Pierre Graux

Interference Between Pacemaker and Video Capsule Endoscopy

The wireless capsule video endoscopy is useful in patients with occult blood loss, but is contraindicated in patients with cardiac pacemaker (PM). No case of interference has been published. We report the case of a patient with a PM implanted in the abdominal wall. After capsule ingestion, cardiac monitoring showed no modification of the PM compartment (VOO, unipolar mode) but the capsule recording reveal more than 3 hours of loss of image. The wireless capsule endoscopy is safe in patients with PMs in VOO mode. Nevertheless important interference was noted in the recording when the capsule was near the PM.

Prospective evaluation of high-dose or low-dose isoproterenol upright tilt protocol for unexplained syncope in young adults

The sensitivity of the passive head-up tilt test (HUT) in the evaluation of unexplained short-lasting syncope in young adults remains insufficient. The infusion of isoproterenol was proposed to improve the benefit. To evaluate the sensitivity-specificity relationship during isoproterenol dosing, we studied 76 young adults (aged 20.9 +/- 1.7 years) (group S) with recurrent (mean 3.8 +/- 1.6) losses of consciousness that remained unexplained after clinical and noninvasive assessment and 35 young healthy volunteers (aged 22.6 +/- 2.7 years) (group V). Subjects underwent either passive HUT (45 min, 60 degrees without drug dosing for 48 subjects in group S (S1) and 17 in group V (V1), or HUT with isoproterenol infusion at progressive doses (2 then 5 micrograms/min) after 30 minutes of passive tilting for 28 patients in group S (S2) and 18 in group V (V2). During passive HUT, the test was positive (asystole, bradycardia, or fall in systolic blood pressure) in 2 of 17 (11.8%) patients in group V1 and in 7 of 48 (14.6%) in group S1 before 30 minutes, and in 3 of 17 (17.6%) in group V1 compared with 10 of 48 (20.8%) in group S1 at the end of the 45-minute infusion, with no difference in delay before the appearance of a positive result. During HUT with isoproterenol dosing, the test was positive in 2 of 18 (11.1%) patients in group V2 and in 18 of 28 (64.2%) in group S2 before 45 minutes (2 micrograms/min; p < 0.01) in 7 of 18 (38.8%) in group V2 compared with 24 of 28 (85.7%) in group S2 before 60 min (5 micrograms/min; p < 0.01). In both cases the mean delay in evoking a positive response was significantly shorter. No asystolic response was observed in the volunteers regardless of the protocol used. The most characteristic response to isoproterenol injection was the appearance of a junctional escape rate with a fall in systolic blood pressure (61.5% of subjects in group S2). The infusion of isoproterenol considerably improves the sensitivity of the HUT with satisfactory specificity if low doses are used (< 3 micrograms/min). These results support the use of HUT with isoproterenol in the evaluation of unexplained syncope in young adults.

Prospective comparison of speckle tracking longitudinal bidimensional strain between two vendors

BACKGROUND Speckle tracking is a relatively new, largely angle-independent technique used for the evaluation of myocardial longitudinal strain (LS). However, significant differences have been reported between LS values obtained by speckle tracking with the first generation of software products. AIMS To compare LS values obtained with the most recently released equipment from two manufacturers. METHODS Systematic scanning with head-to-head acquisition with no modification of the patients position was performed in 64 patients with equipment from two different manufacturers, with subsequent off-line post-processing for speckle tracking LS assessment (Philips QLAB 9.0 and General Electric [GE] EchoPAC BT12). The interobserver variability of each software product was tested on a randomly selected set of 20 echocardiograms from the study population. RESULTS GE and Philips interobserver coefficients of variation (CVs) for global LS (GLS) were 6.63% and 5.87%, respectively, indicating good reproducibility. Reproducibility was very variable for regional and segmental LS values, with CVs ranging from 7.58% to 49.21% with both software products. The concordance correlation coefficient (CCC) between GLS values was high at 0.95, indicating substantial agreement between the two methods. While good agreement was observed between midwall and apical regional strains with the two software products, basal regional strains were poorly correlated. The agreement between the two software products at a segmental level was very variable; the highest correlation was obtained for the apical cap (CCC 0.90) and the poorest for basal segments (CCC range 0.31-0.56). CONCLUSIONS A high level of agreement and reproducibility for global but not for basal regional or segmental LS was found with two vendor-dependent software products. This finding may help to reinforce clinical acceptance of GLS in everyday clinical practice.

A randomized, single-blind crossover comparison of the effects of chronic DDD and dual sensor VVIR pacing mode on quality-of-life and cardiopulmonary performance in complete heart block

The aim of this study was to compare DDD and dual sensor VVIR (activity and QT) pacing modes in complete AV block (CAVB). Eighteen patients (14 men and 4 women, aged 70 ± 6.5 years) implanted with a dual chamber, dual sensor pacemaker for CAVB with normal sinus node chronotropic function were studied. A quality‐of‐life and cardiovascular symptom questionnaire, and a treadmill exercise test were completed after a period of VVIR and a period of DDD pacing, each lasting 1 month. Overall quality‐of‐life and cardiovascular symptoms did not significantly differ, though three patients felt discomfort during VVIR mode. There was no significant statistical difference in Cardiopulmonary parameters. DDD and VVIR modes yielded the following respective data: maximum heart rate = 105.7 ± 21.8 beats/minute versus 107.6 ± 21.6 beats/minute (NS); maximum workload = 60 ± 33.4 W versus 59.3 ± 37.8 W (NS); treadmill duration = 10.1 ± 3.8 minute versus 10.1 ± 3.6 minute (NS); oxygen consumption at anaerobic threshold = 14.6 ± 4.1 ml/kg per minute versus 14.9 ± 4.6 mL/kg per minute (NS); maximum minute ventilation = 49.6 ± 9 L/min versus 46 ± 12 L/min (NS); and respiratory quotient = 1.08 ± 0.15 versus 1.08 ± 0.13 (NS). We conclude that, during a 1‐month follow‐up period, no difference was found between DDD and dual sensor VVIR (QT and activity) pacing modes in CAVB patients with regard to quality‐of‐life and Cardiopulmonary performance, though a trend toward an increased sense of well being was noted with the DDD mode.

Mechanisms of onset of atrial fibrillation: a multicenter, prospective, pacemaker-based study.

The aim of this study was to analyze the onset mechanisms of atrial tachyarrhythmias using a dedicated diagnostic system in 83 recipients of DDDR pacemakers implanted for standard clinical indications. The pulse generator was programmed in DDD mode, at 60 beats/min, and the diagnostic instrument was programmed to document atrial tachyarrhythmic episodes at rates >200 beats/min. Onset mechanism was defined as the combination of ambient rhythm and trigger. Various underlying rates and rhythms patterns, including tachycardia, increasing frequency of premature atrial complex (PAC), underlying heart rate increase, restart, and no specific underlying rhythm, and various triggers, including single, multiple, or short runs of PACs, sudden rate decrease, and sudden onset of atrial tachyarrhythmia were included in the combined classification. Atrial tachyarrhythmic episodes were documented on one follow‐up interrogation in 48 of the 83 patients. The pacing indications consisted of high degree atrioventricular block in 19 patients, bradycardia‐tachycardia syndrome in 22, and isolated sinus node dysfunction in 6 patients. The onset mechanisms of 318 episodes were recorded and analyzed. A variety of triggers were observed in 33 of the 48 patients, and 39 patients had various ambient rhythms. Among 20 documented onset mechanisms, the most common were increasing frequency of PAC + short runs (17%), no specific ambient rhythm + sudden onset (24%), and increasing frequency of PAC + sudden onset (12%). There were wide intra‐ and interpatient variations in onset mechanisms, suggesting that state‐of‐the‐art pacemakers should represent versatile diagnostic tools and offer flexible pacing methods to refine the management of atrial tachyarrhythmias. (PACE 2003; 26:1336–1341)

Is mechanical dyssynchrony a therapeutic target in heart failure with preserved ejection fraction

BACKGROUND Previous studies have found a high frequency of mechanical dyssynchrony in patients with heart failure (HF) with preserved ejection fraction (HFpEF), hence suggesting that cardiac resynchronization therapy (CRT) may be considered in HFpEF. The present study was designed to compare the amount of mechanical dyssynchrony between HFpEF patients and (1) HF with reduced EF (HFrEF) patients with an indication for CRT (HFrEF-CRT(+)) group, (2) HFrEF patients with QRS duration < 120 ms (HFrEF-QRS < 120 ms) group, and (3) hypertensive controls (HTN). METHODS Electrical (ECG) and mechanical dyssynchrony (atrio-ventricular dyssynchrony, interventricular dyssynchrony, intraventricular dyssynchrony) were assessed using conventional, tissue Doppler, and Speckle Tracking strain echocardiography in 40 HFpEF patients, 40 age- and sex-matched HTN controls, 40 HFrEF-QRS < 120 ms patients, and 40 HFrEF-CRT(+) patients. RESULTS The frequency of left bundle branch block was low in HFpEF patients (5%) and similar to HTN controls (5%, P = 0.85). Indices of dyssynchrony were similar between HFpEF and HTN patients or HFrEF-QRS < 120 ms patients. In contrast, most indices of dyssynchrony differed between HFpEF and HFrEF-CRT(+) patients. The principal components analysis on the entire cohort of 160 patients yielded 2 homogeneous groups of patients in terms of dyssynchrony, the first comprising HFrEF-CRT(+) patients and the second comprising HTN, HFrEF-QRS < 120 ms and HFpEF patients. CONCLUSIONS Mechanical dyssynchrony in HFpEF does not differ from that of patients with HTN or patients with HFrEF and a narrow QRS. This data raises concerns regarding the role of dyssynchrony in the pathophysiology of HFpEF and thereby the potential usage of CRT in HFpEF.

Clinical and echocardiographic correlates of plasma B-type natriuretic peptide levels in patients with aortic valve stenosis and normal left ventricular ejection fraction.

Background: Several studies suggest that BNP testing may help define the timing of aortic valve surgery in patients with aortic valve stenosis (AVS) prior onset of overt LV systolic dysfunction. The aim of this study was to identify clinical and echocardiographic correlates of plasma BNP levels in a large cohort of patients with AVS and preserved LV ejection fraction. Method and results: One hundred thirty‐five consecutive patients were prospectively included in the present study (Mean age 73 ± 13 years old, 66 (49%) male). Eighty‐nine patients (66%) had severe AVS (aortic valve area <0.6 cm2/m2 BSA). Plasma BNP levels, clinical and comprehensive Doppler echocardiography evaluation was performed in all patients. Independent clinical correlates of plasma BNP levels (R2= 0.19) were older age (P < 0.0001) and presence of AVS symptoms (P = 0.004). Independent echocardiographic correlates of plasma BNP levels (R2= 0.38) were E/Ea ratio (P = 0.01), LV mass index (P = 0.018), left atrial surface (P < 0.0001) and systolic pulmonary artery pressure (sPAP; P = 0.004). Overall, independent correlates of plasma BNP levels (R2= 0.47) were older age (P = 0.001), known coronary artery disease (P = 0.047), increased LV mass index (P = 0.001), left atrial enlargement (P = 0.002), and increased sPAP (P = 0.003). Conclusions: In patients with AVS and normal LV ejection fraction, plasma BNP predominantly reflects the clinical and echocardiographic consequences of afterload burden imposed on the left ventricle rather than the severity of valve stenosis, per se. (Echocardiography 2011;28:695‐702)

Prognostic value of left ventricular reverse remodeling and performance improvement after cardiac resynchronization therapy: A prospective study.

BACKGROUND The present study was designed to evaluate the respective value of left ventricular (LV) reverse remodeling (changes in LV end-systolic volume relative to baseline (ΔLVESV)) or LV performance improvement (ΔLV ejection fraction (ΔLVEF) or ΔGlobal longitudinal strain (GLS)) to predict long-term outcome in a prospective cohort of consecutive patients receiving routine cardiac resynchronization therapy (CRT). METHODS One hundred and seventy heart failure patients (NYHA classes II-IV, LVEF ≤ 35%, QRS width ≥ 120 ms) underwent echocardiography before and 9 months after CRT. The relationships between ΔLVESV, ΔLVEF, ΔGLS and outcome (all-cause mortality and/or CHF hospitalization, overall mortality, cardiovascular mortality, CHF hospitalization) were investigated. RESULTS During a median follow-up of 32 months, 20 patients died and 27 were hospitalized for heart failure. ΔLVESV, ΔLVEF or ΔGLS were significantly associated with all-cause mortality or CHF hospitalization (adjusted hazards ratio (HR) per standard deviation 0.58 (0.43-0.77), 0.39 (0.27-0.57) or 0.55 (0.37-0.83) respectively, all p < 0.01) and all other endpoints (all p < 0.01). Patients with ΔLVESV≥15%, ΔLVEF ≥ 10% and ΔGLS ≥ 1% had a reduced risk of mortality or CHF hospitalization (adjusted HR=0.25 (0.12-0.51), p < 0.001, adjusted HR = 0.26 (0.13-0.54), p < 0.001 and adjusted HR 0.38 (0.19-0.75), p = 0.006 respectively). Overall performance of multivariate models was better using ΔLVESV or ΔLVEF compared with ΔGLS. Interobserver agreement was excellent for ΔLVESV (Intraclass correlation coefficient - ICC-0.91) and ΔGLS (ICC 0.90) but modest for ΔLVEF (ICC 0.76) in a sample of 20 patients from the study population. CONCLUSIONS LV reverse remodeling assessed by ΔLVESV is a strong and reproducible predictor of outcome following CRT. Compared with ΔLVESV, ΔLVEF and ΔGLS have important shortcomings: poorer reproducibility or lower predictive value.

WAVELENGTH AND ATRIAL VULNERABILITY : AN ENDOCAVITARY APPROACH IN HUMANS

If atrial vulnerability parameters are well defined, wavelength (WL) measurement (conduction velocity x refractory period), has never been assessed through an endocavitary electrophysiological exam.

Indications for multisite pacing in patients with heart failure

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