Intracardiac Echocardiography

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.     

Radiofrequency Transseptal Catheter Electrode Fracture

Transseptal puncture is performed using a long needle advanced from the femoral approach. A radiofrequency catheter has been developed that delivers a short burst of radiofrequency energy and creates a micro puncture in the interatrial septum. We describe a case in which the distal radiofrequency electrode broke and became embedded in the interatrial septum. (PACE 2010; 33:e57–e58)     

Transseptal Catheterization: Considerations and Caveats

Transseptal catheterization is used by interventional cardiologists to gain access in the left atrium. This technique was initially introduced for left‐sided pressure measurements and has been integrated in a variety of procedures including left atrial ablations and percutaneous mitral valvuloplasties. The establishment of catheter ablation of atrial fibrillation as an effective treatment strategy has brought transseptal catheterization back to the limelight. Technique refinements, introduction of adjunctive imaging tools, and enrichment of available technical equipment have simplified the procedure. In the present article we review the technique of transseptal catheterization, presenting tips and caveats that could be of value for safe and successful transseptal punctures. (PACE 2010; 33:231–242)     

A Safe,Simple Technique for Transseptal Catheterization

Transseptal catheterization is required for atrial fibrillation ablation and many ablations for atrial tachycardias, left atrial flutters, and accessory pathways. Using a Brockenbrough needle or other specialized device adds time, expense, and risk of potential complications such as atrial or aortic perforation, pericardial effusion, and tamponade to these procedures. We present a simple, low‐risk technique for transseptal catheterization.     

Catheter Ablation of Focal Atrial Tachycardia from the Aortic Cusp: The Role of Electroanatomic Mapping and Intracardiac Echocardiography

Catheter ablation of periatrioventricular (peri‐AV) nodal atrial tachycardias (AT) from the noncoronary aortic cusp (NCC) can be challenging due to the close proximity of the AV node In such cases, intracardiac echocardiography (ICE) together with three‐dimensional mapping system can be helpful in guiding the ablation catheter and in assessing the anatomic relationship of the aorta to the surrounding structures. We report two patients with AT originating near the AV node who underwent successful catheter ablation from the NCC. ICE proved useful in positioning the ablation catheter within the aortic cusps. Electroanatomic mapping enabled tagging the earliest activation site and renavigation back. (PACE 2013; 36:e19–e22)     

单纯心内超声介导房间隔穿刺术的实验研究

目的本实验采用最新的心内超声技术,研究单纯超声心动图介导经皮房间隔穿刺术的可能性。方法8条麻醉犬经右颈外静脉穿刺插入心内超声心动图探头,右股静脉穿刺行房间隔穿刺术。使用球囊导管扩张房间隔卵圆孔制造房间隔缺损。术中测量球囊的直径,房间隔缺损直径以及过隔血流。术后心脏行病理学检查与术中结果对照。结果在单纯超声心动图监测下所有犬均成功行房间隔穿刺并扩张制造房间隔缺损,平均手术时间为37±8.6min。心内超声心动图能够准确描述导管的位置以及与周围结构的关系,即时评价房间隔缺损的大小以及过隔血流。球囊直径为10.02±0.79cm,体外测量值12.41±0.02cm,P＜0.05。术中房间隔缺损大小(4.4±0.85cm)与术后病理(4.38±0.88cm)无显著性差异。结论采用心内超声心动图的方法单纯使用超声介导经皮房间隔穿刺术是可行的。     

Interatrial Septum Thickness and Difficulty with Transseptal Puncture during Redo Catheter Ablation of Atrial Fibrillation

Background: Patients undergoing catheter ablation for atrial fibrillation (AF) frequently require redo procedures, but there are no data reporting interatrial septum thickness (IAS) and difficulty during repeat transseptal puncture (TSP). Methods: Patients undergoing two separate AF ablation procedures had preprocedural fossa ovalis (FO) thickness measured using transesophageal echocardiography (TEE). “Difficult” TSP was defined by two observers as requiring excessive force, or conversion to TEE guidance. Results: The study comprised 42 patients (37 male) with mean ± SD age 55 ± 9 years. Mean FO thickness was significantly greater at the time of redo TSP (2.2 ± 1.6 mm vs 2.6 ± 1.5 mm at redo, P = 0.03); however, this finding was limited to those who underwent initial dual transseptal sheath procedures, FO thickness 2.0 ± 1.5 mm and 2.5 ± 1.4 mm for TEE 1 and 2, respectively (P = 0.048). There was a trend for more frequent difficult redo TSP procedures, 7/42 (17%; 95% confidence interval [CI] 8–31) redo, versus 4/42 (10%; 95% CI 3–23) first TSP. On univariate analysis, FO thickness was not predictive of TSP difficulty; the only predictor of difficult redo TSP was diabetes. Conclusions: IAS thickness at the FO increased following catheter ablation of AF, yet on subgroup analysis this was limited to initial procedures utilizing dual transseptal sheaths. There was a trend toward more frequent difficulty during redo TSP, yet this was not associated with FO thickening. Diabetes may predispose to difficulty during redo TSP; this finding requires confirmation in a larger study population.     

Linear Radiofrequency Microcatheter Ablation Guided by Phased Array Intracardiac Echocardiography Combined with Temperature Decay

Background: Fluoroscopy‐guided catheter placement is limited in its ability to determine electrode‐endocardial contact and involves radiation exposure. We hypothesized that (1) intracardiac echocardiography (ICE) would provide superior assessment of linear electrode contact compared to fluoroscopy and (2) slow temperature decay upon discontinuation of the radiofrequency current (time for temperature to fall 90% after a 10‐second test application of the radiofrequency current T90) would indicate optimal electrode‐myocardial contact. Methods: Sixty endocardial lesions were created in the atria and ventricles of six goats by simultaneous delivery of the radiofrequency current through two linear electrodes of a microcatheter with a central interelectrode thermocouple. Catheter placement was guided by fluoroscopy. A 7.5‐MHz ICE transducer in the right atrium or ventricle assessed electrode contact. T90 and previously reported parameters of electrode contact and lesion formation were recorded. Histomorphometry was performed on the lesions. Results: T90 was 4.27 ± 4.98 seconds. Lesion depth significantly correlated with ICE assessment of electrode contact (r = 0.56, P = 0.001); T90 upon radiofrequency current offset (r = 0.48, P = 0.008), impedance fall upon radiofrequency current onset (r = 0.37, P = 0.008), bipolar pacing threshold preablation (r =?0.56, P = 0.001), bipolar electrogram amplitude preablation (r = 0.43, P = 0.02), but not with fluoroscopic assessment of the electrode contact (r = 0.18, n.s.). For the prediction of achieving a lesion depth of >2 mm, a T90 of >4.0 seconds yielded a specificity of 86% and a sensitivity of 52%, ICE yielded a specificity and sensitivity of 58% and 68%, respectively, while the specificity and sensitivity of fluoroscopy were 26% and 68%, respectively. Both ICE and T90 provide additional clinical relevance during guidance of cardiac microcatheter ablation.     

Experimental Studies With a 9F Forward‐Looking Intracardiac Imaging and Ablation Catheter

Objective. The purpose of this study was to develop a high‐resolution, near‐field‐optimized 14‐MHz, 24‐element broad‐bandwidth forward‐looking array for integration on a steerable 9F electrophysiology (EP) catheter. Methods. Several generations of prototype imaging catheters with bidirectional steering, termed microlinear (ML), were built and tested as integrated catheter designs with EP sensing electrodes near the tip. The wide‐bandwidth ultrasound array was mounted on the very tip, equipped with an aperture of only 1.2 by 1.58 mm. The array pulse echo performance was fully simulated, and its construction offered shielding from ablation noise. Both ex vivo and in vivo imaging with a porcine animal model were performed. Results. The array pulse echo performance was concordant with Krimholtz‐Leedom‐Matthaei model simulation. Three generations of prototype devices were tested in the right atrium and ventricle in 4 acute pig studies for the following characteristics: (1) image quality, (2) anatomic identification, (3) visualization of other catheter devices, and (4) for a mechanism for stabilization when imaging ablation. The ML catheter is capable of both low‐artifact ablation imaging on a standard clinical imaging system and high–frame rate myocardial wall strain rate imaging for detecting changes in cardiac mechanics associated with ablation. Conclusions. The imaging resolution performance of this very small array device, together with its penetration beyond 2 cm, is excellent considering its very small array aperture. The forward‐looking intracardiac catheter has been adapted to work easily on an existing commercial imaging platform with very minor software modifications.     

Real-time Integration of Intracardiac Echocardiography and Electroanatomic Mapping in PVCs Arising from the LV Anterior Papillary Muscle

A 54-year-old woman with idiopathic premature ventricular contractions (PVCs) underwent electrophysiological testing. Three-dimensional (3D) geometries of the papillary muscles and chamber of the left ventricle (LV) were reconstructed using a CARTO-based 3D ultrasound imaging system (Biosense Webster Inc., Diamond Bar, CA, USA) during the PVCs. Activation mapping in the LV was then performed during the PVCs and the activation map revealed the earliest ventricular activation on the anterior papillary muscle. An irrigated radiofrequency current delivered at that site with guidance from that system eliminated the PVCs. This case may suggest that the guidance system may be feasible and useful for catheter ablation of PVCs arising from uncommon sites.     

Intercommissural Lead Placement into a Right Ventricular Coronary Sinus—Utility of Intracardiac Echo Guidance

Patients with congenital heart disease and prosthetic valves frequently present management dilemmas related to cardiac pacing and lead placement. Permanent pacing of the right ventricle across a bioprosthetic tricuspid valve presents discreet issues related to its potential for traumatic injury and subsequent prosthetic valve dysfunction. Coronary sinus (CS) lead placement is being used more frequently to avoid valvular dysfunction. We report an unusual case in which the CS ostium was located ventricular to the tricuspid prosthesis. Intracardiac echocardiography was used to position a CS lead between the commissures of the tricuspid prosthesis resulting in trivial regurgitation acutely and at 1‐year follow‐up. (PACE 2011; 34:e30–e32)     

声振葡萄糖心脏声学造影与CDFI对心内分流的对比研究

采用声振５０％葡萄糖对９７例存在心内分流的先天性心脏病患者行心脏声学造影检查，将负性造影区（ＮＣＡ）形成及造影剂右向左分流情况与彩色多普勒血流显像（ＣＤＦＩ）结果进行对比分析，ＣＤＦＩ检查结果分为三种：左向右分流；双向分流；分流不明显。在ＣＤＦＩ显示为左向右分流的６２例患者中，声学造影检查发现ＮＣＡ５０例；在ＣＤＦＩ显示为双向分流的２２例患者中发现ＮＣＡ９例；ＣＤＦＩ无明显分流者，ＮＣＡ均为阴性，后两种情况造影检查均发现右向左分流。表明：ＣＤＦＩ示左向右分流越明显，ＮＣＡ越易观察，无明显彩色分流时，ＮＣＡ为阴性，但此时声学造影剂右向左分流较明显，这是由于右心压力增高所致。     

Intracardiac Echocardiography-Guided Cardiac Resynchronization Therapy: Technique and Clinical Application

Background: We undertook a pilot investigation to evaluate the feasibility of a novel technique using intracardiac echocardiography (ICE) for intraoperative assessment of cardiac resynchronization therapy (CRT).
Methods: We evaluated ICE intraoperative imaging of left ventricular (LV) function and aortic valvular flow as well as safety of implementation. ICE was used to guide CRT system lead placement, assess impact of pacing modes, and optimization of device programming.
Results: Twenty-three patients underwent ICE imaging. ICE showed global hypokinesis in six patients, regional wall motion abnormality only in 10 patients, and both in seven patients. Optimized CRT modes included mean atrioventricular (AV) interval of 170 ms and interventricular timing using simultaneous right ventricular (RV)-LV pacing (five patients), LV pacing only (one patient), and sequential LV to RV stimulation (15 patients) or RV to LV stimulation (two patients). ICE-guided CRT acutely improved mean left ventricular ejection fraction (LVEF) from 24 ± 9% to 41 ± 1% (P < 0.00001). During follow-up of 3–24 (mean 11) months, New York Heart Association class improved in all patients from a mean of 3.2 ± 0.4 at implant to 1.6 ± 0.7 (P < 0.0001), with improvement of LVEF from 19 ± 7% to 34 ± 12% (P = 0.0001). Actuarial survival was 83% at 12 months.
Conclusions: (1) ICE imaging is reliable and safe for continuous intraoperative imaging of LV wall motion, and assesses baseline status and impact of CRT interventions. (2) Intraoperative ICE-guided CRT optimization resulted in an increase in LVEF acutely and consistent improvement in heart failure. (3) Sequential biventricular pacing and longer AV interval programming were more often used in ICE-guided CRT.