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Biomedical subjects

S Cazeau

Publications and source records attributed to S Cazeau.

At least 19 recordsLinked to original sources
PubMed1998

Acute hemodynamic effects of biventricular DDD pacing in patients with end-stage heart failure.

OBJECTIVES: The aim of this study was to assess the potential acute benefit of multisite cardiac pacing with optimized atrioventricular synchrony and simultaneous biventricular pacing in patients with drug-refractory congestive heart failure (CHF). BACKGROUND: Prognosis and quality of life in severe CHF are poor. Various nonpharmacological therapies have been evaluated but are restricted in their effectiveness and applications. In the early 1990s, dual chamber pacing (DDD) pacing was proposed as primary treatment of refractory CHF but results were controversial. Recently, tests to evaluate the effect of simultaneous pacing of both ventricles have elicited a significant improvement of cardiac performance. METHODS: Acute hemodynamic study was conducted in 18 patients with severe CHF (New York Heart Association class III and IV) and major intraventricular conduction block (IVCB) (QRS duration = 170+/-37 ms). Using a Swan-Ganz catheter, pulmonary artery pressure, pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were measured in different pacing configurations: atrial pacing (AAI) mode, used as reference, single-site right ventricular DDD pacing and biventricular pacing with the right ventricular lead placed either at the apex or at the outflow tract. RESULTS: The CI was significantly increased by biventricular pacing in comparison with AAI or right ventricular (RV). DDD pacing (2.7+/-0.7 vs. 2+/-0.5 and 2.4+/-0.6 l/min/m2, p < 0.001). The PCWP also decreased significantly during biventricular pacing, compared with AAI (22+/-8 vs. 27+/-9 mm Hg; p < 0.001). CONCLUSIONS: This acute hemodynamic study demonstrated that biventricular DDD pacing may significantly improve cardiac performance in patients with IVCB and with severe heart failure, in comparison with intrinsic conduction and single-site RV DDD pacing.

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PubMed1998

Reliability of an automatic sensing test with beat-to-beat display of the signal amplitude.

In contrast to testing of the capture threshold, the reliability of sensing tests has been little studied. This study was performed to test the automatic sensing algorithm included in the Biotronik pacing systems. The automatic measurements made by the devices were compared with the direct manual measurements made of 271 atrial (72%) or ventricular (28%) electrograms recorded in ten patients. A high correlation (r = 0.995, P < 0.0001) was found between the two types of measurements. The use of this function should facilitate the verification of accurate sensing during the long-term follow-up of pacemaker patients, and offers a tool to analyze the variations in amplitude of intracardiac signals.

Algorithms↗
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.

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PubMed1998

Prevention of atrial arrhythmias during DDD pacing by atrial overdrive.

We evaluated the effect of atrial overdrive on the incidence of atrial arrhythmias (AA) in 22 patients (67 +/- 9 years, 7 women, 15 men) with Chorus 6234 DDD pacemakers. Atrial overdrive was defined as a programmed paced rate 10 ppm faster than the mean ventricular rate stored for the last 24-hour period in the pacemaker memory. The protocol consisted of three phases of 1 month each. Phase I: observation after discontinuation of antiarrhythmic therapy. Phase II: arrhythmia analysis using the pacemaker memory after programming the lower rate to 55 ppm. The fallback function and histogram data were used to document the number and maximal duration of AA episodes as well as the total AA time in a month. Phase III: atrial overdrive. The mean ventricular heart rate was 65 +/- 4 beats/min before atrial overdrive versus 75 +/- 5 with atrial overdrive (P = 0.02). At the end of phase II, all patients presented with AA episodes (mean number per patient: 42 +/- 78 in one month). In phase III (with atrial overdrive), 14 (64.6%) patients had no recorded AA (group A). In the other eight patients with persistent AA episodes in phase III (group B), there was a significant reduction in the number of AA episodes (90 +/- 106 in phase II vs 38 +/- 87 in phase III; P = 0.01), their total duration (166 +/- 115 in phase II vs 92 +/- 134 hours in phase III; P = 0.03) and their maximal duration (121 +/- 103 in phase II vs 85 +/- 89 min; P = 0.04). Our short-term data suggest that atrial overdrive prevents or reduces AA episodes and demonstrate the feasibility and need of long-term studies to determine whether this benefit is sustained.

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PubMed1998

Permanent left ventricular pacing with transvenous leads inserted into the coronary veins.

This paper describes a preliminary experiment-conducted jointly by 2 centers-of permanent left ventricular pacing using leads inserted by the transvenous route and through the coronary sinus into the cardiac veins of the left ventricle free wall. The aim was to obtain permanent biventricular pacing in a totally endocavitary configuration in patients with severe LV dysfunction and drug-refractory heart failure. Two types of leads were used: nonspecific unipolar leads at the beginning of the experiment, followed by leads specifically designed to be used in the coronary sinus in a second step. The electrode could be fitted in an adequate location in 35 of the 47 patients (75.4%), with a 1.15 +/- 0.7 V acute pacing threshold and 11.8 +/- 5.7 mV R wave amplitude. The success rate was significantly higher with the specific electrodes (81.8% vs 53.3%, p < 0.001). The pacing and sensing thresholds upon implantation were not influenced by the type of lead or by the localization of the cardiac vein that was catheterized (great cardiac vein, lateral vein, postero-lateral or posterior vein, mid cardiac vein). In contrast, the pacing threshold was significantly lower (0.8 +/- 0.2 vs 1.8 +/- 0.8 V; p = 0.002) and the R wave amplitude tended to be greater (13.1 +/- 4.5 mV vs 9.3 +/- 6.5 mV; p = 0.07) when the tip electrode could be inserted distally into the vein, by comparison with a proximal site near the ostium. At the end of follow-up (10.2 +/- 8.7 months), 34 out of the 35 leads were still fully functional, with a chronic pacing threshold of 1.8 +/- 0.7 V and a R wave amplitude of 10.7 +/- 6 mV. To conclude, permanent LV pacing via the transvenous route is possible in most patients, with excellent safety and long-term results.

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PubMed1998

Reduction in energy pacing thresholds by overlapping biphasic stimulation versus conventional bipolar pacing.

UNLABELLED: Overlapping biphasic (OLBI) stimulation is a new pacing waveform consisting of two simultaneous monophasic pulses of opposite polarities applied to a bipolar electrode. The goal of this prospective study was to compare, using conventional pacing leads, the acute energy pacing thresholds, measured at 0.5-ms pulse duration, associated with bipolar versus OLBI (mode 7 and mode 8) pulse delivery. RESULTS: Thirty one leads were tested in 20 patients. Of these leads, 7 (23%) were implanted chronically, 12 (39%) were in atrial positions, and 19 (61%) in ventricular positions. Energy pacing thresholds were significantly lower (-25.6 +/- 25.6%, P = 0.005) in OLBI mode 8 (1.30 +/- 3.96 microJ) compared to bipolar (1.55 +/- 4.37 microJ) pacing, regardless of the pacing site or length of service of the leads. In contrast, OLBI mode 7, which has an anodal component, at the tip electrode was associated with higher energy pacing thresholds (3.65 +/- 6.48 microJ; +358.3 +/- 219.4%, P = 0.002). CONCLUSIONS: Mode 8 OLBI pacing is associated with lower acute energy pacing thresholds when used with bipolar leads in contact with the myocardium. OLBI pacing may increase pacemaker longevity by reducing long-term energy consumption.

Arrhythmias, Cardiac↗
PubMed1998

Evaluation of a dual sensor rate responsive pacing system based on a new concept. French Talent DR Pacemaker Investigators.

The minute ventilation is known to be one of the most physiological indicators of exercise. A curvilinear relationship between VE and the normal sinus rhythm (NSR) has been demonstrated in healthy patients. The aim of this study is to show that a pacemaker based on a VE sensor can reproduce such a relationship. Eighty-one patients received a Talent DR 213 (ELA Medical, Montrouge, France) pacemaker with a third-generation rate responsive algorithm. At 1-month follow-up, the patients underwent a treadmill exercise test, after which three groups were defined: group 1 had 6 patients who were 100% paced throughout the exercise test; group 2 had 10 patients who maintained NSR throughout the test; and group 3 had 12 patients who had cardiopulmonary recording during the exercise test. In group 1 patients, the simulation function computed the simulated rate (sim-rate), which was compared to the sensor-driven rate (SDR). In group 2 patients, sim-rate was compared to the NSR. In group 3 patients, cardiac and metabolic reserves were compared to determine the appropriateness of the rate response to exercise (HRR% vs MR%). The results showed that the mean correlation coefficient between sim-rate and SDR was 0.983 +/- 0.005 (P < 0.001); the mean correlation coefficient between NSR and SDR was 0.92 +/- 0.07 (P < 0.001); and a linear relationship was found between HRR% and MR%, with a mean slope of 1.1 +/- 0.2 that was significantly equal to the theoretical value of 1 (P = NS). In conclusion, combining an activity-driven sensor with a physiological sensor allows the preservation of a physiological rate response during exercise.

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PubMed1998

[Pacing and heart failure].

Conventional dual-chamber cardiac pacing with the right ventricular pacing catheter positioned at the apex of the right ventricle was proposed eight years ago by Hochleitner as primary treatment of refractory cardiac failure. Although the preliminary results were encouraging, those at long-term and subsequent studies were less favourable in this indication. Biventricular pacing is now a technical possibility and allows at least partial correction of the electromechanical abnormalities observed in dilated cardiomyopathy. The preliminary results of biventricular pacing in patients with refractory cardiac failure due to dilated cardiomyopathy with major intraventricular conduction defects are very encouraging. This new therapeutic approach should now be validated by controlled, randomised therapeutic trials.

Cardiac Catheterization↗
PubMed1997

Value of automatic processing and reliability of stored data in an implanted pacemaker: initial results in 59 patients.

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.

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PubMed1996

Mode switch despite undersensing of atrial fibrillation in DDD pacing.

UNLABELLED: Mode switching algorithms are commonly used to protect the ventricles against high rates induced by atrial tachycardia. In the case of atrial fibrillation (AF), the response of these algorithms depends on the quality of atrial sensing. The Chorum 7234 DDDR pacemaker uses a new mode switching algorithm, based on a statistical analysis of the atrial rhythm. It includes two criteria of diagnosis: "high" if more than 28 of 32 cycles are abnormally accelerated; and "low" if more than 36 of 64 cycles are abnormally accelerated. METHODS: From a taped database of electrophysiological studies, episodes of AF lasting more than 2 minutes were selected. A tape recorder replayed the atrial signals into an external Chorum device. Each episode was replayed eight times with a programmed atrial sensitivity increasing from 0.4-2.0 mV. For each criterion of diagnosis and each programmed sensitivity, the percentage of atrial sensing, the time to switching, and the mean ventricular rate were measured. Ten episodes of AF from 10 patients (9 men and 1 woman; ages 62 +/- 16 years) were included: 1.95 +/- 0.97 mV and 196 +/- 64 ms. The sensitivity of the algorithm to diagnose atrial tachycardia reached 100%, for an atrial sensitivity set between 0.4 and 1.0 mV. The mean percentages of atrial sensed events were 74% +/- 18% and 46% +/- 9% for the "high" and "low" criteria, respectively. The mean diagnostic times were 28 +/- 26 seconds and 68 +/- 27 seconds, respectively. Sensing of < 23% of AF events resulted in failure to diagnose the arrhythmias by both algorithms. In the event of diagnostic failure, the mean ventricular pacing rate was 79 +/- 9 ppm. CONCLUSION: Up to an atrial sensitivity of 1 mV, 100% of AF episodes were diagnosed. The Chorum mode switching algorithms are 100% reliable if > 45% of the AF waves are sensed. In the event of switching failure, the ventricle is protected by an average rate remaining below 80 ppm.

Acceleration↗
PubMed1996

Ventricular protection against atrial arrhythmias in DDD pacing based on a statistical approach: clinical results.

Atrial arrhythmias (AA) are commonly encountered in DDD paced patients. Newer dual chamber pacemakers (PM) possess mode switching functions that convert pacing to an asynchronous mode when AAs are detected. The lack of a reliable mode switch leading to rapid, irregular ventricular responses may result from AA undersensing. To avoid this the DDDR PM Chorum 7234 Ela Medical AA diagnosis is based on a statistical approach: the PM constantly compares arrhythmic and sinus cycles and, based on "strong" and "weak" criteria, provides for rapid or slower mode switch. The aim of the study was to evaluate the efficiency and reliability of these two criteria. Thirty-one patients with a Chorum 7234 implanted for AV block (11), sinus dysfunction (10), both (5), or hypertrophic obstructive cardiomyopathy (5) were evaluated at 24 hours and 1 month using the internal memory (IM) of the PM, surface 24-hour Holter recordings, and exercise testing. Interrogation of the IM on the first day of study showed that 8 patients had mode switching episodes, based only on the strong criterion confirmed by the surface Holter recording. At 1 month, the IM revealed mode switching episodes in 12 patients, 6 of whom had used the weak criterion. No inappropriate mode switching episodes was recorded during exercise testing at the 1-month follow-up. These results confirm the reliability and efficiency of this algorithm as well as the requirement for a specific algorithm to compensate for transient loss of sensing during AA.

Algorithms↗
PubMed1996

Multisite pacing for end-stage heart failure: early experience.

Our objective was to improve hemodynamics by synchronous right and left site ventricular pacing in patients with severe congestive heart failure (CHF). Previous studies reported a benefit of dual chamber pacing with a short AV delay in patients with severe CHF. Other works, however, show contradictory results. Deleterious effects due to a desynchronization of right (RV) and left ventricular (LV) contractions have been suggested. This study included eight subjects with widened QRS and end-stage heart failure despite maximal medical therapy, who refused, or were not eligible to undergo heart transplantation, Each patient underwent a baseline, invasive hemodynamic evaluation with insertion of three temporary leads to allow different pacing configurations, including RV apex and outflow tract pacing, and biventricular pacing between the RV outflow tract and LV and RV apex and LV. According to the results of this baseline study, the configuration of preexistent pacemakers was modified or new systems were implanted to allow biventricular pacing, which, in patients with sinus rhythm, was atrial triggered. Biventricular pacing increased the mean cardiac index (CI) by 25% (from a baseline of 1.83 +/- 0.30 L/min per m2, P < 0.006), decreased the mean V wave by 26% (from a baseline of 36 +/- 12 mmHg, P < 0.004), and decreased pulmonary capillary wedge pressure by 17% (from a baseline of 31 +/- 10 mmHg, P < 0.01). Four patients died (1 preoperatively, 1 intraoperatively, 2 within 3 months, and 1 of a noncardiac cause). The four surviving patients have clinically improved from New York Heart Association Functional Class IV to Class II. In these survivors, CI decreased by 15% (P < 0.007) when multisite pacing was turned off during follow-up. In patients with end-stage heart failure, multisite pacing may be associated with a rapid and sustained hemodynamic improvement.

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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.

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PubMed1996

[First experience in treatment of terminal cardiac insufficiency using multisite stimulation].

We hypothesized that the presence of an abnormal ventricular mechanical activation sequence and/or a delayed left ventricular (LV) contraction may have adverse hemodynamic effects in congestive heart failure (CHF) and could be improved by synchronous RV-LV pacing in a multisite (MS) configuration. 8 NYHA IV CHF patients were included with a LV delay due to 1/ preexistent pacemaker in 4 pts (2 VVI and 2 DDD); 2/ left bundle branch block in 2 pts; 3/ intraventricular conduction delays in 2 pts. An acute hemodynamic evaluation was performed. Hemodynamics were optimized in standard RV pacing by modifying RV lead position from apex to outflow tract (RVOT) in VVI for AF patients and in VDD for sinus rhythm patients at different AV delays. RV pacing did not change hemodynamics whatever the lead position. BV pacing improved CI by 25% (p < 0.006), V wave by 26% (p < 0.004) and PCWP by 17% (p < 0.01). Chronic implantation was performed in 7pts. LV lead was implanted via the coronary sinus in 2 cases and epicardial via a thoracoscopic approach in the remaining ones. 1 pt died during LV lead implantation. Hemodynamics were tested at 2 months followup (FU). Switching BV pacing off was associated with immediate deterioration. At 6 +/- 6 months Followup 4 pts are stable in Class II. 1 pt died of cardiac cause. 1 pt could be transplanted at 17 months FU. In conclusion, BV pacing through a multisite configuration is feasible and can help in CHF patients managing.

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PubMed1995

Carotid sinus syndrome: acute hemodynamic evaluation of a dual chamber pacing mode.

Cardiac pacing is the treatment of choice in patients with carotid sinus syndrome (CSS). Three different pacing modes were tested in 20 patients (16 males, 4 females; mean age 75 +/- 9 years) with documented symptomatic CSS. Three carotid sinus massages (CSM) were performed in each supine patient successively paced in random order in: DDI--the reference pacing mode; DDD--automatic mode conversion (DDD/AMC) allowing automatic switching from AAI to DDD when AV block occurs; DDD/AMC plus atrial acceleration (DDD/AMC+acc); and OOO (CSM without pacing) to determine whether the vasodepressive effect was still present 10 minutes after the preceding CSM. Intraarterial blood pressure was continuously monitored. Results were expressed as the value of the mean systolic BP at T0 + 3 s + 6 s ... T0 + 30 s divided by the value of the mean systolic blood pressure prior to onset of CSM. The drop in arterial blood pressure was more severe in the DDI mode than in DDD/AMC (P < 0.001) and DDD/AMC+acc (P < 0.0001) in 20 patients. In the OOO mode, the drop in arterial blood pressure was most marked and greater than in the DDI mode (P < 0.0001). The average time between start of the CSM and onset of the drop in blood pressure was the same in the three dual chamber modes. We conclude that the DDD/AMC mode significantly improves the vasodepressor response to CSM compared to the DDI mode. There is a current trend favoring DDD/AMC+acc over DDD/AMC.

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PubMed1995

Preliminary evaluation of a dual chamber pacemaker with bradycardia diagnostic functions.

Unexplained syncope is the main indication for the implantation of a diagnostic pacemaker. Studies on those implanted have shown that in patients with unexplained syncope, the diagnosis of paroxysmal bradycardia was feasible and reliable. The present study was designed to evaluate a new bradycardia diagnosis algorithm, loaded in a dual chamber pacemaker, in 24 patients considered as candidates for diagnostic pacemakers. During a mean follow-up of 153 days, at least one bradycardia episode was recorded in 13 patients. The mean number of detected bradycardias was 6 and the median was 3. The mean delay between the algorithm activation and the first bradycardia episode was 67 days. The mechanism of bradycardia was atrioventricular block in 6 patients, sinus node dysfunction in 6 patients, and consecutive blocked atrial premature beats in 1 patient, as indicated by the event markers. In 11 patients bradycardia was recorded during the daytime only or day and night. In two patients the episodes were recorded only at night. Overall, the algorithm was well-tolerated; however, some mild symptoms were observed due to the method of bradycardia determination, allowing bradycardia. Three patients were symptomatic as a direct result of the algorithm operation, and four patients had symptoms related to the single chamber operation of the pacemaker while functioning in the diagnosis mode (VDI). These symptoms were relieved with DDD pacing.

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