Pulse oximeter plethysmograph waveform and automated oscillometric sphygmomanometer for ankle-brachial index measurement.

OBJECTIVES: There are limited non-invasive methods to assess lower extremity arterial injuries in the emergency department (ED) and pre-hospital setting. The ankle-brachial index (ABI) requires careful auscultation by Doppler, an approach made difficult in noisy environments. We sought to determine the agreement of the ABI measured using the pulse oximeter plethysmograph waveform (Pleth) with auscultation by Doppler in a controlled setting. A secondary outcome sought to examine the agreement of ABI by automated oscillometric sphygmomanometer (AOS) with Doppler. METHODS: We measured blood pressure in the right upper and lower extremities of healthy volunteers using: (1) Doppler and manual sphygmomanometer; (2) Pleth and manual sphygmomanometer; and (3) AOS. The Bland-Altman approach to assessing agreement between methods was used comparing mean differences between ABI pairs to their means for Doppler versus Pleth and Doppler versus AOS. The intraclass correlation coefficient (ICC) from mixed effects models examined intra- and inter-rater reliability. RESULTS: Among 100 participants with normal ABI the mean ABI (95%CI) were Doppler 1.11 (0.90-1.33), Pleth 1.10 (0.91-1.30), and AOS 1.10 (0.90-1.30). The ABI difference (95% CI for limits of agreement) were 0.01 (-0.20,0.18) for Doppler-Pleth and 0.02 (-0.26, 0.22) for Doppler-AOS. The ICC for the Doppler-Pleth comparison (ICC = 0.56, 95% CI 0.47-0.63) was greater than for the Doppler-AOS (ICC = 0.32, 95% CI 0.19-0.43). CONCLUSIONS: The ABI measured using the Pleth has a high level of agreement with measurement by Doppler. The AOS and Doppler have good agreement with greater measurement variability. Pleth and AOS may be reasonable alternatives to Doppler for ABI.

Deglutition-Induced Atrial Tachycardia Localised with Contact Force-Guided Activation Mapping.

Deglutition-induced atrial tachycardia is a rare arrhythmia with a poor response to medical therapy. Electrophysiological study is challenging due to the dependence of induction on swallowing. We present a novel approach to management of deglutition-induced atrial tachycardia arising from right superior pulmonary vein. Use of minimal conscious sedation and repeated swallow challenge inductions, together with contact force-guided mapping were key determinants of success. We review published cases, discussing potential mechanisms including oesophageal distension and neural reflexes.

Characterization of domestic wastewater released from 'green' households and field study of the performance of onsite septic tanks retrofitted into aerobic bioreactors in cold climate.

This study aimed to investigate the efficacy of private septic systems retrofitted into aerobic bioreactors with 'SludgeHammer' technology. In addition, the study attempted to characterize the strength of domestic wastewater released from 'green' households practicing water conservation strategies. Ten retrofitted onsite septic systems were studied in the Edmonton area, Alberta (AB) Canada during winter. These systems could remove BOD5 and TSS by 92 ± 5 and 92 ± 6% respectively which, according to Albertan regulatory standards, were characteristic removal efficiencies of the secondary treatment in the subsequent drain field. These removal efficiencies were remarkable given the strength of the influent wastewater. The raw wastewater carried significantly high pollutant concentrations (1160 ± 350 mg BOD5/L, 1653 ± 1174 mg TSS/L, 99 ± 19 mg NH4+-N/L, 100 ± 56 mg TN/L, and 39 ± 28 mg PO43--P/L), characterizing it as high-strength domestic wastewater. Mixing provided by the aerator could only suspend 1/34th (3% m/m) of the solids in the bioreactor and consequently released significantly low solid concentrations (195 ± 206 mg TSS/L) into the final treatment component. As such, this technology did not impair the natural function of septic tanks or did not create any unintended excessive solid loading on drain field as a consequence of the added mixing energies provided by the active aeration. Nitrogen balance suggested the possibility of simultaneous nitrification and denitrification (SND) in the aerobic bioreactors. In some cases, PO43--P removal efficiency was as high as that in enhanced biological phosphate removal (EBPR) process (81-97%). Phosphorus balance estimated that non-assimilative pathways (i.e., EBPR + biologically induced phosphate precipitation (BIPP)) contributed 50-99% to overall phosphorus removal in the system. Long HRTs, high influent BOD5 and anaerobic/aerobic zoning in the bioreactor most likely provided favorable conditions for SND and high phosphorus removal efficiencies in the retrofitted onsite wastewater treatment systems (OWTS).

Atrial Remodeling Following Catheter Ablation for Atrial Fibrillation-Mediated Cardiomyopathy: Long-Term Follow-Up of CAMERA-MRI Study.

OBJECTIVES: This study sought to determine the long-term right atrial (RA) electrical and structural changes in a subgroup from the CAMERA-MRI (Catheter Ablation Versus Medical Rate Control in Atrial Fibrillation and Systolic Dysfunction-Magnetic Resonance Imaging) study. BACKGROUND: Catheter ablation (CA) is successful in restoring ventricular function in patients with atrial fibrillation (AF) and otherwise unexplained cardiomyopathy, as demonstrated in the randomized study of CA versus rate control (CAMERA-MRI). It is unknown if this is associated with atrial remodeling. METHODS: Detailed electroanatomical (EA) mapping of the RA using CARTO3 and a force sensing catheter was performed at initial CA and electively at least 12 months after CA in patients with >90% reduction in AF burden following ablation. Bipolar voltage, fractionation, and conduction velocity were collected in 4 segments together with echo and cardiac magnetic resonance imaging. RESULTS: Fifteen patients (mean age 59.1 ± 6.8 years) underwent repeat RA EA mapping. At a mean follow-up of 23.4 ± 11.9 months, left ventricular (LV) ejection fraction improved from 33.6 ± 3.2% to 54.1 ± 3.2% (p = 0.001), RA area decreased from 28.4 ± 2.0 cm2 to 20.8 ± 1.2 cm2 (p < 0.001), and left atrial area decreased from 32.9 ± 2.3 cm2 to 26.8 ± 1.4 cm2 (p = 0.007). On EA mapping, RA bipolar voltage increased from 1.6 ± 0.1 mV to 1.9 ± 0.1 mV (p = 0.04). Tissue voltage increased across all regions, which achieved statistical significance at the posterior (p = 0.002) and septal (p = 0.01) segments. There was a significant decrease in complex fractionated electrograms from 21.7 ± 3.5% to 8.3 ± 1.8% (p = 0.002); however, no significant change occurred in global or regional conduction velocities (p = 0.5). CONCLUSIONS: Recovery of atrial electrical and structural changes was observed following restoration of sinus rhythm and recovery of LV function in patients who underwent CA for persistent AF and LV systolic dysfunction. The randomized CAMERA MRI study demonstrated significant improvement in LV systolic function with AF ablation compared with rate control. The present study demonstrated reverse electrical and structural atrial recovery in concert with recovery of LV systolic function at 2 years post-AF ablation. This may partially explain the long-term success of CA in patients with AF and otherwise unexplained cardiomyopathy.

A novel criterion for conduction block after catheter ablation of right atrial tachycardia after mitral valve surgery.

BACKGROUND: One operative approach to the mitral valve, the superior transseptal incision, is proarrhythmic because of extensive atriotomies. The objective of this study is to describe complex atrial tachycardias (ATs) that occur after this approach and propose methods to verify lines of block as an end point for catheter ablation. METHODS AND RESULTS: Of the 69 patients who had electrophysiological studies for AT after mitral valve surgery, 20 patients had prior superior transseptal incisions. Of these, 14 had complex ATs involving the lateral right atrium (RA). There were 9 dual-loop, 4 single-loop, and 1 focal tachycardias. Lateral wall ablation was performed either by creating a linear lesion from the lateral atriotomy to the inferior vena cava, superior vena cava, or tricuspid annulus or by ablating focally in the lateral RA. After a single ablation procedure, conduction block in the lateral wall was verified in 10 of 14 patients using 1 of 2 distinct patterns of block. One pattern consisted of late activation in an anterolateral corridor of the RA, and a second pattern consisted of wide-spaced double potentials. Recurrent conduction through the lateral wall lesions was associated with intraprocedural and late recurrences of ATs. CONCLUSIONS: The optimal end point for ablating ATs after mitral valve surgery with the superior transseptal approach is to establish lines of block that can be recognized by characteristic patterns of activation in the lateral RA. A novel criterion for lateral conduction block after catheter ablation is identification of a late-activated corridor in the anterolateral RA.