Ecological thresholds of toxic plants for sheep production and ecosystem multifunctionality and their trade-off in an alpine meadow.

Toxic plants are a natural component of alpine meadow which co-evolved with Tibetan sheep for thousands of years. One challenge for indigenous herders is to know the ecological thresholds of toxic plants and maintain their vital functions in ways that are compatible with economic income and ecological conservation. To achieve this, field trials with Tibetan sheep grazing in alpine meadow were conducted to examine the ecological thresholds of toxic plants for sheep production and ecosystem functions and their trade-offs. Our results demonstrated that the changing point values of biomass proportion of toxic plants for dry matter intake and liveweight gain of sheep were 17% and 22%, respectively. The changing point value of biomass (richness) proportion of toxic plants for soil carbon accumulation index was 31% (59%), for soil nutrient cycling index was 38% (42%), and for ecosystem multifunctionality index was 28% (50%). The trade-off between liveweight gain of sheep and ecosystem multifunctionality first decreased and then increased along the gradient of biomass proportion of toxic plants (the value of changing point was 37%), and had a significant negative correlation with richness of toxic plants. In addition, structural equation modeling indicated that toxic plants can affect the trade-off between liveweight gain of sheep and ecosystem multifunctionality though increasing acid detergent fiber of plant and decreasing plant species richness, belowground biomass and soil total phosphorus. Consequently, opinions towards toxic plants should shift from the conventional view that they are serious threat to grassland ecosystem health to an inclusive understanding that they are beneficial to livestock and ecosystem functions under certain ecological thresholds.

Multipolar mapping for catheter ablation of premature ventricular complexes originating from papillary muscles in the structurally normal heart: a case series.

BACKGROUND: Previous studies on radiofrequency catheter ablation of premature ventricular complexes (PVCs) arising from the left ventricle (LV) papillary muscles (PM) show a modest procedural success rate with higher recurrence rate. Our study sought to explore the utility of using a multipolar mapping with a steerable linear duodecapolar catheter for ablating the PM PVCs. METHODS: Detailed endocardial multipolar mapping was performed using a steerable linear duodecapolar catheter in 6 consecutive PM PVCs patients with structurally normal heart. The clinical features and procedural data as well as success rate were analysed. RESULTS: LV endocardial electroanatomic mapping was performed in all patients via a retrograde aortic approach using a duodecapolar mapping catheter. All patients displayed a PVC burden with 16.2 ± 5.4%. Duodecapolar catheter mapping demonstrated highly efficiency with an average procedure time (95.8 ± 7.4 min) and fluoroscopy time (14.2 ± 1.5 min). The mean number of ablation applications points was 6.8 ± 1.9 with an average overall ablation duration of 6.1 ± 3.0 min. The values of earliest activation time during mapping using duodecapolar catheter were 37.8 ± 7.2 ms. All patients demonstrated acute successful ablation, and the PVC burden in all patients after an average follow-up of 8.5 ± 2.0 months was only 0.7%. There were no complications during the procedures and after follow-up. CONCLUSIONS: Mapping and ablation of PM PVCs using a duodecapolar catheter facilitated the identification of earliest activation potentials and pace mapping, and demonstrated a high success rate during follow-up.

Variations of electroanatomic substrates and markers of successful ablation in idiopathic left ventricular tachycardia: role of electroanatomic substrates and potential mechanism of tachycardia.

OBJECTIVES: The variation of the substrates of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT) was not understood. The purpose of this study was to investigate the variation of electroanatomic substrate [slow conduction zone (SCZ) and left ventricular conduction system (LVCS)] in ILVT and control individuals and markers of successful ablation. METHODS: Electroanatomical mapping was performed during sinus rhythm in 20 ILVT patients and 26 control individuals with paroxysmal supraventricular tachycardia. LVCS and SCZ were tagged in geometry and the anatomic aspects were investigated. RESULTS: According to the distribution of Purkinje potential, LVCS was distinguished into three types: left bundle branch (LBB) was divided into two discrete fascicles without interconnections; divided into three separate fascicles; and fanlike structure distribution over septum broadly. The length of LBB and its fascicles in patients with ILVT were slightly longer than those of controls (P > 0.05). In the ILVT group, the SCZ was located at the inferoposterior septum in 17, inferior apical septum in one and two SCZs were located at the posterior and mid-septal in the other two patients, which were greater in size and longer in length than those of six controls (P < 0.05). At the crossover junction area with diastolic potential and Purkinje potential, with the size of 1.5 ± 0.4 cm(2), concealed entertainment and ablation were obtained successfully in all patients with ILVT. CONCLUSION: The anatomy of the LVCS and SCZ is highly variable in patients with ILVT, and the crossover junction area with diastolic potential and Purkinje potential might be a marker of ablation.

The electrophysiological characteristics of isolated diastolic potentials in idiopathic ventricular arrhythmias arising from the right ventricular outflow tract.

OBJECTIVE: The significance of isolated diastolic potentials (IDPs) in patients with idiopathic ventricular arrhythmias (IVAs) arising from right ventricular outflow tract (RVOT) is currently unknown. The objective of this study was to clarify the characteristics of IDPs and its role in guiding ablation in RVOT-IVAs. METHODS AND RESULTS: Twenty-five consecutive patients with RVOT-IVAs and ten control subjects were studied. Electro-anatomical mapping was performed in RVOT during sinus rhythm. The electrophysiological characteristics of IDPs and its relation to successful ablation site were evaluated. Successful ablation was achieved during IVAs in 22 patients and during sinus rhythm in the remaining three. IDPs were recorded in all patients in the vicinity of successful ablation sites during sinus rhythm before ablation, with the area of 1.44 /- 0.28 cm2, maximal amplitude of 0.32 +/- 0.06 mV and the distance to pulmonary valve of 1.39 +/- 0.25 cm. IDPs could still be recorded after ablation except one. Moreover, IDPs were characterized by decremental and/or automatic property by studying intervals between ventricular activation and IDPs (V-IDPs) during sinus rhythm. And V-IDPs intervals during sinus rhythm were longerthan those during IVAs (P = 0.012). However, IDPs were only recorded in one patient in the control group and the incidence of IDPs was remarkably lower than that in the RVOT-IVAs group (1/10 vs. 25/25, P < 0.001). CONCLUSIONS: IDPs were present in patients with RVOT-IVAs. IDPs area and/or border region might be the successful ablation site and their precise mechanism remains to be clarified.

Production and properties of biodiesel produced from Amygdalus pedunculata Pall.

The use of inexpensive vegetable oils as feedstock for biodiesel production is an effective way to reduce biodiesel costs. Here we report production and properties of biodiesel produced from Amygdalus pedunculata which is widespread in arid area in China. Biodiesel produced from A. pedunculata conformed EN 14214, ASTM D6751, and GB/T20828 standards, except for those cetane number and oxidative stability. Cold flow and transportation safety properties were excellent (cold filter plugging point -11°C, flash point 169°C). Additives and antioxidants would be required to meet cetane number and oxidative stability specifications. The addition of 500 ppm tert-butylhydroquinone resulted in a higher induction period (6.7 h), bringing oxidative stability into compliance with all three biodiesel standards.

Identification of the slow conduction zone in a macroreentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia using electroanatomic mapping.

BACKGROUND: Although idiopathic left ventricular tachycardia (ILVT) has been shown to possess a slow conduction zone (SCZ), the details of the electrophysiological and anatomic aspects are still not well understood. OBJECTIVE: We hypothesized that the SCZ can be identified using a 3-dimensional electroanatomic (EA) mapping system. METHODS: Ten patients with ILVT were mapped using a 3-dimensional electroanatomic (EA) mapping system. After a 3-dimensional endocardial geometry of the left ventricular was created, the conduction system with left Purkinje potential (PP) and the SCZ with diastolic potential (DP) in LV were mapped during sinus rhythm (SR) and ventricular tachycardia (VT) and were tagged as special landmarks in the geometry. The electrophysiological and anatomic aspects of it were investigated. RESULTS: EA mapping during SR and VT was successfully performed in 7 patients, during VT in 3 patients. The SCZ with DPs located at the inferoposterior septum was found in 7 patients during SR and all patients during VT. The length of the SCZ was 25.2 ± 2.3 mm with conduction velocity 0.08 ± 0.01 m/s. No differences in these parameters were found between patients during SR and VT (P > 0.05). An area with PP was found within the posterior septum. A crossover junction area with DP and PP was found in 7 patients during SR and VT. This area with DP and PP during SR coincided or were in proximity to such area during VT and radiofrequency ablation targeting the site within the area abolished VT in all patients. CONCLUSION: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified and can be used to guide the ablation of ILVT.

Radiofrequency ablation of the ventricular tachycardia with arrhythmogenic right ventricular cardiomyopathy using non-contact mapping.

BACKGROUND: Intracardiac non-contact mapping provides a rapid and accurate isopotential mapping that facilitates catheter ablation of the ventricular tachyarrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC). METHODS: Thirty-two consecutive patients (26 men and 6 women, mean 37.2 +/- 13.8 years) were treated with ablation. Fourteen patients had a history of syncope/pre-syncope. Two patients had an implantable cardiac defibrillator (ICD) previously implanted. RESULTS: There were 67 ventricular tachycardias (VTs) induced in the 32 patients. The average VT rate was 210 +/- 32.2 (130-310) bpm. There were 42 episodes of VT that had a heart rate > or =200 bpm and 24 of the 32 patients (75%) had > or =2 morphologies of VT. Regional ablation was applied by targeting the earliest VT activation sites under the guidance of non-contact mapping. Acute success was achieved in 84.4% (27/32) patients, and significant improvement was seen in 15.6% (5/32) patients as evidenced by a slower rate of VT. None of the patients experienced syncope/pre-syncope or sudden death during the 28.6 +/- 16 (9-72) month follow-up. There were no complications of the procedure. At the end of follow-up, 81.3% of the patients were free of VT without medication while the rest of the patients achieved a modified success. CONCLUSIONS: The rapid ventricular tachyarrhythmias in ARVC patients can be abolished or improved significantly by regional RF catheter ablation under the guidance of non-contact mapping. There was no sudden cardiac arrest or death in those patients without ICD implantation. Delayed efficacy may occur in some patients after ablation.