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J Roelandt

Publications and source records attributed to J Roelandt.

At least 19 recordsLinked to original sources
PubMed2003

[Aetiologies of lithium overdose: 10-year experience of Marseille poison centre].

OBJECTIVE: Lithium is used for control of bipolar disorders. In order to precise the different circumstances at the origin of poisonings, the authors present the cases of lithium intoxication observed in the Marseille poison centre between January 1991 and December 2000. STUDY DESIGN: Retrospective study. METHODS: Three hundred and four cases were observed during the studied period (1 patient a case), concerning 6 different circumstances. For 3 of them, the symptoms were mild: accidental ingestion with children (13 cases); mistakes on the quantities of ingested tablets (43 cases); elevation of lithium blood level due to diuretic therapy (8 cases). For 2 other circumstances, the clinical signs were more severe: treated patients who developed renal failure (15 cases, 6 patients managed in intensive care unit [ICU], 1 death) or dehydration (35 cases, 8 patients treated in ICU and 1 death). Finally, the most severe cases were collected with suicide attempts. Fifty-six percent of the patients were managed in ICU, 5% needed haemodialysis, 10% had cardiac (repolarization disturbances) or neurological (seizures) complications, 2% died. CONCLUSION: The severity of lithium poisonings depends of the circumstances. Ingestion of high quantities of sustained released tablets is the most dangerous situation. Accidental ingestion, even with children, must be considered as less severe situations.

Accidents↗
PubMed1997

Influence of heart rate, respiration and recipient atrial contraction on pulsed wave transmitral Doppler flow indices in orthotopic heart transplant recipients.

AIMS: The study set out to assess the relative contributions of donor heart rate, respiration and recipient atrial contraction on the mean of pulsed wave transmitral Doppler flow indices in orthotopic heart transplant recipients. This would provide information on the theoretical usefulness of pacemaker synchronization of recipient atrial contraction, as well as on the validity of certain strategies used for pulsed wave Dopper analysis of diastolic left ventricular function, which have excluded beats based on recipient atrial contraction timing. METHODS: Thirty two consecutive patients undergoing orthotopic heart transplantation in our centre were prospectively studied. The following Doppler indices were analysed: peak early diastolic velocity (E) and its area under the Doppler curve (TVIE), diastolic velocity after donor atrial contraction (A) and its area under the curve (TVIA), the total area under the curve (TVI), the isovolumic relaxation period (IVR), the diastolic filling period, the normalized peak filling rate and the pressure half time. RESULTS: Only 81 out of 347 recordings (23%) allowed analysis of the recipient P wave and thus recipient atrial contraction timing, heart rate and the respiration phase in 22 patients for a total of 1579 beats. The isovolumic relaxation period, E, pressure half time and TVIA are not influenced by donor heart rate. For the isovolumic relaxation period, E, TVI and TVIE, respiration contributes as much as recipient atrial contraction timing to beat-to-beat variation. Pressure half time, the diastolic filling period and peak filling rate were not affected by respiration. TVI was not affected by recipient atrial contraction timing. CONCLUSION: With respect to analysis of diastolic function, exclusion of beats based on recipient atrial contraction timing is invalid for the isovolumic relaxation period. E, TVI and TVIE, since these are equally influenced by respiration. Since TVI was not affected by recipient atrial contraction timing, pacemaker synchronization of donor and recipient atria is not expected to be useful in patients with left ventricular diastolic dysfunction.

Atrial Function↗
PubMed1995

Precordial three-dimensional echocardiography with a rotational imaging probe: methods and initial clinical experience.

We report our initial experience with a precordial hand-held transducer assembly allowing computer controlled acquisition of cardiac images for dynamic three-dimensional tissue reconstruction in adult patients. A commercially available transducer and imaging system were used and its video output interfaced with the three-dimensional reconstruction unit. For this feasibility study, 20 patients in sinus rhythm and with good image quality were examined. The dynamic motion of the valves and ventricles was visualized in three-dimensional formats as well as relationships of complex pathology. Although the acquisition time in patients in sinus rhythm is relatively short, the reconstruction time is still too long and requires an experienced and dedicated operator. However, with further developments in computer technology dynamic three-dimensional echocardiography will undoubtedly become an integral if not the principal part of our routine echocardiographic examination in the future.

Adult↗
PubMed1994

[Dynamic transthoracic and transesophageal tridimensional echocardiography using rotational technique. A new perspective in echocardiography].

BACKGROUND: For many years, there has been a long-standing interest in developing three-dimensional echocardiography and several approaches have been followed. However, the main interest has been centered on reconstruction of left ventricular cavity. So far, dynamic three-dimensional representation of cardiac structures has been rather disappointing. OBJECTIVES: In this study, we describe the clinical application of dynamic three-dimensional echocardiography with a rotational imaging acquisition. METHODS: Three-dimensional echocardiography was performed in 50 patients referred to the Echocardiographic Laboratory at the Thoraxcenter for routine standard two-dimensional echocardiography (multiplane transesophageal = 30 patients; transthoracic = 20 patients) for different reasons. For transthoracic echocardiography, patients with good quality images were selected. We used prototype ultrasound probes connected to commercially available echocardiographic equipments interfaced to the Echo-Scan system. The steering logic of the system controlled the image acquisition in a given plane, at a predetermined moment in the respiratory and heart cycles (respiratory and ECG gating). Ninety rotational (2 degree interval) sector images of the heart were collected. The images were digitized, reformatted and interpolated, yielding a three-dimensional data set. From this data set, any desired cross-section of the heart could be computed, volume rendered and displayed in motion. Different algorithms were applied and mixed to produce a shaded dynamic three-dimensional display of cardiac anatomy. RESULTS: Acquisition of images and three-dimensional reconstructions were possible in all the patients. Both conventional and unusual projections were displayed. Thus, we were able to represent the cardiac structures from cutting planes which could not be visualized from standard transthoracic or transesophageal approaches. In particular, in patients with mitral valve prolapse and mitral stenosis the left atrial "surgical" view on the valve provided additional information on both site and extent of leaflets pathology. The presence and the degree of systolic anterior movement were seen in all the patients with hypertrophic cardiomyopathy and outflow obstruction, and the site of the leaflet involved identified. CONCLUSIONS: Dynamic three-dimensional echocardiography is clinically feasible and has the potential to offer information unavailable with conventional two-dimensional echocardiography. Rotational scanning is the logical extension of multiplane transesophageal probe, and circumvents the limitations due to the small acoustic windows during precordial acquisition.

Algorithms↗
PubMed1993

Ultrasound myocardial integrated backscatter signal processing: frequency domain versus time domain.

In the literature, different forms of measuring the ultrasound power returned by myocardial tissue are reported. Frequency domain methods will give the maximum frequency information, whereas time domain methods are limited in bandwidth, but more practical to realize. It was the purpose of this study to compare the various methods of signal processing. High frequency ultrasound signals from a pig's myocardium, digitally recorded during normal contractile performance, were analyzed by six different methods of signal processing to obtain estimates of backscatter power. The myocardial tissue characterization parameters studied were the integrated power as well as its cyclic variation during the cardiac cycle. A total number of 8109 ultrasound traces obtained in 16 pigs were processed. The study included three signal processing methods in the frequency domain: frequency compensated integrated backscatter calculated over both a large (4 MHz, method 1) as well as a small frequency bandwidth (2 MHz, method 2) and uncompensated integrated backscatter (method 3), and three methods in the time domain: high frequency signal squared and integrated (method 4), mean rectified signal level (method 5) and mean signal level after logarithmic compression and envelope detection (method 6). The random measurement variation (including beat-to-beat variation) was analyzed as well as the paired differences of the backscatter parameters obtained by the respective methods as compared with the only theoretically correct method in the time domain (method 4). The magnitudes of the random measurement variation expressed as a standard deviation (SD) were comparable (range 0.93-1.2 dB) except for method 6 (0.61 dB), where the measurement variation is decreased by the logarithmic compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Instantaneous pressure-velocity relationship of the coronary flow, alternative to coronary reserve measurement: a feasibility study and reproducibility of the method].

Animal experimentation has shown that the instantaneous pressure-velocity of coronary blood flow in the hyperaemic phase has a linear relationship. The slope of this regression evaluates coronary reserve independently of haemodynamic variables and the X-intercept (zero flow pressure or Pf = 0) determines the intra-myocardial back pressure which could influence the regulation of coronary flow. The object of this study was to evaluate the instantaneous pressure-velocity relationship of coronary flow in clinical practice and to analyse the reproducibility of this parameter. Forty-nine patients were divided into two groups, depending on whether their coronary arteries were angiographically normal (n = 34) or atheromatous with stenosis > or = 35% of the reference diameter (n = 15). Recordings of coronary flow velocity were made with a Doppler transducer mounted on a 0.018 inch guide wire. The slope of the diastolic linear segment of the pressure-velocity relationship was determined at the peak of papaverine-induced vasodilation from 4 consecutive cycles by a regression analysis. The pressure value at 0 flow was obtained by extrapolation of the regression slope to the axis of aortic perfusion pressure. A good quality spectral recording allowing reliable analysis of the velocity profile was obtained in 88% of cases (44/49). The high values of the correlation coefficient observed with each measurement of the slope confirm the applicability of linear regression analysis to the pressure-velocity relationship. The slope of the pressure-velocity relationship was significantly lower in patients with coronary stenosis (1.7 +/- 0.7 cm/s/mmHg in normal vessels versus 0.7 +/- 0.3 cm/s/mmHg in stenotic arteries, p < 10(-4)), and, similarly, the pressure at zero flow was also reduced (36.9 +/- 16 mmHg versus 25.5 +/- 12 mmHg, p = 0.03). A statistically significant correlation was observed between the slope values and coronary flow reserve but no correlation was demonstrated between the slope and intraluminal surface area of angiographically normal coronary arteries or the slope and degree of stenosis of atheromatous vessels. The linear regression slope and the pressure at zero flow were lower when the pressure-velocity relationship was measured during long diastolic periods induced by the injection of adenosine. In addition, the curvilinear appearances of the pressure-velocity relationship observed during these long periods suggest that the linear regression model is not applicable throughout the whole range of pressures and velocities, especially for the lowest values.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1992

Restenosis after coronary angioplasty: the paradox of increased lumen diameter and restenosis.

Restenosis after coronary angioplasty is the single complication that most limits this revascularization procedure in clinical practice. The process is largely unpredictable and the lesion-related factors predisposing to restenosis are poorly understood, with little consensus in published reports. In this study using detailed quantitative angiographic measurements to assess 490 lesions, the simple lesion characteristics associated with restenosis were defined and the relation to the restenosis process documented. Restenosis was defined as an absolute deterioration in the minimal lumen diameter by greater than or equal to 0.72 mm, a criterion based on the 95% confidence intervals for repeat angiographic measurements. This was chosen in an attempt to separate spurious changes due to a poor angiographic result and the variability of angiographic measurements from significant changes due to the restenosis process. The principal determinants of restenosis were found to be a large improvement in the minimal lumen diameter at the time of dilation (1.13 mm for the restenosis group compared with 0.86 mm for the no restenosis group [p less than 0.0001]) and an optimal postangioplasty result (minimal lumen diameter 2.28 mm in the restenosis group compared with 2.05 mm [p less than 0.001] in the no restenosis group, corresponding to a 25% and a 30% diameter stenosis, respectively [p less than 0.0001]). These observations reported for the first time suggest that the distinction needs to be made between a "clinical restenosis" of greater than or equal to 50% diameter stenosis and the "restenosis process" as measured by the absolute changes occurring during and after angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1992

Does the measurement of left ventricular isovolumic relaxation time allow early prediction of cardiac allograft rejection?

In order to evaluate the value of isovolumic relaxation time measurement for the diagnosis of moderate acute rejection episodes in cardiac allograft recipients a comparison was made with the histological results from the endomyocardial biopsy. A total of 202 isovolumic relaxation time measurements from 26 patients were compared to the biopsy results. The technique used to record isovolumic relaxation time was dual M-mode echocardiography. In addition a combined phonoechocardiography was used for 54 isovolumic relaxation time measurements from 17 patients. A good correlation was found between these two methods. When the biopsy results were normal the isovolumic relaxation time was 71.4 +/- 15.1 ms. When moderate acute rejection episodes were present isovolumic relaxation time decreased to 50.2 +/- 21.2 ms (p < 0.001). In spite of the close correlation detected at group level, there was a large variability of the measurements without accompanying changes in the biopsy specimen. At the same time a significant overlap was found between the measurements taken during rejection and non-rejection periods making it impossible to use these methods for clinical decision making. We conclude that isovolumic relaxation time measured with these methods is not a sufficiently sensitive parameter for the diagnosis of moderate acute rejection episodes in the individual patient, and in our experience, it is not a substitute for endomyocardial biopsy and can not be applied for clinical decision making.

Adolescent↗
PubMed1991

Does intravenous milrinone have a direct effect on diastolic function?

Bipyridine derivatives have recently been introduced as a new class of inodilator drugs in the intravenous therapy of heart failure. A member of this class is milrinone, which improves the inotropic state and reduces ventricular afterload, leading to improved hemodynamics. Because systolic and diastolic function are intimately related, it can be expected that the diastolic muscle properties are influenced by changes in systolic function and therefore by milrinone therapy. Since end-diastolic pressure may shift as a result of a change in ventricular volume alone, a complete left ventricular diastolic pressure volume (LVDPV) relationship must always be measured before one can make firm conclusions regarding changes in diastolic function. After a LVDPV relationship is obtained, one should identify the variables that can modify this relationship without directly affecting the intrinsic diastolic muscle properties. These variables can be divided into static effects (coronary vascular bed volume, right ventricular pressure, and pericardial pressure) and dynamic effects (viscoelasticity and myocardial active relaxation). Increments in coronary perfusion pressure of perfusion flow (vascular bed volume) are known to stiffen the cardiac wall (turgor effect). Changes in right ventricular pressure or pericardial pressure are other factors affecting the LVDPV relationship by changing transmural pressure. This effect is more pronounced when the ventricle is already stiff, such as in patients with myocardial hypertrophy. Dynamic effects become important when a LVDPV relationship is measured during isolated cardiac cycles; they include viscoelasticity and abnormal myocardial relaxation. Clinical assessment of diastolic cardiac performance assumes a model in which the heart is considered an elastic body (while in fact it is viscoelastic).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiotonic Agents↗
PubMed1991

The relative contributions of myocardial wall thickness and ischemia to ultrasonic myocardial integrated backscatter during experimental ischemia.

The purpose of this study was to assess the empirical relationship between myocardial integrated backscatter (IB) and myocardial wall thickness (WT) in normal myocardium. A second object was to estimate the additional contribution to acute ischemic integrated backscatter levels given this relationship. Myocardial IB measurements and simultaneous myocardial WT measurements were made in 16 open-chested pigs with intact coronary circulation (normal myocardium) and 10 min after the flow in the left anterior descending coronary artery had been reduced to 20% of its baseline value (ischemic myocardium). Measurements were made 50 times during one cardiac cycle and averaged over 10 cardiac cycles. IB and WT measurements were normalized with respect to the nonischemic end-diastolic values. The relationship between IB and WT in normal myocardium was estimated in every individual pig by simple linear regression. Estimates of IB during ischemia were calculated on the basis of this relationship and the ischemic WT measurements. Differences of the estimator and the actual measurement made during ischemia depict the actual contribution of the state of acute ischemia, without the influence of WT. The slope of the relationship between IB and WT during normal myocardial contraction ranged from -0.16 to 0.03 dB/% (mean = -0.036 dB/%, SD = 0.06 dB/%). The additional contribution of ischemia ranged from -3.84 to 5.56 dB (mean = 0.31 dB, SD = 2.72 dB). It was concluded that the average contribution of ischemia to IB measurements is insignificant if the IB dependency on WT is removed from the data and that the higher level of ischemic IB measurements can be explained by the decrease in wall thickness during ischemia and not by the ischemia itself.

Animals↗
PubMed1991

Quantitative angiography after directional coronary atherectomy.

OBJECTIVE: To assess by quantitative analysis the immediate angiographic results of directional coronary atherectomy. To compare the effects of successful atherectomy with those of successful balloon dilatation in a series of patients with matched lesions. DESIGN: Case series. SETTING: Tertiary referral centre. PATIENTS: 62 patients in whom directional coronary atherectomy was attempted between 7 September 1989 and 31 December 1990. INTERVENTIONS: Directional coronary atherectomy. MAIN OUTCOME MEASURES: Increase in minimal luminal diameter of coronary artery segment. RESULTS: Angiographic success on the basis of intention to treat was obtained in 54 patients (87%). In four patients the lesion could not be crossed by the atherectomy device; all four had an uneventful conventional balloon angioplasty. Four of the 58 patients who underwent atherectomy were subsequently referred for coronary bypass surgery because of failure or complications; three of them sustained a transmural infarction. In the successful cases, coronary atherectomy resulted in an increase in the minimal luminal diameter from 1.1 mm to 2.5 mm with a concomitant decrease of the diameter stenosis from 62% to 22%. In the subset of 37 patients in which the changes induced were compared with conventional balloon angioplasty atherectomy increased the minimal luminal diameter more than balloon angioplasty (1.6 v 0.8 mm; p less than 0.0001). Conventional histology showed media or adventitia in 26% of the atherectomy specimens. In hospital complications occurred in six patients who had undergone a successful procedure: two transmural infarctions, two subendocardial infarctions, one transient ischaemia attack, and one death due to delayed rupture of the atherectomised vessel. All patients were clinically evaluated at one and six months. One patient had persisting angina (New York Heart Association class II), one patient sustained a myocardial infarction, one patient underwent a percutaneous transluminal coronary angioplasty for early restenosis, and one patient underwent coronary bypass surgery because of a coronary aneurysm formation. At six months 80% (36/47) of the patients were symptom free. CONCLUSIONS: Coronary atherectomy achieved a better immediate angiographic result than balloon angioplasty; however, in view of the complication rate in this preliminary series, which may be related to a learning curve, a randomised study is needed to show whether this procedure is as safe as a conventional balloon angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1990

Recovery of regional myocardial dysfunction after successful coronary angioplasty early after a non-Q wave myocardial infarction.

More aggressive therapy has been suggested for patients who have a non-Q wave myocardial infarction (MI) because of the frequency of subsequent unstable angina, recurrent MI, and high mortality rate compared to patients with Q wave MI. The present study was undertaken to investigate the effect of coronary angioplasty on regional myocardial function of the infarct zone in patients with angina early after a non-Q wave MI. The study population consisted of 36 patients undergoing successful coronary angioplasty within 30 days of a non-Q wave MI, in whom sequential left ventricular angiograms of adequate quality were obtained before the initial procedure and at follow-up angiography. The global ejection fraction increased significantly from 60 +/- 9% to 67 +/- 6% (p = 0.0003). This significant increase in the global ejection fraction was primarily due to a significant improvement in the regional myocardial function of the infarct zone. The results of the present study show not only that ischemic attacks early after a non-Q wave MI may lead to prolonged regional myocardial dysfunction but more important that this depressed myocardium has the potential to achieve normal contraction after successful coronary angioplasty.

Angiography↗
PubMed1990

Ultrasonic myocardial integrated backscatter and myocardial wall thickness in animal experiments.

The purpose of this study was to distinguish between normal and ischemic myocardium using ultrasonic integrated backscatter (IB) measurements and to relate IB with myocardial wall thickness. IB was measured in 9 open-chested Yorkshire pigs (24-30 kg) before, after 30 minutes of partial occlusion of the proximal left anterior descending coronary artery (LADCA), and after 60 minutes of subsequent reperfusion. The ultrasound transducer (4 MHz) was sutured onto the epicardial surface perfused by the LADCA. IB measurements were made with a repetition rate of 50 times per heart rate simultaneously with a left ventricular pressure signal. Myocardial wall thickness was measured off-line. The measurements of integrated backscatter, left ventricular pressure and wall thickness were based on mean values of ten subsequent cardiac cycles. End-systolic IB measurements were 5.3 dB higher during occlusion as compared to the reference measurements (7.1 +/- 3.2 dB versus 1.8 +/- 2.6 dB; p = 0.002). No statistically significant differences were found in end-systolic IB measurements. End-systolic wall thickness was 5 mm smaller during occlusion as compared to the reference measurements (7.2 +/- 1.4 mm versus 12.2 +/- 1.2 mm; p less than 0.001). Simple linear regression analysis showed a statistically significant inverse relationship between IB measurements and wall thickness in 21 out of the 23 sequences in which wall thickness could be measured. End-systolic IB measurements are favourable to distinguish acute ischemic myocardium from normal myocardium. There is a distinct inverse relationship between IB and myocardial wall thickness.

Animals↗