Cryoablation of junctional tachycardia at high risk of atrio-ventricular block.

INTRODUCTION: Transcatheter cryoablation is an alternative option for the treatment of supraventricular tachycardia, due to its very low risk of permanent atrio-ventricular block. However, the overcost of cryocatheter and the high recurrence rate of this emerging technology braked its large use. This study reports the results of an approach using cryoablation for the treatment of junctional tachycardia (JT) in selected patients at high risk of atrio-ventricular (AV) block. PATIENTS AND METHODS: Out of a series of 199 patients with JT treated by catheter ablation, 26 benefited from cryoablation (mean age 32.8+/-15 years, 15 males). The indications were the presence of an accessory pathway with a high risk of atrio-ventricular block (n=7), a slow pathway difficult to ablate, with a risk of atrio-ventricular block (n=7), a recurrence after a RF procedure, during which a transient atrio-ventricular block has occurred (n=4), and finally patients at young age (n=8). RESULTS: The primary success rate was 92%. No permanent AV block has been reported, neither with RF nor with cryoablation. The recurrence rate at 9+/-10 months was at 29% after cryoablation and 8.6% after RF. In case of AV nodal reentrant tachycardia, the additional cost of cryotherapy catheter has been avoided in 76.85% of cases. The use of a cryotherapy catheter and RF catheter has been necessary for the remaining cases. CONCLUSION: This study demonstrates that an approach, reserving cryoablation in selected patients at high risk of AV block is an alternative strategy to "the systematic use" of cryotherapy in the ablation of JT with a high efficacy, an excellent safety and a reduced cost.

[Prevention of recurrent amiodarone-induced hyperthyroidism by iodine-131]. / Prévention des récidives d'hyperthyroïdie a l'amiodarone par l'iode131.

Amioradone-induced hyperthyroidism is a common complication of amiodarone therapy. Although definitive interruption of amiodarone is recommended because of the risks of aggravation of the arrhythmias, some patients may require the reintroduction of amiodarone several months after normalisation of thyroid function. The authors undertook a retrospective study of the effects of preventive treatment of recurrences of amiodarone-induced hyperthyroidism with I131. The indication of amiodarone therapy was recurrent, symptomatic, paroxysmal atrial fibrillation in 13 cases and ventricular tachycardia in 5 cases (M = 14, average age 64 +/- 13 years). The underlying cardiac disease was dilated cardiomyopathy (N = 5), ischaemic heart disease (N = 3), hypertensive heart disease (N = 2), arrhythmogenic right ventricular dysplasia (N = 2) or valvular heart disease (N = 2). Two patients had idiopathic atrial fibrillation. An average dose of 576 +/- 184 MBq of I131 was administered 34 +/- 37 months after an episode of amiodarone-induced hyperthyroidism. Amiodarone was reintroduced in 16 of the 18 patients after a treatment-free period of 98 +/- 262 days. Transient post-radioiodine hyperthyroidism was observed in 3 cases (17%). Sixteen patients (89%) developed hypothyroidism requiring replacement therapy with L-thyroxine. There were no recurrences of amiodarone-induced hyperthyroidism. After 24 +/- 17 months follow-up, the arrhythmias were controlled in 13 of the 16 patients (81%) who underwent the whole treatment sequence. The authors conclude that preventive treatment with I131 is an effective alternative to prevent recurrence of amiodarone-induced hyperthyroidism in patients requiring reintroduction of amiodarone to control their arrhythmias.

[Tachycardia-induced cardiomyopathy in children: a difficult diagnosis but a reversible form of left ventricular dysfunction]. / Myocardiopathie rythmique de l'enfant : un diagnostic difficile mais une forme curable de dysfonction ventriculaire gauche.

UNLABELLED: Tachycardia-induced cardiomyopathy is a reversible left ventricular dysfunction caused by cardiac arrhythmia. Because of its reversibility, a correct diagnosis and treatment are necessary. The aim of our study was to precise the diagnostic procedures of the tachycardia-induced cardiomyopathy and to study the left ventricular function after the correction of the arrhythmia. PATIENTS AND METHODS: A retrospective study done between 1992 and 2001. Children studied were followed-up for: an idiopathic form of cardiomyopathy, in which the etiological research showed a cardiac arrhythmia; a cardiac arrhythmia associated to a cardiomyopathy. An electrocardiogram recorded the cardiac arrhythmia. The left ventricular function was evaluated by an echocardiography before and every month after the correction of the cardiac arrhythmia. RESULTS: Twelve children were included, ages ranged from 2 months to 15 years (median 11 years). Four patients presented a cardiac insufficiency associated to arrhythmia; three followed-up for an arrhythmia developed a cardiomyopathy; five whose cardiac arrhythmia was not easy to demonstrate had an idiopathic form of cardiomyopathy. The Wilcoxon test showed a significant amelioration (P < 0.01) of the left ventricular function after the correction of the cardiac arrhythmia. CONCLUSIONS: Tachycardia-induced cardiomyopathy in children is curable and the diagnosis is quite difficult. Pediatricians and family doctors should try to look for specific signs of cardiac insufficiency or arrhythmia. Pediatric cardiologists should search a tachycardia-induced cardiomyopathy in every idiopathic form of cardiomyopathy.

[Ectopic atrial tachycardia complicating a congenital left atrial aneurysm: value of an electro-anatomical mapping system]. / Tachycardie atriale ectopique compliquant un anévrysme congénital de l'auricule gauche: apport d'un système de cartographie électro-anatomique.

The authors report the case of a patient with a congenital left atrial aneurysm complicated by ectopic atrial tachycardia treated successfully by surgery. Transoesophageal echocardiography and magnetic resonance imaging provided accurate measurements of the aneurysm and its anatomical relationships. Three-dimensional electro-anatomical mapping with the CARTO, system (Biosense) confirmed the shape and dimensions of the aneurysm. The system showed the electrically mute zones and the ectopic focus situated just beyond the aneurysmal neck. Surgical ablation confirmed the morphological and functional data of the imaging techniques and the patient was definitely cured.

[Dissection of the aorta complicated by aorto-pulmonary fistula]. / Dissection aortique compliquée de fistule aorto-pulmonaire.

The authors report the case of chronic dissection of the aorta presenting with congestive cardiac failure. The diagnosis was made for the first time by transoesophageal echocardiography which showed both the dissection of the aorta and its fistulalisation into the pulmonary artery. Aortography confirmed the diagnosis. The patient underwent surgery which consisted of suture of the fistula and replacement of the ascending aorta with a prosthetic tube. The outcome was favourable after 8 months follow-up.

Autonomic influences on ventricular repolarization in congestive heart failure.

We studied the QT interval rate-dependence in patients with congestive heart failure (CHF). The long-term autonomic nervous function was investigated by separate analysis of diurnal and nocturnal periods. For this purpose, QTm rate-dependence was determined from Holter recordings. Twelve patients with stable CHF (mean age 63 +/- 2 years) and 15 healthy subjects (mean age 59 +/- 4 years) were included in the study. CHF patients showed an increased nocturnal QTm rate-dependence when compared to normal subjects (0.150 [95% confidence interval (CI) 0.114 to 0.186] versus 0.106 [95% CI 0.080 to 0.133], P < .05). In contrast, QTm rate-dependence was not significantly different between the 2 groups during the day (0.177 [95% CI 0.149 to 0.210] in the CHF group versus 0.194 [95% CI 0.158 to 0.231] in the control group). It was also not significantly different between day and night for the CHF group, thus showing a loss of the circadian modulation in these patients. Thus, ventricular myocardial properties are altered by changes in the autonomic nervous system in CHF, as observed at the atrial level. These modifications may be related to the increased susceptibility to ventricular arrhythmias.

Coronary-to-bronchial artery communication: report of two patients successfully treated by embolization.

We report two cases of coronary-to-bronchial artery communication responsible for coronary steal. In both cases the anastomosis originated from the proximal circumflex artery and developed because of bronchiectasis. In both cases closure of the anastomosis was achieved successfully by embolization. To date, the patients remained free from symptoms.

[Drug therapy of ventricular tachycardia]. / Traitement médicamenteux des tachycardies ventriculaires.

Despite the introduction of new therapeutic techniques such as radiofrequency ablation and the implantable defibrillator, the classical opposition of monomorphic ventricular tachycardia in apparently normal hearts and that arising from documented cardiac disease remains useful. In the first case, treatment is only symptomatic whereas, in the second, lethal progression to sudden death must be prevented. Generally speaking, in chronic post-infarct situations, betablockers are underused although they have been shown beyond doubt to reduce cardiovascular mortality. This is probably explained by the fear of possible haemodynamic decompensation in patients who often have left ventricular dysfunction. Nevertheless, different randomised studies of the use of betablockers in cardiac failure have reported reduced mortality with no serious side effects. The use of beta-blockers is therefore advisable, and possible inpatients with or without sustained ventricular tachycardia and underlying cardiac disease. In cases at high risk of sudden death, amiodarone may be associated. Recent randomised studies (MADIT, AVID), comparing the use of implantable defibrillators with those of antiarrhythmic therapy, have shown better results with the implantable defibrillator. However, in these studies, only about 10% of patients received betablockers in the antiarrhythmic treatment groups. This factor has introduced some doubt as to the real benefit of implantable defibrillators. Therefore, a randomised study comparing the efficacy of betablockers with amiodarone against implantable defibrillators is desirable in order to determine the respective indications of each of these two therapeutic modalities.

Familial incidence of late ventricular potentials and electrocardiographic abnormalities in arrhythmogenic right ventricular dysplasia.

Familial forms of arrhythmogenic right ventricular dysplasia (ARVD) have been described. Signal-averaged electrocardiograms (SAECGs) and standard electrocardiograms have been used to detect ARVD. The purpose of this prospective study, for a given family member, was to evaluate the risk of having ARVD or only belonging to an affected family. To address these issues, we assessed the incidence of late ventricular potentials and electrocardiographic (ECG) abnormalities in the families of our patients with ARVD. SAECGs and electrocardiograms were recorded in 101 eligible family members and compared with those recorded in ARVD patients with sustained ventricular tachycardia (13 patients in 12 families), and in 37 control subjects with a normal electrocardiogram. The incidence of late ventricular potentials was significantly higher in family members than in control subjects (16% vs 3%, p <0.05). The incidence of ECG abnormalities was 34% in family members. When the incidence of late ventricular potentials and/or ECG abnormalities were added up, results were 38% abnormal findings in family members. Late ventricular potentials and/or ECG abnormalities were found in members of all 7 families; these abnormalities were initially thought to be sporadic forms, and thereafter were classified as familial forms. Thus, SAECGs and standard ECG recordings in ARVD family members showed 38% abnormal findings, and that all cases of ARVD could be classified as familial forms. The incidence of familial forms of ARVD was greater than was previously believed, which is highly suggestive of a genetic transmission of the disease in our geographic area.

[Ablation of the slow pathway in reciprocating nodal rhythms by radiofrequency]. / Ablation de la voie lente des rythmes réciproques nodaux par application d'un courant de radiofréquence.

Radiofrequency ablation is a therapeutic alternative to drug therapy in recurrent reciprocating nodal rhythms. Selective ablation of the slow pathway guided by endocavitary recordings has the advantage of being effective at the price of a very low incidence of atrioventricular block. The authors report their experience with this technique. Fifty consecutive patients with recurrent attacks which were syncopal or uncontrolled by medical therapy, underwent selective ablation of the slow pathway. Firstly, they all underwent electrophysiological investigation to confirm the nodal origin of the reciprocating rhythm before proceeding to ablation itself, guided by the search for the slow pathway potentials. After ablation, it was impossible to trigger reciprocating tachycardia. Interruption of the anterograde slow pathway was achieved in 24 patients and of the retrograde pathway in 1 patient : the other 25 patients went on having dual conduction but with a prolongation of the effective refractory period of the slow pathway (268 +/- 46 ms vs 251 +/- 41 ms : p < 0.01). There were no cases of permanent complete atrioventricular block. Interruption of the slow pathway was associated with shortening of the effective refractory period of the rapid pathway (323 +/- 71 ms vs 348 +/- 80 ms : p < 0.01), which was not observed in cases of persistent dual conduction. No recurrence of tachycardia was observed during follow-up (mean period = 19.2 months) : however, control endocavitary studies in 25 asymptomatic patients after 1 to 3 months showed recurrence in 4 cases, which led to immediate further radiofrequency ablation which was successful. The authors conclude that guided selective radiofrequency of the slow intranodal pathway is a remarkably effective and reliable method of treating poorly tolerated or resistant reciprocating nodal tachycardias. Widening of the clinical indications to patients not wishing to undergo long-term antiarrhythmic therapy is now possible.

[Echo-Doppler and stenosis of the renal arteries. Report of 86 cases]. / Echo-Doppler et sténose des artères rénales. Etude a propos de 86 patients.

Duplex-scan is widely used for arterial stenosis diagnosis. Its role in detection of renal artery stenosis remains controversial (2, 17, 19, 28). The aim of this study was to determine retrospectively if duplex-scan is accurate for diagnosis of renal artery stenosis. During 36 months, 764 patients had a renal artery examination with duplex-scan: 90 patients had also renal arteriography. Duplex-scan was feasible in 95% of cases (excess bowel gas or major obesity gave to duplex-scan incomplete results in four patients upon 90). Ninety-three per cent of patients had hypertension; 20% had renal failure; 61% had obstruction of coronary, carotid artery or lower limb arteries. Nineteen patients among 86 had also an intravenous renal arteriography. We compared duplex-scan with venous angiography and intra-arterial arteriography. Duplex-scan criteria for stenoses were: a maximal systolic velocity (MSV) above 180 cm/s for detection of 60% to 79% stenoses and a MSV superior to 300 cm/s for detection of 80% to 99% stenoses. Global results showed a good sensitivity 59/64 (92%) and specificity 112/117 (96%) for duplex-scan. Duplex-scan is accurate for diagnosis of renal artery stenosis in a selected population.

[Hemangioma of the interventricular septum simulating right obstructive cardiomyopathy. Apropos of a case and review of the literature]. / Hémangiome du septum interventriculaire simulant une cardiomyopathie obstructive droite. A propos d'un cas et revue de la littérature.

The authors report a case of haemangioma of the interventricular septum, a rare cardiac tumour (2.8% of all primary cardiac tumours) simulating right obstructive cardiomyopathy. Based on a review of the literature, they emphasize the diversity of the clinical expression of this disease and the uncertain medium and long-term outcome of operated and nonoperated tumours.

[Comparative study of the efficacy and tolerability of 2 modalities of intravenous cibenzoline administration in the reduction of recent spontaneous atrial arrhythmia]. / Etude comparative de l'efficacité et de la tolérance de deux modalités d'administration de la cibenzoline intraveineuse dans la réduction des arythmies auriculaires spontanées et récentes.

This multicentre, single blind, parallel group study compared the efficacy and clinical and electrocardiographic tolerance of a 2 minute intravenous administration of cibenzoline at a dose of 1.2 mg.kg-1 with that of a 10 minute 1.75 mg.kg-1 infusion in patients presenting with spontaneous atrial fibrillation (AF) for less than 6 weeks. Sixty-two patients (40 men and 22 women) with an average age of 62 years and presenting with sustained AF for at least 30 minutes with a ventricular rate greater than or equal to 80 bpm were randomly assigned to groups and received via the intravenous route either one of the two treatments. Efficacy (return to sinus rhythm) was assessed by an ECG recording every 5 minutes and at 45 and 60 minutes thereafter. Sixty-one of the 62 randomised patients were assessed for efficacy. Cibenzoline, administered in the form of a bolus or infusion, proved effective within one hour in 4 patients in each group (13%) and arrhythmia persisted with ventricular rate of less than 80 bpm in 10 (33%) and 5 (16%) of the patients respectively. In patients in whom sinus rhythm was not restored, ventricular rate was significantly reduced by cibenzoline. The patients in whom normal rhythm was restored under one of these treatment regimens were significantly younger. Patients in whom rhythm returned to normal following the administration of the bolus had AF of significantly more recent onset than that of the patients in whom abnormal rhythm persisted, whilst the history of the AF did not differ significantly between these two types of response after the infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

[Right accessory pathways with slow and decremential anterograde conduction. Electrophysiological changes during ablation of the proximal atrial poles]. / Les voies accessoires droites à conduction antérograde lente et décrémentielle. Observations électrophysiologiques lors de leur ablation centrée sur l'insertion proximale atriale.

Right sided accessory pathways with slow and decremential anterograde conduction differ from the anatomical substrates of the nodo-ventricular connections described by Mahaim. The connection may also be atrio-ventricular or atrio-fascicular. The authors report a series of 6 patients (2 men, average age 31 +/- 9 years) with antidromic reciprocating tachycardia implicating accessory pathways with decremential conduction (wide QRS complexes with left bundle branch block) the radiofrequency ablation of which was centered on the proximal atrial pole. The increment of pre-excitation was 75 +/- 18 ms. No nodo-ventricular or nodo-fascicular connections were observed. One patient had an atrio-ventricular connection, the mapping and ablation (5 applications) of which were performed on the annulus, as if it were a bundle of Kent. Five patients had a nodo-fascicular connection which was masked during sinus rhythm. The localisation of the proximal atrial insertion on the tricuspid annulus was initially estimated by studying the superior junction of the circuit and by endocavitary stimulation, and then by recording the M potential (activation of the accessory pathway). This was recorded in 4 patients, either at a specific point on the annulus (lateral or postero-lateral) which was the target of ablation (3 patients, 5 +/- 3 applications) or over a wider region (2 cm) at which ablation failed (1 patient: 13 applications). The site of the increment was determined in 2 patients and was proximal to the M potential. The M potential could not be recorded on the annulus in one patient. In 2 patients, the M potential was also recorded along the side of the pathway on the antero-lateral wall of the right ventricle of the tricuspid valve at its distal pole. In 2 patients, ablation was centered on the distal pole in second intention, near to the terminal part of the right bundle where it was localised in one of the two (18 applications). Finally, ablation was obtained in 5 out of 6 patients. They remain asymptomatic after 12 +/- 7 months follow-up. These cases show that accessory pathways with slow decremential conduction usually behave like a complete conduction pathway with an accessory laterally situated atrioventricular node on the tricuspid, an accessory bundle and a distal insertion which are all accessible to ablation.

[Determination of the optimal atrioventricular timing by impedance plethysmography in patients with cardiac pacing; correlations with left ventricular filling]. / Détermination du délai auriculo-ventriculaire optimal par pléthysmographie d'impédance chez des patients stimulés; corrélations avec le flux de remplissage ventriculaire gauche.

The stroke volume (SV) was measured by the change in the impedance in thirteen patients with dual chamber pacemakers at different atrioventricular delay (AVD) intervals: 31 to 219 ms or 75 to 220 ms. The mitral inflow was also recorded by Doppler echocardiography at each AVD with measurement of the duration of mitral flow (MFD) and the velocity time integral (VTI). All thirteen patients were studied in the DDD mode; in addition, 5 patients were studied in the atrial sensing ventricular stimulation VDD mode. The SV measurement by impedance plethysmography was reproducible with an average variability of 3.5%: the optimal AVD was determined by this method in 11 patients with DDD and 4 patients with VDD pacing: in 3 patients (2 in DDD and 1 in VDD mode) 2 optimal AVD were obtained. The optimal AVD was 123 +/- 31 ms (63 to 156 ms) in DDD mode and 91 +/- 17 ms (63 to 110 ms) in VDD mode. The analysis of left ventricular filling showed that changes in AVD led to similar changes in mitral VTI. The MFD increased as the AVD was shortened to a constant value at the optimal AVD. In all patients, the optimal AVD was obtained when the MFD became maximal and constant. Measurement of MFD is a simple and rapid means of assessing optimal AVD at rest in patients with dual chamber pacing systems.

[Infectious endocarditis on permanent endocavitary pacemakers: value of echocardiography and review of the literature]. / Endocardites infectieuses sur sondes de stimulation endocavitaire permanentes: intérêt de l'échocardiographie et revue de la littérature.

Infectious endocarditis around indwelling pacemakers is rare (0.15% of all implantations). They have a gloomy prognosis with a global mortality rate of nearly 34% as emerges from this review of the literature concerning 58 cases of infectious endocarditis published within the past 16 years. On the basis of the 6 cases which the authors report, they stress the importance and sometimes difficulty of using ultrasound in a positive diagnosis. Cardiographic ultrasound, which can determine the size and emboligenic nature of vegetations is capital in choosing how to remove the pacemakers. Percutaneous ablation by simply pulling or by catheterization currently gives the best results, but it may be necessary to resort to surgery involving right atriotomy if emboligenic vegetations are present. By combining antibiotic treatment and ablation of the intracavitary material, a cure is obtained in 92% of cases. These figures should be compared with the lack of success of using antibiotic treatment alone which results in a high level of mortality (84%).

Microgravity and orthostatic intolerance: carotid hemodynamics and peripheral responses.

A ground-based model [24 h of bed rest (BR) with head-down tilt (HDT)] was used to investigate the cardiovascular deconditioning responsible for orthostatic intolerance, frequently observed after weightlessness flights. This experimental deconditioning is shown to be distinguished by an increase of mean blood pressure (P < 0.05), with increased total peripheral resistances (TPRs). Systolic tangential tension of the carotid arterial wall, cardiac output and frequency (spectral analysis), and plasma norepinephrine and epinephrine were not significantly altered, while plasma dopamine was increased (P < 0.05). Cardiovascular homeostasis was challenged before and after 24 h of BR with HDT through -40 mmHg lower body negative pressure (LBNP). Systolic tangential tension of the carotid wall was decreased, with a decrease of systolic pressure and cardiac output; increased heart rate was likely due to an increase of sympathetic drive with a decrease of vagal braking. The overall picture was not changed after 24 h of BR with HDT, except for a lack of increase of TPRs: their increase (+13.7%, P < 0.05) before was no longer observed after (-2.6%) 24 h of BR with HDT. This apparent deficiency cannot be explained. However, a heterogeneity in the response of TPR should be considered because the magnitude of the increase of blood pressure to cold pressor test was the same after 24 h of BR with HDT as it was before.(ABSTRACT TRUNCATED AT 250 WORDS)