P2831Safety of atrial fibrillation catheter ablation in the elderly

Background

Catheter ablation for drug refractory, symptomatic atrial fibrillation (AF), is becoming increasingly common and can be beneficial in alleviating symptoms. However, in the elderly, there are concerns about the risks an invasive procedure poses, with limited published data available in those aged over 80 years.

Purpose

To determine the complication risk of AF catheter ablation in the elderly

Methods

Complications were identified from patient records in 3156 consecutive patients who underwent radiofrequency catheter ablation for AF, at a tertiary cardiology centre between 2013–2017. All cases were performed under general anesthesia.

Results

In this cohort of 3156 patients (mean age= 62.9±11.0 years, female = 29.9%), 90 (2.85%) (mean age= 66±10.0 years, female = 49.5%) complications were identified. In patients aged ≥80 years, complications occurred in 5 out of 99 patients (5.05%) (mean age= 82.6±1.2, female=100%), compared to 85 out of 3057 patients (2.78%) in those aged <80 years (mean age= 65±10.3, female = 49.4%). The difference was not significant p=0.18. Complications in the elderly all occurred acutely, and included groin haematoma (2.02%), pneumonia (2.02%) and pericardial effusion (1.01%).

Conclusion

Catheter ablation for AF in patients ≥80 years of age, is not associated with a significant increase in complication risk, compared to those who are younger.

Extraction of the ^{235}U and ^{239}Pu Antineutrino Spectra at Daya Bay

This Letter reports the first extraction of individual antineutrino spectra from ^{235}U and ^{239}Pu fission and an improved measurement of the prompt energy spectrum of reactor antineutrinos at Daya Bay. The analysis uses 3.5×10^{6} inverse beta-decay candidates in four near antineutrino detectors in 1958 days. The individual antineutrino spectra of the two dominant isotopes, ^{235}U and ^{239}Pu, are extracted using the evolution of the prompt spectrum as a function of the isotope fission fractions. In the energy window of 4-6 MeV, a 7% (9%) excess of events is observed for the ^{235}U (^{239}Pu) spectrum compared with the normalized Huber-Mueller model prediction. The significance of discrepancy is 4.0σ for ^{235}U spectral shape compared with the Huber-Mueller model prediction. The shape of the measured inverse beta-decay prompt energy spectrum disagrees with the prediction of the Huber-Mueller model at 5.3σ. In the energy range of 4-6 MeV, a maximal local discrepancy of 6.3σ is observed.

An Introductory Guide to Survey Research in Anaesthesia

Surveys allow convenient and inexpensive research. Surveys include mail-out questionnaires, email questionnaires, telephone interviews, and personal interviews. Despite a widespread perception that surveys are easy to conduct, good surveys need rigorous design, implementation and analysis. This requires substantial planning, time and effort. The most important step in designing a survey is to clearly define the question (s) the survey aims to answer. The target population, measured variables and types of associations being investigated should be specific and unambiguous. Investigators should concentrate on what they ‘need to know’ rather than what would be ‘nice to know’. During development surveys should be piloted to identify problems. The main goal when implementing a survey is to maximize the response rate to avoid misleading results. Evidence-based strategies, including brief personalized surveys with stamped return envelopes, can be used to maximize the response rate. A poorly conducted survey can lead to misleading or invalid conclusions and may undermine participation in subsequent surveys by the target population.

Serotonin Syndrome and the Anaesthetist

Serotonin syndrome results from excessive activation of serotonin (5-hydroxytryptamine; 5-HT) receptors in the nervous system, on the surface of platelets, and on the vascular endothelium. The clinical manifestations are a triad of altered conscious state, autonomic dysfunction, and neuromuscular excitability. Clinical diagnostic criteria remain poorly defined and unvalidated, and there are no available investigations to confirm the diagnosis. The syndrome is caused by the administration of one or more drugs possessing serotonergic activity. Severe forms of the syndrome usually result from overdose, but can be induced by monotherapy. The exact incidence of serotonin syndrome remains unknown, but is likely to be increasing due to increased prescription of selective serotonin reuptake inhibitor anti-depressants and tramadol, as well as recreational use of amphetamine-like substances. Serotonin syndrome may complicate the administration of drugs frequently used in anaesthetic practice, including pethidine and tramadol. Although the majority of cases improve with symptomatic and supportive care, severe cases need intensive care and frequently require mechanical ventilation. Neuromuscular excitability is likely to be the cause of rhabdomyolysis seen in severe cases and should be treated with benzodiazepines and muscle relaxants. Supportive therapies are required to treat hyperthermia and autonomic dysfunction. Cyproheptadine is the most commonly administered serotonergic antagonist, but is unavailable in parenteral form.

Perioperative Pulse Contour Cardiac Output Analysis in a Patient with Severe Cardiac Dysfunction

We describe a patient with severe left ventricular dysfunction simultaneously monitored with pulse contour cardiac output (PiCCO) analysis, a continuous cardiac output pulmonary artery catheter (continuous COPAC) and intraoperative transoesophageal echocardiography (TOE).

There was good agreement between cardiac output (CO) measurements obtained by the three techniques prior to cardiopulmonary bypass (CPB). Agreement of CO measurements following CPB was initially poor, but improved following recalibration of PiCCO.

PiCCO-derived global end-diastolic volume index (GEDVI) and cardiac function index (CFI), were assessed as markers of left ventricular preload and myocardial contractility, respectively. GEDVI correlated well with CO in the postoperative period.

CFI increased more than two -fold following coronary revascularization and milrinone administration, and there was also a temporal relationship between the CFI and the dose of milrinone in the first 24 hours of treatment.

Global end-diastolic volume and cardiac function index may be useful additional measures of left ventricular preload and myocardial contractility in patients with severe left ventricular dysfunction.

Measurement of the Electron Antineutrino Oscillation with 1958 Days of Operation at Daya Bay

We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor ν[over ¯]_{e} inverse β decay candidates observed over 1958 days of data collection. The installation of a flash analog-to-digital converter readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic ^{9}Li and ^{8}He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative ν[over ¯]_{e} rates and energy spectra among detectors yields sin^{2}2θ_{13}=0.0856±0.0029 and Δm_{32}^{2}=(2.471_{-0.070}^{+0.068})×10^{-3}  eV^{2} assuming the normal hierarchy, and Δm_{32}^{2}=-(2.575_{-0.070}^{+0.068})×10^{-3}  eV^{2} assuming the inverted hierarchy.