Implementation of an intravenous sotalol initiation protocol: Implications for feasibility, safety, and length of stay

INTRODUCTION

Oral sotalol initiation requires a multiple-day, inpatient admission to monitor for QT prolongation during loading. A 1-day intravenous (IV) sotalol loading protocol was approved by the United States Food and Drug Administration in March 2020, but limited data on clinical use and administration currently exists. This study describes implementation of an IV sotalol protocol within an integrated health system, provides initial efficacy and safety outcomes, and examines length of stay (LOS) compared with oral sotalol initiation.

METHODS

IV sotalol was administered according to a prespecified initiation protocol to adult patients with refractory atrial or ventricular arrhythmias. Baseline characteristics, safety and feasibility outcomes, and LOS were compared with patients receiving oral sotalol over a similar time period.

RESULTS

From January 2021 to June 2022, a total of 29 patients (average age 66.0 ± 8.6 years, 27.6% women) underwent IV sotalol load and 20 patients (average age 60.4 ± 13.9 years, 65.0% women) underwent oral sotalol load. The load was successfully completed in 22/29 (75.9%) patients receiving IV sotalol and 20/20 (100%) of patients receiving oral sotalol, although 7/20 of the oral sotalol patients (35.0%) required dose reduction. Adverse events interrupting IV sotalol infusion included bradycardia (seven patients, 24.1%) and QT prolongation (three patients, 10.3%). No patients receiving IV or oral sotalol developed sustained ventricular arrhythmias before discharge. LOS for patients completing IV load was 2.6 days shorter (mean 1.0 vs. 3.6, p < .001) compared with LOS with oral load.

CONCLUSION

IV sotalol loading has a safety profile that is similar to oral sotalol. It significantly shortens hospital LOS, potentially leading to large cost savings.

Esophageal temperature management during cryoballoon ablation for atrial fibrillation

INTRODUCTION

Esophageal thermal injury (ETI) is a well-recognized complication of atrial fibrillation (AF) ablation. Previous studies have demonstrated that direct esophageal cooling reduces ETI during radiofrequency AF ablation. The purpose of this study was to evaluate the use of an esophageal warming device to prevent ETI during cryoballoon ablation (CBA) for AF.

METHODS

This prospective, double-blinded study enrolled 42 patients with symptomatic AF undergoing CBA. Patients were randomized to the treatment group with esophageal warming (42°C) using recirculated water through a multilumen, silicone tube inserted into the esophagus (EnsoETM®; Attune Medical) (WRM) or the control group with a luminal single-electrode esophageal temperature monitoring probe (LET). Patients underwent upper endoscopy esophagogastroduodenoscopy (EGD) the following day. ETI was classified into four grades.

RESULTS

Baseline patient characteristics were similar between groups. Procedural characteristics including number of freezes, total freeze time, early freeze terminations, coldest balloon temperature, procedure duration, posterior wall ablation, and proton pump inhibitor and transesophageal echocardiogram use before procedure were not different between groups. The EGD was completed in 40/42 patients. There was significantly more ETI in the WRM group compared to the LET group (n = 8 [38%] vs. n = 1 [5%], p = 0.02). All ETI lesions were grade 1 (erythema) or 2 (superficial ulceration). Total freeze time in the left inferior pulmonary vein was predictive of ETI (360 vs. 300 s, p = 0.03).

CONCLUSION

Use of a luminal heat exchange tube for esophageal warming during CBA for AF was paradoxically associated with a higher risk of ETI.

Long-term electrical performance of Attain Performa quadripolar left ventricular leads with all steroid-eluting electrodes: Results from a large worldwide clinical trial

BACKGROUND

Steroid-eluting (SE) electrodes suppress local inflammation and lower pacing capture thresholds (PCT); however, their effectiveness on quadripolar left ventricular (LV) leads in the cardiac vein is not fully studied. We evaluated the effectiveness of SE on all four LV pacing electrodes in human subjects enrolled in the Medtronic Attain® Performa™ quadripolar LV lead study.

METHODS

A total of 1,097 subjects were included in this evaluation. At each follow-up visit (1, 3, 6, and 12 months), LV PCT and pacing impedance were measured using either manual or automated testing methods. Summary statistics for PCT and impedance values were obtained for implant and each scheduled follow-up visit for all lead models.

RESULTS

Average extended bipolar (LV electrode to right ventricular Coil) PCTs for the four LV SE pacing electrodes (LV1, LV2, LV3, and LV4) on the three shapes of the quadripolar LV leads were 1.06 ± 0.97 V, 1.38 ± 1.26 V, 1.51 ± 1.33 V, and 2.25 ± 1.63 V, respectively, at 0.5-ms pulse width. PCTs remained low and stable throughout the 12-month follow-up period.

CONCLUSION

This clinical trial demonstrated that SE on all LV pacing electrodes is associated with low and stable PCTs for all quadripolar LV lead electrodes, resulting in multiple viable vectors for LV pacing. The large number of available vectors facilitates basal pacing, avoidance of PNS, and potentially prolongs generator longevity due to lower PCTs.

Bronchial effects of cryoballoon ablation for atrial fibrillation

BACKGROUND

Damage to extracardiac structures, including the esophagus and phrenic nerve, is a known complication of cryoballoon ablation (CBA) during pulmonary vein (PV) isolation for atrial fibrillation (AF). Other adjacent structures, including the pulmonary bronchi and lung parenchyma, may be affected during CBA at the PV ostia.

OBJECTIVE

The purpose of this study was to prospectively study the bronchial effects of CBA in humans undergoing CBA for PV isolation.

METHODS

Ten patients undergoing CBA for AF under general anesthesia were enrolled in an institutional review board-approved prospective observational study. Real-time bronchoscopy was performed during cryoablation of PVs adjacent to pulmonary bronchi to monitor for thermal injury. Patients were followed for the development of respiratory complaints postprocedure.

RESULTS

In 7 of 10 patients (70%) and in 13 of 22 freezes (59%), ice formation was visualized in the left mainstem bronchus during CBA in the left upper PV. Ice formation was not seen in the right mainstem bronchus during right upper PV CBA. The average time to ice formation was 89 seconds. There was no significant difference (P = -.45) in average minimum balloon temperature during freezes with ice formation (-48.5°C) and freezes without ice formation (-46.3°C). No patients went on to develop respiratory complications.

CONCLUSION

Unrecognized ice formation occurs frequently in the left mainstem bronchus during CBA for AF. This information helps explain the source of cough and hemoptysis in some patients who undergo CBA. The long-term consequences of this novel finding and the implications for procedural safety are unknown.

Reconnection Rate and Long-Term Outcome with Adenosine Provocation During Cryoballoon Ablation for Pulmonary Vein Isolation

Background

Adenosine can unmask dormant conduction during pulmonary vein isolation (PVI) for atrial fibrillation (AF). Studies of adenosine use in radiofrequency PVI show high reconnection rates and conflicting results for long-term success, however there is limited data with cryoballoon ablation (CBA).

Methods

A prospectively maintained database of patients undergoing first CBA at a single institution was analyzed. Adenosine use was at the discretion of the primary operator. Additional freezes were delivered for reconnected veins until dormant conduction was eliminated. The primary endpoint, time to AF recurrence defined as any episode < 30 seconds after a 3-month blanking period, was assessed by Kaplan-Meier analysis.

Results

From 2011 to 2015, 406 patients underwent CBA, 361 of whom had > 3 months follow-up. The mean age was 61.7 years, 69% were male, and the prevalence of paroxysmal AF was 79% with no significant difference between those that did and did not receive adenosine (77% vs 86%, respectively, p = 0.23). Adenosine testing was performed in 78 patients (21.6%) with a mean dose of 10.6 mg/vein. Of the 306 veins evaluated, 17 (6%) demonstrated dormant conduction. Over a median 14.4 months follow-up, there was no significant difference in freedom from AF with adenosine use (p= 0.86).

Conclusions

Dormant conduction with adenosine is uncommon following CBA and its use does not improve long-term success rates.

The Safety of Cardiac and Thoracic Magnetic Resonance Imaging in Patients with Cardiac Implantable Electronic Devices

RATIONALE AND OBJECTIVES

Studies reporting the safety of magnetic resonance imaging (MRI) in patients with a cardiac implantable electronic device (CIED) have mostly excluded examinations with the device in the magnet isocenter. The purpose of this study was to describe the safety of cardiac and thoracic spine MRI in patients with a CIED.

MATERIALS AND METHODS

The medical records of patients with a CIED who underwent a cardiac or thoracic spine MRI between January 2011 and December 2014 were reviewed. Devices were interrogated before and after imaging with reprogramming to asynchronous pacing in pacemaker-dependent patients. The clinical interpretability of the MRI and peak and average specific absorption rates (SARs, W/kg) achieved were determined.

RESULTS

Fifty-eight patients underwent 51 cardiac and 11 thoracic spine MRI exams. Twenty-nine patients had a pacemaker and 29 had an implantable cardioverter defibrillator. Seventeen percent (n = 10) were pacemaker dependent. Fifty-one patients (89%) had non-MRI-conditional devices. There were no clinically significant changes in atrial and ventricular sensing, impedance, and threshold measurements. There were no episodes of device mode changes, arrhythmias, therapies delivered, electrical reset, or battery depletion. One study was prematurely discontinued due to a patient complaint of chest pain of which the etiology was not determined. Across all examinations, the average peak SAR was 2.0 ± 0.85 W/kg with an average SAR of 0.35 ± 0.37 W/kg. Artifact significantly limiting the clinical interpretation of the study was present in 33% of cardiac MRI studies.

CONCLUSIONS

When a comprehensive CIED magnetic resonance safety protocol is followed, the risk of performing 1.5-T magnetic resonance studies with the device in the magnet isocenter, including in patients who are pacemaker dependent, is low.

Improved upper limits on the stochastic gravitational-wave background from 2009-2010 LIGO and Virgo data

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors. Consistent with predictions from most stochastic gravitational-wave background models, the data display no evidence of a stochastic gravitational-wave signal. Assuming a gravitational-wave spectrum of Ω_{GW}(f)=Ω_{α}(f/f_{ref})^{α}, we place 95% confidence level upper limits on the energy density of the background in each of four frequency bands spanning 41.5-1726 Hz. In the frequency band of 41.5-169.25 Hz for a spectral index of α=0, we constrain the energy density of the stochastic background to be Ω_{GW}(f)<5.6×10^{-6}. For the 600-1000 Hz band, Ω_{GW}(f)<0.14(f/900  Hz)^{3}, a factor of 2.5 lower than the best previously reported upper limits. We find Ω_{GW}(f)<1.8×10^{-4} using a spectral index of zero for 170-600 Hz and Ω_{GW}(f)<1.0(f/1300  Hz)^{3} for 1000-1726 Hz, bands in which no previous direct limits have been placed. The limits in these four bands are the lowest direct measurements to date on the stochastic background. We discuss the implications of these results in light of the recent claim by the BICEP2 experiment of the possible evidence for inflationary gravitational waves.

Early safety and efficacy of percutaneous left atrial appendage suture ligation: results from the U.S. transcatheter LAA ligation consortium

BACKGROUND

Transcatheter left atrial appendage (LAA) ligation may represent an alternative to oral anticoagulation for stroke prevention in atrial fibrillation.

OBJECTIVES

This study sought to assess the early safety and efficacy of transcatheter ligation of the LAA for stroke prevention in atrial fibrillation.

METHODS

This was a retrospective, multicenter study of consecutive patients undergoing LAA ligation with the Lariat device at 8 U.S. sites. The primary endpoint was procedural success, defined as device success (suture deployment and <5 mm leak by post-procedure transesophageal echocardiography), and no major complication at discharge (death, myocardial infarction, stroke, Bleeding Academic Research Consortium bleeding type 3 or greater, or cardiac surgery). Post-discharge management was per operator discretion.

RESULTS

A total of 154 patients were enrolled. Median CHADS2 score (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, prior stroke, transient ischemic attack, or thromboembolism [doubled]) was 3 (interquartile range: 2 to 4). Device success was 94%, and procedural success was 86%. A major complication occurred in 15 patients (9.7%). There were 14 major bleeds (9.1%), driven by the need for transfusion (4.5%). Significant pericardial effusion occurred in 16 patients (10.4%). Follow-up was available in 134 patients at a median of 112 days (interquartile range: 50 to 270 days): Death, myocardial infarction, or stroke occurred in 4 patients (2.9%). Among 63 patients with acute closure and transesophageal echocardiography follow-up, there were 3 thrombi (4.8%) and 13 (20%) with residual leak.

CONCLUSIONS

In this initial multicenter experience of LAA ligation with the Lariat device, the rate of acute closure was high, but procedural success was limited by bleeding. A prospective randomized trial is required to adequately define clinical efficacy, optimal post-procedure medical therapy, and the effect of operator experience on procedural safety.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts. Both searches use the event time and sky localization to improve the gravitational wave search sensitivity as compared to corresponding all-time, all-sky searches. We find no evidence of a gravitational wave signal associated with any of the IPN GRBs in the sample, nor do we find evidence for a population of weak gravitational wave signals associated with the GRBs. For all IPN-detected GRBs, for which a sufficient duration of quality gravitational wave data are available, we place lower bounds on the distance to the source in accordance with an optimistic assumption of gravitational wave emission energy of 10(-2)M⊙c(2) at 150 Hz, and find a median of 13 Mpc. For the 27 short-hard GRBs we place 90% confidence exclusion distances to two source models: a binary neutron star coalescence, with a median distance of 12 Mpc, or the coalescence of a neutron star and black hole, with a median distance of 22 Mpc. Finally, we combine this search with previously published results to provide a population statement for GRB searches in first-generation LIGO and Virgo gravitational wave detectors and a resulting examination of prospects for the advanced gravitational wave detectors.

Use of an electrocardiographic screening tool to determine candidacy for a subcutaneous implantable cardioverter-defibrillator

BACKGROUND

An electrocardiographic (ECG) screening test has been developed to identify patients being considered for a totally subcutaneous implantable cardioverter-defibrillator (S-ICD) at risk for T-wave oversensing.

OBJECTIVE

The purpose of this study was to determine the proportion of potential S-ICD recipients who fail the ECG screening test and to identify predictors of failure.

METHODS

Patients who already have an ICD but are not receiving antibradycardia pacing are representative of patients who might be considered for an S-ICD. One hundred such outpatients were enrolled in the study. Surface rhythm strips were recorded along the sensing vectors of the S-ICD system and the screening template applied. Clinical and standard ECG characteristics of patients who failed the test were compared to those who passed.

RESULTS

Patients had the following characteristics: 72% male, age 57 ± 16 years, body mass index 29 ± 6 kg/m(2), left ventricular ejection fraction 43% ± 17%, QRS duration 109 ± 23 ms, QTc interval 447 ± 39 ms, 44% had coronary disease, and 55% had heart failure. Among the 100 patients, 8% failed the screening test. There were no differences in patient clinical characteristics and most standard ECG measurements. However, patients with T-wave inversions in standard ECG leads I, II, and aVF had a 45% chance of failing.

CONCLUSION

Eight percent of potential S-ICD patients were not eligible for the S-ICD after failing the screening test designed to identify patients susceptible to T-wave oversensing. Patients with T-wave inversions in leads I, II, and aVF on a standard ECG were 23 times more likely to fail. More work is needed in S-ICD sensing algorithms to increase patient eligibility for the S-ICD.

Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time. We find no evidence of GW signals from cosmic strings. From this result, we derive new constraints on cosmic string parameters, which complement and improve existing limits from previous searches for a stochastic background of GWs from cosmic microwave background measurements and pulsar timing data. In particular, if the size of loops is given by the gravitational backreaction scale, we place upper limits on the string tension Gμ below 10(-8) in some regions of the cosmic string parameter space.

Widely tunable midinfrared difference frequency generation in orientation-patterned GaAs pumped with a femtosecond Tm-fiber system

We demonstrate a midinfrared source tunable from 6.7 to 12.7 μm via difference frequency generation (DFG) in orientation-patterned GaAs, with 1.3 mW average output power. The input pulses are generated via Raman self-frequency shift of a femtosecond Tm-doped-fiber laser system in a fluoride fiber. We numerically model the DFG process and show good agreement between simulations and experiments. We use this numerical model to show an improved design using longer pump pulses.

Prevalence and predictors of cable extrusion and loss of electrical integrity with the Riata defibrillator lead

INTRODUCTION

Recently, a medical advisory was issued regarding the Riata and Riata ST silicone endocardial defibrillator leads (St. Jude Medical, Sylmar, CA, USA) addressing the issue of conductor cables extruding in an "inside-out" fashion from the main body of the lead. However, little data exist to guide our management of patients with these leads.

METHODS AND RESULTS

A retrospective analysis was performed of 84 patients with a Riata lead who underwent cine-fluoroscopy and electrical evaluation as part of a screening program to assess for cable extrusion. All leads screened were dual-coil except for one single-coil lead. Of 84 patients, 23 patients (27.4%) had fluoroscopic evidence of cable extrusion. Multivariate analysis showed that the duration of time since lead implant and the presence of multiple right ventricular leads were significantly associated with cable extrusion. All 23 patients had normal electrical parameters on routine device interrogation. Fifteen of these 23 patients (65%) with extruded cables had high-voltage shocks within 12 months of lead screening; only one patient demonstrated postshock electrical abnormalities.

CONCLUSIONS

The prevalence of cable extrusion in dual-coil Riata leads is significantly higher at 27.4% than previously reported. The duration of time since implantation and the presence of multiple right ventricular leads are associated with cable extrusion. High-energy shocks did not reveal electrical abnormalities in most patients with cable extrusion.

Incidence of tissue coring during transseptal catheterization when using electrocautery and a standard transseptal needle

BACKGROUND

The application of radiofrequency electrocautery to a standard, open-ended transseptal needle has been used to facilitate transseptal puncture (TSP). The purpose of this study was to determine the incidence of cardiac tissue coring when this technique is used.

METHODS AND RESULTS

A model using excised swine hearts submerged in a saline-filled basin was developed to simulate TSP with electrocautery and a standard transseptal needle. Punctures were performed without the use of electrocautery and by delivering radiofrequency energy to the transseptal needle using a standard electrocautery pen at 3 target sites (fossa ovalis, non-fossa ovalis septum, and aorta). The tissue of the submerged heart was gently tented, and the needle was advanced on delivery of radiofrequency. The devices were retracted, and the needle was flushed in a collection basin. None of the TSPs without cautery caused tissue coring. For TSPs using electrocautery, the frequency of coring was at least 21% for any puncture permutation used in the study and averaged 37% at septal sites (P<0.001 compared with punctures without cautery). Tissue coring occurred in 33 of 96 (35%) punctures through the fossa ovalis and in 38 of 96 (40%) punctures through non-fossa ovalis septum. The frequency of tissue coring at aortic sites was 62 of 96 (65%), which was significantly higher than at the septal sites (P<0.001).

CONCLUSIONS

In an animal preparation, TSP at the level of the fossa ovalis using electrocautery and a standard open-ended Brockenbrough needle resulted in coring of the septal tissue in 35% of cases (33 of 96 punctures).

Salivary gland anlage tumor in a neonate presenting with respiratory distress: radiographic and pathologic correlation

We present a case of congenital salivary gland anlage tumor (SGAT) of the nasal septum in a 2-week-old infant who had difficulty breathing through her nose since birth. CT and MR imaging demonstrated a circumscribed mass within the nasal cavity that did not communicate with the intracranial compartment. Differential diagnosis and clinical significance of recognizing this rare lesion are reviewed.

Successful external cardioversion of atrial fibrillation in patients referred to an electrophysiologist for internal cardioversion

BACKGROUND

Internal cardioversion of atrial fibrillation with direct current energy has become an increasingly employed technique for patients who fail external cardioversion.

HYPOTHESIS

The purpose of this study was to determine whether internal cardioversion could be avoided by careful attention to cardioversion technique in a group of patients referred specifically for internal cardioversion after failed external cardioversion by community cardiologists.

METHODS

We performed external cardioversion utilizing two operators applying significant pressure to the thorax with up to 360 J prior to the planned internal cardioversion in 20 patients referred for internal cardioversion after failed attempts at external cardioversion.

RESULTS

Sixteen patients (80%) were successfully cardioverted and avoided the risk, inconvenience, and cost of internal cardioversion.

CONCLUSION

External cardioversion with significant anterior paddle pressure by two operators can decrease the need for internal cardioversion in a significant portion of patients referred to electrophysiologists for internal cardioversion and should be considered prior to an invasive procedure.