Biological and chemical treatment technologies for waste amines from CO2 capture plants.

Amine-based carbon dioxide capture is the most mature technology for reducing flue gas CO2 emissions. It has been postulated and observed during commercialisation of this technology that significant quantities of waste amines are produced. Further industrial implementation of this technology requires adequate disposal or valorisation options for this waste. This review presents an analysis of seven biological and chemical technologies for waste amine amelioration or valorisation. Of these, the biological treatments are identified as being more mature for industrial application with the capacity for marketable product generation. Slow speed is the main drawback of the biological processes but this does not hinder their commercial viability. Using waste amine for NOx reduction in power stations is a secondary option, where it seems probable that the amount of waste amine generated in the CO2 capture plant is sufficient to fulfil the DeNOx requirements of the flue gas. This route, however, requires investigation into the impact of waste amine impurities on the power station and the CO2 capture plant operations.

Towards commercial scale postcombustion capture of CO2 with monoethanolamine solvent: key considerations for solvent management and environmental impacts.

Chemical absorption with aqueous amine solvents is the most advanced technology for postcombustion capture (PCC) of CO(2) from coal-fired power stations and a number of pilot scale programs are evaluating novel solvents, optimizing energy efficiency, and validating engineering models. This review demonstrates that the development of commercial scale PCC also requires effective solvent management guidelines to ensure minimization of potential technical and environmental risks. Furthermore, the review reveals that while solvent degradation has been identified as a key source of solvent consumption in laboratory scale studies, it has not been validated at pilot scale. Yet this is crucial as solvent degradation products, such as organic acids, can increase corrosivity and reduce the CO(2) absorption capacity of the solvent. It also highlights the need for the development of corrosion and solvent reclamation technologies, as well as strategies to minimize emissions of solvent and degradation products, such as ammonia, aldehydes, nitrosamines and nitramines, to the atmosphere from commercial scale PCC. Inevitably, responsible management of aqueous and solid waste will require more serious consideration. This will ultimately require effective waste management practices validated at pilot scale to minimize the likelihood of adverse human and environmental impacts from commercial scale PCC.

Influence of detomidine on atrial fibrillation cycle length measured by intracardiac electrogram recording and by colour tissue Doppler imaging in horses.

REASONS FOR PERFORMING STUDY: Shortening of atrial fibrillation cycle length (AFCL) is a marker of atrial electrical remodelling due to atrial fibrillation (AF). OBJECTIVES: To investigate the effect of administration of detomidine on AFCL measured invasively from an intra-atrial electrogram (AFCLEGM) and noninvasively by tissue Doppler imaging (AFCLTDI). We hypothesised that detomidine would have no effect on AFCL but would improve the ease of TDI measurements and facilitate noninvasive AFCL determination. STUDY DESIGN: Prospective clinical study. METHODS: Measurements were performed before and after i.v. administration of 7.5 µg/kg bwt detomidine in 33 episodes of AF in 32 horses (582 ± 64 kg bwt, 10 ± 3 years old) referred for electrical cardioversion. The AFCLEGM was measured from a right atrial intracardiac electrogram. The AFCLTDI was measured from atrial colour tissue velocity curves in 5 atrial wall regions. Mean AFCLEGM and AFCLTDI without and with sedation were compared using a repeated-measures linear mixed model with Bonferroni correction for multiple comparisons and calculation of the Bland-Altman mean bias and limits of agreement between AFCLEGM and AFCLTDI. RESULTS: The mean AFCL was significantly increased after sedation, but this increase was very small (mean difference +4 ms). For AFCLTDI measurements, sedation significantly improved the quality of the atrial myocardial velocity curves and the number of AF cycles that could be measured per cardiac cycle. The Bland-Altman bias between AFCLEGM without sedation and AFCLTDI with sedation ranged from -18 to +15 ms depending on wall region. Bland-Altman limits of agreement were similar between AFCLEGM without sedation and AFCLTDI without and with sedation. Therefore, noninvasive AFCLTDI measurements with sedation can be used to estimate the atrial fibrillatory rate. CONCLUSIONS: Sedation facilitates noninvasive AFCL measurements but causes a slight increase in AFCL. Noninvasive AFCL measurements can be used as an indicator of atrial electrical remodelling, to study AF pathophysiology and to investigate the effect of anti-arrhythmic drugs.

Atrial Premature Depolarization-Induced Changes in QRS and T Wave Morphology on Resting Electrocardiograms in Horses.

BACKGROUND: The electrocardiographic differentiation between atrial (APDs) and ventricular (VPDs) premature depolarizations is important. P wave prematurity and normal QRS and T wave morphology generally are used as discriminating criteria for APDs. HYPOTHESIS/OBJECTIVES: The aim of this study was to determine whether P, Q, R, S, and T wave amplitude, PQ interval, QRS and P wave duration and P and T wave morphology differ between APDs and sinus beats. To determine the relationship between the RR coupling interval and the change in S wave amplitude between sinus beats and APDs. METHODS: Case-control study. From a modified base-apex configuration of 30 horses with APDs at rest, sinus beat and APD associated preceding RR interval, P, PQ and QRS duration and P, R, S, and T wave amplitudes were measured. Linear mixed models and logistic regression were used to determine the effect of APDs on the ECG variables studied. RESULTS: In comparison to sinus beats, APDs were associated with a significant (P < .001) change in P amplitude (-0.03 ± 0.01 mV) and increase in S (0.20 ± 0.02 mV) and T (0.08 ± 0.03 mV) amplitude. PQ (-20.3 ± 5.2 ms) and RR (-519 ± 14 ms) interval and P duration (-21.1 ± 3.0 ms) decreased (P < .001). APDs were significantly associated with a singular positive P wave (OR: 11.0, P < .001) and were more likely to have a monophasic positive T wave (OR: 9.2, P < .001). A smaller RR coupling interval was associated with an increased relative difference in S amplitude (P < .01). CONCLUSIONS: Atrial premature depolarizations may lead to changes in QRS and T wave morphology. Knowledge of these changes is important to avoid interpreting certain APDs as VPDs.

Noninvasive determination of atrial fibrillation cycle length by atrial colour tissue Doppler imaging in horses.

REASONS FOR PERFORMING STUDY: Atrial fibrillation cycle length (AFCL) is an indicator of atrial electrical remodelling during atrial fibrillation (AF). OBJECTIVES: To compare AFCL measured invasively from an intra-atrial electrogram (AFCLEGM ) with AFCL measured noninvasively by atrial colour tissue Doppler imaging (AFCLTDI ). STUDY DESIGN: Prospective descriptive clinical study. METHODS: Measurements were performed in 31 episodes of AF or flutter in 29 horses (588 ± 61 kg bwt, 9 ± 3 years old) admitted for transvenous electrical cardioversion. The AFCLEGM was measured from an intracardiac electrogram using a bipolar sensing/pacing electrode inserted into the right atrium. The AFCLTDI was measured from atrial colour tissue velocity curves in the following 5 regions: 1) left atrial free wall from a right parasternal 4-chamber view, 2) left atrial free wall from a short-axis view, 3) left atrial free wall from a left parasternal long-axis view, 4) interatrial septum, and 5) right atrial dorsal wall near the tuberculum intervenosum. The AFCLEGM and AFCLTDI from the 5 regions were compared using a one-way repeated-measures ANOVA with Bonferroni correction for multiple comparisons and calculation of the Bland-Altman mean bias and limits of agreement of AFCLEGM and AFCLTDI . RESULTS: The AFCLEGM was 161 ± 18 ms in 29 AF episodes. Two horses showed atrial flutter and had an AFCLEGM of 244 and 324 ms. The mean bias between AFCLTDI and AFCLEGM ranged from -18 to +9 ms depending on the atrial wall region. The AFCLTDI was significantly shorter in the left atrial free wall from the right parasternal 4-chamber view and short-axis view than in the other regions (P<0.001). CONCLUSIONS: Tissue Doppler imaging allows noninvasive measurement of AFCL in horses with AF and is able to identify spatial differences within the equine atria. Atrial fibrillation cycle length is an indicator of atrial electrical remodelling and is an important parameter to study AF pathophysiology or the effect of antiarrhythmic drugs.

Atrial fibrillation cycle length and atrial size in horses with and without recurrence of atrial fibrillation after electrical cardioversion.

BACKGROUND: Atrial fibrillation (AF) cycle length (CL) and atrial size have been used in humans to characterize electrical and structural remodeling to predict outcome of cardioversion of AF and risk for AF recurrence (rAF). HYPOTHESIS: Atrial fibrillation cycle length can be determined in horses with AF, and AFCL and atrial size are related to risk for rAF. ANIMALS: Eighteen horses with naturally occurring AF that were successfully converted to sinus rhythm (SR) by transvenous electrical cardioversion (TVEC). METHODS: Prospective study. Horses with severe valvular regurgitation, left atrial enlargement, or that required sedation for catheter placement were excluded. In all horses intra-atrial electrograms were recorded and estimated AF duration and echocardiographic parameters were determined before TVEC. The follow-up time was 1 year after TVEC. RESULTS: Atrial fibrillation cycle length could be determined in all horses. The AFCL and the shortest 5th percentile (p5) AFCL in horses with rAF (n = 6 or 33%) were (mean ± SD) 157 ± 28 and 134 ± 24 milliseconds, respectively, and in those maintaining SR (n = 12 or 67%) 166 ± 13 and 141 ± 13 milliseconds, respectively. Significant parameters to predict rAF were (1) the ratios of the p5AFCL to the left atrium (LA) sizes corrected to the size of aorta (AO) and (2) LA sizes corrected to the size of AO. CONCLUSIONS AND CLINICAL IMPORTANCE: Before TVEC, assessment of LA size and atrial electrophysiologic characteristics might help to identify horses at increased risk for AF recurrence.

Two-dimensional speckle tracking for quantification of left ventricular circumferential and radial wall motion in horses.

REASONS FOR PERFORMING STUDY: The use of two-dimensional speckle tracking (2DST) for quantification of left ventricular (LV) function has recently been described in horses using long-axis images and short-axis images at chordal but not at papillary muscle level. OBJECTIVES: To compare the feasibility and reliability of 2DST for quantification of circumferential and radial LV function in short-axis images at papillary muscle and chordal level. METHODS: Repeated echocardiographic examinations were performed on 10 healthy trotter horses by 2 observers from a right parasternal short-axis view at papillary muscle and chordal level. Segmental and averaged peak values and timing of circumferential and radial strain and strain rate, radial displacement and rotation were measured in 6 LV wall segments in each imaging plane. Global peak values were calculated for circumferential strain and strain rate. The inter- and intraobserver within- and between-day variability was assessed by calculating coefficients of variation for repeated measurements. RESULTS: 2DST analysis was feasible in each cardiac cycle, although tracking was often inadequate during early diastole. Measurements of averaged systolic circumferential and radial strain and strain rate and radial displacement as well as global circumferential strain and strain rate could be determined with low variability. Early and late diastolic strain rate and systolic rotation showed a moderate variability. Radial segmental measurements were more reliable than circumferential measurements. The interventricular septum showed a higher circumferential and lower radial strain compared with the LV free wall. Peak timing was earlier at papillary muscle compared with chordal level. CONCLUSIONS: 2DST measurements of global and regional circumferential and radial LV wall motion are feasible both at papillary muscle and chordal level. POTENTIAL RELEVANCE: Several measurements had good reliability and should be used for evaluation of the technique in a clinical setting.

Ventricular response during lungeing exercise in horses with lone atrial fibrillation.

REASONS FOR PERFORMING THE STUDY: Atrial fibrillation (AF) is the most important dysrhythmia affecting performance in horses and has been associated with incoordination, collapse and sudden death. Limited information is available on ventricular response during exercise in horses with lone AF. OBJECTIVES: To investigate ventricular response in horses with lone AF during a standardised lungeing exercise test. METHODS: A modified base-apex electrocardiogram was recorded at rest and during a standardised lungeing exercise test from 43 horses diagnosed with lone AF. During the test horses walked for 7 min, trotted for 10 min, cantered for 4 min, galloped for 1 min and recovered for 7 min. RESULTS: Individual average heart rate during walk ranged from 42 to 175 beats/min, during trot from 89 to 207 beats/min, during canter from 141 to 269 beats/min, and during gallop from 191 to 311 beats/min. Individual beat-to-beat maximal heart rate ranged from 248 to 492 beats/min. Ventricular premature depolarisations were present in 81% of the horses: at rest (16%), during exercise (69%), and during recovery (2%). In 33% of the horses, broad QRS complexes with R-on-T morphology were found. CONCLUSIONS: Exercising horses with lone AF frequently develop disproportionate tachycardia. In addition, QRS broadening and even R-on-T morphology is frequently found. QRS broadening may originate from ventricular ectopic foci or from aberrant intraventricular conduction, for example due to bundle branch block. This might explain the high number of complexes currently classified as ventricular premature depolarisations. POTENTIAL RELEVANCE: Prevalence of QRS broadening and especially R-on-T was very high in horses with AF and was found at low levels of exercise. These dysrhythmias are considered risk factors for the development of ventricular tachycardia and fibrillation and they might explain signs of weakness, collapse or sudden death that have been reported in horses with AF.

Cardiac changes in horses with atypical myopathy.

BACKGROUND: Atypical myopathy (AM) is an acute, fatal rhabdomyolysis in grazing horses that mainly affects skeletal muscles. Postmortem examinations have shown that myocardial damage also occurs. Limited information is available on the effect of AM on cardiac function in affected and surviving horses. OBJECTIVES: To describe electrocardiographic and echocardiographic changes associated with AM in the acute stage of the disease and after follow-up. ANIMALS: Horses (n = 12) diagnosed with AM in which cardiac ultrasound examination and ECG recording were available. METHODS: All horses underwent clinical examinations, serum biochemistry, electrocardiography, and echocardiography. Four surviving horses underwent the same examinations after 2-10 weeks. RESULTS: All but 1 horse had increased cardiac troponin I concentrations and 10 horses had ventricular premature depolarizations (VPDs). All horses had prolonged corrected QT (QT(cf) ) intervals on the day of admission and abnormal myocardial wall motion on echocardiography. One of the surviving horses still had VPDs and prolonged QT(cf) at follow-up after 10 weeks. CONCLUSIONS AND CLINICAL IMPORTANCE: The AM results in characteristic electrocardiographic and echocardiographic changes and may be associated with increased cardiac troponin I concentrations and VPDs. In survivors, abnormal cardiac function still may be found at follow-up after 10 weeks. Additional research in a larger group of horses is necessary to identify the long-term effects of AM on cardiac function.

Oesophageal electrocardiography in healthy horses.

REASONS FOR PERFORMING STUDY: In human medicine, oesophageal electrocardiography (ECG) is a well-established technique that magnifies P waves with respect to the QRS complex. OBJECTIVES: To investigate the feasibility of oesophageal ECG recording in horses and its ability to produce larger P waves compared with base-apex and unipolar recordings. METHODS: Bipolar and unipolar ECG were performed using oesophageal and surface electrodes. Oesophageal ECG was obtained from 6 different recording configurations at different oesophageal depths. Amplitudes of P, Q, R, S and T waves were measured from 3 different cardiac cycles for each recording configuration and depth. RESULTS: Oesophageal ECG was feasible in all horses. For all oesophageal recording configurations, significantly larger P waves were recorded from a depth that equalled 'height of the withers + 10 cm' (HW(+10) ) than from any other depth. P/QRS(magn), the ratio between the P wave and QRS complex magnitudes, was largest for intraoesophageal recordings with an interelectrode distance of 10 cm, at HW(+10), where it was significantly larger than base-apex and unipolar recordings. Base-apex recording resulted in significantly smaller P waves than all other recording configurations and significantly smaller P/QRS(magn) ratios than all other recording configurations except one combined oesophageal-surface recording (E/S(low)). CONCLUSIONS: Oesophageal ECG recording is feasible in horses and effective in magnifying P wave amplitude. POTENTIAL RELEVANCE: The procedure is promising for diagnosis of supraventricular tachydysrhythmias and might be used in electrophysiological studies and for cardiac pacing.

Tissue Doppler imaging and 2-dimensional speckle tracking of left ventricular function in horses exposed to lasalocid.

BACKGROUND: Tissue Doppler imaging (TDI) and 2-dimensional speckle tracking (2DST) can quantify left ventricular (LV) function in horses. OBJECTIVES: To evaluate LV function by TDI and 2DST in horses with myocardial dysfunction after accidental ionophore intoxication. ANIMALS: Sixty-seven horses exposed to lasalocid in feed. METHODS: Prospective study. Horses were included in the study if a full cardiac examination was performed, consisting of determination of cardiac troponin I (cTnI), electrocardiography, and echocardiography. By TDI, radial systolic velocity and strain were measured. By 2DST, circumferential (SC) and radial (SR) strain at papillary muscle and chordal level and longitudinal (SL) strain were measured. RESULTS: Twenty horses showed signs of myocardial injury. Forty-nine examinations were performed on these horses between day 30 and 490 after suspected onset of exposure. Five horses had increased cTnI and ventricular tachycardia and 15 had increased cTnI without ventricular tachycardia. Horses with mild myocardial damage showed few significant differences compared with a control group. Horses with severe myocardial damage showed severely decreased TDI, 2DST and fractional shortening measurements (P < .05), indicating impaired LV function. Long-term follow-up of 2 surviving horses demonstrated full recovery in 1 horse and permanent myocardial fibrosis in the other. The lowest measurements per horse (n = 20) for all TDI measurements, SL, SR at chordal level, and FS correlated significantly with maximal cTnI (P < .05). Over all examinations (n = 49), TDI and 2DST measurements correlated well with FS (P < .05). CONCLUSIONS AND CLINICAL IMPORTANCE: The TDI and 2DST measurements allowed accurate detection and quantification of LV dysfunction in horses exposed to lasalocid.

Acute and long-term cardiomyopathy and delayed neurotoxicity after accidental lasalocid poisoning in horses.

BACKGROUND: Horses are extremely susceptible to ionophore intoxication. Although numerous reports are available regarding monensin, little is known about lasalocid toxicity. OBJECTIVES: To describe accidental lasalocid poisoning on a farm in Belgium. ANIMALS: Eighty-one horses, of which 14 demonstrated clinical signs from day 0-21 after being fed a new concentrate batch. One horse died on day 20 and another on day 27. METHODS: The most severe cases (n = 7), admitted to the clinic on day 29-46, underwent cardiac examination and blood biochemical analysis, including determination of plasma cardiac troponin I (cTnI) at admission and during follow-up. On day 57-70, cardiac examination, cTnI determination or both were undertaken on 72 remaining horses. RESULTS: Short-term effects of lasalocid intoxication included inappetance, lethargy, sweating, and muscular weakness. All 7 horses admitted to the clinic demonstrated signs of myocardial degeneration such as increased cTnI, dysrhythmia and reduced myocardial contractility. Four horses developed ataxia on day 40-50. Five horses died or were euthanized on day 30-370, 2 horses recovered fully and returned to previous athletic use. None of the 72 remaining horses exhibited clinical signs between day 57-70, but 34 had dysrhythmia and 13 had increased cTnI concentrations. After a period of rest, all horses returned to their previous work. Lasalocid was detected in hepatic tissue of 2 necropsied horses. CONCLUSIONS AND CLINICAL IMPORTANCE: Lasalocid intoxication induced myocardial and neurological damage. Although uncommon, this should be included as differential diagnosis for unexplained inappetance, signs of depression, cardiomyopathy, and ataxia in horses.

Quantification of left ventricular longitudinal strain, strain rate, velocity, and displacement in healthy horses by 2-dimensional speckle tracking.

BACKGROUND: The quantification of equine left ventricular (LV) function is generally limited to short-axis M-mode measurements. However, LV deformation is 3-dimensional (3D) and consists of longitudinal shortening, circumferential shortening, and radial thickening. In human medicine, longitudinal motion is the best marker of subtle myocardial dysfunction. OBJECTIVES: To evaluate the feasibility and reliability of 2-dimensional speckle tracking (2DST) for quantifying equine LV longitudinal function. ANIMALS: Ten healthy untrained trotter horses; 9.6 ± 4.4 years; 509 ± 58 kg. METHODS: Prospective study. Repeated echocardiographic examinations were performed by 2 observers from a modified 4-chamber view. Global, segmental, and averaged peak values and timing of longitudinal strain (SL), strain rate (SrL), velocity (VL), and displacement (DL) were measured in 4 LV wall segments. The inter- and intraobserver within- and between-day variability was assessed by calculating the coefficients of variation for repeated measurements. RESULTS: 2DST analysis was feasible in each exam. The variability of peak systolic values and peak timing was low to moderate, whereas peak diastolic values showed a higher variability. Significant segmental differences were demonstrated. DL and VL presented a prominent base-to-midwall gradient. SL and SrL values were similar in all segments except the basal septal segment, which showed a significantly lower peak SL occurring about 60 ms later compared with the other segments. CONCLUSIONS AND CLINICAL IMPORTANCE: 2DST is a reliable technique for measuring systolic LV longitudinal motion in healthy horses. This study provides preliminary reference values, which can be used when evaluating the technique in a clinical setting.

trans-Monounsaturated Acids in a Marine Bacterial Isolate.

A sedimentary bacterial isolate has been shown to contain trans-monounsaturated fatty acids (6% of the total fatty acids). The ratio of trans- to cis-acids in this isolate was in the range 3.2 to 7.6. The identification of trans-monounsaturated acids in a marine bacterium implied that the trans-acids which have been reported in recent sediments could derive, in whole or part, from direct bacterial input.