Abstract
Background
Device impedance for subcutaneous ICDs (S-ICDs) may rise over time reflecting changes in tissue electrical conduction due to fibrosis from the natural foreign body response, ...increasing the risk of defibrillation failure. A biologic envelope optimized for S-ICDs may mitigate fibrosis and encourages angiogenesis around the device possibly decreasing impedance rise over time. The S-ICD system performs routine low-voltage Z-lead (LVZ) impedance testing (impedance between shocking coil and can) that may provide insight into the impedance changes on device functionality and efficacy over time.
Purpose
Explore early and late impedance changes over time in S-ICDs implanted with and without envelopes using periodic LVZ measurements.
Methods
30 patients received S-ICDs (15 with envelope) between 1/2017 and 3/2021, after excluding those with device complications, uncontrolled comorbidities, or recent cardiac surgery. Impedance data was recorded at initial implantation. LVZ impedance data was extracted from the wireless remote monitoring system, trended over 0–4 years post implant, and analyzed blinded to patient information.
Results
24 patients (12 envelope) had evaluable implant and chronic data sets. Baseline clinical characteristics were similar between groups. Impedance in general was higher in the envelope group at initial implantation (LVZ mean 89 Ω vs 74 Ω) and throughout the first year. Comparing envelope to no envelope, the initial average shock impedance was 87.3±30.50 vs 66.7±10.40, followed by an average low-V impedance drop of 29 Ω vs 17 Ω during the first month, with a recovery to 109 Ω vs 91 Ω at 30 months post implant. After 30 months, impedance trends demonstrated a modest linear increase up to 48 months in the no envelope group in comparison with a modest decrease in the envelope group (sample sizes too small to determine significance) (Figure 1).
Conclusion
The results demonstrate periodic LVZ testing in the S-ICD monitoring system can reliably trend changes in system impedance over time. Impedance measurements within the first 6–7 months (and most markedly within the first 3 months) appear to be transiently lower than the values seen after this timepoint suggesting that early impedance measurements may not predict steady-state impedance. Further studies are needed to explore the impact of envelope use and the S-ICD impedance changes beyond 30 months.
Funding Acknowledgement
Type of funding sources: None.
P. G. Hartley, J. R. Galvin, G. W. Hunninghake, J. A. Merchant, S. J. Yagla, S. B. Speakman and D. A. Schwartz
Department of Internal Medicine, University of Iowa, Iowa City 52242.
To assess the ...validity of computer-assisted methods in analyzing the lung
parenchyma imaged with high-resolution computed tomography (HRCT), we
compared computer-derived estimates of lung density to other, more
traditional, measures of parenchymal injury in 24 subjects with idiopathic
pulmonary fibrosis (IPF) and 60 subjects with extensive occupational
exposure to asbestos. Gray scale density histograms were constructed from
the HRCT images. The gray scale histogram of both study groups was of a
skewed unimodal distribution. However, compared with the asbestos-exposed
subjects, the patients with IPF had a gray scale distribution that was
significantly shifted to the right (greater density) and flatter. In a
multivariate analysis, after controlling for age and cigarette smoking, we
found that the mean and median gray scale densities were independently
associated with the presence of moderate-to-severe dyspnea, a higher
International Labour Office chest X-ray category, a lower forced vital
capacity, and a higher concentration of macrophages and eosinophils in the
bronchoalveolar lavage fluid. These factors accounted for > 70% of the
variance of the mean and median gray scale densities. Interestingly, no
differences in gray scale density measures were noted between patients with
IPF and patients with asbestosis when these other factors were taken into
account. Our results suggest that computer-derived density analysis of the
lung parenchyma on the HRCT scan is a valid, clinically meaningful, and
objective measure of interstitial lung disease.
To assess further the clinical significance of asbestos-induced pleural fibrosis, we used a computer algorithm to reconstruct images three dimensionally from the high-resolution computerized ...tomography (HRCT) scan of the chest in 60 asbestos-exposed subjects. Pulmonary function tests, chest radiographs, and HRCT scans were performed on all study subjects. The volume of asbestos-induced pleural fibrosis was computed from the three-dimensional reconstruction of the HRCT scan. Among those with pleural fibrosis identified on the HRCT scan (n = 29), the volume of the pleural lesion varied from 0.01% (0.5 ml) and 7.11% (260.4 ml) of the total chest cavity. To investigate the relationship between asbestos-induced pleural fibrosis and restrictive lung function, we compared the computer-derived estimate of pleural fibrosis to the total lung capacity and found that these measures were inversely related (r = -0.40; P = 0.002). After controlling for age, height, pack-years of cigarette smoking, and the presence of interstitial fibrosis on the chest radiograph, the volume of pleural fibrosis identified on the three-dimensional reconstructed image from the HRCT scan was inversely associated with the total lung capacity (P = 0.03) and independently accounted for 9.5% of the variance of this measure of lung volume. These findings further extend the scientific data supporting an independent association between pleural fibrosis and restrictive lung function.
This Letter reports on a search for nu(mu) --> nu(e) transitions by the MINOS experiment based on a 3.14x10(20) protons-on-target exposure in the Fermilab NuMI beam. We observe 35 events in the Far ...Detector with a background of 27+/-5(stat)+/-2(syst) events predicted by the measurements in the Near Detector. If interpreted in terms of nu(mu) --> nu(e) oscillations, this 1.5sigma excess of events is consistent with sin2(2theta(13)) comparable to the CHOOZ limit when |Delta m2|=2.43x10(-3) eV2 and sin2(2theta(23))=1.0 are assumed.
We report the first detailed comparisons of the rates and spectra of neutral-current neutrino interactions at two widely separated locations. A depletion in the rate at the far site would indicate ...mixing between nu(mu) and a sterile particle. No anomalous depletion in the reconstructed energy spectrum is observed. Assuming oscillations occur at a single mass-squared splitting, a fit to the neutral- and charged-current energy spectra limits the fraction of nu(mu) oscillating to a sterile neutrino to be below 0.68 at 90% confidence level. A less stringent limit due to a possible contribution to the measured neutral-current event rate at the far site from nu(e) appearance at the current experimental limit is also presented.
We measure the horizontal (|cos(
θ
z
)|<0.14 corresponding to a slant depth cut 14 kmwe) neutrino-induced muon flux (
E
μ>1.8 GeV) in Soudan 2 to be 4.01
±
0.50
±
0.30
×
10
−13 cm
−2
sr
−1
s
−1. From ...the absence of horizontal muons with large energy loss, we set a limit on the flux of muon neutrinos from active galactic nuclei.
The rate of high energy cosmic ray muons as measured underground is shown to be strongly correlated with upper‐air temperatures during short‐term atmospheric (10‐day) events. The effects are seen by ...correlating data from the MINOS underground detector and temperatures from the European Centre for Medium Range Weather Forecasts during the winter periods from 2003–2007. This effect provides an independent technique for the measurement of meteorological conditions and presents a unique opportunity to measure both short and long‐term changes in this important part of the atmosphere.
Bioautography on thin-layer chromatograms was used to isolate six antifungal sesquiterpenes and three bisbibenzyls from
Bazzania trilobata. Their antifungal activities were compared by microtiter ...plate tests. Furthermore gymnomitr-8(12)-en-4-one and the new coumarin 7,8-dihydroxy-coumarin-7-
O-β-
d-glucuronide were isolated.
A dichloromethane and a methanol extract of the liverwort
Bazzania trilobata showed antifungal activity against the phytopathogenic fungi
Botrytis cinerea,
Cladosporium cucumerinum,
Phythophthora infestans,
Pyricularia oryzae and
Septoria tritici. Bioautography on thin-layer chromatograms was used to isolate six antifungal sesquiterpenes: 5- and 7-hydroxycalamenene, drimenol, drimenal, viridiflorol, gymnomitrol and three bisbibenzyls: 6
′,8
′-dichloroisoplagiochin C, isoplagiochin D and 6
′-chloroisoplagiochin D. Furthermore we report the isolation of gymnomitr-8(12)-en-4-one and the new coumarin 7,8-dihydroxycoumarin-7-
O-β-
d-glucuronide. Their structures have been elucidated based on extensive NMR spectral evidence.
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