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Biomedical subjects

D Bonhorst

Publications and source records attributed to D Bonhorst.

At least 19 recordsLinked to original sources
PubMed2002

Ablation of pulmonary vein foci for the treatment of atrial fibrillation; percutaneous electroanatomical guided approach.

AIMS: To evaluate the usefulness of three-dimensional (3D) electroanatomical mapping of the pulmonary veins (PV) for guiding radiofrequency (RF) ablation of focal atrial fibrillation (AF) in a single session and to correlate the electrophysiological results with the six month clinical outcome. METHODS AND RESULTS: Sixteen consecutive patients with idiopathic paroxysmal AF (more than 1 episode/month) were studied. A non-fluoroscopic mapping system was used to generate 3D electroanatomic maps of the left atrium and deliver RF energy. In patients with frequent ectopies, mapping was performed using the 'hot-cold' approach (looking for the earliest electrogram in the 3D reconstruction). In patients with infrequent/no ectopies, double/ multiple potentials recorded at the PV were tagged. Pacing at these sites to test for inducibility of ectopy or atrial fibrillation was used to define PV foci. The therapeutic endpoint was defined as suppression of premature beats, dissociation of PV potentials and inability to induce AF. Twenty-five foci were identified (multiple foci in 38%). In the 4 pts with frequent ectopies, Group A, these were suppressed by 4 +/- 4.7 applications. In the 12 pts with infrequent/no ectopies, Group B, an average 4.7 +/- 1.8 applications were delivered per focus; the endpoint was achieved in eight of the patients (13 of 21 foci). By 180 days follow-up, 11 patients were free of symptoms and in sinus rhythm, two had paroxysmal AF episodes and 3 have symptomatic ectopies and are receiving antiarrhythmic drugs. The overall success rate at six months was thus 69%, 100% for group A and 58% for group B. CONCLUSION: Electroanatomic guided RF ablation of paroxysmal AF was highly successful in patients with frequent ectopies. The use of electroanatomical mapping for precise anatomical localization of multiple potentials and for guiding the PV ostia isolation allowed successful RF ablation in 50% of pts with infrequent/no ectopies.

Adult↗
PubMed2001

[National registry of non-invasive electrocardiology in 1999].

The Portuguese Association of Arrhythmology. Pacing and Electrophysiology undertook a national registry on resources available in noninvasive laboratories in 1999. Forty-eight hospital centres answered the inquiry. Holter monitoring is an established technique, owned by all cardiology departments in the main hospitals and in 86% of district hospitals. The 40 centres with the technique have a total of 50 analysers and 166 recorders. The number of examinations performed was 14,046 in 1998 and 14,516 in 1999, which shows a remarkable stability. Ninety-three percent of equipments allow ST segment, 38% QT interval and 33% heart rate variability analysis. It is worth nothing the high activity of cardiopneumology technicians in the reading of the exams (94%). Late potential study is less spread. It is only possible in 38% of centers and between 1998 and 1999 the number of exams declined from 592 to 357. Only 12 centers have event recorders, nevertheless the number performed increased from 251 in 1998 to 283 in 1999. Finally, eight centres have tilt test facilities, but we do not have numbers of the examinations that were performed.

Electrocardiography↗
PubMed2001

Implantable cardioverter-defibrillator: beyond efficacy.

OBJECTIVES: The introduction of the implantable cardioverter-defibrillator was a very important advance in the treatment of malignant ventricular arrhythmias. However, its use is associated with some possible adverse events, which should be taken into consideration when a patient is proposed for implantation. These complications may occur early after implantation and be associated with the procedure itself, or they may be late complications, usually associated with the device or the arrhythmia. It was our objective to assess the incidence of these complications in our population of patients. POPULATION AND METHODS: We describe the complications found in 98 patients (55.9 +/- 13.9 years, 89% male) with an implantable cardioverter-defibrillator and compare our results with the incidence of complications described by other authors. RESULTS: We found complications associated with the presence of the implantable cardioverter-defibrillator in 32% of patients. The most frequent complication was inappropriate shocks in 13%. The presence of infection was detected in 4%, lead insulation faults in 5%, need for lead extraction in 2%, repositioning in 1% and re-establishment of the connection with the generator in 2%. In 5% of patients, there was inefficacy of the device, 3% due to non-detected ventricular tachycardias (slow tachycardias) and 2% due to electrical storms. There was syncope in 2% of patients. The total mortality in a 2.9 +/- 1.9 year follow-up was 13% (sudden death in 3%). CONCLUSIONS: Major complications associated with implantable cardioverter-defibrillators were in our experience relatively rare, our results agreeing with those of other centers.

Defibrillators, Implantable↗
PubMed2000

[The patient at risk of sudden death:value of drug therapy].

The evaluation of antiarrhythmic therapy should be based on its effects on total mortality assessed by controlled trials. The author reviews the large trials on antiarrhythmic drugs, during the past ten years, and concludes with the current importance of such therapy. Trials have been conducted in three kinds of high-risk populations: patients with malignant ventricular arrhythmias, survivors of myocardial infarction and patients with congestive heart failure. The results have been disappointing, showing either an increase in mortality with antiarrhythmic drugs (class I, d-sotalol) or a neutral effect (amiodarone). Trials conducted in patients with malignant arrhythmias have shown that the implantable cardioverter-defibrillator was superior to the best available antiarrhythmic therapy. In other high-risk populations, the only drugs that consistently reduced mortality were betablockers, which might have other mechanisms of action besides the antiarrhythmic effect. Amiodarone, the most potent suppressor of ventricular arrhythmias, is indicated in highly symptomatic patients; dl-sotalol is a good alternative to amiodarone. We may conclude from these large trials that study endpoints must be correctly chosen in order to assess the real value of an antiarrhythmic drug. The study population must have a high risk of sudden death and be within an appropriate time window of maximal risk. Antiarrhythmic trials must proceed, learning the lessons from the old studies, trying to test new drugs or new therapeutic strategies, better selecting study populations and new risk markers superior to those currently available.

Adrenergic beta-Antagonists↗
PubMed2000

[Atrial fibrillation: current trends].

The author analyses the current relevance of atrial fibrillation (AF), an arrhythmia no longer viewed as a benign situation, being the first arrhythmic cause of hospitalisation. New data related to the conversion of this arrhythmia to sinus rhythm is reviewed, namely internal atrial defibrillation with low energy shocks and the efficacy of new drugs such as ibutilide. The current role of transesophageal echocardiography in permitting a shorter scheme of anticoagulation before the DC shock is also reviewed. About the importance of maintaining sinus rhythm, the author mentions new data from the Framingham Study showing that AF is an independent predictor of mortality. Attention is drawn to the important role of AF duration before cardioversion, since an "electrical remodeling" does occur, quickly reducing the probability of maintaining sinus rhythm. Concerning the limitations of pharmacological therapy, the author mentions the AFFIRM study that, in a few years, will hopefully solve the controversy concerning the best strategy--maintenance of sinus rhythm versus rate control. Also concerning pharmacological therapy, the author mentions two trials suggestive of the efficacy of amiodarone and dofetilide in AF patients with congestive heart failure. Regarding non-pharmacological options, reference is made to recent advances in surgery of AF and to the search for more simplified operative procedures to reduce intervention risks and duration. To overcome the difficulties in reproducing the maze operation with catheter ablation, new alternatives have appeared, such as energy application inside the pulmonary veins, known as the source of most ectopic atrial beats that trigger AF episodes. The author concludes that since AF is a heterogeneous entity, different therapies must exist, but the pharmacological approach will maintain a central role and non pharmacological therapies should be used as an alternative in refractory cases.

Atrial Fibrillation↗
PubMed2000

[Portuguese Association of Arrhythmology, Pacing and Electrophysiology (APAPE). National Registry of Interventional Electrophysiology for 1999].

Based on data supplied by the centres that execute Interventional Electrophysiology in Portugal, the authors performed a survey of the electrophysiological studies, with or without associated catheter ablation. This report quantifies the experience of all centres, as well as with different classes of ablation techniques. Furthermore, the authors performed a survey of implanted cardiovertor defibrillators, distinguishing their distribution among the different centres. They conclude that the number of centres that practice Interventional Arrhythmias in Portugal is continuously increasing, as well as the number of catheter ablations performed, although these rates have somewhat stabilised in the last year. The number of implanted cardiovertor defibrillators has also grown yearly since 1992, with a 24% increase last year, but is not yet close to the European average of implants per million of inhabitants.

Arrhythmias, Cardiac↗
PubMed1999

Microwave ablation of atrial flutter.

Radiofrequency (RF) ablation of the isthmus between the inferior vena cava and the tricuspid ring has proven to be a safe and successful method of treating atrial flutter (AF). However, RF ablation lesions are small in size requiring a considerable number of energy applications to ablate the AF circuit. The aim of this study was to evaluate the feasibility and efficacy of microwave energy for AF ablation. We report a case of sustained typical AF treated successfully and safely by 1 pulse of microwave (MW) energy. This showed it is possible to treat AF with a small number of pulse applications.

Atrial Flutter↗
PubMed1999

[The Brugada syndrome--a clinical case].

A case report of a patient with syncope and family history of sudden death is presented. The precordial recordings in the standard 12-lead ECG showed a right bundle-branch block pattern with persistent ST elevation in V1 and V2-V3. After a thorough evaluation, we found no underlying organic cardiomyopathy. The diagnosis of symptomatic Brugada syndrome was made. A cardioverter-defibrillator was implanted.

Bundle-Branch Block↗
PubMed1999

[In recurrent atrial fibrillation should a sinus rhythm always try to be maintained? No. What are the therapeutic alternatives?].

Despite the high incidence of atrial fibrillation, and the morbidity and mortality associated with this arrhythmia, we are still not sure of the best strategy to deal with it. There is little comparative data between the two strategies most often used: cardioversion and prophylactic antiarrhythmics to maintain sinus rhythm; or pharmacological control of ventricular rate and antithrombotic drugs. The first strategy seems to be the most desirable, but there are two arguments against its use in all patients: 1. It is not indicated when the probability of maintaining sinus rhythm during a sufficiently long period of time is poor. This is case of premature recurrence despite several long course atrial fibrillation treatments (more than one year), and the presence of a very large left atrium. 2. It is not indicated when the advantages of maintaining sinus rhythm do not outweigh its pitfalls. These are mainly related to the use of antiarrhythmic drugs, the efficacy of which is not very great and may present a potential risk of lethal pro-arrhythmia or severe collateral effects. The alternative strategy is feasible with the use of less toxic drugs and the high efficacy and safety of anticoagulant therapy for the prevention of thromboembolic events is currently known. Therefore, we are able to achieve a reasonable control of patient symptoms with a low risk of serious incidents. Trials comparing these strategies have not yet been concluded, therefore therapy must be individualised and based on a correct evaluation of foreseeable risks and benefits.

Anti-Arrhythmia Agents↗
PubMed1998

[Role of auxiliary diagnostic tests in the clarification of the etiology of syncope: experience at an arrhythmia center].

UNLABELLED: Syncope is a syndrome caused by a reversible reduction of blood to the brain. Three hemodynamic abnormalities can cause syncope: an acute decrease in cardiac output, an acute increase in cerebrovascular resistance and a fall in systemic blood pressure due to ineffective control of peripheral vascular resistance. We made a retrospective study of 121 patients with syncope history, 67 males, and 57 females, with mean age 48 +/- 14 years, and at least six months of clinical follow-up. Twelve patients had valvular disease, two patients had hypertrophic cardiomyopathy, eight patients had dilated cardiomyopathy, 14 patients had ischemic disease, three patients had congenital disease; 82 patients did not have cardiac disease. Syncope etiology was arrhythmic in 69 patients: 47 patients had tachyarrhythmia (supraventricular--in 27 patients and ventricular in 20 patients) and 15 patients had bradyarrhythmia (seven patients had sinus node disease and eight patients had atrioventricular block). Non arrhythmic etiology of syncope was identified in 29 patients (neurologic disease--ten patients, metabolic disease--one patient and iatrogenic--two patients; vasodepressor syncope--14 patients, and hypertrophic cardiomyopathy--two patients). It was not possible to determine the syncope etiology in 30 patients. The assessment of patients who present syncope depends on establishing the basis for the symptoms. The initial step is differentiating patients with normal cardiovascular systems from those with heart disease. In the former, tilt-table testing proved to be the most productive from a diagnostic perspective; in the latter group, electrophysiologic evaluation was the most elucidative from a diagnostic perspective. The ultimate goal is to obtain a sufficiently strong correlation between syncopal symptoms and detected abnormalities to permit an accurate assessment of prognosis and to develop an effective treatment plan. CONCLUSIONS: It is very important to establish the etiology of syncope for optimal management of patients and it is therefore possible to control the symptoms in the majority of them. The patients who present syncope require a complete history and a physical examination for an appropriate workup to be initiated. Tilt-table testing was the most accurate for the diagnosis of vasodepressor syncope while electrophysiologic testing provides an accurate method for assessing the etiology of tachyarrhythmic syncope.

Adult↗
PubMed1998

[Syncope in a patient with Ebstein's anomaly and Wolff-Parkinson-White syndrome].

We describe a clinical case of a patient with Ebstein's anomaly and syncope in Wolff-Parkinson-White's syndrome. After a radiofrequency ablation of an accessory atrioventricular pathway there was a different arrhythmia of ventricular origin. Although we have some doubts about their clinical relevance, we discuss the complex arrhythmic background, the medical management difficulties and the prognostic issues. There is an evaluation about ablation usefulness in this context regarding future attitudes in relation to other kinds of rhythm disorder.

Ebstein Anomaly↗
PubMed1997

[The prognostic significance of late potentials in patients with chronic coronary disease].

OBJECTIVE: The prognostic value of late potentials (LP) in the subacute phase of myocardial infarction (MI) is well known, but its prognostic value in long-standing coronary disease (LSCD) has not yet been established. In a population with LSCD we searched for a relation between the presence of LP in signal-averaged ECG (SAECG) performed before cardiac catheterization, and the incidence of cardiac events. METHODS: Based on our department's casuistics, we selected 50 consecutive patients with coronary disease confirmed by an angiogram and LP, and a control group without LP, in SAECG. We selected 91 men and nine women with an average age of 59 +/- 8 years. None of the patients had had ischemic events or revascularization procedures, in the 3 month period before catheterization. The follow-up was made between the time of the SAECG and the last medical visit. The events recorded were: ventricular arrhythmia, cardiac death, coronary angioplasty, coronary artery by-pass graft, MI or unstable angina. RESULTS: During a follow-up period of 20.1 +/- 8 months, we found no statistically significant difference between the two groups, regarding the incidence of such events. However, there was a higher incidence of ventricular arrhythmic events in the group with LP (four patients with ventricular tachycardia against none in the control group). All patients with ventricular tachycardia had had a previous MI. CONCLUSIONS: In this study, the presence of LP in SAECG did not have the same prognostic value found in the subacute phase of MI, but a higher incidence of arrhythmic events was observed in the group with LP and a previous MI.

Adult↗
PubMed1997

[Catheter ablation with radiofrequency energy in 100 patients with Wolff-Parkinson-White syndrome].

OBJECTIVE: The aim of this paper was to evaluate our results of radiofrequency catheter ablation (RFCA) of accessory pathways in patients with WPW syndrome. STUDY PATIENTS: We studied 100 consecutive patients with WPW syndrome, 52 men and 48 women, mean age 37 +/- 15 years who underwent RFCA. All patients were symptomatic, with documented episodes of supraventricular tachycardia and 9% of patients had underlying cardiac disease. METHODS: The RFCA was performed without antiarrhythmic drugs in the same session of the electrophysiologic diagnosis. The location of the accessory pathway site was obtained by catheter mapping, based on the premature and/or the presence of Kent potentials. According to the location of the accessory pathway, the ablation catheter was introduced either by the femoral vein or artery with mapping of the tricuspid or mitral ring. In the first cases performed energy application was manually controlled and thereafter was temperature guided with an upper temperature limit of 70 degrees C. We considered primary success criteria the disappearance of the delta wave in the surface ECG and the absence of ventricular preexcitation under atrial pacing and after adenosine injection. Clinical success was defined as the absence of clinical recurrence of tachycardia during the follow-up period. RESULTS: The primary success rate achieved was 88%; 91% in the left free wall pathways, 100% in the right free wall and 85% in the septal pathways (antero-septal-83%; right postero-septal-76.5%; left postero-septal-92%). A second ablation procedure was performed in seven of the twelve patients with primary unsuccess obtaining a final success rate of 93% (left free wall-94.5%; septal pathways-91.6%). After a mean follow-up period of 8 +/- 7 months clinical recurrence occurred in 9% (eight patients), five of which are under anti-arrhythmic therapy (62.5%). Clinical success rate at the end of the follow-up period was 88%. CONCLUSIONS: In our experience RFCA has shown to be safe and with a high success rate in patients with symptomatic pre-excitation. In this group of patients it was an effective therapy.

Adolescent↗