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.

Spatial Resolution of Pacemapping and Activation Mapping in Patients with Idiopathic Right Ventricular Outflow Tract Tachycardia

BACKGROUND

The purpose of this study was to compare the spatial resolution of activation mapping and pacemapping in patients undergoing ablation of idiopathic ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT). A direct comparison of the two techniques has not been undertaken.

METHODS AND RESULTS

Electroanatomical activation maps of the RVOT were obtained during VT in 15 patients. Pacemaps were obtained from multiple sites, tagged on the activation map, and scored according the degree of concordance between the paced QRS configuration and that of VT. The site of successful ablation was considered the VT site of origin. Initial endocardial activation away from the site of origin was rapid; the mean area of myocardium activated within the first 10 msec (early activation area, EAA) was 3.0 +/- 1.6 cm(2) (range: 1.3-6.4 cm(2)). Best pacemap scores were always obtained adjacent to the site of origin. Pacemap concordance, and the probability of an exact pacemap match significantly decreased with increasing distance of the pacing site from the site of origin (P < 0.01). All patients had more than one pacing site yielding a best pacemap score. The greatest distance between such sites in an individual patient ranged from 11 to 26 mm (mean: 18 +/- 5 mm), and was strongly correlated with the size of the EAA (r = 0.77, P < 0.001).

CONCLUSIONS

Pacemapping and activation mapping provide similar localizing information. The spatial resolution of each technique is modest, varies between patients, and may be optimized by three-dimensional data display.

Implications and Outcome of Permanent Coronary Sinus Lead Extraction and Reimplantation

OBJECTIVE

We examined the implications and outcome of coronary sinus (CS) lead removal including the feasibility of laser use within the CS.

BACKGROUND

Cardiac anatomy and lead interactions are more complex with the advent of biventricular pacemakers and atrial cardioverters requiring permanent lead/shocking coil placement in the coronary sinus and its branches.

METHODS

Fifty-five permanent cardiac leads were extracted during 2003 in 28 consecutive patients. Our study population included a 10/55 (18%) subset (all males; age 73 +/- 6 years; EF = 0.24 +/- 0.09) that underwent CS (1/10) or vein branch (9/10) lead extraction. Leads were extracted with an excimer laser sheath (n = 4) or by direct traction (n = 6). Median times between implantation and lead removal were 9.5 months (range 5-59) in the laser group and 3 months (range 3-4) in the direct traction group. Indication for extraction was infection (n = 4), dislodgement (n = 3), diaphragm stimulation (n = 2), and elevated threshold (n = 1). The CS was divided into distal, mid, and proximal segments by venogram.

RESULTS

Entry of the laser sheath into the CS was necessary in three of four laser patients. The two distal CS laser cases (left lateral CS coil and anterior-lateral left ventricular (LV) lead) required both 14- and 12-Fr sheaths, separately. The proximal CS laser case (posterior-lateral LV lead) required a 12 Fr sheath. The remaining laser patient required a 12-Fr sheath to pass to the mid SVC. There were no procedural complications as a result of CS lead extraction. Reimplantation of a CS lead was attempted in 7/10 patients at a median of 4 days (range 1-300). CS venograms were available for review in patients before initial implantation (6/10) and after extraction (7/10). The postextraction venograms demonstrated complete occlusion of the vein from which the lead was extracted, and its distal branches, which were unusable in 5/10 (50%). The vein occlusions were present in patients with indwelling leads for greater than 3 months and were independent of extraction method.

CONCLUSIONS

Laser lead extraction in the coronary sinus appears feasible in carefully selected cases with mandatory indications. However, special intraoperative monitoring and echocardiographic imaging with surgical backup ready is strongly recommended. Target vein selection may be limited for the purpose of reimplantation when leads are indwelling for greater than 3 months.

Hypersensitive carotid sinus syndrome due to neurofibromatosis-1 and manifested by repeated episodes of syncope

A 28-year-old patient with neurofibromatosis-1 presented with syncope. The exam demonstrated a mass adjacent and inferior to the right occiput that extended to the posterior lateral right-sided neck. Initial invasive and noninvasive testing was negative. Imaging of her head and neck demonstrated a large neurofibroma enveloping her right carotid sinus without vessel occlusion or evidence of malignancy. An event recorder documented asystole. A pacemaker was implanted to avoid the surgical morbidity of removing the neck mass. The patient has since been free of syncope. We believe neurofibromatosis-1 should be included in the differential of syncope.

Influence of age and gender on the mechanism of supraventricular tachycardia

OBJECTIVES

The objective of this study was to determine the impact of age and gender on the mechanism of paroxysmal supraventricular tachycardia (PSVT).

BACKGROUND

Previous studies have indicated that PSVT mechanism may be influenced by age and gender, but contemporary data are limited.

METHODS

In 1,754 patients undergoing catheter ablation of 1,856 PSVTs between 1991 and 2003, the mechanism was classified as atrioventricular reentrant tachycardia (AVRT), atrioventricular nodal reentrant tachycardia (AVNRT), or atrial tachycardia (AT). Patients with inappropriate sinus tachycardia, atrial flutter, atrial fibrillation, and age <5 years were excluded.

RESULTS

The mean age was 45 +/- 19 years (range 5-96), and the majority were women (62%). Overall, AVNRT was the predominant mechanism (n = 1,042 [56%]), followed by AVRT (n = 500 [27%]) and AT (n = 315 [17%]). There was a strong relationship between age and PSVT mechanism; the proportion of AVRT in both sexes decreased with age, whereas AVNRT and AT increased (PM < .001 by ANOVA). The majority of patients with AVRT were men (273/500 [54.6%]), whereas the majority of patients with AVNRT and AT were women (727/1,042 [70%] and 195/315 [62%], respectively). The distribution of PSVT mechanism was significantly influenced by gender (P < .001). In women, 63% had AVNRT, 20% had AVRT, and 17.0% had AT. In men, 45% had AVNRT, 39% had AVRT, and 17% had AT. AVNRT replaced AVRT as the dominant PSVT mechanism at age 40 in men and at age 10 in women.

CONCLUSIONS

The mechanism of PSVT in patients presenting for ablation is significantly influenced by both age and gender.

Time dependence of mortality risk and defibrillator benefit after myocardial infarction

BACKGROUND

Prophylactic implantable defibrillators (ICDs) improve survival in patients with impaired ventricular function after myocardial infarction (MI), but it is uncertain whether mortality risk and survival benefit depend on the elapsed time from MI.

METHODS AND RESULTS

The Multicenter Automatic Defibrillator Implantation Trial II examined the impact of ICDs on survival in post-MI patients with ejection fractions < or =30%. In 1159 patients, mean time from most recent MI to enrollment was 81+/-78 months. Patients were randomized to an ICD (n=699) or conventional care (n=460) in a 3:2 ratio. Mortality rates (deaths per 100 person-years of follow-up) in both treatment groups were analyzed by time from MI divided into quartiles (<18, 18 to 59, 60 to 119, and > or =120 months). In conventional care patients, these rates increased as time from MI increased (7.8%, 8.4%, 11.6%, 14.0%; P=0.03). Mortality rates in ICD patients were consistently lower in each quartile and showed minimal increase over time (7.2%, 4.9%, 8.2%, 9.0%; P=0.19). Covariate-adjusted hazard ratios for risk of death associated with ICD therapy were 0.97 (95% CI, 0.51 to 1.81; P=0.92) for recent MI (<18 months) and 0.55 (95% CI, 0.39 to 0.78; P=0.001) for remote MI (> or =18 months).

CONCLUSIONS

Mortality risk in patients with ejection fractions < or =30% increases as a function of time from MI. The survival benefit associated with ICDs appears to be greater for remote MI and remains substantial for up to > or =15 years after MI.

Effect of radiofrequency current on previously implanted pacemaker and defibrillator ventricular lead systems

We compared the response of endocardial lead systems to radiofrequency (RF) current delivered during atrio-ventricular junction ablation (AVJA) for atrial fibrillation with uncontrolled ventricular rate in 107 patients. The mean age was 67 +/- 11 years and the mean ejection fraction 42 +/- 15%. Patients were divided into 3 groups based on the type of ventricular lead present at the time of ablation: a previously implanted defibrillator lead (group 3, n = 13), a previously implanted pacemaker lead (group 2, n = 46) or a temporary lead (group 1, n = 48), which was subsequently followed by a permanent lead implantation. During AVJA, a median of 5 RF applications (44 +/- 8 W) were given via 4-5-mm electrodes. All but 1 patient had right-sided lesions, while 6 patients also had left sided lesions. Ventricular pacing thresholds were evaluated immediately pre- and post-ablation at 24 hours and at 1 to 3 months. Increases in ventricular pacing voltage thresholds were noted in all 3 groups over time, with the greatest mean increase in group 3 patients: [table: see text]. A greater than 2-fold increase in pacing thresholds was observed only with previously implanted leads, usually within the first 48 hours. It occurred significantly more often in patients with group 3 (6/13 [46%]) compared to group 2 (6/46 [13%], odds ratio 7.6, P = 0.006). A progressive rise in pacing threshold required lead revision in 2/13 group 3 patients (15%) and 2/46 group 2 patients (4%). While RF current has only minor effects on pacing threshold in most patients with previously implanted ventricular lead systems, clinically important alterations requiring device reprogramming or lead revision may occur. Group 3 are significantly more vulnerable to RF current, though the mechanisms are unclear. Group 1 during AVJA, followed by permanent lead implantation appears advisable. Pts with a previously implanted group 3 who require AVJA should be monitored closely.

A novel sample holder allowing atomic force microscopy on transmission electron microscopy specimen grids: repetitive, direct correlation between AFM and TEM images

A novel sample holder that allows atomic force microscopy (AFM) to be performed on transmission electron microscope (TEM) grids is described. Consequently, AFM and TEM images were repeatedly obtained on exactly the same sample area. For both techniques, a thin carbon film was used as the imaging substrate. Although these techniques have been previously used in conjunction, AFM and TEM images on exactly the same area have not been repeatedly obtained for any system. Correlation of AFM and TEM images is useful for work where the three-dimensional topographical information provided by the AFM could be used to better interpret the two-dimensional images provided by the TEM and vice versa. To demonstrate the applicability of such correlation, new results pertaining to a fibrillar collagen system are summarized.

Arthroscopic suture tying: A comparison of knot types and suture materials

PURPOSE

The purpose of this study was to determine the structural properties of 3 arthroscopically tied knots using 2 different suture materials: the French knot, the Duncan loop knot, and the original Revo knot.

TYPE OF STUDY

Cohort analytic study.

METHODS

The sutures used were No. 1 PDS II, an absorbent monofilament, and No. 1 Ethibond (Ethicon, Somerville, NJ), a braided nonabsorbent material. The resulting 6 suture-knot combinations were individually tested to failure in both open- and closed-loop configurations.

RESULTS

The French knot showed the greatest strength compared with the Duncan loop and the Revo knot with both No. 1 Ethibond and No. 1 PDS II sutures (P <.05). The No. 1 Ethibond exhibited higher initial stiffness than the No. 1 PDS II for all 3 knot types (P <.05). Results were similar for both open and closed-loop configurations. Also, the French knot failed predominantly by suture breakage instead of knot slippage for both suture materials.

CONCLUSIONS

The results of this study suggest that, among the suture and knot combinations investigated in this study, the arthroscopic repair of musculoskeletal injuries should be performed using the French knot and No. 1 Ethibond suture.

Time and cost analysis of repacking medications in unit-of-use containers

OBJECTIVES

To evaluate the effects of repacking drugs in unit-of-use containers in community pharmacies. The purpose of this study was to examine whether unit-of-use repacking reduces routine mechanical "counting and pouring" to allow more time for pharmaceutical care.

DESIGN

Simulation pilot study to evaluate the differences between the existing and proposed systems. Based on the literature, four variables--optimum pack size, time savings, packaging costs, and shelving requirements--were selected for evaluation. Historical prescription data from a chain were used in determining the sample drugs and their optimum pack sizes. Workflow analysis and time study were used to estimate the time savings. Manufacturer bottles, repack bottles, and shelves were measured to determine the impact of using unit-of-use containers on storage requirements.

SETTING

Three community pharmacies in a major drugstore chain in Cincinnati, Ohio.

RESULTS

The 25 fastest-moving solid oral dosage forms, representing 21.6% of all drugs dispensed by the chain, were selected as the sample drugs for the study. The workflow analysis and time study revealed that 0.79 minutes could be saved per prescription if repacked drugs were used. There was an increased cost of approximately $0.05 for every repack bottle used in place of a prescription vial. It was calculated that repacking in unit-of-use containers would increase storage requirements in the pharmacy by 2.5 times if current inventory levels were maintained.

CONCLUSION

Repacking drugs in unit-of-use containers is potentially an inexpensive method to increase usable time in the pharmacy that does not require an increase in personnel or the purchase of additional technology at the store level.

Atypical atrial flutter originating in the right atrial free wall

BACKGROUND

Data from experimental models of atrial flutter indicate that macro-reentrant circuits may be confined by anatomic and functional barriers remote from the tricuspid annulus-eustachian ridge atrial isthmus. Data characterizing the various forms of atypical atrial flutter in humans are limited.

METHODS AND RESULTS

In 6 of 160 consecutive patients referred for ablation of counterclockwise and/or clockwise typical atrial flutter, an additional atypical atrial flutter was mapped to the right atrial free wall. Five patients had no prior cardiac surgery. Incisional atrial tachycardia was excluded in the remaining patient. High-density electroanatomic maps of the reentrant circuit were obtained in 3 patients. Radiofrequency energy application from a discrete midlateral right atrial central line of conduction block to the inferior vena cava terminated and prevented the reinduction of atypical atrial flutter in each patient. Atrial flutter has not recurred in any patient (follow-up, 18+/-17 months; range, 3 to 40 months).

CONCLUSIONS

Atrial flutter can arise in the right atrial free wall. This form of atypical atrial flutter could account for spontaneous or inducible atrial flutter observed in patients referred for ablation and is eliminated with linear ablation directed at the inferolateral right atrium.

Retrograde fast pathway ablation for atrioventricular nodal reentry associated with markedly prolonged PR intervals

Three patients with typical atrioventricular nodal reentrant tachycardia (AVNRT) and markedly prolonged PR intervals (>300 ms) without dual pathway physiology at baseline or during isoproterenol infusion underwent successful fast pathway ablation and remained asymptomatic without recurrent AVNRT, atrioventricular block, or symptomatic bradycardia for a mean of 19 months. In patients with recurrent AVNRT and markedly prolonged PR intervals, selective ablation of the retrograde fast pathway can eliminate AVNRT without further impairment of anterograde atrioventricular nodal function.

Endemic blastomycosis in Mississippi: epidemiological and clinical studies

In order to clarify the epidemiology and clinical spectrum of endemic blastomycosis, we reviewed the charts of 326 culture and/or histologically proven cases of blastomycosis in Mississippi from 1979 to 1988. Cases were dispersed throughout the state, but counties in central and south-central Mississippi reported 63% of all blastomycosis cases. The average annual incidence rate was 1.3 cases per 100,000 population. The majority of cases were in men (male to female ratio 1.7:1), and most patients were aged in their third through seventh decades (82%). Outdoor occupations were noted for only 28.9% of cases. Cases occurred throughout the year with no significant seasonal peak. Although 55% saw a physician within 7 days of onset of illness, 29% presented after 1 month. Despite early presentation, diagnosis was often delayed for more than 1 month (43.3%). Single organs were involved in 82.8% of cases. For all cases, organ systems involved included lungs (91.4%), skin (18.1%), bone (4.3%), genitourinary system (1.8%), and central nervous system (1.2%). The presence of skin or bone disease was associated with multiorgan involvement. Thirty-three patients died (11.5%), 6 of whom received no therapy. Patients who died were significantly older than those who survived. A successful outcome without relapse was noted in 86.5% of amphotericin B-treated patients and in 81.7% of ketoconazole-treated patients. The relapse rate for ketoconazole-treated patients was higher than for amphotericin B-treated patients (14% and 3.9% respectively).

Re-engineering a pharmacy work system and layout to facilitate patient counseling

The development and evaluation of a new work system and facility design for a chain of community pharmacies are described. A new work system was developed to optimize utilization of pharmacist and technician time and allow the pharmacy to increase patient counseling without adding personnel. In the new system, pharmacists would review prescriptions, check technicians' work, and dispense prescriptions, counseling patients as needed; technicians would enter prescriptions into the pharmacy computer and fill them. The existing work system and design were evaluated in June and July of 1992 by observing, classifying, and recording activities of pharmacy personnel three days per week at six pharmacies in the chain. Pharmacy designs that would work with the new work system were created by a university design class after consultation with representatives of the pharmacy chain and the university's college of pharmacy. The pharmacy chain selected one design, and a detailed floor plan and specifications were created. To test how the new design and system would work at each of the six test pharmacies, a computer simulation program was developed and verified by using the data collected on the existing pharmacy operations. Computer simulation showed that, with the new design and system, increasing patient counseling would increase patient waiting time slightly but would not require additional personnel. The layout and work system in a chain of community pharmacies were redesigned to facilitate patient counseling and make the best use of employee time.

A modified free gracilis flap in the rat

We present in this paper the use of a combined neurovascularized flap of gracilis muscle and inguinal skin in the rat with the femoral vessels and obturator nerve serving as the pedicles. The epigastric, saphenous, and muscular branch vessels arising from the femoral vessels were preserved, and a portion of adductor magnus muscle was included in the flap to protect the delicate muscle vessels at their origins. The inguinal skin and muscle flap both had independent blood supplies, thus separate assessment of muscle and skin rejection was possible in the single transplanted "packet." The muscle flap with the reconnected motor nerve regained contractile ability upon nerve stimulation within 30 days after the iso-transplantation. The results suggest that the modified gracilis myocutaneous flap provides an ideal model for transplantation research.

Listerial infections in patients with systemic lupus erythematosus

Infection with Listeria monocytogenes is known to occur more frequently in immunosuppressed patients, including those receiving high-dose prednisone or cytotoxic therapy for collagen vascular disease. We reviewed three cases of listeriosis and systemic lupus erythematosus (SLE) seen at our institution, in addition to five cases reported in the English literature. Seven of the eight patients had non-CNS listerial infections. All patients but one had associated risk factors of either renal failure or pregnancy. From our review, we found that listeriosis is uncommon in SLE, and patients without renal failure or pregnancy do not seem to be at increased risk for listeriosis. Although most patients were treated with high-dose prednisone, with or without cytotoxic drugs, the role of immunosuppression by these drugs as a risk factor for listeriosis remained unclear.

[Preliminary study of cartilage repair with autologous periosteum and fibrin adhesive system]

The potential surgical transplantation with autogenous periosteal grafts and Fibrin Adhesive System (FAS) was attempted in a rabbit model. The grafts were taken from the tibia, transplanted and fixed with FAS to artificial full-thickness (0.4 x 0.3 cm) defect on the femoral condyle. Histologic and ultrastructural findings revealed chondrocyte regeneration in the control, grafted, and graft/FAS treated group at week 6; however, chondrogenesis of the reparative tissue was best demonstrated in the graft/FAS group. At week 12, the interface between the reparative tissue and the surrounding tissue was invisible in the FAS/graft group, as compared with the well-defined interface in the grafted group and the control. The results strongly suggest that FAS-treated periosteal transplant is a potential model for the repair of articular cartilage defects. Although the results are preliminary, all seem promising in the clinical aspects.

Development of self-recognition in chimpanzees (Pan troglodytes)

Chimpanzees (Pan troglodytes) demonstrate the ability to recognize themselves in mirrors, yet investigations of the development of self-recognition in chimpanzees are sparse. Twelve young chimpanzees, grouped by age, were given mirror exposure and tested for self-recognition and contingent movement. All 6 juveniles, 4 and 5 years old, exhibited mirror-guided, mark-directed behavior and clear evidence of self-recognition. In contrast, among the infants, only the oldest group of 2 1/2-year-olds exhibited clear evidence of self-recognition. All chimpanzees exhibited both self-directed behaviors and contingent movements. These results suggest that self-recognition occurs at a slightly older age in chimpanzees than in human infants. In humans, self-recognition is linked with other cognitive abilities. The results conform to the general pattern that great apes exhibit many cognitive skills comparable to those of 2-year-old humans.

Initiation of transcription by T7 RNA polymerase as its natural promoters

A kinetic assay has been developed to measure the strength of natural T7 promoters. By determining the rate of appearance of initiation products in the presence of constant concentrations of T7 RNA polymerase, an incomplete mixture of ribonucleoside triphosphates, and increasing promoter concentrations, a maximum rate of product formation (Vmax) and a promoter concentration giving half of the maximal activity ([P]Vmax/2) can be determined for any cloned T7 promoter. On supercoiled plasmids, it was found that the [P]Vmax/2 measured for the six promoters phi 1.1B, phi 1.3, phi 3.8, phi 6.5, phi 10, and phi 13 ranged from 3.4 +/- 1.1 to 12.0 +/- 2.4 nM while the Vmax values showed no significant trends. On plasmids that had been linearized by cleavage at a single site with a restriction endonuclease, the cloned T7 promoters assayed fell into two broad classes that appear to be characterized by the T7 class II and III promoters. Generally, the class II promoters required higher promoter concentrations to produce half of the maximum rates of initiation ([P]Vmax/2 values) than the class III promoters. The [P]Vmax/2 values for the class II promoters ranged from 20 +/- 2.7 to 23 +/- 3.6 nM, while the [P]Vmax/2 values for the class III promoters phi 10 and phi 13 were 13 +/- 1.6 nM and 7.8 +/- 1.4 nM. The one exception is the class III promoter phi 6.5 whose [P] Vmax/2 (17 +/- 5 nM) falls between the [P]Vmax/2 values of the class II promoters and the strong class III promoters. The Vmax values measured on linear templates are variable, but it appears that phi 10 is more active than the other five promoters.

Vascularized autogenous canine coccygeal bone transfer

Based on cadaver studies in dogs, the 8th, 9th, or 10th canine coccygeal vertebra with overlying skin was designed for free vascularized bone transfer. In six dogs the coccygeal osteocutaneous flap was transferred to fill a defect of the tibia, anastomosing the median caudal artery and one of the two caudal veins to the tibial vessels. The overlying skin provided a reliable monitoring system for the transferred tissue. The behavior of the vascularized coccygeal vertebrae was then evaluated with radiographic and histologic examination and compared with control vertebrae transferred without reconnection of the blood vessels. The results revealed that the canine coccygeal bone graft is a reliable vascularized osteocutaneous flap, which can be applied either in clinical veterinary surgery or in orthopedic microsurgical research.