Pre-procedural pacing bias among transcatheter aortic valves with higher post-procedure pacing rates: evidence from the UK TAVI Registry.

Rates of permanent pacemaker (PPM) implantation following transcatheter aortic valve implantation (TAVI) are higher than following surgery and are dependent on patient factors and valve type. There is an increasing trend towards pre-emptive PPM insertion in patients with significant conduction disease prior to TAVI. We report results from the British Cardiovascular Intervention Society (BCIS) on pre- and post-procedural PPM implantation in the TAVI population. All centres in the United Kingdom performing TAVI are required to submit data on all TAVI procedures to the National database which are then reported annually. During 2015, there were 2373 TAVI procedures in the UK. 22.4% of TAVI patients had a PPM implanted either pre-procedure (including the distant past), or during the in-hospital procedural episode. Of these, 7.9% were pre-procedure and 14.5% post-procedure. Overall PPM rates were Edwards Sapien (13.5%), Medtronic CoreValve (28.2%) and Boston Lotus (42.1%; p < 0.01). Pre-procedure pacing rates were Edwards Sapien (6.0%), Medtronic CoreValve (9.1%) and Boston Lotus (12.3%; p < 0.01). Pre-procedural pacing rates for the Boston Lotus valve have risen year-on-year from 5.8% (2013) to 8.6% (2014) to 12.3% (2015). The UK TAVI Registry demonstrates a pre-procedural permanent pacing bias amongst patients receiving transcatheter valves with higher post-procedure pacing rates. Pre-emptive permanent pacing is likely to be responsible for this difference.

Nonlinear Landau damping of plasma waves with orbital angular momentum.

We present, using three-dimensional particle-in-cell simulations, an observation that orbital angular momentum (OAM) is transferred to resonant electrons proportionally to longitudinal momentum when Laguerre-Gaussian plasma waves are subjected to Landau damping. A higher azimuthal mode number leads to a larger net orbital angular momentum transfer to particles traveling close to the phase velocity of the plasma wave, implying a population of electrons that are orbiting the same center of rotation as the plasma wave. This observation has implications on magnetic field excitation as a result of the formation and damping of OAM plasma waves. The energy distributions of electrons in damping Laguerre-Gaussian plasma waves are significantly changed as a function of azimuthal mode number. This leads to larger numbers of lower energy particles tending towards a significant narrowing of the energy distribution of accelerated particles.

Kinetic plasma waves carrying orbital angular momentum.

The structure of Langmuir plasma waves carrying a finite orbital angular momentum is revised in the paraxial approximation. It is shown that the kinetic effects related to higher-order momenta of the electron distribution function lead to coupling of Laguerre-Gaussian modes and result in a modification of the wave dispersion and damping. The theoretical analysis is compared to the three-dimensional particle-in-cell numerical simulations for a mode with orbital momentum l=2. It is demonstrated that propagation of such a plasma wave is accompanied with generation of quasistatic axial and azimuthal magnetic fields which result from the orbital and longitudinal momenta transported with the wave, respectively.

Micron-scale mapping of megagauss magnetic fields using optical polarimetry to probe hot electron transport in petawatt-class laser-solid interactions.

The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-µm thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~1020 W/cm2. The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

Permanent pacemaker insertion after CoreValve transcatheter aortic valve implantation: incidence and contributing factors (the UK CoreValve Collaborative).

BACKGROUND: Permanent pacemaker (PPM) requirement is a recognized complication of transcatheter aortic valve implantation. We assessed the UK incidence of permanent pacing within 30 days of CoreValve implantation and formulated an anatomic and electrophysiological model. METHODS AND RESULTS: Data from 270 patients at 10 centers in the United Kingdom were examined. Twenty-five patients (8%) had preexisting PPMs; 2 patients had incomplete data. The remaining 243 were 81.3±6.7 years of age; 50.6% were male. QRS duration increased from 105±23 to 135±29 milliseconds (P<0.01). Left bundle-branch block incidence was 13% at baseline and 61% after the procedure (P<0.001). Eighty-one patients (33.3%) required a PPM within 30 days. Rates of pacing according to preexisting ECG abnormalities were as follows: right bundle-branch block, 65.2%; left bundle-branch block, 43.75%; normal QRS, 27.6%. Among patients who required PPM implantation, the median time to insertion was 4.0 days (interquartile range, 2.0 to 7.75 days). Multivariable analysis revealed that periprocedural atrioventricular block (odds ratio, 6.29; 95% confidence interval, 3.55 to 11.15), balloon predilatation (odds ratio, 2.68; 95% confidence interval, 2.00 to 3.47), use of the larger (29 mm) CoreValve prosthesis (odds ratio, 2.50; 95% confidence interval, 1.22 to 5.11), interventricular septum diameter (odds ratio, 1.18; 95% confidence interval, 1.10 to 3.06), and prolonged QRS duration (odds ratio, 3.45; 95% confidence interval, 1.61 to 7.40) were independently associated with the need for PPM. CONCLUSION: One third of patients undergoing a CoreValve transcatheter aortic valve implantation procedure require a PPM within 30 days. Periprocedural atrioventricular block, balloon predilatation, use of the larger CoreValve prosthesis, increased interventricular septum diameter and prolonged QRS duration were associated with the need for PPM.

Primary percutaneous coronary intervention for acute ST elevation myocardial infarction--first year's experience of a tertiary referral centre in the UK.

This study evaluated the first year's experience of a large interventional centre in the UK after a primary percutaneous coronary intervention (PCI) programme that runs 24 hours a day and seven days a week was started. Workload, patient outcome, length of stay, and effect on the remainder of the interventional service were analysed. The primary PCI service for a mainly urban population of 800,000 was started in April 2005. All relevant characteristics, details of procedures, outcome, and other data on quality of care were collected and entered prospectively onto a computerised database. Data were analysed with SPSS (version 13.0). Over a 12-month period, 305 patients were diagnosed with ST elevation myocardial infarction (STEMI), of whom 259 (85%) were accepted for primary PCI. Median door-to-balloon time was 98 minutes, which decreased from 106 minutes in the first six months to 93 minutes in the second six months (p < 0.005). In-hospital mortality was 4.5% and 30-day mortality was 4.9%. Median length of stay was three days, which was reduced from the six days previously reported after thrombolysis. Waiting times for other acute and elective PCI procedures did not increase after initiation of the primary PCI programme. Primary PCI can be delivered successfully in a setting in the UK with low mortality and reduced length of stay and without a negative impact on other interventional services.

Semi-automatic boundary detection to improve reporting of regional left ventricular function.

AIMS: The reporting of regional left ventricular function is based on subjective assessment of endocardial motion and thickening and has a significant learning curve. We hypothesized that the use of an semi-automatic boundary detection system generating images with superimposed moving endocardial borders and a fixed end-diastolic reference border could improve the reporting of regional function. METHODS: We obtained 58 resting contrast images of 15 patients and using a new boundary detection system (Quamus), generated images with superimposed endocardial borders. The contrast images, images with additional Quamus borders and Quamus borders alone were assessed by two level 1 and two level 2 echocardiographers. They scored regional function and results were compared to two level 3 experienced stress echocardiography readers. RESULTS: The addition of borders improved the agreement of level 1 echocardiographers (weighted Kappa increased from 0.55 to 0.64) but did not change for level 2 echocardiographers (0.63 to 0.64) and has the potential to be a useful training tool.

Filter no reflow during percutaneous coronary interventions using the Filterwire distal protection device.

BACKGROUND: Distal protection devices are increasingly used to prevent embolization during percutaneous coronary interventions (PCI) in saphenous vein grafts (SVG) and native coronary arteries (NV). During interventions with the Filterwire device we have observed reduced flow that is reversible following removal of the filter (filter no reflow, FNR), which might be erroneously interpreted as true no reflow and might be associated with reduced capture efficiency of the basket. METHODS: We analyzed the incidence of FNR in 58 patients (60 lesions) at high risk of embolization undergoing PCI of either a SVG or a NV using the Filterwire (Boston Scientific, Natick, MA). Qualitative and quantitative angiographic analysis was performed, and the volume of collected debris was estimated using a photographic technique. RESULTS: In our population, about 1/3 of the cases showed FNR, which was associated with angiographically visible filling defects within the basket, indicating macroembolism. However some patients (especially those undergoing vein graft interventions) showed filling defects without FNR, and some others FNR without filling defects. Thus we tried to understand the predictors of FNR: FNR was associated with higher amount of collected debris (36.97 +/- 42.98 mm(3) vs. 11.31 +/- 18.47 mm(3), p = 0.005), was neither prevented by abciximab, nor predicted by high thrombotic burden, increasing stent volume or need for predilatation. When patient with and without angiographically evident macroembolisation were separately analyzed, a linear correlation of FNR with the quantity of debris was only apparent in the macroembolization group. CONCLUSIONS: Interventionalists should be aware of the "Filter No Reflow", a common but reversible angiographic complication when the Filterwire device is used. Reduced flow seen during these procedures should be treated conservatively. Mechanical obstruction of the filter, but also other mechanisms (pharmacologically active debris? platelet aggregates?) play a role in this phenomenon.

Towards a vulnerability assessment of the UK and northern European coasts: the role of regional climate variability.

Within the framework of a Tyndall Centre research project, sea level and wave changes around the UK and in the North Sea have been analysed. This paper integrates the results of this project. Many aspects of the contribution of the North Atlantic Oscillation (NAO) to sea level and wave height have been resolved. The NAO is a major forcing parameter for sea-level variability. Strong positive response to increasing NAO was observed in the shallow parts of the North Sea, while slightly negative response was found in the southwest part of the UK. The cause of the strong positive response is mainly the increased westerly winds. The NAO increase during the last decades has affected both the mean sea level and the extreme sea levels in the North Sea. The derived spatial distribution of the NAO-related variability of sea level allows the development of scenarios for future sea level and wave height in the region. Because the response of sea level to the NAO is found to be variable in time across all frequency bands, there is some inherent uncertainty in the use of the empirical relationships to develop scenarios of future sea level. Nevertheless, as it remains uncertain whether the multi-decadal NAO variability is related to climate change, the use of the empirical relationships in developing scenarios is justified. The resulting scenarios demonstrate: (i) that the use of regional estimates of sea level increase the projected range of sea-level change by 50% and (ii) that the contribution of the NAO to winter sea-level variability increases the range of uncertainty by a further 10-20cm. On the assumption that the general circulation models have some skill in simulating the future NAO change, then the NAO contribution to sea-level change around the UK is expected to be very small (<4cm) by 2080. Wave heights are also sensitive to the NAO changes, especially in the western coasts of the UK. Under the same scenarios for future NAO changes, the projected significant wave-height changes in the northeast Atlantic will exceed 0.4m. In addition, wave-direction changes of around 20 degrees per unit NAO index have been documented for one location. Such changes raise the possibility of consequential alteration of coastal erosion.

Determinants of platelet responsiveness to nitric oxide in patients with chronic heart failure.

Congestive heart failure (CHF) is associated with oxidative stress. Platelet responsiveness to nitric oxide (NO) donors, are impaired in patients with angina pectoris, possibly by increasing oxidative stress. We investigated the occurrence of platelet resistance to NO in patients, with ischaemic or non-ischaemic cardiomyopathy compared with normal subjects. Anti-aggregatory effects of sodium nitroprusside (SNP), oxidative stress and whole blood superoxide anion content were determined, with correlates of responsiveness to SNP. Inhibition of platelet aggregation by SNP was 65.4+/-3.55% in controls and 59.3+/-4.1% in CHF (P=ns) despite increased oxidative stress and post-aggregation O2- in CHF patients. However, subsets of CHF patients have NO-resistant platelets: this is associated with increasing age and/or increased oxidative stress (both p<0.05).

General anaesthesia in a patient with Brugada syndrome.

The successful administration of a combined general and epidural anaesthetic to a patient with Brugada syndrome is reported. A review of the literature is presented.

Self-reported Papanicolaou smears and hysterectomies among women in the United States.

OBJECTIVE: To evaluate the potential overuse of Papanicolaou smears among women who have had a hysterectomy. METHODS: We analyzed two surveys of US women aged 18 years or older, the Behavioral Risk Factor Surveillance System (1992-1997) and the National Health Interview Survey (1993-1994), and one survey of US hospitals (National Hospital Discharge Survey, 1980-1997). We examined the number of women who have had a hysterectomy who had a recent (within 3 years) Papanicolaou smear. We also examined trends in the proportions and rates of hysterectomies by diagnoses and type of procedure that potentially could require a Papanicolaou smear. RESULTS: From the Behavioral Risk Factor Surveillance System, an estimated 21.2% of US women have had a hysterectomy. Among women who have had a hysterectomy, 78.3% had a recent Papanicolaou smear. Among those reporting no hysterectomy, 82.1% had a recent Papanicolaou smear. Estimates from the National Health Interview Survey were similar. From the National Hospital Discharge Survey, an estimated 6.7% to 15.4% of women with a history of hysterectomy would require a subsequent Papanicolaou smear because they had a diagnosis related to cervical neoplasia or because they had undergone a supracervical hysterectomy. For an estimated 10.6-11.6 million of the 12.5 million women who had a hysterectomy and a recent Papanicolaou smear, that test could be considered unnecessary. CONCLUSION: Continued Papanicolaou screening of women without an intact uteri may result in excessive use of resources in time and money with minimal impact on decreasing cervical cancer.

A statewide analysis of level I and II trauma centers for patients with major injuries.

BACKGROUND: This study examines statewide outcomes and resource use in Level I and II trauma centers for patients with major injuries. METHODS: This study analyzed trauma registry data on patients admitted to North Carolina Level I and II trauma centers from January 1995 to December 1996 with one of four major injuries: thoracic aortic disruption, liver injury, pelvic fracture, or pulmonary contusion. RESULTS: There were 59 thoracic aortic disruptions, 109 liver injuries, 153 pelvic fractures, and 962 pulmonary contusions identified among 26,030 admissions. Case fatality was not significantly different (Level I, 16.8%; Level II, 14.9%). Hospital charges were significantly higher in Level I centers (Level I, $47,366; Level II, $35,490), but this difference was confined to transferred patients. Controlling for Revised Trauma Score, Injury Severity Score, age, gender, and race, multivariable regression confirmed findings regarding hospital charges, and multiple logistic regression confirmed findings regarding case fatality. CONCLUSION: Case fatality was similar in Level I and Level II trauma centers in North Carolina, and hospital charges were comparable in patients with comparable injuries not requiring transfer. This suggests that patients with major injuries may be optimally cared for in both Level I and Level II trauma centers.

An off-axis hydrothermal vent field near the Mid-Atlantic Ridge at 30 degrees N.

Evidence is growing that hydrothermal venting occurs not only along mid-ocean ridges but also on old regions of the oceanic crust away from spreading centres. Here we report the discovery of an extensive hydrothermal field at 30 degrees N near the eastern intersection of the Mid-Atlantic Ridge and the Atlantis fracture zone. The vent field--named 'Lost City'--is distinctly different from all other known sea-floor hydrothermal fields in that it is located on 1.5-Myr-old crust, nearly 15 km from the spreading axis, and may be driven by the heat of exothermic serpentinization reactions between sea water and mantle rocks. It is located on a dome-like massif and is dominated by steep-sided carbonate chimneys, rather than the sulphide structures typical of 'black smoker' hydrothermal fields. We found that vent fluids are relatively cool (40-75 degrees C) and alkaline (pH 9.0-9.8), supporting dense microbial communities that include anaerobic thermophiles. Because the geological characteristics of the Atlantis massif are similar to numerous areas of old crust along the Mid-Atlantic, Indian and Arctic ridges, these results indicate that a much larger portion of the oceanic crust may support hydrothermal activity and microbial life than previously thought.