Yves Guyomar

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.

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)

Frequency of Atrial Tachyarrhythmias in Patients Treated by Cardiac Resynchronization (from the Prospective, Multicenter Mona Lisa Study)

The continuous measurement of sustained atrial tachyarrhythmia (AT) is now possible with some permanently implanted devices. Data on this subject remain controversial. The aim of this study was to evaluate the incidence of sustained AT in patients treated with cardiac resynchronization therapy using pacemakers without backup defibrillators (CRT-P), within the first year after implantation, using strict definition criteria for sustained AT and a systematic review of all high-quality electrographically recorded episodes. The Mona Lisa study was a prospective, multicenter, cohort study carried out from February 2004 to February 2006, with a 12-month follow-up period. Sustained AT was defined as an episode lasting > or =5 minutes; episodes were confirmed by a systematic review of electrograms in the whole study population. Of the 198 patients who underwent CRT-P device implantation and were enrolled in the study, 173 were in stable sinus rhythm at baseline and were included in the analysis (mean age 70 +/- 9 years, 66% men, 91% in New York Heart Association class III, mean QRS duration 164 +/- 26 ms, mean left ventricular ejection fraction 25 +/- 7%). During a mean follow-up period of 9.9 +/- 3.6 months, 34 patients experienced > or =1 episode of sustained AT, for an incidence rate of 27.5% (95% confidence interval 18.2 to 36.7). Only a history of AT was independently associated with the occurrence of sustained AT within the 12 months after CRT-P device implantation (hazard ratio 2.3, 95% confidence interval 1.2 to 4.4, p = 0.02). In conclusion, this first prospective electrogram-based evaluation of AT incidence demonstrated that 27% of patients developed > or =1 episode of sustained AT lasting > or =5 minutes in the 12 months after CRT-P device implantation.

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.

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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Reliability of single-lead VDD atrial sensing and pacing during exercise.

If atrial sensing ability of a single‐lead VDD pacemaker is well accepted at rest, the detection quality by atrial floating electrodes remains less recognized during exercise. The aim of this study was to verify, during tread‐mill test and a continous telemetry, the atrial tracking performance using four different leads technologies. From November 1994 to July 1997, 21 patients (71.3 ± 6.3 years old. 7 female, cardiopathy: 57%) were paced for isolated high degree (permanent: 13, paroxystic: 8) AV block. The implanted devices were the Vitatron Saphir/Brillant lead (13 patients), Intermedics Unity/425/04–13 lead (5 patients), Pacesetter Addvent (2 patients), and Biotronik Eikos (1 patient). The acute atrial signal amplitude was 1.66 ± 0.75 mV. The treadmill test used the chronotropic assessment exercise protocol after pacemaker reprogramming to detect atrial undersensing (AV delay ≤ 120 ms, no hysteresis, no flywheel, upper rate increase). The mean delay was 31.1 weeks (range 1–100). The testing duration was 6.1 ± 2.3 minutes, the number of steps was 3.3 ± 1.3 per patient, and the peak exercise rate was 135 ± 19 beats/min. At rest, complete atrial tracking was complete in 90% of the patients, and during testing in only 23.8% of the patients, while AV synchronization > 95% was present in 57.1%, > 90% in 71.4%, and > 85% in 90.4% of patients (Vitatron 13/13, Intermedics 3/5, Biotronik 1/1, and Pacesetter 1/2). During the recovery period synchronization was always > 95%. The mean P wave amplitude at rest was 1.1 ± 0.5 mV; during the first step, 1.04 ± 0.61 mV; second step, 0.94 ± 0.53 mV; third step, 0.82 ± 0.58 mV; fourth step, 0.67 ± 0.39 mV; and during recovery, 1.13 ± 0.67 mV. The mean P wave decrease signal at peak of exercise is 0.21 mV (from ‐1.31 to +0.5). In fact, P wave variations have several patterns: a decrease was measured in 7 patients, an increase in 2 patients, and no significant change in 7 patients. Single‐lead VDD P wave identification during exercise was almost accurate. However, often there was progressive lowering of atrial sensing with transient loss of AV synchrony.

Two-dimensional speckle-tracking echocardiography for atrioventricular accessory pathways persistent ventricular pre-excitation despite successful radiofrequency ablation

AIMS The present study was undertaken to investigate the concordance between longitudinal two-dimensional (2D)-speckle-tracking data and endocardial mapping for localizing atrioventricular accessory pathways (AP), and whether longitudinal 2D-speckle-tracking imaging accurately identifies the contractile abnormalities associated with AP and the effect of radiofrequency ablation. METHODS AND RESULTS Echocardiograms were repeated twice in 40 patients with Wolff-Parkinson-White (WPW) syndrome (before and early after ablation) and in 40 healthy controls to obtain longitudinal 2D strain and strain rate data. The site of ablation was considered as the gold standard for the AP localization. While control patients had a homogeneous strain pattern, all but two patients with WPW had an abnormal deformation pattern with three peaks in one or two basal contiguous segments: an early peak concomitantly with the delta wave followed by a systolic and a post-sytolic one. The rapid increase in LV longitudinal deformation within the basal pre-excited zone resulted in a pre-systolic peak strain rate at the beginning of the delta wave by SR imaging that was not found in controls. The early basal contraction spread towards the mid-ventricle before merging with the normal activated segments in 15 patients (39%). Contractile abnormalities were no more than one adjacent segment different compared with the AP ablation site in all these 38 patients. Regional strain was impaired in the pre-excited areas especially in AP localized in the interventricular septum. The abnormal deformation pattern persisted in 16 (42%) patients despite successful radiofrequency ablation. However, the difference in the regional strain between WPW patients and controls did not remain after ablation. CONCLUSION Longitudinal 2D-speckle-tracking data accurately match with endocardial mapping findings for localizing AP. Longitudinal 2D-speckle-tracking imaging accurately identifies AP-associated contractile abnormalities. Longitudinal 2D-speckle-tracking identifies persistence of local ventricular pre-excitation immediately after successful ablation.