The U wave in atrial fibrillation

The U wave in ECGs of patients is difficult to observe because it is hidden under the atrial fibrillatory wave. Measurement and characteristics of the U wave in atrial fibrillation have not previously been described. Beat averaging was used to reveal the U waves in 12-lead ECGs of 8 patients with atrial fibrillation taking account of heart rate dependency of U wave characteristics. U wave polarity and amplitude in 12-lead ECG and the amplitude ratio of U wave to atrial fibrillatory wave in lead VI were measured. U waves were measureable in all patients. U waves were predominantly positive in leads 1. 11. aVF. V2. V3, V4, V5 and V6, negative in leads aVR. Amplitudes were largest in the precordial leads measuring up to 55 fJ V. In lead VI the U wave amplitude was on average 0.17 (range 0.1 to 0.4) times the amplitude of the atrial fibrillatory wave. U waves can be measured by ventricular beat averaging in AF patients. U waves were normal in this small group of patients

Recurring patterns of atrial fibrillation in surface ECG predict restoration of sinus rhythm by catheter ablation

Background Non-invasive tools to help identify patients likely to benefit from catheter ablation (CA) of atrial fibrillation (AF) would facilitate personalised treatment planning. Aim To investigate atrial waveform organisation through recurrence plot indices (RPI) and their ability to predict CA outcome. Methods One minute 12-lead ECG was recorded before CA from 62 patients with AF (32 paroxysmal AF; 45 men; age 57±10 years). Organisation of atrial waveforms from i) TQ intervals in V1 and ii) QRST suppressed continuous AF waveforms (CAFW), were quantified using RPI: percentage recurrence (PR), percentage determinism (PD), entropy of recurrence (ER). Ability to predict acute (terminating vs. non-terminating AF), 3-month and 6-month postoperative outcome (AF vs. AF free) were assessed. Results RPI either by TQ or CAFW analysis did not change significantly with acute outcome. Patients arrhythmia-free at 6-month follow-up had higher organisation in TQ intervals by PD (

Effect of catheter ablation on quality of life in patients with atrial fibrillation and its correlation with arrhythmia outcome

Objective To assess the effect of catheter ablation on atrial fibrillation (AF) symptoms and quality of life (QoL). Methods Patients with AF scheduled for ablation were recruited. Pulmonary vein isolation (PVI) was performed and complex fractionated atrial electrogram (CFAE)±linear ablation undertaken in patients in AF despite PVI. QoL and AF symptoms were assessed using SF-36 V2 and Atrial Fibrillation Effect on Quality-of-Life (AFEQT) questionnaires before and 3 months after ablation. Change in QoL scores after ablation was correlated with clinical parameters and the extent of ablation. Magnitude of QoL change was compared between AFEQT and SF-36 physical component summary (PCS) and mental component summary (MCS) scores and correlated with arrhythmia outcome. Results 80 patients were studied. Summative and individual health scores for both AFEQT (51.5±22.0 vs 81.3±18.2; p<0.01) and SF-36 (PCS 43.3±10.5 vs 47.9±11.3; p<0.01 and MCS 45.0±11.5 vs 51.5±9.4; p<0.01) improved significantly in patients who maintained sinus rhythm after ablation, but not in those with recurrent AF. Improvement in AFEQT (25.4±19) was significantly greater than change in PCS (6.8±6.4; p<0.01) and MCS (8.5±7.9; p<0.01) scores and correlated more closely with arrhythmia outcome (AFEQT r=0.55; PCS r=0.26; MCS r=0.30). Conclusions Patients who maintained sinus rhythm after ablation had a significant improvement in AF symptoms and QoL; however, no improvement was observed in patients with recurrent AF. QoL change after ablation did not correlate with baseline clinical parameters or ablation strategy. AF specific QoL scales are more responsive to change and correlate better with ablation outcome

Principal component analysis of atrial fibrillation: Inclusion of posterior ECG leads does not improve correlation with left atrial activity

Background Lead V? is routinely analysed due to its large amplitude AF waveform. V? correlates strongly with right atrial activity but only moderately with left atrial activity. Posterior lead V? correlates strongest with left atrial activity. Aims (1) To establish whether surface dominant AF frequency (DAF) calculated using principal component analysis (PCA) of a modified 12-lead ECG (including posterior leads) has a stronger correlation with left atrial activity compared to the standard ECG. (2) To assess the contribution of individual ECG leads to the AF principal component in both ECG configurations. Methods Patients were assigned to modified or standard ECG groups. In the modified ECG, posterior leads V? and V? replaced V? and V?. AF waveform was extracted from one-minute surface ECG recordings using PCA. Surface DAF was correlated with intracardiac DAF from the high right atrium (HRA), coronary sinus (CS) and pulmonary veins (PVs). Results 96 patients were studied. Surface DAF from the modified ECG did not have a stronger correlation with left atrial activity compared to the standard ECG. Both ECG configurations correlated strongly with HRA, CS and right PVs but only moderately with left PVs. V? contributed most to the AF principal component in both ECG configurations

The Profitability of Chinese banks: impacts of risk, competition and efficiency

Purpose: This study aims to test the impacts of risk-taking behaviour, competition and cost efficiency on bank profitability in China. Design/methodology/approach: A two-step generalized method of moments system estimator is used to examine the impacts of risk, competition and cost efficiency on profitability of a sample of Chinese commercial banks over the period 2003-2013. Findings: The paper finds that credit risk, liquidity risk, capital risk, security risk and insolvency risk significantly influence the profitability of Chinese commercial banks. To be more specific, credit risk is significantly and negatively related to bank profitability; liquidity risk is significantly and positively related to return on assets (ROA) and net interest margin (NIM) but negatively related to return on equity (ROE); capital risk has a significant and negative impact on ROA and NIM but a positive impact on ROE; there is a significant and negative impact of security risk on bank profitability (ROA and NIM). It is found that Chinese commercial banks with higher levels of insolvency risk have higher profitability (ROA and ROE). Finally, higher competition leads to lower profitability in the Chinese banking industry, and Chinese commercial banks with higher levels of cost efficiency have lower ROA. In other words, the structure–conduct–performance paradigm rather than the efficient–structure paradigm holds in the Chinese banking industry. Originality/value: This is the first paper to investigate the impact of different types of risk, including credit risk, liquidity risk, capital risk, security risk and insolvency risk, on bank profitability. This is the first study which uses more accurate measurements of efficiency and competition compared to previous Chinese banking profitability literature and which tests their impact on bank profitability. The findings not only provide a general picture on the risk, efficiency and competition conditions in the Chinese banking industry, but also give valuable information to the Chinese Government and to the banking regulatory authorities to make relevant policies

The Envelope Kinematics and a Possible Disk Around the Class 0 Protostar within BHR7

We present a characterization of the protostar embedded within the BHR7 dark cloud, based on both photometric measurements from the near-infrared to millimeter and interferometric continuum and molecular line observations at millimeter wavelengths. We find that this protostar is a Class 0 system, the youngest class of protostars, measuring its bolometric temperature to be 50.5~K, with a bolometric luminosity of 9.3~L$_{\odot}$. The near-infrared and \textit{Spitzer} imaging show a prominent dark lane from dust extinction separating clear bipolar outflow cavities. Observations of $^{13}$CO ($J=2\rightarrow1$), C$^{18}$O ($J=2\rightarrow1$), and other molecular lines with the Submillimeter Array (SMA) exhibit a clear rotation signature on scales $<$1300~AU. The rotation can be traced to an inner radius of $\sim$170~AU and the rotation curve is consistent with an R$^{-1}$ profile, implying that angular momentum is being conserved. Observations of the 1.3~mm dust continuum with the SMA reveal a resolved continuum source, extended in the direction of the dark lane, orthogonal to the outflow. The deconvolved size of the continuum indicates a radius of $\sim$100~AU for the continuum source at the assumed distance of 400~pc. The visibility amplitude profile of the continuum emission cannot be reproduced by an envelope alone and needs a compact component. Thus, we posit that the resolved continuum source could be tracing a Keplerian disk in this very young system. If we assume that the continuum radius traces a Keplerian disk (R$\sim$120~AU) the observed rotation profile is consistent with a protostar mass of 1.0~$M_{\odot}$.Comment: 36 pages; 11 Figures, 2 Tables; Accepted to Ap

Surgical procedure for the cure of atrioventricular junctional (“AV node”) reentrant tachycardia: Anatomic and electrophysiologic effects of dissection of the anterior atrionodal connections in a canine model

AbstractObjectives. This study was undertaken to examine the electrophysiologic and anatomic efects of a surgical procedure that cures the anterior (common) type of atrioventricular (AV) junciional reentrant tachycardia.Background. The procedure was designed to interrupt the reentrant circuit at the point of earliest atrial activation during AV junctional reentrant tachycardia, the anterior atrionodal connections.Methods. Atrioventricular node function and the sequence of electrical excitation of Koch's triangle were examined in 18 dogs. Excitation of Koch's triangle was mapped using a 60-channel mapping system. Surgical dissection was performed in 10 dogs and a sham procedure in 8. After 28 to 35 days, AV node function and the atrial excitation pattern were reassessed. The AV junction was examined using light microscopy.Results. Some degree of AV node damage was visible in all dogs in the dissection group, but it was minor in 40% of cases. The anterior part of the AV node was disconnected from the anterior atrionodal connections in all cases. Anterograde AV node function was mildly impaired. The median AH interval was increased (62 vs. 76 ms [interquartile ranges 48 to 72 and 64 to 104, respectively], P = 0.05), and the AV Wenckebach cycle length was increased (210 vs. 245 ms [interquartile ranges 200 to 230 and 210 to 260, respectively], p = 0.02). The degree of impairment of conduction was directly proportional to the length of dissection (p < 0.05) but not to the degree of damage to the AV node. Ventriculoatrial (VA) conduction was destroyed in 50% of dogs undergoing dissection but in none of those with a sham operation (p < 0.04). The AV node remained responsive to autonomic blocking drugs, and atrial mapping during ventricular pacing revealed that the site of exit from the AV node had been altered.Conclusions. The atrionodal connections closest to the His bundle are the preferred route of conduction through the AV node during normal AV or VA conduction. Destruction of these connections modifies AV node conduction. The surgical procedure selectively interrupts these connections, and this interruption is likely to be the mechanism of cure

Telehealth in remote Australia : a supplementary tool or an alternative model of care replacing face-to-face consultations?

Background: The COVID-19 pandemic increased the use of telehealth consultations by telephone and video around the world. While telehealth can improve access to primary health care, there are significant gaps in our understanding about how, when and to what extent telehealth should be used. This paper explores the perspectives of health care staff on the key elements relating to the effective use of telehealth for patients living in remote Australia. Methods: Between February 2020 and October 2021, interviews and discussion groups were conducted with 248 clinic staff from 20 different remote communities across northern Australia. Interview coding followed an inductive approach. Thematic analysis was used to group codes into common themes. Results: Reduced need to travel for telehealth consultations was perceived to benefit both health providers and patients. Telehealth functioned best when there was a pre-established relationship between the patient and the health care provider and with patients who had good knowledge of their personal health, spoke English and had access to and familiarity with digital technology. On the other hand, telehealth was thought to be resource intensive, increasing remote clinic staff workload as most patients needed clinic staff to facilitate the telehealth session and complete background administrative work to support the consultation and an interpreter for translation services. Clinic staff universally emphasised that telehealth is a useful supplementary tool, and not a stand-alone service model replacing face-to-face interactions. Conclusion: Telehealth has the potential to improve access to healthcare in remote areas if complemented with adequate face-to-face services. Careful workforce planning is required while introducing telehealth into clinics that already face high staff shortages. Digital infrastructure with reliable internet connections with sufficient speed and latency need to be available at affordable prices in remote communities to make full use of telehealth consultations. Training and employment of local Aboriginal staff as digital navigators could ensure a culturally safe clinical environment for telehealth consultations and promote the effective use of telehealth services among community members