Title: Image optimization and guidance for next generation wireless endocardial cardiac resynchronisation therapy.
Funder: Department of Health and Social Care

Abstract: The proposed project combines three technologies: image analysis, simulation and guidance to deliver a novel wireless endocardial pacing optimisation system. The technology developed in modules 1, 3 and 4 can also be readily adapted to conventional cardiac resynchronisation therapy (CRT) and/or future/alternate endocardial pacing systems. Module 1: Cardiac CT Image Processing System Patients eligible for endocardial pacing often have pre-implanted devices and are contraindicated for MRI. These patients can receive a contrast CT that provides high-resolution anatomical and functional images. We will extend our existing automatic segmentation workflow to the rib cage to facilitate transmitter location and orientation planning. We will implement and evaluate two proposed methods for ideniftying regions of myocardial scar [Thygesen2012] 1) Identify thin tissue regions indicative of scar 2) Measure regional motion to identify akinetic regions indicative of scar Module 2: Power Transmitter Location and Orientation Planner We will extend our current graphical user interface for planning procedures from MRI data [Shetty2013] to CT images. We will import the heart anatomy and rib cage segmentations. Standard ultrasound protocols will identify viable transmitter locations [Yeh2014]. The best viable transmitter location will then be determined based on the estimated coverage of the ventricle by the transmitter and the expected distance of the transmitter to the optimal pacing site. The transmitter location optimisation will be performed automatically and controls will be provided for manual tuning of the transmitter location and orientation. The transmitter location will be presented to the cardiac surgeon (Mr Blauth Co-I) prior to surgical implantation of the power transmitter. The location will then be confirmed from x-ray images during the catheter procedure. Module 3: Optimal Electrode Locator The optimal electrode position has been found to trend towards the latest activation region and to not be in scar [Shetty2013]. Scar maps from Module 1 will label regions that should not be paced. We will exploit biophysical models [Lee2016] of the spread of electrical activation in the heart, taking into consideration the patient anatomy and scar location, to predict the electrical synchrony achieved at all potential pacing locations. The optimal location will be automatically calculated to identify pacing sites that maximise predicted electrical synchrony from model simulations. Module 4: Overlay Guidance System Delivering optimal pre-procedural planning into actual treatment requires an effective real-time communication of the target electrode and transmitter position during procedures. CRT implant procedures are guided by x-ray fluoroscopy that can track the catheter locations in real time. Augmenting these images with the cardiac anatomy and scar during the procedure and indicating the target locations for the pacing electrode will translate pre-procedural planning into patient care. We will also introduce a real-time projection of the estimated power transmitter coverage that will be able to be overlaid on the x-ray fluoroscopy to allow adjustments of electrode placement based on the actual rather than the planned transducer location. Module 5: Testing and validation 20 patients will be recruited (consistent with patient numbers in previous successful overlay pilot studies [Shetty2013]). The best transmitter location and a target pacing site will be determined from CT images. During the implant, the overlay image displaying the target pacing site will be made available to the cardiologist. The acute haemodynamic response (AHR) (a measure of cardiac function) will be recorded at up to 10 locations, including the target location. The system will be evaluated by comparing the the highest AHR recorded against the AHR at the target location in each patient.

Lay abstract: Heart failure is a progressive and prevalent disease affecting 900,000 patients in the UK. Pacemaker-like, devices electrically activate or pace the heart through electrodes at the end of leads placed on the left and right-hand side of the heart and are one of the few effective treatments for heart failure. 7764 devices were implanted in 2013 in the UK, at ~&pound;4,600-15,900 per case and only 70% of patients receive a clinical benefit, costing the NHS an estimated &pound;48.3million per year. Currently, the lead on the left side of the heart is placed on the outer wall of the heart. We have shown that pacing the heart from the inside is more effective at improving cardiac function. New wireless pacing technology can electrically stimulate the heart from an electrode placed inside the heart and is expected to significantly improve the percentage of patients that benefit from this therapy. This new treatment poses specific challenges. Wireless electrodes can be placed anywhere on the inside of the heart, however, some pacing locations are significantly better than others and some can harm the patient. Wireless pacing also requires a power transmitter to be implanted that must be positioned relative to the wireless electrode to ensure effective power transmission and maximal battery life. Working with academic (KCL), clinical experts (GSTT), and imaging (Siemens) and device (EBR) companies, we will address these challenges by creating a planning and guidance system for wireless pacing. The planning system will identify the optimal location of the pacing electrode and power transmitter for each specific patient from pre-procedural medical images. The guidance system will augment medical images to present the optimal configuration to the clinician during the procedure. This will improve treatment success, leading to patient benefit and the adoption of this new and promising wireless technology.

Research activity codes: 5.4 SURGERY;6.4 SURGERY
Health categories: CARDIOVASCULAR