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Biomedical subjects

Jacques Victor

Publications and source records attributed to Jacques Victor.

11 recordsLinked to original sources
PubMed2006

Use of a new cardiac pacing mode designed to eliminate unnecessary ventricular pacing.

AIMS: To examine the performance of AAIsafeR2, a new pacing mode to minimize the cumulative proportion of ventricular pacing in patients who do not need regular ventricular support. METHODS AND RESULTS: The safety of AAIsafeR2 was examined in 123 recipients (73 +/- 12 years old, 51% men) of dual chamber pacemakers implanted for sinus node dysfunction, paroxysmal AV block or the bradycardia-tachycardia syndrome. Data were collected from pacemaker diagnostics, and the first 43 patients underwent 24-h Holter recordings before being discharged from the hospital with AAIsafeR2 activated. No adverse event related to AAIsafeR2 was observed. All ventricular pauses detected on Holter tapes triggered immediate back-up ventricular pacing. Appropriate switches to DDD occurred in 97 of 123 patients. In 69 of 123 devices (56%) switches to DDD were non-sustained, and the average % ventricular pacing in this group was 0.2+/-0.5%. CONCLUSION: AAIsafeR2 mode seems to be safe and reliable in patients with infrequent slowing or pauses in ventricular activity, while maintaining ventricular pacing below 1%.

Aged↗
PubMed2006

Progressive cardiac conduction defect is the prevailing phenotype in carriers of a Brugada syndrome SCN5A mutation.

INTRODUCTION: Loss-of-function mutations in the SCN5A gene encoding the cardiac sodium channel are responsible for Brugada syndrome (BS) and also for progressive cardiac conduction disease (inherited Lenègre disease). In an attempt to clarify the frontier between these two entities, we have characterized cardiac conduction defect and its evolution with aging in a cohort of 78 patients carrying a SCN5A mutation linked to Brugada syndrome. METHODS AND RESULTS: Families were included in the study if a SCN5A mutation was identified in a BS proband and if at least two family members were mutation carriers. Sixteen families met the study criteria, representing 78 carriers. Resting ECG showed a spontaneous BS ECG pattern in 28 of 78 (36%) gene carriers. Intraventricular conduction anomalies were identified in 59 of 78 gene carriers including complete (17) or incomplete (24) right bundle branch block, right bundle branch block plus hemiblock (6), left bundle branch block (1), hemiblock (1), and parietal block (10). PR and QRS duration were longer in the gene carrier cohort in comparison with their relatives carrying no mutation. Finally, in the gene carrier cohort conduction defect progressively aggravated with aging leading in five occasions to pacemaker implantations. CONCLUSION: The present study shows that the most common phenotype of gene carriers of a BS-type SCN5A mutation is progressive cardiac conduction defects similar to the Lenègre disease phenotype. In consequence, we propose that carriers of a SCN5A mutation need a clinical and ECG follow-up because of the risk associated with severe conduction defects.

Adolescent↗
PubMed2005

Do we need a reflex tachycardia to stand up?

BACKGROUND: Sophisticated atrio-ventricular pacing models are designed to integrate the pacemaker into cardiovascular autonomic control to react appropriately to the cardiovascular demands. Such an approach might be beneficial for patients with vasovagal responses to counterbalance the upright fall in arterial blood pressure by a pacing rate increase. We hypothesized that this approach would improve the cardiovascular response to standing in comparison with a regular pacing mode. METHODS: Two 5-minute tilt tests were performed in a random order in 5 patients with a pacemaker (CLS-INOS(2)) for sinus node disease and atrio-ventricular block. One tilt test was performed in fixed pacing rate (DDD), the other one was performed in close loop stimulation (CLS), which allowed an upright rate-rise pacing. Heart rate, systolic blood pressure, and cardiac output (modelflow) were recorded on a beat-by-beat basis. RESULTS: Changes of systolic blood pressure and cardiac output in response to upright posture were not significantly different between DDD and CLS modes (2.7 +/- 13.2 vs 10.1 +/- 12.9 mmHg and -0.8 +/- 0.3 vs -1.1 +/- 0.4 L/min, respectively). But upright posture led to a tachycardia of more than 30 bpm in 3 patients in CLS mode and to a fall in systolic blood pressure greater than 20 mmHg in 3 patients in CLS mode and only in one patient in DDD mode. CONCLUSION: Systolic blood pressure and cardiac output are not improved by the upright tachycardia and upright blood pressure response is actually worsened when an upright rate-rise pacing is used. Thus, it appears that tachycardia alone cannot compensate for an upright fall in blood pressure.

Aged↗
PubMed2005

Late hemodynamic changes during a negative passive head-up tilt predict the symptomatic outcome to a nitroglycerin sensitized tilt.

BACKGROUND: Sublingual nitroglycerin is advocated to sensitize the passive 70 degrees head-upright tilt test (HUTT) of patients with unexplained syncope. We hypothesized that a detailed analysis of hemodynamic responses recorded during a negative HUTT could predict the outcome to a subsequent nitroglycerin sensitized HUTT (NTG-HUTT). METHODS: Thirty-two patients (46 +/- 3 years, 17 males) with recurrent unexplained syncope but a negative HUTT were included. Heart rate, arterial blood pressure, and central hemodynamics assessed by transthoracic impedance (preejection and rapid left ventricular ejection time, slow ejection time, peak amplitude of first derivative, and cardiac index) were recorded during supine rest and 45 minutes HUTT. Changes from supine rest of the variables were retrospectively compared between patients with a negative (n = 15, NTG-HUTT(-)) and positive (n = 17, NTG-HUTT(+)) outcome to 10 minutes subsequent NTG-HUTT. RESULT: Significant differences between groups were observed during the 15th-20th minutes (Italian protocol) and during the last 5 minutes of passive HUTT (Westminster protocol). The combination of cutoff values, determined by receiver operating curves, on hemodynamic variables changes during the last 5 minutes predicted the outcome to a NTG-HUTT with a sensitivity of 76% and a specificity of 87%. The cutoff values determined during 15th-20th minutes gave an attractive sensitivity (85%) but a too weak specificity (53%) to shorten the 45 minutes passive HUTT at 20 minutes. CONCLUSION: Outcome to a NTG-HUTT can be reliably predicted by selected criteria determined from multiple hemodynamic variables recorded during a passive 70 degrees HUTT.

Analysis of Variance↗
PubMed2004

Fever as a precipitant of idiopathic ventricular fibrillation in patients with normal hearts.

INTRODUCTION: Ventricular fibrillation (VF) is the main mechanism of sudden cardiac death. The clinical precipitants of sudden cardiac death due to idiopathic VF are poorly characterized. Emerging evidence implicates triggers originating predominantly from the distal Purkinje arborization and the right ventricular outflow tract. METHODS AND RESULTS: We report three patients without structural heart disease or repolarization abnormalities in whom a febrile illness was the only concurrent disease associated with unexpected sudden cardiac death due to VF storm. An automated defibrillator was implanted in all three patients. In one patient with persistent recurrent VF episodes, mapping demonstrated the origin of these triggers was from the Purkinje arborization of the anterior wall of the right ventricle. Ablation at a site of earliest activation during ectopy, where pace mapping was concordant and Purkinje potential preceded the onset of ventriculogram, resulted in suppression of all arrhythmias. After follow-up of 22, 9, and 18 months in the three patients, no ventricular arrhythmias have been recorded. CONCLUSION: We present a series of patients in whom an apparently benign febrile illness was associated with malignant ventricular arrhythmias in the absence of cardiac disease or other factors known to precipitate sudden cardiac death. Physicians should be aware of this possible phenomenon in cases of febrile illness associated with syncope.

Aged↗
PubMed2003

Changes in the transthoracic impedance signal predict the outcome of a 70 degrees head-up tilt test.

We determined whether early changes in central haemodynamics, as determined by transthoracic impedance, induced by a 70 degrees head-up tilt (HUT) test could predict syncope. Heart rate, arterial blood pressure and central haemodynamics [pre-ejection period and rapid left ventricular ejection time ( T (1)), slow ejection time ( T (2)) and d Z /d t (max) (where Z is thoracic impedance), assessed by the transthoracic impedance technique], were recorded during supine rest and during a 45 min 70 degrees HUT test in 68 patients (40+/-2 years) with a history of unexplained recurrent syncope. We found that 38 patients (42+/-3 years) had a symptomatic outcome to 70 degrees HUT (fainters) and 30 (39+/-2 years) had a negative outcome (non-fainters). When measured between 5 and 10 min of 70 degrees HUT, T (2) had increased significantly only in the fainters, and a change in T (2) of >40 ms from baseline predicted a positive outcome with a sensitivity of 68% and a specificity of 70%. During supine rest prior to 70 degrees HUT, the fainters exhibited a shorter T (2) than non-fainters (183+/-10 compared with 233+/-14 ms; P <0.01), and a T (2) of <199 ms predicted a positive outcome to 70 degrees HUT with a sensitivity of 68% and a specificity of 63%. Incorporation of the changes that occurred from rest to 70 degrees HUT in other haemodynamic variables (heart rate >11 beats/min, systolic pressure <2 mmHg, diastolic pressure <7 mmHg and pulse pressure <-3 mmHg) increased the specificity to 97% and the positive predictive value to 93%. Thus transthoracic impedance could detect differences in central haemodynamics between fainters and non-fainters during supine rest and during the initial period of 70 degrees HUT with a consistent sensitivity and specificity when combined with peripheral haemodynamic variables.

Adolescent↗
PubMed2003

Haemodynamic response to peripheral venous congestion in patients with unexplained recurrent syncope.

In patients with recurrent unexplained syncope, exaggerated peripheral venous pooling and impaired circulatory adjustment is thought to contribute to the outcome of a head-up tilt (HUT) test. The present study investigated the role of leg volume changes during venous congestion in the haemodynamic response of patients with recurrent unexplained syncope and the ability to predict the outcome of a HUT test. Changes in calf volume (strain gauge plethysmography), heart rate and arterial blood pressure were recorded in 60 patients with history of unexplained syncope (without postural tachycardia symptom) during venous congestion provoked by pneumatic thigh cuffs while supine at rest and during the initial 10 min of a 45 min 70 degrees HUT test. Twenty-seven patients [age (mean+/-S.D.), 39+/-16 years] exhibited symptoms [HUT(+)] and 33 patients (45+/-14 years) were asymptomatic [HUT(-)]. During venous congestion, mean+/-S.E.M. calf volume increased in both groups [HUT(-), 4.5+/-0.2; HUT(+), 4.8+/-0.4 ml x 100 ml(-1), not significant), but significantly less during head-upright tilt [HUT(-), 3.3+/-0.2, P <0.01; HUT(+), 2.6+/-0.3 ml x 100 ml(-1), P <0.001] without differences between the groups. During venous congestion, arterial pressure increased significantly in asymptomatic HUT(-) patients, but not in the HUT(+) patients. Calf volume changes did not correlate with a symptomatic outcome to a 70 degrees HUT. The lack of exaggerated venous pooling during venous congestion and the inability of calf volume changes to predict a positive HUT suggest that excessive venous pooling does not contribute to the outcome of HUT. Attenuated changes in arterial pressure during venous congestion while supine suggest impaired adjustment of peripheral resistance to leg venous occlusion.

Adult↗
PubMed2003

Programming optimal atrioventricular delay in dual chamber pacing using peak endocardial acceleration: comparison with a standard echocardiographic procedure.

Optimization of programmed atrioventricular delay in dual chamber pacing is essential to the hemodynamic efficiency of the heart. Automatic AV delay optimization in an implanted pacemaker is highly desirable. Variations of peak endocardial acceleration (PEA) with AV delay at rest correlate well with echocardiography derived observations, particularly with end-diastolic filling and mitral valve closure timings. This suggests the possibility of devicing a procedure for the automatic determination of the optimal AV delay. The aim of this study was to compare a proposed algorithm for optimal AV delay determination with an accepted echocardiographic method. Fifteen patients with high degree AV block received BEST-Living pacing systems. Automatic AV delay scans were performed at rest (60-300 ms in 20-ms steps with 60 beats per step) in DDD at 90 ppm, while simultaneously recording cycle-by-cycle PEA values, which were averaged for each AV delay to obtain a PEA versus AV delay curve. Nonlinear regression analysis based on a Boltzmann sigmoid curve was performed, and the optimal AV delay (OAVD) was chosen as the sigmoid inflection point of the regression curve. The OAVD was also evaluated for each patient using the Ritter echocardiographic method. Good sigmoid fit was obtained in 13 of 15 patients. The mean OAVD obtained by the PEA sigmoid algorithm was 146.9 +/- 32.1 ms, and the corresponding result obtained by echocardiography was 156.4 +/- 34.3 ms (range 31.8-39.7 ms). Correlation analysis yielded r = 0.79, P = 0.0012. In conclusion, OAVD estimates obtained by PEA analysis during automatic AV delay scanning are consistent with those obtained by echocardiography. The proposed algorithm can be used for automatic OAVD determination in an implanted pacemaker pulse generator.

Aged↗
PubMed2002

Comparison between isoproterenol and nitroglycerin sensitized head-upright tilt in patients with unexplained syncope and negative or positive passive head-up tilt response.

It is unknown if the head-upright tilt test in patients who receive isoproterenol and nitroglycerin can identify different populations with vasovagal syncope. The aim of this study was to compare the positive or negative responses to passive tilt between isoproterenol- and nitroglycerin-sensitized upright tilt. Ninety-six patients referred for unexplained recurrent syncope underwent passive tilt (45 minutes at 70 degrees angle), which was then systematically followed, within the same session and in a random order, by a 20-minute tilt at a 70 degrees angle after administration of nitroglycerin (NTG-tilt) and 10-minute tilt at a 70 degrees angle with a continuous infusion of isoproterenol (ISO-tilt). NTG-tilt led to significantly more positive responses than passive tilt or ISO-tilt (55% vs 34% vs 42%, respectively). In the subgroup of patients with a positive response during passive tilt, the percentage of positive responses with NTG-tilt was significantly higher than with ISO-tilt (94% vs 67%). The agreement between NTG-tilt and ISO-tilt was very weak (Kappa coefficient 0.06). In the subgroup of patients with a negative response during passive tilt, the percentage of positive responses between NTG-tilt and ISO-tilt was similar (35% vs 29%). The agreement between NTG-tilt and ISO-tilt was good (Kappa coefficient 0.34). NTG-tilt led to a higher number of positive responses than ISO-tilt, especially when passive tilt outcome was positive. These 2 pharmacologic agents may identify 2 different subpopulations of patients because of their specific pharmacologic actions.

Adolescent↗
PubMed2002

Holter changes resulting from right-sided and bilateral infrastellate upper thoracic sympathectomy.

BACKGROUND: We tested the hypothesis that no right-sided dominance exists after infrastellate surgical upper-thoracic sympathectomy. We aimed to confirm whether a significant bradycardia was constant and only dependent on the right side. METHODS: We performed 24-hour Holter electrocardiographic recordings in 12 patients referred for bilateral sympathectomy. Surgery was performed at two distinct times allowing for the study of the consequences of unilateral right and bilateral sympathectomy. RESULTS: Heart rate was 77 +/- 8 beats per minute before surgery on the 24-hour recording and significantly decreased after bilateral (67.8 +/- 6.5 beats per minute; p < 0.05) but not after unilateral right sympathectomy. Consistently spectral analysis variables significantly changed after bilateral surgery but showed no right-sided dominance. Little effect of sympathectomy was found on the QT interval, which tended to decrease after bilateral sympathectomy. CONCLUSIONS: Patients should be informed of the bradycardia resulting from sympathectomy. No right-sided dominance can be found consistently with the random distribution of substellate cardiac fibers reported in anatomic studies.

Adult↗