Usefulness of remote magnetic navigation for ablation of ventricular arrhythmias originating from outflow regions.

Monomorphic ventricular tachycardia (VT) and symptomatic monomorphic PVCs originating from the region of the right and left outflow tracts are increasingly treated by radiofrequency (RF) catheter ablation. Technical difficulties in catheter manipulation to access these outflow tract areas, very accurate mapping and reliable catheter stability are key issues for a successful treatment in this vulnerable region. VT ablation from the aortic sinus cusp (ASC) in particular carries a significant risk of perforation, of creating left coronary artery injury and of damage to the aorta and the aortic valve.This case series describes RF ablation of VT originating in the outflow region using the remote magnetic navigation system (MNS). Potential advantages of the MNS are catheter flexibility, steering accuracy and reproducibility to navigate to a desired location with a low probability of perforating the myocardium. This report supports the idea of using advanced MNS technology during RF ablation in regions which are difficult to reach and thin walled, such as parts of the outflow tract and the ASC. (Neth Heart J 2009;17:245-9.).

Transvenous radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia and its pitfalls: a rationale for cryoablation?

Today, radiofrequency (RF) catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is accompanied by a high success, a low recurrence, and a low complication rate. Despite the fact that over the years this technique has been refined, several shortcomings still remain. In this overview, the most important pitfalls in the treatment of AVNRT with RF energy are discussed. Cryotherapy has the ability to overcome some of them. Both ice mapping and cryo-adherence are important characteristics of this energy source to study prospective ablation sites before a definitive and irreversible lesion is created. Theoretically, this could lead to less applications with less tissue damage and abolish the risk for permanent conduction disturbances. The early experience with this technique will be described. Until now, it still has to be proven that in a large cohort of patients, cryotherapy is at least as effective, and safer than RF.

Magnetic assisted navigation in electrophysiology and cardiac resynchronisation: a review.

Magnetic assisted navigation is a new innovation that may prove useful in catheter ablation of cardiac arrhythmias and cardiac resynchronization therapy. The ability to steer extremely floppy catheters and guidewires may allow for these to be positioned safely in previously inaccessible areas of the heart. The integration of other new technology, such as image integration and electroanatomic mapping systems, should advance our abilities further. Although studies have shown the technology to be feasible, with the advantage to the physician of decreased radiation exposure, studies need to be performed to show additional benefit over standard techniques.

Multicenter low energy transvenous atrial defibrillation (XAD) trial results in different subsets of atrial fibrillation.

OBJECTIVES: This prospective, multicenter trial was aimed at defining efficacy and safety of low energy shocks during atrial fibrillation in a diverse cohort of patients. BACKGROUND: Experimental studies in sheep and preliminary data in humans have suggested that low energy internal shocks delivered between right atrial and coronary sinus electrode catheters may terminate atrial fibrillation. METHODS: Biphasic 3/3-ms R wave synchronous shocks were delivered between two electrode catheters in the right atrium and coronary sinus. The defibrillation protocol started with a test shock of 20 V, and shocks increased in 40-V steps until restoration of sinus rhythm or a maximum of 400 V. Shock delivery was withheld after short RR intervals. In 141 patients with atrial fibrillation, the protocol was carried out under sedation in case the shock was associated with discomfort. The atrial arrhythmia was paroxysmal (< or = 7 days) in 50 patients, chronic (> 30 days) in 53, intermediate (> 7 days, < or = 30 days) in 18 and induced in 20. Underlying heart disease was present in 88 patients (62%). RESULTS: Paroxysmal atrial fibrillation was successfully terminated in 46 (92%) of 50 patients, chronic atrial fibrillation in 37 (70%) of 53, intermediate in 16 (89%) of 18 and induced in 16 (80%) of 20. Mean conversion threshold was 1.8 J (213 V) in the induced group, 2.0 J (229 V) in the paroxysmal group, 2.8 J (272 V) in the intermediate group and 3.6 J (311 V) in the chronic group. The conversion voltage was significantly (p < 0.001) higher in the chronic group than in the other groups of atrial fibrillation and increased significantly with the duration of atrial fibrillation and with left atrial size (p < 0.05). Of 1,779 R wave synchronized shocks delivered with a mean (+/-SD) preceding RR interval of 676 +/- 149 ms, no ventricular arrhythmia was induced. The latter may occur after unsynchronized shocks. CONCLUSIONS: Low energy transvenous shocks in patients with atrial fibrillation are effective and safe, provided that shocks are properly synchronized to R waves with preceding RR intervals that meet appropriate cycle length criteria. This study provides data that may be useful in the development of an implanted atrial defibrillator.

Pulmonary vein antrum isolation guided by phased-array intracardiac echocardiography: A third way to do PV ablation.

BACKGROUND: Pulmonary vein isolation (PVI) has emerged as an important strategy in the treatment of patients with atrial fibrillation (AF). The two most frequently used techniques are segmental PVI and left atrial circumferential ablation. AIM: To describe and discuss pulmonary vein antrum isolation guided by phased-array intracardiac echocardiography (ICE) as an alternative approach, and to present initial results. METHODS: Patients with symptomatic AF were included. The antra (the larger circumferential area around the PVs) were isolated guided by ICE. ICE was also used to titrate the ablation energy. RESULTS: 38 patients (3 with persistent AF) were included. Of the 35 patients with paroxysmal AF, 24 are without recurrences, and in six the incidence of paroxysms was significantly reduced after one procedure and a mean follow-up of 201 days. No major complications occurred. CONCLUSION: Pulmonary vein antrum isolation guided by ICE is a promising technique in AF ablation and has the potential to avoid severe complications.

Long-term prognostic value of dobutamine stress echocardiography in patients with atrial fibrillation.

STUDY OBJECTIVE: To assess the long-term prognostic value of dobutamine stress echocardiography (DSE) for cardiac events (cardiac death, myocardial infarction, and late revascularization) in patients with atrial fibrillation (AF). METHODS: Baseline ECGs were studied in patients undergoing DSE between 1989 and 1998. Sixty-nine patients had AF before DSE. Prognostic value of DSE in these patients was compared with a control group who had sinus rhythm (n = 1,664). The presence of stress-induced ischemia was noted for every patient. The mean follow-up period was 35 months (range, 6 to 84 months). Data are presented as hazards ratio (HR) with 95% confidence interval (CI). RESULTS: Heart rate at rest was higher in patients with AF (77 +/- 15 beats/min vs 73 +/- 14 beats/min; p = 0.04); however, double product at peak stress was not different between patients with AF and sinus rhythm (17,602 vs 17,169, respectively; p = 0.46). In patients with AF, target heart rate was achieved at a lower dobutamine dose (33 +/- 8 microg/kg/min vs 35 +/- 9 microg/kg/min; p = 0.01). Cardiac arrhythmias occurred more frequently (12% vs 5%; p = 0.001) in patients with AF during DSE. During a follow-up period of 7 years, cardiac death occurred in 5 patients, myocardial infarction in 2 patients, and late revascularization in 10 patients. Prognostic value of DSE for all late cardiac events was similar in patients with AF (HR, 3.0; 95% CI, 0.9 to 9.5) and sinus rhythm (HR, 3.4; 95% CI, 2.7 to 4.3; p = 0.85). CONCLUSION: The prognostic value of DSE for late cardiac events is maintained in patients with AF.

Visualization of elusive structures using intracardiac echocardiography: insights from electrophysiology.

Electrophysiological mapping and ablation techniques are increasingly used to diagnose and treat many types of supraventricular and ventricular tachycardias. These procedures require an intimate knowledge of intracardiac anatomy and their use has led to a renewed interest in visualization of specific structures. This has required collaborative efforts from imaging as well as electrophysiology experts. Classical imaging techniques may be unable to visualize structures involved in arrhythmia mechanisms and therapy. Novel methods, such as intracardiac echocardiography and three-dimensional echocardiography, have been refined and these technological improvements have opened new perspectives for more effective and accurate imaging during electrophysiology procedures. Concurrently, visualization of these structures noticeably improved our ability to identify intracardiac structures. The aim of this review is to provide electrophysiologists with an overview of recent insights into the structure of the heart obtained with intracardiac echocardiography and to indicate to the echo-specialist which structures are potentially important for the electrophysiologist.

Alternating capture of the ventricle and an unusual pacing rate.

The recent improvements in technology of cardiac pacing are often responsible for difficult electrocardiograms at follow-up (Gladstone et al., 1987). Therefore, it seems an advantage that most modern pacemakers include diagnostic software functions to explain the pacing behaviour (event markers, intracardiac electrograms...). In this case report an electrocardiogram, showing pacing dysfunction of a physiologic pacemaker with rate response is presented. It was possible to understand what was happening without electrograms, but confirmation of our interpretation of the pacing behaviour was only possible with telemetric data.

[Treatment with the implantable cardioverter defibrillator (ICD)]. / Behandeling met de implanteerbare cardioverter-defibrillator (ICD).

Interventional techniques in clinical cardiology became important in rhythmology, because it is evident that antiarrhythmic drug therapy has several limitations, and side effects. The implantable cardioverter defibrillator is a very reliable tool in the therapy of ventricular fibrillation and ventricular tachycardia. Conversion of these arrhythmias is associated with the prevention of subsequent sudden cardiac death in patients who received implantation after cardiac arrest, not associated with myocardial infarction or metabolic disturbances. The exact place of the defibrillator in the treatment of ventricular tachycardia remains unsettled, as amiodarone, sotalol and catheter ablation are acceptable treatment modalities for some patients. Furthermore, associated antiarrhythmic drug therapy remains necessary in a large group of patients after implantation. The morbidity and mortality of the recently developed non-thoracotomy devices is low. The potential value of implantable defibrillators in the prevention of cardiac arrest in high-risk patients remains to be studied.

[Intracardial shock for the conversion of chronic atrial fibrillation]. / Intracardiale shocks voor de conversie van chronisch atriumfibrilleren.

Internal cardioversion was attempted in three patients with chronic atrial fibrillation, refractory to conventional external direct current shocks. Endocardiac shocks were delivered between the proximal electrode on a multipolar USCI pacing catheter and a back paddle. This is positioned with the tip proximal of the bundle of His, and the proximal ring electrode floating in the right atrium. Two patients were converted with 200 Joules, one needed 400 Joules. Two of our three patients were chronically maintained in sinus rhythm after the initial conversion, one had recurrence within 24 hours.

Mechanically induced complete atrioventricular block during retrograde catheter ablation of a left-sided incessant tachycardia.

Concern for potentially lethal complications related to transseptal catheterisation, such as perforation of the aorta, has made this approach less attractive over the last decades. Nevertheless, this method is now increasingly being used for ablation of left-sided arrhythmias. We report a transient complication of a retrograde procedure in a patient with a left-sided 'Coumel-type' incessant tachycardia. We had to proceed to transseptal catheterisation, as the complication recurred during the second attempt even when using a less rigid transaortic radiofrequency catheter. The transseptal approach using a less stiff cryoenergy catheter was performed without complications.

First Dutch experience with percutaneous left atrial appendage transcatheter occlusion.

BACKGROUND: Patients with atrial fibrillation (AF) have an increased risk of thromboembolic stroke, dependent on clinical variables. Oral anticoagulation significantly decreases the risk of stroke or embolism, but sometimes this is difficult to manage and may be contraindicated. Approximately 90% of atrial thrombi in nonrheumatic AF are found in the left atrial appendage (LAA). A new device has been developed which allows percutaneous LAA occlusion (PLAATO) and might be an alternative to oral anticoagulation. Feasibility in dogs and humans was described previously. METHODS AND RESULTS: As part of an international multicentre trial, three patients received a percutaneous transcatheter LAA occlusion device. Implantations were performed without general anaesthesia, guided by intracardiac and transoesophageal echocardiography and without major complications. The implantations were well tolerated by the patients, who entered a long-term follow-up to be compared with a historical control group. CONCLUSION: Transseptal percutaneous LAA occlusion is feasible. Its role as an alternative to oral anticoagulation, however, needs to be further defined.

Electrical isolation of pulmonary veins using cryothermal energy: study design and initial results.

In the September 2003 issue of the Netherlands Heart Journal, the wrong figures where inserted in this article. The article is reprinted here with the correct figures. BACKGROUND: Atrial fibrillation (AF) is the most frequently encountered arrhythmia. Radiofrequency pulmonary vein (PV) ablation is promising for symptomatic paroxysmal AF, but is associated with a significant risk of PV stenosis. OBJECTIVES: To assess the efficacy of cryothermal PV ablation and the incidence of PV stenosis. METHODS: Highly symptomatic patients with paroxysmal or persistent AF were eligible for cryothermal ablation. Multislice spiral CT scans were performed before, and three months after ablation. AF burden was assessed using transtelephonic ECG recording and by telephone enquiry. RESULTS: An attempt was made to isolate 27 PVs in 15 patients. In total, 20 PVs could be isolated (74% acute success). No significant difference in PV diameter was seen before and after ablation. Five out of 12 patients with paroxysmal AF were completely without AF after one ablation procedure. An additional two patients reported a significant reduction in symptoms. In the three patients with persistent AF no improvement was reported. CONCLUSION: Cryothermal PV ablation was effective in isolation of the targeted PVs. It appears to be safe, as no PV stenosis was seen in this study three months after the ablation. Taking into account a learning curve, we consider the clinical results to be very promising.

Electrical isolation of pulmonary veins using cryothermal energy: study design and initial results.

BACKGROUND: Atrial fibrillation (AF) is the most frequently encountered arrhythmia. Radiofrequency pulmonary vein (PV) ablation is promising for symptomatic paroxysmal AF, but is associated with a significant risk of PV stenosis. OBJECTIVES: To assess the efficacy of cryothermal PV ablation and the incidence of PV stenosis. METHODS: Highly symptomatic patients with paroxysmal or persistent AF were eligible for cryothermal ablation. Multislice spiral CT scans were performed before, and three months after ablation. AF burden was assessed using transtelephonic ECG recording and by telephonic enquiry. RESULTS: An attempt was made to isolate 27 PVs in 15 patients. In total, 20 PVs could be isolated (74% acute success). No significant difference in PV diameter was seen before and after ablation. Five out of 12 patients with paroxysmal AF were completely without AF after one ablation procedure. An additional two patients reported a significant reduction in symptoms. In the three patients with persistent AF no improvement was reported. CONCLUSION: Cryothermal PV ablation was effective in isolation of the targeted PVs. It appears to be safe, as no PV stenosis was seen in this study three months after the ablation. Taking into account a learning curve, we consider the clinical results to be very promising.

Clinical benefit, survival and adverse events in patients with implantable cardioverter defibrillators: the initial Rotterdam experience.

BACKGROUND: The implantable cardioverter defibrillator (ICD) has become a widely accepted therapy for patients with severe life-threatening ventricular tachyarrhythmias. The aim of this study was to illustrate the possible advantages of ICDs with respect to survival and clinical events. METHODS AND RESULTS: Between 1998 and 2000, 92 patients (aged 58±15 years; ejection fraction 36±15%; coronary artery disease 71%) were treated with an ICD in combination with an endocardial lead system. Benefit of the ICD was estimated as the difference between total cardiac death and the projected death rate of fast ventricular tachyarrhythmias (>200 bpm), assuming that most fast ventricular tachyarrhythmias would have been fatal without termination by the ICD. Adverse events were classified according to European standards. The cardiac mortality rate was 5.5% and 9.8%, at one and two years respectively. The recurrence rate of fast VT (>200 bpm) was 22.4% and 30.2%, at one and two years respectively. The observed difference between cardiac death and projected death was very significant (p=0.002) and suggests a clear benefit from ICD implantation. Low ejection fraction (<35%) and NYHA class ≥II correlated with a higher projected death. The most common adverse event was inappropriate therapy (18%). CONCLUSION: The results from our small series support the existing data that especially patients with poor ejection fraction (<35%) benefit from ICD implantation. The adverse event rate was low. However, inappropriate therapy remains a matter of concern. Given the high workload of correct screening and follow-up, we expect that the actual number of centres in the Netherlands permitted to implant ICDs will be unable to cope with the widening spectrum of ICD indications.

Recommendations for pacemaker implantation for the treatment of atrial tachyarrhythmias and resynchronisation therapy for heart failure: A report from the task force on pacemaker indications of the Dutch Working Group on Cardiac Pacing.

Today, new pacing algorithms and stimulation methods for the prevention and interruption of atrial tachyarrhythmias can be applied on patients who need bradycardia pacing for conventional reasons. In addition, biventricular pacing as additive treatment for patients with severe congestive heart failure due to ventricular systolic dysfunction and prolonged intraventricular conduction has shown to improve symptoms and reduce hospital admissions. These new pacing technologies and the optimising of the pacing programmes are complex, expensive and time-consuming. Based on many clinical studies the indications for these devices are beginning to emerge. To support the cardiologist's decision-making and to prevent waste of effort and resources, the 'ad hoc committee' has provided preliminary recommendations for implantable devices to treat atrial tachyarrhythmias and to extend the treatment of congestive heart failure respectively.

Influence of vagal nervous activity on blood pressure variability.

In our previous studies, it was shown that blood pressure variability was largely independent from the adrenergic nervous system. In the present work, vagal nervous influence on blood pressure variability was analysed both in dogs and in men. In eight chronically instrumented conscious dogs, striking fluctuations of blood pressure were observed when quietly resting; these fluctuations correlate well with fluctuation of heart rate. Atropine abolished all variations both of heart rate and of pressure. Reflex stimulation of vagal tone by neosynephrine increased variability of both parameters. Thus, in dogs, blood pressure variability is related to variability of heart rate which is largely influenced by vagal tone. The same question was approached in seven male volunteers; blood pressure and heart rate were measured automatically every 2 min, during 1 h, before and after atropine. In control conditions, no correlation between variability of heart rate and of blood pressure was observed. Atropine clearly decreased variability of heart rate and of diastolic blood pressure. These data confirm the animal results; however, the influence of vagal nerves on variability is less pronounced in man than in dogs.

Adenosine testing after cryoballoon pulmonary vein isolation improves long-term clinical outcome.

BACKGROUND: Adenosine infusion after pulmonary vein isolation (PVI) with radiofrequency energy reveals dormant muscular sleeves and predicts atrial fibrillation (AF) recurrence. The aim of our study was to determine whether adenosine could reveal dormant PV sleeves after cryoballoon isolation and study its effect on long-term recurrence of AF. METHODS: Patients with paroxysmal AF underwent cryoballoon PVI. After PVI, adenosine 25 mg was infused to test for dormant muscular sleeves in each vein. If reconnection under adenosine was shown, further cryoballoon ablation was performed until no more reconnection occurred. Follow-up was performed with ECG, 24-h Holter recording, and a symptom questionnaire at three monthly intervals. Transtelephonic Holter monitoring was performed for 1 month before and 3 months after PVI. Patients who underwent cryoballoon PVI without adenosine administration were used as controls for comparison. RESULTS: In the study group (n = 34, 24 males), adenosine revealed dormant sleeves in 9/132 (8 %) veins, and 7/34 (21 %) patients. All but one vein was further treated until the dormant sleeves were isolated. During a mean follow-up of 520 ± 147 days, 23/34 (68 %) patients were free of AF without antiarrhythmic drugs (AADs). In the control group (n = 65, 46 males), 29/65 (46 %) were free of AF without AADs. There were significantly less AF recurrences in the study group (p = 0.04). CONCLUSIONS: Adenosine administration after cryoballoon PVI reveals dormant muscular sleeves in 21 % of patients. Clinical follow-up shows that adenosine testing is effective in reducing AF recurrence after cryoballoon ablation.

Imaging of a coronary artery bypass graft during coronary sinus venography.

Retrograde coronary sinus perfusion to maintain viability during cardiac surgery means that a connection via the capillary system to the coronary arteries, and potentially bypass grafts, may be possible. Coronary sinus (CS) venography prior to resynchronisation therapy in this patient with previous bypass grafting was associated with visualisation of these grafts.