients' expectations and perceptions of several aspects of care. The effects of work redesign were determined on the basis of a comparison between an experimental (n = 103) and a control group (n = 108). Data-analysis showed hardly any differences. Possible explanations are the premature status of the projects and the fact that clients are usually (very) satisfied. The margin in which differences between the experimental and the control group should occur is therefore very small. However, by means of this approach a detailed picture can be obtained of the subjective standard clients use to judge the quality of care.

Aged↗
PubMed1996

Increased oxygen consumption after cardiac surgery is associated with the inflammatory response to endotoxemia.

OBJECTIVE: The aim of this study was to determine whether the increase in post-operative oxygen consumption (delta VO2) in cardiac surgery patients is related to endotoxemia and subsequent cytokine release and whether delta VO2 can be used as a parameter of post-perfusion syndrome. DESIGN: Prospective study. SETTING: Operating room and intensive care unit of a university hospital. PATIENTS: Twenty-one consecutive male patients undergoing elective coronary artery bypass surgery without major organ dysfunction and not receiving corticosteroids. MEASUREMENTS AND RESULTS: Plasma levels of endotoxin, tumor necrosis factor (TNF) and interleukin-6 (IL-6) were measured before, during and for 18 h after cardiac surgery. Oxygen consumption, haemodynamics, the use of IV fluids and dopamine, body temperature and the time of extubation were also measured. Measurements from patients with high delta VO2 (> or = median value of the entire group) were compared with measurements from patients with low delta VO2 (< median). Patients with high delta VO2 had higher levels of circulating endotoxin (P = 0.004), TNF (P = 0.04) and IL-6 (P = 0.009) received more IV fluids and dopamine while in the ICU, and were extubated later than patients with low delta VO2. Several hours after delta VO2 the patient's body temperature rose. Forward stepwise regression analysis showed that circulating endotoxin and TNF explained 50% of the variability of delta VO2. CONCLUSIONS: This study demonstrates that patients with high post operative oxygen consumption after elective cardiac surgery have higher circulating levels of endotoxin, TNF and IL-6 and also have more symptoms of post-perfusion syndrome. Early detection of high VO2 might be used as a clinical signal to improve circulation in order to meet the high oxygen demand of inflammation. In addition, continuous measurement of VO2 provides us with a clinical parameter of inflammation in interventional studies aiming at a reduction of endotoxemia or circulating cytokines.

Adult↗
PubMed1996

Circulating endothelin in cardiac operations: influence of blood pressure and endotoxin.

BACKGROUND: Endothelin is involved in the control of cardiovascular and renal functions and acts as a neuromodulator. METHODS: In a prospective study among 15 male patients who underwent coronary artery bypass grafting, we investigated the release pattern and possible stimuli of circulating endothelin. RESULTS: We detected a steep increase in endothelin concentrations after the onset of cardiopulmonary bypass (CPB), and a second minor increase during CPB. The steep increase in endothelin concentrations correlated with the change in arterial pressures at the onset of CPB (r = -0.57; p < 0.03). The slow increase in endothelin concentrations during CPB, however, correlated with mean endotoxin levels during and after CPB (r = 0.60; p < 0.02). CONCLUSIONS: The change in arterial pressure at the onset of CPB seems to induce a steep and fast increase in circulating endothelin level, which is probably mediated through the baroreceptors. The slow increase in endothelin level during CPB is associated with increased circulating endotoxin concentration. It may be that either endothelin-mediated vasoconstriction induces endotoxin transmigration from the intestine or endotoxin stimulates secretion from endothelial cells.

Aged↗