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C Cabanis

Publications and source records attributed to C Cabanis.

18 recordsLinked to original sources
PubMed1992

[Percutaneous ablation of atrioventricular junction by radiofrequency current in resistant atrial arrhythmia. Results of a series of 24 patients].

Catheter ablation of the atrioventricular junction may be proposed for the treatment of certain atrial arrhythmias resistant to antiarrhythmic therapy. One of the methods currently being evaluated uses radio-frequency energy which has certain advantages compared with direct current ablation because of the progressive and limited lesions it produces. This technique was used in 24 patients with atrial arrhythmias resistant to antiarrhythmic therapy. The radio-frequency energy was delivered without general anaesthesia with HAT 100 and 200 (OSYPKA) generators in the unipolar mode (average 17.4 watts) for an average period of 22.3 +/- 8 seconds. The catheter (8F USCI suction catheter in the first 18 patients and a 7F Polaris Mansfield, deflectable catheter with a large distal electrode in the remainder) was positioned at the nodo-hisian junction at a point where the two distal electrodes recorded a large atrial deflection and the smallest possible hisian potential. The conduction defects induced during the acute phase generally remain stable in cases of complete atrioventricular block and tend to regress in cases of incomplete atrioventricular block despite initial control of atrioventricular conduction. During follow-up (21 +/- 16 months), 14 patients (58%) remained in complete atrioventricular block, 4 patients (17%) had controlled atrioventricular conduction with an acceptable ventricular rate with associated previously ineffective antiarrhythmic therapy. Radio-frequency ablation was a failure in 6 patients (25%). There were no haemodynamic, rhythmic or ischaemic complications during the acute phase or during follow-up. These results suggest radio-frequency energy is a seductive alternative to direct current ablation for percutaneous modification of atrioventricular conduction in patients with refractory atrial arrhythmias. However, simple modulation of atrioventricular conduction gives aleatory results due to the tendency to regression during follow-up. On the other hand, complete atrioventricular blocks created by radio-frequency energy are generally definitive and are associated with a junctional escape rhythm which is usually stable.

Adult↗
PubMed1990

[Physiopathology of the sinus node and sinoatrial conduction].

New information about the pathophysiology of the sinus node and sino-atrial conduction has been published in the last few years. The sinus node consists of cells separated by a network of collagen fibres. This anatomical disparity explains the different electrophysiological characteristics of the node; the morphology of cellular action potentials depends on the site of recording. The dominant and most automatic pacemaker cells are situated in the cephalic region and the latent pacemaker cells in the caudal region. However, synchronisation of these different cellular activities is possible and results in a coherent signal. This complex synchronisation has been the object of several recent papers. The phenomenon of intrasinusal pacemaker shift and the stimuli which induce it have been studied in depth. In general, positive chronotropic stimuli tend to shift the dominant pacemaker towards the cephalic part and negative chronotropic stimuli towards the caudal part of the node. It is possible to assess pacemaker shift clinically and this phenomenon must be taken into consideration when studying sinus node function. Intercellular conduction and especially electrotonic conduction does not play a role in the genesis of the flux, which represents spontaneous cellular automatism, but in its mode of expression, that is to say the sinus rhythm. The pathophysiology of sinoatrial block is complex because it may be situated within and/or around the sinus node. The extrinsic or intrinsic mechanisms of these blocks may be interrelated. Variations in sinus rhythm must be taken into account in the genesis of sinoatrial block; an acceleration in rhythm may block conduction in the perisinusal region. Finally, our knowledge of the ionic fluxes underlying sinus automatism has also improved with individualization of the pacemaker current (if).(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1985

[Clinical and electrophysiological aspects of median intra-His bundle block with normal electrocardiogram at rest].

The clinical and electrophysiological features and the natural history of median intra-His block with a normal resting electrocardiogram were studied: 11 patients had a fixed split H1-H2 potential with a spontaneous or induced block between H1 and H2. The patients (5 men and 6 women) were aged 17 to 70 years (average 53 years). Associated pathology included 2 cases of aortic stenosis (1 severe), 1 case of ischaemic heart disease (effort angina), 1 case of mitral valve prolapse and 2 cases of hypertension. The presenting symptoms were syncope (4 cases), dizziness (2 cases), effort angina (1 case) and tiredness (3 cases); 1 patient was asymptomatic. Holter monitoring (24 hours) was performed in 8 patients and s-owed paroxysmal conduction defects in 6 cases; 4 Mobitz II 2nd degree AV block, 1 3rd degree AV block with narrow QRS complexes and 1 case of blocked atrial extrasystoles at coupling intervals longer than 480 ms and sinus cycle lengths of over 800 ms. Exercise testing by bicycle ergometry (4 patients) was normal in 1 case and revealed Mobitz II 2nd degree AV block in 3 cases. Baseline electrophysiological studies showed an A-H1 interval ranging from 60 to 100 ms (average 78 ms), a H1-H2 interval of 20 to 40 ms (average 31 ms) and a H2-V interval of 30 to 50 ms (average 32 ms). Block between H1 and H2 was observed: "spontaneously" during electrophysiological investigation in 6 cases, after IV atropine in 1 case, during overdrive atrial pacing at rates slower than 150/min in 7 cases, after atrial extrastimulus with a functional intra-His refractory period of over 420 ms in 7 cases, after ajmaline in 3 of the 4 cases in which this test was performed. A cardiac pacemaker was implanted in 10 patients in whom the initial symptoms have all regressed; the remaining patient considered to be "epileptic" had another syncopal attack under therapy and was finally paced. This series demonstrates that the diagnosis of median intra-His block depends on precise electrophysiological criteria and should be looked for even when the presenting symptoms are atypical; some of our patients complained only of tiredness. The value of Holter monitoring and careful endocavitary investigation is emphasised. Median intra-His block should be distinguished from longitudinal and functional His bundle dissociation.

Adolescent↗
PubMed1984

[Measured and estimated sinoatrial conduction during variations in rhythm. Microelectrode study of the isolated rabbit atrium].

Strips of isolated atrium were obtained from 10 rabbits to study the validity of indirect methods of estimating sinoatrial conduction time during variations of the sinus rhythm. Direct recordings of the trans-membrane action potential of the sinus node were made. Mapping of the sinus region was undertaken to determine the site of the dominant pacemaker. A quadripolar surface electrode was positioned on the lower part of the crista terminalis for stimulation and recording of the atrial potential. This enabled a comparison to be made between the indirect estimated and the directly measured conduction times. An intrasinusal shift of the dominant pacemaker was obtained by cooling from 38 degrees C to 35 degrees C. This shift occurs progressively in the cranino-candal direction. The estimated and measured conduction times were compared under basal conditions and after cooling. The sinus cycle was significantly longer (p less than 0.001) at 35 degrees C (318 +/- 68 ms) than at 38 degrees C (255 +/- 48 ms). The mean measured anterograde conduction time also decreased from 36 to 31 ms (p less than 0.01) and the mean measured retrograde conduction time also decreased from 39 to 33 ms (p less than 0.02); the total conduction time decreased from 75 to 64 ms (p less than 0.001). The results of the total estimated conduction times were discordant. The associated effects of stimulation and cooling can cause conduction defects and an overestimation of the conduction time.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1983

[Comparison of various indirect methods for evaluation of sinus function].

Sinus node function was evaluated by Mandel, Strauss and Narula's methods in 60 consecutive patients: 20 females, 40 males; average age 59 +/- 17 years. Three had second degree sinoatrial block, 2 had bradycardia-tachycardia syndromes and 10 had sinus bradycardia. The corrected sinus node recovery time was 414 +/- 417 ms. It exceeded 520 ms in 8 cases, 5 where the two other methods confirmed sinus node dysfunction, 1 where the two other methods showed no abnormality. In the last two patients pathological results with Narula's method coincided with normal values with Strauss' method but the basal sinus cycle and the post return cycle differed from one method to the other. The atriosinoatrial conduction time estimated by Narula's method was 274 +/- 117 ms. In the thirteen cases where it exceeded 300 ms abnormal results were also recorded with Strauss' (11 cases) and/or Mandel's method (7 cases). The atriosinoatrial conduction time assessed by Strauss' method was 239 +/- 106 ms. It exceeded 300 ms in 18 patients. In these patients the results of Narula and Mandel's methods were normal in 7 cases. This discordance cannot be explained either by variations in the catheter position, or by the duration of the basal sinus or the post return cycles. This raises the question of penetration of the sinus node by the last stimulus when Narula's technique is used. A significant linear correlation was observed between the atriosinoatrial conduction time assessed by Narula's method and the atriosinoatrial time assessed by Strauss' method (N = 60; r = 0,59) and with the corrected sinus node recovery time (N = 60; r = 0,43) and a double linear correlation was found with these two parameters (N = 60; r = 0,62). There was no significant linear correlation between the atriosinoatrial conduction time assessed by Strauss' method and the corrected sinus node recovery time (N = 60; r = 0,27). The atriosinoatrial conduction time evaluated by Narula's method seems to be intermediary between the two other parameters which seem to be independent of each other.

Adolescent↗
PubMed1983

[Conduction disorders and aneurysms of the sinus of Valsalva].

A series of 15 sinus of Valsalva aneurysms (SVA) admitted between 1961 and 1981 was reviewed to analyse associated conduction defects. It comprised 11 men and 4 women; the mean age was 31 years (range 16 to 53). The diagnosis of SVA was made at the time of rupture (4 cases), during investigation of associated cardiac disease (8 cases), at surgery (1 case) and during advanced conduction disorders (2 cases). All patients underwent catheterisation and angiography. Endocavitary electrophysiological studies were performed in 3 patients. Eight out of 15 patients had conduction defects which comprised: incomplete right bundle branch block (2 cases), atrioventricular block (AVB) (6 cases). Endocavitary investigation of 3 of the 6 AVB showed conduction defects at several levels: sino atrial, suprahisien, intrahisian and infrahisian blocks (1 case); transient complete AVB with 1 degree and 2 degree intrahisian block (1 case); complete AVB, six years after correction of SVA, due to infrahisian block (1 case). Thirteen of the 15 patients underwent surgery; none of the 9 cases of SVA without conduction defects before surgery developed conduction defects. Four of the 6 cases of AVB required permanent pacing; there was 1 postoperative death. One patient was not operated. These conduction defects were caused by the close relationship of the SVA to the intracardiac conduction pathways. The right anterior was the most commonly affected sinus. The investigation of AV conduction should be systematic in cases of SVA, and, conversely, the finding of AVB in young patients should alert the physician to the possibility of a SVA.

Adolescent↗
PubMed1983

[Supraventricular tachycardias induced by swallowing].

The authors report the case of a 34 year old woman admitted to hospital for attacks of atrial tachycardia inducing very poorly tolerated junctional tachycardia at 260 beats/min. The attacks were always induced by swallowing and could be reproduced at will. Electrophysiological studies could only be undertaken after the administration of large doses of amiodarone. An exclusively retrograde rapidly conducting paranodal accessory pathway was demonstrated with triggering of runs of reentrant tachycardia. No underlying gastro-oesophageal or cardiac disease apart from thromboembolism was found. Swallowing-induced supraventricular tachycardia is rare and possible mechanisms are discussed. The arrhythmia may be triggered by direct mechanical stimulation, by changes in vagosympathetic tone, or by an association of the two phenomena. Previously published reports describe similar clinical situations resulting from a variety of different mechanisms.

Adult↗
PubMed1982

Intra-SA-nodal pacemaker shift: indirect evaluation in the open chest dog.

Thirteen open chest dogs with normal sinus node function were studied by premature stimulations with a constant relative prematurity--50% of the preceding sinus cycle length. These premature beats were induced in the lower part of the crista terminalis of the right atrium and to the roof of the left atrium. Significant linear correlations were found between the return cycle (A2A3) and the spontaneous cycle (A1A1) lengths, with a slope of +0.75 in the right atrium, +1.36 in the left atrium. The evaluation of sinus node function is disturbed by pacemaker shifts, both spontaneous and induced. Sinus node organisation may be assessed by stimulating standardised sites, by measuring intra-atrial conduction time, and by comparing A2A3 with A1A1 at constant relative prematurity during significant variations in A1A1 obtained with changes in vago-sympathetic tone.

Animals↗
PubMed1981

[Contribution of the exercise test to the diagnosis of sinus dysfunction. Correlation with endocavitary explorations].

Standardised exercise electrocardiography was performed in 50 patients undergoing endocavitary electrophysiological investigation of sinus node function. There was no previous history of cardiac failure or coronary insufficiency, and the patients, who were not trained athletes, were investigated after interruption of any medication which could affect sinus node function. The endocavitary investigations comprised overdrive suppression with rapid atrial pacing (Mandel) premature extrastimulus method (Strauss) and stimulation at a relative constant prematurity of 50% (Normal values: A2 A3 - 2d - return cycle - sinoatrial conduction time - = 0,77 A1 A1 - spontaneous cycle - +345). A significant difference in the maximal heart rate on stress testing between normal subjects and patients with sinus node dysfunction was observed only when values obtained with the relative constant prematurity method was taken into consideration (24 cases) the relative constant prematurity method became more significant (p less than 0,001). This held true to a lesser degree for Mandel's method (p less than 0,02), but no significant difference was obtained with Strauss' method. The ratio of maximal heart rate to theoretical maximal heart rate for age gave similar results. The correlation between stress testing and the relative constant prematurity method is probably related to intra sinusal shift of the dominant pacemaker. Both investigations would seem to test the functional properties and the reserve of the sinus node, taking extrinsic factors such as vago sympathetic stimulation into account. Patients with functional sinus node dysfunction increase their heart rates normally on exercise (average maximum of 170 bpm); a maximal heart rate of less than 120 bpm is very suggestive of organic sinus node dysfunction.

Adolescent↗
PubMed1978

[The double ventricular response phenomenon in 2 cases of Wolff-Parkinson-White syndrome].

The authors report two cases of "true" consecutive double ventricular response caused by a single premature atrial stimulation; both were young men with Wolff-Parkinson-White syndrome. In both cases, the presence of a bundle of Kent was confirmed. The phenomenon of double ventricular response arising successively from the bundle of Kent and node-His pathway is rare, being mentioned in only two cases in the literature. It is only found when there is the combination of a good bundle of Kent, fair forward conduction, and a relative ventricle-His retrograde block. Amongst the other mechanisms for double ventricular repsonse, re-entry from branch to branch presents the most difficult differential diagnosis. From our observations, the forward characteristics of the spread through the bundle of His which always procedes the bundle of His which always precedes the second ventricular complex have been confirmed, especially in view of the freat variation in the position of this potential which can easily be explained by variations in intra-nodal conduction. In one of these cases, the atriogram, taken after the second ventriculogram, was provided by retrograde activity in the bundle of Kent.

Adolescent↗
PubMed1978

[Evaluation of sino-atrial function using the method of extrasystole induced by constant-relative premature impulses. 1. Method and normal results].

Atrial pacemaking under conditions of relative constancy (40 or 50% of the preceding cycle) enables us to calculate the immediate sino-atrial conduction time (retrograde and antegrade) (SACT). 17 patients were chosen for their normal sino-atrial function under spontaneous changes of the sinus cycle (SC). In each case, a significant inverse linear relationship was found between SACT and the corresponding SC. The mean correlation slope was -0.36 in 10 patients with no post-pacing depression (PPD). The slope was greater in 7 patients with a PPD (-0.89); if this depression is taken into account when the SACT is calculated, the slope decreases. In 5 patients, atropine (1 mg I.V. reduced the mean value of SC, and shortened (constant relative value) the SACT. The mechanisms for the spontaneous and induced variations in the sinus output are discussed; it may be that there are substitute pacemakers within the cells of the sino-artrial node, which are affected by variations in sympathetic or parasympathetic activity or by pacing. In clinical practice, automatism and conduction with the sinus node should be interpreted as inter-related functions, both under normal conditions and after vagal block.

Adult↗
PubMed1978

[Evaluation of sino-atrial function using the method of extrasystole induced by constant-relative premature impulses. 2. Application in 50 normal and abnormal studies].

The total immediate sino-atrial conduction time (SACT) as calculated by constant relative pacing, 40 or 50% of the immediate sinus cycle (SC), normally varies inversely with the SC. 50 patients were investigated by this method. In 38 patients without sino-atrial block (SAB) on the surface ECG, it was found that the mean slope of correlation between SACT and SC varied with the shape of the curve of Strauss and with the presence or absence of a post-pacing depression. The smallest slope was found in the group in which the curve of Strauss was horizontal in zone II, and in which there was no depression. In the groups with a rising zone II, comparative use of pacing with a fixed relationship in milliseconds suggested a phenomenon of decreasing retrograde conduction. In cases with sinus arrhythmia and a Strauss curve with scattered coordinates, the relationship between SACT and SC was maintained. 1st degree right-sided SAB should therefore be defined as a function of the immediate SC. In 12 other patients with SAB on the surface ECG, the immediate SACT was greatly lengthened so as to be immeasurable, and bore no relationship to the SC.

Adolescent↗
PubMed1969

[Not Available].

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