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Biomedical subjects

G Kirkorian

Publications and source records attributed to G Kirkorian.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Ablation of accessory pathways by radiofrequency current. Towards a simplified approach of Wolff-Parkinson-White syndrome?].

From December 1990 to April 1992, 41 consecutive patients (22 men and 19 women with an average age of 35 +/- 16 years -6-72) underwent ablation of accessory atrioventricular conduction pathways (Bundles of Kent) for poorly tolerated and/or medically resistant supraventricular tachycardias. In 33 cases, the arrhythmia was a paroxysmal SVT, in 7 cases atrial fibrillation, and in 1 patient incessant junctional tachycardia causing left ventricular dysfunction. The Wolff-Parkinson-White syndrome was apparent in 30 patients and concealed in 11 cases. The location of the Kent bundle was left lateral in 22 cases (53.7%), posterior paraseptal in 9 cases (21.9%), right lateral in 5 cases (12.2%) and anterior paraseptal in 5 cases (12.2%). The Kent bundles were ablated by radiofrequency currents in 38 cases (92.7%); in 2 patients (4.9%) in whom radiofrequency could not be used (increased impedance) high energy electrical shock was successful. In one patient (2.4%), it was not possible to suppress the Kent bundle. A single session of radiofrequency ablation was sufficient in 33 cases: 7 cases (17.5%) required 2 (4) or 3 (3) sessions. The average number of sites of application per patient was 8.8 +/- 8.8. The duration and intensity were respectively 32.2 +/- 9.3 (5-60) seconds and 25 +/- 15 (20-30) watts. With an average follow-up of tachycardia or of ventricular preexcitation have been observed in the 40 patients. In addition, in 36 patients, electrophysiological control studies confirmed the initial result with absence of any disturbance of nodohisian conduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

[New approach to implantation of automatic defibrillators using video-thoracoscopy].

Nonthoracotomy lead systems are increasingly used in patients (pts) with implantable cardioverter defibrillator (ICD). In this setting, due to high energy requirements, a subcutaneous patch may be necessary in addition to endocardial leads. However in some patients, high defibrillation threshold (DT) may persist leading to thoracotomy for epicardial patch placement. In a preliminary experience, 3 patients with high DT (> 20J) following endocardial lead system, underwent the insertion of a extrapericardial patch under video-thoracoscopic control. A left subcostal incision extended to the left pleural cavity was performed. Using thoracoscopy the patch was positioned on the pericardium, sutured and connected to the defibrillator. DTs were 10, 10 and 20 J respectively in our 3 patients. Postoperative course was uneventful. Thoracoscopy allows other techniques such as a stellectomy, which we performed in a 33 year old woman with long QT syndrome. Patients were reassessed after 8 days and 2 months. Termination of induced ventricular fibrillation was achieved with the same minimal energy levels used peroperatively. In conclusion, extrapericardial patch insertion using thoracoscopy may help reduce DT in ICD patients with a non thoracotomy lead system. Comparison with other lead configurations requires further investigation.

Adult↗
PubMed1993

[Prognosis and long-term development of arrhythmogenic dysplasia of the right ventricle].

The authors studied the clinical, angiographic and electrophysiological features, and the long-term outcome of patients with arrhythmogenic right ventricular dysplasia (ARVD). The study was retrospective and involved 22 patients (3 women and 19 men) with an average age of 36 years at the time of their first documented ventricular tachycardia (VT) and admitted to hospital between 1971 and 1989. The diagnosis of ARVD was based on the association of monomorphic VT with a left bundle branch block morphology and right ventricular abnormalities on angiography. Fifteen patients were treated by antiarrhythmic drugs alone, 5 by antiarrhythmic drugs and tachycardia ablation and 2 by antiarrhythmic drugs and cardiac transplantation. An automatic defibrillator was implanted in one patient. After the first episode of VT, the beginning of follow-up, the criteria of evaluation were mortality, right heart failure and the evolution of the arrhythmia. The study population had the following characteristics. Familial forms or ARVD were observed in 18%. The mitral ventricular arrhythmia was often induced by exercises (45%). Twenty-one patients had a sustained VT and 1 patient had non-sustained VT. The resting ECG in sinus rhythm was abnormal in all cases. Thirty-two different VT morphologies were recorded. The abnormalities of the right ventricular wall motion on ventriculography were localised in 45% of cases and diffuse in 55% of cases. Seventy per cent of patients undergoing electrophysiological investigation had inducible sustained VT. The clinical outcome after an average of 10.7 years' follow-up was: 17 survivors, 3 sudden deaths and 4 cases of right ventricular failure. The 10 year actuarial survival rate was 75%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Prolonged QT, atrioventricular block, and sudden death in the newborn: an electrophysiologic evaluation.

An electrophysiologic study was performed in the first month of life in a patient with the congenital long QT syndrome and spontaneous episodes of 2/1 atrioventricular block. The block could be reproduced by incremental atrial pacing, and its infrahisian location was associated with a prolongation of the refractoriness in the ventricular muscle itself. Surprisingly, intravenous propranolol aggravated this phenomenon by further prolonging the QT interval. Sudden death occurred shortly thereafter during Holter monitoring and was due to a sudden resumption of normal AV conduction after an episode of 2:1 block, immediately followed by ventricular fibrillation.

Cardiac Pacing, Artificial↗
PubMed1991

[Diagnosis of the mechanism of reciprocating tachycardia by a simplified electrophysiological study].

The authors attempted to identify the parameters which best differentiated intranodal reentry from tachycardias associated with an accessory pathway during a simplified electrophysiological study. The data were obtained by using two catheters, one recording right atrial activity and the other delivering programmed stimulation in the right ventricle. Sixty-four patients in whom the mechanism of their tachycardias had previously been determined were studied. There were 19 intranodal and 45 accessory pathway tachycardias. The following parameters were studied: the ventriculo-atrial interval during tachycardia; the prematurity of atrial activity in response to programmed ventricular stimulation; the shortest ventriculo-atrial interval when the atrial activity was premature; the difference between the shortest ventriculo-atrial interval with atrial prematurity and the ventriculo-atrial interval during tachycardia; in the absence of prematurity the ventriculo-atrial interval with the shortest ventricular coupling was used. The ventriculo-atrial interval during tachycardia was shorter in intranodal reentry (43 ms vs 170 ms, p less than 0.001). This interval was greater than 120 ms only in accessory pathway tachycardias and was only under 75 ms in patients with intranodal tachycardias. Premature atrial activation was observed in 42% of intranodal and 98% of accessory pathway tachycardias (p less than 0.001). The predictive value for tachycardias involving an accessory pathway was 85% when the auriculogramme was premature and, conversely, it was 92% for intranodal tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Catheter ablation of the atrial myocardium in human type I atrial flutter.

To avoid atrioventricular node-His bundle ablation, catheter ablation of the atrial myocardium was attempted in eight patients with drug refractory type I atrial flutter. In seven of eight patients, a zone of prolongation and fragmentation of the endocardial electrogram was found in the low posterior part of the right atrium. Entrainment of the atrial flutter by high right atrial pacing was accompanied by local recording of second-degree regional block in several atrial sectors but never in the low septal area. We, therefore, hypothesized that the latter represented the critical slow conduction zone of the reentrant flutter circuit. One or two cathodal DC shocks were locally delivered without immediate or late complications. One single ablation attempt was performed in five patients, whereas three patients underwent a second attempt because of early flutter recurrence. Patients were initially discharged without (and after a second session with) antiarrhythmic drugs. After a mean follow-up of 15.5 months (range, 10-23 months), five patients are free of arrhythmias without antiarrhythmic drug therapy. Two patients did not experience atrial arrhythmias while on a drug regimen that was previously found to be ineffective, and a third patient had flutter recurrences. This study suggests that patients with type I atrial flutter referred for atrioventricular node-His bundle ablation may be successfully managed by delivering the ablative shock directly on the atrial arrhythmia substrate.

Adult↗
PubMed1989

Electrophysiologic basis of catheter ablation in atrial flutter.

A reentrant mechanism is believed to be responsible for atrial flutter. The recent development of the entrainment criteria further supports this theory, and there is a general consensus that circus movement is the underlying abnormality that supports this arrhythmia. In most clinical studies, abnormal fragmented (or double spike) electrograms, suggesting the presence of areas of localized slowing of conduction or block, have been reported. They are almost always recorded in the lower and posterior portion of the right interatrial septum, but also frequently in the high lateral portion of the right atrium. The determination of their involvement in the reentry pathway is important for designing curative procedures such as surgery or ablation. The low atrial septal area surrounding the mouth of the coronary sinus was suspected as being the critical area of slow conduction in atrial flutter. Rapid pacing at that site can yield a surface electrocardiographic pattern similar to the clinically occurring arrhythmias. Additionally, the flutter circuit can be accelerated during atrial pacing at fixed and slightly faster rates than the intrinsic tachycardia rate--the so-called entrainment phenomenon. When entrainment criteria are fulfilled, tachycardia termination being by definition ruled out, any concomitant recorded local type II block identifies an area that must be outside the circuit. Such local block may be recorded either spontaneously or during entrainment and therefore helps in identifying atrial slow conduction areas that do not belong to the reentrant path. This approach was applied to identify the optimal ablation site in 8 patients with long-standing drug resistant atrial flutter. In 7 of 8 patients, we were able to identify a fragmented potential in the low posteroseptal area during sustained atrial flutter.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Flutter↗
PubMed1988

Electrophysiologic effects of propranolol in intraventricular conduction disturbance.

Sixteen patients underwent electrophysiologic studies before and after intravenous infusion of propranolol, 0.1 mg/kg. All of them had intraventricular conduction disturbances. A significant (p less than 0.01) increase occurred after propranolol in the mean spontaneous cycle length (mean change 122 ms) and the AH interval (mean 28 ms). The HV interval did not change significantly. The effective refractory period of the His-Purkinje system increased in 4 of 5 patients (mean net change 44 ms, p greater than 0.10). In 7 patients with phase 3 infranodal block, the longest cycle length for producing block increased after propranolol in 5 and remained unchanged in 2 (mean increase 40 ms, p less than 0.02). Two patients showed phase 4 atrioventricular block. Propranolol increased the critical cycle length by an average of 120 ms. Propranolol-induced bradycardia restored stable atrioventricular conduction in 2 patients with intermittent 2:1 block but facilitated the occurrence of high grade infranodal block in 1 patient. Thus, propranolol can impair His-Purkinje conduction in patients with preexisting infranodal abnormalities.

Aged↗
PubMed1988

[Comparison of etomidate and thiopental for the anesthesia in cardioversion].

A controlled study was carried out, comparing etomidate and thiopentone used for anaesthesia for cardioversion. Eighty patients presenting with supraventricular tachyarrhythmias were randomly allocated to two groups with stratification for duration of supraventricular tachyarrhythmias and cardiothoracic ratio. After premedication with 10 mg of diazepam, anaesthesia was induced and maintained if necessary with etomidate (0.3 and 0.15 mg.kg-1 respectively) or thiopentone (3 and 1.5 mg.kg-1 respectively). The following observations were made by an independent observer: energy of the electric discharge, systolic and diastolic arterial pressures, heart rate, apnoea with duration, quality of anaesthesia, side-effects if present, and induction, anaesthesia and recovery times. A drawing test and an ambulation test were carried out after recovery. Data were analysed using one-way analysis of variance (continuous variables) and chi-squared test with Yates correction for small numbers (categorical variables) with p less than 0.05 considered significant. The thiopentone (THIO) and etomidate (ETO) groups were similar, except for premedication and number of NYHA class III and IV patients, being more common in ETO (p = 0.04; p = 0.05). Anaesthesia time was 4.6 +/- 2.3 min in THIO and 9.9 +/- 3.5 min in ETO (p less than 10(-9)) with more reinjections in THIO (p = 0.003). Awakening time was shorter in THIO (p less than 10(-6)) and graphic test was carried out better at 15 min in THIO. No difference was found later for graphic test and ambulation. Apnoea was more frequent in THIO (p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

A comparative evaluation of the effects of propafenone and lidocaine on early ventricular arrhythmias after acute myocardial infarction.

A double-blind, placebo-controlled trial comparing the antiarrhythmic effects of lidocaine (given intravenously as a bolus injection of 100 mg followed by an infusion of 2 mg min-1) and propafenone (given as a bolus of 105 mg followed by 300 mg orally every 8 h) was conducted in the first 24 h following acute myocardial infarction. Analysis of ventricular arrhythmias was carried out by Holter recordings. The three treatment groups, propafenone (36 patients), lidocaine (28 patients), and placebo (25 patients), did not differ with respect to age, gender, prevalence of previous infarction, delay from the onset of pain to hospitalization, clinical features on entry (the patients with heart failure or malignant arrhythmias were excluded), site of acute myocardial infarction, or CPK peak. A decrease in the number of ventricular premature beats was noted with lidocaine, but was not statistically significant. The analysis of the first 8 h showed trends suggesting that only lidocaine could suppress complex arrhythmias, couplets and ventricular tachycardia. The drugs were well tolerated. Mean plasma concentrations of propafenone and lidocaine were 517 +/- 464 ng ml-1 and 3.84 +/- 1.10 mg l-1, respectively. In conclusion, this study does not favour the use of propafenone as an alternative to lidocaine therapy during the acute phase of myocardial infarction.

Anti-Arrhythmia Agents↗
PubMed1988

[Anticoagulants in the treatment of severe pulmonary embolism. A prospective study].

This prospective study was designed to obtain information on the fate of patients with severe pulmonary embolism who received anticoagulants as first-line treatment, in order to identify those in whom other treatments available might be expected to reduce mortality or sequelae. Thirty-seven patients selected as they showed evidence of acute cor pulmonale entered the study. Seven of them (18.9 p. 100) died in hospital, and these were patients whose age (p = 0.004), degree of pulmonary obstruction (p = 0.008) and serum lactate dehydrogenase level (p = 0.001) were significantly higher than those of the other patients. The mean values of these parameters (64 years, 72 p. 100 and 450 IU/l respectively) made it possible to select patients with a high risk of death. At the end of the follow-up period (25 +/- 12 months) only 2 patients complained of moderate dyspnoea, in contrast with the high incidence (17/18 patients) of paraclinical abnormalities observed 3 months after the initial accident. We conclude that clinical trials comparing other treatments with the one we used would be useful if their objective was to reduce mortality in high risk patients. On the other hand, it seems impossible to demonstrate a functional improvement: we found our treatment satisfactory and its results independent of the abnormalities observed on the 3rd month.

Adolescent↗
PubMed1987

Effects of intravenous sotalol in patients with atrioventricular accessory pathways.

Effects of intravenous injection of 0.6 mg/kg sotalol, a beta-blocking agent with additional class III properties, were studied by means of electrophysiologic techniques in 14 patients, seven with the Wolff-Parkinson-White syndrome and seven with concealed atrioventricular (AV) accessory pathways. Sotalol brought about a significant increase in the retrograde effective refractory period of the anomalous pathway, whereas changes in the antegrade effective refractory period were more variable. In five of nine patients with electrically induced reciprocating tachycardia sotalol prevented the initiation of sustained reentry. In most cases the suppression of the circus movement was the result of the development of AV nodal block. Thus our data support the use of sotalol for the treatment of tachycardias incorporating anomalous AV conduction pathways.

Adolescent↗
PubMed1987

Electrophysiological action of bepridil on atrioventricular accessory pathways.

The electrophysiologic properties of bepridil, a calcium channel blocker with additional effects on fast response tissues, were investigated in 10 patients with atrioventricular accessory pathways. Seven patients had Wolff-Parkinson-White syndrome, and three had concealed atrioventricular pre-excitation. A dose of 4 mg/kg was administered intravenously over five minutes. Bepridil increased the AH interval and the functional refractory period of the atrioventricular node. The effective refractory periods of the right atrium and right ventricle were also increased. Bepridil prolonged refractoriness in the accessory pathway both in the anterograde and retrograde direction. After bepridil administration it was impossible to induce reciprocating tachycardia electrically in two patients because of conduction block in the normal pathway. On the other hand, the zone of tachycardia was often increased after bepridil. Nevertheless, the heart rate during tachycardia was slowed by depression of conduction in both the normal and accessory pathways. The findings of this study provide a basis for the antiarrhythmic action of bepridil in patients with atrioventricular accessory pathways.

Adolescent↗
PubMed1986

Electrophysiologic effects of cibenzoline in humans related to dose and plasma concentration.

The electrophysiologic effects of a new antiarrhythmic agent, cibenzoline, were investigated in 25 patients with an average age of 62 years. The compound was administered intravenously, as a bolus given over 2 minutes, then as a slow infusion over 40 minutes. Each subject was randomly allocated to receive one of the following four doses: 1.55 mg/kg (six patients), 1.8 mg/kg (six patients), 2.2 mg/kg (six patients), or 2.6 mg/kg (seven patients). Plasma cibenzoline concentrations at these doses were 378 +/- 80,525 +/- 194, 618 +/- 72, and 731 +/- 196 ng/ml, respectively. Administration of 1.55 mg/kg cibenzoline significantly shortened the sinus cycle (60 msec on average; p less than 0.025) and increased intraatrial (+8 msec; p less than 0.05) and His-Purkinje conduction times (HV interval + 13 msec; p less than 0.001). At 1.80 mg/kg, prolongation occurred in the HV interval (+9 msec; p less than 0.02), the duration of the QRS complex (+20 msec; p greater than 0.05), and the QT interval (+18 msec; p less than 0.025). At the higher doses these changes became more marked (maximum increase: HV = +16 msec, p less than 0.001; QRS + 25 msec; p less than 0.001; QT + 26 msec, p less than 0.05), and additional effects on atrioventricular nodal conduction time (AH interval + 17 msec; p less than 0.05) and atrial (+20 msec; p less than 0.05) and ventricular (+10 msec; p greater than 0.05) effective refractory periods were observed. Prolongation of the QRS duration was the effect that correlated best with plasma cibenzoline levels (r = 0.47; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Bundle branch reentrant tachycardia treated by electrical ablation of the right bundle branch.

A 66 year old man presented with multiple episodes of tachycardia. Some had QRS complexes with a right bundle branch block configuration identical to those of sinus beats. The onset of the tachycardia was preceded by premature His bundle depolarizations. There was a His potential before each QRS complex of the tachycardia. Atrial activity was dissociated. Occasionally the appearance of sinus beats with a left bundle branch block pattern announced a tachycardia with an identical configuration and atrioventricular dissociation. His bundle activity occurred before the QRS complex and was followed by a right bundle branch deflection. A reentrant mechanism within the bundle branch system was invoked. One 200 J shock was delivered through an electrode catheter to the site of the right bundle branch. The postprocedure course was uneventful (follow-up 10 months).

Aged↗
PubMed1984

Premature atrial stimulation during regular atrial pacing: a new approach to the study of the sinus node.

Using an induced premature atrial depolarization after atrial pacing for 8 beats to scan the postpacing cycle, sinus node (SN) response was studied in 23 patients and the results were compared with those obtained using the Strauss method. Late extrastimuli resulted in compensatory return cycles (zone I), increasing prematurity gave rise to less-than-compensatory return cycles (zone II or "plateau") and interpolation or echo responses occurred at shorter coupling intervals (zone III). The sinoatrial (SA) conduction time was defined as the difference between return cycle and postreturn cycle lengths that fell in the latter portion of zone II. The SA conduction time was similar to those derived from the Strauss method (r = 0.91, n = 17, p less than 0.01) and remained similar at the 2 pacing cycles, 172 +/- 52 ms (mean +/- standard deviation) at 739 +/- 71 ms (cycle 1) and 170 +/- 60 ms at 596 +/- 57 ms (cycle 2). In 4 patients, the atrial pacing method could unmask zone II. The SN refractory period was defined as the longest coupling interval at which zone III was apparent. It was compared at cycles 1 and 2 in 14 patients. There was a significant increase in the SN refractory period with faster pacing rates, from 406 +/- 104 ms (cycle 1) to 462 +/- 112 ms (cycle 2) (p less than 0.05). The atrial pacing method provides an alternative evaluation of SA conduction and may permit the study of drug effects at identical basic rates.

Adult↗