Biomedical subjects

D Curnier

Publications and source records attributed to D Curnier.

6 recordsLinked to original sources

PubMed2003

Correlation between nucleus zone migration within scoliotic intervertebral discs and mechanical properties distribution within scoliotic vertebrae.

Correlations between intervertebral disc degeneration and bone mass were investigated previously, but never on scoliotic patients. Using MRI measurements of intervertebral discs behavior and vertebral bone tomodensitometry, correlations between nucleus zone displacement within intervertebral discs and mechanical center migration within vertebral bodies were investigated in vivo on scoliotic patients. The protocol, performed on eleven scoliotic girls, was composed of a CT scan acquisition of apical and adjacent vertebrae followed by a MRI acquisition of the thoracolumbar spine. The displacement between the vertebral body centroid and inertia center was computed from the CT images and called the mechanical migration. The displacement between nucleus zones and vertebral body centroids was quantified from MRI and called the nucleus zone migration. For apical vertebrae, a significant correlation was found in the coronal plane (r = 0.766, p < 0.01), but not in the sagittal plane (r = -0.349, p > 0.05). For adjacent vertebrae, significant correlations were found in both coronal (r = -0.633, p < 0.05) and sagittal (r = -0.797, p < 0.01) planes. The nucleus zone migration occurred in the convexity of the curvature whereas the mechanical migration occurred in the concavity.Known secondary mechanical phenomenon of scoliosis was quantified using new parameters describing intervertebral discs and vertebral bodies. Further investigations should be performed to explain the mechanical evolution of scoliosis and to use these parameters in predictive criteria of scoliosis.

Bone Density↗

PubMed2001

Intervertebral disc modeling using a MRI method: migration of the nucleus zone within scoliotic intervertebral discs.

MRI is increasingly being used for etiologic examination of scoliosis and for intervertebral disc disorder analysis, but until now has not been applied to geometric modeling. The aim of this study was to develop a new geometric model of intervertebral discs using MRI and to quantify the migration of the nucleus zone within scoliotic intervertebral discs. Fourteen lumbar scoliotic children (Cobb angles 22 +/- 7 degrees ) were examined using MRI. The protocol consisted of sagittal and coronal plane acquisitions of the entire spine. An image processing software allowed the outline detection of the nucleus zone (intervertebral high intensity portion). The vertebral bodies were also reconstructed. Using a pre-post processor, the nucleus zone migration and a wedging angle were quantified. Statistical tests showed the repeatability of the method (p > 0.4). Nucleus zone migration was correlated to the wedging angle (r(2) = 0.488, p < 0.0001) in the coronal plane. Our results were in agreement with the literature: when two vertebrae move deforming the disc, the nucleus moves into the convexity of the curvature. But should we talk about the nucleus? Despite image processing software allowing the highlighting of image features (automatic color lookup tables applied to grayscale images using pixel intensity measurements), it is impossible to differentiate the nucleus from the annulus on T2 weighting images of adolescent spine. This new geometric model of the intervertebral disc, used for the quantification of the nucleus zone migration, should be of interest for further investigation of stiffness parameters of spine.

Analysis of Variance↗

PubMed2001

Rehabilitation of patients with congestive heart failure with or without beta-blockade therapy.

BACKGROUND: Management of heart failure includes beta-blockade (betaB) therapy and cardiac rehabilitation. The aim of this study was to compare the exercise training response of patients with congestive heart failure (CHF) receiving betaB therapy with that of patients not receiving treatment. METHODS AND RESULTS: Thirty-four consecutive patients with CHF were included in a 4-week training program at their ventilatory threshold (VT); 6 patients received betaB treatment and 18 did not. The patients underwent a cardiopulmonary exercise test before and after training. Oxygen uptake (VO(2)) at peak exercise and at VT increased in both groups (P < or =.0001) without any significant differences between the groups. The same results were found after adjustment to ejection fraction and VO(2) at the start of the training program. There was no difference in VT improvement, measured as a percentage of utilization of maximal oxygen uptake, between the groups. After training, heart rate and ventilation decreased (P < or =.0001) at submaximal levels in both groups without significant differences between the groups. CONCLUSIONS: betaB therapy does not impair functional improvement induced by a rehabilitation program in patients with CHF. betaB therapy does not interfere with exercise training prescription if patient exercise evaluations are made at the time of therapeutic intake.

Adrenergic beta-Antagonists↗

PubMed2001

[Left ventricular hypertrophy and sinus variability in arterial hypertension].

BACKGROUND: Previous studies of heart rate variability (HRV) in systemic hypertension have yielded conflicting results. We sought to assess the alterations of HRV in hypertensive patients with or without left ventricular hypertrophy (LVH). METHODS: 195 hypertensive patients in sinus rhythm, mean age 53 +/- 11 years, without diabetes mellitus, nor symptomatic coronary disease or systolic dysfunction, were prospectively enrolled. Echocardiographic examination allowed their subdivision in 3 groups: normal geometry (112), concentric remodeling (43) and LVH (40). Time and frequency domain measures of HRV were obtained from 24 h Holter ECG recordings in all patients as in 40 control subjects. RESULTS: In comparison with control subjects, the 3 hypertensive groups presented a significant decrease of SDNN and total frequency power both indexes of global HRV; a significant decrease of pNN50 and high frequency power, indexes of HRV reflecting parasympathetic tone, and a significant decrease of SDANN and low frequency power, indexes reflecting sympathetic modulation of HRV. Comparisons among the three hypertensive groups showed that patients with LVH had significantly (p < 0.05) lower low frequency power (5.5 +/- 1.0 Ln m2) than patients with left ventricular normal geometry (5.9 +/- 0.8 Ln m2) or concentric remodeling (5.9 +/- 0.9 Ln m2). CONCLUSION: Assessment of HRV in hypertensive patients shows a constant decrease of parasympathetic indexes and a more markedly reduction of sympathetic parameters in presence of LVH.

Aged↗

PubMed2000

Depressed low frequency power of heart rate variability as an independent predictor of sudden death in chronic heart failure.

AIMS: Identification of patients with chronic heart failure at risk for sudden death remains difficult. We sought to assess the prognostic value for all-cause and sudden death of time and frequency domain measures of heart rate variability in chronic heart failure. METHODS AND RESULTS: We prospectively enrolled 190 patients with chronic heart failure in sinus rhythm, mean age 61+/-12 years, 109 (57.4%) in NYHA class II and 81 (42.6%) in classes III or IV, mean cardiothoracic ratio 57.6+/-6.4% and mean left ventricular ejection fraction 28.2+/-8.8%, 85 (45%) with ischaemic and 105 (55%) with idiopathic dilated cardiomyopathy. Time and frequency domain measures of heart rate variability were obtained from 24 h Holter ECG recordings, spectral measures were averaged for calculation of daytime (1000h-1900h) and night-time (2300h-0600h) values. During follow-up (22+/-18 months), 55 patients died, 21 of them suddenly and two presented with a syncopal spontaneous sustained ventricular tachycardia. In multivariate analysis, independent predictors for all-cause mortality were: ischaemic heart disease, cardiothoracic ratio > or =60% and standard deviation of all normal RR intervals <67 ms (RR = 2.5, 95% CI 1.5-4.2). Independent predictors of sudden death were: ischaemic heart disease and daytime low frequency power <3.3 ln (ms(2)) (RR = 2.8, 95% CI 1.2-8.6). CONCLUSION: Depressed heart rate variability has independent prognostic value in patients with chronic heart failure; spectral analysis identifies an increased risk for sudden death in these patients.

Arrhythmias, Cardiac↗

PubMed2000

[Utilization of heart rate at the ventilatory threshold for the prescription of intensity of exercise training in cardiac failure].

Physical exercise is a treatment for cardiac failure but a large range of intensities of exercise is proposed. The aims of this study were to determine the range of intensities of effort used and to individualize the intensities used. Thirty patients with stable cardiac failure (NYHA Classes II-III, age: 53 +/- 2.1 years, ejection fraction: 31 +/- 1.4%) underwent a cardiorespiratory exercise stress test before and after individualized training at the ventilatory threshold. However, before and after the training period, standard methods of calculation of the intensities at the ventilatory threshold showed individual differences greater than +/- 2 standard deviations, indicating different metabolic stimulations. After the individualized training programme, peak oxygen consumption on exercise (1679 +/- 100 vs 1487 +/- 89 ml.min-1, p = 0.0001) and at ventilatory threshold increased (1365 +/- 85 vs 1133 +/- 65 ml.min-1, p = 0.0001), the ventilatory threshold/peak exercise ratio increased (81.2 +/- 1.3 vs 76.7 +/- 1.4%, p = 0.0008), and there was a decrease in heart and ventilatory rates at submaximal metabolic levels (p = 0.0001). The authors conclude that protocols using intensity of effort at the ventilatory threshold give similar results with respect to improvement of aerobic capacity as other methods of indirect calculation, based on maximal heart rate of oxygen consumption. The value of this particular method lies in the adequation between aerobic capacity of the patient and the intensity of training. The results obtained attain the physiopathological aims of rehabilitation.

Calibration↗