Biomedical subjects

S Martens

Publications and source records attributed to S Martens.

At least 19 recordsLinked to original sources

PubMed2006

Decalcification of the mitral annulus: surgical experience in 81 patients.

OBJECTIVE: Mitral valve surgery in the presence of extensive calcification of the mitral annulus is a technical challenge and increases perioperative risk. This study reviews our experience with decalcification of the mitral annulus in patients undergoing mitral valve reconstruction or replacement. METHODS: From 1995 to 2003, 81 patients (mean age 64 +/- 13 years, 30 male, 51 female) with extensive calcification of the mitral annulus underwent mitral valve repair (n = 42) or replacement (biological n = 20, mechanical n = 19). The mean follow-up was 24 months. Patients presented with a mean EuroSCORE of 7. Concomitant surgical procedures were performed in 62 %. Patient outcomes were retrospectively assessed. RESULTS: Perioperative survival was 97.5 % (n = 79) and hospital survival was 91.3 % (n = 74). Two-year survival was 88.9 %. Eight patients needed reexploration due to bleeding and five patients required prolonged mechanical ventilation. No perioperative stroke was observed. Freedom from reoperation was 90.2 % (n = 73). Early reoperation for recurrent incompetence was necessary in 3 patients and late reoperation in 5 patients. CONCLUSIONS: Despite the elevated perioperative risk and the high risk of reoperation with this procedure, decalcification of the annulus and repair/replacement of the mitral valve could be performed with good clinical results.

Adolescent↗

PubMed2006

Computed tomographic changes of the brain and clinical outcome of patients with seizures and epilepsy after an ischaemic hemispheric stroke.

It is not well established whether seizures and epilepsy after an ischaemic stroke increase the disability of patients. Seventy-two patients with delayed seizures after a hemispheric infarct (37 with a single seizure and 35 with epilepsy) were included in the study. The modified Rankin scale was used to compare disability of the patients at 1 month after stroke and at 2 weeks after single or the last seizure, in case of epilepsy. The size of the X-ray hypoattenuation zone was compared on computed tomographic (CT) scans, performed in the weeks after the stroke and 1 week after single or repeated seizures. Lesion size was determined by superimposing the CT slices on digital cerebral vascular maps, on which the contours of the infarct area were delineated. The extent of the infarcts was expressed as the percentage fraction of the total surface area of the cerebral hemisphere. Groups with a single seizure and with epilepsy were mutually compared. Infarcts predominated in the parieto-temporal cortical regions. In the overall group the median Rankin score worsened significantly after seizures. The average size of the X-ray hypoattenuation zone was also significantly increased on the CT scans after the seizures, compared with those after stroke, without clear evidence of recent infarction. Mutual comparison of patients with a single seizure episode and of those with epilepsy showed only a trend of more severe disability and of increase in lesion size in the post-stroke epilepsy group. Delayed seizures and epilepsy after ischaemic stroke are accompanied by an increase in lesion size on CT and by worsening of the disability of the patients. This study does not allow to determine whether this is due to stroke recurrence or due to additional damage as a result of the seizures themselves.

Aged↗

PubMed2006

Behavior of gaseous microemboli in extracorporeal circuits: air versus CO2.

BACKGROUND: Open heart surgery is associated with serious risk of cerebral and peripheral organ dysfunction, attributed in part to air microbubbles generated in or not eliminated from the extracorporeal circuit (ECC). Venous air leakage leads to increased arterial bubble load. CO2 replacing air in cardiac chambers show faster resorption times, reducing possible cerebral or peripheral organ damage after heart valve interventions. In two models of ECC the effect of air entering closed circuits was demonstrated and compared to the effect of CO2 entry. METHODS: Fragmentation and dissolution of gas (0.5 mL) was evaluated in an in vitro model of ECC, using ultrasonic bubble detection. Air leakage (10 mL) in the venous line of the ECC was simulated and compared to the effect of the same quantity of CO2 entering the circuit. Both models used whole blood priming and physiological conditions, verified with blood gas analyses. RESULTS: Fragmentation and dissolution of gas bubbles injected into a closed ECC could be demonstrated, complete resorption of CO2 bubbles was observed earlier than complete resorption of room air (5.0+/-0.6 vs. 14.4+/-5.9 min, p=0.0009). CO2 entering the venous line lead to 40% less arterial bubble load as compared to the same amount of room air entering the circuit (2099+/-991 vs. 3555+/-632, p=0.005). CONCLUSIONS: Current ECC systems fail to eliminate gas entering the circuit, leading rather to microbubble dispersion. CO2 is much faster resorbed within the circuit than room air. In open heart surgery as valvular operations, CO2 insufflation into the operative field is protective, as we have demonstrated in our models.

Air↗

PubMed2005

Correlation of EEG spectral entropy with regional cerebral blood flow during sevoflurane and propofol anaesthesia.

ENTROPY index monitoring, based on spectral entropy of the electroencephalogram, is a promising new method to measure the depth of anaesthesia. We examined the association between spectral entropy and regional cerebral blood flow in healthy subjects anaesthetised with 2%, 3% and 4% end-expiratory concentrations of sevoflurane and 7.6, 12.5 and 19.0 microg.ml(-1) plasma drug concentrations of propofol. Spectral entropy from the frequency band 0.8-32 Hz was calculated and cerebral blood flow assessed using positron emission tomography and [(15)O]-labelled water at baseline and at each anaesthesia level. Both drugs induced significant reductions in spectral entropy and cortical and global cerebral blood flow. Midfrontal-central spectral entropy was associated with individual frontal and whole brain blood flow values across all conditions, suggesting that this novel measure of anaesthetic depth can depict global changes in neuronal activity induced by the drugs. The cortical areas of the most significant associations were remarkably similar for both drugs.

Adult↗

PubMed2004

Flavonoid biosynthesis in the tea plant Camellia sinensis: properties of enzymes of the prominent epicatechin and catechin pathways.

Leaves of tea (Camellia sinensis L.) contain extraordinary large amounts of (-)-epigallocatechin, (-)-epicatechin, (+)-gallocatechin, and (+)-catechin and derivatives of these compounds that show positive effects on human health. The health-promoting effects of flavan 3-ols, especially those of green tea, are of scientific and public interest. Furthermore, they play a crucial role in defense against pathogens of tea. Therefore, biosynthesis of these flavonoid compounds was investigated. The anthocyanidin reductase enzyme recently described from Arabidopsis and Medicago was shown to be present in tea with very high activity and produces epicatechin as well as epigallocatechin from the respective anthocyanidins, thus explaining the very high contents of these compounds. A strong combined dihydroflavonol 4-reductase/leucoanthocyanidin 4-reductase activity was demonstrated and catalyzes the key steps in catechin and gallocatechin formation. Together with the enzyme activities and substrate specificities of the preceding enzymatic reactions, the biosynthesis of the most prominent flavonoids of tea is elucidated.

Acyltransferases↗

PubMed2004

Improved cerebral protection through replacement of residual intracavital air by carbon dioxide: a porcine model using diffusion-weighted magnetic resonance imaging.

BACKGROUND: Major risk of central or peripheral organ damage is attributed to air embolism from incompletely de-aired cardiac chambers after cardiac operations. Replacement of air by carbon dioxide insufflation into the thoracic cavity is widely used. Diffusion-weighted magnetic resonance imaging of the brain detects ischemia within minutes after onset. The reversibility of ischemia in cerebral tissue after massive gaseous emboli has not yet been described. METHODS: After selective catheterization of a common carotid artery in 15 pigs, boli of 1 mL/kg body weight of air (n = 5) or carbon dioxide (n = 5, "low dose") were applied. Five pigs received 2 mL/kg body weight of carbon dioxide ("high dose"). Diffusion-weighted magnetic resonance imaging of the brain was performed 2, 5, 10, 15, and 25 minutes after embolization. RESULTS: All animals of the "air" group showed important circulatory reactions leading to death of 2 animals. In the whole group, diffusion-weighted magnetic resonance imaging revealed irreversible hyperintense signals in both hemispheres. In the low-dose group, no change in signal intensity was observed in 2 pigs, and 3 others showed reversible changes in signal intensity, without important circulatory reactions. In 3 animals of the high-dose group, hyperintense signals were reversible, but 2 others presented with bilateral, irreversible signals in diffusion-weighted magnetic resonance imaging, accompanied by minor circulatory reactions. CONCLUSION: In contrast to the dramatic effect of air emboli, identical quantities of carbon dioxide injected into cerebral arteries of the pigs were not associated with major clinical symptoms. The early reversibility of ischemic reactions visualized in diffusion-weighted magnetic resonance imaging encourages the use of carbon dioxide insufflation as a protective method in cardiac surgery.

Animals↗

PubMed2004

Elimination of microbubbles from the extracorporeal circuit: dynamic bubble trap versus arterial filter.

BACKGROUND: Open heart surgery is associated with important risk of cerebral and peripheral organ dysfunction, attributed in part to microbubbles generated in or not eliminated from the ECC. For elimination of microbubbles, a dynamic bubble trap (DBT) was developed for the arterial line of ECCs. METHODS: Bubble eliminating properties of an arterial filter were evaluated in four CABG patients and compared to the performance of the DBT in four patients. One patient received both devices. RESULTS: Elimination of bubbles between 40-120 microm was significantly higher with the DBT (88% vs. 57% with arterial filter, p=0.034). Reduction of bubbles below 40 microm was equivalent in both groups. The combination of both devices was most effective (94% for bubbles >40 microm). CONCLUSION: Arterial filter and DBT are equally effective in elimination of smaller gas bubbles. However, bigger bubbles possibly causing cerebral and peripheral organ damage are eliminated to a greater degree by the DBT.

Coronary Artery Bypass↗

PubMed2004

Routine microbiological screening in septic patients in a cardiac surgical intensive care unit.

INTRODUCTION: Patients in a surgical intensive care unit (ICU) have a high incidence of nosocomial infections which often lead to septic shock and death. Since specific antibiotic treatment is often difficult, it is recommended that routine nose/throat swabs be obtained in order to have a better idea of the causative agent when a systemic inflammatory response occurs in a given patient. MATERIALS AND METHODS: In 1435 patients in a cardiac surgical ICU, routine nose/throat swabs were taken thrice a week and tested for microorganisms and systemic inflammation. Blood cultures were also obtained. Antibiotic treatment was given to cover the microbes from the nose/throat swabs. Alternatively, an empirical antibiotic therapy was given to patients whose swabs had tested negative. RESULTS: Of the 86 patients with systemic inflammation, 29 had blood cultures positive for microbes. Of these, 18 received a specific antibiotic therapy based on their positive nose/throat cultures prior to the return of the blood cultures from the laboratory. However, only 11 patients tested positive for the same microbes on routine swabs and blood cultures. While positive routine swabs are quite specific to sepsis when there is a systemic inflammatory response, routine swabs are not a suitable screening tool due to their low sensitivity. CONCLUSION: Routine nose/throat swabs led to earlier specific antibiotic treatment in only 22 % of patients with clinical signs of systemic inflammation. In 36 % of cases, the organisms detected in the routine swabs and blood cultures were not identical. Hence, we believe that routine swabs are of limited value in instituting earlier, specific antibiotic therapy in septic patients.

Antibiotic Prophylaxis↗

PubMed2003

Do surface modifying additives (SMA) influence blood loss and thrombogenicity in conventional cardiopulmonary bypass for coronary artery bypass grafting?

Cardiopulmonary bypass (CPB) leads to activation of the coagulation and fibrinolytic cascades, partially associated with foreign surface contact. Hemorrhage and the need for blood products is associated with rising cost and increased risk of infection. Treatment with surface modifying additives (SMA) has been shown to reduce thrombogenicity and improve biocompatibility. 76 elective CABG-patients were randomly assigned to surface modifying additives (group I, n=39) or untreated circuits that were otherwise identical (group II, n=37). Measurements of coagulation activity and fibrinolysis, platelet count and function were made. The postoperative blood loss and blood product replacement was also assessed. Thrombin formation measured by prothrombin fragments 1+2 (5.7+/-0.4 nmol/l vs. 5.6+/-0.4 nmol/l), fibrinolytic activity measured by plasmin-antiplasmin complex (1752.6+/-216.8 microg/l vs.1180.0+/-74.8 microg/l) and the postoperative platelet count and function did not differ significantly between the two groups. Blood loss and transfusion requirements were slightly lower in the SMA group. The treatment of extracorporeal surfaces with surface modifying additives does not appear to reduce coagulation disorders and bleeding after conventional CPB.

Aged↗

PubMed2003

Performance of stentless versus stented aortic valve bioprostheses in the elderly patient: a prospective randomized trial.

OBJECTIVES: Although stentless aortic bioprostheses are believed to offer improved outcomes, benefits remain unsubstantiated. The aim of our study was to compare stentless with stented bioprostheses, with regard to postoperative changes in left ventricular mass and hemodynamic performance, in the elderly patient. METHODS: Forty patients with aortic stenoses, over the age of 75 years, were randomized to receive either the stented Perimount (n=20) or the stentless Prima Plus (n=20) bioprosthesis. Left ventricular mass regression, effective orifice area, ejection fraction and mean gradients were evaluated at discharge, 6 months and 1 year after surgery. RESULTS: Overall a significant decrease in left ventricular mass was found 1 year postoperatively. However, there was no significant difference in the rate of left ventricular mass regression between the groups. Furthermore, 1 year postoperatively, the hemodynamic performance of the valves and the change in the ejection fraction did not differ between the groups. CONCLUSIONS: Our study shows that in a randomized cohort of elderly patients with aortic stenosis, we were not able to detect significant differences, with regard to hemodynamic performance and regression of left ventricular mass, between the stentless and stented valve groups. To our surprise, previously reported findings of non-randomized trials that showed faster and more complete regression of left ventricular mass and hemodynamic benefits of stentless valves were not reproducible.

Aged↗

PubMed2003

Thoracic epidural anesthesia does not influence the incidence of postoperative atrial fibrillation after beating heart surgery.

BACKGROUND: At least 20 - 30 % of patients undergoing coronary artery bypass graft surgery (CABG) or beating-heart surgery develop postoperative atrial fibrillation (AF). We evaluated the effect of thoracic epidural anesthesia (TEA) on the occurrence of postoperative AF in patients submitted to CABG without cardiopulmonary bypass (OPCABG). METHODS: We performed a retrospective analysis of 125 patients undergoing myocardial revascularization. Early postoperative incidence of AF was compared between three groups of patients - 50 after conventional CABG, 45 after OPCABG, and 30 after OPCABG combined with TEA intraoperatively and postoperatively. Clinical profile of the patients, including factors with a potential influence on postoperative AF was matched for groups. RESULTS: Postoperative AF occurred in 13.3 % of the TEA-treated patients, in 17.7 % of the patients in the OPCABG group, and in 26 % of the patients in the CABG group. This difference did not carry any statistical significance. Risk factors and incidence of postoperative complications were comparable in all groups. CONCLUSION: TEA has no effect on the incidence of postoperative AF in patients undergoing beating-heart surgery.

Aged↗

PubMed2003

Five-year follow-up after long plaque-bridging coronary arteriotomy for diffuse coronary artery disease.

UNLABELLED: Long arteriotomy bridging a stenotic plaque or segment may improve runoff in diffuse coronary artery disease. However, patency might be impaired due to vascular wall pathology. OBJECTIVE: To determine the patency rates of plaque-bridging arteriotomy compared to conventional coronary artery bypass grafting. METHODS: Between May 1995 and December 1998, 104 patients with a mean age of 65 +/- 7 years received a long arteriotomy extending over a heavily plaqued area in an effort to treat their diffuse coronary artery disease. The length of the arteriotomy ranged from 14 mm to 40 mm. We retrospectively analyzed the intra-individual bypass graft patency rates by multidetector-computed tomography or coronary angiography. RESULTS: The mean follow-up was 5 years. There were 5 (4.8 %) early and 10 (9.6 %) late deaths, three non-cardiovascular. Graft patency for internal thoracic artery (ITA) to left anterior descending artery (LAD) (plaque-bridging) was 94.8 %, for saphenous vein graft (SVG) to circumflex artery (CX) (plaque-bridging) 67 %, and SVG to right coronary artery (RCA) (plaque-bridging) 79.5 %. Graft patency for ITA to LAD (conventional) was 94.9 %, for SVG to CX (conventional) 72.4 %, and SVG to RCA (conventional) 75 %. Freedom from angina was 82.8 % (n = 58/70), freedom from myocardial infarction was 95.7 % (n = 67/70), freedom from reintervention was 91.4 % (n = 64/70) and freedom from reoperation was 100 % (n = 70/70). CONCLUSION: Diffuse coronary artery disease can be treated by extending the arteriotomy over the plaques, with graft patency rates comparable to bypass grafts onto less diseased segments.

Aged↗

PubMed2002

[Successful reoperation of a ruptured aortic arch aneurysm in Takayasu arteritis].

Successful reoperation of a ruptured aortic arch aneurysm in a patient with Takayasu's disease. Takayasu's disease is an inflammatory arteriopathy that often progresses to stenosis or aneurysms of the large arteries of the aortic arch. In this connection aneurysms of the ascending aorta are rare. We report the case of a 33 years old female with a ruptured aneurysm of the ascending aorta complicated by a former operation of a truncobicarotidal bypass and severe sclerosis. After ascending aorta and aortic arch replacement was performed in deep hypothermia circulatory arrest we could discharge the patient in good condition on the 11. postoperative day.

Adult↗

PubMed2002

Sutured coronary artery grafting utilizing the Heartflo anastomosis device--first clinical experiences.

BACKGROUND: The Heartflo device was developed to facilitate consistency in distal coronary anastomosis quality. The device automates the suturing process during the anastomosis procedure via simultaneous delivery of ten standard 7-0 polypropylene sutures through the graft and the coronary vessel wall. METHODS: In 30 elective coronary artery bypass patients, one distal anastomosis was intentionally performed with the anastomosis device. Device success was stated if a patent anastomosis with a minimal flow of 50 ml/min resulted, additional stitches were counted if bleeding occurred. RESULTS: 4 cases of device failure occurred in the first 5 patients. The subsequent patients were operated without any mechanical problems. In 16 patients (53 %), a patent anastomosis with a mean flow of 75 +/- 6 ml/min using 1.7 +/- 0.3 additional stitches was achieved. Anastomoses were completed in 19.0 +/- 0.7 min; postoperative course was uneventful in all patients. CONCLUSIONS: We have shown that coronary anastomoses are feasible using the Heartflo device, representing a promising step on the way to automated coronary anastomoses. Its application is still limited by the size and tissue quality of the target vessel and difficult suture management during the anastomosis procedure.

Aged↗

PubMed2002

Left ventricular thrombus capture by an intra-aortic filter device.

Left ventricular aneurysmectomy in patients with mobile, protruding thrombi is associated with increased risk of neurological complications due to loss during left ventricular luxation or embolisation of residual thrombotic material after incomplete removal. Embolisation can be prevented by application of an intra-aortic filter device. Here, we report on a case involving an important left ventricular thrombus captured in a patient referred for coronary artery bypass grafting, left ventricular aneurysmectomy, and thrombectomy.

Adult↗

PubMed2002

Optimal carbon dioxide application for organ protection in cardiac surgery.

BACKGROUND: Cardiac surgery is associated with an important risk of central or peripheral organ damage, attributed in part to air embolism from incompletely deaired cardiac chambers. Insufflation of carbon dioxide into the thoracic cavity is widely used for organ protection in cardiac surgery. METHODS: In patients operated on through a sternotomy, the gas was insufflated through a standard cardioplegia line (group I, n = 10) or a Jackson-Pratt drain (group II, n = 10), with flow rates of 2, 4, and 6 L/min. In patients undergoing mitral valve surgery through a right anterolateral minithoracotomy, application through a gas port (group III, n = 10) was compared with application through a Veress needle (group IV, n = 10). In groups I and IV measurements were repeated with a gauze sponge to divert the gas stream. RESULTS: At a flow of 2 L/min, carbon dioxide levels in the thoracic cavity reached 52% +/- 30% in group I and increased to 81% +/- 27% when a gauze sponge was used. In group II a level of 91% +/- 5% was achieved. In minimally invasive procedures carbon dioxide levels reached 92% +/- 6% in group III and 60% +/- 25% in group IV without a gauze sponge and 97% +/- 2% in group IV with a gauze sponge. Increasing flow rates from 2 to 6 L/min decreased carbon dioxide levels in the thoracic cavity. Arterial blood gas analysis did not reveal critical levels of partial pressure of carbon dioxide at any time. CONCLUSIONS: For optimized carbon dioxide concentrations during cardiac procedures, jet effects in the thoracic cavity have to be avoided. The highest levels were achieved with infusion lines covered by a gauze sponge or a perforated drain for conventional operations and a sponge-covered Veress needle or a gas port for minimally invasive approaches.

Carbon Dioxide↗

PubMed2001

Purification and antigenicity of flavone synthase I from irradiated parsley cells.

Flavone synthase I, a soluble 2-oxoglutarate-dependent dioxygenase catalyzing the oxidation of flavanones to flavones in several Apiaceae species, was induced in parsley cell cultures by continuous irradiation with ultraviolet/blue light for 20 h. The enzyme was extracted from these cells and purified by a revised purification protocol including the fractionation on hydroxyapatite, Fractogel EMD DEAE, and Mono Q anion exchangers, which resulted in an apparently homogeneous flavone synthase at approximately 10-fold higher yield as compared to the previous report. The homogeneous enzyme was employed to raise an antiserum in rabbit for partial immunological characterization. The specificity of the polyclonal antibodies was demonstrated by immunotitration and Western blotting of the crude ammonium sulfate-fractionated enzyme as well as of the enzyme at various stages of the purification. High titer cross-reactivity was observed toward flavone synthase I, showing two bands in the crude extract corresponding to molecular weights of 44 and 41 kDa, respectively, while only the 41 kDa was detected on further purification. The polyclonal antiserum did not cross-react with recombinantly expressed flavanone 3beta-hydroxylase from Petunia hybrida or flavonol synthase from Citrus unshiu, two related 2-oxoglutarate-dependent dioxygenases involved in the flavonoid pathway.

Antibody Specificity↗

PubMed2001

Incidence of gastrointestinal complications in cardiopulmonary bypass patients.

Gastrointestinal complications after cardiac surgery are associated with a high mortality rate. Because of the absence of early specific clinical signs, diagnosis is often delayed. The present study seeks to determine predictive risk factors for subsequent gastrointestinal complications after cardiosurgical procedures. Within a 1-year period, a total of 1116 patients who had undergone open heart surgery with cardiopulmonary bypass were prospectively studied for gastrointestinal complications. To determine predictive factors, all case histories of the patients were analyzed. Of the 1116 patients, 23 (2.1%) had gastrointestinal complications during the postoperative period, 10 of whom had to undergo subsequent abdominal surgery. Of these 23 patients, 20 died. Early gastrointestinal complications, which occurred mostly on postoperative days 6 or 7, consisted of bowel ischemia or hepatic failure. Late complications were gastrointestinal bleeding, pseudomembranous colitis, cholecystitis, and septic rupture of a spleen. The relative risk for abdominal complications after cardiopulmonary bypass was highly increased in association with (1) a cardiac index less than 2.0 l/min-1/(m2)-1, (2) postoperative onset of atrial fibrillation, (3) emergency surgery, (4) need for vasopressors, (5) need for intraaortic balloon counterpulsation, and (6) need for early redo thoracotomy due to surgical complications. All patients with necrotic bowel disease had elevated serum lactate levels. Furthermore, cardiopulmonary bypass and aortic clamping times were significantly prolonged in patients who developed gastrointestinal complications. A number of predictive factors contribute to the development of gastrointestinal complications after cardiopulmonary bypass surgery. Knowledge of these factors may lead to earlier identification of patients at increased risk and may allow more efficient and earlier interventions to reduce mortality.

Aged↗