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B Meyns

Publications and source records attributed to B Meyns.

At least 55 records · Page 3Linked to original sources
PubMed1997

Can the outcome of coronary bypass grafting be predicted reliably?

OBJECTIVE: To test prospectively the unsubstantiated claim that patient-specific predictions of time-related outcome after coronary artery bypass grafting (CABG) from multivariable parametric equations are reliable for medical decision making and for intra- and interdepartmental quality control in surgical training and practice. METHODS: 3720 survival curves were generated prospectively for all primary, isolated CABG patients operated upon at the Katholieke Universiteit (KU) Leuven between July, 1987 and January, 1992 using the published AHA/ACC guidelines multivariable equation derived from prior KU Leuven experience. The average of these curves (risk-adjusted predicted survival) was compared to the Kaplan-Meier (actual) estimates, overall and for patient subsets. Variables associated with systematic deviation of actual from predicted number of deaths were sought by multivariable residual risk analysis. RESULTS: Actual overall survival was less good than predicted (P = 0.03) and the excess risk was distributed uniformly across time. The excess risk was not attributable to substantial changes in prevalence of known risk factors. It was attributable largely to a small subset of patients (n = 292) with low-prevalence, but important risk factors not accounted for by the equation (P = 0.7, for difference in survival among the remaining 3428 patients). CONCLUSIONS: Within the confines of a single institution, patient-specific predictions of outcome after CABG can be made reliably in most patients using multivariable equations developed from a heterogeneous experience, despite changes in prevalence of risk factors. New subsets of high-risk patients, failure or inability to account for important rare risk factors or for institutional changes, may lead to systematic errors of prediction. Under these limitations it is an excellent tool for medical decision making and audit of surgical training and practice.

Adult↗
PubMed1997

Validation and interdependence with patient-variables of the influence of procedural variables on early and late survival after CABG. K.U. Leuven Coronary Surgery Program.

OBJECTIVE: First to identify the patient-, procedural- and surgical experience variables influencing the early and late survival after CABG. Second to identify patients likely to benefit, and those unlikely to benefit, from technical details aimed at improving the results of coronary artery bypass grafting (CABG). METHODS: A consecutive series of 9600 patients who underwent CABG using a variety of revascularization methods between 1971 and 1992 were followed with 99.9% success. A multivariable time-related analysis was performed. Patient-specific predictions and nomograms were constructed from it to explore and validate the influences and interdependences of patient-variables with variations in details of the procedure. RESULTS: The 1-, 10- and 20-year risk-unadjusted survival was 97, 81 and 50% respectively. Patient-variables influencing early survival included severity of symptoms, patient presentation and extent of coronary disease, while late survival was influenced importantly by left ventricular function and cardiac and non-cardiac comorbidity. Technical details of the operation influencing early survival included use of endarterectomy, while details such as use of arterial grafting, extensiveness of sequential grafting, completeness of revascularization and extent of grafting to small coronaries influenced late survival to a highly variable degree. CONCLUSION: The early survival is neither improved nor worsened by single, multiple, sequential or complete arterial coronary reconstruction. The late survival is modestly improved with the use of an arterial graft to a major vessel, preferably but not exclusively to the anterior descendens, except for patients with limited life-expectancy. Differences in time-related survival with and without an arterial graft are nearly the same across all levels of ejection fraction. No late beneficial or detrimental effect was identified with more extensive use of arterial reconstructive surgery in multisystem disease.

Adult↗
PubMed1997

Early and late outcome after CABG in patients with evolving myocardial infarction.

OBJECTIVE: To study the determinants of early and late outcome after coronary artery bypass grafting (CABG) for evolving myocardial infarction. METHOD: 269 consecutive patients underwent isolated primary or repeat CABG from 1971 to 1992 for evolving myocardial infarction. By institutional policy, these were patients, strictly diagnosed, infarcting either in the cardiac cateterization laboratory, shortly after a previous CABG, or on cardiac intervention waiting lists. At operation, 125 patients were hemodynamically stable, 89 patients in cardiogenic shock 55 patients in cardiopulmonary resuscitation (CPR). Interval between infarct onset and surgical reperfusion ranged from 53 min to 15 h (median, 135 min; 90% between 75 and 360). An internal mammary artery graft (IMA) was used in 81 patients. Cross-sectional follow-up was 100% complete and multivariable analysis was conducted in the hazard function domain. RESULT: One-month, 1-year and 10-year survival was 86, 84 and 66%, respectively. The 1-year and 10-year survival, stratified by hemodynamic class, was respectively 98 and 77% for the stable patients, 77 and 60% for the patients in shock and 62 and 49% for those undergoing CPR. Shock and CPR were incremental risk factors for early but not late risk. Use of an IMA graft was not a risk factor early or late in either stable or unstable patients. CONCLUSION: CABG can be performed with acceptable early and long-term risk in selected patients with evolving myocardial infarction, whatever their hemodynamic state. Outcome as regards survival is neither adversely or advantageously affected by choice of bypassing conduit. An evolving myocardial infarction with stable hemodynamics carries a lesser risk than an unstable anginal state with changing ST-segment.

Angina, Unstable↗
PubMed1997

The Bicarbon heart valve prosthesis: short-term results.

BACKGROUND AND AIMS OF THE STUDY: To determine the short-term results of the Bicarbon (Sorin Biomedica, Saluggia, Italy) heart valve prosthesis at our institution. METHODS: Between November 1991 and December 1995, 256 patients (mean age 59.9 +/- 9.8 years) underwent valve replacement with a Bicarbon valve prosthesis. The mean ejection fraction was 60 +/- 14.8% and the mean left ventricular end-diastolic pressure 15.9 +/- 8.7 mmHg. Redo (n = 61) and combined procedures (n = 72) were included in this study; mixed types of prostheses were excluded. The procedures were divided into groups: aortic valve replacement (n = 163), mitral valve replacement (n = 60) and aortic-mitral (double) valve replacement (n = 33). Kaplan-Meier survival analysis was performed and predictors for survival were tested univariately and multivariately. RESULTS: The mean follow up was 30 +/- 25.1 months with a total of 7,696 patient-months (641.3 patient-years) and was 100% complete. The Kaplan-Meier survival rate at 48 months was 87 +/- 2%. The valve-related morbidity expressed as linearized incidence rate (% per patient-year) was: anticoagulation bleeding 2.3 +/- 0.6; thromboembolic event 1.0 +/- 0.4; periprosthetic leak 0.6 +/- 0.3; and endocarditis 0.3 +/- 0.2. Univariate significant factors for worse survival were: higher preoperative New York Heart Association (NYHA) functional class, valve implantation site, presence of associated operation, increasing age, decreasing ejection fraction, longer aortic cross-clamp time, and longer cardiopulmonary bypass time. In multivariate analysis longer aortic cross-clamp time and higher preoperative NYHA classification were significant independent predictors. CONCLUSIONS: These good short-term results after Bicarbon valve replacement are encouraging and comparable with those obtained with other bileaflet mechanical heart valves. However, further follow up is mandatory.

Adult↗
PubMed1997

Pre-clinical evaluation of a novel, pneumatic, ventricular assist device (Medos HIA-VAD) under pathophysiological conditions.

To evaluate a new cardiac assist system, the Medos HIA-VAD, we studied the effects of mechanical unloading on regional and global myocardial dysfunction. As a model for the regional temporary contractile dysfunction we chose an anesthetized, open chest preparation in sheep. We occluded the diagonal coronary artery for 15 minutes and reperfused for 90 minutes. Hemodynamic parameters and wall thickening were monitored. Unloading with the 60-ml Medos HIA-VAD was performed either during ischemia (group II) or during reperfusion (group III). The recovery of non-uniformity indicated by post-ejection wall thickening was significantly faster (p < 0.05) in both groups if compared to the non-assisted group (group I) (all groups n = 4). Recovery of systolic wall thickening in the postischemic region in group I was only 76 +/- 12%, while it was 103 +/- 11% and 92 +/- 11% in groups II and III, respectively (p < 0.05). In a canine model of global left ventricular failure, we occluded the left anterior descending coronary artery for 20 min, and after 5 minutes of reperfusion, the circumflex artery for 45 min (group I, n = 5). After 5 min of CX occlusion in group II we performed assisted circulation for 90 min with the 10-ml (n = 5) and the 25-ml (n = 5) Medos HIA-VAD. In group I, no dog survived, in group II, all survived 4 hours of reperfusion (n = 10). Lactate at the end of the experiment was 1.1 +/- 0.9 mmol/L (10-ml, and 1.1 +/- 0.2 mmol/L (25-ml) (p > 0.05 vs. base line). We conclude that the Medos HIA-VAD is a reliable assist device that enhances myocardial recovery and allows sufficient peripheral circulation in the case of cardiogenic shock.

Animals↗
PubMed1997

Pulmonary artery aneurysm: is surgery always indicated?

The authors present a seventy-eight year old woman with an aneurysm of the main pulmonary artery. Although a surgical approach is generally considered life-saving by preventing rupture of the aneurysm, literature is unclear about possible rupture in the specific situation of a pulmonary artery aneurysm without a causative cardiac lesion and/or pulmonary hypertension. In fact, some reports suggest a conservative treatment for this specific entity. Therefore we did not operate on our patient and she remains stable at 18 months follow-up.

Aged↗
PubMed1996

Effects of failure of the right side of the heart and increased pulmonary resistance on mechanical circulatory support with use of the miniaturized HIA-VAD displacement pump system.

This experimental study was designed to assess the influence of failure of the right side of the heart or pulmonary hypertension, or both, on the performance of a novel miniaturized left ventricular assist device. In small-sized dogs (n = 50) ischemic global left ventricular failure was induced and support was provided by the HIA-VAD displacement pump (stroke volume 10 or 25 ml) installed as a left ventricular assist device. In three groups of animals (n = 10 each) pulmonary hypertension was created before induction of global left ventricular failure. During left ventricular assist device support temporary ischemic failure of the right side of the heart was induced in four groups of animals (n = 10 each). In the group subjected to left ventricular failure, support with the left ventricular assist device, and right ventricular failure during left ventricular assist, left atrial pressure and cardiac index were significantly lower than in the group subjected to left ventricular failure and left ventricular assist alone (2 +/- 6 versus 11 +/- 6 mm Hg and 1.6 +/- 0.4 versus 1.0 +/- 0.4 L/(min/m2), respectively, p < 0.05). In the group subjected to pulmonary hypertension, left ventricular failure, and left ventricular support, left atrial pressure dropped to values near zero but cardiac index remained unaltered as compared with results with the same regimen without pulmonary hypertension. However, when right ventricular failure was added (that is, pulmonary hypertension, left ventricular failure, left ventricular support, and right ventricular failure during support with the left ventricular assist device) left atrial pressure dropped to negative values (p < 0.05) and cardiac index progressively deteriorated. When, in an additional group of dogs, biventricular support was installed in the latter regimen, circulation was initially well supported but oxygenation deteriorated in 60% of cases. We conclude that (1) adequate right ventricular function was indispensable during support with the left ventricular assist device, (2) the combination of pulmonary hypertension and right ventricular failure led to the "low left ventricular assist device output syndrome," and (3) biventricular mechanical support in the presence of pulmonary hypertension may be complicated by the alveolar leakage syndrome.

Animals↗
PubMed1996

Rhythm disturbances after mitral valve surgery: comparison between left atrial and extended trans-septal approach.

This study was undertaken to determine the incidence of postoperative arrhythmias in mitral valve surgery through the left atrium as compared with the extended trans-septal approach. All patients undergoing mitral valve surgery for acquired valve disease between 1 January 1991 and 31 December 1993 were reviewed. Only patients with preoperative normal sinus rhythm were included in this study. End-points for analysis were: 'any supraventricular arrhythmia'; 'atrial fibrillation of flutter'; and 'ectopic atrial or junctional rhythm'. All predictive factors with a P-value < 0.10 in univariate analysis were entered into the multivariate proportional hazard model of Cox. Some 72 patients were included for analysis. No variables were independently predictive of 'any supraventricular arrhythmia'. Age is an independent predictor of 'atrial fibrillation or flutter' and surgical approach of 'ectopic atrial or junctional rhythm'.

Adult↗
PubMed1996

The heart-Hemopump interaction: a study of Hemopump flow as a function of cardiac activity.

The Hemopump is a useful left ventricular assist device. Because it is a rotary blood pump, the pump performance is not constant and is dependent on the cardiac cycle. We measured the static flow delivered by the pump at varying pressure heads (delta P) in a mock circulation. These data are compared to the pump performance in vivo. On the basis of these results, 5 sheep were instrumented for continuous Hemopump flow measurement as well as left ventricular and aortic pressure measurements. The Hemopump flow was relayed instantaneously to the pressure head. Low filling and ventricular failing (through intravenous administration of a beta-blocker) conditions were applied. The in vivo measured flows also are pressure head dependent, but the flow curve shows hysteresis resulting in a loop during each cardiac cycle. The in vivo peak flows (delta P = 0) are similar to the in vitro data. The in vivo means flows (delta = 50 mm Hg) are similar to the in vitro data for the lower pump speeds but are less than that at the higher pump speeds (3.74 +/- 0.55 L/min in vivo at Speed 7 versus 4.6 L/min in vitro). Low filling interrupts the delta P-flow loop and reduces flow. In the failing ventricle, delta P increases and flow is reduced. The cannula leaks and results in aortic insufficiency (0.36 +/- 0.05 L/min) when the pump is turned off. Several conclusions have been drawn from these tests: Cardiac activity is beneficial for the pump performance as well as when the aortic pressure curve is nonpulsatile; the longer the systolic phase, the higher the pump flow; the pump should never be turned off in clinical use, and filling is important for the pump's performance.

Animals↗
PubMed1996

Hemodynamic system analysis of intraarterial microaxial pumps in vitro and in vivo.

Because of the lack of a sophisticated pump management system, the performance of the Hemopump in patients cannot assessed successfully. To clarify the interrelationship between an intravascular nonpulsatile pump and a pulsating ventricle, an in vitro study was set up under controlled conditions. Before these in vitro experiments, a series of in vivo experiments were performed in sheep using Hp31 cannulae. As anticipated, the resulting pulsatile pump flow was a function of the momentary pressure difference across the pump. This varying pump flow showed a significant flow loop hysteresis, indicating that the pressure difference across the pump is not the only parameter governing momentary pump flow of a rotary pump operating at constant speed in a pulsatile environment. Furthermore, flow in the Hp31 was significantly influenced by the inflow situation, blood supply, size of the ventricular cavity, and shape and position of the inflow cannula within the ventricle. Pulsatile flow conditions with good as well as impaired inflow into the pump were accordingly simulated in vitro to verify the in vivo measurements, to characterize the various inflow conditions, and to discuss methods of improved pump management. As a result of the in vivo and in vitro experiments, one can rely on the measurement of nonpulsatile in vitro flow and pressure differences across the pump to characterize the momentary pump flow for good inflow conditions into the pump. For these situations, the flow hysteresis produced, caused by fluid inertia within the pump and cannula, can be neglected. In contrast, for an impaired inflow situation, the calculated pump flow based on pressure difference measurements can be misleading. Consequently, an improved pump management system is required to adjust the pump speed, the pump performance, to any kind of impaired inflow.

Animals↗
PubMed1995

Left-ventricular unloading with a new pulsatile assist device: the HIA-VAD system and its influence on myocardial stunning.

To assess the mechanical unloading properties of a new pneumatic cardiac assist device (60 ml Medos HIA-VAD) and its possible influence on recovery from myocardial stunning we performed a study in 12 anaesthetized sheep. After left thoracotomy measuring transducers were placed and the assist device connected between the left-atrial appendage and the descending thoracic aorta. Global hemodynamics were measured before and after unloading was performed. Myocardial stunning was induced by transient occlusion of a coronary artery for 15 minutes and regional myocardial wall thickening was measured. A group without unloading served as controls (group I, n = 4). In a second group unloading was performed during the last ten minutes of ischemia (group II, n = 4) and in a third group unloading was performed for 30 minutes starting after ten minutes of reperfusion (group III, n = 4). After starting the Medos HIA-VAD, significant unloading could be demonstrated: left-ventricular dP/dtmax decreased significantly (p < 0.05) to 54% and 61% in groups II and III and left-atrial pressure to 50% and 71%, respectively. Systolic and mean arterial pressure did not change significantly (p > 0.05), while the diastolic pressure increased (p < 0.05) to 134% and 138% in groups II and III. After mechanical unloading whether during ischemia or during reperfusion systolic wall thickening in the postischemic area recovered to 103% and 92% of preischemic control in groups II and III, respectively. Recovery was incomplete in the non-unloaded controls (76%) (p < 0.05 versus groups II and III). Post-ejection thickening, a diastolic measure of stunning, diminished significantly after unloading in both protocols (p < 0.05 for groups II and III versus group I). We conclude that mechanical unloading with the 60 ml Medos HIA-VAD significantly improves recovery from myocardial stunning.

Animals↗
PubMed1995

Mechanical unloading properties of axial flow pumps and their effect on myocardial stunning.

Postischemic myocardial dysfunction affects morbidity and mortality in patients with coronary artery disease. It is known that mechanical unloading of the left heart ventricle can positively influence postischemic myocardial dysfunction. In this respect we tested two miniaturised axial flow pumps, i.e. the 14-F and the 21-F Hemopump. An experimental study was carried out on 30 open chest sheep where regional myocardial wall motion was followed using sonomicrometry in a preparation of transient coronary artery occlusion. Only the larger 21-F Hemopump showed hemodynamically significant unloading of the left ventricle. Furthermore, as far as stunning is concerned, systolic wall thickening recovered better when this type of pump was used during reperfusion. Also postejection thickening, which is an indication of diastolic postischemic dysfunction, is reduced significantly in the postischemic area (ANOVA, p < 0.05). Thus, the 21F Hemopump, but not the 14F Hemopump, provides adequate mechanical unloading in order to beneficially influence myocardial stunning.

Analysis of Variance↗
PubMed1994

Cardiac transplantation in giant cell myocarditis. A case report.

The present report describes a 15-year-old boy who underwent an urgent cardiac transplantation for giant cell myocarditis because of fulminant progressive heart failure, complicated by ventricular tachycardia, unresponsive to classical inotropic medical treatment. The physiopathology and the treatment are discussed.

Adolescent↗
PubMed1994

Aortic and mitral valve replacement with the Carpentier-Edwards pericardial bioprosthesis: mid-term clinical results.

Between May 1st 1985 and December 31st 1992, 283 Carpentier-Edwards pericardial valves were implanted in 260 patients in the aortic (n = 196), mitral (n = 41) and both aortic and mitral (n = 23) positions at the Gasthuisberg University Hospital in Leuven, Belgium. Patients undergoing tricuspid valve replacement or mixed replacement with another type of prosthesis were excluded from this study. The mean age was 70 +/- 7 years, there were 121 males and 139 females. The mean follow up was 40.55 months, the total follow up experience 10543 months (878.6 patients years). Hospital mortality was 10.4%, and was not significantly related to the position of the valve: 17.3% +/- 7.88% (n = 23) for double valve replacement, 10.2% +/- 2.16% (n = 196) for aortic valve replacement and 7.3% +/- 4.06% (n = 41) for mitral valve replacement. Hospital mortality was 14.1% +/- 3.27% for those with and 7.48% +/- 2.5% for those without concomitant coronary surgery (p = NS). Survival at 92 months was 63% +/- 6% and was not significantly related to the position of the valve. Not a single patient needed to be reoperated because of primary tissue failure. We conclude that the mid-term durability of this valve is excellent and consider the Carpentier-Edwards pericardial valve as the stented bioprosthesis of choice both in the aortic and mitral positions for the elderly. Because of the older age of our study population and the medium term length of follow up, we were unable to draw any conclusions concerning the incidence of calcific degeneration of this valve.

Adult↗
PubMed1993

Surgery for cardiac myxoma. A 20-year experience with long-term follow-up.

Data on 32 consecutive patients undergoing resection of a cardiac myxoma over a 20-year period (1971-1991) was analyzed. The mean age of the patients was 57 +/- 11 years (range 36 to 78). All myxomas were located in the left atrium except one right ventricular tumor. Ten of the atrial resections were performed with only an endocardial cuff while a full thickness atrial septum cuff was removed in 21 cases. One patient, operated under emergency conditions, died 11 days later as a result of cardiac and pulmonary failure (hospital mortality 3.1%). Late follow-up (mean 6.4 +/- 4.4 years) shows excellent results. All patients are alive and well. No recurrences have been found. In this series, good long-term results were obtained by simple excision of cardiac myxomas. This finding supports the theory that recurrence is mainly confined to patients with familial presentation and/or myxoma complex.

Adult↗
PubMed1992

Time course of serum lipid and lipoprotein levels after coronary bypass surgery: modification by pravastatin.

The time course of the changes in serum lipid and lipoprotein levels have been studied in 100 patients undergoing coronary artery bypass surgery. Marked decreases occur in the levels of cholesterol (-45%), HDL-cholesterol (-35%), LDL-cholesterol (-53%), Apo A1 (-43%) and Apo B (-43%) on the third day after the operation. In the control group the values gradually returned to preoperative levels which are reached after three months. Three months after the intervention, in the pravastatin-treated group (20 mg/day) the values of total cholesterol (-20%), LDL-cholesterol (-28%) and Apo B (-22%), remained significantly lower than in the control group (p 0.0001) and were lower over the whole duration of the study. The postoperative time course of HDL-cholesterol and Apo A1, however, was not significantly influenced by the administration of pravastatin.

Aged↗