A 10-Fr ultrasound catheter with integrated micromotor for 4-D intracardiac echocardiography

Image Integration Using Intracardiac Echography and Three-dimensional Reconstruction for Mapping and Ablation of Atrial and Ventricular Arrhythmias

This article reviews the basis for image integration of intracardiac echocardiography (ICE) with three-dimensional electroanatomic mapping systems and preprocedural cardiac imaging modalities to enhance anatomic understanding and improve guidance for atrial and ventricular ablation procedures. It discusses the technical aspects of ICE-based integration and the clinical evidence for its use. In addition, it presents the current technical limitations and future directions for this technology. This article also includes figures and videos of clinical representative arrhythmia cases where the use of ICE is key to a safe and successful outcome.

3-D Ultrasound Imaging Using Helicoid Array Transducers

Real-time 3-D intracardiac echocardiography (ICE) can enable faster imaging of surfaces orthogonal to the transducer, such as the pulmonary vein (PV) antra and cardiac valve annuli. However, the requirement for a 2-D grid of individually wired elements makes a traditional matrix array challenging to implement within an intravenous catheter. Helicoid array transducers are linear array transducers twisted about their long axis, allowing imaging of different elevation slices using sub-apertures. In this work, we examined the 3-D imaging characteristics of helicoid array transducers through simulations using Field II software and experimental measurements. We report results for varying transducer parameters, such as twist rate and sub-aperture size. We also discuss design considerations for these imaging parameters as they pertain to volumetric imaging of the heart.

Procedural sedation and analgesia for percutaneous high-tech cardiac procedures

The interest in percutaneous high-tech cardiac procedures has increased in recent years together with its safety and efficacy. In fragile patients, procedural sedation and analgesia are used to perform most of the procedures. General anesthesia remains the technique of choice during the team learning curve and might be required in selected patients or in emergent situations. Despite the high costs of percutaneous high-tech cardiac procedures, the decrease in length of hospital stays, rate of intensive care admission and complications, balance the increase in devices costs. In fragile patients who undergo percutaneous high tech cardiac procedures, the primary role of the anesthesiologist is to prevent the need for postprocedural intensive care unit and complications rate. Starting from the experience of a large university third level hospital we identified the eight most commonly performed contemporary percutaneous high tech cardiac procedures (ventricular tachycardia and atrial fibrillation ablation, protected percutaneous coronary intervention, transcatheter aortic valve implantation, MitraClip® (Abbott Laboratories; Abbott Park, IL, USA), percutaneous patent foramen ovale closure, left atrial appendage closure, and dysfunctional lead extraction), discuss the role of procedural sedation and analgesia in this setting, and explore future perspectives.

4-D ICE: A 2-D Array Transducer With Integrated ASIC in a 10-Fr Catheter for Real-Time 3-D Intracardiac Echocardiography

We developed a 2.5 ×6.6 mm ² 2 -D array transducer with integrated transmit/receive application-specific integrated circuit (ASIC) for real-time 3-D intracardiac echocardiography (4-D ICE) applications. The ASIC and transducer design were optimized so that the high-voltage transmit, low-voltage time-gain control and preamp, subaperture beamformer, and digital control circuits for each transducer element all fit within the 0.019-mm ² area of the element. The transducer assembly was deployed in a 10-Fr (3.3-mm diameter) catheter, integrated with a GE Vivid E9 ultrasound imaging system, and evaluated in three preclinical studies. The 2-D image quality and imaging modes were comparable to commercial 2-D ICE catheters. The 4-D field of view was at least 90 ^° ×60 ^° ×8 cm and could be imaged at 30 vol/s, sufficient to visualize cardiac anatomy and other diagnostic and therapy catheters. 4-D ICE should significantly reduce X-ray fluoroscopy use and dose during electrophysiology ablation procedures. 4-D ICE may be able to replace transesophageal echocardiography (TEE), and the associated risks and costs of general anesthesia, for guidance of some structural heart procedures.

In vivo real-time 3-D intracardiac echo using PMUT arrays

Piezoelectric micromachined ultrasound transducer (PMUT) matrix arrays were fabricated containing novel through-silicon interconnects and integrated into intracardiac catheters for in vivo real-time 3-D imaging. PMUT arrays with rectangular apertures containing 256 and 512 active elements were fabricated and operated at 5 MHz. The arrays were bulk micromachined in silicon-on-insulator substrates, and contained flexural unimorph membranes comprising the device silicon, lead zirconate titanate (PZT), and electrode layers. Through-silicon interconnects were fabricated by depositing a thin-film conformal copper layer in the bulk micromachined via under each PMUT membrane and photolithographically patterning this copper layer on the back of the substrate to facilitate contact with the individually addressable matrix array elements. Cable assemblies containing insulated 45-AWG copper wires and a termination silicon substrate were thermocompression bonded to the PMUT substrate for signal wire interconnection to the PMUT array. Side-viewing 14-Fr catheters were fabricated and introduced through the femoral vein in an adult porcine model. Real-time 3-D images were acquired from the right atrium using a prototype ultrasound scanner. Full 60° × 60° volume sectors were obtained with penetration depth of 8 to 10 cm at frame rates of 26 to 31 volumes per second.

Ring array transducers for real-time 3-D imaging of an atrial septal occluder

We developed new miniature ring array transducers integrated into interventional device catheters such as used to deploy atrial septal occluders. Each ring array consisted of 55 elements operating near 5 MHz with interelement spacing of 0.20 mm. It was constructed on a flat piece of copper-clad polyimide and then wrapped around an 11 French O.D. catheter. We used a braided cabling technology from Tyco Electronics Corporation to connect the elements to the Volumetric Medical Imaging (VMI) real-time 3-D ultrasound scanner. Transducer performance yielded a -6 dB fractional bandwidth of 20% centered at 4.7 MHz without a matching layer vs. average bandwidth of 60% centered at 4.4 MHz with a matching layer. Real-time 3-D rendered images of an en face view of a Gore Helex septal occluder in a water tank showed a finer texture of the device surface from the ring array with the matching layer.