Background Technical advances have improved the safety of cardiac implantable electronic device (CIED) insertion, but periprocedural complications persist. Despite ultrasound (US) guidance for vascular access being feasible and exhibiting shorter fluoroscopy times, it is not widely adopted for insertion of CIEDs. Thus, we studied the use of US for CIED insertion to (1) quantify the success rate of venous cannulation, (2) identify predictors of failed cannulation, and (3) quantify the rate of complications using US guidance. Methods We studied 166 consecutive patients who underwent US‐guided CIED implantation. Anatomic parameters of the axillary vein were measured. The primary outcome was success (group 1) or failure (group 2) to obtain vascular access utilizing US guidance. Secondary outcomes included pneumothorax and hematoma. Results Successful US‐guided cannulation occurred in 154 of 166 patients (93%). No patient had a pneumothorax. Hematoma occurred in 1 of 166 patients (0.01%). Group 2 exhibited higher male proportion at 11 of 12 (92%) compared with 94 of 154 (61%) in group 1 (P = .03), increased vein depth at 3.84 versus 2.85 cm (P = .003), more right‐sided implants (P = .03), higher weight at 104.6 versus 85.3 kg (P = .017), higher body mass index at 35.6 versus 29.2 kg/m2 (P = .049), and higher body surface area at 2.24 versus 1.99 m2 (P = .013). Other parameters were statistically nonsignificant. In multivariate analysis, vein depth remained significantly associated with failure. Conclusion Using US guidance for CIED implantation is successful in the vast majority (93%) of patients. Rare cases of unsuccessful cannulation were associated with right‐sided implants and increased venous depth.
Rational routes to synthetic porphyrins bearing distinct mesosubstituents have typically been implemented at modest scale (<1 g quantities). The A 3 B-porphyrin 5-(4-hydroxymethylphenyl)-10,15,20-tri-p-tolylporphinatozinc(II) (Zn-1) is required in multigram quantities for possible commercial use in information storage applications. The synthesis of Zn-1 has been carried out by reaction of 5-(4-hydroxymethylphenyl)dipyrromethane and the dicarbinol derived from 1,9-di-p-toluoyl-5-p-tolyldipyrromethane. Four improvements have been made to the steps leading to the dipyrromethane and dipyrromethane-dicarbinol: (i) use of 50 equiv of pyrrole in the condensation of an aldehyde to give the dipyrromethane (versus 100 equiv previously), (ii) 1,9-diacylation of a dipyrromethane using the hindered Grignard reagent 2,6-dimethylphenylmagnesium bromide and p-toluoyl chloride to give the 1,9-diacyl versus 1-acyl products in >10:1 ratio (versus 4:1 using EtMgBr), (iii) isolation of the dibutyltin complex of the 1,9-diacyldipyrromethane from the crude reaction mixture by direct crystallization using methanol/methyl tert-butyl ether (MTBE) (versus silica chromatography), and (iv) reduction of the dibutyltin complex of the 1,9-diacyldipyrromethane (250 mM) with ∼10-15 mol equiv of NaBH 4 (versus 25 mM and 40 mol equiv). The procedures have been carried out with no chromatography at large scale, affording the dipyrromethane (31, 59, or 79 g), the dibutyltin complex of a 1,9-diacyldipyrromethane (361 g), and reduction of the latter (45 g). The porphyrin-forming reaction has been performed (25 mM reactants at 50-mmol scale, or 10 mM at 64-mmol scale) in a two-step process of condensation and oxidation to give the free base porphyrin 1 in 3.7-or 5.8-g quantities. Metalation with zinc acetate afforded Zn-1, which was isolated by direct crystallization. Taken together, the various improvements facilitate synthesis of the target porphyrin Zn-1 and may have broad applicability.
Aims The response to premature atrial complexes (PACs) during tachycardia has been shown to differentiate atrioventricular nodal re-entrant tachycardia (AVNRT) from focal junctional tachycardia (JT). His refractory PAC (HrPACs) perturbing the next His (resetting with fusion) is diagnostic of AVNRT and such a late PAC fusing with the native beat cannot reset the focal source of JT. Early PAC advancing the immediate His with continuation of tachycardia suggests JT but can also occur in AVNRT due to simultaneous conduction through the AV nodal fast and slow pathways [two-for-one response (TFOR)]. The objective of this study was to evaluate the incidence and mechanism of TFOR after early premature atrial complexes (ePACs) during AVNRT and to differentiate it from the known response to ePACs during JT. Methods and results Typical AVNRT cases were diagnosed using standard criteria. We evaluated the responses to scanning PACs delivered during tachycardia in 100 patients undergoing AV node slow pathway modification for AVNRT. The responses to HrPACs and ePACs delivered from coronary sinus os or high right atrium were retrospectively reviewed. In 10 patients, ePACs advanced the immediate His with continuation of tachycardia. In all 10 cases, HrPACs advanced the next His, confirming AVNRT as the mechanism, and indicating a TFOR. Conclusion A TFOR can occur in a small number of patients during AVNRT and is therefore not diagnostic of JT. However, HrPACs always perturbed the next His in these cases, confirming the diagnosis of AVNRT and allowing for differentiation from JT.
Background: Esophageal thermal injury is a risk of ablation of the posterior left atrium despite various devices utilized to date. Objective: Evaluate the potential of a commercially-available esophageal cooling device to provide esophageal protection during left atrial catheter ablation. Methods: In this pilot study, we randomized 6 patients undergoing catheter ablation for atrial fibrillation. Three patients received standard of care for our site (use of a single-sensor temperature probe, with adjunct iced-water instillation for any temperature increases >1°C). Three patients received standard ablation after placement of the esophageal cooling device using a circulating water temperature of 4°C. All patients underwent transesophageal echocardiogram (TEE) and esophagogastroduodenoscopy (EGD) on the day prior to ablation followed by EGD on the day after. Results: In the 3 control patients, one had no evidence of esophageal mucosal damage, one had diffuse sloughing of the esophageal mucosa and multiple ulcerations, and one had a superficial ulcer with large clot. Both patients with lesions were classified as Zargar 2a. In the 3 patients treated with the cooling device, one had no evidence of esophageal mucosal damage, one had esophageal erythema (Zargar 1), and one had a solitary Zargar 2a lesion. At 3-month follow-up, 1 patient in each group had recurrence of atrial fibrillation. Conclusions: The extent of esophageal injury was less severe with a commercially available esophageal cooling device than with reactive instillation of ice-cold water. This pilot study supports further evaluation with a larger clinical trial.
Purpose: We sought to quantify the capabilities of a commercially available cooling device to protect the esophagus from RF injury in an animal model and develop a mathematical model to describe the system and provide a framework from which to advance this technology.Methods: A series of ablations (10 W, duration 30-45 seconds) were performed directly on exposed swine esophagus. Control ablations were performed with static 37°C water, and treatment ablations were performed with water (range 5°C-37°C) circulating within the device. Mucosal lesions were evaluated visually and with target tissue histology. A mathematical model was then developed and compared against the experimental data.Results: All 23 ablations (100%) performed under control conditions produced visible external esophageal lesions; 12 of these (52%) were transmural. Under treatment conditions, only 5 of 23 ablations (22%) produced visible external lesions; none (0%) were transmural. Transmurality of lesions decreased as circulating water temperature decreased, with absolute reduction ranging from 5.1% with the use of 37°C water (p=0.7) to 44.5% with the use of 5°C water (p<0.001). Comparison to the mathematical model showed an R^2 of 0.75, representing good agreement.Conclusions: Under worst-case conditions, with RF energy applied directly to the adventitial side of the esophagus, internal esophageal cooling with an esophageal cooling device provides significant protective effect from thermal injury. A mathematical model of the process provides a means to further investigate this approach to preventing esophageal injury during RF ablation and can serve to guide ongoing clinical investigations currently in progress.
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