Christian Eickholt

Initial results of using a novel irrigated multielectrode mapping and ablation catheter for pulmonary vein isolation

BACKGROUND Pulmonary vein isolation (PVI) as a cornerstone for catheter ablation of atrial fibrillation (AF) remains a complex and time-consuming procedure. OBJECTIVE To assess feasibility, safety, and acute efficacy of a novel irrigated multielectrode ablation catheter guided by an electroanatomic mapping system for PVI in patients with paroxysmal AF. METHODS Twenty-five consecutive patients (60 ± 10 years) with paroxysmal AF underwent PVI by using a novel decapolar mapping and ablation catheter (nMARQ catheter, Biosense Webster Inc, Diamond Bar, CA). Ablation was guided by electroanatomic mapping allowing radiofrequency (RF) energy delivery in the antral region of pulmonary veins (PVs) from 10 irrigated electrodes simultaneously. The day after ablation, cardiac magnetic resonance imaging was performed routinely in order to assess for potential acute PV stenosis. RESULTS Overall, 97 of 97 (100%) targeted PVs could be isolated with a mean of 27 ± 11 RF applications and a mean total burning time of 15 ± 6 minutes per patient. The total procedure time from femoral vein access to catheter withdrawal was 110 ± 31 minutes, including a mean total fluoroscopy time of 23 ± 9 minutes. On average, 6 ± 3 RF impulses with a maximum of 25 W were applied per vein. After a short learning curve, procedure, fluoroscopy, and total burning times decreased to 94 ± 16, 16 ± 3, and 9 ± 2 minutes, respectively (P < .05). Entrance and exit blocks could be verified by placing the ablation catheter into 90 of 97 (93%) PVs in 18 of 25 (72%) patients. No procedure-related complications were observed, especially no acute PV stenosis could be detected. CONCLUSIONS The use of a novel irrigated multielectrode ablation system for PVI is feasible and safe, resulting in acute isolation of all targeted PVs with no complications and short procedure times. Sustainability of these initial results has to be confirmed in long-term efficacy and follow-up trials.

Left Atrial Appendage Closure Guided by Integrated Echocardiography and Fluoroscopy Imaging Reduces Radiation Exposure

Aims To investigate whether percutaneous left atrial appendage (LAA) closure guided by automated real-time integration of 2D-/3D-transesophageal echocardiography (TEE) and fluoroscopy imaging results in decreased radiation exposure. Methods and Results In this open-label single-center study LAA closure (AmplatzerTM Cardiac Plug) was performed in 34 consecutive patients (8 women; 73.1±8.5 years) with (n = 17, EN+) or without (n = 17, EN-) integrated echocardiography/fluoroscopy imaging guidance (EchoNavigator® [EN]; Philips Healthcare). There were no significant differences in baseline characteristics between both groups. Successful LAA closure was documented in all patients. Radiation dose was reduced in the EN+ group about 52% (EN+: 48.5±30.7 vs. EN-: 93.9±64.4 Gy/cm2; p = 0.01). Corresponding to the radiation dose fluoroscopy time was reduced (EN+: 16.7±7 vs. EN-: 24.0±11.4 min; p = 0.035). These advantages were not at the cost of increased procedure time (89.6±28.8 vs. 90.1±30.2 min; p = 0.96) or periprocedural complications. Contrast media amount was comparable between both groups (172.3±92.7 vs. 197.5±127.8 ml; p = 0.53). During short-term follow-up of at least 3 months (mean: 8.1±5.9 months) no device-related events occurred. Conclusions Automated real-time integration of echocardiography and fluoroscopy can be incorporated into procedural work-flow of percutaneous left atrial appendage closure without prolonging procedure time. This approach results in a relevant reduction of radiation exposure. Trial Registration ClinicalTrials.gov NCT01262508

Disruption of cardiac cholinergic neurons enhances susceptibility to ventricular arrhythmias.

The parasympathetic nervous system plays an important role in the pathophysiology of atrial fibrillation. Catheter ablation, a minimally invasive procedure deactivating abnormal firing cardiac tissue, is increasingly becoming the therapy of choice for atrial fibrillation. This is inevitably associated with the obliteration of cardiac cholinergic neurons. However, the impact on ventricular electrophysiology is unclear. Here we show that cardiac cholinergic neurons modulate ventricular electrophysiology. Mechanical disruption or pharmacological blockade of parasympathetic innervation shortens ventricular refractory periods, increases the incidence of ventricular arrhythmia and decreases ventricular cAMP levels in murine hearts. Immunohistochemistry confirmed ventricular cholinergic innervation, revealing parasympathetic fibres running from the atria to the ventricles parallel to sympathetic fibres. In humans, catheter ablation of atrial fibrillation, which is accompanied by accidental parasympathetic and concomitant sympathetic denervation, raises the burden of premature ventricular complexes. In summary, our results demonstrate an influence of cardiac cholinergic neurons on the regulation of ventricular function and arrhythmogenesis.

Characterization, Mapping, and Ablation of Complex Atrial Tachycardia: Initial Experience With a Novel Method of Ultra High‐Density 3D Mapping

Conventional mapping of complex atrial tachycardias (ATs) can be challenging. Thus, we evaluated feasibility and utility of a novel, ultra high‐density 3D mapping approach to characterize and map AT in these cases.

Pulse Arrival Time as surrogate for systolic blood pressure changes during impending neurally mediated syncope

Blood pressure regulation failures cause neurally mediated syncope often resulting in a fall. A warning device might help to make patients aware of an impending critical event or even trigger the patient to perform countermeasures such as lying down or isometric exercises. We previously demonstrated that the Pulse Arrival Time (PAT) methodology is a potential approach to enable early detection of impending faints. The aim of the present study was to evaluate whether PAT can be used as an easy to measure beat-to-beat surrogate for systolic blood pressure (SBP) changes during a passive standing exercise (head-up tilt table testing (HUTT)). A significant PAT increase of more than 10 % was accompanied with a critical SBP decrease in syncope patients. Although PAT is in general not considered as a good measure of absolute blood pressure we found strong correlations (R>;0.89, P<;0.01) of SBP and PAT after PAT began to increase. Therefore, our data suggest that the pulse arrival time is useful to monitor blood pressure changes in patients with neurally mediated syncope. This might open up new avenues to prevent falls in these patients.

Assessment of cardiovascular function from multi-Gaussian fitting of a finger photoplethysmogram.

Monitoring of cardiovascular function on a beat-to-beat basis is fundamental for protecting patients in different settings including emergency medicine and interventional cardiology, but still faces technical challenges and several limitations. In the present study, we propose a new method for the extraction of cardiovascular performance surrogates from analysis of the photoplethysmographic (PPG) signal alone.We propose using a multi-Gaussian (MG) model consisting of five Gaussian functions to decompose the PPG pulses into its main physiological components. From the analysis of these components, we aim to extract estimators of the left ventricular ejection time, blood pressure and vascular tone changes. Using a multi-derivative analysis of the components related with the systolic ejection, we investigate which are the characteristic points that best define the left ventricular ejection time (LVET). Six LVET estimates were compared with the echocardiographic LVET in a database comprising 68 healthy and cardiovascular diseased volunteers. The best LVET estimate achieved a low absolute error (15.41   ±   13.66 ms), and a high correlation (ρ = 0.78) with the echocardiographic reference.To assess the potential use of the temporal and morphological characteristics of the proposed MG model components as surrogates for blood pressure and vascular tone, six parameters have been investigated: the stiffness index (SI), the T1_d and T1_2 (defined as the time span between the MG model forward and reflected waves), the reflection index (RI), the R1_d and the R1_2 (defined as their amplitude ratio). Their association to reference values of blood pressure and total peripheral resistance was investigated in 43 volunteers exhibiting hemodynamic instability. A good correlation was found between the majority of the extracted and reference parameters, with an exception to R1_2 (amplitude ratio between the main forward wave and the first reflection wave), which correlated low with all the reference parameters. The highest correlation ([Formula: see text] = 0.45) was found between T1_2 and the total peripheral resistance index (TPRI); while in the patients that experienced syncope, the highest agreement ([Formula: see text] = 0.57) was found between SI and systolic blood pressure (SBP) and mean blood pressure (MBP).In conclusion, the presented method for the extraction of surrogates of cardiovascular performance might improve patient monitoring and warrants further investigation.

Detection of hemodynamic adaptations during impending syncope: Implementation of a robust algorithm based on pulse arrival time measurements only

Syncopes are a major public health concern since they can cause severe injuries e.g. by associated falls. We previously demonstrated the feasibility of syncope prediction based on the pulse arrival time (PAT) analysis. Importantly, algorithms for early detection of impending syncope need to be robust against measurement noise, in particular photoplethysmography (PPG) artifacts, causing false detection. We introduce in this work an algorithm concept to deal with artifacts as well as to detect the onset of syncope based on tracking of relative PAT changes only. Our method has been shown useful to improve detection performance for measurements during impending syncope in patients undergoing head-up tilt table testing which might improve syncope prediction.

Improvement of Left Ventricular Function under Cardiac Resynchronization Therapy Goes along with a Reduced Incidence of Ventricular Arrhythmia

Objectives The beneficial effects of cardiac resynchronization therapy (CRT) are thought to result from favorable left ventricular (LV) reverse remodeling, however CRT is only successful in about 70% of patients. Whether response to CRT is associated with a decrease in ventricular arrhythmias (VA) is still discussed controversially. Therefore, we investigated the incidence of VA in CRT responders in comparison with non-responders. Methods In this nonrandomized, two-center, observational study patients with moderate-to-severe heart failure, LV ejection fraction (LVEF) ≤35%, and QRS duration >120 ms undergoing CRT were included. After 6 months patients were classified as CRT responders or non-responders. Incidence of VA was compared between both groups by Kaplan-Meier analysis and Cox regression analysis. ROC analysis was performed to determine the aptitude of LVEF cut-off values to predict VA. Results In total 126 consecutive patients (64±11years; 67%male) were included, 74 were classified as responders and 52 as non-responders. While the mean LVEF at baseline was comparable in both groups (25±7% vs. 24±8%; P = 0.4583) only the responder group showed an improvement of LVEF (36±6% vs. 24±7; p<0.0001) under CRT. In total in 56 patients VA were observed during a mean follow-up of 28±14 months, with CRT responders experiencing fewer VA than non-responders (35% vs. 58%, p<0.0061). Secondary preventive CRT implantation was associated with a higher likelihood of VA. As determined by ROC analysis an increase of LVEF by >7% was found to be a predictor of a significantly lower incidence of VA (AUC = 0.606). Conclusions Improvement of left ventricular function under cardiac resynchronization therapy goes along with a reduced incidence of ventricular arrhythmia.

Substrate characterization and catheter ablation in patients with scar-related ventricular tachycardia using ultra high-density 3-D mapping

Ablation of scar‐related ventricular tachycardia (VT), especially in noninducible VT or hemodynamically unstable patients, can be challenging. Thus, we evaluated feasibility of an ultra high‐density 3‐D mapping approach to characterize the ventricular substrate and, if possible, to map VT.

Reduction of Radiation Exposure in Atrial Fibrillation Ablation Using a New Image Integration Module: A Prospective Randomized Trial in Patients Undergoing Pulmonary Vein Isolation

Recently, a new image integration module (IIM, CartoUnivu™ Module) has been introduced to combine and merge fluoroscopy images with 3‐dimensional‐(3D)‐electroanatomical maps (Carto® 3 System) into an accurate 3D view. The aim of the study was to investigate the influence of IIM on the fluoroscopy exposure during pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (PAF) in a prospective randomized trial.