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S Garrigue

Publications and source records attributed to S Garrigue.

9 recordsLinked to original sources
PubMed1998

Spontaneous initiation of atrial fibrillation by ectopic beats originating in the pulmonary veins.

BACKGROUND: Atrial fibrillation, the most common sustained cardiac arrhythmia and a major cause of stroke, results from simultaneous reentrant wavelets. Its spontaneous initiation has not been studied. METHODS: We studied 45 patients with frequent episodes of atrial fibrillation (mean [+/-SD] duration, 344+/-326 minutes per 24 hours) refractory to drug therapy. The spontaneous initiation of atrial fibrillation was mapped with the use of multielectrode catheters designed to record the earliest electrical activity preceding the onset of atrial fibrillation and associated atrial ectopic beats. The accuracy of the mapping was confirmed by the abrupt disappearance of triggering atrial ectopic beats after ablation with local radio-frequency energy. RESULTS: A single point of origin of atrial ectopic beats was identified in 29 patients, two points of origin were identified in 9 patients, and three or four points of origin were identified in 7 patients, for a total of 69 ectopic foci. Three foci were in the right atrium, 1 in the posterior left atrium, and 65 (94 percent) in the pulmonary veins (31 in the left superior, 17 in the right superior, 11 in the left inferior, and 6 in the right inferior pulmonary vein). The earliest activation was found to have occurred 2 to 4 cm inside the veins, marked by a local depolarization preceding the atrial ectopic beats on the surface electrocardiogram by 106+/-24 msec. Atrial fibrillation was initiated by a sudden burst of rapid depolarizations (340 per minute). A local depolarization could also be recognized during sinus rhythm and abolished by radiofrequency ablation. During a follow-up period of 8+/-6 months after ablation, 28 patients (62 percent) had no recurrence of atrial fibrillation. CONCLUSIONS: The pulmonary veins are an important source of ectopic beats, initiating frequent paroxysms of atrial fibrillation. These foci respond to treatment with radio-frequency ablation.

Adolescent↗
PubMed1998

Scoring method for assessing rate adaptive pacemakers: application to two different activity sensors.

To optimize programming of rate adaptive pacemakers (RAPs), we explored a new mathematical method to assess the performance of RAPs during daily-life tests, using customized Windows-based software. By stepwise discriminant analysis and linear regression, this method allows calculation of the acceleration and deceleration capacity of pacemakers and their general behavior during effort and recovery phases. Twenty-three patients (10 females and 13 males; 68 +/- 8 years) with chronic atrial fibrillation and a slow ventricular response were evaluated. They randomly received an accelerometer-controlled VVIR Dash Intermedics pacemaker (10 patients) or a vibration piezoelectric-controlled VVIR Sensolog III Siemens pacemaker (13 patients). All patients underwent the same test protocol: 6 minutes walking, 1.5 minutes climbing stairs, 1.5 minutes descending stairs, and 0.5 minutes sit-ups. By definition, the pacemaker responsiveness slope was programmed so that the heart rate response of paced patients during the walking test corresponded best to that of healthy controls. The slope was left unchanged for the other tests. We considered four scores: an acceleration score (EA score), an effort rate score (ER score), a deceleration score (RD score), and a recovery rate score (RR score). Scores ranged from -10 (hypochronotropic behavior of the pacemaker) to +10 (hyperchronotropic behavior), based on daily-life tests of 15 healthy controls (7 females and 8 males, 65 +/- 9 years). A score of 0 represented exact concordance with healthy controls. During stair descent, the Sensolog III produced excessive acceleration (EA score = +2.9 +/- 1.1) compared to: (1) stair climbing (EA score = -4.0 +/- 1.9; P = 0.01, with the same pacemakers); and (2) the Dash (+1.8 +/- 1.9; P = 0.04) and healthy controls (P = 0.02). The sit-up tests revealed a hypochronotropic response of both pacemakers compared to healthy controls, with a larger difference for the Sensolog III (EA score = -2.0 +/- 5.8; P = 0.04; RD score = -6.8 +/- 3.8' P = 0.02). We conclude that activity-driven pacemakers can accommodate brief activities, except for isovolumetric exercise such as sit-ups. During daily activities, accelerometer-driven pacemakers seem to provide a heart rate resoibse closer to that of healthy controls. Our new mathematical analysis is a simple and reproducible method for evaluating and quantifying the efficacy of any sensor-driven pacemaker.

Adaptation, Physiological↗
PubMed1998

Circadian variations in minute ventilation can be reproduced by a pacemaker sensor.

Special software allowing the memorization of 24-hour minute ventilation can be loaded into the memory of the Chorus RM, a DDDR pacemaker driven by minute ventilation. This feature was tested in the postimplant period in 13 patients. Measurements of minute ventilation, respiratory rate, and respiratory amplitude were analyzed according to prospectively defined diurnal and nocturnal time periods. Minute ventilation decreased by 39% (P < 0.001) from the diurnal to the nocturnal phase, while respiratory rate and amplitude decreased by 18% and 28%, respectively (P < 0.001 each). Thus, minute ventilation allowed discrimination between sleep and waking hours. This information could be utilized to modulate the backup rate of the pacemaker.

Aged↗
PubMed1997

Three-dimensional mapping of the common atrial flutter circuit in the right atrium.

BACKGROUND: The full circuit of common atrial flutter using conventional methods of sequential or multielectrode activation mapping is not completely understood. METHODS AND RESULTS: We performed three-dimensional right atrial endocardial activation mapping during common counterclockwise atrial flutter in 17 patients (16 men, 1 woman; mean age, 53+/-11 years) by using the Cordis-Biosense EP Navigation system and assessed the distribution of estimated conduction velocities and double and fractionated potentials. ECG flutter wave morphologies were compared with activation patterns. Points (91+/-29) were sequentially acquired covering 88+/-11% of the flutter cycle length of 239+/-22 ms. A wide and variable posterior zone of double and fractionated potentials coincided with blocking and colliding wave fronts and formed the posterior limit of the circuit. A progressively widening septal (sep) wave front ascending from just beyond the coronary sinus ostium, passed cranially as a broad front anterior to the superior vena cava (SVC) in 14 patients, whereas fusion around the SVC formed the superior (sup) limb of the circuit in 3. Bounded anteriorly by the tricuspid valve, the wave front descended down the lateral (lat) aspect of the right atrium before completing the circuit in all cases through the inferior vena cava-tricuspid annulus isthmus. The estimated conduction velocity in the medial isthmus (0.6+/-0.3 m/s) was lower than in the other limbs of the circuit (sup=1+/-0.5 m/s, lat=1+/-0.5 m/s, sep=0.9+/-0.4 m/s, P=.05). Double and fractionated potentials were constant and more prevalent in the posterior right atrium. ECG flutter wave morphology did not correlate with three-dimensional activation maps. CONCLUSIONS: Interindividual variations occur in the right atrial circuit of common atrial flutter, with constant activation through the cavotricuspid isthmus. A variable zone of block forms the posterior limit. Fusion around the SVC can occur, and ascending medial septal activation does not follow a consistent pattern.

Adult↗
PubMed1996

[Flecainide acetate].

Flecainide acetate is a powerful antiarrhythmic initially used to treat ventricular arrhythmias. Despite an excess mortality in this indication and in the presence of heart disease, flecainide remains a good antiarrhythmic for supraventricular tachycardias in a healthy heart.

Anti-Arrhythmia Agents↗
PubMed1996

[Incidence of atrial arrhythmia in patients with long term dual-chamber pacemakers. Contribution of the Holter function of pacemakers].

The extension of the RAM memories in the latest generation of pacemakers has enabled development of Holter function allowing continuous surveillance of the cardiac rhythm. Between October 1991 and February 1995, 213 patients implanted with a Chorus 6234 or 7034 (Ela Medical) pacemaker, functioning in the DDD (R) mode, were followed up using the implanted continuous Holter function. Of the patients with no documented supraventricular arrhythmia (SVA) before implantation (n = 154), 67 (43.5%) developed SVA during an average period of one year. Male patients (p = 0.01; OR = 7.5 on multivariate analysis), high degrees of AVB (p = 0.03) and the presence of isolated or bursts of atrial extrasystoles (p = 0.004) were independent risk factors for SVA. The average time to detection of SVA was 207 days. In patients with documented SVA before implantation (n = 59), 22 (37.3%) had no recurrence during follow-up; in the other 37 cases, the average period before recurrence was 127 days. Multivariate analysis did not reveal any independent risk factor for recurrence of the arrhythmias. On the other hand, persistent but delayed atrioventricular conduction (1 degree AVB, long H-V interval or bifascicular block), seemed to protect against SVA, independently of other variables and of antiarrhythmic therapy (p = 0.008). These results suggest a high prevalence of SVA in patients on long-term pacemaker therapy, most episodes being asymptomatic. The implanted Holter function would therefore seem to be an essential tool for investigating and following up the natural history of arrhythmias in these patients.

Aged↗
PubMed1995

Assessment of non-invasive new imaging techniques in the diagnosis of heart liposarcoma.

Two patients, with recurrent acute pericarditis as the first presentation of liposarcoma, were admitted to our department between August and December 1992. The pericarditis was pericardial in one case and retroperitoneal with pericardial inflammation in the other. In contrast to most reported cases, where diagnosis was made post-mortem, diagnosis and surgical decision were based on non-invasive imaging techniques, without cardiac angiography. In cases of recurrent acute pericarditis resistant to usual drugs, new imaging techniques, such as computed tomodensitometry and magnetic resonance imaging, can detect rare causes such as liposarcomas in which prognosis is critically dependent on early diagnosis.

Acute Disease↗
PubMed1995

[Practical experience of specific catheter ablation of atrial flutter in 110 patients].

The object of this study was to assess the efficacy and risks of radiofrequency ablation of common atrial flutter and to determine the optimal site of ablation in a large population of patients. Three different methods were used to determine the site of ablation: the first was anatomical and electrophysiological whilst the two others were based essentially on anatomical landmarks for localising the critical zone of the reentry circuit. Recent studies report that radiofrequency ablation is effective in interrupting and preventing recurrences of common atrial flutter both by using anatomical and electrophysiological methods. Nevertheless, a larger series of patients was necessary to establish the efficacy and to determine the optimal site of ablation. A series of 110 consecutive patients with common atrial flutter resistant to antiarrhythmic drugs was studied. The site of ablation of the first 50 patients was determined using both anatomical landmarks and electrophysiological parameters. The anatomical zones were: zone 1, between the septal leaflet of the tricuspid valve and the orifice of the inferior vena cava; zone 2, between the septal leaflet of the tricuspid valve and the ostium of the coronary sinus, and zone 3: between the orifice of the inferior vena cava and the ostium of the coronary sinus. The electrophysiological criterion was an endocavitary auriculogramme occurring during the plateau phase preceding the F wave of the flutter.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗