Effect of autonomic nervous system modulation on retrograde atrioventricular nodal conduction in the human heart.

Although the influence of the autonomic nervous system on anterograde atrioventricular nodal conduction is well established, its effect on retrograde atrioventricular nodal conduction has not been examined systematically. Since retrograde atrioventricular nodal conduction in subjects with normal anterograde conduction may vary from intact retrograde conduction to complete retrograde block when assessed during ventricular pacing, in this study patients with (a) intact retrograde atrioventricular nodal conduction (group 1) were studied during parasympathetic (vagal) stimulation by carotid sinus pressure and during sympathetic inhibition (propranolol 0.2 mg.kg-1 intravenously) and (b) retrograde atrioventricular nodal block (group 2) were studied during vagal blockade (atropine 0.04 mg.kg-1 intravenously) and during sympathetic stimulation (isoproterenol 1-4 micrograms.min-1 infusion). In both groups changes in sinus cycle length and anterograde atrioventricular nodal conduction were measured. In group 1 vagal stimulation by carotid sinus pressure in 20 patients caused the cycle length at which retrograde atrioventricular nodal block was induced to be significantly lengthened from a mean(SD) of 375(59) to 451(51) ms in six patients; caused complete retrograde block in 10 patients; and had no effect in four patients. Sympathetic inhibition by propranolol in another 15 patients delayed the onset of pacing induced retrograde atrioventricular nodal block from a mean(SD) of 340(60) to 418(80) ms in 11 patients; caused complete retrograde atrioventricular nodal block in three patients; and had no effect in one patient. In group 2 vagal blockade by atropine caused a 1:1 retrograde response during ventricular pacing up to a mean(SD) cycle length of 470(135) ms in six out of eight patients. The infusion of isoproterenol caused the retrograde atrioventricular nodal block to be abolished and 1:1 conduction to be resumed up to a ventricular pacing mean(SD) cycle length of 364(57) ms in six out of eight patients. It is concluded that (a) the autonomic nervous system modulates retrograde atrioventricular nodal conduction in a similar manner to its anterograde counterpart and (b) that since retrograde atrioventricular nodal conduction was reversible after the administration of either atropine or isoproterenol retrograde atrioventricular nodal block may be dynamic (physiological) rather than fixed (anatomical) in nature.

Bepridil for recurrent sustained ventricular tachycardias: assessment using electrophysiologic testing.

Bepridil was found to possess electrophysiologic properties common to class I and IV antiarrhythmic agents. Intravenous and oral bepridil were evaluated using serial electrophysiologic studies in a selected group of 9 patients with recurrent sustained ventricular tachycardia (VT) unresponsive to usual therapy, including amiodarone therapy in 15 patients. Intravenous bepridil treatment terminated sustained, well tolerated, pacing-induced VT in 3 of 6 patients and prevented the initiation of VT in 2 of these and in a patient in whom the drug failed to restore sinus rhythm. Oral bepridil was administered at a loading dose of 800 mg on day 1, and 500 to 600 mg the following days, and programmed electrical stimulation was repeated 2 to 6 days after initial study. Oral bepridil therapy prevented VT initiation in 6 patients (66%). The tachycardia cycle length was prolonged (30 to 105 ms) in 2 patients in whom VT remained inducible. In 1 patient the tachycardia cycle length significantly shortened after bepridil and prompt cardioversion was required. Five of the 6 patients with successful results underwent long-term oral treatment with bepridil. VT recurred in 1 patient during the hospitalization period and an adverse effect (paralytic ileus) in another patient required drug discontinuation. Three patients remain symptom-free over a follow-up of 4 to 13 months. These data suggest that bepridil may be useful in patients with recurrent, sustained VT.

Efficacy and safety of intravenous and oral diltiazem for Wolff-Parkinson-White syndrome.

The electrophysiologic effects and safety of diltiazem administered either intravenously or orally were studied in 14 patients with Wolff-Parkinson-White syndrome during orthodromic reentrant tachycardia and atrial fibrillation (AF). Anterograde and retrograde effective refractory periods of the accessory pathway did not change significantly from baseline during either i.v. or oral administration. Administration by either route prevented induction of sustained reentrant tachycardia in 8 patients. In 6 patients, the reentrant tachycardia was either nonsustained (2 patients) or sustained at much slower rates than the baseline rates (mean +/- standard deviation, baseline, 290 +/- 41 ms; i.v., 355 +/- 40 ms [p less than 0.001]; and oral, 377 +/- 33 ms [p less than 0.001]). In these patients anterograde atrioventricular conduction was prolonged significantly from the mean baseline value of 163 +/- 36 ms to 212 +/- 35 ms with i.v. administration (p less than 0.005) and 225 +/- 33 ms with oral administration (p less than 0.005). Retrograde conduction via the accessory pathway did not change significantly after administration of diltiazem. The shortest preexcited RR intervals during AF were significantly reduced during i.v. but not during oral administration: control, 327 +/- 47 ms; i.v., 270 +/- 28 ms (p less than 0.001); and oral, 323 +/- 44 ms (difference not significant). In 5 patients AF was sustained for a mean of 20 minutes after i.v. and for 12 minutes after oral administration (p less than 0.20), compared with a baseline mean value of 0.83 minute.(ABSTRACT TRUNCATED AT 250 WORDS)

Cochlear implantation in a pacemaker patient.

The authors present their experience with cochlear implantation in a 22-year-old patient who had a cardiac pacemaker because of complete atrioventricular block. The question of compatibility between the cochlear implant (multichannel Digisonic DX10AE) and the pacemaker (Biotronik Nanos-01AE) was raised. After consulting the two manufacturers regarding the risk of electrical interference, the authors decided to program the pacemaker in a locked mode (VOO) and then perform cochlear implantation. When the cochlear implant was switched on for the first time, electrocardiograms were obtained to ensure that the two devices were compatible. Absolutely no interference was detected. After a 3-year follow-up, cochlear implant performance remains excellent.

[Exercise test in isolated anomalies of auriculo-ventricular conduction in children and adolescents. Value in idiopathic auriculo-ventricular blocks and ventricular pre-excitation syndromes]. / L'épreuve d'effort dans les anomalies de la conduction auriculo-ventriculaire isolées chez l'enfant et l'adolescent. Valeur dans les blocs auriculo-ventriculaires idiopathiques et dans les syndromes de préexcitation ventriculaire.

Abnormal atrioventricular conduction in children and adolescents without obvious underlying cardiac disease poses the problem of long term prognosis. This study of 45 patients aged 8 to 18 years with congenital atrioventricular block (30 cases) or ventricular pre-excitation (15 cases), was undertaken to determine the value of exercise testing, a physiological adrenergic stress test, in the assessment of these patients. Our results show that exercise testing was valuable in determining the site of atrioventricular block: during exercise the degree of block increased in two patients, justifying electrophysiological investigations which showed infrahisian block in one case; when the block was stable or improved on exercise, the atropine test, performed in 21 cases, gave concordant results in 18 cases (the same change with atropine and exercise): the block was nodal in all these patients. A concordant response to exercise and atropine, improving the degree of block, indicates suprahisian block and endocavitary investigation would not seem to be necessary. On the other hand, when the degree of block increases or remains the same during exercise and/or the atropine test, the site of block cannot be predicted and endocavitary investigation and Holter monitoring may be required. In patients with ventricular pre-excitation, exercise testing provides information on the relative values of the effective refractory periods of the normal and accessory pathways: in the 10 cases in which endocavitary studies were undertaken, the exercise electrocardiogram changed in the expected manner (disappearance of the pre-excitation wave on exercise in patients with accessory pathways with longer refractory periods than the normal pathway and persistence of pre-excitation when the accessory pathway refractory period was shorter).(ABSTRACT TRUNCATED AT 250 WORDS)

[Criteria of localization of the bundle of Kent]. / Critères de localisation des faisceaux de Kent.

The high success rate (> 90%) of radiofrequency ablation of accessory pathways is related to accurate mapping. This determines the site of the accessory pathway and the best target for ablation with the object of reducing the number of applications and the associated morbidity. Analysis of the surface ECG is the first step of localisation of a Kent bundle. Different algorithms may be used based on the correlation between the polarity of the delta wave, of the QRS and the site of the accessory pathway confirmed at surgery or during radiofrequency ablation procedures. Some of the recent algorithms allow localisation of certain postero-septal or sub-epicardial pathways, the ablation of which can only be accomplished via the coronary sinus or one of its branches, or in an abnormally dilated coronary sinus, the so-called diverticulum. A relatively accurate localisation of the accessory pathway from the surface ECG reduces the duration of an ablation procedure and may economise the need for left-sided catheterisation. However, the endocavitary electrogrammes determine the precise target of ablation whether this be the ventricular or atrial pole of the bundle of Kent. The association of the criteria obtained by bipolar and unipolar recordings in sinus rhythm, during pacing or reentrant tachycardia enables accurate localisation in the majority of cases. Ablation of some pathways may be more complex because of their site or the presence of associated congenital or acquired cardiac disease which alters the anatomical or electrical markers. In these cases, the electrical criteria, especially those of the surface ECG may be erroneous and non invasive investigations such as Doppler echocardiography, isotopic ventriculography with phase analysis are most valuable with a positive predictive value of over 90%.

[Total or partial electrical interruption of the atrioventricular pathway. Evaluation of clinical results and indications]. / Interruption électrique totale ou partielle de la voie auriculo-ventriculaire. Appréciation des résultats cliniques et des indications.

After checking on the efficacy and innocuity of catheter ablation of the His bundle in an experimental study in the sheep, 22 patients with supraventricular tachycardia resistant to an average of 5.5 +/- 1.7 antiarrhythmic drugs per patient underwent this procedure. The most common arrhythmias were atrial fibrillation or flutter (poorly tolerated in 14 cases), and reciprocating tachycardia (8 cases, including 3 with accessory atrioventricular pathways). In 3 of the 5 patients with intranodal tachycardia, an initial attempt was made to modify one of the two AV nodal conduction pathways. Although complete atrioventricular block was obtained in all patients, atrioventricular conduction returned in 15 patients between the 30th minute and 4th day after the procedure. A second attempt at His bundle ablation was carried out in 9 patients. During follow-up ranging from 1 to 38 months, complete or an advanced degree of atrioventricular block persisted in 5 patients, the other patients being in sinus rhythm (12 cases) or slow atrial fibrillation (2 cases). The remaining patient who was in complete atrioventricular block died of septicaemia 2 months after the procedure. The clinical results were evaluated by electrophysiological investigation, exercise testing and Holter monitoring. There were 15 satisfactory clinical results (83.3 p. 100) and 3 poor results. This series shows that interruption or modification of the normal atrioventricular conduction pathway may be performed at low risk and with good results in a high percentage of cases. It is a valuable therapeutic option in patients with supraventricular tachycardia resistant to antiarrhythmic therapy.

[Treatment of recurrent ventricular tachycardia with hydroquinidine. Evaluation of its efficacy with electrophysiological technics]. / Traitement des tachycardies ventriculaires récidivantes par l'hydroquinidine. Appréciation de l'efficacité par les techniques électrophysiologiques.

Electrophysiological investigations were used to test the efficacy of dihydroquinidine chlorhydrate (600 or 1 200 mg/day) in a prospective study of 18 patients with recurrent ventricular tachycardia documented by electrocardiography. These patients did not respond to an average of 3.1 +/- antiarrhythmic drugs, including amiodarone in 12 patients. Hydroquinidine was well tolerated in 17 patients but had to be withdrawn in 1 patient because of hypotension. The effect of hydroquinidine on ventricular tachycardia induced by programmed pacing was evaluated after a 48 to 72 hours treatment, 3 to 5 hours after the last dose. After hydroquinidine it was not possible to induce ventricular tachycardia in 10 patients (58.8%). In the other 7 patients, it was possible to induce a ventricular tachycardia under treatment. In one case, hydroquinidine aggravated the arrhythmia as the induced tachycardia had a shorter cycle. In the other patients, hydroquinidine lengthened the tachycardia cycle by an average of 94 +/- 79 ms. The right ventricular refractory period increased cycle by 44 +/- 23 ms. Long-term hydroquinidine was prescribed for 7 patients, twice in association with amiodarone. Relapse was observed in 2 patients, 1 and 5 months after the onset of treatment. Five patients were well controlled by the treatment. The results of this study demonstrate the efficacy of hydroquinidine for the prevention of tachycardia induced by stimulation and underline its value in the treatment of sustained, recurrent ventricular tachycardia. This study illustrates the illustrates the importance of electrophysiological techniques for the identification of patients likely to benefit from a given antiarrhythmic treatment.

[Quantification of mitral regurgitation by cine-MRI. Comparison with transesophageal echocardiography in 45 patients]. / Quantification des régurgitations mitrales par ciné-IRM. Comparaision avec l'échographie doppler transoesophagienne chez 45 patients.

Cine-MRI demonstrates the presence of mitral regurgitation by a signal void. This study was undertaken to assess the value of this method for quantification of mitral regurgitation in a population not excluding either patients with mitral valve prostheses or those with atrial fibrillation. The subjects included had a mean age of 59 years and were referred for transoesophageal echocardiography, either for assessment of valvular heart disease (38 patients), or for detection of atrial thrombosis before external electrical cardioversion (7 patients). Eight patients had mitral valve prostheses and 19 were in atrial fibrillation. Cine-MRI was performed within 12 days of the transoesophageal echocardiography study with a 1.5 tesla magnet, using a sequence of gradient echo in 3 parallel planes in the 4 chamber view. The regurgitation was quantified by MRI from the extension of the signal void in the left atrium. The transoesophageal Doppler echocardiographic criteria were the width of the regurgitant jet at its origin, the intensity of the regurgitation signal recorded by continuous wave Doppler and the extension of the jet within the left atrium. The quantification by degrees 1 to 4 did not differ by more than 1 degree between the 2 techniques in 43 of the 45 patients. Out of 4 left atrial thrombus detected by transoesophageal echocardiography, only 1 was visible by MRI. The authors concluded that quantification of mitral regurgitation by cine-MRI provides similar results to those obtained by transoesophageal echocardiography and that the correlation remains valid in cases of atrial fibrillation. However, Doppler echocardiography provides further valuable information for the clinician.

[Supraventricular tachycardia induced by effort and by catecholamines]. / Tachycardie supraventriculaire induite par l'effort et les catécholamines.

The role played by catecholamines in the initiation of certain forms of ventricular tachycardia is now recognised. On the other hand, a similar predominant or exclusive mechanism has not been demonstrated in supraventricular tachycardia. We observed a rate case of reproducible attacks of junctional tachycardia on effort in a 45 year old man. This patient had experienced attacks of tachycardia on effort for a number of years, stopping about 10 minutes after the end of effort. An exercise stress test performed for an anginal attack, induced a narrow complex tachycardia at 270/min at the first minute of the recovery period which terminated spontaneously 18 minutes later after a brief episode of atrial fibrillation. During a second exercise stress test, an episode of tachycardia at 250/min was recorded at the second minute of recovery, lasting 11 minutes. Investigations showed a retrograde concealed septal bundle of Kent activated retrogradely during reciprocating tachycardia. A similar form of tachycardia was induced by an injection of isoproterenol. The adrenergic mechanism of the arrhythmia led to the prescription of a beta-blocker (propranolol 120 mg/day), which effectively prevented clinical tachycardia and the forms of tachycardia induced by ergometric tests 15 days and 3 months after the initiation of treatment.

[Sequential double demand programmable stimulation in the treatment of resistant supraventricular tachycardia. Long-term results]. / La stimulation séquentielle double-demande programmable dans le traitement des tachycardies supraventriculaires rebelles. Résultats à long terme.

Asynchronous pacing at a rhythm slower than that of the tachycardia (underdrive) is an established procedure for the reduction of supraventricular tachycardia. Simultaneous or sequential stimulation depolarising two parts of the circuit (atrium and ventricle) has a greater chance of reducing the tachycardia than stimulation of a single chamber. Five patients with supraventricular tachycardia resistant to antiarrhythmic therapy were treated by sequential pacing in the underdrive mode. Electrophysiological investigations showed a bundle of Kent to be responsible for the ECG appearances of Wolff-Parkinson-White (3 cases) with retrograde conduction only (concealed WPW) in 2 cases. One patient was able to put a stop to his attacks by the application of a magnet over the pulse generator. In four patients, a newly designed pulse generator, based on this concept, was implanted with the property of automatic detection of tachycardia (defined as a heart rate faster than 150/min) triggering almost simultaneous pacing of the coronary sinus and right ventricle (sequential interval of 65 ms) in the asynchronous mode at 77 bpm. The results were reviewed with a follow up of 6 to 36 months. This pulse generator was shown to be effective in both the reduction and prevention of episodes of supraventricular tachycardia. Sequential double demand pacing is a valuable and useful method of treating reentrant tachycardias associated with the WPW syndrome or concealed Kent bundles. It provides an alternative to surgery when the effective refractory period of the Kent bundle is long. Present advances in the field of cardiac pacing will probably result in a widening of the indications for this mode of therapy.

[Cardiomuscular lysosomal glycogenosis in adults without known enzyme deficiency. A cause of familial myocardiopathy and lysosomal glycogen overload with normal acid maltase]. / Glycogénose lysosomiale cardio-musculaire de l'adulte sans déficit enzymatique connu. Cause de myocardiopathie familiale et surcharge lysosomiale en glycogène avec maltase acide normale.

An unusual form of familial myocardiopathy is reported. The disease affected siblings entering adulthood and presented as subclinical skeletal muscle and patent cardiac muscle lesions. Quadriceps muscle biopsy performed in a young man who subsequently died of cardial failure revealed excessive lysosomal glycogen storage, as in type II glycogenosis, but biochemistry showed normal enzymatic activity. In a sister with hypertrophic myocardiopathy only leucocytes were examined; they also showed normal enzymatic activity. Other clinical manifestations of this form of familial myocardiopathy are hypoglycaemia and moderate skeletal muscle involvement. At histology, the image is that of Pompe's disease, but the acid maltase level is normal. The condition seems to be transmitted as an autosomal dominant trait.

[Andersen syndrome: a particular form of paralysis with cardiac dysrhythmia]. / Le syndrome d'Andersen: une forme particulière de paralysie périodique avec dysrythmie cardiaque.

Andersen syndrome includes a clinical triad with periodic paralysis, cardiac arrhythmia and dysmorphic features most often mild but relevant. It is a potassium channelopathy due to mutation of KCJN2 gene coding for Kir 2.1 protein. We report a familial case with mutation R218W of Kir 2.1 and discuss the main phenotypic and genetic aspects of Andersen syndrome. Muscle manifestations are essentially a periodic paralysis most often of hypokaliemic type. Muscle biopsy reveals tubular aggregates but can be normal as it is shown in the same patient in our kindred. Our proband complained of paralytic attacks since childhood and at adult age she demonstrated a mild permanent deficit of pelvic girdle muscles as it has been described in other types of periodic paralysis after a long duration course. Cardiac manifestations may include in a variable manner a long QT syndrome, premature ventricular contractions, complex ventricular ectopy, polymorphic or bidirectional ventricular tachycardia. Imipramine had a positive effect on arrhythmia in our case. Dysmorphic features are often mild and have to be cautiously looked for as a clue to the diagnosis of Andersen syndrome. They can be easily overlooked if not systematically looked for. Clinical expressivity is variable including in the same family. In our observation, the daughter showed a complete triad, early expressed, which allowed the diagnosis. Her father was late diagnosed on ventricular dysrhytmia but without muscle manifestations and dysmorphic features. Since KCJN2 gene mutation identification, locus heterogeneity of Andersen syndrome was shown. Andersen syndrome kindreds without mutations in KCNJ2 were clinically indistinguishable from KCNJ2-associated subjects. KCNJ2 gene encodes the inward rectifier K+ channel Kir2.1 which plays an important role in maintaining membrane potential and during the terminal phase of cardiac action potential repolarization. Several studies showed a dominant negative effect of the mutation on Kir 2.1 channel function.

[New developments of antiplatelet drugs]. / Nouveaux développements des médicaments antiplaquettaires.

A better knowledge of platelet activation mechanisms has made it possible to develop antiplatelet agents that are capable of inhibiting primary haemostasis at very precise levels. Many of these agents block the synthesis or receptor of an hemostasis I agonist. Thus, the thromboxane A2 receptor can be blocked, or its synthesis can be interrupted, by thromboxane synthetase inhibitors, by cyclooxygenase inhibitors, or by omega 3 fatty acids which are competitive inhibitors. Inhibitors of thrombin (hirudin), PAF acether and serotonin (ketanserin) also are available. Other antiplatelet agents secreted by endothelial cells act as haemostasis I antagonists by elevating platelet cAMP or cGMP levels (prostacyclins and analogues, nitrate derivatives). Monoclonal antibodies and RGD peptides directly inhibit the glycoproteins that are responsible for platelet adhesion or aggregation, but their users are faced with problems of cost and route of administration. Of all these new antiplatelet agents, only ticlopidine, which has an imperfectly known mode of action, has proved effective in multiple situations, but its use is limited by its side-effects.

[Prognostic value of thallium-201 myocardial scintigraphy in patients with hypertension, suspected of coronary disease]. / Valeur pronostique de la scintigraphie myocardique au thallium 201 chez l'hypertendu suspect de maladie coronaire.

This study was undertaken to determine the prognostic value of exercise myocardial scintigraphy in hypertension patients suspected of coronary disease. One hundred and thirty six hypertension patients (mean age: 59) suspected of coronary disease were monitored for 46 months after thallium 201 exercise myocardial scintigraphy (tomographic mode). Prognostic factors analysed were clinical (typical nature of pain, exercise blood pressure), electrocardiographic (presence of repolarisation abnormalities in resting ECG), ergometric (electrically positive test) and scintigraphic (existence or not of transitory hypofixation). Events sought were: death of coronary origin, non-fatal myocardial infarction, aorto-coronary bypass and coronary angioplasty. One-way analysis showed that the existence of transitory hypofixation by scintigraphy, positive exercise electrocardiogram and typical angina pain enabled the prediction of coronary events. Thus 14 of 36 patients (39%) with transitory or combined hypofixation had a coronary event as against 7 of the 100 patients without transitory hypofixation. Only the existence of transitory hypofixation retained a prognostic value for coronary events by multivariate analysis (relative risk = 5.4, p = 0.001). It was also found that the prognosis was good when scintigraphy did not reveal transitory hypofixation while exercise testing was positive (2 coronary events/27 patients). It is concluded that, despite the possibility of "false positives", linked in particular to myocardial hypertrophy, myocardial scintigraphy offers better prediction of coronary events in hypertension patients that other clinical or electrocardiographic parameters.