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Biomedical subjects

C Daubert

Publications and source records attributed to C Daubert.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Importance of atrioventricular synchrony in hypertrophic obstructive cardiomyopathy treated by cardiac pacing].

This study was undertaken to evaluate the effect of permanent dual-chamber cardiac pacing in hypertrophic obstructive cardiomyopathy resistant to medication, paying particular attention to atrioventricular synchrony. Sixteen patients, mean age 59 +/- 13 years (range 36 to 80 years) were divided into two groups after in initial catheter study performed under temporary VDD pacing between March 1990 and April 1993. In group I (n = 11), the gradient was decreased by more than 50% whereas in group II (n = 5), the gradient was unchanged or reduced by less than 50%. The reduction of the gradient was immediately significant in group I, the mean value falling from 104 +/- 33 mmHg (range 60 to 170 mmHg) to 25 +/- 13 mmHg (range 10 to 60 mmHg) (p < 0.0001). In group II, the gradient only decreased initially from 132 +/- 13 mmHg (range 120 to 150 mmHg) to 88 +/- 25 mmHg (range 50 to 130 mmHg) (p < 0.003) but improved atrioventricular synchrony, obtained secondarily either by pharmacological prolongation of the PR interval (association of betablocker and verapamil) or by ablation of the atrioventricular junction, improved the haemodynamic benefits. The residual gradient recorded on the 7th day was only 26 +/- 15 mmHg (range 10 to 50 mmHg) (p < 0.0001). The comparison of the two populations showed that the mean PR interval was shorter in group II (p < 0.016) and the mean value of the optimal AV Delay (the longest AV Delay with complete ventricular capture) was also lower (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1995

[Value of cardiac pacing in hypertrophic obstructive cardiomyopathy refractory to medical treatment].

Recent studies have shown that dual-chamber cardiac pacing could improve patients with hypertrophic obstructive cardiomyopathy resistant to medical treatment. After a brief historical review, the authors report the present status of this original therapeutic option. The results of different studies are in agreement and show that the functional improvement is associated with a large reduction of the intraventricular pressure gradient with permanent DDD pacing. Although the exact mechanism of the improvement remains unknown, all groups underline the importance of complete and permanent ventricular capture. This requires precise regulation of the atrioventricular delay which in most cases must be programmed at a value inferior to 90 ms, which compromises ventricular filling which is already abnormal under basal conditions. The inefficacy of pacing in some cases is explained by the necessity of selecting a very short atrioventricular delay which alters diastolic function and finally masks the benefits of ventricular capture. In this particular situation, the authors propose improving atrioventricular synchrony by pharmacological prolongation of the PR interval, or, when unsuccessful, by ablation of the atrioventricular junction. This attitude was adopted in 5 cases when pacing with an AVD programmed between 20 and 70 ms, provided only a partial haemodynamic result. Improved atrioventricular synchrony allowed selection of an AVD of 100 to 150 ms, so reducing the gradient by more than 70%, compared with 30% under the initial programming parameters. The authors conclude that a positive and sustained benefit of cardiac pacing can only be obtained by an individualised regulation of pacing parameters to optimize atrioventricular synchrony which seems to be the key element of success.

Adrenergic beta-Antagonists↗
PubMed1995

[The esophageal approach in rhythmology].

The possibility of detecting the electrical activity of the heart from the oesophageus has been recognised for nearly a century. On the other hand, transesophageal pacing has only been really developped in the last fifteen years, which explains the recent interest for this technique in clinical practice. Easily put into practice, but not always well tolerated, the oesophageal approach has many uses in rhythmology. The principal diagnostic applications are in unlabelled tachycardias whether with narrow or wide QRS complexes, the evaluation of the Wolff-Parkinson-White syndrome, the study of sinus node function or nodal conduction. The therapeutic applications are dominated by the reduction of supraventricular tachycardias especially atrial flutter, with a success rate similar to that of endocavitary stimulation. The facility of realisation, especially at the patient's bedside, without need for fluoroscopie control, makes it a useful tool in emergencies, especially if the endocavitary approach cannot be used. The only reserve is the painful character of pacing in some patients.

Anti-Arrhythmia Agents↗
PubMed1995

[Infections on permanent endocavitary pacemaker leads: value of transesophageal echocardiography].

The prevalence of infection of permanent pacing material ranges from 0.13 to 19.9% of patients according to published series. The seriousness of this condition requires early diagnosis and treatment. Transesophageal echocardiography visualised vegetations on the intracardiac pacing lead in all of 11 patients studied, whereas transthoracic echocardiography and polynuclear leucocyte scintigraphy only provided positive diagnoses in 4 cases for each investigation. Three types of vegetation were visualised; no cases of tricuspid valve endocarditis were observed. Treatment was based on explantation of all implanted material by endovascular traction in 7 cases and by surgery in the other 4 cases according to the results of transesophageal echocardiography. There were no deaths or recurrence of infection. Transesophageal echocardiography is the investigation of choice for imaging a vegetation on an endocavitary pacing lead. Complete explanation is essential for a complete recovery of this infection.

Adult↗
PubMed1994

[Permanent atrial resynchronization by synchronous bi-atrial pacing in the preventive treatment of atrial flutter associated with high degree interatrial block].

UNLABELLED: Interatrial conduction block results in a very delayed and retrograde activation of the left atrium and is associated with a high incidence of atrial tachyarrhythmias, especially a particular (and specific) form of atypical atrial flutter. Electrophysiologic studies have suggested that these arrhythmias were usually due to reentry and could be directly related to the conduction disturbances in the atrium. If so, we can expect reasonably that permanent atrial resynchronization resulting from simultaneous pacing in different target sites in the atria, may not only correct for interatrial dysynchrony, but also may significantly contribute to prevent arrhythmia recurrences. Twenty-eight patients, mean age 68 years, were included. The mean P wave duration in spontaneous sinus rhythm was 181 +/- 28 ms. In all patients, many recurrences of atrial tachyarrhythmia were documented, especially a specific form of atypical atrial flutter. Medical therapy was constantly ineffective. Three different pacing modes were used: 6 patients, with normal A-V conduction were implanted with a SSI device, programmed in AAT mode and connected, using a Y bifurcated connector, to two atrial leads, one positioned in the right atrium, the second one into the coronary sinus-in 14 patients, with A-V conduction defects, a conventional DDDR unit was implanted and connected to a composite biatrial electrode and a ventricular lead. In that configuration atrial resynchronization was only effective on paced atrial cycles -a specific DDD Chorus ELA Medical device with a special algorithm loaded into the RAM memory was implanted in 14 patients (8 new indications, and 6 patients first implanted with a DDDR unit). RESULTS: during sinus rhythm atrial resynchronization induced a reduction of the P wave duration from 181 +/- 28 ms to 116 +/- 12 ms. During permanent pacing the mean value decreased from 209 +/- 38 ms to 108 +/- 13 ms. During follow-up (34 +/- 15 months) arrhythmia prevention was assessed by history, by monthly surface ECG's and by bimonthly 24 hours Holters recordings and telemetric interrogation of the pacemaker statistics. Twenty-one patients did not experienced any recurrence of arrhythmia. One to three recurrences occurred in the other seven patients, including six patients implanted with a conventional DDDR unit. These preliminary results seem validate the new concept of atrial resynchronization for prevention of atrial arrhythmia associated with interatrial conduction block.

Adult↗
PubMed1993

Clinical role of d-sotalol and d,l-sotalol in supraventricular arrhythmias, including pre-excitation.

Numerous trials performed over the last 20 years, although uncontrolled, have shown the racemic d,l-sotalol is effective for the acute conversion and for long-term prevention of recurrences of supraventricular tachyarrhythmias. Sotalol appeared to be moderately effective in atrial fibrillation or atrial flutter, having somewhat greater efficacy in the case of atrioventricular (AV) nodal re-entrant tachycardia due to Wolff-Parkinson-White syndrome or concealed accessory pathway. These effects may stem from the combined class II and class III electrophysiologic properties of this drug. However, studies comparing d,l-sotalol to pure beta blockers in different 'models', especially postsurgical arrhythmias and Wolff-Parkinson-White syndrome, have suggested that the observed clinical benefit may be related to d,l-sotalol's class III properties. Thus, d-sotalol may be efficacious in these indications. Its precise efficacy should be defined in controlled clinical trials.

Adrenergic beta-Antagonists↗
PubMed1993

[Radiofrequency catheter ablation of accessory atrioventricular pathways: initial experience in 33 patients].

The authors report their experience in endocavitary radio-frequency ablation of 37 secondary pathways carried out in 33 consecutive patients. The indications for radical treatment were based solely on clinical arguments in 15 patients, on a combination of disabling signs and threatening electrophysiological signs in 17 patients and on high retrograde permeability in 1 asymptomatic patient. Endocavitary exploration revealed 26 left lateral sites, 7 posterior paraseptal sites and 4 right lateral sites. The procedure was successful in 88% of cases. Electrophysiological follow-up, carried out routinely in all the patients 2 months after the procedure, revealed a single recurrence (3%) which was treated by radio-frequency again, this time with a successful outcome. There was only one complication, a complete AVBBB following ablation of a left posterior paraseptal Kent's bundle, which required a permanent pacemaker. These results were similar to those reported in the literature and clearly demonstrate the efficacy of radio-frequency treatment of the secondary pathways, with a moderate risk of complication. These results were similar to those reported in the literature and clearly demonstrate the efficacy of radio-frequency treatment of the secondary pathways, with a moderate risk of complication. Recent advances in the field of endocavitary ablation have made it possible to change the method of handling symptomatic Wolff-Parkinson White syndromes, by enlarging the indications for radical treatment in order to enhance the comfort and quality of life of the patient.

Adolescent↗
PubMed1992

[Influence of exercise on the permeability of accessory pathways and supraventricular arrhythmia in Wolff-Parkinson-White syndrome].

The influence of adrenergic stimulation on the effective anterograde refractory period of the accessory pathways and on supraventricular arrhythmias, was studied in 20 patients (average age 38 +/- 16 years) with an untreated permanent Wolff-Parkinson-White syndrome and a resting anterograde refractory period < or = 400ms. Repeated electrophysiological studies with a single endocavity catheter positioned near the atrial pole of the accessory pathway were performed under basal conditions and during a standardised exercise test on a bicycle ergometer. The effective anterograde refractory period of the accessory pathway, the length of the tachycardia cycle during reciprocating orthodromic tachycardia, the average heart rate, the percentage of preexcited QRS complexes during induced atrial fibrillation, were measured in all patients under basal conditions and at the peak of exercise. Exercise significantly reduced the anterograde refractory period of the accessory pathway (287 +/- 49 ms at rest versus 238 +/- 24 ms on exercise: p < 0.001), the cycle of orthodromic tachycardia (302 +/- 32 vs 260 +/- 22 ms p < 0.001), the minimal R-R interval (270 +/- 65 vs 227 +/- 46 ms: p < 0.05) and % of preexcited QRS complexes (75 +/- 33 vs 51 +/- 39: p < 0.05) in atrial fibrillation whilst increasing the average heart rate (165 +/- 42 vs 202 +/- 39 bpm: p < 0.02). Adrenergic stimulation significantly improves anterograde conduction in the accessory pathway. The reduction in the % of preexcited QRS complexes in atrial fibrillation could indicate a preferential action of catecholamines on the nodo-hisian pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[Results of coronary-angiographic evaluation after endocavitary fulguration of the accessory pathways].

Left ventricular aid coronary angiography was performed systematically in 32 consecutive patients (average age 34 +/- 16 years) to assess the potential risk of coronary and myocardial lesions after high energy catheter ablation of an accessory pathway. The control was performed 2 to 6 months after the procedure in 30 patients and as an emergency immediately after the procedure in 2 patients because of prolonged ST segment elevation in 1 and an echocardiographic abnormality in the other. The catheter ablation was performed by a right heart approach in 19 patients and by retrograde catheterisation of the left heart in the other 13. The average number of shocks delivered was 3.6 +/- 2.4 in 1.8 +/- 1.2 session with an average energy of 632 +/- 220 joules. The global success rate was 88%, 70% complete successes and 18% clinical successes. The left ventricular and coronary angiographies were normal in 31 patients, including the 2 patients investigated as an emergency. On the other hand, one totally asymptomatic patient in whom a left lateral bundle of Kent had been ablated 2 months previously by a retrograde transaortic approach, had a large pseudo-aneurysm of the left ventricular posterior wall and coronary angiography showed a fistula between the first lateral branch of the circumflex artery and the left ventricle. At surgery, a localised rupture of the mitral annulus was confirmed. Two factors may at least partially explain this complication: the quantity of energy delivered (1,000 joules) in a single session to a limited area, and the site of ablation on the ventricular side of the mitral annulus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[Radiofrequency ablation of atrioventricular conduction during the 5th month of pregnancy].

The authors report the case of radiofrequency ablation of atrioventricular conduction in a 5 months pregnant woman who had hypertrophic cardiomyopathy. The indication of this procedure was a poorly tolerated resistant supraventricular tachycardia with foetal distress. A dual-chamber rate-assisted pacemaker programmed in the VVIR mode was implanted during the same procedure normally, with normal delivery of a healthy child at 8 months' gestation.

Adult↗
PubMed1992

[Long-term outcome of a hospital series of patients with atrio-ventricular accessory pathway].

Ninety five patients with a mean age of 39 +/- 19 years, 82 of whom were symptomatic, having an accessory atrioventricular bidirectional conduction pathway (WPW syndrome: 77; "concealed": 18) were followed up for an average of 7.3 +/- 2.6 years. The objectives were to analyse: the incidence and causes of death and the possible predictive factors of death due to the WPW syndrome--the influence of medical treatment and type of medication on survival and symptoms. Of the 8 cardiac deaths, 6 seemed to be related to the WPW syndrome, a prevalence of 7.8% and an annual incidence of 1.1/1000. The main risk factors which were identified were: age 62 +/- 8 years versus 37 +/- 15 years in survivors; p < 0.02--associated organic heart disease, especially ischaemic heart disease (5/6)--the description of severe symptoms, in particular recurrent syncope--documented malignant spontaneous or induced arrhythmias (5/6)--anterograde AV conduction with an effective refractory period < or = 230 msec in 4, though it was only 270 msec in the other 2 patients, indicating that this parameter is not specific--amiodarone (6/6) did not prevent the fatal outcome in this particular group of patients. In the "benign" forms, only betablocker drugs could significantly reduce the frequency and severity of symptoms, especially when compared with Class I or IC antiarrhythmics. These results suggest that the indications of radical treatment should be widened in high risk patients, especially when elderly and with associated coronary artery disease. They also suggest that the role of betablocker drugs should be reevaluated in the so-called "benign" symptomatic forms.

Adolescent↗
PubMed1992

[Doppler echocardiography and double chamber pacing].

Doppler-echocardiography is playing an increasing role in cardiac pacing: 1) Before implantation, to determine any cardiac disease possibly accompanying the conduction disturbance, and the quality of atrial function in order to identify the appropriate indications for the type of pacing which will restore normal AV synchronism. Alongside morphometric data (size of atria, etc.), this analysis is based above all on the evaluation of LV filling flows and ejection, if necessary during provisional pacing in DRV mode. It is important to be aware of and prevent certain problems: 1st degree AV block with very long PR, high degree interatrial conduction disturbances, etc. 2) To evaluate the possible benefits of pacing in certain new indications, e.g. obstructive hypertrophic cardiomyopathy (measurement of intra-LV gradient in sinus rhythm and with DRV pacing with total ventricular capture). 3) After implantation, to optimise the programming of double-chamber pacemakers and in particular AV intervals (base-line AV interval with paced atrial cycle, AV interval with detected atrial cycle, hysteresis of AV interval corresponding to the difference between the two previous values, slope of automatic variation in AV interval during exercise, etc.). Individual programming of these parameters based upon analysis of transmitral and ejection flow rates, at rest and, if necessary, during exercise, enables the optimisation of cardiac function (which is above all useful in the presence of concomitant organic heart disease) while at the same time improving the electrophysiological behaviour of the pacemaker at high frequencies.

Cardiac Pacing, Artificial↗
PubMed1992

[Value of an algorithm of automatic adaptation of the atrio-ventricular delay to the instantaneous atrial rate in cardiac stimulation].

It has been suggested that an algorithm of automatic adaptation of the AV delay to the instantaneous atrial rate be introduced into the program of DDD pacemakers to reproduce the physiological adaptation of the PR interval to effort, characterised by progressive shortening inversely linearly related to the heart rate. In order to evaluate the potential benefits in conditions of "standard" programming (basal AV delay the same for all patients: maximal frequency of 1/1 AV synchronisation uniformly limited to 120 bpm), a haemodynamic study was undertaken in 10 patients who had permanent DDD pacemakers implanted for advanced AV block. Measurements were taken during two standardized exercise stress tests (20 W/2 mn steps from an initial load of 20 W) performed in a random order, one with a fixed AV delay of 156 ms and the other with an "automatic AV delay" allowing linear reduction from a maximum value of 156 ms at rest to a minimum value of 84 ms at the maximum heart rate of 120 bpm. At the peak of exercise the "automatic AV delay" significantly affected 4 parameters: the paced ventricular rate (p = 0.008) and rate-pressure product (p = 0.005) which increased, pulmonary capillary pressure (p = 0.03) and cycle-to-cycle variability of systolic and diastolic blood pressures (p = 0.02 < p < 0.0001) which decreased. There was a tendency (NS) to slowing of the spontaneous atrial rate and to increase in cardiac output. This increase was significant in some patients and seemed to be due to a good relationship between the individual optimal value of the value basal AV delay measured by Doppler echocardiography and the value programmed in this study (156 ms).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Lack of physiological adaptation of the atrioventricular interval to heart rate in patients chronically paced in the AAIR mode.

Seventeen consecutive patients, aged 56 +/- 12, were chronically paced in the AAIR mode for a symptomatic sinus node disease with atrial chronotropic incompetence defined by a peak exercise heart rate (HR) less than 75% of the maximal predicted heart rate (MPHR) mean = 65 +/- 10%). Sensors used were activity sensing (n = 7), minute ventilation (n = 6), or respiratory rate (n = 4). Basic pacing rate was programmed at 71 +/- 5 beats/min and the maximal sensor rate at approximately 85% MPHR (143 +/- 10); other sensor parameters were programmed individually. Six months after implant, two standardized and symptom limited exercise tests were performed in random order, AAI and AAIR modes, respectively. AAIR pacing significantly improved peak exercise HR (139 +/- 14 vs 112 +/- 30 beats/min; P less than 0.01), maximal sustained workload (132 +/- 42 vs 110 +/- 38 watts; P less than 0.02), and total exercise duration (724 +/- 299 vs 594 +/- 245 sec; p less than 0.02) compared to the AAI mode. In all 17 patients, HR was continuously sensor driven in the AAIR mode, making it possible to precisely study the adaptation of the stimulus-R interval and of the stimulus-R:RR ratio during exercise. Six patients normally adapted with a progressive shortening. Six others did not adapt at all without any variation of interval. Five patients paradoxically increased their stimulus-R interval (286 +/- 10 msec at peak E vs 220 +/- 19 msec at rest) and their stimulus-R:RR ratio (67 +/- 20% vs 29 +/- 4%), producing P waves occurring immediately after, or even within the R wave of the preceding cycle; two patients complained of severe exercise related symptoms corresponding to the so-called "AAIR pacemaker syndrome." The principal factors involved in the nonadaptation of AV interval to HR were related to the patient (organic heart disease, with the particular problem of the denervated heart; the bradytachy syndrome; and the use of drugs, especially beta blockers and Class I antiarrhythmic drugs) or to the pacemaker ("overstimulation" phenomenon). These observations constitute an additional argument for wider indications of implanting DDDR units in these patients.

Adaptation, Physiological↗
PubMed1990

Dynamic electrophysiology of ventriculoatrial conduction: implications for DDD and DDDR pacing.

The behavior of ventriculoatrial conduction (VAC) during exercise remains unknown. In order to determine its characteristics and the consequences it might have on dual chamber pacemaker technology and programming, 17 patients underwent an electrophysiological study (EPS) of atrioventricular conduction (AVC) and of VAC during a protocol including three steps: supine rest, upright position, and finally during cycloergometric exercise; the measurements were done at progressively increasing pacing rates. During a preimplantation EPS, Wenckebach points AVC-W and VAC-W and conduction times, AVCT and VACT (as a function of pacing rate), were measured in ten consecutive patients using temporary leads and an external device. In another study, AVCT, VACT, AVC-W, and VAC-W were measured by telemetric recordings under identical conditions in seven patients implanted earlier with a DDD pacemaker. A 1/1 VAC was observed in 7/17 patients (41%) at rest, and in 13/17 patients (76%) at the end of the protocol; VAC was never observed in 4/17 patients (23%), but occurred in six of the ten patients initially free, three standing at rest and three on exercise. For all patients, the VAC behavior remained of "nodal" type, indicated by a progressive increase in VACT as pacing rate rose up to the VAC-W point. Neither the existence of exercise-induced VAC nor the maximal VACT-W could be predicted from AVC or VAC data obtained at rest. However, at the same pacing rates, standing up and exercise induced a shortening effect on VACT, and improved the VAC-W by an average of 33%. These results suggest that the electrophysiological behavior of VAC does not obey any general rule and cannot be predicted individually. It would thus appear unwise to base pacemaker mediated tachycardia (PMT) protection solely on long postventricular atrial refractory period (PVARP) programming in DDD patients. This work also revealed the potential risks of a rate responsive auto-adaptive PVARP algorithm as proposed in certain new devices.

Adult↗
PubMed1989

Benefits and limits of selective right ventricular cineangiography in arrhythmogenic right ventricular dysplasia.

Cineangiographic data from patients with probable arrhythmogenic right ventricular dysplasia (ARVD) were compared with those from matched controls. Some changes previously thought to indicate ARVD did not do so in this study. The abnormalities specific for ARVD were free wall morphological and wall motion abnormalities, particularly bulges and mamillated akinetic areas.

Adolescent↗
PubMed1989

Haemodynamic benefit of a rate-adapted A-V delay in dual chamber pacing.

In dual chamber pacing, an improvement of exercise capacity is expected when the atrial refractory period is shortened, because the 2/1 point is increased. This objective can be achieved by greatly reducing atrioventricular delay (AVD) on exercise. Are such variations (up to 100-120 ms) detrimental from a haemodynamic standpoint? This study was performed to analyse this particular aspect of DDD pacing. Three DDD pacing modes, differing by their AVDs (fixed 200 ms AVD, fixed 150 ms AVD, and rate-adapted AVD) were tested in random order, with a haemodynamic protocol including ten patients with chronic atrio-ventricular (A-V) block. For the rate-adapted AVD pacing mode, AVD was reduced by 20 ms every 10 beats min-1 increment (from 220 ms at 90 beats min-1 to 100 ms at 150 beats min-1). Pacing rate was increased from 90 to 150 beats min-1 by increments of 10 beats min-1 every 5 min. Cardiac performance was significantly improved with the rate-adapted AVD above the two fixed AVDs, despite a large AVD variation. When AVD was rate adapted, cardiac index, stroke volume index and left ventricular systolic work index were generally higher and pulmonary capillary wedge pressure, pulmonary arterial pressure and systemic vascular resistances were generally lower, especially at 120, 130 and 140 beats min-1. Comparing the two fixed AVDs, 200 AVD improved cardiac function more at lower heart rates, whereas 150 AVD improved cardiac function more at higher heart rates. Despite its limitations, this study demonstrates that the potential benefits of reducing AVD with increasing heart rates should be twofold in dual chamber pacing: (a) haemodynamic, optimizing cardiac performance on exercise for all heart rates, especially in cases of organic heart disease; (b) electrophysiologic, permitting a sufficiently rapid maximal tracking rate in cases with long post-ventricular atrial refractory periods, allowing a satisfactory level of exercise.

Aged↗