G. Muqtada Chaudhry

Segmentation and registration of three-dimensional rotational angiogram on live fluoroscopy to guide atrial fibrillation ablation: A new online imaging tool

BACKGROUND Three-dimensional rotational atriography (3DATG) was developed to supplement two-dimensional fluoroscopy with 3D volume reconstruction of the left atrium (LA), pulmonary veins (PV), and other structures. Until recently, 3DATG images could only be viewed separately and were not suitable to directly guide atrial fibrillation (AF) ablation. OBJECTIVE The purpose of this study was to evaluate the feasibility and accuracy of intraprocedural 3DATG. METHODS Three-dimensional rotational atriography with right atrial contrast injection was obtained using a Philips Allura Xper FD10 system in 30 patients with symptomatic AF who also underwent preprocedural computed tomographic (CT) scan. RESULTS The majority (93%) of 3DATG image reconstructions were useful for guidance of catheter ablation. Nearly all PVs (94%), LA appendage (89%), and esophagus (100%) were successfully segmented. Measured PV ostial diameters compared using 3DATG and CT showed close concordance. Registration and re-registration of 3DATG overlay image was easily achieved with thoracic landmarks and validated by catheter placement demonstrating minimal discrepancy. Endoscopic views allowed for improved visualization of ostial position, dimensions, and navigation within the antrum. Lesion tagging on 3DATG overlay enhanced ablation guidance. Radiation exposure with 3DATG was significantly reduced compared with preprocedural CT scan (2.1 +/- 0.3 mSv vs 13.8 +/- 2.4 mSv, P <.001). CONCLUSION Intraprocedural 3DATG imaging during AF ablation with online segmentation and superimposition on live fluoroscopy is feasible. Overlay provides valuable and accurate information on 3D surface outline and endoscopic PV location. Three-dimensional rotational atriography overlay is a new imaging method with reduced radiation exposure that may replace preprocedural CT scan for catheter navigation and ablation of AF.

Prospective randomized comparison between the conventional electroanatomical system and three-dimensional rotational angiography during catheter ablation for atrial fibrillation

BACKGROUND Theoretically, the use of electroanatomical mapping systems may reduce radiation exposure, while three-dimensional rotational atriography (3DATG) may increase exposure. Anatomical representation and image registration using 3DATG are likely to be superior, but the net clinical benefit of either system is unknown. OBJECTIVE The purpose of this prospective randomized two-center study was to compare the procedural and clinical outcome of patients with atrial fibrillation (AF) treated by catheter ablation using either three-dimensional (3D) electroanatomical mapping (Carto) or 3DATG. METHODS From November 2007 to November 2008, 91 consecutive patients with AF (mean age 58 +/- 10 years; 63% paroxysmal AF, 37% persistent AF) from two centers (Bordeaux and Boston) were randomized to ablation using either 3DATG (44 patients) or Carto (47 patients). RESULTS Of the 47 left atrial shells acquired with 3DATG, one was uninterpretable. There was no difference in total radiofrequency applications (72 +/- 23 vs. 79 +/- 33 minutes, respectively, P = .296), procedural duration (232 +/- 65 vs. 218 +/- 67 minutes; P = .335), fluroroscopic duration (75 +/- 28 vs. 67 +/- 26 minutes; P = .151), or radiation exposure (71,810 +/- 42,954 vs. 68,009 +/- 38,345 mGy cm(2); P = .719) between procedures performed with 3DATG or Carto. After a mean follow-up of 10 +/- 4 months, there was no difference in clinical outcome using either Carto or 3DATG concerning total arrhythmia recurrence (34% versus 38%; P = .668) or AF recurrence (20% vs. 15%; P = .555). CONCLUSION Three-dimensional ATG-guided AF ablation has similar radiation exposure and procedural and outcome characteristics compared with Carto-guided ablation. The ease of use and accurate 3D representation of the left atrium make 3DATG a reasonable alternative to conventional 3D electroanatomical mapping systems, however, without advanced mapping functions.

Antiarrhythmic agents and proarrhythmia

The Vaughn Williams classification divides antiarrhythmic agents into four groups according to their effects on various ion channels. Class I agents block sodium channels and are subdivided into three groups. The use of class Ia agents is gradually on the decline, secondary to lack of a favorable risk/benefit ratio. Class Ib agents include lidocaine, which is extensively used for the acute treatment of ventricular tachyarrhythmias. Class Ic drugs are not advisable for patients with structural cardiac abnormalities secondary to a high risk of proarrhythmia. They are mainly used for supraventricular tachyarrhythmias. &bgr; blockers form class II. Class III agents, such as amiodarone and sotalol, prolong action potential duration and repolarization and are among the most widely used antiarrhythmics. They are the subject of active research, and newer agents are being developed. Calcium-channel blockers are grouped under class IV. Digoxin and adenosine have unique antiarrhythmic properties, which can be useful in the management of selected patients. All antiarrhythmic drugs have the potential to provoke arrhythmias and, therefore, should be used with caution. The risk of proarrhythmia is increased in patients with abnormal cardiac substrate, with electrolyte abnormalities, and during drug initiation. Correction of electrolyte imbalance and prevention of bradycardia while the drug is metabolized and/or excreted are the cornerstones of proarrhythmia management.

Evaluation of left atrial and posterior mediastinal anatomy by multidetector helical computed tomography imaging: Relevance to ablation

IntroductionIncreasing use of catheter ablation in the left atrium (LA) requires understanding of substrate anatomy, especially with regard to potential damage to adjacent structures.Methods and resultsWe reviewed multidetector helical computed tomography (MDCT) imaging on 42 subjects, 26 imaged before planned LA ablation for atrial fibrillation (AF), and 16 without AF. LA volume and dimensions were larger in patients with AF (p < 0.05) and the spine and aorta (Ao) impressed the LA more frequently in the AF group. The esophagus (Eo) was the predominant feature on the posterior LA wall, contacting it in all patients. The Ao was in contact with the LA body or the left inferior pulmonary vein (PV) in 32 (76%) of 42 cases, and in 10 it ran along an indentation on the posterior aspect of the LA. The coronary sinus was adjacent to LA ablation sites, the azygos vein was rarely adjacent to those sites, and the left bronchus abutted the PV ostium but not the LA. Two patients had findings that directly impacted the ablation procedure: one patient had a dilated fluid filled Eo with esophageal stricture and underwent nasogastric decompression before ablation, and one was discovered to have an anomalous PV and underwent surgical repair.ConclusionsMDCT imaging identifies structures adjacent to the LA, which could be affected by ablation. Posterior LA topography can be influenced by the position of the Ao or by the proximity of the spine. Preprocedural imaging can characterize anatomic structures that could be vulnerable during ablation, and detect unusual pathology that can affect the treatment plan.

Remote Surveillance of Implantable Cardiac Devices

The exponential growth of cardiac device implantation1,2 necessitates novel methods of surveillance with a view toward optimizing longterm device follow-up. In addition, the magnitude of recent pacemaker and implantable cardioverterdefibrillator (ICD) advisories demand a further increase in follow-up visits that raises the need for accurate monitoring of the integrity of implantable devices.3 Recent advances and innovations in telecommunications may offer an alternative to the current practice of device interrogation and may alleviate the burden of pacemakerdefibrillator clinics and provide considerable convenience for patients. Transtelephonic monitoring (TTM) of pacemakers has been used for many years; however, Internet-based remote surveillance systems of ICDs have been introduced only recently and are undergoing intense research and clinical evaluation.

Efficacy and tolerability of automatic nighttime atrial fibrillation shocks in patients with permanent internal atrial defibrillators

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Sheathless implantation of permanent coronary sinus-LV pacing leads.

Background: Implantation of CS‐LV pacing leads is usually accomplished through specialized sheaths with additional use of contrast venography and other steps. Direct implantation at a target pacing site could provide a simplified procedure with appropriate leads.

Two pacemaker systems in a patient with complete heart block: double trouble?

The most likely cause of a functioning pacemaker (PM) to fail delivering pacing stimuli is inhibition of the PM. This can be either due to internal malfunction of a pacing lead such as insulation break,1 physiologic stimuli, or external electromagnetic interference by various devices.2–5 There are some case reports of inhibition of ventricular pacing by a second abandoned PM.6 In a pacemaker-dependent patient, inhibition of the PM is potentially catastrophic and can lead to asystole and syncope.