Use of the CYP2E1 genotype and phenotype for the biological monitoring of occupational exposure to styrene.

The CYP2E1 has been identified as the main cytochrome P450 isoform involved in human styrene metabolism. CYP2E1 presents polymorphism in humans and the different genotypes may, at least partly, be related to the different levels of individual expression of enzyme activity. We studied whether the genetic polymorphisms and phenotype of CYP2E1 modulate the level of urinary styrene metabolites and if they can be used for assessing risks of occupational exposure to styrene. A population of 49 male workers exposed to styrene (average level 362.7mg/m(3)) and a control group were selected. Samples of urine, blood and buccal swab were taken to determine the urinary biological indicators (phenylglyoxylic acid and mandelic acid), to quantify mRNA of CYP2E1 in blood using RT-PCR and to analyse different polymorphisms of enzyme CYP2E1 from buccal swab. We found decreased expression of mRNA of the enzyme, as well as decreased excretion of the styrene metabolites in individuals carrying the CYP2E1*5B heterozygote allele (cl/c2) with respect to the wild-type homozygote (c1/c1), which indicates a reduction in the inducibility of the enzyme in the presence of this polymorphism. The results show that the combined effect of both the CYP2E1 phenotype, measured by the expression of the specific mRNA in blood samples, and the CYP2E1*5B allele genotype, may explain the variability of urinary excretion of the styrene metabolites.

von Willebrand factor ristocetin cofactor (VWF:RCo) assay: implementation on an automated coagulometer (ACL).

BACKGROUND: VWF:RCo assay is the standard and widely used laboratory test for von Willebrand disease (VWD) diagnosis. It is hampered by high intra- and inter-assay imprecision and is time consuming. Automation may improve the assay performance and allow its routine application. OBJECTIVE: Automation of VWF:RCo on the ACL 7000 coagulometer (Instrumentation Laboratory, Milan, Italy) and its evaluation in VWD diagnosis. METHODS AND MATERIALS: Method performance determination: precision, detection limit (DL), interferences, dose-response curve. Method comparison: analysis of 105 plasma samples from normal subjects (50), VWD type 1 (24), VWD type 2 (24) and VWD type 3 (7) with ACL VWF:RCo and comparison with the reference aggregometric (AGM) method. RESULTS: ACL VWF:RCo: CVs around 10% vs. 19% of AGM method; DL: 0.08 U mL(-1); potential interferences from bilirubin, triglycerides and hemoglobin, avoided by suitable plasma dilution; high correlation with AGM VWF:RCo (Deming regression Y =-0.0277 + 1.0519X) either in normal or VWD plasmas. In VWD types 1 and 2, the VWF:RCo/VWF:Ag ratios are >0.6 or <0.6, respectively, when calculated with both AGM and ACL VWF:RCo values. CONCLUSIONS: The automated VWF:RCo on the ACL 7000 coagulometer shows precision improvement and high correlation with the reference AGM method. The test allows the diagnosis of both quantitative (VWD types 1 and 3) and qualitative (VWD type 2) forms of the disease. These results and the assay feasibility make it a suitable and reliable test for the routine diagnosis of VWD.

Muscular counterpulsation: preliminary results of a non-invasive alternative to intra-aortic balloon pump.

OBJECTIVES: IABP is the most widely used form of temporary cardiac assist and its benefits are well established. We designed an animal study to evaluate a device based on muscular counterpulsation (MCP) that should reproduce the same hemodynamic effects as IABP in a completely non-invasive way. METHODS: Six calves, 60+/-4 kg, divided into 2 groups, in general anaesthesia, equipped with EKG, Swan-Ganz, pressure probe in the femoral artery and flow probe in the left carotid artery, received either IABP through right femoral artery, or muscle counterpulsation (MCP). MCP consists of electrically induced skeletal muscle contraction during early diastole, triggered by EKG and microprocessor controlled by a portable device. For each animal the following parameters were also considered: mean aortic pressure (mAoP), CO, CI, left ventricular stroke work index (LVSWI), systemic vascular resistance (SVR) and mean femoral artery flow (Faf). We did 3 sets of measurements: baseline (BL), after 20 (M20) and 40 (M40) min of cardiac assistance. These measurements have been repeated after 40 min of rest for 3 times. Results are expressed as mean+/-SD. RESULTS: Baseline values: mAoP, 76.51+/-12 mmHg; mCVP, 11.5+/-3 mmHg; CO, 5+/-1 l/min per m(2); LVSWI, 0.77+/-0.2 KJ/m(2); SVR, 1040+/-15 dyns/cm(-5); Faf, 75.5+/-10 ml/min. IABP group: mAoP, 81.1+/-6 mmHg; mCVP, 1+/-0.1 mmHg; CO, 4.5+/-0.7 l/min per m(2); LVSWI, 0.69+/-0.2 KJ/m(2); SVR, 1424+/-8 dyns/cm(-5); Faf, 64.3+/-3 ml/min. MCP group: mAoP, 60.1+/-7 mmHg; mCVP, 23.6+/-2 mmHg; CO, 4.8+/-0.4 l/min per m(2); LVSWI, 0.69+/-0.2 KJ/m(2); SVR, 608+/-25 dyns/cm(-5); Faf, 92.3+/-12 ml/min. CONCLUSIONS: MCP and IABP had the same effects on CO and LVSWI. Moreover, MCP reduced SVR and increased the peripheral circulation without requiring any vascular access nor anticoagulation therapy.

Sutureless videoendoscopic thoracic aorta to iliac artery bypass: the easiest approach to occlusive aorto-iliac diseases.

OBJECTIVE: We designed an animal study to determine the feasibility of videoendoscopic thoracic aorta to iliac artery bypass using a sutureless anastomotic device for proximal anastomosis construction. METHODS: In 12 pigs the descending thoracic aorta was exposed using the thoracoscopic technique. A 4 mm PTFE thin wall graft was used as conduit. The proximal anastomosis was constructed using a mechanical device for sutureless anastomosis inserted through the camera port incision. The prosthesis was passed through the diaphragm in the retroperitoneal space and the distal anastomosis was done with running suture. RESULTS: The operation was successfully completed in 11 animals. One animal died due to hemorrage during anastomosis construction. Mean graft flow was 144 ml/min (range 88-167 mmHg). The angiogram showed no graft kinking or stenosis. Total operative time was 58 min (range 47-68 min). CONCLUSIONS: This approach allows quick and excellent exposure of the entire descending thoracic aorta. The use of the sutureless device to perform the proximal anastomosis dramatically reduces the technical demands of this procedure and could avoid an aortic clamp.

Cross-sectional compliance overestimates arterial compliance because it neglects the axial strain.

A high resolution echo-tracking system permits the calculation of cross-sectional compliance considering vessel diameter variations alone, and assumes that longitudinal movement of the vessel wall due to pulse pressure is negligible. However, using piezoelectric crystals sutured on the adventitia of the vessel wall we demonstrated that arterial length changes up to 5% (mean 2.7%) as a function of pulse pressure. Therefore, cross-sectional compliance seems to provide a limited approximation of the real phenomenon because it neglects axial vessel movement. Axial vessel movement is taken into account when the vessel compliance is calculated according to the principle of continuity of the mass: [equation: see text]. To verify this hypothesis we measured the blood flow gradient through 10 cm long segments of 10 pig carotid arteries (Qin - Qout) and divided it for the derivative of blood pressure over a given time (deltaP/deltat). For the same vessels, we calculated the cross-sectional compliance (CC) using the echo-tracking system (NIUS 02). We found a CC of (5.91 +/- 0.4) x 10(-7) micro m(2)/mm Hg and a segmental carotid compliance or dynamic compliance (C(d)) of (6.21 +/- 0.2) x 10(-8) micro m(3)/mm Hg. The impact of axial strain in calculations of compliance results in a dynamic compliance, which is one order of magnitude smaller than traditionally calculated arterial compliance.

[The heart transplant in Lausanne from 1987 to 2003]. / La greffe cardiaque à Lausanne de 1987 à 2003.

Since the availability of ciclosporine, the survival after heart transplantation has dramatically improved. We present our results since the beginning of our experience in 1987. We treated in the Lausanne University hospital, 150 patients for end-stage cardiac disease. Hundred and fifty-two transplantations were performed. The survival rate is comparable to the literature with 81% at one year, 70% at five year and 63 at ten year included the hospital mortality. We review the incidence of complications during the follow-up and report the modification in the management of these patients especially concerning the immunosuppression.

Surgery for aortic coarctation: a 30 years experience.

OBJECTIVE: A retrospective study to review the experience of a single center with surgery for aortic coarctation over a period of 30 years (1970-1999). METHODS: Criteria for inclusion: (a) aortic coarctation, isolated or associated with congenital heart defect; (b) surgery between 1970 and 1999. Data recorded: (1) date of surgery; (2) age at surgery; (3) associated lesions; (4) surgical technique; (5) simultaneous surgical procedures; (6) early and late surgical results in term of: (a) deaths; (b) need for reoperation because of re-coarctation or other cardiac lesion; (c) residual/recurrent pressure gradient, evaluated at cuff/Doppler at rest; (d) systemic hypertension, requiring medical treatment. RESULTS: One hundred and forty-one patients underwent surgery for aortic coarctation: 30 neonates, 29 infants, 45 children and 37 adults. Associated lesions were found in 8/37 (=21.6%) adults and in 73/104 (=70.1%) pediatric patients. There were no hospital deaths. During the follow-up there were one late death in the adults group (1/37=2.7%) and three late deaths in the pediatric group (3/104=2.9%), all unrelated with aortic coarctation. Re-operation because of re-coarctation occurred only in ten late survivors of the pediatric group (10/101=9.9%), 9/10 operated on before 1980 (P<0.00001). End-to-end anastomosis, enlarged to the aortic arch in neonates, was associated with the lowest incidence of re-coarctation (P<0.005). A significant (>20 mmHg at rest) pressure gradient was found in none of the adults, and in seven of the 91 pediatric patients (7/91=7.7%) late survivors. Three adults (3/36=8.3%) late survivors are on medical treatment to control systemic hypertension. CONCLUSIONS: The long-term results of our retrospective study confirm that surgery has to be considered the gold standard for the treatment of aortic coarctation. The interventional angioplasty techniques have to provide long-term outcome at least similar to the results obtained with surgery.

Preliminary clinical experience with the Heartflo anastomosis device.

UNLABELLED: A clinical, prospective trial to evaluate a multi-suture anastomotic device (Heartflo) is currently underway. This new surgical tool can be used during CABG to perform end-to-side or side-to-side coronary arteries anastomoses with interrupted suture technique. This reports our interim preliminary clinical experience. METHODS: From February to November 2000, we attempted 15 anastomoses with the multi-suture anastomotic device (Heartflo) in 11 patients with coronary artery disease. RESULTS: 7 males, 4 females, mean age 64 +/- 3 yrs received 15 anastomoses with the device. The target vessels were: 8 RCA, 3 LAD, 4 OM. Mean coronary diameter was 2 +/- 0.3 mm. Grafts used were 14 saphenous veins and 1 IMA. 13/15 anastomoses were completed with the device. 5/13 required 0 - 1 additional stitches versus 8/13 requiring more due to inappropriate tissue capture on the native coronary side. Average time was 17.7 +/- 2 min. In 2/15 cases, the procedure was converted to a traditional handsaw anastomosis. Postoperative CK movement without Q-wave in the EKG was observed in 1/11 patients. CONCLUSIONS: This device is a reliable instrument that provides reproducible coronary anastomoses with interrupted suture technique, although it also requires additional measures to improve tissue capture and process of handling sutures before extensive clinical application.

Alternatives to unfractionated heparin for anticoagulation in cardiopulmonary bypass.

Despite the progress made in the development of cardiopulmonary bypass (CPB) equipment, systemic anticoagulation with unfractionated heparin and post-bypass neutralization with protamine are still used in most perfusion procedures. However, there are a number of situations where unfractionated heparin, protamine or both cannot be used for various reasons. Intolerance of protamine can be addressed with extracorporeal heparin removal devices, perfusion with (no) low systemic heparinization and, to some degree, by perfusion with alternative anticoagulants. Various alternative anticoagulation regimens have been used in cases of intolerance to unfractionated heparin, including extreme hemodilution, low molecular weight heparins, danaparoid, ancrod, r-hirudin, abciximab, tirofiban, argatroban and others. In the presence of heparin-induced thrombocytopenia (HIT) and thrombosis, the use of r-hirudin appears to be an acceptable solution which has been well studied. The main issue with r-hirudin is the difficulty in monitoring its activity during CPB, despite the fact that ecarin coagulation time assessment is now available. A more recent approach is based on selective blockage of platelet aggregation by means of monoclonal antibodies directed to GPIIb/IIIa receptors (abciximab) or the use of a GPIIb/IIIa inhibitor (tirofiban). An 80% blockage of the GPIIb/IIIa receptors and suppression of platelet aggregation to less than 20% allows the giving of unfractionated heparin and running CPB in a standard fashion despite HIT and thrombosis. Likewise, at the end of the procedure, unfractionated heparin is neutralized with protamine as usual and donor platelets are transfused if necessary. GPIIb/IIIa inhibitors are frequently used in interventional cardiology and, therefore, are available in most hospitals.

Treatment of congenital aortic valve stenosis: impact of the Ross operation.

GOAL: To evaluate the impact of the Ross operation, recently (1997) introduced in our unit, for the treatment of patients with congenital aortic valve stenosis. METHODS: The period from January 1997 to December 2000 was compared with the previous 5 years (1992-96). Thirty-seven children (< 16 yrs) and 49 young adults (16-50 yrs) with congenital aortic valve stenosis underwent one of these treatments: percutaneous balloon dilatation (PBD), aortic valve commissurotomy, aortic valve replacement and the Ross operation. The Ross operation was performed in 16 patients, mean age 24.5 yrs (range 9-46 yrs) with a bicuspid stenotic aortic valve, 7/10 adults with calcifications, 2/10 adults with previous aortic valve commissurotomy, 4/6 children with aortic regurgitation following PBD, and 1/6 children who had had a previous aortic valve replacement with a prosthetic valve and aortic root enlargement. RESULTS: PBD was followed by death in two neonates (fibroelastosis); all other children survived PBD. Although there were no deaths, PBD in adults was recently abandoned, owing to unfavourable results. Aortic valve commissurotomy showed good results in children (no deaths). Aortic valve replacement, although associated with good results (no deaths), has been recently abandoned in children in favour of the Ross operation. Over a mean follow-up of 16 months (2-40 months) all patients are asymptomatic following Ross operation, with no echocardiographic evidence of aortic valve regurgitation in 10/16 patients and with trivial regurgitation in 6/16 patients. CONCLUSIONS: The approach now for children and young adults with congenital aortic valve stenosis should be as follows: (1) PBD is the first choice in neonates and infants; (2) Aortic valve commissurotomy is the first choice for children, neonates and infants after failed PBD; (3) The Ross operation is increasingly used in children after failed PBD and in young adults, even with a calcified aortic valve.

Animal model to compare the effects of suture technique on cross-sectional compliance on end-to-side anastomoses.

OBJECTIVE: An animal model has been developed to compare the effects of suture technique on the luminal dimensions and compliance of end-to-side vascular anastomoses. METHODS: Carotid and internal mammalian arteries (IMAs) were exposed in three pigs (90 kg). IMAs were sectioned distally to perform end-to-side anastomoses on carotid arteries. One anastomosis was performed with 7/0 polypropylene running suture. The other was performed with the automated suture delivery device (Perclose/Abbott Labs Inc.) that makes a 7/0 polypropylene interrupted suture. Four piezoelectric crystals were sutured on toe, heel and both lateral sides of each anastomosis to measure anastomotic axes. Anastomotic cross-sectional area (CSAA) was calculated with: CSAA = pi x mM/4 where m and M are the minor and major axes of the elliptical anastomosis. Cross-sectional anastomotic compliance (CSAC) was calculated as CSAC=Delta CSAA/Delta P where Delta P is the mean pulse pressure and Delta CSAA is the mean CSAA during cardiac cycle. RESULTS: We collected a total of 1200000 pressure-length data per animal. For running suture we had a mean systolic CSAA of 26.94+/-0.4 mm(2) and a mean CSAA in diastole of 26.30+/-0.5 mm(2) (mean Delta CSAA was 0.64 mm(2)). CSAC for running suture was 4.5 x 10(-6)m(2)/kPa. For interrupted suture we had a mean CSAA in systole of 21.98+/-0.2 mm(2) and a mean CSAA in diastole of 17.38+/-0.3 mm(2) (mean Delta CSAA was 4.6+/-0.1 mm(2)). CSAC for interrupted suture was 11 x 10(-6) m(2)/kPa. CONCLUSIONS: This model, even with some limitations, can be a reliable source of information improving the outcome of vascular anastomoses. The study demonstrates that suture technique has a substantial effect on cross-sectional anastomotic compliance of end-to-side anastomoses. Interrupted suture may maximise the anastomotic lumen and provides a considerably higher CSAC than continuous suture, that reduces flow turbulence, shear stress and intimal hyperplasia. The Heartflo anastomosis device is a reliable instrument that facilitates performance of interrupted suture anastomoses.

Transposition of great arteries and single coronary artery: a new surgical technique for the arterial switch operation.

A single coronary artery can complicate the surgical technique of arterial switch operations, impairing early and late outcomes. We propose a new surgical approach, successfully applied in a 2.1 kg neonate, aimed at reducing the risk of early and late compression and/or distortion of the newly constructed coronary artery system.

Tolerance of isolated rat hearts to low-flow ischemia and hypoxia of increasing duration: protective role of down-regulation and ATP during ischemia.

We tested the hypothesis that down-regulated hearts, as observed during low-flow ischemia, adapt better to low O2 supply than non-down-regulated, or hypoxic, hearts. To address the link between down-regulation and endogenous ischemic protection, we compared myocardial tolerance to ischemia and hypoxia of increasing duration. To that end, we exposed buffer-perfused rat hearts to either low-flow ischemia or hypoxia (same O2 shortage) for 20, 40 or 60 min (n = 8/group), followed by reperfusion or reoxygenation (20 min, full O2 supply). At the end of the O2 shortage, the rate-pressure product was less in ischemic than hypoxic hearts (p < 0.0001). The recovery of the rate-pressure product after reperfusion or reoxygenation was not different for t = 20 min, but was better in ischemic than hypoxic hearts for t = 40 and 60 min (p < 0.02 and p < 0.0002, respectively). The end-diastolic pressure remained unchanged during low-flow ischemia (0.024 +/- 0.013 mmHg x min(-1)), but increased significantly during hypoxia (0.334 +/- 0.079 mmHg x min(-1)). We conclude that, while the duration of hypoxia progressively impaired the rate-pressure product and the end-diastolic pressure, hearts were insensitive of the duration of low-flow ischemia, thereby providing evidence that myocardial down-regulation protects hearts from injury. Excessive ATP catabolism during ischemia in non-down-regulated hearts impaired myocardial recovery regardless of vascular, blood-related and neuro-hormonal factors. These observations support the view that protection is mediated by the maintenance of the ATP pool.