Intracardiac radiofrequency ablation in living swine guided by polarization-sensitive optical coherence tomography.

SIGNIFICANCE: Pulmonary vein isolation with catheter-based radiofrequency ablation (RFA) is carried out frequently to treat atrial fibrillation. However, RFA lesion creation is only guided by indirect information (e.g., temperature, impedance, and contact force), which may result in poor lesion quality (e.g., nontransmural) and can lead to reoccurrence or complications. AIM: The feasibility of guiding intracardiac RFA with an integrated polarization-sensitive optical coherence tomography (PSOCT)-RFA catheter in the right atria (RA) of living swine is demonstrated. APPROACH: In total, 12 sparse lesions were created in the RA of three living swine using an integrated PSOCT-RFA catheter with standard ablation protocol. PSOCT images were displayed in real time to guide catheter-tissue apposition. After experiments, post-processed PSOCT images were analyzed to assess lesion quality and were compared with triphenyltetrazolium chloride (TTC) lesion quality analysis. RESULTS: Five successful lesions identified with PSOCT images were all confirmed by TTC analysis. In two ablations, PSOCT imaging detected gas bubble formation, indicating overtreatment. Unsuccessful lesions observed with PSOCT imaging were confirmed by TTC analysis. CONCLUSIONS: The results demonstrate that the PSOCT-RFA catheter provides real-time feedback to guide catheter-tissue apposition, monitor lesion quality, and possibly help avoid complications due to overtreatment, which may enable more effective and safer RFA treatment.

Novel emerging therapies in atherosclerosis targeting lipid metabolism.

INTRODUCTION: Recent years have brought significant developments in lipid and atherosclerosis research. Although statins are a cornerstone in hyperlipidemia management, new non-statin therapies have had an impact. The reduction of low-density lipoprotein cholesterol (LDL-C) further translates into the lowering of cardiovascular mortality. Additionally, lipid research has progressed beyond LDL-C reduction and this has brought triglyceride (TG) and other apoprotein-B containing lipids into focus. AREAS COVERED: Inclisiran and pemafibrate, with expected approval soon, come under the spotlight. We discuss other therapeutics such as lomitapide, mipomersen, volanesorsen, and evinacumab and newly approved non-statin-based therapies such as ezetimibe, icosapent ethyl (IPE), and bempedoic acid. EXPERT OPINION: New options now exist for the prevention of atherosclerosis in patients that are not optimized on statin therapy. Multiple guidelines endorse ezetimibe, PCSK9 inhibitors, bempedoic, and IPE as add-on therapy. Recently approved bempedoic acid/ezetimibe combination might gain popularity among clinicians. Inclisiran and pemafibrate show promise in the reduction of LDL-C and TG, respectively, and results are pending in cardiovascular outcome trials. Combination strategies could improve outcomes, but the challenge will be balancing cost and selecting the correct patient population for each treatment modality to maximize benefit with the fewest medications.

An update on pharmacotherapies in diabetic dyslipidemia.

Hyperlipidemia plays a crucial role in the underlying pathogenesis of multiple cardiovascular diseases (CVD), including coronary artery disease, peripheral arterial disease, carotid stenosis, and heart failure. The risk of developing such diseases in the diabetic population is relatively high. Diabetes mellitus (DM) is an independent risk factor for premature atherosclerosis. The hallmark of DM dyslipidemia is a demonstrably high level of atherogenic triglyceride rich lipids including very low-density lipoprotein, chylomicrons, and small dense low-density lipoprotein (LDL). Moderate to high intensity statins, targeting LDL cholesterol reduction, remain the cornerstone in the management of this unique disorder. Many 'non-statin' drugs have recently been studied in the DM patients who were either on a 'maximally tolerated statin' or 'statin intolerant'. Ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are particularly important and were incorporated in the recent guidelines by the European Society of Cardiology, American College of Cardiology, American Heart Association, and American Diabetes Association. Icosapent Ethyl has garnered huge interest this year following publication of the REDUCE-IT trial. There are several newer hypolipidemic drugs, including Bempedoic acid, Inclisiran and RVX-208, that are in different phases of clinical trials. In this article, we review the underlying pathophysiology of DM dyslipidemia, existing guidelines related to its management, and the potential of newer hypolipidemic and anti-inflammatory drugs being incorporated in the management of DM.

Integrated RFA/PSOCT catheter for real-time guidance of cardiac radio-frequency ablation.

Radiofrequency ablation (RFA) is an important standard therapy for cardiac arrhythmias, but direct monitoring of tissue treatment is currently lacking. We demonstrate an RFA catheter integrated with polarization sensitive optical coherence tomography (PSOCT) for directly monitoring the RFA process in real time. The integrated RFA/OCT catheter was modified from a standard clinical RFA catheter and includes a miniature forward-viewing cone-scanning OCT probe. The PSOCT system was validated with a quarter-wave plate while the RFA function of the integrated catheter was validated by comparing lesion sizes with those made with an unmodified RFA catheter. Additionally, the integrated catheter guided catheter-tissue apposition and monitored RFA lesion formation in cardiac tissue in real time. The results show that catheter-tissue contact can be characterized by observing the features of the blood and tissue in the acquired OCT images and that RFA lesion formation can be confirmed by monitoring the change in phase retardance in the acquired PSOCT images. This system demonstrates the feasibility of an integrated RFA/OCT catheter to deliver RF energy and image the cardiac wall simultaneously and justifies further research into use of this technology to aid RFA therapy for cardiac arrhythmias.

Device localization and dynamic scan plane selection using a wireless magnetic resonance imaging detector array.

PURPOSE: A prototype wireless guidance device using single sideband amplitude modulation (SSB) is presented for a 1.5T magnetic resonance imaging system. METHODS: The device contained three fiducial markers each mounted to an independent receiver coil equipped with wireless SSB technology. Acquiring orthogonal projections of these markers determined the position and orientation of the device, which was used to define the scan plane for a subsequent image acquisition. Device localization and scan plane update required approximately 30 ms, so it could be interleaved with high temporal resolution imaging. Since the wireless device is used for localization and does not require full imaging capability, the design of the SSB wireless system was simplified by allowing an asynchronous clock between the transmitter and receiver. RESULTS: When coupled to a high readout bandwidth, the error caused by the lack of a shared frequency reference was quantified to be less than one pixel (0.78 mm) in the projection acquisitions. Image guidance with the prototype was demonstrated with a phantom where a needle was successfully guided to a target and contrast was delivered. CONCLUSION: The feasibility of active tracking with a wireless detector array is demonstrated. Wireless arrays could be incorporated into devices to assist in image-guided procedures.

Identification and mitigation of interference sources present in SSB-based wireless MRI receiver arrays.

PURPOSE: Single sideband amplitude modulation (SSB) is an appealing platform for highly parallel wireless MRI detector arrays because the spacing between channels is ideally limited only by the MRI signal bandwidth. However this assumes that no other sources of interference are present outside that bandwidth. This work investigates the practical interference between multiple SSB-encoded MRI signals. METHODS: Noise from coil preamplifiers and carrier bleed-through are identified as sources of interference. Two different SSB systems were designed for 1.5 T with different noise filtering properties. We show how the differences between the filtered noise profiles impact the received MR signal's dynamic range (DRsig ) and image signal-to-noise ratio through simulation, bench measurements, and phantom imaging experiments. RESULTS: When operating individually in the MR scanner, both SSB systems were shown to minimally impact the original DRsig and signal-to-noise ratio. Conversely, when all eight channels were operating simultaneously, an average signal-to-noise ratio loss was observed to be 12% in the one system, while a second system with more complex filtering was able to achieve a 3% loss in signal-to-noise ratio. CONCLUSION: Successful wireless transmission of multiple SSB-encoded MRI signals is possible as long as channel interference is properly managed through design and simulation.