Design and Development of a Novel Force-Sensing Robotic System for the Transseptal Puncture in Left Atrial Catheter Ablation

Transseptal puncture (TSP) is a prerequisite for left atrial catheter ablation for atrial fibrillation, requiring access from the right side of the heart. It is a demanding procedural step associated with complications, including inadvertent puncturing and application of large forces on the tissue wall. Robotic systems have shown great potential to overcome such challenges by introducing force-sensing capabilities and increased precision and localization accuracy. Therefore, this work introduces the design and development of a novel robotic system developed to perform TSP. We integrated optoelectronic sensors into the tools' fixtures, measuring tissue contact and puncture forces along one axis. The novelty of this design is in the system's ability to manipulate a Brockenbrough (BRK) needle and dilator-sheath simultaneously and measure tissue contact and puncture forces. In performing puncture experiments on anthropomorphic tissue models, an average puncture force of 3.97 ± 0.45 N (1SD) was established - similar to the force reported in literature on the manual procedure. This research highlights the potential for improving patient safety by enforcing force constraints, paving the way to more automated and safer TSP

Rapid automatic segmentation of abnormal tissue in late gadolinium enhancement cardiovascular magnetic resonance images for improved management of long-standing persistent atrial fibrillation

Background: Atrial fibrillation (AF) is the most common heart rhythm disorder. In order for late Gd enhancement cardiovascular magnetic resonance (LGE CMR) to ameliorate the AF management, the ready availability of the accurate enhancement segmentation is required. However, the computer-aided segmentation of enhancement in LGE CMR of AF is still an open question. Additionally, the number of centres that have reported successful application of LGE CMR to guide clinical AF strategies remains low, while the debate on LGE CMR’s diagnostic ability for AF still holds. The aim of this study is to propose a method that reliably distinguishes enhanced (abnormal) from non-enhanced (healthy) tissue within the left atrial wall of (pre-ablation and 3 months post-ablation) LGE CMR data-sets from long-standing persistent AF patients studied at our centre. Methods: Enhancement segmentation was achieved by employing thresholds benchmarked against the statistics of the whole left atrial blood-pool (LABP). The test-set cross-validation mechanism was applied to determine the input feature representation and algorithm that best predict enhancement threshold levels. Results: Global normalized intensity threshold levels T PRE = 1 1/4 and T POST = 1 5/8 were found to segment enhancement in data-sets acquired pre-ablation and at 3 months post-ablation, respectively. The segmentation results were corroborated by using visual inspection of LGE CMR brightness levels and one endocardial bipolar voltage map. The measured extent of pre-ablation fibrosis fell within the normal range for the specific arrhythmia phenotype. 3D volume renderings of segmented post-ablation enhancement emulated the expected ablation lesion patterns. By comparing our technique with other related approaches that proposed different threshold levels (although they also relied on reference regions from within the LABP) for segmenting enhancement in LGE CMR data-sets of AF patients, we illustrated that the cut-off levels employed by other centres may not be usable for clinical studies performed in our centre. Conclusions: The proposed technique has great potential for successful employment in the AF management within our centre. It provides a highly desirable validation of the LGE CMR technique for AF studies. Inter-centre differences in the CMR acquisition protocol and image analysis strategy inevitably impede the selection of a universally optimal algorithm for segmentation of enhancement in AF studies

A randomized prospective mechanistic cardiac magnetic resonance study correlating catheter stability, late gadolinium enhancement and 3 year clinical outcomes in robotically assisted vs. standard catheter ablation.

To prospectively compare cardiac magnetic resonance late gadolinium enhancement (LGE) findings created by standard vs. robotically assisted catheter ablation lesions and correlate these with clinical outcomes.Forty paroxysmal atrial fibrillation patients (mean age 54 ± 13.8 years) undergoing first left atrial ablation were randomized to either robotic-assisted navigation (Hansen Sensei(®) X) or standard navigation. Pre-procedural, acute (24 h post-procedure) and late (beyond 3 months) scans were performed with LGE and T2W imaging sequences and percentage circumferential enhancement around the pulmonary vein (PV) antra were quantified. Baseline pre-procedural enhancements were similar in both groups. On acute imaging, mean % encirclements by LGE and T2W signal were 72% and 80% in the robotic group vs. 60% (P = 0.002) and 76%(P = 0.45) for standard ablation. On late imaging, the T2W signal resolved to baseline in both groups. Late gadolinium enhancement remained the predominant signal with 56% encirclement in the robotic group vs. 45% in the standard group (P = 0.04). At 6 months follow-up, arrhythmia-free patients had an almost similar mean LGE encirclement (robotic 64%, standard 60%, P = 0.45) but in recurrences, LGE was higher in the robotic group (43% vs. 30%, P = 0.001). At mean 3 years follow-up, 1.3 procedures were performed in the robotic group compared with 1.9 (P < 0.001) in the standard to achieve a success rate of 80% vs. 75%.Robotically assisted ablation results in greater LGE around the PV antrum. Effective lesions created through improved catheter stability and contact force during initial treatment may have a role in reducing subsequent re-do procedures

Male gender and chronic obstructive pulmonary disease predict a poor clinical response in patients undergoing cardiac resynchronisation therapy

International audienceAims: Current guidelines advocate cardiac resynchronization therapy (CRT) in patients with class III/ IV NYHA heart failure, depressed left ventricular function and a broad QRS. However, a significant proportion of patients do not derive any benefit from CRT. The aim of this study was to identify clinical, electrocardiographic and echocardiographic predictors of response to CRT. Methods: A retrospective analysis of patients undergoing CRT in our institution was performed. A favourable clinical response to CRT was defined as an improvement in NYHA Heart failure class of ≥1 and lack of hospitalization with heart failure. Comparisons were made between responders and non-responders in terms of baseline characteristics and potential predictors of CRT response (QRS width, presence of LBBB, atrial fibrillation, evidence of mechanical dyssynchrony on echocardiography and LV lead position). Results: 164 patients had full follow up data. The mean follow up was 293 days. Of patient undergoing CRT, 90 (58.9%) had a favourable clinical response to CRT. Predictors of a lack of clinical response to CRT were male sex (p=0.012),and COPD (0.008). Pre-implant echocardiographic dyssynchrony assessment appeared not to predict response to CRT (p=0.87), however there was a trend in a positive response in those patients with significant dyssynchrony (p=0.09) defined as interventricular delay >40ms or maximal LV delay of >80ms. Conclusion: Male sex and the presence of COPD were shown to be independent predictors of non-response to CRT in this cohort of patients fulfilling current criteria for CRT

SPATIAL COMPOUNDING OF TRANS-ESOPHAGEAL ECHO VOLUMES USING X-RAY PROBE TRACKING

International audienceThe use of ultrasound imaging for image guidance of cardiac procedures is limited by the small field of view of the ultrasound volume. A larger view can be created by image-based registration of partially overlapping volumes, but automatic registration often fails unless the volume alignment is initialised close to the volumes' correct alignment. In this paper, we use X-ray images to track a trans-esophageal probe, which provides the required position estimates for the ultrasound volumes. The tracking is possible using multiple X-rays or just one X-ray at each probe position. We test the method in a phantom experiment and find that with at least 50% volume overlap, 98% of ultrasound volume pairs are correctly registered when tracked using three X-rays per volume, and 95% using single X-rays

Statistical model of paroxysmal atrial fibrillation catheter ablation targets for pulmonary vein isolation

Atrial fibrillation (AF) is the most common cardiac arrhythmia. Pulmonary vein isolation (PVI) by catheter ablation is a cornerstone treatment of paroxysmal AF. Low success rates are mainly due to reconnecting tissue. Local myocardial wall-thickness (WT) information is missing; lesion transmurality is impossible to estimate. WT information can be obtained from pencil beam high-resolution MRI, a time-consuming protocol. To reduce scan time, automatic selection of regions of interest is proposed. We developed a left atrial target probability model for paroxysmal AF ablation, based on intraprocedural ablation targeting data of fifteen patients, to support the selection of these regions. A common mesh serves as a reference for registration of the electroanatomical meshes and ablation targets using landmark registration and the Iterative Closest Points algorithm. This is followed by projection of the ablation targets onto the mean mesh model, closure of isolated ablation voids on the surface and Gaussian smoothing of the probability distribution. The final probability distribution clearly shows PVI contours as suggested in the consensus statement by European associations. The right inferior pulmonary vein (RIPV) shows a lower ablation probability, which may be due to limited maneuverability of the ablation catheter and the proximity of the RIPV ostium and the transseptal puncture, where the catheter enters the left atrium