Effect of electrode cooling with high irrigation rate on pulsed field ablation lesion characteristics.

The deficiency of irrigation water is a main factor of limiting the growth and production of fruit trees, particularly in arid and semi-arid areas regions. So this study was conducted in order to assess the influence of applying silicon in the nano form to minimize the negative effects caused by water stress. A field trial was behaved in 2016 and 2017 seasons at Beheira Governorate to study the effect of three rates of drip irrigation viz.high irrigation rate (control=100%) and two deficit irrigation regimes (75 and 50% from the control), foliar application of nano- silicon (0, 100, 200 and 300ppm) and their interaction on growth, yield and water relations of ''Washington Navel'' orange trees grown in sandy soil and irrigated by drip irrigation method. The findings showed that, deficit irrigation treatment (I3) was related with reduced vegetative growth aspects (canopy volume, No. of shoots /branch, Shoot length) as well as stomatal resistance, however transpiration rate was increased in both seasons, in addition, nano-silicon spraying at 300 or 200ppm caused a significant increase in previous growth aspects over the control.The combination between high or moderate irrigation rate (I1 or I2) with nano-silicon spray at 300 ppm (S4) were more effective in enhancing growth parameters. In both seasons, deficit irrigation treatment (I1) decreased leaf mineral contents and increased leaf proline content. However, high concentration of nano-silicon markedly increased leaf mineral contents but reduced leaf proline contents. Both low and high irrigation rates (I2 and I3) or high concentration of nano-silicon (S4) and their interaction achieved the highest values of bound water and osmotic pressure and the lowest values of total and free water contents. Furthermore, the yield and components, water use efficiency and most of external and internal fruit properties were significantly increased under moderate irrigation (I2) or high concentration of nano-silicon and their interaction (I2 xS4), while, the percentage of fruit splitting was decreased. Finally, trees irrigated with moderate irrigation rate combined with nano-silicon at (300 ppm) enhancement the growth, yield and fruit properties. On the contrary decreased fruit splitting(%) and applied irrigation water by 25% , whereas, increased water use efficiency compared to high irrigation rate (control) without nano-silicon spray.

The availability and proper irrigation scheduling of water are some of the most significant limitations on citrus production in Florida. The proper volume of citrus water demand is vital in evaluating sustainable irrigation approaches. The current study aims to determine the amount of irrigation required to grow citrus trees at higher planting densities without detrimental impacts on trees’ water relation parameters. The study was conducted between November 2017 and September 2020 on young sweet orange (Citrus sinensis) trees budded on the ‘US-897’ (Cleopatra mandarin x Flying Dragon trifoliate orange) citrus rootstock transplanted in sandy soil at the Southwest Florida Research and Education Center (SWFREC) demonstration grove, near Immokalee, Florida. The experiment contained six planting densities, including 447, 598, and 745 trees per ha replicated four times, and 512, 717, and 897 trees per ha replicated six times. Each density treatment was irrigated at 62% or 100% during the first 15 months between 2017 and 2019 or one of the four irrigation rates (26.5, 40.5, 53, or 81%) based on the calculated crop water supplied (ETc) during the last 17 months of 2019–2020. Tree water relations, including soil moisture, stem water potential, and water supplied, were collected periodically. In addition, soil salinity was determined. During the first year (2018), a higher irrigation rate (100% ETc) represented higher soil water contents; however, the soil water content for the lower irrigation rate (62% ETc) did not represent biological stress. One emitter per tree regardless of planting density supported stem water potential (Ψstem) values between −0.80 and −0.79 MPa for lower and full irrigation rates, respectively. However, when treatments were adjusted from April 2019 through September 2020, the results substantially changed. The higher irrigation rate (81% ETc) represented higher soil water contents during the remainder of the study, the lower irrigation rate (26.5% ETc) represents biological stress as a result of stem water potential (Ψstem) values between −1.05 and −0.91 MPa for lower and higher irrigation rates, respectively. Besides this, increasing the irrigation rate from 26.5% to 81%ETc decreased the soil salinity by 33%. Although increasing the planting density from 717 to 897 trees per hectare reduced the water supplied on average by 37% when one irrigation emitter was used to irrigate two trees instead of one, applying an 81% ETc irrigation rate in citrus is more efficient and could be managed in commercial groves.

Conversion of wastewater to reclaimed water for crop irrigation conserves water and is an effective way to handle a growing urban problem: the disposal of wastewater. Water Conserv II is a large reclaimed water project developed by Orlando and Orange County, Fla., that presently irrigates ≈1900 ha of citrus. The project includes a research component to evaluate the response of citrus to irrigation using reclaimed water. Citrus trees in an experimental planting responded well to very high application rates of reclaimed water. Irrigation treatments included annual applications of 400 mm of well water, and 400, 1250, and 2500 mm of reclaimed water. The 2500-mm rate is excessive, and since disposal was of interest, this rate was used to determine if citrus could tolerate such high rates of irrigation. The effects of these treatments were compared on `Hamlin' orange [Citrus sinensis (L.) Osb.] and `Orlando' tangelo (C. paradisi Macf. × C. reticulata Blanco) combined with four rootstocks: Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.], Cleopatra mandarin (C. reticulata Blanco), sour orange (C. aurantium L.), and Swingle citrumelo (C. paradisi × P. trifoliata). Growth and fruit production were greatest at the highest irrigation rate. Concentration of soluble solids in the juice was usually lowered by the highest irrigation rate, but total soluble solids per hectare were 15.5% higher compared to the 400-mm rate, due to the greater fruit production. While fruit soluble solids were usually lowered by higher irrigation, the reduction in fruit soluble solids observed on three of the rootstocks did not occur in trees on Carrizo citrange. Fruit peel color score was lower but juice color score was higher at the highest irrigation rate. Crop efficiency (fruit production per unit of canopy volume) was usually lower at the 2500-mm rate and declined as trees grew older. Weed cover increased with increasing irrigation rate, but was controllable. Irrigation with high rates of reclaimed water provided a satisfactory disposal method for treated effluent, benefited growth and production of citrus, and eliminated the need for other sources of irrigation water. Reclaimed water, once believed to be a disposal problem in Florida, is now considered to be one way to meet irrigation demands.

This study was designed to determine the effects of different irrigation rates with reclaimed water on citrus tree growth and yield. High application rates (1270 and 2540 mm per year) of highly treated reclaimed water were compared to a recommended rate of 406 mm per year of reclaimed or well water. Greater irrigation significantly increased tree growth and fruit yield. Canopy volume at the 2540 mm rate was 55% greater than the 406 mm rate. With Hamlin orange and Orlando tangelo, fruit yields at the highest rate were 39 and 71% greater, respectively, than the lowest rate. Soluble solids were diluted at the higher irrigation rates, but total production of soluble solids per hectare was significantly greater at the high irrigation rates. Yield response was greatest at the high irrigation rate with Swingle citrumelo rootstock. On deep sands, high irrigation rates can improve tree growth and yield in a humid region.

Funding AcknowledgementsType of funding sources: Private company. Main funding source(s): Boris Schmidt, KR Julian Chun and Stefano Bordignon received speaking honoraria from Medtronic and Boston ScientificBackgroundThe cryoballoon (CB) is one of the most commonly used single shot devices for pulmonary vein isolation in patients with atrial fibrillation (AF). Pulsed field ablation (PFA) is a new non-thermal, tissue selective approach for pulmonary vein isolation.PurposeWe sought to compare procedural safety and efficacy of these single shot ablation techniques.MethodsConsecutive AF patients (paroxysmal / persistent AF) who underwent CB based pulmonary vein isolation (PVI) between November 2020 and February 2022 were enrolled and compared with patients who underwent PFA ablation in the same time period. Patients that underwent ablation beyond PVI (except for cavo-tricuspid isthmus ablation) were excluded. CB PVI was performed using the second-generation CB (CB 28 mm) with 240 sec based freeze protocol and bonus freeze delivery in case of time-to-isolation (TTI) >75 sec. PFA was performed using the Farawave catheter, using the 31 or 35 mm device. All procedures were performed under deep sedation.ResultsData from 400 consecutive patients were collected. Most baseline characteristics like age (CB: 67,5 ± 15,3; PFA: 68,4 ± 11; p=0,49), BMI (CB: 28,6 ± 6,3; PFA: 27,9 ± 5,6; p=0,27) and gender (male) (CB: 54%; PFA: 59%; p=0,31) were comparable between the two groups. All PVIs were successfully completed.In 98% (196) of patients in the CB group and 100% (200) in the PFA group, PVI was performed using solely CB or PFA respectively, meaning additional touch up ablation was only needed in 4 CB patients (2%; p=0,044) and 4 veins.Procedure time was significantly shorter in the PFA group (CB: 53 ± 15,3 minutes; PFA: 36,8 ± 13,5 minutes; p<0,001), whereas no difference in fluoroscopy time (CB: 8,1 ± 4,4 minutes; PFA: 7,8 ± 3,3 minutes; p=0,2) was observed. The rate of concomitant CTI-ablation was equal in both groups (CB: 1,5%; PFA: 1,5%; p=1,0). Complication rate was 3,5% with PFA and 6,5% in CB (p=0,17), a difference mostly driven by persistent phrenic nerve palsies (CB: 1,5%; PFA: 0%; p=0,08).All patients are out of the blanking period. There were 80 recurrences in blanking time (CB: 41; PFA: 39; p=0,8). In CB 19,5% of blanking time recurrences were atrial tachycardias compared to 35,9% in PFA (p=0,1). The average time to blanking recurrence was 14,1 ± 21,5 days in CB and 20,5 ± 23,2 in PFA (p=0,2). In total, there were 7 repeat procedures (4 in CB and 3 in PFA; p=0,7) during blanking time due to arrhythmias, despite of antiarrhythmic drugs and/or cardioversion.At the time of this analysis, the first hundred patients in each group reached one-year follow-up. Recurrence free survival after one year for patients with PAF was 82,6% in CB and 80,0% in PFA. In patients with persistent AF it was 70,8% in CB and 67,8% in PFA.ConclusionCryoballoon and pulsed field ablation are both highly effective and safe techniques for PVI. PFA had a shorter procedure time, whereas the one year follow up was similar for both techniques.Procedural dataProcedural complications

Background: Pulsed field ablation (PFA) has emerged as an innovative technology for treating cardiac arrhythmias. PFA increases cell permeability, which can lead to apoptosis. Greater PFA energy may be necessary to ablate ventricular myocardium for ventricular tachycardia circuits, but this carries risks of side effects such as gaseous formation (microbubbles) and hemolysis. Ethanol (EtOH) infusion has been used to ablate pathologic myocardial tissues in hypertrophic cardiomyopathy and for refractory arrhythmias. Hypothesis: We hypothesize that PFA in the ventricle can increase EtOH uptake through PFA-generated pores, thereby enhancing ablation efficacy, even at low powers, by utilizing the cell permeability effects of PFA. Aim: The aim of this study is to investigate the effect of local EtOH infusion after PFA on lesion size in porcine ventricles. Methods: The ventricles of five porcine subjects were ablated in vivo with a PFA low power setting (750 V, at 20 μs for 50 pulses separated by 200 ms) using a focal bipolar irrigated ablation catheter and BTX 830 electroporation generator (Harvard Apparatus). After PFA was performed, 2 ml of 90 % EtOH vs. saline (control) was infused through the catheter tip to the site of ablation. We compared the electrograms voltage amplitude reduction before and after PFA, and the ablation lesion characteristics. Results: A total of 10 lesions in the control group and 9 lesions in the EtOH group were analyzed. For the controls, the voltage after PFA was not reduced. In contrast, for the EtOH group, the voltage after PFA was significantly reduced (Figure 1A). On gross pathology, there were significant differences in ablation lesion depths and volumes between the 2 lesion sets (Figure 1A-B). Conclusion: Local EtOH infusion after ventricular PFA enhanced acute efficacy of electroporation. Concurrent PFA with local EtOH infusion has the potential to improve efficacy without requiring higher energy parameters, thereby reducing PFA risks. Future studies on chronic efficacy are warranted.

`Hamlin' oranges and `Orlando' tangelos on four rootstocks have been irrigated since planting in 1987 with highly treated reclaimed effluent water at application rates of ≈500, 1250, and 2500 mm/year. Reclaimed water treatments have been compared to a well water control at 500 mm/year. Tree growth, yield, and fruit quality have been satisfactory for all irrigation treatments. Growth and yield of `Orlando' tangelos was greatest at the 2500 mm rate and yield was highest on `Swingle' citrumelo and `Carrizo' citrange rootstocks. `Orlando' tangelos benefited more from the high irrigation rates than `Hamlin' oranges. Dilution of soluble solids in the juice by high irrigation rates has diminished as trees matured. Leaf nutrient content was influenced by irrigation, variety, and rootstock. Reclaimed water supplied all the phosphorous and boron needed for citrus production. Soil pH increased due to irrigation with reclaimed water. No disease problems have resulted from the high irrigation rates. Irrigation with high rates of reclaimed water on deep well-drained sands is not detrimental and has benefited citrus production.

`Hamlin' oranges and `Orlando' tangelos on four rootstocks have been irrigated since planting in 1987 with highly treated reclaimed effluent water at application rates of ≈500, 1250, and 2500 mm/year. Reclaimed water treatments have been compared to a well water control at 500 mm/year. Tree growth, yield, and fruit quality have been satisfactory for all irrigation treatments. Growth and yield of `Orlando' tangelos was greatest at the 2500 mm rate and yield was highest on `Swingle' citrumelo and `Carrizo' citrange rootstocks. `Orlando' tangelos benefited more from the high irrigation rates than `Hamlin' oranges. Dilution of soluble solids in the juice by high irrigation rates has diminished as trees matured. Leaf nutrient content was influenced by irrigation, variety, and rootstock. Reclaimed water supplied all the phosphorous and boron needed for citrus production. Soil pH increased due to irrigation with reclaimed water. No disease problems have resulted from the high irrigation rates. Irrigation with high rates of reclaimed water on deep well-drained sands is not detrimental and has benefited citrus production.

Bell pepper (Capsicum annum L.) plants have a high demand for water and nutrients and are sensitive to water stress during the establishment period and fruit setting. High levels of irrigation are often applied in order to maximize yields. However, field observations suggest that excessive irrigations may negatively affect bell pepper plants. The objective was to evaluate the effects of irrigation rate on plant growth and fruit yield. The trial was conducted in Spring 2003 at the Coastal Plain Experiment Station, Tifton, Ga. Drip-irrigated bell pepper (`Stiletto') plants were grown on black plastic mulch in 1-m wide beds (1.8-m centers). Plants were irrigated with an amount of water that ranged from 33% to 167% the rate of evapotranspiration (ET), adjusted by crop stage of development. Soil moisture content (% by volume) over the season was continuously monitored with time domain reflectometry sensors connected to a datalogger. The results showed that the average soil moisture content for the season increased with increasing rates of irrigation. Vegetative top fresh wt. and marketable fruit yield were reduced at both, low (33% ET) and high (166% ET) rates of water application. However, irrigation rate had a stronger effect on fruit yield than on top fresh wt. Plants supplied with high irrigation rates appeared to be more chlorotic compared to plants irrigated at medium rates (100% ET). There was a tendency for higher incidences of soil borne diseases (Pythium sp., Phytophtora capsici) in plants receiving higher rates of irrigation. The conclusion is high irrigation rates (&gt;166% ET) are not recommended since they waste water and may result in both, higher incidences of soil-borne diseases and reduced bell pepper yields.

Citrus trees in an experimental planting responded well to high application rates of reclaimed water. Irrigation treatments included annual applications of 400 mm of well water and 400, 1250, and 2500 mm of reclaimed water. The effects of these irrigation treatments on two citrus cultivars (`Hamlin' orange and `Orlando' tangelo) combined with four rootstocks were compared. Growth and fruit production were better at the higher irrigation rates. The concentration of soluble solids in juice was diluted at the highest irrigation rate, but total soluble solids per hectare increased due to the greater fruit production. Average soluble solids/ha production was &gt;15% higher at the 2500-mm rate than the 400-mm reclaimed water rate. While fruit soluble solids were usually lowered by higher irrigation, the reduction in fruit soluble solids observed on three of the rootstocks did not occur in trees on Carrizo citrange. Trees on Cleopatra mandarin grew similarly at the different irrigation rates, but canopy volume of trees on Swingle citrumelo was significantly smaller at the 400 mm rate than at the 2500 mm rate. Fruit peel color score was lower but juice color score was higher at the highest irrigation rate. Weed pressure increased with increasing irrigation rate, but was controllable. Both juice and fruit soluble solids were higher on Swingle citrumelo and lower on Cleopatra mandarin rootstock. Total soluble solids/ha, solids/acid ratio, and juice color were higher on Swingle rootstock. Reclaimed water, once believed to be a disposal problem in Florida, can be an acceptable source of irrigation water for citrus on well drained soils at rates up to twice the annual rainfall.

Use of roadside infiltration systems using engineered filter soil for optimized treatment has been common practice in Germany for decades, but little documentation is available regarding their long-term treatment performance. Here we present the results of laboratory leaching experiments with intact soil columns (15 cm i.d., 25-30 cm length) collected from two German roadside infiltration swales constructed in 1997. The columns were irrigated with synthetic solutions of unpolluted or polluted (dissolved heavy metals and fine suspended solids) road runoff, as well as a soluble nonreactive tracer (bromide) and a dye (brilliant blue). The experiments were performed at two irrigation rates corresponding to catchment rainfall intensities of approximately 5.1 and 34 mm/h. The bromide curves indicated that preferential flow was more pronounced at high irrigation rates, which was supported by the flow patterns revealed in the dye tracing experiment. Nonetheless, the soils seemed to be capable of retaining most of the dissolved heavy metals from the polluted road runoff at both low and high irrigation rates, except for Cr, which appears to pass through the soil as chromate. Fluorescent microspheres (diameter = 5 μm) used as surrogates for fine suspended solids were efficiently retained by the soils (>99%). However, despite promising treatment abilities, internal mobilization of heavy metals and P from the soil was observed, resulting in potentially critical effluent concentrations of Cu, Zn, and Pb. This is mainly ascribed to high concentrations of in situ mobilized dissolved organic carbon (DOC). Suggestions are provided for possible improvements and further research to minimize DOC mobilization in engineered filter soils.

In this study a growth response of two container-grown ornamentals (Euonymus japonicus ‘Ovatus Aureus’ and Rhododendron ‘Geisha Orange’) grown under different irrigation and fertilization rates was examined. The content of nitrogen (N) and phosphorus (P) in the plant leaves and in leachates was measured. Two levels of irrigation – standard irrigation (SI) and – high irrigation rate (HI), and three control-release fertilizers (CRFs) – Multicote 17-17-17, Osmocote Exact Standard 16-9-12 and Plantacote 15-10-15, applied at the rate of 1.5, 3.0 or 4.5 g·l−1, were applied. Fast-acting fertilizers were used as the control. HI adversely affected the growth and quality of Euonymus but stimulated the growth and increased quality of Rhododendron within two years of cultivation in relation to SI. There were no significant interactions between the irrigation and fertilization treatments; irrespective of water regimes, growth responses of both plant species to used fertilizers were similar. Osmocote and Plantacote at the rate of 3 g·l−1 were the most effective for the growth of Euonymus and Rhododendron plants, except of Euonymus in the second year, when 4.5 g·l−1 CRFs resulted in the best growth of plants. HI increased the amount of runoff water as well as N-NO3 and P-PO4 losses from containers during the entire growing period, irrespective of a fertilizer type. The amount of the nitrate and phosphate in leakage was higher when higher rates of CRFs were applied. Maximum nitrate concentration in leakage was the highest 14 days after the application of CRFs.

Background Women are typically underrepresented in randomized clinical trials, including those focused on atrial fibrillation (AF). The efficacy and safety of pulsed field ablation (PFA) compared to conventional thermal ablation in women have not been well established. Purpose To evaluate the acute efficiency, safety, and long-term outcomes of AF ablation in female-only patients using the Farapulse PFA system versus thermal-based technologies. Methods We conducted a retrospective study on consecutive female patients undergoing AF ablation and enrolled in the ATHENA-CHARISMA registries. Thermal ablation systems (radiofrequency ablation - RF - or cryoablation - Cryo -) were compared to all initial cases approached with the Farapulse PFA system. The ablation approach followed standard clinical practice, with additional lesions performed at the operator’s discretion. Results A total of 1402 female patients (mean age 64±10 years, mean LVEF 59.5±7%, 1058 (75.5%) with paroxysmal AF, 344 (24.5%) with persistent AF) were included: 682 (48.0%) underwent RF ablation, 429 (30.2%) Cryo ablation, and 291 (20.5%) PFA. The PFA group had significantly shorter procedural times (60 [54-80] min) compared to both RF (120 [90-150] min, p&amp;lt;0.001) and Cryo (90 [60-100] min, p&amp;lt;0.001). Fluoroscopy time was lower in the RF group (13.1 [8.4-20] min) compared to both PFA (15 [11-20] min, p=0.0014) and Cryo (15.7 [11-20] min, p=0.0001). Time to PVI was similar between PFA (19 [13-25] min) and RF (18 [11-26] min, p=0.834), but higher in Cryo (22 [16-31] min, p=0.001 vs RF, p&amp;lt;0.001 vs PFA) cases. Overall complication rates were significantly higher with thermal ablation: 1.4% (n=6) with PFA, 4.4% (n=30) with RF (p=0.021 vs PFA), and 5.1% (n=22) with Cryo (p=0.0076 vs PFA). Complete follow-up information was available for 995 (71.0%) patients. During a median follow-up of 406 [349-571] days, 211 (21.1%) patients experienced AF recurrence (median time to recurrence 224 [143-342] days). The Kaplan-Meier estimated freedom from AF was 81.2% with PFA, 80.4% with Cryo, and 77.0% with RF (log-rank p-value: 0.411). Persistent AF patients had a higher AF recurrence rate than paroxysmal AF patients (28.9% vs 18.6%, p=0.0009; HR=1.72, 95% CI: 1.2 to 2.4, p=0.0002). No significant differences were observed among energy sources when separately analyzing paroxysmal and persistent AF patients. Conclusion In female patients undergoing AF ablation, pulsed field ablation resulted in significantly shorter procedural times and a lower rate of complications compared to conventional thermal ablation systems. Follow-up data showed similar rates of AF freedom across all ablation methods.

Catheter ablation (CA) of post-ablation left atrial tachycardias (LATs) can be challenging. So far, pulsed field ablation (PFA) has not been compared to standard point-by-point radiofrequency current (RFC) energy for LAT ablation. To compare efficacy of PFA vs. RFC in patients undergoing CA for LAT. Consecutive patients undergoing LAT-CA were prospectively enrolled (09/2021-02/2023). After electro-anatomical high-density mapping, ablation with either a pentaspline PFA catheter or RFC was performed. Patients were matched 1:1. Ablation was performed at the assumed critical isthmus site with additional ablation, if necessary. Right atrial tachycardia (RAT) was ablated with RFC. Acute and chronic success were assessed. Fifty-six patients (n = 28 each group, age 70 ± 9 years, 75% male) were enrolled.A total of 77 AT (n = 67 LAT, n = 10 RAT; 77% macroreentries) occurred with n = 32 LAT in the PFA group and n = 35 LAT in the RFC group. Of all LAT, 94% (PFA group) vs. 91% (RFC group) successfully terminated to sinus rhythm or another AT during ablation (P = 1.0). Procedure times were shorter (PFA: 121 ± 41 vs. RFC: 190 ± 44 min, P < 0.0001) and fluoroscopy times longer in the PFA group (PFA: 15 ± 9 vs. RFC: 11 ± 6 min, P = 0.04). There were no major complications. After one-year follow-up, estimated arrhythmia free survival was 63% (PFA group) and 87% (RFC group), [hazard ratio 2.91 (95% CI: 1.11-7.65), P = 0.0473]. Pulsed field ablation of post-ablation LAT using a pentaspline catheter is feasible, safe, and faster but less effective compared to standard RFC ablation after one year of follow-up. Future catheter designs and optimization of the electrical field may further improve practicability and efficacy of PFA for LAT.

Irrigation rate and plant density effects on yield and water use efficiency of drip-irrigated corn