Biomedical subjects
Publications and source records attributed to J Victor.
The effect of dual-chamber detected atrioventricular pacing mode alone and combined with rate-drop response reduced vasodepression and cerebral hypoperfusion induced by carotid massage in patients with carotid sinus syndrome.
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OBJECTIVES: To evaluate the long-term functional and hemodynamic effects of right ventricular outflow tract (RVOT) pacing by comparison with right ventricular apical (RVA) pacing. BACKGROUND: Acute studies have suggested that RVOT pacing could significantly improve cardiac performance in comparison with RVA pacing but no data are available in chronically implanted patients. METHODS: Sixteen patients with chronic atrial tachyarrhythmia and complete AV block were included. Left ventricular ejection fraction (LVEF) was > or =40% in ten and <40% in six. Patients were implanted with a standard DDDR pacemaker connected to two ventricular leads. A screw-in lead was placed at the RVOT and connected to the atrial port. A second lead was positioned at the RVA and connected to the ventricular port. Right ventricular outflow tract and RVA pacing was achieved by programming either the AAIR or the VVIR mode respectively. Four months later patients were randomized so as to undergo either RVOT or RVA pacing for three months according to a blind crossover protocol. Apart from the pacing mode, programming remained unchanged throughout the study. At the end of each period, NYHA class, LVEF, exercise time and maximal oxygen uptake were assessed. RESULTS: No significant difference was observed between the two modes for all the parameters analyzed. These identical results were observed in all patients globally, in patients with LVEF > or =40% as in those with LVEF <40%. CONCLUSIONS: Within the limits of this study, no symptomatic improvement or hemodynamic benefit was noted after three months of RVOT pacing, by comparison with RVA pacing.
Although the correspondence between functional-magnetic resonance imaging (fMRI) representations of the sensorimotor cortex and intraoperative electrophysiology (including somatosensory evoked potential, SSEP, recordings and direct cortical stimulation) has been reported, a similar correspondence between fMRI and intraoperative localization of the language-sensitive cortex is not as well established. The aim of the present study was to evaluate the concordance between fMRI and intraoperative electrophysiology with respect to the localization of the language-sensitive and sensorimotor cortices. We present the results of 21 patients who underwent language and sensorimotor mapping by fMRI and intraoperative electrophysiology including SSEP recordings (n = 21), direct cortical stimulation of motor cortex (n = 15) and direct cortical stimulation of Broca's and Wernicke's area (n = 5). When responses were obtained with both methods, localization of function concurred in all cases. These observations suggest that fMRI represents a reliable preoperative tool for the identification of language-sensitive areas.
The effect of head-upright tilting on the rate of cerebral autoregulation was studied in 12 healthy volunteers (nine men and three women; age range 20-36 years). The dynamics of cerebral autoregulation was determined from the rate of change in cerebral resistance (RoR) during a drop in arterial blood pressure induced by rapid deflation of a 3-min ischaemic thigh cuff and from the ratio of changes in cerebral blood flow and arterial blood pressure (CAI) during the recovery period after the drop in arterial blood pressure. The test was performed supine and with 40 degrees head-up tilt (40 degrees HUT). Middle cerebral artery mean blood flow velocity was measured by transcranial Doppler simultaneously with peripheral arterial blood pressure using Finapres. The thigh cuff deflation induced a larger drop in arterial pressure during 40 degrees HUT [median -28% (25 percentile -36, 75 percentile -19)] than in the supine position [-16% (-23, -15)] (P < 0.01) and in cerebral resistance [supine: -12% (-15, -6); 40 degrees HUT: -15% (-20, -12); P < 0.05]. There was no significant change in RoR [15% s-1 (12, 15)] and CAI [1.9 (1.5, 3.1)] measured supine and during 40 degrees HUT [RoR: 13% s-1 (12, 15); CAI: 1.3 (0.99, 1.9)]. During the drop in arterial pressure, the relationship between arterial blood pressure and systolic peak-to-peak interval exhibited an hysteresis loop, indicating a cardiopulmonary and/or baroreflex activation that was not observed with cerebral resistance. The rate of autoregulation is an intrinsic property of the cerebral vascular bed and is not affected by the vasodilator state in the range of arterial blood pressure changes induced by the tight cuff method.
Macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES production were measured by ELISA in whole blood that had been stimulated for 4.5 h with phytohemagglutinin. The blood was from 90 healthy human immunodeficiency virus (HIV)-negative controls and from 245 HIV-infected subjects who were followed for < or = 4.5 years. HIV-infected persons without AIDS had increased levels of MIP-1alpha, MIP-1beta, and RANTES (P < .01) compared with levels in controls. Subjects with AIDS, compared with controls, had decreased production levels of MIP-1beta (P < .0001) and similar levels of MIP-1alpha and RANTES. A high level of MIP-1beta production was associated with a decreased risk of progressing to AIDS or death, as determined by univariate analysis (P < .01) and adjusted for CD4 cell count and age (P = .07, P = .06, respectively). The findings suggest that the production level of beta-chemokine changes during HIV infection and that a high level of beta-chemokine production in peripheral blood lymphocytes may be associated with less rapid disease progression in HIV infection.
The effect of cardioinhibition and/or vasodepression on cerebral hemodynamics assessed by transcranial Doppler has been investigated during carotid massage in 11 patients (62-87 years, mean age 72) with carotid sinus syndrome. The patients were tested in the OOO mode (n = 11) with six tested in the DDD mode. Carotid massage in the OOO mode decreased mean arterial pressure by 44% (P < 0.01) and mean cerebral blood flow velocity by 50% (P < 0.01). Although not significant, cerebrovascular resistance increased transiently by 17% during massage, then decreased by 31% upon recovery. Carotid massage in the DDD mode decreased arterial pressure by 30% (P < 0.01), cerebral blood velocity by 23% (P < 0.01), and resistance by 15% (P < 0.05). The decreased cerebral perfusion induced by cardioinhibition and/or vasodepression results from the delayed onset of cerebral autoregulation. Pacing in the DDD mode temporarily assists the critical period preceding the onset of cerebral autoregulation that plays a key role in preventing the deleterious effects of vasodepression.
A total of 347 HIV-seropositive individuals attending the Department of Infectious Diseases at Rigshospitalet in Copenhagen and 110 age- and sex-matched healthy controls not at risk for HIV infection were included in this study. Interferon gamma (IFN-gamma) production was measured in whole blood of 223 HIV-seropositive individuals (68 had developed AIDS at enrollment) and 99 healthy sex- and age-matched controls 4.5 hr after challenge with phytohemagglutinin. HIV-infected individuals for whom IFN-gamma production was measured were followed with a median follow-up time of 2.89 years (range, 0.02-4.54 years) from the date of enrollment. Survival analysis was performed considering three different end points: (1) a CD4 count below 100 cells/mm3, (2) an AIDS diagnosis defined according to the 1993 Centers for Disease Control definition, and (3) death. The production of IFN-gamma was highly increased in the blood of HIV-infected individuals without AIDS, but decreased in the blood of AIDS patients (both compared to controls). In the HIV-infected individuals, the total production of IFN-gamma was positively correlated with the number of CD8+ T lymphocytes and with the number of CD16+/CD56+ natural killer cells and negatively correlated with serum levels of beta2-microglobulin. Low levels of IFN-gamma production were associated with an increased risk of experiencing a CD4 count below 100 cells/m3 and death, analyzed in both univariate analysis and in multivariate analysis adjusting for CD4 counts and age. Thus, changes in production of IFN-gamma seem to be truly related to the risk for disease progression in HIV infection.
A prospective study of 73 arthroscopic anterior cruciate ligament reconstructions using either a patellar tendon autograft or an allograft was made to assess any difference in clinical outcome. Allocation was by availability of an allograft. There were 48 autografts and 25 allografts. Evaluation was by clinical examination and physical tests. At follow-up 2 years after operation, there were no statistically significant differences between the two groups in mobility or in physical tests, but KT-1000 evaluation showed a slightly greater anterior translation in the autografts at 6 months and one year, although at 2 years the allografts developed greater anterior laxity. Cybex testing showed greater quadriceps strength at 6 months and one year in the allografts, but at 2 years the strength was greater in the autografts. Re-rupture occurred in 3 allografts. ACL reconstruction with a patellar tendon allograft does not produce a significant functional deficit. Full quadriceps recovery takes 2 years. Allografts are not recommended as stability deteriorates with time.
Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were measured by ELISA in 4.5-h, lipopolysaccharide-stimulated whole blood cultures of 347 human immunodeficiency virus type 1-infected patients and 107 healthy seronegative controls. The production of TNF-alpha was decreased in both AIDS and non-AIDS patients, whereas the production of IL-1beta was decreased in AIDS patients only. The production of TNF-alpha and IL-1beta was positively affected by the concentrations of CD14+ monocytes and CD8+ lymphocytes; however, in patients, the concentration of CD4+ lymphocytes and the presence of AIDS had a negative effect on cytokine production as determined by multiple linear regression analysis. It is concluded that low whole blood cytokine production is mainly caused by low numbers of cells, but a functional defect may also exist.
OBJECTIVE: To examine changes in the distribution of CD4+CD45RA+ (naive) and CD4+CD45RO+ (memory) lymphocytes in various stages of HIV infection and the effect of these changes on disease progression. DESIGN AND METHODS: Expression of CD45RA+ and CD45RO+ on CD4+ lymphocytes was analysed by flow cytometry in a prospectively followed cohort of 300 HIV-infected individuals (median follow-up time, 2.90 years; range, 0.02-4.54 years) and in a group of 102 age- and sex-matched uninfected controls. Survival analysis was performed considering AIDS development and death as endpoints. RESULTS: The median CD4+CD45RA+/CD45RO+ ratio was 1.3 (25-75% quartiles, 0.9-2.4) in controls; it was increased to 1.8 (1.1-2.5) in 40 HIV-infected individuals with CD4+ cell counts > 500 x 10(6)/l (P < 0.05); it was similar at 1.4 (0.8-2.0) in 106 HIV-infected individuals with CD4+ cell counts of 200-500 x 10(6)/l; and it was decreased to 0.9 (0.5-1.4) in 154 HIV-infected individuals with CD4+ cell counts < 200 x 10(6)/l (P < 10[-6]). When fitted in a Cox model adjusting for the total number of CD4+ cells and age a lower concentration of CD4+CD45RA+ cells was associated with an increased risk of dying. The concentration of CD4+CD45RO+ cells was not significantly associated with AIDS or death in age- and CD4+ cell count-adjusted Cox models. CONCLUSIONS: This study confirms a selective loss of memory CD4+ cells early in HIV infection followed by increased loss of naive CD4+ cells in later stages of the infection. The loss of naive CD4+ cells seems to be important in the pathogenesis of terminal HIV infection.
Stored data in implantable pacemakers have rarely been used as a diagnostic tool because of the complexity. Our group has developed software called AIDA, providing an automatic interpretation of data stored in memories of the Chorus (ELA medical) pacemaker. We compared the results of AIDA analysis to surface ECG Holter interpretation in 59 patients (age 75 +/- 9 years). In 33 cases, neither AIDA nor the Holter found any anomaly. Eleven patients demonstrated episodes of supraventricular tachycardia (SVT), confirmed by AIDA in ten patients; AIDA failure was due to nonsustained episodes of SVT not inducing mode switch. Loss of atrial sensing, pacemaker-mediated tachycardia, and ventricular extrasystoles were detected by AIDA in ten patients. Traditional Holter missed three cases. This initial study confirms that stored pacemaker data, automatically interpreted can provide reliable information over a 24-hour period.
Thirty-four total knee arthroplasties were performed for severe rheumatoid arthritis in 25 patients younger than 45 years. All patients were available for follow-up evaluation at an average of 7.2 years. According to the Knee Society scoring system, the knee score improved from an average of 21 points preoperatively to 85 points at follow-up (p < 0.001). The average functional score improved from 23 points to 87 points (p < 0.001). Average range of motion improved from 71 degrees to 93 degrees (p < 0.001). Nonprogressive radiolucencies less than 1-mm thick were observed in 6 knees. One knee was revised for severe polyethylene wear; another case was revised for chronic patellar dislocation. Actuarial survivorship analysis estimates a 97% survivorship after 5 years and 90% after after 10 years. In young rheumatoid patients, total knee arthroplasty can therefore be considered as a reliable procedure, with satisfactory results during at least the first 5 to 10 postoperative years.
Results of radiofrequency ablation of the atrioventricular junction on functional capacity and left ventricular systolic function were assessed in 8 patients (aged 68 +/- 12 years) with refractory atrial fibrillation and severe left ventricular dysfunction, the mean ejection fraction being 31 +/- 11% (range: 20-48%). A clinical, echocardiographic and angioscintigraphic follow-up was performed 24 hours (basal), 3 and 6 months after the procedure. During follow-up, all patients reported the disappearance of palpitations and tiredness, a significant and early regression of effort dyspnoea from average NYHA Class 3.4 +/- 0.7 to 2.2 +/- 0.4 (M3), (p < 0.01), a decrease in end diastolic echocardiographic dimensions (from 57 +/- 10 to 52 +/- 9 mm (M3); p < 0.05) resulting in an increase in fractional shortening from 26 +/- 7% to 34 +/- 6%; p < 0.05. The isotopic EF increased from 31 +/- 11% to 42 +/- 12% (M3) (p < 0.01), and attained 48 +/- 12% (M6). This study shows that controlling the frequency and regularity of cardiac rhythm by ablation of the atrioventricular junction in patients with refractory AF and left ventricular dysfunction results in functional and haemodynamic improvement, especially when there is no apparent underlying cardiac disease. This suggests that this method should be proposed in all patients with refractory atrial fibrillation and left ventricular dysfunction.
A high degree atrioventricular block (AVB) is an exceptional finding during an acute episode of rheumatic fever (RF). The authors report a case of complete syncopal AVB requiring a temporary pacemaker, representing the first episode of RF.
Based on the results of our study, > 95% of patients with a positive passive tilt test are also positive during 3 micrograms/min, and especially 5 micrograms/min, isoproterenol tilt test. A proposed time-saving protocol would be to initiate the test with an isoproterenol infusion and to perform a 45-minute passive tilt only in those patients with a positive 5 micrograms/min (an infusion rate reported to have an excessive low specificity) isoproterenol tilt test, and to consider only those with symptoms associated with objective changes during this latter test as "finally positive." An alternative option would be to perform a 45-minute passive tilt only in those patients with a negative 3 micrograms/min isoproterenol tilt test.
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Various authors have indicated that imbalance of the vastus medialis/vastus lateralis muscles might lead to patellofemoral pain syndrome. However, few reports have been published to substantiate such a hypothesis. The purpose of this study was to attempt to set a scale for the normal reflex response times of the vastus medialis oblique and vastus lateralis muscles after a patellar tendon tap and to determine if patellofemoral pain syndrome patients have an alteration in this firing sequence. A control group of 80 healthy adults was compared with a group of 19 patellofemoral pain syndrome patients. Results indicated that the reflex response time of the vastus medialis oblique was significantly shorter than the reflex response time of the vastus lateralis in the normal subjects (p < or = .01). When comparing these data in the patellofemoral pain syndrome group, a significant earlier firing was obtained from the vastus lateralis in comparison with the vastus medialis oblique (p < or = .01). These findings suggest that a reversal has occurred in the firing pattern of the vastus medialis oblique and vastus lateralis muscles in patellofemoral pain syndrome patients. The results indicate an alteration in the neuromuscular answer of the vastus medialis oblique and vastus lateralis muscles during a patellar tendon tap.