Biomedical subjects

R Tavernier

Publications and source records attributed to R Tavernier.

At least 19 recordsLinked to original sources

PubMed2006

Intravenous amiodarone treatment in horses with chronic atrial fibrillation.

Six horses without underlying cardiac disease were presented because of atrial fibrillation of between 5 and 12 months duration. These horses received an intravenous amiodarone treatment of 5mg/kg/h for 1 h followed by 0.83mg/kg/h for 23h and subsequently 1.9mg/kg/h for 30h. During treatment, clinical signs were monitored and a surface ECG and an intra-atrial electrogram were recorded. Infusion was discontinued when sinus rhythm or side effects occurred. Four horses successfully cardioverted, of which one showed symptoms of hind limb weakness and weight shifting. Two horses did not cardiovert and showed similar side effects. In all horses, side effects disappeared within 6h after termination of treatment. Cardiac side effects, such as pro-arrhythmia, were not seen in any of the horses. Total bilirubin slightly increased in three horses and normalised within four days. It was concluded that amiodarone has the potential to treat naturally occurring chronic atrial fibrillation in horses, although further research is needed to refine the infusion protocol.

Amiodarone↗

PubMed2005

Coronary risk factors and inflammation in patients with coronary artery disease and internal cardioverter defibrillator implants.

BACKGROUND: The internal cardioverter defibrillator (ICD) is increasingly used to treat ventricular tachyarrhythmias in patients with coronary artery disease (CAD). The burden of coronary risk factors and inflammation is however not well studied in these high risk patients. STUDY AIMS: The aim of the present study was to describe the prevalence of coronary risk factors (including lipid values) and inflammation (including high sensitive-C-reactive protein, hs-CRP) in patients with CAD and ICD implants. METHODS: Baseline clinical characteristics and laboratory results of all eligible patients for the Cholesterol Lowering and Arrhythmias Recurrences after Internal Defibrillator Implantation trial (CLARIDI trial) were used. All patients had documented CAD, an ICD implant and were not yet treated with statins. Coronary risk factors, lipid values, glycated haemoglobin (HbA(1c)) and hs-CRP levels were determined. RESULTS: In the 110 included patients (mean age 68+/-9 years, LVEF 40+/-17%, NYHA class II-III in 47%), a high prevalence of coronary risk factors was documented: current smoking in 18%, body mass index > or =30 kg/m(2) in 16%, blood pressure > or =140/90 mm Hg in 40%, history of diabetes in 12%, and HbA(1c) > or =6% in 16% of patients not known with diabetes. A total cholesterol >175 mg/dl was found in 76% of patients and an LDL cholesterol >100 mg/dl in 83%. Finally, median hs-CRP was 4.8 mg/l (interquartile range 2.5-13.9 mg/l). Hs-CRP values > or =2 mg/l were noted in 83% of all patients and in 68% of patients who had an ICD implant more than 6 months before inclusion. CONCLUSION: In CAD patients with ICD implants, the burden of coronary risk factors is high, often unrecognized and/or under-treated. Persistent inflammation is found in the majority of these patients.

Adult↗

PubMed2005

Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse.

Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These periods of profound bradycardia were corrected by temporary right ventricular pacing until spontaneous conduction resumed. It is concluded that temporary right ventricular pacing should be available during electrical cardioversion of atrial fibrillation in horses.

Animals↗

PubMed2003

Initiating mechanisms of paroxysmal atrial fibrillation.

BACKGROUND: The understanding of the onset mechanisms of paroxysmal atrial fibrillation (AF) may help to develop preventive therapy. Specific heart rate (HR) patterns and autonomic changes immediately before the onset of paroxysmal AF are not fully investigated. We undertook the present study to assess HR and heart rate variability (HRV) changes before the onset of AF using 24-h Holter electrocardiographic analysis in patients without antiarrhythmic medication. METHODS AND RESULTS: In 27 patients, 48 episodes of AF, lasting more than 30s and preceded by sinus rhythm for more than 1h were analysed. The hour preceding AF was divided in 5- and 30 min blocks. HR was also analysed in the last 15 beats. In 21% of the episodes, HR decreased >or=5% in the last 5 min (defined as deceleration); it increased >or=5% in 37% (defined as acceleration). HR, standard deviation (SD) and SD corrected for RR interval changed significantly in the last 5 min in the total group. Acceleration and deceleration were already visible over 30-min blocks in both these subgroups; changes in SD were only seen in the accelerators. The number of atrial premature beats (PACs) increased before AF, most clearly in the accelerators. Spectral HRV analysis revealed no additional information. CONCLUSIONS: Changes in HR, SD, and an increased number of PACs herald AF from at least 30 min before onset, more pronounced in accelerators. Spectral HRV parameters are not useful to foresee AF onset. This has possible implications for device therapy.

Atrial Fibrillation↗

PubMed2002

Implantation of a dual-chamber, rate-adaptive pacemaker in a horse with suspected sick sinus syndrome.

A five-year-old gelding suffered syncope at the end of a period of exercise. A 24-hour electrocardiogram recording revealed intermittent pauses in the sinus rhythm of up to 10 seconds, indicating sinus node disease; the pauses occurred repeatedly, particularly after exercise. A dual-chamber, rate-adaptive pacemaker was successfully implanted, which prevented excessive postexercise bradycardia and syncope, and allowed the horse to return to work.

Animals↗

PubMed2002

An equine model of chronic atrial fibrillation: methodology.

We describe the development and the different features of an experimental model of chronic atrial fibrillation (AF) in equines. In four healthy ponies a dual-chamber pacemaker, with an adapted pacemaker program, was implanted transvenously in the standing animal. This adapted pacemaker induced episodes of AF by delivering a 2s burst of electrical stimuli (42 Hz) as soon as sinus rhythm was detected. Simultaneous with a surface electrocardiogram, the intra-atrial electrogram could be recorded to determine the atrial electrogram morphology. Programmed electrical stimulation (PES) was used to determine the atrial effective refractory period (AERP) and the rate adaptation of the AERP, the sinus node recovery time (SNRT) and the corrected SNRT, AF vulnerability, AF cycle length and AF duration. This experimental AF model can be used to study the pathophysiology of chronic AF in equines.

Animals↗

PubMed2001

Determinants of sudden death after discharge from hospital for myocardial infarction in the thrombolytic era.

AIMS: The purpose of this study was to assess risk factors for sudden death after discharge from hospital for myocardial infarction in an era in which 50% of patients receive thrombolytic drugs. METHODS AND RESULTS: We prospectively studied 708 consecutive survivors of myocardial infarction admitted to hospitals, which had registered their clinical, functional, and electrical parameters. A total of 83 patients died in the first 2 years (12%) after discharge. Sudden death was only observed in 12 patients. In multivariate analysis only NYHA class >I, and a filtered QRS duration > or =110 ms were important predictive variables for sudden death. A pre-defined high-risk group of 25 patients had no sudden death. When the strongest predictive variables in univariate analysis were combined to increase the positive predictive value for sudden death, we only achieved a maximal value of 27%. CONCLUSIONS: In an unselected infarction population, the risk for sudden death is low in the first 2 years. Therefore, prediction and prophylactic intervention, such as defibrillator therapy become difficult. The event is related to cardiac dysfunction on admission, and with abnormalities in the filtered electrocardiogram.

Adult↗

PubMed2001

Long term results of cardioverter-defibrillator implantation in patients with right ventricular dysplasia and malignant ventricular tachyarrhythmias.

OBJECTIVE: To study the outcome of patients with arrhythmogenic right ventricular dysplasia treated with an implantable cardioverter-defibrillator (ICD) for ventricular tachyarrhythmias complicated by haemodynamic collapse. DESIGN: Observational study. SETTING: University hospital. PATIENTS: Nine consecutive patients (eight male, one female; mean (SD) age, 36 (18) years) with arrhythmogenic right ventricular dysplasia presenting with ventricular tachycardia and haemodynamic collapse (n = 6) or ventricular fibrillation (n = 3), treated with an ICD. MAIN OUTCOME MEASURES: Survival; numbers of and reasons for appropriate and inappropriate ICD interventions. RESULTS: After a mean (SD) follow up of 32 (24) months, all patients were alive. Six patients received a median of 19 (range 2-306) appropriate ICD interventions for events detected in the ventricular tachycardia window; four received a median of 2 (range 1-19) appropriate ICD interventions for events detected in the ventricular fibrillation window. Inappropriate interventions were seen for sinus tachycardia (18 episodes in three patients), atrial fibrillation (three episodes in one patient), and for non-sustained polymorphic ventricular tachycardia (one episode in one patient). CONCLUSIONS: Patients with arrhythmogenic right ventricular dysplasia and malignant ventricular arrhythmias have a high recurrence rate requiring appropriate ICD interventions, but they also often have inappropriate interventions. Programming the device is difficult because this population develops supraventricular and ventricular tachyarrhythmias with similar rates.

Adult↗

PubMed2000

Heart rate dynamics at the onset of ventricular tachyarrhythmias as retrieved from implantable cardioverter-defibrillators in patients with coronary artery disease.

BACKGROUND: The recent availability of implantable cardioverter-defibrillators (ICDs) that record 1024 R-R intervals preceding a ventricular tachyarrhythmia (VTA) provides a unique opportunity to analyze heart rate variability (HRV) before the onset of VTA. METHODS AND RESULTS: Fifty-eight post-myocardial infarction patients with an implanted ICD for recurrent VTA provided 2 sets of 98 heart rate recordings in sinus rhythm: (1) before a VTA and (2) during control conditions. Three subgroups were considered according to the antiarrhythmic (AA) drug regimen. A state of sympathoexcitation was suggested by the significant reduction in HRV before VTA onset compared with control conditions. beta-Blockers and dl-sotalol enhanced HRV in control recordings; nevertheless, HRV declined before VTA independent of AA drugs. A gradual increase in heart rate and decrease in sinus arrhythmia at VTA onset were specific findings of patients who received dl-sotalol. CONCLUSIONS: The peculiar heart rate dynamics observed before VTA onset are suggestive of a state of sympathoexcitation that is independent of AA drugs.

Adrenergic beta-Antagonists↗

PubMed2000

Infarct size and recurrence of ventricular arrhythmias after defibrillator implantation.

Infarct size as determined by perfusion imaging is an independent predictor of mortality after implantable cardioverter defibrillator (ICD) implantation in patients with coronary artery disease (CAD) and life-threatening ventricular arrhythmias (VA). However, its value as a predictor of VA recurrence and hospitalisation after ICD implantation is unknown. Therefore, the objective of this study was to evaluate whether infarct size as determined by perfusion imaging can help to identify patients who are at high risk for recurrence of VA and hospitalisation after ICD implantation. We studied 56 patients with CAD and life-threatening VA. Before ICD implantation, all patients underwent a uniform study protocol including a thallium-201 stress-redistribution perfusion study. A defect score as a measurement of infarct size was calculated using a 17-segment 5-point scoring system. Study endpoints during follow-up were documented episodes of appropriate anti-tachycardia pacing and/or shocks for VA and cardiac hospitalisation for electrical storm (defined as three or more appropriate ICD interventions within 24 h), heart failure or angina. After a mean follow-up of 470+/-308 days, 22 patients (39%) had recurrences of VA. In univariate analysis, predictors for recurrence were: (a) ventricular tachycardia (VT) as the initial presenting arrhythmia (86% vs 59% for patients without ICD therapy, P=0.04), (b) treatment with beta-blockers (36% vs 68%, P=0.03) and (c) a defect score (DS) > or = 20 (64% vs 32%, P=0.03). In multivariate analysis, VT as the presenting arrhythmia (chi2=5.51, P=0.02) and a DS > or = 20 (chi2=4.22, P=0.04) remained independent predictors. Cardiac hospitalisation was more frequent in patients with a DS > or = 20 (44% vs 13% for patients with DS < 20, P=0.015) and this was particularly due to more frequent hospitalisations for electrical storm (24% vs 3% for patients with DS < 20, P=0.037). The extent of scarring determined by perfusion imaging can separate patients with CAD into high- and low-risk groups for recurrence of VA and cardiac hospitalisation after ICD implantation.

Adrenergic beta-Antagonists↗

PubMed2000

Lipid lowering drugs and recurrences of life-threatening ventricular arrhythmias in high-risk patients.

OBJECTIVES: To evaluate a possible effect of lipid lowering drugs on recurrences of ventricular arrhythmias (VA) after implantable cardioverter defibrillator (ICD) implantation. BACKGROUND: In patients with coronary artery disease (CAD), lipid lowering drugs reduce total and sudden cardiac death. Because the mechanism is not completely understood, we studied whether these drugs have a favorable influence on the occurrence of life-threatening VA in patients with CAD and ICD implants. METHODS: We conducted an observational study in 78 patients with CAD and life-threatening VA, treated with an ICD. After ICD implantation, 27 patients were on treatment with lipid lowering drugs (group I) and 51 were not (group II). Patients were studied for the following end points: recurrences of VA requiring ICD intervention, cardiac death and hospitalization. RESULTS: After a mean follow-up of 490 +/- 319 days, 35 patients (45%) had recurrences of VA requiring ICD intervention. In multivariate analysis, the use of lipid lowering drugs (chi-square 6.33, p = 0.012) and poorly tolerated sustained monomorphic ventricular tachycardia as initial presentation (chi-square 4.84, p = 0.028) remained as independent predictors of recurrences of VA. Patients in groups I and II had similar baseline clinical characteristics, but patients in group I had a lower incidence of recurrences of VA (6/27 or 22% vs. 29/51 or 57%, p = 0.004) and of the combined end points of cardiac death and hospitalization (4/27 or 15% vs. 23/51 or 45%, p = 0.015) compared with patients in group II. CONCLUSIONS: This is the first observation that the use of lipid lowering drugs is associated with a reduction of recurrences of VA in patients with CAD and ICD implants. These data require confirmation in a prospective randomized trial.

Aged↗

PubMed2000

Use of an implantable cardioverter defibrillator in a patient with two implanted neurostimulators for severe Parkinson's disease.

We report a patient with Parkinson's disease treated with two pectorally implanted neurostimulators (NSs) who presented with a life-threatening ventricular tachyarrhythmia in whom an abdominal ICD was implanted. Testing during implantation showed that the NS did not affect the bipolar sensing of the ICD, even when the NSs were set at a frequency of 130 pulses/s with an output of 5 V and pulse width of 0.21 ms in a bipolar and a unipolar configuration. The ICD shock, however, did affect both NSs: there was a reset to the output Off state and there was a reset of the electrode polarities.

Defibrillators, Implantable↗

PubMed2000

Prevalence of potential candidates for biventricular pacing among patients with known coronary artery disease: a prospective registry from a single center.

New forms of ventricular pacing are increasingly studied as an option in the management of patients with heart failure. Coronary artery disease (CAD) is the most frequent cause of heart failure, and patients with complete left or right bundle branch block (LBBB and RBBB) and a reduced left ventricular ejection fraction (LVEF) are the best candidates for this new therapy. However, the prevalence of this clinical presentation is uncertain. During a 1-year period, 433 patients with documented CAD (mean age 64 +/- 10 years, 79% men) who were referred for myocardial perfusion imaging were prospectively studied. All patients underwent a 2-day stress-rest gated 99mTc-Tetrofosmin SPECT study with evaluation of resting LV enddiastolic (LVEDV) and endsystolic (LVESV) volumes and LVEF. The resting ECG was examined in all patients for the presence of complete LBBB or RBBB. Of the 433 patients with CAD 36 patients (8.3%) had LBBB (n = 14) or RBBB (n = 22) and a QRS width > 120 ms. These 36 patients were in general older and more frequently had diabetes and atrial fibrillation. Patients with LBBB or RBBB had a significantly lower LVEF (41 +/- 16% vs 48 +/- 14%, P < 0.01) and significantly higher LV volumes compared to patients without LBBB or RBBB (177 +/- 79 mL vs 131 +/- 53 mL, P < 0.001 for LVEDV and 116 +/- 76 mL vs 73 +/- 49 mL, P < 0.001 for LVESV). In total, 112/433 (26%) had an LVEF < or = 40%; 16 had also a LBBB or RBBB (3.7% of the whole population, 14% of the patients with a LVEF < or = 40%). Within the group of patients with a LVEF > or = 40%, patients with BBB had comparable LVEF (26 +/- 9% vs 30 +/- 8%, P = NS) but significantly higher LVEDV and LVESV (230 +/- 70 mL vs 190 +/- 64 mL, P < 0.05 for LVEDV and 170 +/- 65 mL vs 135 +/- 56 mL, P < 0.05 for LVESV). In this prospective registry 3.7% of all patients with known CAD had LBBB or RBBB in combination with a LVEF < or = 40%. This represented 14% of all patients with a LVEF > or = 40%. These limited numbers should be kept in mind when considering biventricular pacing as a new therapeutic options in patients with heart failure.

Aged↗

PubMed2000

Atrial overdriving is beneficial in patients with atrial arrhythmias: first results of the PROVE Study.

The AF Prevention by Overdriving (PROVE) trial is an ongoing prospective study of the effectiveness of atrial overdrive pacing combined with an Automatic Rest Rate function in the prevention of atrial arrhythmias. All patients who have received a Talent DR 213 pacemaker are eligible for enrollment into the study. After a 1-month monitoring period, the patients are divided into two groups. Group I includes patients with > or = 2 appropriate mode-switch (MS) episodes, or 1 MS episode of > or = 10 minutes, and/or > 300 atrial runs of > 5 beats/month. Group II includes all other patients. The number and duration of atrial arrhythmias are measured the pacemaker's Automatic Interpretation and Data Analysis software (AIDA). Patients' quality-of-life is measured by a validated functional status questionnaire. After having been grouped, the patients are randomly assigned, in a crossover design, to standard DDDR or overdrive pacing + Rest Rate, each programmed for a 3-month period. Preliminary results in 78 patients show a 34% reduction in the mean number of MS, and a mean 48% shortening of the overall duration of the episodes by overdrive pacing + Rest Rate, achieved by a mean 84% prevalence of atrial pacing. Overdrive pacing + Rest Rate was well tolerated and associated with a slight improvement in quality-of-life.

Aged↗

PubMed2000

Factors determining long-term outcomes and survival in patients with coronary artery disease and ventricular tachyarrhythmias: a single center experience.

A Single-Center Experience. The influence, after ICD implantation, of concomitant CABG, angioplasty, and other antiischemic therapeutic interventions, like treatment with beta-blockers, on outcome and mortality of patients with VT or VF due to CAD remains uncertain. The univariate and multivariate risks of recurrence of ventricular arrhythmias requiring ICD interventions or death associated with baseline clinical and functional variables were studied in 160 consecutive patients with CAD of whom 30 underwent CABG or angioplasty at < or = 2 weeks before ICD implantation. ICD interventions occurred in 98 (61%) patients over a mean follow-up of 1,065 days. In univariate and multivariate analysis, VT as the presenting arrhythmia was the only clinical factor predictive of recurrences. Treatment with beta-blockers at hospital discharge reduced the probability of recurrences. Kaplan-Meier analysis confirmed the effect of beta-blockers (P < 0.005) and of VT as the presenting arrhythmia (P < 0.01). Overall mortality was 61% (29/160). In multivariate analysis a low ejection fraction (< or = 0.20) and omission of angiotensin-converting enzyme inhibitors at discharge were associated with excess mortality. In Kaplan-Meier analysis, a low ejection fraction (borderline between 0.30 and 0.21, significant < 0.21) was the single predictor of mortality. Revascularization by CABG or angioplasty had no influence on ventricular arrhythmia recurrences or survival. During long-term follow-up, VT as the presenting arrhythmia and the omission of beta-blocker therapy were associated with excess recurrences of ventricular arrhythmias after ICD implantation. In contrast, survival depended primarily on left ventricular function at discharge. Revascularization did not prevent recurrences of arrhythmias and had no significant effect on survival in the small group of patients who underwent CABG or angioplasty.

Adrenergic beta-Antagonists↗

PubMed2000

Pacing induced sustained atrial fibrillation in a pony.

A transvenous, screw-in electrode was implanted in the right atrium of a healthy pony and connected with an implantable pulse generator programmed to deliver bursts of electrical stimuli to the atrium. Initially, cessation of burst pacing resulted in short (less than 1 minute), self-terminating episodes of atrial fibrillation. As burst pacing continued, the episodes of induced atrial fibrillation became longer. After 3 weeks of continuous atrial pacing, atrial fibrillation became sustained (56 hours). This model of pacing induced atrial fibrillation can be used to study the mechanisms leading to atrial fibrillation, its perpetuation and therapy. Our preliminary observations support the concept that once atrial fibrillation starts, it sets up changes in the electrical characteristics of the atrium that favor its own perpetuation.

Animals↗

PubMed2000

[Clinical evaluation of a dual chamber implantable cardioverter-defibrillator].

Single-chamber ventricular cardioverter-defibrillator (ICD) has been shown to significantly reduce the incidence of sudden cardiac death due to malignant ventricular arrhythmias. However, inappropriate therapy due to supraventricular tachyarrhythmias (mainly atrial fibrillation) affects up to 34% of patients. Moreover, it has been estimated that up to 20% of ICD patients are in the need of physiological antibradycardia pacing. Use of dual-chamber ICD offers an atrial signal for better ability to discriminate atrial from ventricular tachyarrhythmias as well as a maintenance of AV synchrony, what may be of critical importance for patients with a compromised left ventricular function. In the present study we describe our preliminary clinical experience with a dual-chamber ICD's implanted in 20 patients. During the implantation and in-hospital testing, 95 induced VT/VF episodes were correctly diagnosed by ICD, as well as 28 induced FA episodes. Over a mean follow-up period of 10 +/- 6 months, 98 tachycardia episodes were recorded. All 76 VT/VF episodes were correctly diagnosed, as were 18 of 22 FA. Four FA episodes were diagnosed as VT/VF and treated by antitachycardia pacing in 2 cases and by shock in 2. Thus, sensitivity and specificity of VT/VF detection are 100% and 82% respectively. A dual-chamber ICD appears to improve discrimination of atrial from ventricular tachyarrhythmias without loss of sensitivity and to decrease occurrence of inappropriate therapy. AV synchrony, by improving the hemodynamic status of the patient (mainly in those with impaired left ventricular function), may demonstrate better survival and comfort of life.

Aged↗

PubMed2000

[Ventricular repolarization and Holter monitoring. Effect of sympathetic blockage on the QT/RR ratio].

Circadian variations of the QT interval and its heart rate dependency have been established. However, the respective roles of the sympathetic and parasympathetic nervous systems in their regulation are still undetermined. Eighteen healthy volunteers (average age 39 +/- 7 years, 10 men) were recruited and selected randomly to receive either placebo or atenolol (100 mg/day). The treatments were crossed after 7 days. The rate dependency of the QT was assessed by day and by night by 24 hour Holter ECG monitoring. The effects of atenolol on the rate dependency of the QT interval depend on the time of day. During the daytime, the QT rate dependency was reduced by atenolol (0.180 (0.162:0.198) versus 0.216 (0.195:0.236) with placebo, p < 0.01) whereas during the night, the QT rate dependency was the same in both groups. Therefore, the betablocker is associated with an inversion of the daily modulation of the QT rate dependency. The daytime rate-dependency of the QT interval in decreased with betablocker therapy. This result suggests a direct or indirect influence of the sympathetic nervous system on the rate dependency of ventricular repolarisation.

Adult↗