Global multielectrode contact-mapping plus ablation with a single catheter in patients with atrial fibrillation: Global AF study.

INTRODUCTION: The critical question for technological advancement of catheter ablation of atrial fibrillation (AF) is whether a creative new concept can combine and even improve the options of single-tip catheters with the simplicity of the use of balloon catheters. Herein are described the results from the first clinical study of a new multielectrode contact-mapping plus ablation array (Globe) offering such a complete solution. METHODS AND RESULTS: The multielectrode Globe array consists of 16 flat ribs with 122 gold-plated electrodes. Each electrode can record electrograms, ablate, pace, and can measure tissue contact and temperature. Single-shot pulmonary vein isolation (PVI) is possible with temperature-guided ablation of up to 24 electrodes simultaneously with automatic, individual power control of every electrode. Sixty patients with symptomatic AF underwent PVI using the Globe. In all sixty patients, acute PVI was achieved in 232 of 234 attempted PVs (99.1%). In 34 patients treated with "single-hot-shot" ablation, PVI was achieved in 136 of 136 PVs (100%). Single-procedure 12-month freedom from AF off antiarrhythmic drugs in the "single-hot-shot" group was 75.5% and freedom from AF/atrial tachycardia 72.3%. In two patients, pericardial tamponade was observed, one after a transseptal puncture, and one during array insertion with an over-advanced sheath. There were no other device-related serious adverse events, including stroke, PV stenosis, esophageal perforation, or phrenic nerve palsy. CONCLUSIONS: In this first clinical series, the Globe catheter was found to be an easy-to-use system for single-shot PVI. The continuously updated multielectrode voltage and activation mapping data indicate future options for mapping and ablation beyond PVI.

A novel ablation approach in atrial fibrillation patients undergoing fibrotic-based substrate modification: Targeting the Bachmann's bundle?

INTRODUCTION: Box isolation of fibrotic areas (BIFA) is a promising ablation approach for atrial fibrillation (AF) patients. However, complete isolation of fibrotic anteroseptal left atrial area, where Bachmann's bundle is blending into the left atrial myocardium, is very specific and complex. METHODS AND RESULTS: In 34 AF patients with anteroseptal fibrosis, circumferential BIFA was performed in addition to pulmonary vein isolation. In 8 of 34 patients, complete isolation of the fibrotic area was achieved with BIFA alone. In 26 of 34 patients, a decrease in voltage amplitude with or without conduction delay was observed after box ablation but no complete isolation. Activation mapping and characteristic unipolar potentials revealed earliest activation inside the box from one (73%), two (15%), or three (12%) remaining inputs, in the region of Bachmann's bundle insertion. Focal ablation inside the box (mean radiofrequency impulses: 1.7 ± 0.4, mean radiofrequency time: 70 ± 19 seconds) led to complete isolation of the fibrotic area in 25 of 26 patients. Overall, 97% of anteroseptal boxes were completely isolated with additional focal ablation in the study group compared to 21% in the control group with BIFA alone (33/34 vs. 7/34, P < 0.001). Time of left atrial activation decreased significantly by 25% after complete box isolation (P < 0.001). After a single procedure, 12-month arrhythmia-free survival was 82% with additional focal ablation compared to 71% in the control group (P = 0.2). CONCLUSION: Targeted and focal ablation in the region of Bachmann's bundle is a novel and feasible technique to achieve complete isolation of the left atrial anteroseptal fibrotic area.

Box Isolation of fibrotic areas: A substrate modification approach in atrial fibrillation patients.

In the last years, atrial fibrosis was shown to be an independent predictor of procedural failure in patients with paroxysmal and persistent atrial fibrillation. Ablation strategies have been developed to improve the outcome of catheter ablation by targeting detected areas of fibrosis, based either on endocardial voltage mapping or cardiac magnetic resonance. Box isolation of fibrotic areas (BIFA) is a new and promising patient-tailored ablation strategy for atrial fibrillation patients targeting substantial fibrotic areas by circumferential isolation of left atrial fibrosis.

Global multielectrode contact mapping plus ablation with a single catheter: Preclinical and preliminary experience in humans with atrial fibrillation.

INTRODUCTION: One question for the technological advancement of catheter ablation of atrial fibrillation (AF) is whether a creative new concept can combine and even improve the diagnostic mapping options of single-tip and basket catheters with the simplicity of the use of balloon catheters for ablation. Herein, we describe the first in-human experience with a single catheter offering such a complete solution. METHODS AND RESULTS: A new catheter (Globe® ) with a distal multielectrode array consisting of 16 ribs with 122 gold-plated electrodes was used. Each electrode can ablate, pace, and can measure tissue contact, temperature, current, and intracardiac electrograms. The Globe was deployed and removed without difficulty in all 3 patients. Complete pulmonary vein isolation (PVI) was achieved in all 12 veins. In 10 veins, PVI was achieved with a single placement in front of the respective vein ("single circle isolation"). In one subject, the device was repositioned due to the esophagus location. In the other subject, a single gap was observed after circumferential ablation of the right inferior PV. After precise gap identification, the device was adjusted slightly for improved contact at that region, and reablation resulted in immediate PVI. CONCLUSIONS: PVI isolation could be performed with the new multielectrode array Globe in all 12 PVs offering the option for easy handling and fast "single-shot" PVI. Several continuously updated mapping types from 122 electrodes even in real time during ablation demonstrate the capability to go beyond PVI for voltage mapping plus substrate modification, and for rotor mapping plus rotor ablation.

Catheter ablation of atrial fibrillation with box isolation of fibrotic areas: Lessons on fibrosis distribution and extent, clinical characteristics, and their impact on long-term outcome.

INTRODUCTION: The BIFA concept (box isolation of fibrotic areas) supplementing pulmonary vein isolation (PVI) was implemented in atrial fibrillation (AF) patients with fibrotic atrial cardiomyopathy (FACM) to improve catheter ablation outcomes. METHODS AND RESULTS: Ninety-two patients with FACM underwent PVI + BIFA. We investigated patient characteristics (58 persistent/34 paroxysmal, 68 ± 8 years, LA 44 ± 7 mm, CHA2 DS2 -VASc 2.6 ± 1.3, FACM I: 15.2%, II: 53.3%, III: 26.1%, IV: 5.4%), periprocedural data concerning fibrosis extent/distribution, and their impact on outcome. Based on severe fibrosis areas (SFAs) of 13.5 ± 13.9 cm2 detected by voltage mapping, 1.4 ± 0.5 boxes (n = 1-3, 2.2-35.3 cm2 ) were applied in the left atrium. With higher grade FACM, SFAs increased and maximum voltage decreased (I/IV: 6.29/3.18 mV). Anterior (ant.) SFAs were found to be more common and larger than posterior (post.) SFAs (58.3% vs. 42.6%, ant. 8.0 ± 8.0 vs. post. 4.7 ± 6.8 cm2 ). In 40 of 92 (43%) patients, both atrial walls were affected with rare cases of solely post. fibrosis (6 of 92, 6.6%). Women (39 of 92, 42%) showed FACM III+IV more often than men (P = 0.022) and can still present paroxysmal while persistent males are more likely to have FACM I-II. Single and multiple procedure (1.2/patient) success was 69% and 83% after 16 ± 8 months with an unfavorable impact of large SFA size, both-sided fibrosis and reduced maximum voltage, independently of patient characteristics and AF type. CONCLUSION: FACM patients are a challenging AF subgroup for catheter ablation. Women seem to show FACM III+IV more often than men. The distribution of left atrial fibrosis is variable but more pronounced anteriorly. Atrial disease is characterized by SFA size but also maximum voltage reduction, both with implications on ablation outcome. Using BIFA, success rates of patients without fibrosis can be approached but are limited in FACM III+IV.

Therapeutic Approaches to Atrial Fibrillation Ablation Targeting Atrial Fibrosis.

Atrial fibrosis is the fundamental histopathologic finding in atrial fibrillation (AF) patients and an important predictor of ablation failure beyond pulmonary vein isolation. There is wide variation in the extent and localization of left atrial fibrosis in patients with paroxysmal and nonparoxysmal AF. Box isolation of fibrotic areas is an effective rhythm control concept in patients with paroxysmal AF despite durable pulmonary vein isolation, and this strategy has recently been implemented successfully in initial AF ablation procedures in addition to pulmonary vein isolation for patients with nonparoxysmal AF. In contrast, the time for "empirical" lines or other nonindividualized substrate modifications seems over.

Box Isolation of Fibrotic Areas (BIFA): A Patient-Tailored Substrate Modification Approach for Ablation of Atrial Fibrillation.

BACKGROUND: Catheter ablation strategies beyond pulmonary vein isolation (PVI) for treatment of atrial fibrillation (AF) are less well defined. Increasing clinical data indicate that atrial fibrosis is a critical common left atrial (LA) substrate in AF patients (pts). OBJECTIVE: We applied a new substrate modification concept according to the individual fibrotic substrate as estimated from electroanatomic voltage mapping (EAVM) in 41 pts undergoing catheter ablation of AF. RESULTS: First, EAVM during sinus rhythm was done in redo cases of 10 pts with paroxysmal AF despite durable PVI. Confluent low-voltage areas (LVA) were found in all pts and were targeted with circumferential isolation, so-called box isolation of fibrotic areas (BIFA). This strategy led to stable sinus rhythm in 9/10 pts and was transferred prospectively to first procedures of 31 pts with nonparoxysmal AF. In 13 pts (42%), no LVA (<0.5 mV) were identified, and only PVI was performed. In 18 pts (58%), additional BIFA strategies were applied (posterior box in 5, anterior box in 7, posterior plus anterior box in 5, no box in 1 due to diffuse fibrosis). Mean follow-up was 12.5 ± 2.4 months. Single-procedure freedom from AF/atrial tachycardia was achieved in 72.2% of pts and in 83.3% of pts with 1.17 procedures/patient. CONCLUSIONS: In approximately 40% of pts with nonparoxysmal AF, no substantial LVA were identified, and PVI alone showed high success rate. In pts with paroxysmal AF despite durable PVI and in approximately 60% of pts with nonparoxysmal AF, individually localized LVA were identified and could be targeted successfully with the BIFA strategy.

A review of computer-based simulators for ultrasound training.

SUMMARY STATEMENT: Computer-based simulators for ultrasound training are a topic of recent interest. During the last 15 years, many different systems and methods have been proposed. This article provides an overview and classification of systems in this domain and a discussion of their advantages. Systems are classified and discussed according to the image simulation method, user interactions and medical applications. Computer simulation of ultrasound has one key advantage over traditional training. It enables novel training concepts, for example, through advanced visualization, case databases, and automatically generated feedback. Qualitative evaluations have mainly shown positive learning effects. However, few quantitative evaluations have been performed and long-term effects have to be examined.

Efficiency of 7.2% hypertonic saline hydroxyethyl starch 200/0.5 versus mannitol 15% in the treatment of increased intracranial pressure in neurosurgical patients - a randomized clinical trial [ISRCTN62699180].

INTRODUCTION: This prospective randomized clinical study investigated the efficacy and safety of 7.2% hypertonic saline hydroxyethyl starch 200/0.5 (7.2% NaCl/HES 200/0.5) in comparison with 15% mannitol in the treatment of increased intracranial pressure (ICP). METHODS: Forty neurosurgical patients at risk of increased ICP were randomized to receive either 7.2% NaCl/HES 200/0.5 or 15% mannitol at a defined infusion rate, which was stopped when ICP was < 15 mmHg. RESULTS: Of the 40 patients, 17 patients received 7.2% NaCl/HES 200/0.5 and 15 received mannitol 15%. In eight patients, ICP did not exceed 20 mmHg so treatment was not necessary. Both drugs decreased ICP below 15 mmHg (p < 0.0001); 7.2% NaCl/HES 200/0.5 within 6.0 (1.2-15.0) min (all results are presented as median (minimum-maximum range)) and mannitol within 8.7 (4.2-19.9) min (p < 0.0002). 7.2% NaCl/HES 200/0.5 caused a greater decrease in ICP than mannitol (57% vs 48%; p < 0.01). The cerebral perfusion pressure was increased from 60 (39-78) mmHg to 72 (54-85) mmHg by infusion with 7.2% NaCl/HES 200/0.5 (p < 0.0001) and from 61 (47-71) mmHg to 70 (50-79) mmHg with mannitol (p < 0.0001). The mean arterial pressure was increased by 3.7% during the infusion of 7.2% NaCl/HES 200/0.5 but was not altered by mannitol. There were no clinically relevant effects on electrolyte concentrations and osmolarity in the blood. The mean effective dose to achieve an ICP below 15 mmHg was 1.4 (0.3-3.1) ml/kg for 7.2% NaCl/HES 200/0.5 and 1.8 (0.45-6.5) ml/kg for mannitol (p < 0.05). CONCLUSION: 7.2% NaCl/HES 200/0.5 is more effective than mannitol 15% in the treatment of increased ICP. A dose of 1.4 ml/kg of 7.2% NaCl/HES 200/0.5 can be recommended as effective and safe. The advantage of 7.2% NaCl/HES 200/0.5 might be explained by local osmotic effects, because there were no clinically relevant differences in hemodynamic clinical chemistry parameters.

Influence of moderate and profound hyperventilation on cerebral blood flow, oxygenation and metabolism.

OBJECTIVE: The aim of the present study was to examine the impact of moderate and profound hyperventilation on regional cerebral blood flow (rCBF), oxygenation and metabolism. MATERIALS AND METHODS: Twelve anesthetized pigs were subjected to moderate (mHV) and profound (pHV) hyperventilation (target arterial pO(2): 30 and 20 mmHg, respectively) for 30 min each, after baseline normoventilation (BL) for 1 h. Local cerebral extracellular fluid (ECF) concentrations of glucose, lactate, pyruvate and glutamate as well as brain tissue oxygenation (p(ti)O(2)) were monitored using microdialysis and a Licox oxygen sensor, respectively. In nine pigs, regional cerebral blood flow (rCBF) was also continuously measured via a thermal diffusion system. RESULTS: Both moderate and profound hyperventilation resulted in a significant decrease in rCBF (BL: 37.9+/-4.3 ml/100 g/min; mHV: 29.4+/-3.6 ml/100 g/min; pHV: 23.6+/-4.7 ml/100 g/min; p<0.05) and p(ti)O(2) (BL: 22.7+/-4.1 mmHg; mHV: 18.9+/-4.9 mmHg; pHV: 13.0+/-2.2 mmHg; p<0.05). A p(ti)O(2) decrease below the critical threshold of 10 mmHg was induced in three animals by moderate hyperventilation and in five animals by profound hyperventilation. Furthermore, significant increases in lactate (BL: 1.06+/-0.18 mmol/l; mHV: 1.36+/-0.20 mmol/l; pHV: 1.67+/-0.17 mmol/l; p<0.005), pyruvate (BL: 46.4+/-7.8 micromol/l; mHV: 58.0+/-10.3 micromol/l; pHV: 66.1+/-12.7 micromol/l; p<0.05), and lactate/glucose ratio were observed during hyperventilation. (Data are presented as mean+/-S.E.M.) CONCLUSIONS: Both moderate and profound hyperventilation may result in insufficient regional oxygen supply and anaerobic metabolism, even in the uninjured brain. Therefore, the use of hyperventilation cannot be considered as a safe procedure and should either be avoided or used with extreme caution.

Experiences with continuous intra-arterial blood gas monitoring: precision and drift of a pure optode-system.

OBJECTIVE: The utility of continuous intra-arterial blood gas analysis (CBGA) with combined electrochemical and optode sensors has been demonstrated. More recently, a pure optode sensor with a changed sensing element architecture has become available. The aim was to determine the measurement accuracy and long-term stability of the new sensor. DESIGN: A prospective explorative study was performed. Simultaneous measurements of intermittent blood gas analyses (IBGA) (ABL 610, Radiometer, Copenhagen) and CBGA (Diametrics Medical, High Wycombe, Bucks., UK) were compared using Bland-Altman analysis. PATIENTS: Twenty-five patients admitted to the ICU and requiring mechanical ventilation for an expected minimum of about 96 h were included. RESULTS: Mean monitoring time was 106.1 (range 15-231) hours. Bias and precision for PO(2 )were -0.2 kPa (1%)+/-1.8 kPa (9.5%); PCO(2): 0.03 kPa (0.6%)+/-0.44 kPa (9.3%); pH: -0.001 (0.01%)+/-0.04 (0.45%). The sensor showed no change of measurement characteristics during 4 days of measurement. However, in 69 cases continuous monitoring was interrupted (reversible sudden drops of PO(2) measurement) possibly caused by thrombotic deposition and/or sensor bending and accidental sensor retraction. CONCLUSIONS: The precision and bias of the PCO(2)- and pH-sensing elements were in line with the findings of the older sensor technology. The possibility that the PO(2) optode could offer greater accuracy than the older technology is suggested by comparisons with results reported in previous studies. No sensor drift occurred during long-term measurement over more than 4 days.

Vertebral autograft used as bone transplant for anterior cervical corpectomy: technical note.

OBJECTIVE: In this prospective patient study, we used a surgical technique for autograft bone fusion during anterior cervical corpectomy (ACC) in patients experiencing cervical spondylotic myelopathy. We packed the resected bone material of the corpectomy into a titanium mesh cage. To evaluate the efficacy of our autograft technique, we analyzed the results according to neurological outcome, radiological outcome, and complications. METHODS: Between 1995 and 1998, 27 ACC operations were performed for cervical spondylotic myelopathy caused by multisegmental cervical spondylosis. In all patients, decompression of the cervical canal and/or spinal nerve roots was performed by a median cervical corpectomy by an anterior approach. After the ACC was completed, a titanium mesh cage, which was variable in diameter and length, was filled with morselized and impacted bone material from the cervical corpectomy and was then implanted. An anterior cervical plate was placed in all patients to achieve primary stability of the cervical vertebral column. Age, sex, pre- and postoperative myelopathy, number of decompressed levels, radiological results, and complications were assessed. The severity of myelopathy was graded according to the scoring system of the Japanese Orthopaedic Association. RESULTS: Symptomatic improvement of neurological deficits was achieved in 80% of the patients. The mean preoperative Japanese Orthopaedic Association score improved from 13.1 to 15.2 postoperatively (P < 0.05). No patient demonstrated worsening of myelopathic symptoms. Radiological follow-up studies demonstrated complete bony fusion in all patients. A vertical movement of 2.25 +/- 0.43 mm of the titanium cage into the adjacent vertebral bodies was observed in 24 patients. In patients with either a lordotic or neutral cervical spinal axis postoperatively, the axis remained unchanged during the entire follow-up period. CONCLUSION: The results of this study demonstrate that transplantation of autograft bone material harvested during the ACC integrated well in the cage and in the adjacent vertebral bodies. Thus, complications associated with explantation of autograft material from other donor sites, e.g., the iliac crest, could be avoided. The early postoperative and midterm follow-up periods provided no evidence of morphological or functional instability of the operated cervical segments when this autograft technique was used in combination with cervical instrumentation.