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M Fromer

Publications and source records attributed to M Fromer.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Efficacy of adenosine triphosphate in terminating supraventricular tachycardia].

The efficacy of adenosine triphosphate (ATP) was tested in 23 patients suffering from supraventricular tachycardia; 10 patients had orthodromic circus movement tachycardia and 13 typical av nodal reentrant tachycardia. At a mean dose of 0.18 mg/kg all tachycardias were halted in less than 1 minute due to transient acute av nodal block followed by return to normal av conduction within 8 seconds. All patients had transient minor side effects. One elderly subject had a short episode of atrial fibrillation after the acute av block. In conclusion, ATP is useful and safe for rapid termination of supraventricular tachycardias incorporating the av node in their circuit.

Adenosine Triphosphate↗
PubMed1993

[Interventional arrhythmology].

Interventional arrhythmology deals with the nonpharmacological management of patients with symptomatic arrhythmias. Percutaneous catheter ablation is used to cure patients with arrhythmias due to accessory pathways or AV-node reentrant tachycardia. In patients with drug-refractory sustained, hemodynamically significant ventricular tachyarrhythmias, implantable third generation defibrillators provide an effective therapeutic modality. Our article provides a brief overview of these new therapeutic modalities and summarizes our local experience.

Arrhythmias, Cardiac↗
PubMed1993

Acute and long-term ventricular stimulation thresholds with a new, iridium oxide-coated electrode.

Efforts have been made to design electrodes that significantly reduce not only the acute and chronic stimulation thresholds, but also attenuate the early peaking phenomenon and polarization. At two voltage levels (2.7 V and 5.4 V, respectively), we evaluated the right ventricular stimulation thresholds obtained with a new, iridium oxide-coated electrode in ten patients who received a VVI pacemaker. Measurements were made at implant and at multiple intervals for 1 year. Pulse width stimulation thresholds at implant were as follow: 0.04 +/- 0.008 msec at 2.7 V, 0.03 +/- 0.004 msec at 5.4 V; values at 2 weeks were 0.14 +/- 0.06 msec at 2.7 V, 0.07 +/- 0.025 msec at 5.4 V; values at 3 months were 0.09 +/- 0.03 msec at 2.7 V, 0.05 +/- 0.01 msec at 5.4 V; values at 1 year were 0.08 +/- 0.02 msec at 2.7 V, 0.04 +/- 0.01 msec at 5.4 V. The maximal increase of 0.11 +/- 0.05 msec occurred at 2.7 V, 2 weeks after implant. Our results indicate that this new electrode provides low acute and long-term stimulation thresholds, as well as an attenuated early peaking phenomenon, being able to stimulate safely at 2.7 V even early after implant.

Aged↗
PubMed1993

[Initial experience of percutaneous catheter ablation using radiofrequency of atrioventricular accessory pathways].

This paper reports the authors' preliminary experience in catheter ablation by radiofrequency current of 46 accessory atrioventricular pathways in 45 symptomatic patients with supraventricular tachyarrhythmias resistant to medical therapy. With an average follow-up period of 5.5 +/- 4 months the global success rate was 80%, ranging from 96% in left lateral to 33% in antero septal accessory pathways. It increased from 65% in the first 20 patients to 88% in the last 25 patients. The average duration of radioscopy was significantly shorter in left lateral pathways than in other localisations (p < 0.02); it was also shorter when ablation was successful. Complications were observed in 4 patients (9%) and included one complete atrioventricular block and 3 femoral arterial lesions. Anaesthetic assistance was required in 14 cases (31%), either at the patient's request or to allow reduction of atrial fibrillation. Percutaneous catheter ablation of accessory atrioventricular pathways with radiofrequency current is effective and gives good results; very strict selection of initial patients and the respect of certain conditions taking into account the experience of the medical team, the technically difficult approach of certain accessory pathways and the risks of ablation of pathways running near the atrioventricular node or His bundle, are necessary for successful results when learning this technique.

Adolescent↗
PubMed1992

[Endocavitary ablation: a new therapeutic approach to supraventricular tachycardia].

Nowadays patients suffering from supraventricular tachycardia are first treated with antiarrhythmic drugs. In refractory cases alternative treatment is antitachycardia pacemaker implantation or surgery. Recently new percutaneous catheter techniques have been developed to ablate directly the anatomical substrate responsible for the arrhythmia by delivering energy (high or low energy shock or radiofrequency) at the tip of a catheter. This article summarizes the results of clinical application of these different techniques and briefly presents our experience. The very recent studies with RF in patients with drug-refractory av nodal reentry or accessory pathway related tachycardia (WPW syndrome) report a success rate of 92-99% with a very low complication rate. If the long term success of radiofrequency is confirmed this technique will emerge in the near future as the treatment of choice in patients suffering from symptomatic supraventricular tachycardia, since it avoids expensive, longlasting drug treatment with the permanent risk of side effects.

Atrial Fibrillation↗
PubMed1992

[Circadian variability of rhythm disorders].

Cardiac arrhythmias exhibit also a circadian variability. It is impressingly apparent in sustained ventricular tachycardia and sudden cardiac death. Adrenergic stimulation during morning hours, a physiologic event for the transition from nocturnal to diurnal activity, appears to be an important arrhythmogenic factor (25). The results of the BHAT-study show that beta blocking agents may substantially reduce the risk for sudden cardiac death during morning hours. This notion should thus be considered in treating patients at risk.

Arrhythmias, Cardiac↗
PubMed1992

Ultrarapid subthreshold stimulation for termination of atrioventricular node reentrant tachycardia.

OBJECTIVES: We investigated the efficacy and safety of ultrarapid subthreshold electrical stimuli in terminating sustained atrioventricular (AV) node reentrant tachycardia. BACKGROUND: Subthreshold stimuli, singly and in trains, have been reported to prolong the effective refractory period, inhibit the response to subsequent suprathreshold extrastimuli and to terminate ventricular tachycardia and reciprocating tachycardia. METHODS: Seventeen consecutive patients with inducible sustained slow-fast AV node reentrant tachycardia (mean tachycardia cycle length 358 +/- 61 ms) were studied. Trains of subthreshold stimuli were tested at various right atrial sites. RESULTS: Trains of subthreshold stimuli reproducibly terminated AV node reentrant tachycardia in 15 patients without administration of adjunctive pharmacologic agents. Effective subthreshold current strength ranged from 0.5 to 1.5 mA (mean 0.9 +/- 0.3). The cycle length of effective subthreshold stimuli trains ranged from 30 to 80 ms (mean 57 +/- 17), and the number of stimuli in the train ranged from 4 to 16 (mean 8 +/- 4). The site of successful termination was the proximal coronary sinus in 6 patients and the right low atrial septum in 12. During successful subthreshold termination, no atrial capture could be detected. Neither atrial fibrillation nor flutter nor tachycardia acceleration occurred. CONCLUSIONS: Low current, high frequency trains of stimuli, when applied at a site presumed to be close to the reentrant circuit, provided a safe and effective method of terminating the common type of AV node reentrant tachycardia. This technique could be used to identify critical parts of the reentrant circuit suitable for ablation and further investigations with this method are warranted.

Adult↗
PubMed1992

Subthreshold electrical stimulation for termination and prevention of reentrant tachycardias.

Subthreshold electrical stimulation (STS) was used to terminate and prevent reentrant supraventricular and ventricular (VT) tachycardia. Of 12 patients with SVT, 8 had atrioventricular nodal (AVN) reentry, and 4 had orthodromic tachycardias. Trains of STS applied close to the AVN area terminated the tachycardias in five of the eight patients with AVN re-entry and two of the patients with orthodromic tachycardia. In 13 patients with recurrent sustained hemodynamically stable VT (mean cycle length 370 +/- 40 ms), trains of STS were delivered at the site of early activity during the tachycardia. Number of train cycles ranged between 3 to 8 pulses and their cycle lengths ranged between 20 and 70 ms. In 7 of the 13 patients VTs were effectively terminated by STS application close to the site of early activity and in the remaining 6 patients it did not. In nine patients the effect of STS applied at the site of early activity on VT induction from the right ventricular apex was examined. In four of the nine patients STS prevented VT induction and in the remaining five patients it did not. These observations suggest that STS applied in proximity to the area critical for initiation and maintenance of reentry can terminate or prevent induction of the tachycardia.

Adult↗
PubMed1992

Efficacy of automatic multimodal device therapy for ventricular tachyarrhythmias as delivered by a new implantable pacing cardioverter-defibrillator. Results of a European multicenter study of 102 implants.

BACKGROUND: Third-generation implantable cardioverter-defibrillators are devices designed to treat ventricular tachycardia (VT) and ventricular fibrillation (VF) by means of overdrive pacing, cardioversion, or defibrillation. So far, the efficacy of tiered therapy has been documented only in small series. Therefore, a European multicenter clinical evaluation study of a new tachyarrhythmia control device, the Medtronic PCD pacer-cardioverter-defibrillator with epicardial patch-lead configuration, was undertaken. METHODS AND RESULTS: We report on 102 patients (mean age, 55 +/- 13 years) from 11 European centers. PCD devices implanted between May 1989 and February 1991 were included. The patients suffered from hemodynamically significant ventricular tachyarrhythmias not suppressed by antiarrhythmic drug therapy and unrelated to acute myocardial infarction; one patient had nonsustained VT and severely depressed left ventricular function. Seventy patients had coronary artery disease with old myocardial infarctions, 23 had cardiomyopathies of various etiologies, and nine patients had no detectable heart disease. Mean ejection fraction was 36 +/- 14% (range, 10-76%). Mean intraoperative defibrillation threshold (51 patients) was 10.6 +/- 5.1 J (range, 2-18 J). The documented follow-up ranged from 1 to 21 months (mean, 9.4 +/- 5.8 months), or 79.9 cumulative patient-years. Perioperative mortality was 3.9%. The actuarial survival rate at 12 months was 91%. One sudden arrhythmic death occurred. Sixty patients (58%) received device therapy. Seventeen patients had therapies only for "VF" episodes, 16 patients only for VT, and 28 patients for VT and "VF" episodes. Based on device memory data, 1,235 spontaneous VT episodes were detected and treated in 43 patients. Twelve hundred four of these VT episodes received painless initial antitachycardia pacing therapy, restoring sinus rhythm in 91%. The 108 ongoing episodes received 209 multiple therapeutic attempts. Eighty-five additional overdrive pacing therapies restored sinus rhythm in 30%. Initial ineffective antitachycardia pacing therapies received 51 cardioversion pulses. The success rate was 61%. Seventy-three additional cardioversion pulses were delivered to backup ineffective pacing therapy as well as ineffective secondary cardioversion pulses. Their success rate was only 40%. Two hundred eighty-six spontaneous episodes were detected in 44 patients as "VF." Overall defibrillation efficacy was 97.6%. CONCLUSIONS: The implanted device nearly eliminates sudden arrhythmic death in patients with documented, potentially fatal ventricular tachyarrhythmias. Automatic tiered therapy is highly effective to restore sinus rhythm, provided that an integrated two-zone tachycardia detection algorithm is used, assigning lower tachycardia rates to overdrive pacing and/or cardioversion and higher tachycardia rates to defibrillation. In general, spontaneous VTs can be terminated by automatic overdrive pacing, and painful or disturbing countershock therapies are not required to terminate the majority of spontaneous VT episodes.

Death, Sudden, Cardiac↗
PubMed1992

[Sudden cardiac death: possibilities of interventional therapy].

There is, at present, no method to prevent sudden cardiac death. However, in patients with documented high risk the implantable automatic cardioverter defibrillator is the only reliable alternative. However, the electrical discharges of high energy may cause discomfort and pain. Antitachycardia pacing is effective for most episodes of ventricular tachycardia and can effectively reduce the number of electrical shocks to be delivered.

Death, Sudden, Cardiac↗
PubMed1992

Transcatheter ablation of cardiac tissue: advantages and disadvantages of different ablative techniques.

Transcatheter ablation techniques are emerging as an alternative therapeutical tool in the management of cardiac arrhythmias. Catheter ablation was initially introduced as the last resort to ablate the atrioventricular nodal conduction in patients with atrial fibrillation and uncontrolled ventricular response and in patients with drug refractory ventricular tachycardias. Direct current energy was used as the sole source of energy, but because of potential significant complications and early and late mortality, presumably mostly due to ventricular tachyarrhythmias, other sources of energy were sought. Radiofrequency current which does not produce barotrauma and does not require general anesthesia rapidly replaced direct current ablation in many centers. Early results with radiofrequency current ablation of the atrioventricular node and accessory atrioventricular pathways are very encouraging. The results of radiofrequency as well as direct current ablation for atrial flutter, atrial tachycardia and ventricular tachycardia, where the components of reentry circuit are less defined, are not as favorable as those of AV junctional tachycardias. However, improvement of catheter and generatory technology and better understanding of the mechanisms of ventricular tachycardias and characteristics of the target site will enhance the results of catheter ablation in ventricular tachcardias. The procedures are still considered investigational, and mostly done by very experienced groups at tertiary referral hospitals with surgical teams available in case of serious complications. Larger patient populations and longer follow-up periods are required before these techniques expand to community hospitals and to patients with minimal symptoms or asymptomatic individuals as a prophylaxis therapy.

Cardiac Catheterization↗
PubMed1991

Experience with a new implantable pacer-, cardioverter-defibrillator for the therapy of recurrent sustained ventricular tachyarrhythmias: a step toward a universal ventricular tachyarrhythmia control device.

Ten consecutive patients (mean age 57.9 +/- 7.6 years) were treated with an investigational tachyarrhythmia control device, the implantable Medtronic Pacer-, Cardioverter-, Defibrillator model 7216A or 7217B. All patients had coronary artery disease with old myocardial infarctions and presented hemodynamically significant sustained ventricular tachyarrhythmias not suppressed by antiarrhythmic drug therapy and unrelated to acute myocardial infarction. In two patients a nonthoracotomy lead system was implanted. Lowest effective defibrillation energy ranged from 5 to 18 joules (mean 12.2 +/- 4 joules) for the epicardial bielectrode systems and were 15 and 18 joules for the nonthoracotomy lead system implants. The postoperative periods were unremarkable. Follow-up ranged from 7 to 19 months (mean 13.8 +/- 4.5 months). Spontaneous tachyarrhythmia episodes were detected and treated by the device in six patients, five of them received staged therapies. No deaths occurred and no hospital admissions were necessary for device related or ventricular tachyarrhythmia related complications. In conclusion, this integrated device represents a major step toward the development of a universal ventricular arrhythmia control device.

Aged↗
PubMed1991

Antiarrhythmic treatment of atrioventricular tachycardias.

Atrioventricular (AV) tachycardia includes both AV nodal reentrant tachycardia (AVNRT) and AV reentrant tachycardia (AVRT) using an accessory pathway. The treatment of the acute attack is different from the long-term treatment of both AVNRT and AVRT. Verapamil and adenosine, by prolonging the refractory period of the AV node, are highly effective in terminating acute attacks of AVNRT and orthodromic AVRT. Conversion to sinus rhythm is achieved in approximately 90% of the episodes of tachycardias with both agents given intravenously. The initial dose of verapamil is 0.075-0.1 mg/kg and a subsequent bolus of 5 mg can be given to a maximal dose of 15-20 mg. The initial dose of adenosine is 3 or 6 mg, but doses of 9 or 12 mg can be administered if smaller dosages have been unsuccessful. Other agents producing lengthening of the refractory period of the accessory pathway in AVRT or of the fast pathway in AVNRT often terminate reentry tachycardia. Such agents are class IC antiarrhythmic drugs such as flecainide or propafenone and class IA drugs such as procainamide. In patients with accessory pathways and antidromic tachycardia or atrial fibrillation conducting via an accessory pathway, treatment with verapamil or digoxin should be avoided because these agents may enhance the conduction properties of the accessory pathway, thereby leading to an increase of the ventricular rate or even to ventricular fibrillation. Prevention of AVNRT episodes can be obtained with various antiarrhythmic drugs. Digoxin alone or in combination with beta-blockers is effective in approximately 50% of the cases and especially when the combination proved to be successful during electrophysiological testing.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Sustained ventricular tachycardia: inducibility during invasive electrophysiologic studies].

Electrophysiologic studies are used for diagnosis and treatment in patients with sustained ventricular tachycardia. This method can only be employed if high inducibility of the spontaneous tachycardia can be demonstrated. We therefore investigated prospectively the induction yield in 35 patients with a history of documented sustained ventricular tachycardia. The patients' mean age was 58 years. Coronary artery disease was present in 24 patients, cardiomyopathy in 4, other organic heart diseases in 4, and no heart disease in 3. The ventricular tachycardia induction protocol consisted of three extrastimuli delivered during sinus rhythm and at two pacing cycle lengths, followed by intravenous isoproterenol if no tachycardia was induced before. With the method sustained ventricular tachycardia was induced in 100% of patients with coronary artery disease and cardiomyopathy, in 75% of patients with other heart diseases and in 33% of patients without detectable heart disease. We conclude that electrophysiologic studies have a high yield of sustained ventricular tachycardia induction in patients with underlying organic heart disease. The rational basis for use of electropharmacologic testing therefore exists in these patients. However, in patients without heart disease, the low sensitivity of electrophysiologic studies precludes its use for drug efficacy testing.

Adult↗
PubMed1990

Clinical efficacy of radiofrequency current in the treatment of patients with atrioventricular node reentrant tachycardia.

Eight women (mean age 41 years, range 24 to 62) with drug-resistant atrioventricular (AV) node reentrant tachycardia underwent radiofrequency catheter ablation. Radiofrequency energy was delivered in a unipolar mode with use of a back paddle as the anode placed between the two scapulae. The total applied energy was 2,233 +/- 1,919 J. The AH interval increased from 87 +/- 13 to 113 +/- 17 ms (p less than 0.05) and the PQ interval increased from 141 +/- 15 to 169 +/- 34 ms (p less than 0.05). The anterograde Wenckebach cycle length increased from 300 +/- 41 to 320 +/- 42 ms (p less than 0.05). Retrograde conduction was abolished in five patients. Atrioventricular node tachycardia was still inducible in three patients. During a follow-up period of 9 +/- 3 months, four patients remained clinically asymptomatic without drug therapy and four patients had recurrent symptoms. Three of the latter responded to previously unsuccessful antiarrhythmic drugs and the fourth patient underwent surgical cure for persistence of tachycardia. Right bundle branch block occurred in five patients; it was permanent in four and transient in one. In conclusion, radiofrequency catheter ablation represents a valuable but still investigational therapy in patients with drug-refractory AV node reentrant tachycardia.

Adult↗
PubMed1990

Is there an isolated arrhythmogenic right atrial myocarditis?

Two cases with drug refractory ectopic atrial tachycardia are described. A map-guided partial resection of the right atrium (RA) was done after preoperative endocardial catheter mapping had shown well-defined areas of fractionated RA potentials. Intraoperatively, there were no aneurysmal formations present as described by other authors. Histopathologic examination of the resected tissue showed atrial myocarditis in both patients. Postoperative right ventricular myocardial biopsies revealed no inflammatory tissue. A minor elevation of antibodies against echoviruses was found in one case. Postoperative electrophysiologic studies were negative. We conclude: focal RA myocarditis without concomitant ventricular myocarditis may represent one cause of drug-resistant ectopic atrial tachycardia. Map-guided surgical intervention may cure the disease.

Adult↗