The use of intracardiac echocardiography and other intracardiac imaging tools to guide noncoronary cardiac interventions

A comparison of intracardiac echocardiography and transesophageal echocardiography for guiding device closure of ostium secundum atrial septal defect: A 15-year experience

BACKGROUND AND AIM

Our aim was to evaluate the fluoroscopy time (FT), procedure time (PT) safety and efficacy when using intracardiac echocardiography (ICE) in comparison to transesophageal echocardiography (TEE) guidance for transcatheter closure of Ostium Secundum Atrial Septal Defect (OS-ASD).

METHOD

Ninety patients (n = 90) diagnosed with OS-ASD underwent transcatheter closure between March 2006 and October 2021. Fifty-seven patients were treated under ICE guidance, while 33 patients were treated under TEE guidance.

RESULTS

Mean age was 43 ± 15 years and 42 ± 10 years in the ICE and TEE groups, respectively. The majority of patients had a centrally placed defect. Median FT was 8.40 min versus 11.70 min (p < .001) in the ICE group compared to the TEE group, respectively. Median PT was 43 min versus 94 min (p < .001) in the ICE group compared to the TEE group, respectively. Both ICE and TEE provided high quality images. All interventions were completed successfully, except for one patient in the ICE group who experienced a device migration, the development of atrial tachycardia in one patient and atrial fibrillation in two patients in the ICE group which spontaneously cardioverted. There were no other complications.

CONCLUSION

This study on a consistent cohort of patients with OS-ASD undergoing percutaneous closure suggests that use of ICE is safe and efficacious. Compared to TEE, ICE demonstrated significantly shorter FT and PT, decreasing the entire duration of the procedure and x-ray exposure. No relevant differences were observed in terms of success rate and complications.

Chinese expert consensus on the construction of the fluoroless cardiac electrophysiology laboratory and related techniques

Transcatheter radiofrequency ablation has been widely introduced for the treatment of tachyarrhythmias. The demand for catheter ablation continues to grow rapidly as the level of recommendation for catheter ablation. Traditional catheter ablation is performed under the guidance of X-rays. X-rays can help display the heart contour and catheter position, but the radiobiological effects caused by ionizing radiation and the occupational injuries worn caused by medical staff wearing heavy protective equipment cannot be ignored. Three-dimensional mapping system and intracardiac echocardiography can provide detailed anatomical and electrical information during cardiac electrophysiological study and ablation procedure, and can also greatly reduce or avoid the use of X-rays. In recent years, fluoroless catheter ablation technique has been well demonstrated for most arrhythmic diseases. Several centers have reported performing procedures in a purposefully designed fluoroless electrophysiology catheterization laboratory (EP Lab) without fixed digital subtraction angiography equipment. In view of the lack of relevant standardized configurations and operating procedures, this expert task force has written this consensus statement in combination with relevant research and experience from China and abroad, with the aim of providing guidance for hospitals (institutions) and physicians intending to build a fluoroless cardiac EP Lab, implement relevant technologies, promote the standardized construction of the fluoroless cardiac EP Lab.

Effects of a Mixed-Reality Headset on Procedural Outcomes in the Cardiac Catheterization Laboratory

BACKGROUND

Mixed reality head-mounted displays (MR-HMD) are a novel and emerging tool in healthcare. There is a paucity of data on the safety and efficacy of the use of MR-HMD in the cardiac catheterization laboratory (CCL). We sought to analyze and compare fluoroscopy time, procedure time, and complication rates with right heart catheterizations (RHCs) and coronary angiographies (CAs) performed with MR-HMD versus standard LCD medical displays.

METHODS

This is a non-randomized trial that included patients who underwent RHC and CA with MR-HMD between August 2019 and January 2020. Their outcomes were compared to a control group during the same time period. The primary endpoints were procedure time, fluoroscopy time, and dose area product (DAP). The secondary endpoints were contrast volume and intra and postprocedural complications rate.

RESULTS

50 patients were enrolled in the trial, 33 had a RHC done, and 29 had a diagnostic CA performed. They were compared to 232 patients in the control group. The use of MR-HMD was associated with a significantly lower procedure time (20 min (IQR 14-30) vs. 25 min (IQR 18-36), p = 0.038). There were no significant differences in median fluoroscopy time (1.5 min (IQR 0.7-4.9) in the study group vs. 1.3 min (IQR 0.8-3.1), p = 0.84) or median DAP (165.4 mGy·cm² (IQR 13-15,583) in the study group vs. 913 mGy·cm² (IQR 24-6291), p = 0.17). There was no significant increase in intra- or post-procedure complications.

CONCLUSION

MR-HMD use is safe and feasible and may decrease procedure time in the CCL.

Feasibility of a novel algorithm for automated reconstruction of the left atrial anatomy based on intracardiac echocardiography

BACKGROUND

Intracardiac echocardiography (ICE) is frequently used to guide electrophysiology procedures. The novel automated algorithm Cartosoundfam is a model-based algorithm which reconstructs a 3D anatomy of the left atrium (LA) based on a set of 2D intracardiac echocardiography (ICE) frames, without the need to manually annotate ultrasound (US) contours.

OBJECTIVE

The aim of this study was to determine the feasibility of the Cartosoundfam module in routine clinical setting.

METHODS

We included 16 patients undergoing LA mapping/catheter ablation. Two-dimensional US frames were acquired from the right atrium (RA) and the right ventricular outflow tract. The Cartosoundfam map was validated in two steps: (1) identification of anatomical structures (pulmonary veins [PV] and LA body and appendage) by alignment of the ablation catheter to the automated map; and (2) analysis of the automated lesion tags (Visitag) location in relation to the PV antrum of the Cartosoundfam map in nine patients with paroxysmal atrial fibrillation (AF) undergoing first time pulmonary vein isolation (PVI).

RESULTS

Mean 2D US frames per patient were 29 ± 6 and acquisition time was 16 ± 4 min. All anatomical structures were correctly identified in all patients (step 1). In the step 2 validation, the median distance to the map was 2.0 (IQR: 2.4) mm and the majority of the Visitags were classified as satisfactory (69%) but all PV segments had some Visitags classified as unsatisfactory.

CONCLUSION

The automated ICE-based algorithm correctly identified the LA anatomical structures in all patients with a 69% anatomical accuracy of the Visitags alignments to the PV antrum segments.

Dual-modality fibre optic probe for simultaneous ablation and ultrasound imaging

All-optical ultrasound (OpUS) is an emerging high resolution imaging paradigm utilising optical fibres. This allows both therapeutic and imaging modalities to be integrated into devices with dimensions small enough for minimally invasive surgical applications. Here we report a dual-modality fibre optic probe that synchronously performs laser ablation and real-time all-optical ultrasound imaging for ablation monitoring. The device comprises three optical fibres: one each for transmission and reception of ultrasound, and one for the delivery of laser light for ablation. The total device diameter is < 1 mm. Ablation monitoring was carried out on porcine liver and heart tissue ex vivo with ablation depth tracked using all-optical M-mode ultrasound imaging and lesion boundary identification using a segmentation algorithm. Ablation depths up to 2.1 mm were visualised with a good correspondence between the ultrasound depth measurements and visual inspection of the lesions using stereomicroscopy. This work demonstrates the potential for OpUS probes to guide minimally invasive ablation procedures in real time.

Circuits on miniaturized ultrasound imaging system-on-a-chip: a review

Trends of medical system move from a traditional in-person visit to virtual healthcare increases demands on point-of-care devices. Because ultrasound (US) is non-invasive, the demands highlight US imaging among other imaging modalities. Thanks to the development of US transducer technology, miniaturized US with application-specific integrated circuits (ASIC) have been researched. For example, applications that require small aperture sizes such as intravascular US (IVUS) and intra-cardiac echocardiography (ICE) require integration of system-on-a-chip (SoC) on the transducer. This paper reviews circuit techniques on the transmitter (TX) and receiver (RX) of the US imaging system. As TX circuits, pulser, T/RX switch, TX beamformer, and power management circuits are discussed. State-of-the-art transducer modeling, pre-amplifier, time-gain compensation, RX beamformer, quadrature sampler, and output driver are introduced as RX circuits.

Let there be light! The meteoric rise of cardiac imaging

Imaging plays a central role in modern cardiovascular practice. It is a field characterised by exciting technological advances that have shaped our understanding of pathology and led to major improvements in patient diagnosis and care. The UK has played a key international role in the development of this subspecialty and is the current home to many of the leading global centres in multimodality cardiovascular imaging. In this short review, we will outline some of the key contributions of the British Cardiovascular Society and its members to this rapidly evolving field and look at how this relationship may continue to shape future cardiovascular practice.

Radiofrequency ablation for treatment of atrial fibrillation with the use of intracardiac echocardiography vs without intracardiac echocardiography: A meta-analysis of observational and randomized studies

AIMS

Intracardiac echocardiography (ICE) provides superior quality images and can monitor catheter location within the heart continuously. Given the limited evidence, we conducted the meta-analysis to evaluate outcomes with ICE in radiofrequency (RF) ablation of atrial fibrillation (AF).

METHODS AND RESULTS

PubMed/MEDLINE, Embase and Cochrane were searched for studies reporting RF ablation for treatment of AF with the use of ICE vs without ICE and 12 studies were included. Sensitivity analyses limiting studies to ablation with the use of contact force (CF) catheters were conducted and subgroup analyses were performed according to the published year. In main analyses, RF ablation with ICE for treatment of AF was associated with significant reduction in total X-ray time (MD, -9.80; 95% CI, -15.57 to -4.04; I² =99%; p <0.01), total procedure time (MD, -17.65; 95% CI, -30.22 to -5.09; I² =89%; p <0.01), and complications (RR, 0.90; 95% CI, 0.87 to 0.92; I² =20%; p<0.01) vs without ICE. The ICE-guided group tended to decrease total absorbed X-ray dose (SMD, -0.91; 95% CI, -1.86 to 0.04; I² =96%; p =0.06). Freedom from arrhythmia (RR, 1.06; 95% CI, 0.98 to 1.14; I² =0%; p =0.13) was comparable between the two groups.

CONCLUSION

In patients with AF, ICE-guided RF ablation is correlated with significant reductions in total X-ray time, total procedure time, and complications vs ablation without ICE. Total absorbed X-ray dose tends to reduce in the ICE group and freedom from arrhythmia is comparable between the two groups. This article is protected by copyright. All rights reserved.

Use of a novel 4D intracardiac echocardiography catheter to guide interventional electrophysiology procedures

INTRODUCTION

Standard two-dimensional (2D), phased-array intracardiac echocardiography (ICE) is routinely used to guide interventional electrophysiology (EP) procedures. A novel four-dimensional (4D) ICE catheter (VeriSight Pro, Philips) can obtain 2D and three-dimensional (3D) volumetric images and cine-videos in real-time (4D). The purpose of this study was to determine the early feasibility and safety of this 4D ICE catheter during EP procedures.

METHODS

The 4D ICE catheter was placed from the femoral vein in ten patients into various cardiac chambers to guide EP procedures requiring transseptal catheterization, including ablation for atrial fibrillation and left atrial appendage closure. 2D- and 3D-ICE images were acquired in real-time by the electrophysiologist. A dedicated imaging expert performed digital steering to optimize and postprocess 4D images.

RESULTS

Eight patients underwent pulmonary vein isolation (cryoballoon in seven patients, pulsed field ablation in one, additional radiofrequency left atrial ablation in one). Two patients underwent left atrial appendage closure. High quality images of cardiac structures, transseptal catheterization equipment, guide sheaths, ablation tools, and closure devices were acquired with the ICE catheter tip positioned in the right atrium, left atrium, pulmonary vein, coronary sinus, right ventricle, and pulmonary artery. There were no complications.

CONCLUSION

This is the first experience of a novel deflectable 4D ICE catheter used to guide EP procedures. 4D ICE imaging is safe and allows for acquisition of high-quality 2D and 3D images in real-time. Further use of 4D ICE will be needed to determine its added value for each EP procedure type.

Value of echocardiography for mini-invasive per-atrial closure of perimembranous ventricular septal defect

The purpose of this study was to assess the value of echocardiography for intraoperative guidance during closure of perimembranous ventricular septal defects (pmVSD) and to assess outcomes of these patients. We identified and assessed 78 patients who underwent 2- and 3-dimensional echocardiography-guided mini-invasive per-atrial closure of pmVSD in the cardiac surgery department of our institution, from February 2016 to August 2018, and 76 patients who underwent transcatheter closure of VSD guided by fluoroscopy at the pediatric department (percutaneous control group). All the patients underwent echocardiography. Their clinical data were retrospectively reviewed and analyzed. All patients were followed up using transthoracic echocardiography (TTE) for a maximum of 24 months after the closure. All patients underwent successful device implantation. Echocardiography showed that the major immediate complications included residual shunt, pericardial effusion, and tricuspid regurgitation in the per-atrial group. During the mid-term follow-up period, TTE revealed that the most common complication was tricuspid regurgitation (non-preexisting). There were no cases of VSD recurrence, device displacement, valvular injury, malignant arrhythmias, hemolysis, or death. Moreover, according to the TTE data, the intracardiac structure of the patients were improved. Compared to the control group, the intracardiac manipulation time was shorter and the number of patients with residual shunts, redeployment of devices, or immediate new tricuspid regurgitations was fewer when using 2- and 3-dimensional echocardiography. However, the procedure time in the per-atrial group was slightly longer than that in the control group. Two- and 3-dimensional echocardiography are feasible monitoring tools during mini-invasive per-atrial VSD closure. The short- and mid-term follow-up showed satisfactory results compared to fluoroscopy.

The Ideal Cardiac Mapping System

Cardiac mapping has witnessed significant and unprecedented progress over more than a century. At present, several mapping/imaging technologies are commercially available, alone or in combination. This article briefly discusses the advantages and limitations (disadvantages) of each technique.

An augmented reality system for image guidance of transcatheter procedures for structural heart disease

The primary mode of visualization during transcatheter procedures for structrural heart disease is fluoroscopy, which suffers from low contrast and lacks any depth perception, thus limiting the ability of an interventionalist to position a catheter accurately. This paper describes a new image guidance system by utilizing augmented reality to provide a 3D visual environment and quantitative feedback of the catheter’s position within the heart of the patient. The real-time 3D position of the catheter is acquired via two fluoroscopic images taken at different angles, and a patient-specific 3D heart rendering is produced pre-operatively from a CT scan. The spine acts as a fiduciary land marker, allowing the position and orientation of the catheter within the heart to be fully registered. The automated registration method is based on Fourier transformation, and has a high success rate (100%), low registration error (0.42 mm), and clinically acceptable computational cost (1.22 second). The 3D renderings are displayed and updated on the augmented reality device (i.e., Microsoft HoloLens), which can provide pre-set views of various angles of the heart using voice-command. This new image-guidance system with augmented reality provides a better visualization to interventionalists and potentially assists them in understanding of complicated cases. Furthermore, this system coupled with the developed 3D printed models can serve as a training tool for the next generation of cardiac interventionalists.

Intra-procedural monitoring protocol using routine transthoracic echocardiography with backup trans-oesophageal probe in transcatheter aortic valve replacement: a single centre experience

Aim

The aim of this study is to describe our 9-year experience in transcatheter aortic valve replacement (TAVR) using transthoracic echocardiography (TTE) as a routine intra-procedural imaging modality with trans-oesophageal echocardiography (TEE) as a backup.

Methods and results

From January 2008 to December 2017, 1218 patients underwent transfemoral TAVR at our Institution. Except the first 20 cases, all procedures have been performed under conscious sedation, with fluoroscopic guidance and TTE imaging monitoring. Once the TTE resulted suboptimal for final result assessment or a complication was either suspected or identified on TTE, TEE evaluation was promptly performed under general anaesthesia. Only 24 (1.9%) cases required a switch to TEE: 6 cases for suboptimal TTE prosthetic valve leak (PVL) quantification; 12 cases for haemodynamic instability; 2 cases for pericardial effusion without haemodynamic instability; 4 cases for urgent TAVR. The 30-days and 1-year all-cause mortality were 2.1% and 10.2%, respectively. Cardiac mortality at 30-days and 1-year follow-up were 0.6% and 4.1%, respectively. Intra-procedural and pre-discharge TT evaluation showed good agreement for PVL quantification (k agreement: 0.827, P = 0.005).

Conclusion

TTE monitoring seems a reasonable imaging tool for TAVR intra-procedural monitoring without delay in diagnosis of complications and a reliable paravalvular leak assessment. However, TEE is undoubtedly essential in identifying the exact mechanism in most of the complications.

All-Optical Rotational Ultrasound Imaging

Miniaturised high-resolution imaging devices are valuable for guiding minimally invasive procedures such as vascular stent placements. Here, we present all-optical rotational B-mode pulse-echo ultrasound imaging. With this device, ultrasound transmission and reception are performed with light. The all-optical transducer in the probe comprised an optical fibre that delivered pulsed excitation light to an optical head at the distal end with a multi-walled carbon nanotube and polydimethylsiloxane composite coating. This coating was photoacoustically excited to generate a highly directional ultrasound beam perpendicular to the optical fibre axis. A concave Fabry-Pérot cavity at the distal end of an optical fibre, which was interrogated with a tuneable continuous-wave laser, served as an omnidirectional ultrasound receiver. The transmitted ultrasound had a -6 dB bandwidth of 31.3 MHz and a peak-to-peak pressure of 1.87 MPa, as measured at 1.5 mm from the probe. The receiver had a noise equivalent pressure <100 Pa over a 20 MHz bandwidth. With a maximum outer probe diameter of 1.25 mm, the probe provided imaging with an axial resolution better than 50 µm, and a real-time imaging rate of 5 frames per second. To investigate the capabilities of the probe, intraluminal imaging was performed in healthy swine carotid arteries. The results demonstrate that the all-optical probe is viable for clinical rotational ultrasound imaging.

A Reduced-Wire ICE Catheter ASIC With Tx Beamforming and Rx Time-Division Multiplexing

This paper presents a single chip reduced-wire active catheter application-specific integrated circuit (ASIC), equipped with programmable transmit (Tx) beamforming and receive (Rx) time-division multiplexing (TDM). The proposed front-end ASIC is designed for driving a 64-channel one-dimensional transducer array in intracardiac echocardiography (ICE) ultrasound catheters. The ASIC is implemented in 60 V 0.18-μm HV-BCD technology, integrating Tx beamformers with high voltage pulsers and Rx front end in the same chip, which occupies 2.6 × 11 mm2 that can fit in the catheter size of 9 F (<3 mm). The proposed system reduces the number of wires from >64 to only 22 by integrating Tx beamformer that is programmable using a single low-voltage differential signaling data line. In Rx mode, the system uses 8:1 TDM with direct digital demultiplexing providing raw channel data that enables dynamic Rx beamforming using individual array elements. This system has been successfully used for B-mode imaging on standard ultrasound phantom with 401 mW of average power consumption. The ASIC has a compact element pitch-matched layout, which is also compatible with capacitive micromachined ultrasound transducer on CMOS application. This system addresses cable number and dimensional restrictions in catheters to enable ICE imaging under magnetic resonance imaging by reducing radio frequency induced heating.

Transseptal Techniques for Emerging Structural Heart Interventions

The development of new transseptal transcatheter interventions for patients with structural heart disease is fueling increasing interest in transseptal puncture techniques. The authors review contemporary transseptal puncture indications and techniques and provide a step-by-step approach to challenging transseptal access and procedural complications.

A new mapping method to estimate exit sites of ventricular arrhythmias using intracardiac echocardiography and M-mode for catheter ablation

Background

Catheter ablation of premature ventricular complexes (PVCs) has been used as a curative therapy in many cases. Intracardiac ultrasound with a magnetic sensor probe has recently become available for catheter ablation. In this study, we assessed a new mapping method, contraction mapping, for determining the optimal ablation sites using intracardiac ultrasound and M-mode. This study sought to assess the accuracy of the new mapping method using intracardiac echocardiography.

Methods

Eighteen patients (10 males and eight females; mean age, 63±12 years) with 104 mapping points diagnosed as idiopathic PVCs were included in this study. At the mapping points, the time interval from the onset of the QRS to the onset of the contraction (QRS-c-time) and the local activation time were measured using M-mode with an intracardiac echo probe and using the conventional method. The correlation between the QRS-c-time and local activation time were studied.

Results

The QRS-c-time was significantly correlated with the local activation time (activation time=−66.8+0.882 * QRS-c-time, R2=0.728, p<0.0001).

Conclusions

Contraction mapping could help determine the local activation time without the delivery of a catheter to the mapping points.

Feasibility of multiplane microtransoesophageal echocardiographic guidance in structural heart disease transcatheter interventions in adults

Introduction

Structural heart interventions are guided by transoesophageal or intracardiac echocardiography (TEE/ICE). MicroTEE, developed for paediatric purposes, is smaller and therefore less invasive and traumatic, avoiding the need for general anaesthesia. We aimed to show feasibility of procedural guidance by comparing image quality of microTEE with standard TEE and ICE during adult transcatheter interventions, and assess the accuracy in obtaining left atrial appendage (LAA) measurements between the microTEE probe and standard TEE.

Methods and results

We prospectively included 49 patients (20 women, 64 ± 18 years). Intraprocedural images were obtained by using the microTEE probe and standard (2D and 3D) TEE (LAA closure, MitraClip implantation) or ICE (interatrial communication closure, transseptal puncture for left atrial ablation). Two echocardiographers independently assessed image quality from 1 (excellent) to 4 (poor) and performed LAA measurements. Use of microTEE was not related to significant discomfort. Image quality obtained with the microTEE probe was lower than with standard TEE (2 [1–2] vs. 1 [1–2]; p = 0.04) and comparable with ICE images (2 [1–2] vs. 2 [1–2], p = 0.13). MicroTEE showed a wider field of view than ICE. LAA measurements on images obtained by microTEE were strongly associated with standard TEE.

Conclusions

MicroTEE seems feasible for guidance during transcatheter heart interventions in adults. MicroTEE imaging offers a wider field of view than ICE, and its accuracy is comparable with TEE. In transcatheter interventions performed under conscious sedation, microTEE might be a viable and advantageous alternative to standard TEE or ICE.

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.

Imaging Techniques in Percutaneous Cardiac Structural Interventions: Atrial Septal Defect Closure and Left Atrial Appendage Occlusion

Because of advances in cardiac structural interventional procedures, imaging techniques are playing an increasingly important role. Imaging studies show sufficient anatomic detail of the heart structure to achieve an excellent outcome in interventional procedures. Up to 98% of atrial septal defects at the ostium secundum can be closed successfully with a percutaneous procedure. Candidates for this type of procedure can be identified through a systematic assessment of atrial septum anatomy, locating and measuring the size and shape of all defects, their rims, and the degree and direction of shunting. Three dimensional echocardiography has significantly improved anatomic assessments and the end result itself. In the future, when combined with other imaging techniques such as cardiac computed tomography and fluoroscopy, 3-dimensional echocardiography will be particularly useful for procedure guidance. Percutaneous closure of the left atrial appendage offers an alternative for treating patients with atrial fibrillation and contraindication for oral anticoagulants. In the future, the clinical focus may well turn to stroke prevention in selected patients. Percutaneous closure is effective and safe; device implantation is successful in 94% to 99% of procedures. However, the procedure requires an experienced cardiac structural interventional team. At present, 3-dimensional echocardiography is the most appropriate imaging technique to assess anatomy suitability, select device type and size, guide the procedure alongside fluoroscopy, and to follow-up the patient afterwards.

Extracting and analyzing ejection fraction values from electronic echocardiography reports in a large health maintenance organization

The left ventricular ejection fraction value is an important prognostic indicator of cardiovascular outcomes including morbidity and mortality and is often used clinically to indicate severity of heart disease. However, it is usually reported in free-text echocardiography reports. We developed and validated a computerized algorithm to extract ejection fraction values from echocardiography reports and applied the algorithm to a large volume of unstructured echocardiography reports between 1995 and 2011 in a large health maintenance organization. A total of 621,856 echocardiography reports with a description of ejection fraction values or systolic functions were identified, of which 70 percent contained numeric ejection fraction values and the rest (30%) were text descriptions explicitly indicating the systolic left ventricular function. The 12.1 percent (16.0% for male and 8.4% for female) of these extracted ejection fraction values are <45 percent. Validation conducted based on a random sample of 200 reports yielded 95.0 percent sensitivity and 96.9 percent positive predictive value.

The Utility of Intracardiac Echocardiography Following Melody™ Transcatheter Pulmonary Valve Implantation

The aim of this study was to determine the utility of intracardiac echocardiography (ICE) in assessing Melody™ transcatheter pulmonary valve (TPV) function immediately following valve implantation. ICE is used increasingly in percutaneous cardiac interventions. At our center, ICE is routinely utilized to evaluate valve function following Melody TPV implantation, but the utility of this practice remains unclear. A retrospective review of all Melody valves placed in the right ventricular outflow tract from April 2010 to September 2013 was performed. The clinical utility of ICE was described, along with the relationship between ICE data and traditional hemodynamic/angiographic data. ICE was performed in 54 cases and provided excellent Melody TPV visualization with no complications. ICE did not change clinical management but did provide supplemental information in two cases. In one case, angiography showed severe catheter-related Melody insufficiency. Subsequent ICE confirmed no insufficiency and prevented the need for additional angiography. In the second case, ICE allowed characterization of the mechanism of a residual gradient. ICE did not detect any clinically significant paravalvar leaks or valvar insufficiency not seen by angiography. The peak catheterization gradient was more closely approximated by the mean ICE gradient (median difference -7.4 % between measurements) than by the peak ICE gradient (median difference 58.3 %; p < 0.0001). ICE provides excellent and safe visualization following Melody TPV implantation but did not provide new clinical information impacting management in this series. Selective use of ICE in cases with more than expected valve insufficiency or larger than expected residual gradients may streamline use while maintaining optimal clinical outcomes.

Intracardiac echocardiography for guidance of transcatheter aortic valve implantation under monitored sedation: a solution to a dilemma?

Transcatheter aortic valve implantation (TAVI) has been established as a valuable alternative to surgical aortic valve replacement in patients deemed to have high or prohibitive perioperative risk. However, there are several technical constraints and procedural risks inherent to TAVI. These risks include annulus rupture, ventricular perforation, aortic dissection, coronary occlusion, and dislodgement or migration of the valve prosthesis to the aorta or the left ventricle (LV). Other complications may be related to inappropriate valve deployment and subsequent paravalvular leak. Most complications cannot be detected at an early stage without echocardiographic guidance. Although not addressed by current guidelines, some European centres have advocated a 'minimalist' approach with exclusively fluoroscopic and angiographic guidance. Transoesophageal echocardiography (TEE), including real-time three-dimensional (RT-3D) imaging, has been established as a standard approach for peri-interventional guidance of TAVI. However, TEE monitoring almost always necessitates general anaesthesia and endotracheal intubation. A potential alternative to TEE is intracardiac echocardiography (ICE) that may provide a solution to a common dilemma: the most important advantage of ICE being the compatibility with monitored anaesthesia care without endotracheal intubation. Other advantages of ICE include uninterrupted monitoring, no fluoroscopic interference, and precise Doppler-based assessment of pulmonary artery pressures. Limitations of ICE include the need for additional venous access, the learning curve associated with a new device, and potentially increased cost.

Broadband miniature optical ultrasound probe for high resolution vascular tissue imaging

An all-optical ultrasound probe for vascular tissue imaging was developed. Ultrasound was generated by pulsed laser illumination of a functionalized carbon nanotube composite coating on the end face of an optical fiber. Ultrasound was detected with a Fabry-Pérot (FP) cavity on the end face of an adjacent optical fiber. The probe diameter was < 0.84 mm and had an ultrasound bandwidth of ~20 MHz. The probe was translated across the tissue sample to create a virtual linear array of ultrasound transmit/receive elements. At a depth of 3.5 mm, the axial resolution was 64 µm and the lateral resolution was 88 µm, as measured with a carbon fiber target. Vascular tissues from swine were imaged ex vivo and good correspondence to histology was observed.

The use of intracardiac echocardiography during percutaneous pulmonary valve replacement

High-quality live imaging assessment of cardiac valves and cardiac anatomy is crucial for the success of catheter-based procedures. We present our experience using Intracardiac echocardiography (ICE) during transcatheter Percutaneous Pulmonary Valve replacement (tPVR).This is a retrospective study that included 35 patients who underwent tPVR between April 2008 and June 2012. Thirty-one of these patients had the procedure performed under continuous ICE guidance. Pre-procedure transthoracic echocardiography (TTE) was obtained in all patients. ICE was performed at baseline, during the procedure, and at the conclusion of the procedure. Comparisons between the pre-procedure TTE and baseline ICE data and between post-procedure ICE data and the following day TTE were performed. Total of 35 patients had tPVR during the above-mentioned time period. Twenty-one patients received the Edwards Sapien valve and 14 patients had the Melody valve. Thirty-one patients had the procedure performed under continuous ICE guidance. The mean Pre-TTE peak gradient (PG) and Pre-ICE-PG were 45.5 ± 20 vs 33 ± 13 mmHg (p < 0.001) and the mean Pre-TTE mean gradient (MG) and Pre-ICE-MG were 27.7 ± 13 vs 21 ± 18 mmHg (p < 0.001). The mean Post-TTE- PG and Post-ICE-PG were 24.3 ± 11 vs 15.3 ± 7 mmHg (p < 0.001) and the mean of the Post-TTE-MG and Post-ICE-MG were 14.2 ± 7 vs 8.4 ± 4 mmHg (p < 0.001). There was a good correlation between peak ICE and TTE gradient at baseline and after valve placement. For the degree of pulmonary regurgitation, there was no significant difference between TTE and ICE. ICE is an important modality to guide tPVR in patients with dysfunctional homograft valve between the right ventricle and pulmonary artery and should be used to assess valve function before, during and immediately after the procedure.

Intracardiac echocardiography: evolving use in interventional cardiology

Intracardiac echocardiography (ICE) uses a catheter-based steerable ultrasound probe that is passed into the right heart chambers to image intracardiac structures. The transducer can be variably positioned for optimal imaging: in the inferior vena cava to visualize the abdominal aorta; in the right atrium for the interatrial septum, aortic, mitral, and tricuspid valves, and pulmonary veins; or in the right ventricle for the left ventricular function, outflow tract, or pulmonary artery. Intracardiac echocardiography is primarily used for imaging during an invasive cardiac procedure using conscious sedation, when transthoracic image quality would likely be inadequate, and transesophageal imaging would require general anesthesia. Intracardiac echocardiography is generally well tolerated and provides adequate images and sufficient information for the procedure performed. In the cardiac catheterization laboratory, ICE is routinely used for patent foramen ovale, atrial septal defect, and ventricular septal defect closures, allowing adequate percutaneous placement of septal occluders. It is now being considered in the current era of transcatheter aortic valve implantation necessitating improved imaging approaches for accurate placement. It is also routinely used for trans-septal punctures during mitral valvuloplasty and, more recently, with the advent of left atrial appendage closure devices. This article provides a comprehensive review of the current technology for ICE and its growing applications in the realm of interventional cardiology.

A novel echocardiographic imaging technique, intracatheter echocardiography, to guide veno-venous extracorporeal membrane oxygenation cannulae placement in a validated ovine model

Background

Echocardiography plays a fundamental role in cannulae insertion and positioning for extracorporeal membrane oxygenation (ECMO). Optimal access and return cannulae orientation is required to prevent recirculation. The aim of this study was to compare a novel imaging technique, intracatheter echocardiography (iCATHe), with conventional intracardiac echocardiography (ICE) to guide placement of ECMO access and return venous cannulae.

Methods

Twenty sheep were commenced on veno-venous ECMO (VV ECMO). Access and return ECMO cannulae were positioned using an ICE-guided technique. Following the assessment of cannulae position, the ICE probe was then introduced inside the cannulae, noting location of the tip. After 24 h, the sheep were euthanized and cannulae position was determined at post mortem. The two-tailed McNemar test was used to compare iCATHe with ICE cannulae positioning.

Results

ICE and iCATHe imaging was possible in all 20 sheep commenced on ECMO. There was no significant difference between the two methods in assessing access cannula position (proportion correct for each 90%, incorrect 10%). However, there was a significant difference between ICE and iCATHe success rates for the return cannula (p = 0.001). Proportion correct for iCATHe and ICE was 80% and 15% respectively. iCATHe was 65% more successful (95% CI 27% to 75%) at predicting the placement of the return cannula. There were no complications related to the ICE or iCATHe imaging.

Conclusion

iCATHe is a safe and feasible imaging technique to guide real-time VV ECMO cannulae placement and improves accuracy of return cannula positioning compared to ICE.

Electronic supplementary material

The online version of this article (doi:10.1186/2197-425X-2-2) contains supplementary material, which is available to authorized users.

Contemporary echocardiographic guiding tools for device closure of interatrial communications

Periinterventional echocardiographic guidance is considered desirable in order to make interventional closure of interatrial communications safe and straight forward. Transesophageal echocardiography (TEE) including real-time three-dimensional (RT-3D) imaging, later complemented and in part replaced by intracardiac echocardiography (ICE), has become established as the standard approach to guide those procedures. Especially in atrial septal defect (ASD) closure, which tends to be more challenging than patent foramen ovale (PFO) closure, a certain risk of severe complications remains and may result from suboptimal device performance. Other complications may be related to discontinuous use of echocardiographic monitoring. Image fusion and RT-3D ICE are currently under clinical testing and might be suitable to facilitate spatial orientation. Nowadays, two-dimensional ICE is the method of choice for guiding percutaneous device closure, especially of ASDs and "complex" PFOs. Uninterrupted TEE under deep sedation is an alternative. In contrast, closure of "simple" PFOs will often require nothing but final confirmation of the result, and therefore, short echocardiographic viewing is sufficient in many cases.