Biomedical subjects

Yves Van Belleghem

Publications and source records attributed to Yves Van Belleghem.

14 recordsLinked to original sources

PubMed2006

Stentless and stented aortic valve replacement in elderly patients: Factors affecting midterm clinical and hemodynamical outcome.

OBJECTIVE: To report on the midterm results of aortic valve replacement (AVR) with stented and stentless bioprosthesis in an elderly population by analyzing the factors affecting survival and hemodynamical performance. METHODS: In a retrospective study, 145 patients with a Toronto stentless prosthesis are compared with 110 patients with a stented Carpentier-Edwards valve. The 5- to 10-year clinical outcome, transprosthetic gradients, and early and late left ventricular mass (LVM) regression are analyzed in view of specific prosthesis- and patient-related factors. RESULTS: Actuarial survival at 5 years is 82% after stentless AVR versus 68% after stented AVR (p < 0.001) in elderly patients. However, there was no difference in survival at 8 years, being 55.9% and 59.5%, respectively. Univariate analysis revealed that advanced age at the time of operation, NYHA class IV, use of a stented xenograft, presence of patient-prosthesis mismatch (PPM) (IEOA < or = 0.85 cm2/m2), and severe preoperative left ventricular (LV) hypertrophy (LVMI > 180 g/m2) affected survival adversely. But multivariate analysis determined only age, NYHA class IV and excessive LV hypertrophy as independent predictors of late mortality. Stented and stentless xenografts were equally effective in terms of transprosthetic gradients and LVMI regression. The use of a stentless valve significantly reduced the occurrence of PPM (18% vs 41%, p < 0.01). Early LVMI regression at 1 year was optimized by the avoidance of PPM, indicated by a higher absolute (43.7+/-28.3 g/m2 vs 58.6+/-33.8 g/m2, p = 0.003) and relative (25.0+/-12.7% vs 31.4+/-14.9%, p=0.004) mass regression. However, late LV remodeling was predominantly affected by systemic hypertension and severe preoperative LV hypertrophy, resulting in the incomplete LVMI resolution in 61.3% and 66.7% of these patients, respectively. CONCLUSION: In elderly patients, aortic valve replacement appears to be equally effective with a stentless or stented bioprosthesis. Midterm clinical outcome is mainly determined by patient-related factors such as age, advanced NYHA class, and severity of preoperative LV hypertrophy. Regarding post-AVR left ventricular remodeling, patient-prosthesis mismatch influences the early phase, whereas arterial hypertension affects the late regression more. However, the left ventricular remodeling is continuously compromised by the preoperative presence of excessive hypertrophy, despite the efficacy of the aortic valve replacement.

Aged↗

PubMed2005

Stentless vs. stented aortic valve replacement: left ventricular mass regression.

The aim of this retrospective study was to evaluate the time-related regression of left ventricular hypertrophy after stentless vs. stented aortic valve replacement. From January 1992 to December 2002, 145 patients had a Toronto stentless porcine valve and 106 had a stented Carpentier-Edwards aortic valve replacement. Over a 10-year follow-up, survival was superior in the Toronto group vs. the Carpentier-Edwards group (84% vs. 74% at 4 years; 78% vs. 68% at 6 years; p < 0.001). A significant and constant reduction of peak and mean transvalvular gradients after valve replacement resulted in substantial regression of left ventricular mass index in both groups, which did not reach statistical significance. However, this phenomenon stopped at 3 years, and left ventricular mass index increased slowly after 5 years. Stentless and stented bioprostheses both showed good early and late clinical and hemodynamic outcomes, with the advantage of better midterm survival for stentless xenografts.

Adult↗

PubMed2005

Aortic valve replacement with Toronto SPV in elderly patients: 10-year results.

A retrospective assessment of clinical and echocardiographic variables was performed in 145 patients who received a Toronto SPV aortic valve replacement. The majority (90%) of these elderly patients (mean age, 75.5 +/- 7.4 years) were preoperatively in New York Heart Association class III-IV. Operative mortality was 4.8%. Follow-up was complete up to 10 years and revealed few valve-related complications: thromboembolism (7), bleeding (4), and prosthesis dysfunction necessitating reoperation (3). Late mortality was cardiac-related in 11.7% and noncardiac-related in 17.2%. Actuarial survival was 83% at 5 years and 63% at 8 years. Echocardiography showed low transvalvular gradients (peak, 17.5 +/- 7.5 mm Hg; mean, 9.2 +/- 4.2 mm Hg) resulting in a significant reduction in left ventricular mass index during the first 3 years. Independent of the transprosthetic gradient, left ventricular mass index tended to increase again beyond the 5th year, which correlated positively with the presence of arterial hypertension in this older population. The Toronto SPV bioprosthesis offers an aortic valve substitute with excellent long-term hemodynamics, resulting in significant early left ventricular mass regression. Considering the limitations of this selected elderly population, the clinical outcome and survival up to 10 years are encouraging, with few observed valve-related events.

Aged↗

PubMed2005

Relation between neurocognitive impairment, embolic load, and cerebrovascular reactivity following on- and off-pump coronary artery bypass grafting.

OBJECTIVES: To evaluate the effect of on-pump and off-pump coronary artery bypass grafting (CABG) on postoperative cognitive impairment and cerebrovascular reactivity, with attention for the perioperative high-intensity transient signals (HITS). DESIGN: A prospective comparative study. SETTING: Urban university hospital. PATIENTS: Candidates for cardiac surgery. METHODS: Measurement of HITS as a reflection of embolic load was performed in 50 patients (on-pump CABG, n = 32; off-pump CABG, n = 18). To measure cognitively induced cerebrovascular reactivity, cerebral blood flow velocity (BFV) was measured preoperatively in 66 patients, early postoperatively (after 6 days) in 63 patients, and late postoperatively (after 6 months) in 44 patients during five cognitive tasks. In the same session, seven standardized neuropsychological tests were administered. RESULTS: A higher embolic load was found in the on-pump group (p < 0.01). In the on-pump group, aortic cannulation was the most important HITS-prone surgical maneuver. Repeated-measures multivariate analysis of variance (using surgical technique as between-subjects factor and significant differences between both groups as covariates) on the group data revealed no significant differences in neuropsychological performance and BFV immediately after surgery or at 6 months after surgery, compared with preoperative performance. No main effect of surgery was found for neuropsychological performance and BFV. No significant correlations were found between the number of HITS and the degree of postoperative neuropsychological impairment. Individual comparisons revealed that 60% (59.4% in the on-pump group; 61.1% in the off-pump group) of the patients undergoing CABG showed evidence of cognitive impairment soon after surgery. In 24.2%, the cognitive sequelae persisted at 6 months follow-up (31.8% in the on-pump group; 9.1% in the off-pump group). The cognitive impairment index (sum of impaired neuropsychological tests) showed a significant difference after 6 months between both surgery groups with fewer neurocognitive tests that remained impaired in the off-pump group. CONCLUSIONS: In off-pump surgery, significantly fewer HITS were observed. On an individual level, more favorable results in neuropsychological test performance were demonstrated in the off-pump group after 6 months. The number of HITS showed no correlation with degrees of early and late postoperative neuropsychological impairment.

Age Distribution↗

PubMed2004

Bovine glue (BioGlue) is catabolized by enzymatic reaction in the vascular dog model.

PURPOSE: The aim of the study is to explore the feasibility, patency, and histologic changes of a sutureless vascular anastomotic technique using biological glue as sole fixation method. DESCRIPTION: Eight mongrel dogs (+/-15 kg) underwent direct reanastomosis of their transsected iliac arteries. Both ends were placed on a 5-mm balloon and the anastomosis was secured with biological glue (BioGlue, Cryolife, Kennesaw, GA). No intravascular suture material was used. All survivors were angiographically controlled for patency after 6 weeks and 3 months. Then the animals were euthanized and tissues were obtained for histologic and pathologic examination by light and electron microscopy. EVALUATION: All procedures were successful except for 1 animal that died of uncontrollable bleeding at the anastomotic site. All first-time angiographically controlled grafts except three were patent. One animal showed manifest signs of fungal infection. Histology detected early granulocyte infiltration with an important enzymatic reaction adjacent to the surface of glue. Later on, the glue gradually regressed to disappear completely. Fibroblastic neointimal lining was noticed in most of the anastomoses, with some marked differences in the endothelium compared with normal. CONCLUSIONS: Good permeability (57%) was observed in this new sutureless anastomotic technique in the canine model. In contrast to previous reported studies we noticed a clear enzymatic breakdown of the glue before total disappearance. It is not yet known to what extend use of the bovine glue was responsible for this phenomenon.

Anastomosis, Surgical↗

PubMed2004

Transforming growth factor-beta-induced transition of fibroblasts: a model for myofibroblast procurement in tissue valve engineering.

BACKGROUND AND AIM OF THE STUDY: The selection of a suitable cell type for scaffold seeding, its isolation and adequate expansion in vitro remains a major challenge in tissue valve engineering. The study aim was to establish a model for efficient procurement of myofibroblasts for in-vitro seeding using fibroblasts as progenitor cells. METHODS: Dermal and arterial mesenchymal cells from human (hDMC1.1 and hAMC1.1) and sheep (sDMC1.1 and sAMC1.1) were isolated by sequential culture. Cell isolates were characterized by stringent criteria based on morphology, immunocytochemistry using antibodies to vimentin, cytokeratin, prolyl 4-hydroxylase, smooth muscle alpha-actin (alpha-SMA) and smooth muscle myosin, and by Western blotting for alpha-SMA and N-cadherin. Cultures with less than 10-20% alpha-SMA-positive cells were considered to be fibroblastic. Cells were subsequently transdifferentiated with the cytokine transforming growth factor-beta1 (TGF-beta1) during five days, and then evaluated morphotypically, by immunocytochemistry, and by Western blotting. The metabolic and functional properties of TGF-beta1-treated and untreated colonies were compared by measuring the expression of extracellular proteins (collagen type 1 and tenascin-C) and by a collagen matrix contraction assay. RESULTS: TGF-beta1 successfully transformed both human and sheep fibroblasts to metabolically active and functional myofibroblasts based on stringent criteria for myofibroblast characterization. Alpha-SMA positivity of 100% was obtained in all cases (hDMC1.1, hAMC1.1, sDMC1.1, and sAMC1.1) after transformation compared to less than 50% in the non-transformed state (hAMC1.1, 17%; hDMC1.1, 10%; sAMC1.1, 43%; and sDMC1.1, 30%). This observation was further supported by increased contractility and an up-regulation of extracellular protein production in transdifferentiated cells. CONCLUSION: Untreated arterial cell isolates were, at best, less than 50% alpha-SMA-positive. By allowing procurement of high densities of myofibroblasts in a relatively short time, the model was seen to be a potentially useful tool in tissue valve engineering, at least in investigations using autologous cells in the sheep model.

Actins↗

PubMed2003

Modified stentless porcine valve enhances accelerated cuspal calcification in the juvenile sheep model.

OBJECTIVE: Stent mounting of any bioprosthesis, induces a loss of mobility and reduces the effective valve orifice. By contrast, for stentless procedures, the higher surgical technicality remains a major obstacle for many surgeons. In an attempt to facilitate the insertion of the stentless porcine aortic valve (Toronto SPV), we tried to alter the design by lowering the invasive profile at the depth of the sinuses on both coronary sites. This could theoretically facilitate the implant of the modified stentless valve with an easygoing single layer suture at the challenging subcoronary level and make it more attractive for every surgeon. METHODS: Modifications of the standard model were done by lowering the profile at the depth of the sinuses on both coronary sites, whether by plication or excision of the protruding porcine aortic wall at the nadir of each coronary sinus. Nine juvenile sheep underwent implantation of stentless porcine aortic valves in pulmonary position: 3 standard Toronto SPV, 3 plicated Toronto SPV and 3 excised Toronto SPV. In each series, valves were explanted after 3 months. Valves were analyzed. RESULTS: The cusps of standard Toronto SPV were perfectly functioning and pliable, without visible calcification after three months. The calcium content of the cusps was less than those in the plicated and excised Toronto SPV (2.4 +/- 0.7 microg/mg versus 10.8 +/- 5.9 and 6.7 +/- 3.4 microg/mg). In the plicated and excised valves, calcification of the cusp was more pronounced in the commissural region (3.9 +/- 1.9, 29.0 +/- 16.7, 13.8 +/- 9.5 microg/mg in the standard, plicated and excised Toronto SPV, respectively). On the other hand, the aortic wall from the plicated Toronto SPV had more calcium than that from the other groups (53.6 +/- 6.3, 41.2 +/- 7.1, 45.2 +/- 7.4 microg/mg in the plicated, standard and excised Toronto SPV, respectively). CONCLUSIONS: The modification of stentless porcine valve enhanced accelerated cuspal calcification in the commissural region. It accentuated that the correct implantation technique for stentless procedures is extremely important in order to prevent early degeneration.

Animals↗

PubMed2003

Lower anticoagulation for mechanical heart valves: experience with the ATS bileaflet valve.

BACKGROUND: The design of the bileaflet ATS (ATS Medical Inc., Minneapolis, USA) mechanical valve incorporates an open pivot at the hinge mechanism. Total washout of the blood at the pivot area was observed using 3-D computational fluid dynamics modelling. This phenomenon could make the valve less vulnerable to clot formation in patients without major thromboembolic risk factors. METHODS: From January 1993 to June 1999, 286 consecutive patients had the ATS valve inserted in the aortic position. Patients were divided into two groups. Group 1 comprised all patients in regular sinus rhythm with good left ventricular function (144 patients). Group 2 included patients in non-sinus rhythm and/or with large hypocontractile left ventricles (142 patients). The anticoagulation regime in group 1 was used to obtain an international normalised ratio (INR) between 1.5 and 2.5. This contrasts with our regular aim to maintain the INR strictly between 2.5 and 3.5 for all mechanical valves, as achieved in group 2. RESULTS: The follow-up period (99% completeness) ranged from 18 to 84 months. Survival (Kaplan-Meier) was 97 and 98% and 92 and 81% at 1 and 5 years in group 1 and group 2, respectively (P = 0.12). Log rank analysis failed to detect a statistical difference in thromboembolism or bleeding between both groups (P > 0.05). However, trends were in favour of group 1. Univariate analysis selected poor ventricular function and an 'erratic' INR value (P = 0.002) as risk factors for death. The sole independent risk factor for bleeding was the use of aspirin (P = 0.025). CONCLUSIONS: The excellent group 1 data and outcome encouraged us to continue our low intensive anticoagulation regime and perhaps should be regarded as a new concept for treatment of selected mechanical valve patients.

Journal Article↗

PubMed2003

Intermittent nitric oxide combined with intravenous dipyridamole in a piglet model of acute pulmonary hypertension.

UNLABELLED: Continuous administration of inhaled nitric oxide is now widely used as a potent and selective pulmonary vasodilator. We have evaluated the effects of IV dipyridamole, a cyclic guanosine monophosphate (cGMP) phosphodiesterase inhibitor, on the magnitude and duration of action of inhaled nitric oxide (NO)-mediated pulmonary vasodilation. We hypothesized that inhibition of cGMP degradation could augment and prolong the pulmonary vasodilating effects of NO and allow for intermittent NO inhalation. In eight anesthetized and mechanically ventilated piglets, IV U-46619, a thromboxane A(2) analog, was used to induce pulmonary hypertension. The effects of 2, 5, and 10 ppm of NO, delivered during 4 min for each concentration and followed by a 10-min NO-free interval after each NO concentration, were evaluated without and with dipyridamole. Pulmonary vascular resistance decreased from 825 +/- 49 dynes. s. cm(-5) (U-46619) to 533 +/- 48 dynes. s. cm(-5) (10 ppm NO) (P < 0.05 versus U-46619) and 396 +/- 42 dynes. s. cm(-5) (dipyridamole 10 microg kg-1x min-1 and 10 ppm NO) (P <0.05 versus NO), and cardiac output increased from 1.93 +/- 0.09 L/min to 2.03 +/- 0.13 L/min and 2.60 +/- 0.30 L/min (P < 0.05 versus NO). Mean arterial blood pressure decreased from 90 +/- 5 mm Hg (10 ppm NO) to 75 +/- 3 mm Hg (dipyridamole plus 10 ppm NO) (P < 0.01). The pulmonary vasodilation obtained with NO alone could be prolonged from 12 to 42 min when inhaled NO was combined with IV dipyridamole, accounting for a time-weighted reduction in NO exposure by 72%. We conclude that dipyridamole augments the effects of NO on right ventricular afterload, allows for intermittent NO inhalation, and can significantly reduce exposure to NO. IMPLICATIONS: IV dipyridamole prolongs the action of inhaled nitric oxide (NO) in a piglet model of acute pulmonary hypertension. Intermittent NO inhalation combined with IV dipyridamole decreases pulmonary artery pressure for a prolonged period of time and reduces exposure to NO.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2003

Lower-intensity anticoagulation for mechanical heart valves: a new concept with the ATS bileaflet aortic valve.

BACKGROUND AND AIM OF THE STUDY: The design of the bileaflet ATS mechanical valve incorporates an open pivot at the hinge mechanism. Total washout of blood at the pivot area seen using three-dimensional computational fluid dynamics modeling may make the valve less vulnerable for clot formation in patients without major thromboembolic risk factors. METHODS: Between January 1993 and June 1999, the ATS valve was implanted in the aortic position in 286 consecutive patients. Patients were allocated prospectively to two groups: group 1 comprised patients in regular sinus rhythm with good left ventricular (LV) function (n = 144); group 2 included patients in non-sinus rhythm and/or with large hypocontractile left ventricles (n = 142). The anticoagulation regime in group 1 was to achieve an INR of 1.5-2.5, rather than to maintain INR strictly at 2.5-3.5 for mechanical valves (as in group 2). RESULTS: Follow up was 99% complete and ranged from 50 to 120 months. Survival (Kaplan-Meier) was respectively 95% and 90% and 90% and 83% at 2 and 5 years in favor of group 1 (p = 0.0055). Multivariate analysis selected advanced age, poor LV function and 'erratic' INR as risk factors for death. Log rank analysis failed to detect any statistical difference in thromboembolism. Bleeding occurred more frequently in group 2 (p = 0.018); independent risk factors for bleeding were the presence of aspirin (p = 0.0164) and advanced age (p = 0.02). CONCLUSION: The excellent group 1 data and outcome encouraged continuation of the low-intensity anticoagulation regime, and should be regarded as a new concept for the treatment of mechanical valve patients.

Aged↗

PubMed2002

Diagnosis of myocardial perforation by a Greenfield filter made by transesophageal echocardiography.

Greenfield filters have been successfully used to prevent pulmonary embolism in selected patients. However, various complications have been described. A patient is presented in whom a Greenfield filter migrated to the right atrium, and subsequently perforated the right atrial wall. The diagnosis was made by transesophageal echocardiography and the filter removed surgically. This case emphasizes the role of transesophageal echocardiography in the management of migrated Greenfield filters.

Aged↗

PubMed2002

Effects of off-pump coronary surgery on the mechanics of the respiratory system, lung, and chest wall: Comparison with extracorporeal circulation.

OBJECTIVE: To compare the effects of cardiac surgery with and without extracorporeal circulation on the mechanics of the respiratory system, lung, and chest wall. We also determined the time course of those effects. DESIGN: Prospective, controlled study. SETTING: An eight-bed, cardiac-surgical intensive care unit at a university hospital. PATIENTS: Two groups of patients scheduled for elective coronary bypass surgery were studied: ten patients with extracorporeal circulation and 13 patients without extracorporeal circulation. INTERVENTIONS: Measurement of esophageal pressure after insertion of an esophageal balloon catheter to separate respiratory system mechanics into lung and chest wall components. Measurements were performed preoperatively after induction of anesthesia (control), immediately postoperatively at arrival in the intensive care unit (time 1), and after 3 hrs (time 2). In 12 of the 23 patients, measurements were also performed 6 hrs postoperatively (time 3). MEASUREMENTS AND MAIN RESULTS: No significant differences concerning demographics or surgical procedure were noticed between the two groups. Respiratory system, chest wall, and lung mechanics were obtained using the technique of rapid airway occlusion during constant-flow inflation. In both the group with and without extracorporeal circulation there was a significant increase in static and dynamic elastance of the respiratory system and lung at times 1 and 2, which tended to decrease again at time 3; chest wall elastance significantly increased at times 2 and 3 in the group without extracorporeal circulation, whereas the increase in chest wall elastance in the group with extracorporeal circulation occurred earlier (also at time 1). Additional resistance of the respiratory system and lung remained unchanged; chest wall resistance, however, significantly increased in both groups. Work of breathing significantly increased in both groups at times 1 and 2. There was a significant reduction in the Pao2/Fio2 ratio in both groups at times 2 and 3. No significant differences between the groups at any moment were noticed. CONCLUSIONS: Coronary bypass surgery with and without extracorporeal circulation results in dramatic impairment of respiratory system mechanics. Based on respiratory system mechanics, early extubation after coronary artery bypass grafting should be performed with caution, no matter whether the off-pump or cardiopulmonary bypass technique is used.

Aged↗

PubMed2002

Intravenous dipyridamole enhances the effects of inhaled nitric oxide and prevents rebound pulmonary hypertension in piglets.

Inhaled nitric oxide (NO) is increasingly used in the treatment of pulmonary hypertension, despite its potential toxicity and the risk of life-threatening rebound pulmonary hypertension upon its discontinuation. We investigated whether i.v. dipyridamole, a cGMP phosphodiesterase inhibitor, increased the effects of inhaled NO and prevented rebound pulmonary hypertension. In 14 anesthetized and mechanically ventilated piglets, pulmonary hypertension was induced with U-46619, a thromboxane A(2) analogue. Response to NO and rebound pulmonary hypertension were evaluated without and with i.v. dipyridamole. Low-dose dipyridamole (10 micro g/kg/min) increased cardiac output and augmented the effects of inhaled NO on pulmonary vascular resistance, with marginal additive effect on mean pulmonary artery pressure. Pulmonary vascular resistance decreased from 904 to 511 (20 parts per million NO) (p < 0.0005) and 358 dyne s cm(-5) (20 parts per million NO + dipyridamole) (p < 0.001 versus NO alone), and mean pulmonary artery pressure decreased from 29.0 to 20.5 (p < 0.0001) and 19.3 mm Hg (NS versus NO), respectively. Mean arterial pressure decreased from 85 to 74 mm Hg (dipyridamole + NO) (p < 0.01). High-dose dipyridamole (100 micro g/kg/min) with inhaled NO reduced pulmonary vascular resistance to 334 dyne s cm(-5) but also decreased mean arterial pressure to 57 mm Hg. Eight piglets developed rebound pulmonary hypertension. Two died of acute right ventricular failure and, in five, rebound pulmonary hypertension was prevented by low-dose dipyridamole. In conclusion, low-dose i.v. dipyridamole augments the effects of inhaled NO on right ventricular afterload with moderate changes in systemic hemodynamics, and can prevent rebound pulmonary hypertension.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMedDate not supplied

Scanning electron microscopic surface topography of ablation catheter perforations and calcific tear in an explanted bioprosthetic heart valve.

The authors report a triplet of leaflet destruction in a bioprosthetic aortic valve explanted at 12 years after iatrogenic ablation catheter perforation in a patient who underwent coronary artery bypass surgery and multiple ablative procedures in the interim. Lesions were examined topographically by scanning electron microscopy. Calcium content was evaluated by mass spectrometry and Von Kossa staining. Leaflets exhibited little calcification, except at the commissures of the valve. Scanning electron microscopy revealed distinct lesion topography. The authors present the scanning electron microscopic characteristics of these lesions and of an incision into the valve made for comparison using a pair of scissors. This is believed to be the first report of scanning electron micrographs of ablation catheter perforations and a calcific tear in the same explanted valve. The findings provide a source for comparison in the etiological determination of explanted bioprosthetic valve lesions using scanning electron microscopy.

Aged↗