Biomedical subjects

C Timmermans

Publications and source records attributed to C Timmermans.

At least 19 recordsLinked to original sources

PubMed2005

Radiofrequency ablation of atrial arrhythmias after previous open-heart surgery.

AIM: To report the results of ablation of atrial arrhythmias (AA) after previous open-heart surgery. METHODS: Nineteen patients [50+/-11 years, 11 women] underwent ablation of symptomatic AAs after previous open-heart surgery. In 11 patients mapping was performed using conventional multielectrode catheters. In the other eight patients CARTO electro-anatomical mapping system was used to supplement conventional mapping. RESULTS: After conventional mapping, 10/11 patients (91%) were found to have typical atrial flutter (AFL). The cavotricuspid isthmus was successfully ablated in these 10 patients. CARTO combined with conventional mapping showed that 7 of 8 patients had one macro-reentry right atrial circuit. The remaining patient had two focal atrial tachycardias. CARTO-guided ablation was successful in all eight patients (100%). After follow-up of 12+/-11 months, 2/18 patients (11%) had recurrence of either the same (n=1) or a new (n=1) AA. CONCLUSIONS: AAs after previous open-heart surgery can be ablated successfully (>90%) with a low recurrence rate (11%) at 1-year follow-up. Typical AFL was found frequently (14/19 patients, 72%). This could be ablated successfully, often, after conventional mapping alone. CARTO helps to uncover peri-scar reentry and guide the ablation by creating a line of block connecting the scar to another landmark (unconventional isthmus).

Atrial Flutter↗

PubMed2004

Transvenous cryoablation of cardiac arrhythmias.

This study reports on the acute and long-term results of cryoablation in patients with supraventricular and ventricular tachycardia. One hundred fifty nine patients with cardiac arrhythmias (147 with supraventricular and 12 with ventricular tachycardia) were consecutively enrolled in our institution to undergo trnasvenous cryoablation with a new cryotechnology system (CryoCor trade mark ). This cryoablation system consists of a console, an articulating arm housing a pre-cooler, and a disposable sterile steerable bipolar 10-fr catheter. The N(2)O is used as a main refrigerant. The acute and chronic outcomes (after 15 months for patients with supraventricular tachycardia and 9 months for patients with ventricular tachycardia) were comparable to those using radiofrequency energy. From this study we concluded that transvenous cryoablation is a safe and effective therapy for the treatment of cardiac arrhythmias.

Adult↗

PubMed2001

Biatrial activation in isthmus-dependent atrial flutter.

BACKGROUND: The aim of this study was to determine the biatrial activation pattern in isthmus-dependent atrial flutter (AFL) to understand the functional interatrial connections and the activation pattern of the left atrium (LA). METHODS AND RESULTS: Biatrial activation was performed, using an electroanatomic mapping system, in 10 patients undergoing right atrial isthmus ablation for counterclockwise (n=7) or clockwise (n=3) AFL. The AFL circuit was peritricuspid and propagated slowly (0.5+/-0.2 m/s) through the isthmus. LA was activated by two wave fronts, with discrete breakthroughs in the superior, mid, or inferior atrial septum. The activation of LA overlapped 50+/-16% of the AFL cycle length. In counterclockwise AFL, at least one breakthrough was located in the inferior atrial septum. LA activation began immediately after the exit of the flutter wave from the isthmus and was directed inferosuperiorly in all patients, being synchronous with the atrial septal activation. The septal breakthroughs in patients with clockwise AFL were variably located. The direction of LA activation was superoinferior in 2 and inferosuperior in 1 patient. CONCLUSIONS: The circuit of isthmus-dependent AFL was entirely in the right atrium. LA activation was a bystander and followed trans-septal conduction across the inferior coronary sinus-LA connection, Bachmann's bundle, and/or fossa ovalis.

Atrial Flutter↗

PubMed2001

Precise measurement of the positive muon anomalous magnetic moment.

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

Journal Article↗

PubMed2001

Use of a saline-irrigated tip catheter for ablation of ventricular tachycardia resistant to conventional radiofrequency ablation: early experience.

INTRODUCTION: Radiofrequency (RF) catheter ablation of ventricular tachycardia (VT) may fail if the critical isthmus is located intramyocardially or epicardially. The design of a saline-irrigated tip (SIT) catheter (Thermo-Cool, Cordis-Webster) involves active cooling of the tip electrode, which allows creation of larger ablation lesions. METHODS AND RESULTS: Eight patients (6 men, age 59 +/- 12 years) in whom the clinical target VT (cycle length 430 +/- 97 msec) could not be ablated using a conventional 4-mm tip RF ablation catheter underwent additional attempts to ablate this VT using a SIT catheter. Six patients had an old myocardial infarction, 1 patient had a dilated cardiomyopathy, and 1 patient had a structurally normal heart. Ablation of the clinical target VT using a SIT catheter was attempted from the left ventricle in 6 (septal, posterobasal, and inferior: 2 each) and from the right ventricle in 2 patients (both septal), by entrainment (n = 6), activation (n = 1), or pace mapping (n = 1). A mean of 6 +/- 5 (range 2 to 15) pulses were delivered. Target VT ablation was successful in 5 patients (63%). After successful ablation, at a mean follow-up of 6.5 +/- 4 months and while taking antiarrhythmic drugs, all 5 patients were free of VT recurrences. CONCLUSION: The clinical target VT could be ablated using a SIT catheter in 5 (63%) of the 8 patients in whom ablation using a conventional RF catheter was unsuccessful. In the 2 patients with septal VT, a biventricular approach to mapping and ablation was required.

Adult↗

PubMed2001

Class IC antiarrhythmic drug induced atrial flutter: electrocardiographic and electrophysiological findings and their importance for long term outcome after right atrial isthmus ablation.

OBJECTIVE: To describe the electrocardiographic and electrophysiological findings of new atrial flutter developing in patients taking class IC antiarrhythmic drugs for recurrent atrial fibrillation, and to report the long term results of right atrial isthmus ablation in relation to the ECG pattern of spontaneous atrial flutter. DESIGN: Retrospective analysis. SETTING: Tertiary care academic hospital. PATIENTS: 24 consecutive patients with atrial fibrillation (age 54 (12) years; 5 female, 19 male) developing atrial flutter while taking propafenone (n = 12) or flecainide (n = 12). RESULTS: The ECG was classified as typical (n = 13; 54%) or atypical atrial flutter (n = 8) or coarse atrial fibrillation (n = 3). Counterclockwise atrial flutter was the predominant arrhythmia. Acute success after isthmus ablation was similar in patients with typical (12/13) and atypical (8/8) atrial flutter. After long term follow up (13 (6) months, range 6-26 months), continuation of antiarrhythmic drug treatment appeared to result in better control of recurrences of atrial fibrillation in patients with typical atrial flutter (11/13) than in those with atypical atrial flutter (4/8), but the difference was not significant. Ablation for coarse atrial fibrillation was unsuccessful. CONCLUSIONS: New atrial flutter developing in patients taking class IC antiarrhythmic drugs for recurrent atrial fibrillation has either typical or atypical flutter wave morphology on ECG. The endocardial activation pattern and the acute results of ablation suggest that the flutter circuit was located in the right atrium and that the isthmus was involved in the re-entry mechanism. There appeared to be better long term control of recurrent atrial fibrillation in patients with typical (85%) as compared with atypical atrial flutter (50%). Patients developing coarse atrial fibrillation may not be candidates for this strategy.

Adult↗

PubMed2001

The effect of incentive spirometry on postoperative pulmonary complications: a systematic review.

OBJECTIVE: To systematically review the evidence examining the use of incentive spirometry (IS) for the prevention of postoperative pulmonary complications (PPCs). METHODS: We searched MEDLINE, CINAHL, HealthSTAR, and Current Contents databases from their inception until June 2000. Key terms included "incentive spirometry," "breathing exercises," "chest physical therapy," and "pulmonary complications." Articles were limited to human studies in English. A secondary search of the reference lists of all identified articles also was conducted. A critical appraisal form was developed to extract and assess information. Each study was reviewed independently by one of three pairs of group members. The pair then met to reach consensus before presenting the report to the entire review group for final agreement. RESULTS: The search yielded 85 articles. Studies dealing with the use of IS for preventing PPCs (n = 46) were accepted for systematic review. In 35 of these studies, we were unable to accept the stated conclusions due to flaws in methodology. Critical appraisal of the 11 remaining studies indicated 10 studies in which there was no positive short-term effect or treatment effect of IS following cardiac or abdominal surgery. The only supportive study reported that IS, deep breathing, and intermittent positive-pressure breathing were equally more effective than no treatment in preventing PPCs following abdominal surgery. CONCLUSIONS: Presently, the evidence does not support the use of IS for decreasing the incidence of PPCs following cardiac or upper abdominal surgery.

Abdomen↗

PubMed2000

Initial clinical experience with ambulatory use of an implantable atrial defibrillator for conversion of atrial fibrillation. Metrix Investigators.

BACKGROUND: A recent study has shown that the implantable atrial defibrillator can restore sinus rhythm in patients with recurrent atrial fibrillation when therapy was delivered under physician observation. The objective of this study was to evaluate the safety and efficacy of ambulatory use of the implantable atrial defibrillator. METHODS AND RESULTS: An atrial defibrillator was implanted in 105 patients (75 men; mean age, 59+/-12 years) with recurrent, symptomatic, drug-refractory atrial fibrillation. After successful 3-month testing, patients could transition to ambulatory delivery of shock therapy. Patients completed questionnaires regarding shock therapy discomfort and therapy satisfaction using a 10-point visual-analog scale (1 represented "not at all," 10 represented "extremely") after each treated episode of atrial fibrillation. During a mean follow-up of 11.7 months, 48 of 105 patients satisfied criteria for transition and received therapy for 275 episodes of atrial fibrillation. Overall shock therapy efficacy was 90% with 1.6+/-1.2 shocks delivered per episode (median, 1). Patients rated shock discomfort as 5.2+/-2.4 for successful therapy and 4.2+/-2.2 for unsuccessful therapy (P:>0.05). The satisfaction score was higher for successful versus unsuccessful therapy (3.4+/-3. 3 versus 8.7+/-1.3, P:<0.05). There was no ventricular proarrhythmia observed throughout the course of this study. CONCLUSIONS: Ambulatory use of an implantable atrial defibrillator can safely and successfully convert most episodes of atrial fibrillation, often requiring only a single shock. Successful therapy is associated with high satisfaction and only moderate discomfort.

Adult↗

PubMed2000

Comparison of results of an 8-mm split-tip versus a 4-mm tip ablation catheter to perform radiofrequency ablation of type I atrial flutter.

Thirty consecutive patients with type I atrial flutter were randomized to undergo radiofrequency ablation using an 8-mm split-tip versus a 4-mm tip catheter. Procedural success was high in both groups (100% vs 93%). However, requirement of a fewer number of radiofrequency pulses and fluoroscopy time suggests superiority of the 8-mm split-tip over the 4-mm tip ablation catheter.

Atrial Flutter↗

PubMed2000

Spontaneous episodes of atrial fibrillation after implantation of the Metrix Atrioverter: observations on treated and nontreated episodes. Metrix Investigators.

OBJECTIVES: We sought to evaluate the number and duration of device-treated and self-terminating, nontreated episodes of atrial fibrillation (AF) after implantation of the Metrix Atrioverter. BACKGROUND: A recent study has shown that the Atrioverter can rapidly restore sinus rhythm in patients with AF; however, the effect of the device on the clinical course of the arrhythmia in these patients is unknown. METHODS: The Atrioverter was implanted in 51 patients with symptomatic, recurrent, drug-refractory AF. The device was programmed to periodically monitor the cardiac rhythm. Defibrillation of AF episodes was performed under physician observation. RESULTS: During a mean follow-up of 260 +/- 144 days, 1,161 episodes of AF were observed during valid monitoring periods in 45 of 51 patients. Forty-one patients experienced 231 episodes for which they sought defibrillation therapy. The average duration of the treated episodes during valid monitoring periods (190 of 231 episodes in 39 of 41 patients) was significantly longer than that of the nontreated episodes (38 +/- 44 vs. 10 +/- 8 h; p < 0.05). The time between episodes requiring Atrioverter therapy increased, and the risk of having an episode requiring treatment decreased. No changes were observed in the number and duration of the short-lasting, nontreated episodes as time since implantation of the device increased. CONCLUSIONS: In patients with symptomatic, recurrent, drug-refractory AF, the frequency of long-lasting episodes, which were treated under observation with repeated defibrillation using the Atrioverter, decreased. The number and duration of short-lasting, nontreated episodes did not change during the 20-month study period. The effect of ambulatory use of the device on the recurrence of short-lasting episodes needs to be evaluated.

Adult↗

PubMed2000

Design and preliminary data of the Metrix Atrioverter expanded indication trial.

The Metrixtrade mark Atrioverter Expanded Indication Trial evaluates the safety and efficacy of an implantable atrial defibrillator in patients with symptomatic, recurrent and drug refractory atrial fibrillation who also have structural heart disease. In this ongoing multicenter study, all patients are anticoagulated and concomitant antiarrhythmic drug treatment is left to the preference of the physician. Holter monitoring is performed prior to enrollment in the study. Spontaneous episodes of atrial fibrillation (AF) are treated under physician observation and when patients are ambulatory, the device is programmed in a monitoring mode. The atrial defibrillation threshold is measured at implantation and at 3, 6 and 12 months thereafter. The performance of the AF detection and R-wave synchronization algorithm is assessed at implantation, at regular follow-up intervals, and each time the patient visits the hospital for treatment of a spontaneous episode of AF. An echocardiogram is performed prior to implantation, at 3 and 6 month follow-up and for patients with an implanted heart valve, after 20 and 50 atrial defibrillation shocks have been delivered. The study started on October 1997 and will end after the last patient enrolled completes his/her six-month post-implantation follow-up, unless a safety issue arises. As of September 1998, 6 patients (2 patients with tachycardia induced cardiomyopathy, 1 patient with a mitral valve prosthesis, 2 patients with hypertrophic cardiomyopathy and 1 patient with congenital heart disease) have been enrolled in the study. Over 350 shocks have been delivered for atrial defibrillation testing or termination of spontaneous AF episodes. There have been no reported cases of ventricular proarrhythmia or inaccurately synchronized shocks and no complications of device therapy in this population.

Adolescent↗

PubMed2000

Decreasing the number of leads required for an implantable atrial defibrillator: use of a new 2-lead system.

BACKGROUND: The purpose of this study was to evaluate the use of a new 2-lead system for detection of atrial fibrillation (AF) and atrial defibrillation. METHODS: In 16 patients undergoing elective cardioversion of AF, a 2-lead system was compared with the conventional 3-lead system in a randomized trial. The new 2-lead system consisted of a catheter with a distal bipolar right ventricular electrode pair and a proximal right atrial shock electrode coil and a separate decapolar defibrillation catheter in the coronary sinus. For the 3-lead system, an additional decapolar catheter was placed in the right atrium. AF and sinus rhythm signal amplitude detection and atrial defibrillation threshold (ADFT) were compared in each patient with both systems. RESULTS: Successful defibrillation was obtained in all patients. ADFT for the 2-lead system was significantly higher compared with the 3-lead system (370 +/- 112 vs 316 +/- 100 V, P < .05; 9.3 +/- 5.2 vs 6.8 +/- 4.2 J, P < .05). In contrast, there was an increase in impedance for the 3-lead system (77 +/- 16 ohms vs 68 +/- 13 ohms; P < .05). AF had a lower signal amplitude compared with sinus rhythm for both systems (P < .05), and the 2-lead system had a lower signal amplitude compared with the 3-lead system for both rhythms (P < .05). CONCLUSION: The use of a 2-lead system with this configuration is not superior to the 3-lead system regarding AF signal amplitude detection and ADFT. Further study is needed with implantable-quality leads in place of the temporary catheters used in this study.

Adult↗

PubMed2000

Management of atrial arrhythmias secondary to severe congenital heart disease with the Atrioverter.

An atrial defibrillator was implanted in a patient with congenitally corrected transposition of the great arteries, associated cardiac abnormalities, and persistent atrial arrhythmias. During a 15-month follow-up, 14 of 20 spontaneous episodes of his arrhythmias were successfully treated with the device. Two of these episodes were converted to sinus rhythm during ambulatory use of the device. Successful use of the device required implantation of a third defibrillation lead in the persistent left-sided superior caval vein and rigid control of congestive heart failure. An atrial defibrillator may be a valid treatment option in patients with congenital heart disease crippled by atrial fibrillation.

Adult↗

PubMed2000

Capture and fusion beats during atrial fibrillation and ventricular tachycardia.

Two patients were presented, and two previously unreported observations were made. Patient 1, a 50 year old man with episodic palpitations and dizziness for 10 years, exhibited initiation of idiopathic ventricular tachycardia (VT) by atrial fibrillation (AF). Patient 2, a 43 year old woman with a structurally normal heart but recurrent palpitations for one year, demonstrated fusion and capture beats during simultaneous VT and AF. An explanation is given as to why the latter phenomenon is rarely observed.

Adult↗

PubMed1999

Use of sedation during cardioversion with the implantable atrial defibrillator.

BACKGROUND: The low shock energy used during internal atrial defibrillation may decrease the need for sedation during defibrillation with an implantable atrial defibrillator. METHODS AND RESULTS: The atrial defibrillator (Metrix Atrioverter) was implanted in 12 patients. During the in-hospital treatment of atrial fibrillation (AF) episodes, intravenous sedation was given only on patient request. The Atrioverter was programmed for ambulatory therapy in 4 patients. Efficacy, number of shocks delivered, and sedation requirements were recorded. A total of 393 shocks (1.8+/-1. 6 shocks/AF episode) were delivered to treat 213 AF episodes; 85 of 213 AF episodes (40%) were treated away from the hospital. Sinus rhythm was restored in 195 AF episodes (92%). Five patients never requested sedation. No sedation was needed for ambulatory-treated AF episodes. During the treatment of 26 of 213 AF episodes (12%), 75 shocks were delivered after patients received sedation. The number of shocks required to treat an AF episode determined the need for sedation (4.3+/-2.1 shocks for AF episodes requiring sedation versus 2+/-1 shocks for AF episodes requiring no sedation; P<0.001). These additional shocks were needed to treat immediate reinitiation of AF (14 episodes) or initial failure to cardiovert (4 episodes). For 8 AF episodes, sedation was requested before the first shock. CONCLUSIONS: This study suggests that, in a selected group of patients, AF can be treated with Atrioverter therapy without sedation. Successful ambulatory treatment of AF episodes with the Atrioverter, programmed to deliver </=2 shocks, did not require sedation. When multiple shocks were required to treat an AF episode, the need for sedation increased and included patients initially not requesting sedation.

Aged↗

PubMed1999

Are electrophysiological changes induced by longer lasting atrial fibrillation reversible? :observations using the atrial defibrillator.

BACKGROUND: Studies in animal hearts have shown shortening of the atrial effective refractory period (AERP) and loss of the relation between the AERP and heart rate after prolonged periods of atrial fibrillation (AF). The purposes of this study were (1) to evaluate atrial electrophysiology after a long period of sinus rhythm in patients who had longer lasting recurrent AF that was successfully treated with the Metrix Atrioverter and (2) to analyze the effect of prompt cardioversion on subsequent AF episodes and the duration of sinus rhythm. METHODS AND RESULTS: Four patients with recurrent AF (duration, 3 to 21 years; mean+/-SD, 13+/-7.6 years) were studied after the implantation of an Atrioverter. The Atrioverter stores and analyzes 3 minutes of cardiac rhythm every hour. Before implantation, AERP was measured. During a mean follow-up of 14 months, 52 spontaneous (39 treated and 18 nontreated) AF episodes occurred while the patients were on antiarrhythmic drugs. All patients were electrophysiologically studied after they had been in sinus rhythm for at least 1000 hours (range, 1052 to 2675 hours). Before Atrioverter implantation, AF was induced by 1 atrial premature beat in 3 patients and not induced in the remaining patient. After a long period in sinus rhythm (>1000 hours), AF could be induced in the same 3 patients in the same way as before implantation. In the patient in whom no AF was induced, right AERP values measured using the single extrastimulus technique at 3 pacing cycle lengths (600, 500, and 430 ms) were similar to those before implantation. CONCLUSIONS: AF was still inducible by a single atrial premature beat after long episodes of sinus rhythm in 3 of 4 patients with previously longer lasting AF. In the patient in whom no AF was induced, AERP behaved like it did before implantation. In these patients with longer lasting recurrent AF, no return to "normal" atrial electrophysiology could be demonstrated.

Aged↗

PubMed1999

Isoproterenol to evaluate resumption of conduction after right atrial isthmus ablation in type I atrial flutter.

BACKGROUND: After radiofrequency (RF) ablation of atrial flutter (AFL), the demonstration of bidirectional isthmus conduction (BIC) block is considered the hallmark of a successful procedure. The purpose of our study was to test the persistence of BIC block after isoproterenol administration and to evaluate the importance of this finding with regard to AFL recurrences. METHODS AND RESULTS: RF ablation of AFL was performed in 44 consecutive patients with type I AFL by linear ablation of the posterior isthmus (n=29 patients), septal isthmus (n=4 patients), or both right atrial (RA) isthmi (n=11 patients). The procedural end point was complete BIC block and noninducibility of AFL. In case of noninducibility and apparent BIC block, the pacing protocol was repeated under isoproterenol infusion (1 to 3 microgram/min). Reversal of apparent BIC block occurred in 7 (15.9%) of 44 patients. Six patients had bidirectional and 1 had unidirectional resumption of isthmus conduction. Counterclockwise AFL could be reinduced in 4 of these patients. Two to 24 (median, 4) additional RF applications were required to achieve permanent BIC block. At a mean follow-up of 7.3+/-7.6 months (range, 2 to 31 months), 2 (4.5%) of 44 patients had AFL recurrences. CONCLUSIONS: Partial linear RF ablation could possibly aggravate preexisting nonuniform anisotropic conduction in the RA isthmus, resulting in profound conduction slowing and apparent BIC block. Isoproterenol can unmask apparent BIC block, thus providing an opportunity to assess the possibility of reversal of BIC block and completeness of isthmus ablation during the same procedure. The low incidence (4.5%) of AFL recurrences at follow-up suggests that noninducibility and BIC block under isoproterenol infusion may be a better end point for successful AFL ablation.

Adult↗

PubMed1999

Effect of butorphanol tartrate on shock-related discomfort during internal atrial defibrillation.

BACKGROUND: In patients with atrial fibrillation, intracardiac atrial defibrillation causes discomfort. An easily applicable, short-acting analgesic and anxiolytic drug would increase acceptability of this new treatment mode. METHODS AND RESULTS: In a double-blind, placebo-controlled manner, the effect of intranasal butorphanol, an opioid, was evaluated in 47 patients with the use of a step-up internal atrial defibrillation protocol (stage I). On request, additional butorphanol was administered and the step-up protocol continued (stage II). Thereafter, if necessary, patients were intravenously sedated (stage III). After each shock, the McGill Pain Questionnaire was used to obtain a sensory (S), affective (A), evaluative (E), and total (T) pain rating index (PRI) and a visual analogue scale analyzing pain (VAS-P) and fear (VAS-F). For every patient, the slope of each pain or fear parameter against the shock number was calculated and individual slopes were averaged for the placebo and butorphanol group. All patients were cardioverted at a mean threshold of 4.4+/-3.3 J. Comparing both patient groups for stage II, the mean slopes for PRI-T (P=0.0099), PRI-S (P=0.019), and PRI-E (P=0.015) became significantly lower in the butorphanol group than in the placebo group. Comparing patients who received the same shock intensity ending stage I and going to stage II, in those patients randomized to placebo the mean VAS-P (P=0.023), PRI-T (P=0. 029), PRI-S (P=0.030), and PRI-E (P=0.023) became significantly lower after butorphanol administration. CONCLUSIONS: During a step-up internal atrial defibrillation protocol, intranasal butorphanol decreased or stabilized the value of several pain variables and did not affect fear. Of the 3 qualitative components of pain, only the affective component was not influenced by butorphanol. The PRI evaluated pain more accurately than the VAS.

Administration, Intranasal↗