Silent Cerebral Events after Atrial Fibrillation Ablation - Overview and Current Data.

Silent cerebral lesions (SCL) have been identified on brain magnetic resonance imaging (MRI) in apparently asymptomatic patients after cardiovascular procedures. After atrial fibrillation (AF) ablation incidences range from 1 to over 40% depending upon different factors. MRI definition should include diffusion weighted imaging (DWI) to detect hyperintensities (bright spots) due to acute brain ischemia correlated with a hypointensity in the apparent diffusion coefficient mapping (ADC-map) to rule out artifacts. The genesis of SCL appears to be multifactorial and appears to be a result of embolic events either from gaseous or solid particles. The MRI pattern appears to be comparable not hinting towards a specific mechanism. One may distinguish two different MRI definition: one, more sensitive, for silent ischemic events (SCE) not proven to be related to cell death (DWI positive but FLAIR negative); and one for SCL that are due to edema caused by cell death which will lead to glial cell scar formation (DWI positive and FLAIR positive). For ease of data interpretation, future studies should ensure both definitions, and that DWI and FLAIR data is acquired using identical slice thickness and orientation. Risk factors associated with increased SCL-incidences involve patient-specific, technology-associated and procedural determinants. When using a high-sensitive MRI definition differences in SCE-rates in between technologies appear to be less prominent. Further studies on the effects of different periprocedural anticoagulation regimen, different steps of the ablation procedure and new technologies are needed. For now, SCL incidence may determine the thrombogenic potential of an ablation technology and further studies to reduce or avoid SCL generation are desirable. It appears reasonable, that any SCE should be avoided.

Catheter ablation of electrical storm in a collaborative hospital network.

An electrical storm (ES) is defined as multiple ventricular arrhythmia episodes leading to implantable cardioverter defibrillator interventions. Although conventional rhythm stabilization might be of help acutely, ES involves high mortality and morbidity. We evaluated the effect of catheter ablation strategies in the setting of an interhospital collaborative network on the recurrence of ventricular arrhythmia episodes and mortality in patients with ES. Consecutive patients presenting for invasive treatment of ES from December 2007 to December 2009 were included. All patients underwent catheter ablation of ventricular arrhythmia. The strategies were adapted to the individual cardiac pathologic features. The follow-up examination constituted periodic implantable cardioverter defibrillator interrogation. A total of 32 patients were included. Of the 32 patients, 29 (91%) had monomorphic ventricular tachycardia and 3 ventricular fibrillation. The mean number of implantable cardioverter defibrillator-treated episodes within 7 days before ablation was 16 ± 11. Of the 32 patients, 27 underwent ablation within 24 hours after admission, and 5 underwent acute ablation within 8 hours. In 3 patients, epicardial ablation was performed. In all but 2 patients (6%), the clinical arrhythmia was successfully ablated. During a median follow-up of 15 months, 10 patients (31%) had recurrences of sustained ventricular arrhythmia, including 2 patients (6%) with recurrent ES. Three patients (9%) died during the follow-up period. In conclusion, catheter ablation effectively suppressed ventricular arrhythmia midterm recurrences in patients presenting with ES. Catheter ablation is complex in these severely sick patients. The recurrence rate of ventricular arrhythmia appears to be 31% and the mortality rate to be 9%. Collaborative hospital networks to increase the prompt availability of ES ablation might help to optimize the ES outcome.

Non-invasive determination of the optimized atrioventricular delay in patients with implanted biventricular pacing devices.

BACKGROUND: Biventricular (BiV) is extensively used in the treatment of congestive heart failure but so far no recommendations for optimized programming of atrioventricular-delay (AVD) settings have been proposed. Can AVD optimization be performed using a simple formula based on non-invasive doppler-echocardiography? METHODS: 25 patients (ejection fraction 30+/-8%) received BiV ICDs. Doppler-echocardiographic evaluation of diastolic and systolic flow was performed for different AVDs (30ms to 150ms) and different stimulation sites (left ventricular (LV), right ventricular and BiV). The optimal atrioventricular delay was calculated applying a simple formula based on systolic and diastolic mechanical delays determined during doppler-echocardiography. RESULTS: The mean optimal AVD was calculated to be 112+/-29ms (50 to 180ms) for BiV, 95+/-30ms (65 to 150ms) for LV and 75+/-28ms (40 to 125ms) for right ventricular pacing with wide interindividual variations. Compared to suboptimal AVDs diastolic optimization improved preejection and ejection intervals independent to pacing site. Optimization of the AVD significantly increased ejection time during BiV pacing (279ms versus 266ms; p<0.05). Compared to LV or right ventricular pacing BiV pacing produced the shortest mean pre-ejection and longest ejection intervals as parameters of improved systolic ventricular contractile synchrony. Diastolic filling times were longest during BiV pacing compared to LV or RV pacing. CONCLUSIONS: Individual programming of BiV pacing devices increases hemodynamic benefit when implementing the inter-individually widely varying electromechanical delays. Optimization applying a simple formula not only improves diastolic ventricular filling but also increases systolic functional parameters.

Reaction patterns of the tracheobronchial wall to implanted noncovered metal stents.

BACKGROUND: Endoluminal implantation of stents has evolved as a nonsurgical treatment option for stenosis of the central airways. Based on the favorable results in treatment of tumorous tracheobronchial stenosis, stenting has been introduced into the therapy of nonmalignant stenosis. AIM: To study the long-term biocompatibility and incorporation of implanted bronchial stents based on the pathoanatomic reaction of the tracheobronchial system in humans. The incorporation of bronchial stents was documented, with specific interest in transformation or induction of dysplasia in the implantation zone. METHODS: The tracheobronchial reaction was studied in 18 patients 2 days to 18 months after implantation of 24 noncovered metal stents (Wallstent; Schneider; Bülach, Switzerland; n = 8; and Ultraflex; Boston Scientific; Natick, MA; n = 16). RESULTS: Stenting produced slow papillomatous growth of granulative tissue through the interfilamentary space of the stents. A nonspecific inflammatory response of nontumorous tissue could be documented. Sparse spots of superficial squamous cells occurred. No epithelial dysplasia or giant cells were detected within the stented region. The number of superficial ciliated cells in the implantation zone was markedly reduced. CONCLUSION: After stent insertion in the upper airways, no malignant transformation of initially nontumorous tissue occurs. Stenting seems to be a safe therapy option when considered even for nonmalignant airway stenoses.

Occlusion of pseudoaneurysms using human or bovine thrombin using contrast-enhanced ultrasound guidance.

Percutaneous thrombin occlusion of pseudoaneurysms complicating invasive coronary interventions has emerged as a useful therapeutic tool. To facilitate thrombin occlusion and make the procedure even more secure, preinjection of echo contrast medium during duplex ultrasound was tested in 132 patients. Complete and immediate occlusion of the pseudoaneurysm was achieved in 99.2% (131 of 132 patients). No complications related to the injection of thrombin were documented. Contrast-enhanced ultrasound-guided thrombin occlusion was a safe and effective therapeutic option. In aneurysms with complex morphology or multiple cavities, preinjection of contrast medium was helpful for documenting the flow pattern.

Left atrial versus bi-atrial Maze operation using intraoperatively cooled-tip radiofrequency ablation in patients undergoing open-heart surgery: safety and efficacy.

OBJECTIVES: We sought to determine whether limited left atrial Maze surgery encircling each of the pulmonary veins, using cooled-tip radiofrequency (RF) ablation, is as effective as the bi-atrial approach? BACKGROUND: The original Cox/Maze operation effectively restores sinus rhythm (SR) in patients with atrial fibrillation (AF). Ablation procedures aimed at eliminating pulmonary vein foci have produced promising short-term success. METHODS: This was a prospective analysis of patients with chronic AF undergoing open-heart surgery in addition to the Maze operation, using intraoperatively cooled-tip RF ablation either in the left atrium alone (group A) or in both atria (group B). RESULTS: Patients in group A (n = 21) and group B (n = 49) did not differ in terms of their baseline characteristics. Concomitant open-heart surgical procedures included mitral valve replacement (3 vs. 25), mitral valve plasty (0 vs. 2), mitral and aortic valve replacement (1 vs. 1), aortic valve replacement (4 vs. 6) and coronary artery bypass grafting (13 vs. 15) in groups A and B, respectively. Follow-up ranged from 1 to 50 months. The overall cumulative rates of SR were 82% in group A and 75% in group B, without a statistically significant difference (p = 0.571). Bi-atrial contraction was revealed in 92.3% of patients in SR in group A and in 79.2% in group B. The cumulative survival rates were 90.5% in group A and 77.9% in group B (p = 0.880). CONCLUSIONS: A left or bi-atrial Maze operation using intraoperatively cooled-tip RF ablation can safely be combined with open-heart surgery. A left atrial Maze procedure seems to be as effective as the bi-atrial procedure and restores SR in 82% of patients.