Standard Radiofrequency Research Articles

Impact of computed tomography image and contact force technology on catheter ablation for atrial fibrillation

To investigate the impact of using computed tomography (CT) and contact force (CF) technology on recurrence of atrial tachyarrhythmia after atrial fibrillation (AF) ablation. This non-randomized study included 2 groups of patients. All patients had symptomatic recurrent paroxysmal or persistent AF and were treated with at least 1 anti arrhythmic medication or intolerant to medication. The first group included 33 patients who underwent circumferential pulmonary veins isolation (PVI) for AF during 2012 and 2013 guided by CT image integration (Cartomerge, Biosense Webster, Diamond Bar, CA, United States) of left atrium and pulmonary veins into an electroanatomic mapping (EAM) system (CT group) using standard irrigated radiofrequency catheter (ThermoCool, Carto, Biosense Webster, Diamond Bar, CA, United States) or irrigated catheter with integrated CF sensor (Smart Touch, Carto, Biosense Webster, Diamond Bar, CA, United States). The second group included immediately preceding 32 patients who had circumferential PVI by standard irrigated catheter (ThermoCool) using only EAM (Carto) system (EAM group). Linear lesions were performed according to the discretion of operator. Sex, age, and persistent AF were not different between groups. PVI was achieved in all patients in both groups. Linear ablations including cavo-tricuspid isthmus and or roof line ablation were not different between groups. Free of atrial tachyarrhythmia during follow-up of 24 mo was significantly higher among CT group compared to EAM group (81% vs 55%; respectively; P = 0.027). When 11 patients from CT group who had ablation using Smart Touch catheter were excluded, the difference between CT group and EAM became non significant (73% vs 55%; respectively; P = 0.16). Sub analysis of CT group showed that patients who had ablation using Smart Touch catheter tend to be more free of atrial tachyarrhythmia compared to patients who had ablation using standard irrigated catheter during follow-up (100% vs 73%; respectively; P = 0.07). Major complications (pericardial effusion, cerebrovascular accident/transient ischemic attack, vascular access injury requiring intervention) did not occurred in both groups. These preliminary results suggest that CT image integration and CF technology may reduce the recurrence of atrial tachyarrhythmia after catheter ablation for AF.

Radiofrequency ablation for atrial fibrillation using only a bipolar device

Purpose: Although the maze procedure using a radiofrequency ablation device is a prevalent treatment for atrial fibrillation, a bipolar radiofrequency device is generally not used on the mitral and tricuspid annulus owing to the risk of coronary artery injury. We report the performance of the maze procedure using only a bipolar radiofrequency ablation device in our institute since 2009. Methods: We performed the maze procedure using only a bipolar device in 35 patients (bipolar group) and compared their operative outcomes with 56 patients who underwent standard radiofrequency ablation using bipolar and unipolar devices (standard group) for atrial fibrillation. Results: Preoperative characteristics were similar in the two groups. Operative data were also similar in the two groups except for a higher number of concomitant tricuspid valve repairs in the bipolar group (p = 0.007). There were no significant differences in mortality and morbidity between the two groups. Sinus rhythm was restored in a significantly higher number of patients in the bipolar group (71.4%) than in the standard group (39.3%; p = 0.002) at the first postdischarge follow-up. Conclusion: The maze procedure using only a bipolar radiofrequency device can be safely performed and results in a satisfactory sinus rhythm restoration.

EEG Radiotelemetry in Small Laboratory Rodents: A Powerful State-of-the Art Approach in Neuropsychiatric, Neurodegenerative, and Epilepsy Research.

EEG radiotelemetry plays an important role in the neurological characterization of transgenic mouse models of neuropsychiatric and neurodegenerative diseases as well as epilepsies providing valuable insights into underlying pathophysiological mechanisms and thereby facilitating the development of new translational approaches. We elaborate on the major advantages of nonrestraining EEG radiotelemetry in contrast to restraining procedures such as tethered systems or jacket systems containing recorders. Whereas a main disadvantage of the latter is their unphysiological, restraining character, telemetric EEG recording overcomes these disadvantages. It allows precise and highly sensitive measurement under various physiological and pathophysiological conditions. Here we present a detailed description of a straightforward successful, quick, and efficient technique for intraperitoneal as well as subcutaneous pouch implantation of a standard radiofrequency transmitter in mice and rats. We further present computerized 3D-stereotaxic placement of both epidural and deep intracerebral electrodes. Preoperative preparation of mice and rats, suitable anaesthesia, and postoperative treatment and pain management are described in detail. A special focus is on fields of application, technical and experimental pitfalls, and technical connections of commercially available radiotelemetry systems with other electrophysiological setups.

Hepatic Radiofrequency Ablation-induced Stimulation of Distant Tumor Growth Is Suppressed by c-Met Inhibition.

To elucidate how hepatic radiofrequency (RF) ablation affects distant extrahepatic tumor growth by means of two key molecular pathways. Rats were used in this institutional animal care and use committee-approved study. First, the effect of hepatic RF ablation on distant subcutaneous in situ R3230 and MATBIII breast tumors was evaluated. Animals were randomly assigned to standardized RF ablation, sham procedure, or no treatment. Tumor growth rate was measured for 3½ to 7 days. Then, tissue was harvested for Ki-67 proliferative indexes and CD34 microvascular density. Second, hepatic RF ablation was performed for hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), and c-Met receptor expression measurement in periablational rim, serum, and distant tumor 24 hours to 7 days after ablation. Third, hepatic RF ablation was combined with either a c-Met inhibitor (PHA-665752) or VEGF receptor inhibitor (semaxanib) and compared with sham or drug alone arms to assess distant tumor growth and growth factor levels. Finally, hepatic RF ablation was performed in rats with c-Met-negative R3230 tumors for comparison with the native c-Met-positive line. Tumor size and immunohistochemical quantification at day 0 and at sacrifice were compared with analysis of variance and the two-tailed Student t test. Tumor growth curves before and after treatment were analyzed with linear regression analysis to determine mean slopes of pre- and posttreatment growth curves on a per-tumor basis and were compared with analysis of variance and paired two-tailed t tests. After RF ablation of normal liver, distant R3230 tumors were substantially larger at 7 days compared with tumors treated with the sham procedure and untreated tumors, with higher growth rates and tumor cell proliferation. Similar findings were observed in MATBIII tumors. Hepatic RF ablation predominantly increased periablational and serum HGF and downstream distant tumor VEGF levels. Compared with RF ablation alone, RF ablation combined with adjuvant PHA-665752 or semaxanib reduced distant tumor growth, proliferation, and microvascular density. For c-Met-negative tumors, hepatic RF ablation did not increase distant tumor growth, proliferation, or microvascular density compared with sham treatment. RF ablation of normal liver can stimulate distant subcutaneous tumor growth mediated by HGF/c-Met pathway and VEGF activation. This effect was not observed in c-Met-negative tumors and can be blocked with adjuvant c-Met and VEGF inhibitors.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Pulmonary Vein Isolation Using the Visually Guided Laser Balloon: A Prospective, Multicenter, and Randomized Comparison to Standard Radiofrequency Ablation

BackgroundBalloon catheters have been designed to facilitate pulmonary vein (PV) isolation in patients with paroxysmal atrial fibrillation (AF). The visually guided laser balloon (VGLB) employs laser energy to ablate tissue under direct visual guidance. ObjectivesThis study compared the efficacy and safety of VGLB ablation with standard irrigated radiofrequency ablation (RFA) during catheter ablation of AF. MethodsPatients with drug-refractory paroxysmal AF were enrolled in a multicenter, randomized controlled study of PV isolation using either the VGLB or RFA (control). The primary efficacy endpoint was freedom from protocol-defined treatment failure at 12 months, including symptomatic AF occurring after the 90-day blanking period. The primary efficacy and safety endpoints were powered for noninferiority. ResultsA total of 353 patients (178 VGLB, 175 control) were randomized at 19 clinical sites. The mean procedure, ablation, and fluoroscopy times were longer with VGLB compared with controls. The primary efficacy endpoint was met in 61.1% in the VGLB group versus 61.7% in controls (absolute difference −0.6%; lower limit of 95% confidence interval [CI]: −9.3%; p = 0.003 for noninferiority). The primary adverse event rate was 11.8% in the VGLB group versus 14.5% in controls (absolute difference −2.8%; upper limit of 95% CI: 3.5; p = 0.002 for noninferiority), and was mainly driven by cardioversions. Diaphragmatic paralysis was higher (3.5% vs. 0.6%; p = 0.05), but PV stenosis was lower (0.0% vs. 2.9%; p = 0.03) with VGLB. ConclusionsDespite minimal prior experience, the safety and efficacy of VGLB ablation proved noninferior to RFA for the treatment of paroxysmal AF. (Pivotal Clinical Study of the CardioFocus Endoscopic Ablation System–Adaptive Contact [EAS-AC] [HeartLight] in Patients With Paroxysmal Atrial Fibrillation [PAF] [HeartLight]; NCT01456000)

Microendoscopy-guided percutaneous cordotomy for intractable pain: case series of 24 patients.

The aim of this study was to show that microendoscopic guidance using a double-channel technique could be safely applied during percutaneous cordotomy and provides clear real-time visualization of the spinal cord and surrounding structures during the entire procedure. Twenty-four adult patients with intractable cancer pain were treated by microendoscopic-guided percutaneous radiofrequency (RF) cordotomy using the double-channel technique under local anesthesia. A percutaneous lateral puncture was performed initially under fluoroscopy guidance to localize the target. When the subarachnoid space was reached by the guiding cannula, the endoscope was inserted for visualization of the spinal cord and surrounding structures. After target visualization, a second needle was inserted to guide the RF electrode. Cordotomy was performed by a standard RF method. The microendoscopic double-channel approach provided real-time visualization of the target in 91% of the cases. The other 9% of procedures were performed by the single-channel technique. Significant analgesia was achieved in over 90% of the cases. Two patients had transient ataxia that lasted for a few weeks until total recovery. The use of percutaneous microendoscopic cordotomy with the double-channel technique is useful for specific manipulations of the spinal cord. It provides real-time visualization of the RF probe, thereby adding a degree of safety to the procedure.

In vitro artefact assessment of a new MR-compatible microwave antenna and a standard MR-compatible radiofrequency ablation electrode for tumour ablation.

To evaluate and compare artefact configuration and diameters in a magnetic resonance (MR)-compatible prototype microwave (MW) applicator and a standard MR-compatible radiofrequency (RF) applicator for MR-guided tumour ablation. Both applicators were tested in a phantom study at 1.5T with three sequences: T1-weighted three-dimensional volume interpolated breath-hold examination (VIBE), T1-weighted fast low angle shot (FLASH), T2-weighted turbo spin echo (TSE). Applicator orientation to main magnetic field (B0) and slice orientation were varied. Needle tip location error (TLE) was assessed, and artefact diameters were calculated. Influence of imaging parameters on artefacts was assessed with analysis of variance (ANOVA) and post hoc testing. MW applicator: the shaft artefact diameter measured 2.3 +/- 0.8 mm. Tip artefact diameter and length measured 2.2 ± 0.8 mm and 2.4 ± 1.3 mm, respectively. A prominent oval artefact (diameter: 16.5 +/- 1.8 mm, length: 19.1 +/- 2.5 mm) appeared close to the tip. TLE: - .3 +/- 0.6 mm. RF applicator: shaft and tip diameter measured 8.9 +/- 4.7 mm and 9.0 +/- .0 mm, respectively. TLE: -0.1 +/- 0.8 mm. Minimal artefacts were measured with RF applicator orientation parallel to B0 (P < 0.0001), whereas no such influence was found for MW applicator. For both applicators, significantly large artefacts were measured with T1 FLASH (P = 0.03). The MW applicator's artefact is satisfactory and seems useable for MR-guided ablation procedures. MW applicator's artefact appearance is independent of angulation to main magnetic field. MW applicator's prominent distal artefact may increase visibility under MR-guidance. RF and MW applicator's artefacts are precise concerning tip depiction. Largest artefact diameters are measured with T1-weighted fast low angle shot sequence.

Quantification of N-Acetyl Aspartyl Glutamate in Human Brain using Proton Magnetic Resonance Spectroscopy at 7 T

UDC 543.422.25:611.81 The separation of N-acetyl aspartyl glutamate (NAAG) from N-acetyl aspartate (NAA) and other metabolites, such as glutamate, by in vivo proton magnetic resonance spectroscopy at 7 T is described. This method is based on the stimulated echo acquisition mode (STEAM), with short and long echo time (TE) and allows quantitative measurements of NAAG in the parietal and pregenual anterior cingulate cortex (pgACC) of human brain. Two base- sets for the LCModel have been established using nuclear magnetic resonance simulator software (NMR-SIM). Six healthy volunteers (age 25-35 years) have been examined at 7 T. It has been established that NAAG can be separated and quantifi ed in the parietal location and does not get quantifi ed in the pgACC location when using a short echo time, TE = 20 ms. On the other hand, by using a long echo time, TE = 74 ms, NAAG can be quantifi ed in pgACC structures. LCModel. Introduction. N-Acetylaspartylglutamic acid (NAAG) is a neuropeptide that is the third most prevalent neurotransmitter in the human brain (1). NAAG is produced by the coupling between a glutamic acid (Glu) and the N-acetylaspartic acid (NAA) via a peptide bond. Therefore, it may be diffi cult to distinguish between them on account of the similarity of the chemical structure. In human studies, it has been suggested that NAAG levels are abnormal in patients with schizophrenia (2) and decreased in amyotrophic lateral sclerosis (ALS) (3). In a previous study (4), it had been diffi cult to distinguish NAAG from NAA and Glu using proton magnetic resonance spectroscopy (MRS) at 3 T. As the dominant signal of the NAAG spectrum from the N-acetyl proton resonance peak is located at 2.05 ppm, which is 0.03 ppm away from the corresponding NAA signal at 2.02 ppm (5), a high resolution of metabolite peaks can be obtained using ultrahigh-fi eld strengths such as 7 T (6, 7) or at high fi elds (2 or 3 T), with unusual shimming (8). Proton magnetic resonance spectroscopy provides markers for various human brain diseases (9, 10). Some of the important measurement characteristics of the MRS technique are the signal-to-noise ratio (SNR), spatial and spectral resolution, as well as scan time; thus, several localization methods have been proposed. Single volume spectroscopy (SVS) localization techniques, with pulse sequences based on spin echoes (PRESS) (11) or stimulated echoes (STEAM) (12), provide the highest spectral quality (13), as the lower magnetic fi eld strengths result in a peak overlap of the human brain metabolites, such as, NAA with NAAG. Besides, standard spectroscopic sequences such as STEAM or PRESS will suffer if limited transmitter voltage takes place. This results in a reduced excitation flip angle and consequently insuffi cient excitation in the volume of interest (VOI). Moreover, previous studies have shown that the increase in magnetic field strength increases the 1 H NMR spectral peak separation and SNR and thus provides higher sensitivity when compared with lower field strengths (14, 15). With standard radio-frequency (RF) amplifiers and volume RF coils at 7 T, short 180° refocusing pulses are diffi cult to achieve in most parts of the brain. Therefore, earlier, high field MRS studies frequently employed surface coils with locally higher RF fi eld amplitude (16, 17). However, not all brain areas can be adequately examined using surface coils. As the goal of this study is to quantify the NAAG concentrations in different brain structures, STEAM with short echo time benefits, from reduced signal decay, because of the J-evolution of the coupled spin system, allows a more precise quantification of the metabolites, especially with a short T2 relaxation time (18). Thus, short echo times have been used in several studies (19). In the current study, echo time (TE) was selected to be short and long 20 and 74 ms, respectively. Although earlier studies had employed STEAM with ultrashort echo times (6 ms), they were limited by the surface coils that prevented detection in the deep brain regions (20). Also, a quadrature (transmit/receive) surface RF coil or a half-volume RF coil have been used for the

Radiofrequency Ablation: Inflammatory Changes in the Periablative Zone Can Induce Global Organ Effects, including Liver Regeneration.

To determine the kinetics of innate immune and hepatic response to the coagulation necrosis area that remains in situ after radiofrequency (RF) ablation, the cytokine profile of this response, and its local and global effect on the whole organ in a small-animal model. A standardized RF ablation dose (70°C for 5 minutes) was used to ablate more than 7% of the liver in 91 C57BL6 mice (wild type) according to a protocol approved by the animal care committee. The dynamic cellular response in the border zone surrounding ablation-induced coagulation and in the ablated lobe and an untreated lobe were characterized with immunohistochemistry 24 hours, 72 hours, 7 days, and 14 days after ablation (the time points at which cells migrate to necrotic tissues). After characterization of the cellular populations that reacted to the RF treatment, cytokines secreted by these cells were blocked, either by using interleukin-6 knockout mice (n = 24) or c-met inhibitor PHA 665752 (n = 15), to elucidate the key factors facilitating the wound healing response to RF ablation. Statistical significance was assessed with nonparametric analysis of variance. RF ablation induces a strong time-dependent immunologic response at the perimeter of the necrotic zone. This includes massive accumulation of neutrophils, activated myofibroblasts, and macrophages peaking at 24 hours, 7 days, and 14 days after ablation, respectively. In correlation with myofibroblast accumulation, RF ablation induced hepatocyte proliferation in both the ablated lobe and an untreated lobe (mean, 165.15 and 230.4 cyclin-dependent kinase 47-positive cells per ×20 field, respectively, at day 7; P < .02). Blockade of either IL-6 or c-met significantly reduced global hepatocyte proliferation (P < .05 for both), with the former reducing the accumulation of both macrophages and myofibroblasts surrounding the coagulation necrosis area (42.9 and 113.6 vs 7.3 and 46.6 macrophages and activated myofibroblasts per ×20 field, respectively; P < .036 for both). Hepatic RF ablation induces not only a local periablational inflammatory zone but also more global proliferative effects on the liver. These IL-6- and/or c-met-mediated changes could potentially account for some of the local and distant tumor recurrence observed after treatment.

Simulation of locating buried objects via fringe pattern-based measurements in an optical fiber sensor-integrated continuous-wave ground-penetrating radar system

A new ground-penetrating radar system that can determine the depth and position of a buried metal cylinder, which is the combination of an optical fiber sensor (OFS), continuous-wave transmitter, and optical communication link, is proposed and simulated in the MATLAB and Optiwave program packages. Employing an optical sensor instead of a standard radio frequency (RF) receiver offers the advantage of preventing electromagnetic interference along the sensor's main unit cable and lower amplification noise. In this paper, the electric field distribution at the OFS due to reflections from the soil surface and the buried object is obtained mathematically using Green's function. The OFS's detected electric signal is then simulated. The effects of the cylinder's depth and the RF transmitter frequency are observed. The plots of the OFS output voltages vs. the x-axis distance to the burial point display interference fringe patterns. The position and the depth of the cylinder are determined using the characteristics of these patterns. It is estimated that the burial depth can be ascertained with a maximum 5-cm error for a 1-GHz transmitter frequency.

Deposition and characterization of amorphous silicon with embedded nanocrystals and microcrystalline silicon for thin film solar cells

Amorphous silicon thin films with embedded nanocrystals and microcrystalline silicon were deposited by the standard Radio Frequency (RF) Plasma Enhanced Chemical Vapor Deposition (PECVD) technique, from SiH4, H2, Ar gas mixture at substrate temperature of 200°C. Two series of films were produced varying deposition parameters as chamber pressure and RF power density. The chemical bonding in the films was characterized by Fourier transform infrared spectroscopy, where it was observed a correlation between the hydrogen content and the morphological and electrical properties in the films. Electrical and optical parameters were extracted in both series of films, as room temperature conductivity (σRT), activation energy (Ea), and optical band gap (Eg). As well, structural analysis in the films was performed by Raman spectroscopy and Atomic Force Microscopy (AFM), which gives an indication of the films crystallinity. The photoconductivity changed in a range of 2 and 6 orders of magnitude from dark to AM 1.5 illumination conditions, which is of interest for thin film solar cells applications.

Design of parallel transmission radiofrequency pulses robust against respiration in cardiac MRI at 7 Tesla.

Two-spoke parallel transmission (pTX) radiofrequency (RF) pulses have been demonstrated in cardiac MRI at 7T. However, current pulse designs rely on a single set of B1(+)/B0 maps that may not be valid for subsequent scans acquired at another phase of the respiration cycle because of organ displacement. Such mismatches may yield severe excitation profile degradation. B1(+)/B0 maps were obtained, using 16 transmit channels at 7T, at three breath-hold positions: exhale, half-inhale, and inhale. Standard and robust RF pulses were designed using maps obtained at exhale only, and at multiple respiratory positions, respectively. Excitation patterns were analyzed for all positions using Bloch simulations. Flip-angle homogeneity was compared in vivo in cardiac CINE acquisitions. Standard one- and two-spoke pTX RF pulses are sensitive to breath-hold position, primarily due to B1(+) alterations, with high dependency on excitation trajectory for two spokes. In vivo excitation inhomogeneity varied from nRMSE = 8.2% (exhale) up to 32.5% (inhale) with the standard design; much more stable results were obtained with the robust design with nRMSE = 9.1% (exhale) and 10.6% (inhale). A new pTX RF pulse design robust against respiration induced variations of B1(+)/B0 maps is demonstrated and is expected to have a positive impact on cardiac MRI in breath-hold, free-breathing, and real-time acquisitions.

Different Surgical Approaches for Mesial Temporal Epilepsy: Resection Extent, Seizure, and Neuropsychological Outcomes

Background: Surgical therapy of intractable mesial temporal lobe epilepsy (MTLE) is an effective and well-established treatment. Objectives: We compared two different surgical approaches, standard microsurgical anterior temporal resection (ATL) and stereotactic radiofrequency amygdalohippocampectomy (SAHE) for MTLE, with respect to the extent of resection or destruction, clinical outcomes, and complications. Material and Methods: 75 MTLE patients were included: 41 treated by SAHE (11 right sided, 30 left sided) and 34 treated by ATL (21 right sided, 13 left sided). Results: SAHE and ATL seizure control were comparable (Engel I in 75.6 and 76.5% 2 years after surgery and 79.3 and 76.5% 5 years after procedures, respectively). The neuropsychological results of SAHE patients were better than in ATL. In SAHE patients, no memory deficit was found. Hippocampal (60.6 ± 18.7%) and amygdalar (50.3 ± 21.9%) volume reduction by SAHE was significantly lower than by ATL (86.0 ± 12.7% and 80.2 ± 20.9%, respectively). The overall rate of surgical nonsilent complications without permanent neurological deficit after ATL was 11.8%, and another 8.8% silent infarctions were found on MRI. The rate of clinically manifest complications after SAHE was 4.9%. The rate of visual field defects after SAHE was expectably less frequent than after ATL. Conclusion: Seizure control by SAHE was comparable to ATL. However, SAHE was safer with better neuropsychological results.

Low temperature hydrogenated microcrystalline silicon‐carbon alloys deposited by RF‐PECVD

AbstractTwo sets of hydrogenated microcrystalline silicon carbon alloys were deposited by standard radio frequency (RF) plasma enhanced chemical vapor deposition at a substrate temperature of 175 °C. The effect of the methane flow rate and of the RF‐power were investigated. Samples were deposited from a silane and methane gas mixture, highly diluted in hydrogen. The increase in methane flow rates leads to a decrease of the crystalline volume fraction and an increase in carbon incorporation. On the other hand, decreasing the RF‐power shifts the microcrystalline‐to‐amorphous transition at higher methane flow rates. Moreover, for similar amount of carbon incorporated, the decrease in RF‐power leads to materials showing higher crystalline volume fraction and average grains sizes. Both ion bombardment energy and carbon incorporation contributes to the microstructural properties of the deposited alloys. (© 2014 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

GW25-e1486 Application Research of ILR tracking of atrial fibrillation radiofrequency ablation treatment

Using ILR tracing atrial fibrillation patient who has been successfully accepted standard radiofrequency ablation. To evaluate the application value of ILR in the diagnosis and evaluation of curative effect in atrial fibrillation. Collected from May 2009 to August 2013, 25 cases of patients with

Guidelines for the Design and Optimization of Wireless Sensors Based on the Modulated Scattering Technique

This paper presents the guidelines for the development and optimization of wireless sensors based on the modulated scattering technique (MST). In particular, this paper is focused on the design and optimization of different MST tag prototypes with different modulation techniques. In addition, it is shown how to obtain the best performance of such sensors in terms of communication range and load efficiency. The preliminary measurements obtained with different experimental tag prototypes demonstrate that these MST sensors are able to measure and to correctly send data without an expensive radio frequency (RF) transmitter or a bulky wired connection. The results obtained show that such sensors could be an interesting alternative to standard RF identifier and wireless sensors.

CRT-609 Renal Denervation Using Standard 5F Radiofrequency Ablation Catheter in Patients with End Stage Renal Disease: A 6 Month Follow-Up

Renal denervation has been proven to be beneficial in treating resistant hypertension in patients with normal renal function. There are a significant number of end stage renal disease (ESRD) patients who have resistant hypertension despite being on multiple drugs and the benefits of RDN in such

Development of a Technique for Left Ventricular Endocardial Pacing via Puncture of the Interventricular Septum

Left ventricular (LV) pacing through the coronary sinus is the standard approach for cardiac resynchronization therapy. When this route is unavailable, the alternatives have major limitations. LV endocardial pacing through the interventriuclar septum may offer a simpler solution. We describe an initial case series to demonstrate technical feasibility and to describe our refinement of the puncture technique. Ten patients with previous failed coronary sinus lead implant or with nonresponse to cardiac resynchronization therapy and a suboptimal LV lead position were selected. All patients were anticoagulated. Left ventriculography and coronary angiography were performed to identify LV borders and septal vessels. Subclavian vein access was used for a superior approach ventricular transseptal puncture under fluoroscopic guidance, using a steerable sheath and a standard transseptal needle, radiofrequency needle, or radiofrequency energy delivered through a guidewire. An active-fixation pacing lead was successfully delivered to the endocardial wall of the lateral LV in all patients (9 men; age, 62±10 years). LV lead implant procedure time shortened with experience. The use of radiofrequency energy delivered through a guidewire was the most effective technique. Mean threshold and R wave at implant were 0.8±0.3 V and 10.8±3.9 mV. At follow-up (mean, 8.7 months; minimum, 0; and maximum 19), thresholds were stable, and there were no thromboembolic events. Of 9 patients, 8 were classed as clinical responders (1 had inadequate follow-up to assess response). LV endocardial pacing through a ventricular septal puncture is a feasible approach for cardiac resynchronization therapy.

Radiofrequency pulse design for the selective excitation of dissolved 129Xe

To optimize radiofrequency (RF) pulses for the selective excitation of dissolved phase (129)Xe that take into account the very short T2*, while simultaneously, minimally exciting the much larger gas signal. Numerical simulations of Shinnar le-Roux pulses and binomial coefficient composite-element pulses were performed and experimentally implemented on a 1.5 Tesla (T) clinical scanner. These were compared with pulses commonly used for short T2* imaging from the literature. The pulses were then experimentally tested in vivo with healthy volunteers inhaling hyperpolarized (129)Xe using nuclear MR spectroscopy on a 1.5T clinical scanner. Standard RF excitation pulses inadvertently excite the gas compartment, or are long enough that the T2* of the dissolved compartment deteriorates the received signal. Amplitude modulated binomial composite pulses perform well being short and having high selectivity, however, deteriorate at high amplifier gain setting. Composite pulses using pulse width modulation provide the desired frequency response even in these nonlinear, high gain regimes. Composite pulses provide a means of very narrow band frequency selectivity in a short duration pulse that is well suited to dissolved (129)Xe imaging. Pulse width modulation maintains the desired frequency response even in the presence of amplitude distortion.