Transvenous electrical cardioversion of atrial fibrillation in six horses using custom made cardioversion catheters

Pharmacological conversion of atrial fibrillation (AF) to sinus rhythm in horses can be difficult. The objective of this study was to investigate the feasibility of transvenous electrical cardioversion with custom made catheters in eight horses, of which three had failed cardioversion using quinidine sulfate. Two cardioversion catheters and one pacing/sensing electrode were inserted via the right jugular vein and placed using ultrasound guidance into the left pulmonary artery, the right atrium and the right ventricle, respectively. Because immediate recurrence of AF was encountered in the second horse treated, pre-treatment with amiodarone was given to each of the remaining six horses. Induction of general anaesthesia was associated with dislocation of the cardioversion catheter in three horses, requiring a second catheterisation procedure. During general anaesthesia, biphasic R wave synchronised shocks of up to 360 J were delivered between both cardioversion electrodes. In six horses (75%), including two which had failed quinidine sulfate treatment, sinus rhythm was restored with a mean energy level of 295+/-62 J. No side effects were observed. Blood analysis 3 h after cardioversion revealed normal parameters, including cardiac troponin I values. Transvenous electrical cardioversion of atrial fibrillation with custom made cardioversion catheters can be considered as a treatment option for atrial fibrillation in horses, especially when conventional drugs fail.     

Effects of dobutamine on cardiovascular function and respiratory gas exchange after enoximone in isoflurane-anaesthetized ponies

ObjectiveTo evaluate the combined effects of enoximone and dobutamine on the cardiovascular system and respiratory gas exchange in isoflurane-anaesthetized ponies.Study designProspective, randomized, experimental study.AnimalsSix ponies (286 ± 52 kg), aged 5.0 ± 1.6 years.MethodsAfter sedation (romifidine 80 μg kg⁻¹), anaesthesia was induced with midazolam (0.06 mg kg⁻¹) and ketamine (2.2 mg kg⁻¹) and maintained with isoflurane in oxygen. The ponies were ventilated to maintain eucapnia. After 90 minutes (=T0), enoximone alone (0.5 mg kg⁻¹) (E) or enoximone, followed by a constant rate infusion of dobutamine (0.5 μg kg⁻¹ minute⁻¹) (ED) for 120 minutes, was administered. Each pony received both treatments in a crossover trial, with at least 2 weeks between treatments. Heart rate (HR), cardiac output (CO), stroke volume (SV), right atrial (RAP), systolic (SAP), diastolic (DAP) and mean arterial pressure (MAP), blood gases, systemic vascular resistance (SVR), oxygen delivery (D⌽O₂) and several respiratory gas exchange variables were measured before treatment and until T120. Statistical analysis was based on a mixed model with treatment, time and their interaction as fixed categorical effects, pony as random effect, comparing treatments globally (α = 0.05) and at specific timepoints (Bonferroni-adjusted α = 0.00625).ResultsCompared to enoximone alone, ED treatment produced an increase in HR, CO, SV, RAP, SAP, DAP, MAP, packed cell volume (PCV) and D⌽O₂. The difference was significant from T60 to T120 (except at T80) for HR, throughout the observational period for CO, SAP, MAP, PCV and D⌽O₂, from T40 to T120 for DAP, at T10,T60,T80 and T120 for SV and at T10 and T20 for RAP. Overall decreases occurred in SVR and dead space ventilation (V_D/V_T). V_D/V_T was lower at T20 and from T80 to T120. Venous oxygen saturation was increased from T60 onwards.Conclusions and clinical relevanceThe results suggest that enoximone and dobutamine have additive cardiovascular effects and reduce V_D/V_T in isoflurane-anaesthetized ponies.     

The impact of elevated water nitrate concentration on physiology,growth and feed intake of African catfish Clarias gariepinus (Burchell 1822)

The nitrate threshold concentration in rearing water of African catfish (Clarias gariepinus) was assessed. Female African catfish with an initial mean (SD) weight of 154.3 (7.5) g were exposed to 0.4 (Control), 1.5, 4.2, 9.7 and 27.0 mM nitrate for 42 days. Mean (SD) plasma concentrations of nitrate increased from 71 (29) to 6623 (921) μM at the highest ambient nitrate level. Mean (SD) plasma nitrite concentration ranged from 1.2 (0.5) to 7.9 (9.0) μM. Haematocrit, plasma concentrations of non‐esterified fatty acids (NEFA), cortisol, glucose, lactate, osmolality, gill morphology and branchial Na⁺/K⁺‐ATPase activity were not affected. Feed intake and specific growth rate were significantly reduced at the highest nitrate concentration. We advise not to exceed a water nitrate concentration of 10 mM (140 mg L^?1 NO₃‐N) to prevent the risk of reduced growth and feed intake in African catfish aquaculture.     

Detection of the origin of atrial tachycardia by 3D electro‐anatomical mapping and treatment by radiofrequency catheter ablation in horses

BackgroundAtrial tachycardia (AT) can be treated by medical or electrical cardioversion but the recurrence rate is high. Three‐dimensional electro‐anatomical mapping, recently described in horses, might be used to map AT to identify a focal source or reentry mechanism and to guide treatment by radiofrequency ablation.ObjectivesTo describe the feasibility of 3D electro‐anatomical mapping and radiofrequency catheter ablation to characterize and treat sustained AT in horses.AnimalsNine horses with sustained AT.MethodsRecords from horses with sustained AT referred for radiofrequency ablation at Ghent University were reviewed.ResultsThe AT was drug resistant in 4 out of 9 horses. In 8 out of 9 horses, AT originated from a localized macro‐reentrant circuit (n = 5) or a focal source (n = 3) located at the transition between the right atrium and the caudal vena cava. In these 8 horses, local radiofrequency catheter ablation resulted in the termination of AT. At follow‐up, 6 out of 8 horses remained free of recurrence.Conclusions and Clinical ImportanceDifferentiation between focal and macro‐reentrant AT in horses is possible using 3D electro‐anatomical mapping. In this study, the source of right atrial AT in horses was safely treated by radiofrequency catheter ablation.     

Biostimulant effects of rhizobacteria on wheat growth and nutrient uptake depend on nitrogen application and plant development

The capacity of plant growth-promoting rhizobacteria (PGPR) – Bacillus amyloliquefaciens GB03 (BamGB03), B. megaterium SNji (BmeSNji), and Azospirillum brasilense 65B (Abr65B) – to enhance growth and nutrient uptake in wheat was evaluated under different mineral N fertilizer rates, in sterile and non-sterile soils, and at different developmental stages. In gnotobiotic conditions, the three strains significantly increased plant biomass irrespective of the N rates. Under greenhouse conditions using non-sterile soil, growth promotion was generally highest at a moderate N rate, followed by a full N dose, while no significant effect was observed for the inoculants in the absence of N fertilizer. At 50N, plant biomass was most significantly increased in roots (up to +45% with Abr65B) at stem-elongation stage and in the ears (+19–23% according to the strains) at flowering stages. For some nutrients (N, P, Mn, and Cu), the biomass increases in roots and ears were paralleled with reduced nutrient concentrations in the same organs. Nevertheless, growth stimulation resulted in a higher total nutrient uptake and higher nutrient uptake efficiency. Furthermore, Abr65B and BmeSNji counteracted the reduction of root development caused by a high N supply. Therefore, combining PGPR with a proper cultivated system, N rate, and plant stage could enhance their biostimulant effects.     

Potential dermal pesticide exposure affected by greenhouse spray application technique

BACKGROUND: Operator safety is still one of the main problems concerning greenhouse spray applications in South European horticulture. The main objective of this study was to compare potential dermal exposure (PDE) between traditional handheld spray application techniques (i.e. a standard spray gun walking forwards, a spray lance walking forwards and backwards) and novel spray application techniques with spray booms (i.e. a trolley, the Fumimatic and the Fumicar). RESULTS: PDE varied from 19.7 mL h^?1 for the Fumimatic to 460 mL h^?1 for the spray lance walking forwards. Walking backwards reduced PDE by a factor 7. With the trolley, Fumimatic and Fumicar, PDE was respectively 20, 60 and 8 times lower than with the standard spray gun. With the spray lance, PDE was about 2.5 times higher than with the spray gun. Pesticide distribution over the operator's body was non‐uniform and correlated strongly with the application technique. With the traditional techniques, exposure to the legs and feet represents 60–80% of the total exposure. CONCLUSIONS: Novel spray application techniques using spray booms greatly decrease operator exposure because the operator is not walking directly into the spray cloud and the sprayed crop, and because of their higher capacity. Depending on the type of spray application, different parts of the body need to be protected most. Copyright © 2009 Society of Chemical Industry