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Biomedical subjects

B Brembilla-Perrot

Publications and source records attributed to B Brembilla-Perrot.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Influence of time (4 years) on the results of programmed ventricular stimulation].

The reproducibility of programmed ventricular stimulation has been previously demonstrated for periods of a few hours to several months. It has not been studied over longer intervals. The aim of this study was to assess the reproducibility of the method at long-term (> 2 years). Forty-six patients with underlying cardiac disease underwent two programmed ventricular stimulations in the absence of antiarrhythmic treatment at intervals of 2 to 6 years (mean 4 years). None of the patients had myocardial infarction or cardiac surgery during this period. The protocol was identical: up to 3 extra-stimuli were delivered in the two right ventricular sites over 3 cycles. Twenty-eight patients had inducible sustained monomorphic ventricular tachycardia during the first investigation (Group I): the investigation was negative in the remaining 18 patients (Group II). During the second investigation, 26 of the 28 patients in Group I had inducible ventricular tachycardia, the rate of which decreased from 206 +/- 50 bpm to 196 +/- 54 bpm. The induced ventricular tachycardia was slower in 15 patients and faster in 5 patients. The mode of induction was different in 12 cases. In Group II, 4 patients (22%) had inducible sustained ventricular tachycardia at the second investigation. The authors conclude that the reproducibility of programmed ventricular stimulation remains good in the long-term in subjects within inducible tachycardia, demonstrating the stability of the arrhythmogenic substrate; the frequency of this tachycardia is generally slower. In subjects with an abnormal initial investigation who became symptomatic, it may be useful to repeat programmed ventricular stimulation.

Adult↗
PubMed1998

[Reproducibility of heart rate variability in the chronic phase of myocardial infarction].

Evaluation of heart rate variability is a common method of assessing autonomic nervous system function and its effects on heart rate in different conditions. The reproducibility of the technique is not known in the chronic phase of myocardial infarction. The aim of this study was therefore to assess the reproducibility of the measurement in 54 subjects who were clinically stable with no change in treatment at a distance from acute or semi-recent (> 2 years) myocardial infarction, after an interval of one month. The temporal and spectral analysis of heart rate variability included measurement of the standard deviation of the normal RR intervals (SDNN), on the mean heart rate, the percentage of RR intervals greater than 50 ms than the adjacent interval (pNN50), the coefficient of variability (CV), the square root of the differences between successive RR intervals (rMSSD), the power of low frequencies (LF) and high frequencies (HF) and of the fractional spectral power (LF/HF). No significant changes in these parameters were observed. Analysis of individual variations showed that the heart rate was the most stable parameter: for evaluation of vagal tone, the rMSSD showed less variability than the pNN50 and HF. The presence of cardiac disease did not influence these results. The authors conclude that parameters of evaluation of heart rate variability in temporal and spectral analysis are globally reproducible in stable subjects. However, individual values may change from one measurement to another. Nevertheless, abnormal variability is constantly observed at the second investigation and, similarly, normal variability also remains unchanged. These individual variations suggest that, for the demonstration of change in these parameters of variability with treatment, large population groups must be studied.

Adult↗
PubMed1998

[Polymorphous ventricular tachycardia occurring three months following radiofrequency ablation of the bundle of His].

The authors report the case of a 73-year-old patient presenting with polymorphous ventricular tachycardias one to 3 months after radiofrequency His bundle resection, as soon as the pacing frequency was reduced to 70 bpm. The clinical history revealed the existence of a possible clinical predisposition, as this patient had experienced an episode of torsade de pointe induced by hydroquinidine, one year previously. This case illustrates the importance of selecting a sufficiently high minimal stimulation frequency after His bundle resection.

Bundle of His↗
PubMed1998

[Alteration of sinus variability after cardiac surgery].

UNLABELLED: Sinus tachycardia is frequent after cardiac surgery and this tachycardia is probably due to changes of the autonomic nervous system. The objective of this study was to evaluate the changes possibly induced by cardiac surgery, by studying sinus variability (SV) during a 24-hour Holter monitoring. The examination was performed in 28 patients who had undergone cardiac surgery 1 to 6 weeks previously. These patients had no alteration of left ventricular function, or any causes likely to modify SV and they had a normal postoperative course. Their results were compared to those of 4 subjects developing a postoperative complication (1 case of ventricular tachycardia and 3 cases of resuscitated cardiac arrest). The results were also compared to those of 24 age-matched adult controls without heart disease (control group). The study of SV included temporal and spectral analysis of SV with measurement of the standard deviation of normal RR intervals (SD), mean heart rate (HR), percentage of RR intervals differing by more than 50 m/sec from the adjacent interval (pNN50), coefficient of variability (CV) (SD/RR), square root of the differences between successive RR (rMSSD), spectral properties of low frequencies (LF) and high frequencies (HF) and the fractionated spectral property (LF/HF). RESULTS: (see tables, page 151 and 152). An alteration of SV was therefore observed in the surgical group, and lasted 4 to 6 months after surgery. No difference was observed between subjects without cardiac events and those presenting a cardiac event. IN CONCLUSION: cardiac surgery decreases all parameters of SV during the first few postoperative months. Certain unexpected cardiac accidents during this period could be explained by these changes.

Adult↗
PubMed1998

[Evaluation of high amplification ECG and the study of sinus variability in the detection of patients at risk of sudden death].

In order to define the best strategy of prognostic evaluation in relation to patients in heart failure, 415 patients with impaired left ventricular function (ejection fraction < 40%) were prospectively included, between June 1993 and 1996, in a study comparing the respective value of high amplification ECG and Holter analysis of sinus variability, 308 patients in sinus rhythm and narrow QRS complexes were included. The patients were distributed into 4 groups according to the presence or absence of late potentials and altered sinus variability (group I with 2 normal examinations, group II with late potentials and normal variability, group III without late potentials, but with altered variability and group IV with 2 abnormal examinations). The sudden and overall mortality was significantly greater in groups III (28 and 11%) and IV (28 and 9%) than in group I (7 and 3%) and II (11 and 2%). The presence of potential was unable to identify patients at risk of ventricular tachycardia and sudden death. In another 60 patients with complete branch block, the prognosis was also correlated with the alteration of sinus variability. In conclusion, high amplification ECG correctly evaluated the prognosis of subjects in heart failure. However, analysis of sinus variability should be systematically proposed to detect subjects at high risk of mortality, whether the subject has large or narrow QRS complexes.

Adult↗
PubMed1997

The signal-averaged electrocardiogram is of limited value in patients with bundle branch block and dilated cardiomyopathy in predicting inducible ventricular tachycardia or death.

An abnormal signal-averaged electrocardiogram (SAECG) has predictive value for arrhythmic events in patients with idiopathic dilated cardiomyopathy and a normal conduction. The purpose of this study was to investigate whether the presence of a complete bundle branch block (BBB) affects prognostic information of the SAECG. We prospectively obtained SAECGs in 128 patients with idiopathic dilated cardiomyopathy. Forty-three of them had BBB and 85 had a normal QRS duration. According to their clinical history and results of ventricular programmed stimulation, patients were divided into 4 groups: (1) group IA with BBB and ventricular tachycardia (VT) (n = 18); (2) group IB with BBB but without VT (n = 25); (3) group IIA without BBB but with VT (n = 40); (4) group IIB without BBB and without VT (n = 45). Patients were compared with 129 patients without heart disease and without VT. Fifty-seven of them had BBB (group III) and 72 had normal conduction (group IV). The filtered QRS duration was longer in group IB than in group III (175 +/- 21 vs 149 +/- 16 ms, p <0.001), and in group IIB than in group IV (111 +/- 19 vs 96 +/- 12 ms, p <0.05). QRS duration was similar in groups IA and IB (176 +/- 24 vs 175 +/- 21 ms) but longer in group IIA than in group IIB (131 +/- 24 vs 111 +/- 19 ms, p <0.001). The low-amplitude signal duration (LAS) and the root-mean-square voltage (RMS) of the last 40 ms of the filtered QRS did not differ between groups IB and III and IA and IB. LAS and RMS were, respectively, longer (44 +/- 20 vs 31 +/- 13 ms, p <0.01) and lower (21 +/- 20 vs 43 +/- 33 microV, p <0.001) in groups IIA and IIB. In groups IA and IB the combination of 2 of the 3 available criteria: QRS duration >170 ms, RMS <20 microV, LAS >45 ms lead up to the best overall statistical result, with a sensitivity and specificity of 78% and 56%, respectively. In groups IIA and IIB, using conventional late potential criteria, the sensitivity and specificity of the SAECG for VT detection were 65% and 73%, respectively. The risk of sudden death was not predicted by the SAECG, and total cardiac mortality was only dependent on left ventricular ejection fraction. In conclusion, QRS duration was prolonged in all of the patients with a dilated cardiomyopathy compared with those without heart disease. BBB did not change the sensitivity but decreased the specificity of the SAECG to predict any VT risk in dilated cardiomyopathy. The risk of sudden death and total cardiac mortality could not be predicted by the SAECG.

Adult↗
PubMed1997

Incomplete bundle-branch block and ST-segment elevation: syndrome associated with sustained monomorphic ventricular tachycardia in patients with apparently normal heart.

This paper reports on three cases of patients with an apparently normal heart admitted for sustained monomorphic ventricular tachycardia. The only abnormal finding showed in the electrocardiogram (ECG) in sinus rhythm that exhibited an entity associated with incomplete right bundle-branch block and persistent ST-segment elevation. The ECG entity was variable and disappeared transiently. Spontaneous ventricular tachycardia in one patient was inducible by programmed stimulation. There was no underlying heart disease. The origin of the ventricular tachycardia in one patient was located by pace mapping in the left ventricle at the left ventricular basal septum. The follow-up (from 6 months up to 6 years) demonstrated a good prognosis. This particular ECG entity associated with monomorphic ventricular tachycardia could have been missed because of the variations in the ECG in sinus rhythm and was associated with a favorable prognosis.

Adult↗
PubMed1997

The acute effects of intravenously administered mibefradil, a new calcium antagonist, on the electrophysiologic characteristics of the human heart.

OBJECTIVE: This multicenter, double-blind, placebo-controlled, parallel-group study was designed to assess the acute effects of intravenous mibefradil on the electrophysiologic characteristics of the human heart. METHODS: Seventy-one patients referred for routine electrophysiologic testing were randomized to receive one of three intravenous treatments: placebo n = 23, 15 mg mibefradil in 15 min followed by 25 mg in 60 min (group 1, n = 24), or 35 mg mibefradil in 15 min followed by 45 mg in 60 min (group 2, n = 24). Electrophysiologic evaluations were performed prior to study drug administration and 30 min after the start of the infusion. Plasma samples were obtained at the start of the infusion and after 15, 75, and 105 min. RESULTS: Sinus node recovery time decreased significantly in Group 1 patients (-103 ms). Corrected sinus node recovery time in group 2 patients was 68.7 ms (P = 0.053). Compared to placebo, mibefradil produced mild but significant slowing of conduction in group 2 patients as manifested by an increase in the AH interval of 6.7 ms. Atrioventricular (AV) nodal refractoriness was increased, as indicated by a prolongation of the Wenckebach point in patients in both group 1 (32.1 ms) and group 2 (32.5 ms), compared to placebo. All adverse events were classified as mild to moderate and only one event (vasovagal attack) was considered to be treatment related. CONCLUSIONS: At plasma levels close to those found after chronic oral administration of 50 and 100 mg mibefradil, the higher dose produced an increase in corrected sinus node recovery time. Mibefradil also produced small but significant effects on AV nodal conduction and increased AV nodal refractoriness. Mibefradil had no effect on any other electrophysiologic parameter and was well tolerated.

Benzimidazoles↗
PubMed1997

Hypertrophic cardiomyopathy: value of atrial programmed electrical stimulation in patients with or without syncope with special reference to the role of atrial arrhythmias.

Hypertrophic cardiomyopathy may be associated with both supraventricular and ventricular arrhythmias, which may play a role in the genesis of syncope. The aim of this study was to assess the findings of electrophysiological study and programmed atrial and ventricular stimulation and their possible role in syncope. Programmed atrial and ventricular stimulation using up to two extrastimuli in right atrium and three in right ventricle at three cycle lengths (600, 400 ms and spontaneous) was systematically performed in 56 patients with hypertrophic cardiomyopathy. Thirty seven had unexplained dizzinesses or syncopes (group I) and 19 did not present loss of consciousness (group II). Patients with syncopes had a higher prevalence of induced sustained supraventricular tachyarrhythmia (73%) than those of group II (16%) (P<0.05). Inducible supraventricular tachycardia was the only finding in 16 patients with syncopes. During the follow-up (3 years+/-6 months), empirical antiarrhythmic therapy suppressed the symptoms, except in two patients who developed atrial fibrillation despite therapy. The high incidence of inducible atrial tachycardia of these patients was not correlated with particular Holter findings or echocardiographic data. However, their mean age was rather high (58+/-12 years). In conclusion, atrial tachyarrhythmias may play a role in syncopes of middle-aged patients with hypertrophic cardiomyopathy. Moreover programmed atrial stimulation is an useful means to identify this syncope mechanism.

Adult↗
PubMed1997

Relationships between heart rate variability and antiarrhythmic effects of hydroquinidine.

Class I antiarrhythmic drugs may increase the incidence of cardiac death, and controlled treatment is required in patients with severe ventricular arrhythmias. Electrophysiologically guided antiarrhythmic therapy remains an important method to manage patients with sustained ventricular tachycardia (VT). The purpose of the study was to evaluate the correlations between baseline heart rate variability in ambulatory electrocardiographic recordings of patients with sustained ventricular tachycardia and the response to hydroquinidine on VT inducibility, and to look for the changes in heart rate variability during hydroquinidine treatment. Thirty-five patients with spontaneous and inducible sustained VT were studied. Programmed ventricular stimulation and time and frequency domain analysis of heart rate variability were studied in the control state and 9-12 days after treatment with 300-600 mg of hydroquinidine. In 11 patients (group I), hydroquinidine prevented VT induction. In 24 patients (group II), sustained VT remained inducible during treatment with hydroquinidine. In the control state, heart rate variability was similar in both groups. During treatment with hydroquinidine, heart rate variability tended to decrease in groups I and II, but the changes were significant only in group II: the coefficient of variance (CV) decreased from 13 +/- 4% to 10% +/- 3% (p < 0.01) and low frequency/high frequency amplitude ratio decreased from 4.6 +/- 3.3 to 2.87 +/- 2.42 (p < 0.05). In conclusion, baseline heart rate variability does not differentiate the responders and nonresponders to hydroquinidine. Hydroquinidine decreases heart rate variability in all patients, but principally in those with still inducible VT.

Adult↗
PubMed1997

Bradycardia-induced polymorphic ventricular tachycardia after radiofrequency catheter modification of atrioventricular junction.

We report the case of a 59-year-old man with a dilated nonischemic cardiomyopathy who had chronic rapid atrial fibrillation despite several therapies. Radiofrequency modification of the atrioventricular (AV) junction slowed the mean ventricular rate from 120 beats per minute (bpm) to 60 bpm. Five hours after the procedure and during the following 1 week, despite ventricular pacing at 90 bpm, the patient developed nonsustained or sustained polymorphic ventricular tachycardias. Finally, pacing at 90 bpm was successfully used in this patient. In conclusion, patients who have undergone modification of AV conduction may be at high risk of life-threatening ventricular arrhythmias in the first week following the procedure.

Atrioventricular Node↗
PubMed1997

Mechanism of QRS electrical alternans.

In patients with latent dual atrioventricular nodal pathways a 2:1 ventriculoatrial block often occurs during ventricular pacing and is generally associated with the concomitant appearance of QRS alternans. This type of QRS alternans is related to retrograde conduction, and a concealed retrograde conduction in the His Purkinje system could explain the QRS alternans. A case that confirms the hypothesis that electrical alternans is secondary to a 2:1 block in the activation of some part of the ventricles is reported.

Cardiac Pacing, Artificial↗
PubMed1997

[Quinidine and high-amplification ECG].

High-amplification ECG (HA ECG) is now used routinely to evaluate ventricular tachycardia. The effects of 300 to 600 mg quinidine were determined in 26 heart disease patients with spontaneous and inducible ventricular tachycardia. Programmed ventricular stimulation was performed and an HA ECG recorded (40 Hz high-pass filter) before and under treatment. The stimulation became negative under treatment in nine patients (group I), whereas the 17 others had persistent inducible tachycardia (group II). HA ECG tracings were modified in groups I and II, with a QRS duration increase of 7% and 8%, respectively, and RMS 40 decrease of 37% and 29%, and an LAS increase of 16% and 17%. Furthermore, one of the three group I and four of the seven group II patients who had a normal HA ECG tracing before treatment developed HA ECG abnormalities under treatment. An arrhythmia-inducing effect of the treatment was noted in three group II patients; this effect was not detected by HA ECG. In conclusion, changes in HA ECG tracings were seen during quinidine therapy of patients with ventricular tachycardia, and this effect was independent from the effect of antiarrhythmic agents on induction of the ventricular tachycardia. In addition, abnormalities of high-amplification ECG tracings developed in some patients under quinidine therapy. These data suggest that class I antiarrhythmic agents modify high-amplification ECG tracings and that these modifications fail to predict whether the treatment will prove effective.

Adult↗
PubMed1997

[Possible mechanisms of false positive results of averaged ECG].

UNLABELLED: The objective of this retrospective study was to investigate the causes of high amplification (HA) ECG abnormalities detected in apparently healthy subjects. This study was based on 14 patients derived from a population of 167 admitted for assessment of malaise or supraventricular tachycardia and who had no apparent heart disease. The surface ECG showed fine QRS complexes (< 120 ms) with no left hemiblock on ECG. All of these subjects underwent a complete electrophysiological study and high amplification ECG using a 40 Hertz high-pass filter. For these 14 patients, the amplitude of the last 40 milliseconds (ms) of the mean QRS (RMS 40) was less than or equal to 20 microvolts (microV). Eight of them also had a duration of the terminal part of the QRS complex less than 40 microV (LAS) greater than 40 ms and 6 others had and LAS greater than 35 ms. The mean QRS interval was normal in all patients (< 120 ms). The usual causes for reduction of the RMS 40-were eliminated: programmed ventricular pacing using 3 extrastimuli under basal conditions and with isuprel remained negative. E chocardiography and the right ventricular angiography were normal. The surface ECG showed slight abnormalities: absence of Q wave in V6 without delay of the intrinsic-like deflection in 3 subjects, increased R wave in V1 in 2 subjects and especially deep S wave in V5-V6 with no left axis deviation in 10 patients. Programmed or increasing frequency atrial pacing induced RBB or LBB in 13 of these 14 subjects (RBB: 7, LBB : 3, RBB and LBB:3). Follow-up, ranging from 6 months to 3 years, did not reveal any cardiac events, but signs of RBB appeared in 3 patients and signs of LBB were observed in 1 patient. IN CONCLUSION: an abnormal high amplification ECG in apparently healthy subjects could be explained by minor conduction disorders essentially in the right branch. The presence of a deep S wave (> 2 mm) in V5-V6 is the commonest ECG sign in these subjects. This diagnosis can only be proposed after exclusion of right ventricular dysplasia in symptomatic patients.

Adult↗
PubMed1997

[Comparative study of cibenzoline and flecainide by oral route for preventing recurrence of paroxysmal atrial tachyarrhythmias].

Although paroxysmal atrial arrhythmias are the commonest form of arrhythmia, their therapeutic management still remains controversial. Seventy one patients were included in a multicentre, randomized double-blind, double-placebo study, in parallel groups (37 in group C and 34 in group F) to compare the efficacy of cibenzoline (C) and flecainide (F), administered orally, in the prevention of recurrent atrial arrhythmia. The arrhythmia usually consisted of atrial fibrillation (n = 65), while 6 patients presented with paroxysmal atrial flutter. The mean daily dosages were 221 +/- 60 mg (C) and 165 +/- 49 mg (F). The mean age was 63 +/- 12 years in group C and 63 +/- 16 years in group F. In this trial, atrial arrhythmia was idiopathic in almost two-thirds of cases. The duration of follow-up of this study was 6 months, during which recurrences of arrhythmia were evaluated in terms of the symptoms experienced and in terms of ECG and Holter examinations repeated at the 3rd and 6th months. Supplementary ECG and Holter examinations were also performed in the presence of a clinical suspicion of recurrent symptoms. Comparison of the percentages of patients not developing a documented recurrence and who tolerated treatment, by Kaplan-Meler curves, showed a significant difference between cibenzoline (58%) and flecainide (56%). In the not-responders, the mean time to recurrence was 75 +/- 48 days in group C and 75 +/- 62 days in group F(NS). Six patients dropped out of the trial because of adverse events, including 3 cardiac adverse events (2 case of ventricular proarrhythmic activity). Four extracardiac adverse events led to discontinuation of treatment in group C. In conclusion, the efficacy of cibenzoline and flecainlde in the secondary prevention of atrial arrhythmia was found to be comparable, with 58% and 58% of patients in sinus rhythm, respectively, with a follow-up of 6 months.

Anti-Arrhythmia Agents↗
PubMed1997

[Influence of anti-arrhythmia agents on heart rate variability].

UNLABELLED: Since analysis of heart rate variability (HRV) is able to identify subjects at risk of sudden death and as antiarrhythmics can interfere with this prognosis, the objective of this study was to determine whether antiarrhythmics (AA) modified the HRV measured on a 24-hour Holter recording and after rapid ventricular stimulation and whether the initial HRV and its possible modification during treatment with AA were correlated with the results of AA treatment in patients with ventricular tachycardia (sustained VT). The HRV was studied in 50 patients with heart disease and spontaneous sustained VT, reproduced by programmed ventricular stimulation. This analysis was performed at baseline with antiarrhythmic treatment consisting of low-dose beta-blocker and quinidines in 26 patients (group I) or amiodarone in 24 patients (group II). Treatment was effective (i.e. prevented induction of VT) in 9 patients in group I (group la) and 5 patients in group II (group IIa). Treatment was ineffective in the other 17 patients of group I (group Ib) and 19 patients of group II (group IIb). The initial HRV was similar in the patients of groups Ia and Ib or groups IIa and IIb. Temporal analysis did not reveal any significant variation of HRV during AA treatment. In contrast, spectral analysis of HRV and the HRV observed during ventricular stimulation demonstrated a significant reduction of this parameter (p < 0.05 for groups I and II combined). IN CONCLUSION: the initial HRV is not predictive of the results of treatment. Quinidines and amiodarone tend to decrease HRV regardless of the effect of the AA on the prevention of VT.

Adrenergic beta-Antagonists↗
PubMed1997

[Tilt-table test. Value in children and adolescents].

The tilt test is a non-invasive investigation which reproduces malaises or vagal syncope. This is a common condition in children and adolescents and the value of this investigation in this population is therefore self-evident. The tilt test was performed from 4 years of age in 105 children aged 4 to 18 years (mean 10 +/- 4 years) who had suffered one or several malaises with syncope. This test, using a resting period of 20 minutes, then a tilt of 70-80 degrees for 40 minutes, was considered to be positive if the symptoms could be reproduced or if the heart rate slowed to less than 50/min or if the blood pressure fell by more than 30 mmHg. The test was positive in 46 children (44%). Ten remained asymptomatic but had significant reductions in blood pressure: 36 children reproduced their symptoms. The positivity was related to a cardio-inhibitory response in 4 cases, vasodepressive in 20 cases, mixed in 20 cases and "psychiatric" in 2 cases: sinus tachycardia preceded positivity in 43 of the 46 cases. Only 21 children were treated either by disopyramide (12 cases) or betablockers (9 cases). All but one of the children became asymptomatic but the tilt test remained positive in 7 of the 9 patients treated with betablockers and in 3 children treated with disopyramide. The essential value of this investigation was to stop investigations in positive cases, to reassure parents and the children and to allow the pursuit of sporting activities. The authors conclude that the tilt test is an investigation easy to carry out in the young child and which spares complementary investigation in cases of positivity and guides medical treatment.

Adolescent↗