Ultrafast four-dimensional imaging of cardiac mechanical wave propagation with sparse optoacoustic sensing

Propagation of electromechanical waves in excitable heart muscles follows complex spatiotemporal patterns holding the key to understanding life-threatening arrhythmias and other cardiac conditions. Accurate volumetric mapping of cardiac wave propagation is currently hampered by fast heart motion, particularly in small model organisms. Here we demonstrate that ultrafast four-dimensional imaging of cardiac mechanical wave propagation in entire beating murine heart can be accomplished by sparse optoacoustic sensing with high contrast, ∼115-µm spatial and submillisecond temporal resolution. We extract accurate dispersion and phase velocity maps of the cardiac waves and reveal vortex-like patterns associated with mechanical phase singularities that occur during arrhythmic events induced via burst ventricular electric stimulation. The newly introduced cardiac mapping approach is a bold step toward deciphering the complex mechanisms underlying cardiac arrhythmias and enabling precise therapeutic interventions.

The improvement of cardiac multispiral computed tomography protocol for planning interventional arrhythmia management

Purpose. The study aimed at the comparison of computed tomography (СT) contrast enhancement (CE) protocols for optimal visualization of cardiac chambers, evaluation of their impact on results of non-invasive superficial cardiac mapping.Methods. The study included 93 patients with heart rhythm disorders in whom catheter ablation of arrhythmia was planned. Noninvasive cardiac mapping for arrhythmia localization was performed and included multichannel ECG-registration and CT with intravenous СE (1st group - monophasic (50 patients), 2nd group - split-bolus (18 patients), 3rd group - with pre-bolus (25 patients). Qualitative and quantitative (measurement of mean blood attenuation in four chambers, calculation of ventricular-myocardial [VM] contrast-to-noise ratio VM-LV и VM-RV for the left ventricle [LV] and right ventricle [RV], respectively) parameters were compared between the groups. Fusion of ECG and CT data was carried out a semi-automatic mode with a non-invasive imaging complex.Results. Regardless of CE technique, sufficient and homogeneous contrast attenuation was obtained for the left atrium (LA) and LV (mean blood attenuation in LA more than 278 HU, LV 250 HU, VM-LV 0,582). In most cases, the enhancement of the right heart was insufficient with the monophasic protocol; the average CT density was lower than 200 HU, VM-RV 0,256. The split-bolus protocol improved visualization of the right atrium (RA) and RV (blood density in RA 258HU, RV 227HU, VMRV 0,541); however, there was a heterogeneity of the RA cavity due to artifacts from the superior vena cava (VC) and unenhanced blood from the inferior VC. Pre-bolus administration increased the contrast ratio between RA myocardium and blood due to the improvement of blood CT density in the inferior VC (blood density 294 HU). The quality of RV CE was similar to 2nd group (blood density 264 HU, VM-RV 0,565).Conclusion. The split-bolus and with pre-bolus CE protocols improve visualization of the RV, supporting the high-level enhancement of the left heart. The protocol with a pre-bolus is preferable for exact differentiation of the right atrial endocardial contour.

A mixed-reality holographic viewing platform enabling interaction with 3D electroanatomical maps using the HoloLens

Introduction Three dimensional (3D) electroanatomical maps (EAMs) created during electrophysiology procedures are traditionally displayed on 2D monitors connected to mapping systems. This has limitations, such as the lack of interaction with EAMs, the need for another user to control them, and the size of EAM displayed, which is limited by the resolution of these monitors. To overcome these, we created a novel technology to display EAMs on a mixed reality (MR) platform. Methods We used the Microsoft® HoloLens to create this MR platform. Studies from patients who had already undergone catheter ablation for atrial fibrillation, where EAMs of the left atria had been generated using different mapping systems (CARTO®, Rhythmia™ and EnSite Precision™) were utilised. These EAMs consisting of 3D coordinates and annotations (e.g. voltage & activation times) were exported from the mapping system. EAMs were then compiled and transferred to the HoloLens using custom-developed functions on Unity©, Microsoft® C# and VisualStudio. Subsequently, feedback was obtained from 3 independent electrophysiologists on this technology. Results We successfully exported the EAMs generated on CARTO®, Rhythmia™ and EnSite Precision™ mapping systems as holograms on to the HoloLens (Figure). Positive feedback included themes such as 1) the ability to use hand gestures and voice commands to interact with EAMs independent of another user unlike traditional cardiac mapping systems 2) offering an interactive 3D holographic experience whilst preserving the operators' physical interaction in the cardiac catheter lab 3) the capacity to better appreciate 3D geometry of EAMs in comparison to 2D monitors. The challenge of wearing a headset during long procedures was perceived as a disadvantage. Conclusion This technology, which can be used with any mapping system, is currently optimised for offline display. Our software will be made available as an opensource teaching and simulation tool. Users will be able to explore EAMs for research, planning complex cases and immersive learning. The future directions will include extending this toolkit for real-time cardiac mapping with catheter localisation, and could potentially be translated to other cardiac imaging modalities. FUNDunding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): Cardiovascular diseases charitable fund (CDCF) at Guy's and St Thomas' NHS Foundation Trust. Process of creating Holograms of EAMs Voltage map of left atrium as a Hologram

Use of 3D mapping system for ablating an accessory pathway associated with coronary sinus diverticulum

Background This is a rare and challenging case of Wolff–Parkinson–White syndrome due to a posteroseptal accessory pathway located in the coronary sinus diverticulum. It is often difficult to precisely locate this type of accessory pathway, and the ablation procedure could be associated with collateral damage to the neighbouring coronary arteries. Case Presentation The patient was a 49-year-old female with Wolff–Parkinson–White syndrome who was referred for catheter ablation. She had had a previous unsuccessful attempt at ablation and had remained symptomatic despite drug therapy. The pre-procedural cardiac computed tomography scan revealed the presence of a diverticulum in the proximal coronary sinus. Using an advanced three-dimensional cardiac mapping system, the electroanatomic map of the diverticulum was created. The accessory pathway potential was identified within the diverticulum preceding the ventricular insertion. The accessory pathway was then successfully ablated using radiofrequency energy. Conclusion We have demonstrated that the advanced three-dimensional cardiac mapping system plays a very important role in guiding clinicians in order to precisely locate and safely ablate this type of challenging accessory pathway.

The improvement of cardiac multispiral computed tomography protocol for planning interventional arrhythmia management

Purpose. Comparison of computer tomography (СT) contrast enhancement (CE) protocols for optimal visualization of cardiac chamber, definition it’s influence on results of non-invasive superficial cardiac mapping.Materials and methods. The study included 93 patients with heart rhythm disorders who planned catheter ablation of arrhythmia. Noninvasive cardiac mapping was made for topical diagnostics. It includes multichannel ECG-registration and CT with intravenous СE (1st group monophasic (50 patients), 2nd group split-bolus (18 patients), 3rd group with pre-bolus (25 patients). Qualitative and quantitative (measurement of mean blood attenuation in four chambers, calculation of ventricular-myocardial contrast-to-noise ratio VM-LV и VM-RV for left ventricle (LV) and right ventricle (RV), respectively) parameters were compared between groups. Fusion of ECG and CT data was made semi-automatic with diagnostic complex «Amycard 01К».Results. Regardless of CE technique was noted sufficient and homogeneous contrast attenuation of left atrium (LA) and LV (mean blood attenuation in LA more than 278 HU, LV 250 HU, VM-LV 0,582). Enhancement of right heart was insufficient with monophasic protocol, in most cases the average CT density was lower than 200 HU, VM-RV 0,256. Split-bolus protocol improves visualization of right atrium (RA) and RV (blood density in RA 258HU, RV 227HU, VM-RV 0,541), however there was heterogeneity of RA cavity because of artifacts from superior vena cava (VC) and unenhanced blood from inferior inferior VC. Using of pre-bolus increases contrast ratio between RA myocardium and blood due to increasing CT density of blood in inferior VC (blood density 294 HU). Quality of right ventricle CE was similar to 2nd group (blood density 264 HU, VM-RV 0,565).Conclusion. CE protocols split-bolus and with pre-bolus improve visualization of right ventricle, supporting the high level enhancement of left heart. Protocol with pre-bolus is preferable for exact differentiation of right atrial endocardial contour.

A Man with Unexplained Cause of Rapid Regular Wide QRS Complex Tachycardia: An Unusual Case Report of Atrial Flutter

Objective: To report an unusual case of atrial flutter with 1:1 atrioventricular (AV) conduction with unclear precipitating factors. Case Report: A 67-year-old Thai male patient presented with diarrhea and palpitation. The electrocardiogram showed a rapid regular wide QRS complex tachycardia (WCT). The tachycardia was spontaneously slow down during saline infusion. The atrial flutter with 2:1 AV conduction was demonstrated. The diagnosis of regular WCT was atrial flutter with 1:1 AV conduction. The precipitating cause could not be identified. The catheter ablation was successfully performed under EnSite Precision Cardiac Mapping System. The atrial flutter was suddenly terminated during catheter ablation along cavotricuspid isthmus. The patient remained sinus rhythm after eight months. Conclusion: The present case was an unusual case of atrial flutter with 1:1 AV conduction with unclear precipitating factors. Although some possible causes were demonstrated, clear precipitating causes in the present patient should be investigated in the future. Keywords: Atrial flutter with 1:1 AV conduction, Catheter ablation, Regular wide QRS complex tachycardia, Supraventricular tachycardia, Ventricular tachycardia

Non-invasive electrophysiological cardiac mapping from development to practice

<p>In modern interventional arrhythmology, invasive endocardial mapping systems can eliminate arrhythmias with a high degree of efficiency. However, invasive mapping systems have several disadvantages, such as: the invasiveness of the method, which requires some preparation and has a number of limitations; the impossibility of simultaneous determination of electrophysiological processes occurring throughout the heart; the complexity of mapping when the arrhythmia focus is located in hard-to-reach anatomical structures; localization of the focus on the epicardial surface of the heart and occasional and difficult-to-induce arrhythmias during surgery.<br />In clinical practice, it became necessary to develop and implement systems for superficial non-invasive electrophysiological mapping of the heart. The main difference between superficial non-invasive electrophysiological mapping of the heart and other techniques is that after processing all the information, it is possible to receive a holistic picture of electrophysiological processes occurring throughout the heart in real time instead of receiving separately recorded signals and information from several chambers of the heart.<br />In this article, we describe the history of the development and implementation of superficial non-invasive electrophysiological cardiac mapping and the potential use of the diagnostic method in treating the various types of arrhythmias. A brief technique of carrying out this diagnostic method is described. Further directions regarding the development and improvement of this research method are also discussed, such as developing and improving the system for visualizing heart processes occurring in real time, improving the treatment of patients with cardiac arrhythmias, introducing non-invasive mapping of heart data into the systems used for invasive electroanatomical mapping of the heart and integrating the method with systems for non-invasive ablation.<br />The non-invasive mapping system of the heart is a modern progressive and constantly evolving diagnostic method that enables visualizing the electrophysiological processes occurring in the human heart with high accuracy in a non-invasive manner. To determine tactics of treatment, decide on an interventional approach and select the optimal technology at the preoperative stage for treating patients with various rhythm disturbances in their hearts.</p><p>Received 19 November 2020 г. Revised 9 December 2020 г. Accepted 14 December 2020 г.</p><p><strong>Funding:</strong> The work is supported by a grant of the Russian Science Foundation (project No. 19-15-00406).</p><p><strong>Conflict of interest:</strong> Authors declare no conflict of interest.</p>

Stability and performance of the EnSite Precision cardiac mapping system for electrophysiology mapping and ablation procedures: results from the EnSite Precision observational study

Background The EnSite Precision™ Cardiac Mapping System is a catheter navigation and mapping system capable of displaying the three-dimensional (3D) position of conventional and sensor enabled electrophysiology catheters, as well as displaying cardiac electrical activity as waveform traces and dynamic 3-D maps of cardiac chambers. Objective The EnSite Precision™ Observational Study was designed to quantify and characterize the use of the EnSite Precision™ Cardiac Mapping System for mapping and ablation of cardiac arrhythmias in a real-world environment and to evaluate procedural and subsequent clinical outcomes. Methods 1065 patients were enrolled at 38 centers in the U.S. and Canada between 2017–2018. Eligible subjects were adults undergoing a cardiac electrophysiology mapping and radiofrequency ablation procedures using the EnSite Precision™ System. Results Of 989 patients who completed the protocol, a geometry was created in 936 (94.7%). Most initial maps were created using Automap (n=545, 67.0%) or a combination of Automap and manually mapping (n=151, 18.6%). Median time to create an initial map was 9.0 min (IQR 5.0–15.0), with a median number of used mapping points per minute of 92.7 (IQR 30.0–192.0). During ablation, AutoMark was used in 817 (82.6%) of procedures. The most frequent metrics for lesion color were Impedance Drop or Impedance Drop Percent (45.5% combined), time (23.9%) and average force (14.2%). At Canadian sites where LSI was an option, it was used as the color metric in 87 (45.8%) of cases (10.6% overall). The EnSite System was stable throughout 79.7% (n=788 of 989) of procedures. Factors affecting stability were respiratory change (n=88 of 989, 8.9%), patient movement (n=73, 7.4%), CS Positional Reference dislodgement (n=32, 3.2%), and cardioversion (n=19, 1.9%). Conscious sedation was used in 189 (19.1%) of patients. Acute success was reached based on the pre-defined endpoints for the procedure in 97.4% (n=963) of cases. Conclusion In a real-world study analysis, the EnSite Precision™ mapping system was associated with a high prevalence of acute procedural success, low mapping times, and high system stability. Funding Acknowledgement Type of funding source: None