Clinical outcome of lesion size index-guided high-power radiofrequency catheter ablation for pulmonary vein isolation in patients with atrial fibrillation: 2-year follow-up.

INTRODUCTION: The long-term efficacy of high-power (50 W) ablation guided by lesion size index (LSI-guided HP) for pulmonary vein isolation (PVI) in patients with atrial fibrillation (AF) remains undetermined. Our study sought to assess the clinical efficacy of LSI-guided HP ablation for PVI in patients with AF and explore the potential predictors associated with clinical outcomes. METHODS: We consecutively included 186 patients with AF who underwent LSI-guided HP (50 W) ablation at Fuwai Hospital from June 2019 to October 2021. The target LSI values of 4.5-5.5 and 4.0-4.5 at the anterior and posterior walls, respectively, were used in our study. The baseline clinical characteristics, procedural and ablation data, and clinical outcomes were evaluated. The independent potential predictors associated with AF recurrence were further evaluated. RESULTS: The incidence rate of first-pass PVI was 83.9% (156/186). A total of 11 883 lesions were analyzed, and compared with posterior walls of pulmonary veins, anterior walls had significantly lower mean contact force (8.2 ± 3.0 vs. 8.3 ± 2.3 g, p = .015), longer mean radiofrequency duration (16.9 ± 7.2 vs. 12.9 ± 4.5 s, p < .001) and higher mean LSI (4.8 ± 0.2 vs. 4.4 ± 0.2, p < .001). The overall incidence of periprocedural complications was 3.7%, and steam pops without pericardial effusion occurred in three patients (1.6%). During a mean follow-up of 24.0 ± 8.4 months, the overall AF recurrence-free survival was 87.1% after a single procedure. Patients with paroxysmal AF had a higher incidence of freedom from AF recurrence than those with persistent AF (91.2% vs. 80.8%, log-rank p = .034). Higher LSI (HR 0.50, p < .001) and paroxysmal AF (HR 0.39, p = .029) were significantly associated with decreased AF recurrence. By receiver operating characteristic analysis, the LSI of 4.7 and 4.3 for the anterior and posterior walls of the PVs had the highest predictive value for AF recurrence, respectively. CONCLUSION: LSI-guided HP (50 W) ablation for PVI was an efficient and safe strategy and led to favorable single-procedure 2-year AF recurrence-free survival in patients with AF. Higher LSI and paroxysmal AF were independent predictors of decreased 2-year AF recurrence. The LSI of 4.7 for the anterior wall and 4.3 for the posterior wall of the PVs were the best cutoff values for predicting AF recurrence after LSI-guided HP ablation.

Catheter Ablation of Premature Ventricular Contractions Originating in the Aortic Sinus Cusp or Great Cardiac Vein: Two QRS Morphologies with One Origin.

BACKGROUND: Premature ventricular contractions (PVCs) originating from aortic sinus cusps (ASCs) can exhibit preferential conduction to right ventricular outflow tract (RVOT). OBJECTIVES: This study aimed to examine the electrophysiological characteristics for guiding catheter ablation in patients with two morphological types of PVCs that originate from ASCs or the great cardiac vein (GCV). METHODS: We analyzed electrocardiogram from 10 patients with PVCs of two QRS morphologies. The patients who exhibited dominant left bundle branch block (LBBB) QRS morphology and less right bundle branch block (RBBB) morphology were designated as group 1 (n = 7), and those with dominant RBBB QRS morphology were designated as group 2 (n = 3). During PVCs, electroanatomical mapping was performed in both RVOT and ASC in group 1 and only performed in ASC or GCV in group 2. RESULTS: In group 1, the earliest ventricular activation preceding the onset of the QRS complex (V-QRS) was recorded for 27 ± 6 ms (range 18-36 ms) in RVOT and 25 ± 6 ms (range 18-34 ms) in the ASC, while V-QRS was recorded for 28 ms, 42 ms, 40 ms in the ASC or GCV in group 2. All patients were successfully ablated at one site finally, including left coronary cusp in seven, left-right coronary cusp commissure in two, and GCV in one. None of the patients experienced recurrence or complications during the 18.4 ± 5.1 (range 6-24 months) months of follow-up. CONCLUSIONS: Two QRS morphologies (LBBB and RBBB with inferior axis) in PVCs could be a predictor of PVCs originating from ASC or GCV.

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.

[Radiofrequency catheter ablation of the premature ventricular contractions originating from His bundle region].

OBJECTIVE: To explore the electrocardiogram and 3-dimensional electroanatomic mapping features and radiofrequency catheter ablation efficacy of patients with premature ventricular contractions (PVCs ) originating from His bundle region. METHODS: Between February 2009 and February 2011, 10 consecutive patients ( 4 male, aged from 19 to 59 years) who underwent ablation for frequent PVCs originating close to His bundle region in our department were included. Electroanatomic mapping of RVOT and ASC, ablation was performed with the 7F 4-mm-tip ablation catheter. RESULTS: Among these 10 patients with PVCs originating from His bundle region, 6 originated from the RVOT, 1 from NCC and 3 from RCC. Eight patients showed LBBB morphology,1 patient with PVCs originated from RCC and 1 patient with PVCs originated from NCC showed RBBB morphology. At the successful ablation sites, local ventricular activation v wave was detected 22-52 (32.6 ± 10.2) ms earlier than the QRS wave in the surface electrocardiogram. The distance between target and His bundle was 5.0-8.4(7.0 ± 1.1)mm. Ablation was successful in all 10 patients without complications (PVCs < 500 beats/24 h post ablation). CONCLUSION: PVCs originating near the His bundle have similar electrocardiographic and electrophysiological characteristics for PVSc originated from the RVOT or ASC. Because of the close anatomical relationship between RVOT and ASC, it is necessary to mapping both RVOT and ASC to accurately identify the site of PVCs origin and to guild successful ablation.

[Value of identifying the slow conduction zone of idiopathic left ventricular tachycardia by electroanatomic mapping].

OBJECTIVE: To explore the value of identifying slow conduction zone(SCZ) of idiopathic left ventricular tachycardia(ILVT) by electroanatomic mapping. METHODS: Twelve patients with ILVT were mapped by a 3-dimensional electroanatomic (EA) mapping system. Left posterior fascicular potential (PP) and the SCZ with diastolic potential (DP) in LV during sinus rhythm (SR) and ventricular tachycardia (VT) were mapped after a three-dimensional endocardial geometry of the left ventricular was established. Then we investigated the electrophysiological and anatomic characteristics of SCZ. RESULTS: EA mapping was successfully performed in 9 patients during SR and VT, and in 3 patients during VT. The SCZ with DP was located at the inferoposterior septum, and the length of the SCZ was (25.1 ± 2.2) mm with a conduction velocity of (0.08 ± 0.01) m/s. There was no difference in these parameters between patients during SR and VT (P > 0.05). There was one area with PP located at the posterior septum. The areas with both DP and PP were found in 9 patients during SR and VT. In addition, this area was coincided with such area during VT during SR and radiofrequency ablation targeting the site within the area abolished VT in all patients. CONCLUSIONS: The ILVT substrate within the junction area of the SCZ and the posterior fascicular can be identified by EA mapping and used to guide the ablation of ILVT.

[Preferential conduction to right ventricular outflow track leads to left bundle-branch block morphology in patient with premature ventricular contraction originating from the aortic sinus cusp].

OBJECTIVE: The purpose of this study was to explore the relationship between originate and breakout and radiofrequency catheter ablation strategy in patients undergoing radiofrequency ablation for premature ventricular contractions originating from the aortic sinus cusp (ASC) using 3-dimensional electro anatomic mapping. METHODS: This study included 21 consecutive patients (10 male) underwent ablation for frequent PVCs originating from ASC in our hospital between May 2009 and February 2012. Electro anatomic mapping and ablation of right ventricular outflow track (RVOT) and left ventricular outflow track (LVOT) were performed with the 7F 4-mm-tip ablation catheter from right femoral vein and artery. Activation mapping and pacing mapping were performed in all patients. RESULTS: Ablation was successful in all 21 patients successful ablation target in left coronary sinus cusp (LCC, n = 17), in right coronary sinus cusp (RCC, n = 2) and in noncoronary sinus cusp (NCC, n = 2). Seven patients showed a RBBB morphology (group A) and 14 patients showed a LBBB morphology (group B). In group A, earliest ventricular activation (EVA) was recorded 22 - 34 (27.4 ± 4.6) ms earlier before QRS at the site of catheter ablation in ASC. In group B, EVA was later in RVOT than that in ASC in 5 patients and EVA at the site of catheter ablation in RVOT and ASC was 22 - 28 (25.2 ± 2.7) ms and 26 - 40 (32.8 ± 5.2) ms, respectively (t = -3.6, P = 0.024) while EVA was earlier in the remaining 9 patients and EVA recorded in RVOT and ASC was 22 - 38 (28.7 ± 5.9) ms and 18 - 28 (22.7 ± 3.6) ms, respectively (t = 3.8, P = 0.005). CONCLUSION: Patients with premature ventricular contractions originating from the ASC often show preferential conduction to the RVOT, which may explain the LBBB morphology of ECG in these patients.

[Management of refractory ventricular tachycardia in patients with non-myxomas primary cardiac tumors].

OBJECTIVE: To summarize the clinical characteristics and treatment experience of patients with non-myxomas primary cardiac tumors accompanied with refractory ventricular tachycardia (VT). METHODS: Clinical and imaging data as well as therapy efficacy and outcome were analyzed in 10 patients with non-myxomas primary cardiac tumors accompanied with refractory VT. RESULTS: There were 5 male and 5 female patients in this cohort [mean age (37.6±18.2) years]. Palpitation was presented in all 10 patients, 7 patients experienced syncope, and 2 patients suffered from amaurosis. The diagnosis was made by combined use of transthoracic echocardiograms, MRI, and CT scan. The time from symptom to diagnosis was (33.2±36.7) months. Symptom-related VT was documented by ECG or Holter monitoring. MRI suggested lipoma in 7 patients, lymphoma in 1 patient and fibroma in another patient. Seven tumors were located in the left ventricle, 1 in right atria, 1 at peri-aortic root and 1 near right ventricular outflow tract. Nine out of 10 patients received anti-arrhythmic drug therapy. The ventricular tachyarrhythmia disappeared after surgical tumor resection in 4 patients. All other patients who were treated with antiarrhythmic drugs, radiofrequency ablation or subtotal excision showed only suboptimal efficacy during (39.4±25.1) months follow-up. CONCLUSION: Surgical tumor removal is the best treatment strategy for the treatment of refractory ventricular tachycardia in patients with primary cardiac benign tumors.

Optimal Lesion Size Index for Pulmonary Vein Isolation in High-Power Radiofrequency Catheter Ablation of Atrial Fibrillation.

Background: Although both high-power (HP) ablation and lesion size index (LSI) are novel approaches to make effective lesions during pulmonary vein isolation (PVI) for atrial fibrillation (AF), the optimal LSI in HP ablation for PVI is still unclear. Our study sought to explore the association between LSI and acute conduction gap formation and investigate the optimal LSI in HP ablation for PVI. Methods: A total of 105 consecutive patients with AF who underwent HP ablation guided by LSI (LSI-guided HP) for PVI in our institute between June 2019 and July 2020 were retrospectively enrolled. Each ipsilateral PV circle was subdivided into four segments, and ablation power was set to 50 W with target LSI values at 5.0 and 4.0 for anterior and posterior walls, respectively. We compared the LSI values with and without acute conduction gaps after the initial first-pass PVI. Results: PVI was achieved in all patients, and the incidence of first-pass PVI was 78.1% (82/105). A total of 6,842 lesion sites were analyzed, and the acute conduction gaps were observed in 23 patients (21.9%) with 45 (0.7%) lesion points. The gap formation was significantly associated with lower LSI (3.9 ± 0.4 vs. 4.6 ± 0.4, p < 0.001), lower force-time integral (82.6 ± 24.6 vs. 120.9 ± 40.4 gs, p < 0.001), lower mean contact force (5.7 ± 2.4 vs. 8.5 ± 2.8 g, p < 0.001), shorter ablation duration (10.5 ± 3.6 vs. 15.4 ± 6.4 s, p < 0.001), lower mean temperature (34.4 ± 1.4 vs. 35.6 ± 2.6°C, p < 0.001), and longer interlesion distance (4.4 ± 0.3 vs. 4.3 ± 0.4 mm, p = 0.031). As per the receiver operating characteristic analysis, the LSI had the highest predictive value for gap formation in all PVs segments, with a cutoff of 4.35 for effective ablation (sensitivity 80.0%; specificity 75.4%, areas under the curve: 0.87). The LSI of 4.55 and 3.95 had the highest predictive value for gap formation for the anterior and posterior segments of PVs, respectively. Conclusion: Using LSI-guided HP ablation for PVI, more than 4.35 of LSI for all PVs segments showed the best predictive value to avoid gap formation for achieving effective first-pass PVI. The LSI of 4.55 for the anterior wall and 3.95 for the posterior wall were the best cutoff values for predicting gap formation, respectively.

Psychological Disturbances and Their Association with Sleep Disturbance in Patients Admitted for Arrhythmia Diseases.

Objectives: This study aimed to assess the depression and anxiety status and their association with sleep disturbance among one single center Chinese inpatients with arrhythmia and help cardiologists better identify patients who need psychological care. Methods: A cross-sectional survey was conducted among 495 inpatients with arrhythmia treated in Fuwai Hospital from October to December 2019. The psychological status and sleep quality were assessed using the Zung Self-Rating Anxiety Scale (SAS), the Zung Self-Rating Depression Scale (SDS) and the Pittsburgh Sleep Quality Index (PSQI). Multivariate logistic regression was used to identify the potential risk factors for anxiety and depression. Results: The mean age of the participants was 52.8 ± 14.4 years, and 58.0% were male. Approximately 18.3% were in an anxious state, and 33.5% were in a depressive state. In multivariate logistic regression, age from 50 to 59 (p = 0.03), unemployment (p = 0.026) and sleep disturbance (p < 0.001) were the risk factors for anxiety status. Cardiac implanted electronic devices (CIEDs) (p = 0.004) and sleep disturbance (p < 0.001) were the risk factors for depression status. A total of 150 patients (30.3%) were categorized as having poor sleep quality (PSQI > 7). The adjusted odds ratio (OR) of having poor sleep quality was 4.30-fold higher in patients with both anxiety and depression (OR: 4.30; 95% confidence interval [CI]: 2.52-7.35); 2.67-fold higher in patients with depression (OR: 2.67; 95% CI: 1.78-4.00); and 3.94-fold higher in patients with anxiety (OR: 3.94; 95% CI: 2.41-6.44). Conclusions: Psychological intervention is critical for Chinese inpatients with arrhythmia, especially for patients aged 50-59, unemployed, or those using CIEDs. Poor sleep quality could be an important risk factor linked to psychological disturbances.

[Association between abnormal electrocardiographic features and disease severity in patients with arrhythmogenic right ventricular cardiomyopathy].

OBJECTIVE: To analyze the relationship between electrocardiographic (ECG) features and disease severity in patients with the arrhythmogenic right ventricular cardiomyopathy (ARVC). METHOD: The study group consisted of 61 subjects with a definite diagnosis of ARVC on the basis of published guideline criteria and patients were divided into 3 subgroups according to the extent of diseased myocardium defined by cardiac magnetic resonance imaging (MRI): Group A: local involvement (n = 19, 31%), Group B: diffuse involvement of whole right ventricle (n = 28, 46%) and Group C: involvement of both right and left ventricles (n = 14, 23%). RESULTS: Normal electrocardiogram was shown in 1 patient in each group. Epsilon wave was detected in 24 (39%) patients, QRS duration was prolonged [≥ 110 ms (V(1)-V(3))] in 21 (34%) patients, S-wave upstroke was prolonged (≥ 55 ms) in 17 (28%) patients, complete right branch bundle block was evidenced in 10 (16%) patients and pathologic Q waves was found in 9 (15%) patients. The incidence of above abnormal ECG changes was increased in proportion to the degree of disease severity (group A < group B < group C). Incidence of Epsilon wave and prolonged QRS duration [ ≥ 110 ms (V(1)-V(3))] were significantly higher in Group C than in Group A. Incidence of prolonged S-wave upstroke (≥ 55 ms) was significantly higher in Group C than in Group A and Group B. T-wave inversion in V(1) leads was often found in Group A. T-wave inversion in inferior leads (V(1)-V(3) leads or beyond V(3)) was often presented in Group B and Group C. CONCLUSIONS: Normal ECG does not exclude the possibility of diagnosis of ARVC. The extent of T-wave inversion in the precordial leads and incidence of Epsilon wave, prolonged QRS duration [ ≥ 110 ms (V(1)-V(3))] and prolonged S-wave upstroke (≥ 55 ms) were related to degree of disease severity in patients with ARVC.

[Association between electrocardiogram characteristics and long-term outcome in patients with idiopathic ventricular fibrillation].

OBJECTIVE: To explore the association between clinical and ECG characteristics and prognoses in patients with idiopathic ventricular fibrillation (VF). METHODS: We reviewed the data from 21 VF patients [male 47.6%, mean age (38.5 ± 19.0) years] with first event of VF, all patients were resuscitated after cardiac arrest and diagnosed as idiopathic VF. The prevalence of J wave was assessed and patients were divided into J wave positive (J+ group) and negative group (J- group). The end point was death or syncope from arrhythmia, and recorded VF recurrence during the follow-up. RESULTS: J wave was frequent in subjects with idiopathic VF (71.4%). Among patients in the J+ group (15 cases), notch on the QRS wave was found in 7 subjects (46.7%), these patients were more likely to suffer from the sudden cardiac arrest during sleep at early morning than those with J wave but without notch on the QRS wave. Two patients dead suddenly in the J+ group and 1 dead from embolism in the J- group during follow-up [mean (42.4 ± 39.9) months]. The mean year-onset of VF or syncope was significantly higher in the J+ group than in the J-group [(1.3 ± 0.5) episodes/year vs. (0.4 ± 0.3) episodes/year, P < 0.01]. J wave positive was also associated with an increased risk of VF recurrence (RR 1.9, 95%CI 1.1 to 2.9, P = 0.03). CONCLUSION: J wave prevalence is high in patients with history of idiopathic VF, and positive J wave is associated with high risk of recurrence of sudden cardiac death.

Inflammation in lone atrial fibrillation.

OBJECTIVES: This study was designed to evaluate the correlation between lone atrial fibrillation and inflammation. METHODS: A total of 411 subjects were enrolled in this study, including 333 patients with lone atrial fibrillation, and 78 controls. C-reactive protein (CRP) and echocardiography were evaluated, and the electrocardiograph was monitored to identify cardiac rhythm at the time of blood sampling. According to the rhythm, paroxysmal atrial fibrillation was divided into presence and absence of atrial fibrillation. RESULTS: Subjects with lone atrial fibrillation had higher CRP levels than controls (media, 1.00 mg/L; IQR, 1.00-2.54 versus media, 1.00 mg/L; IQR, 1.00-1.55; p = 0.016) and subjects with persistent atrial fibrillation had higher CRP levels than those with paroxysmal atrial fibrillation (media, 1.62 mg/L; IQR, 1.00-3.98 versus media, 1.00 mg/L, IQR, 1.00-2.10; p = 0.022), and so did presence of atrial fibrillation rather than absence of atrial fibrillation (media, 2.11 mg/L; IQR, 1.00-3.60 versus media, 1.00 mg/L; IQR, 1.00-1.76; p = 0.000) in paroxysmal atrial fibrillation. However, there was no significant difference in CRP levels between persistent atrial fibrillation and presence of atrial fibrillation in paroxysmal atrial fibrillation (p = 0.992). Neither was there any difference between absence of atrial fibrillation in paroxysmal atrial fibrillation and controls (p = 0.483). In patients with lone atrial fibrillation, atrial fibrillation rhythm (B = 4.85, 95%CI: 2.61-8.99) was the only independent predictor of elevated CRP levels after adjusted covariants. CONCLUSIONS: Patients with lone atrial fibrillation had elevated CRP levels only when they were in atrial fibrillation rhythm and an elevated CRP level was not related to duration of time or history of atrial fibrillation.

Electrocardiographic alterations after chronic right ventricular apical pacing in patients with sinus node dysfunction.

OBJECTIVE: The purpose of this study is to investigate the potential to induce electrical remodeling by chronic right ventricular apical (RVA) in patients with sinus node dysfunction. METHODS: Ninety-two patients with sinus node dysfunction who underwent initial pacemaker implantation were included in the study. During routine clinic visits, electrocardiograms and echocardiograms were recorded. Forty-five patients were also studied as controls. RESULTS: During a mean follow-up time of 3.3 +/- 0.5 years, the intrinsic QRS duration increased from 87 +/- 9 milliseconds before device implantation to 94 +/- 10 milliseconds (P < .001). The left ventricular end-diastolic diameter increased from 46 +/- 3 to 50 +/- 4 mm (P < .001), and the left ventricular ejection fraction decreased from 63% +/- 4% to 57% +/- 5% (P < .001). Logistic regression analysis revealed that elderly age at the time of pacemaker implantation (odds ratio [OR], 3.41; 95% confidence interval [CI], 1.07-10.90; P = .04), RVA pacing (OR, 3.91; 95% CI, 1.10-13.89; P = .03), and coronary artery disease (OR, 7.33; 95% CI, 1.09-50.29; P = .04) were independent predictors of the prolongation of intrinsic QRS duration. CONCLUSIONS: The present study indicated that chronic RVA pacing may lead to a prolongation of intrinsic QRS duration, which could be independently predicted by elderly age, chronic RVA pacing, and the presence of coronary artery disease.

[A 10 years review of the characteristics of in-hospital ventricular fibrillation victim in a single center].

OBJECTIVE: To study the factors influencing the outcome of patients suffering from in-hospital ventricular fibrillation (IHVF), as there have been few studies focusing on this topic. METHODS: Patients with IHVF collected in a single cardiac center were classified into a successful group and a failure group. Data relevant to the predicting factors of the two groups were compared. RESULTS: There were 206 events in the analysis. The most common underlining disease was coronary artery disease (CAD), especially acute myocardial infarction (AMI). On multiple logistic regression analysis, it was shown that the independent predictors for failure of defibrillation were higher NYHA class (OR 1.7, 95% CI 1.3 - 2.2, P < 0.001), higher blood potassium level (OR 2.9, 95% CI 1.9 - 4.3, P = 0.007) and adrenaline usage (OR 25.0, 95% CI 11.5 - 55.1, P < 0.001). In a AMI sub-group, 56.9% of the IHVF events occurred within the first day of AMI, and the occurrence descended with time going on within 2 weeks. Before the occurrence of IHVF, the patients with right coronary artery as the infarction related artery (IRA) often suffered from (8/9, 88.9%) bradycardia (R-R interval > 1 s), but those with left anterior descending artery as IRA often showed (8/12, 66.7%) tachycardia (RR interval < 0.6 s). CONCLUSIONS: The common disease causing IHVF is CAD. The worse the heart function, the higher the rate of IHVF and the worse the prognosis. It IHVF not induced by hypokalemia and use of adrenaline in resuscitation predict lower successful defibrillation rate.

[Net carbon exchange and its driving factors of Haloxylon ammodendron plantation in the oasis-desert ecotone of Minqin, China]. / 民勤绿洲-è’æ¼ è¿‡æ¸¡å¸¦æ¢­æ¢­äººå·¥æž—å‡€ç¢³äº¤æ¢åŠå ¶å½±å“å› å­.

Carbon fluxes in a Haloxylon ammodendron plantation in the oasis-desert ecotone of Minqin was measured using an eddy covariance system. To provide scientific data for carbon source/sink assessment, we quantitatively analyzed the characteristics of CO2 flux and its driving factors in the growing season from May to October, 2018. The results showed that the trend of daily net carbon exchange in the growing season followed a symmetrical "U" shape curve. As to seasonality, bimodal curve was obvious. The plantation ecosystem was a carbon sink every month. The total carbon sequestrated was 34.38 g C·m-2, with the peak of 12.31 g C·m-2 in September and the lowest value of 0.89 g C·m-2 in July. The net carbon exchange in this ecosystem increased during the daytime with the increasing photosynthetically active radiation, consistent with the Michaelis-Menten rectangular hyperbola change. When the vapor pressure deficit was greater than 2.5 kPa, the increasing trend tended to flat. Ecosystem respiration increased exponentially with temperature, with temperature sensitivity being 1.7. Net carbon exchange in either day or night was significantly correlated with soil temperature through the whole growing season.

The morphology changes in limb leads after ablation of verapamil-sensitive idiopathic left ventricular tachycardia and their correlation with recurrence.

OBJECTIVES: This study was designed to explore the morphology changes in limb leads of ECGs after successful ablation of verapamil sensitive idiopathic left ventricular tachycardia (ILVT) and their correlation with tachycardia recurrence. METHODS: Between January 2001 and December 2006, 116 patients who underwent successful ablation of ILVT were included in the study. Twelve-lead surface ECG recordings during sinus rhythm were obtained in all patients before and after ablation to compare morphology changes in limb leads. RESULTS: The ECG morphology changes after ablation were divided into two categories: one with new or deepening Q wave in inferior leads and/or disappearance of Q wave in leads I and aVL, and the other without change. The changes in any Lead II, III, or aVF after ablation occurred significantly more in patients without recurrence of ventricular tachycardia (VT) (P < 0.0001, 0.002, and 0.0001, respectively). The patients with recurrence of VT tended to have no ECG changes, compared with those without recurrence of VT (P = 0.009). The sensitivity of leads II, III, and aVF changes in predicting nonrecurrence VT were 66.7%, 78.7%, and 79.6%, specificity were 100%, 75%, and 87.5%, and nonrecurrence predictive value of 100%, 97.7%, and 98.9%, respectively. When inferior leads changes were combined, they could predict all nonrecurrence patients with 100% specificity. CONCLUSIONS: Successful radiofrequency ablation of ILVT could result in morphology changes in limb leads of ECG, especially in inferior leads. The combined changes in inferior leads can be used as an effective endpoint in ablation of this ILVT.

[Time lag characteristics of the stem sap flow of Haloxylon ammodendron in the Minqin oasis-desert ectone, China.] / æ°‘å‹¤ç»¿æ´²è’æ¼ è¿‡æ¸¡å¸¦æ¢­æ¢­æ ‘å¹²æ¶²æµçš„æ—¶æ»žç‰¹å¾.

The stem sap flow rate of Haloxylon ammodendron plantation in the Minqin oasis-desert ectone was measured by the thermal dissipation probe (TDP). A cross-correlation analysis was used to estimate the time lag between the stem sap flow and the environmental factors influencing transpiration, including photosynthetically active radiation (PAR) and water vapor pressure deficit (VPD). The results showed that the stem sap flow rate of H. ammodendron had substantial seasonal variation, with the monthly average sap flow being the highest in June and the lowest in August. There was an obvious time lag between the stem sap flow of H. ammodendron and PAR and VPD. The stem sap flow was lagged behind PAR for 80 min but it was ahead of VPD for 114 min. Additionally, the time lag exhibited significant difference among different months during the growth season from May to September. The sap flow of H. ammodendron was more dependent on the variation of PAR on the daily scale than VPD, but it was more closely related to VPD during the day time. The time lag between the stem sap flow and PAR/VPD had no significant correlation with the tree factors (including plant height, ground diameter, diameter at 50 cm height, under branch height, canopy size) and the nocturnal sap flow.

Blockade of renin-angiotensin system: a supplementary treatment for circumferential pulmonary vein isolation in treating persistent atrial fibrillation.

The development of atrial fibrillation ablation has revolutionized the field of antiarrhythmic treatment by reducing the recurrence of atrial fibrillation (AF) significantly in patients with paroxysmal atrium fibrillation (PAF). However, the effect of ablation on the patients with persistent atrial fibrillation (PeAF) is not as good as it on PAF. Although doctors have created a series of ablation strategy, they still cannot treat PeAF effectively. This phenomenon is caused by structural remodeling and electrical remodeling of atrium during the long period of AF. Many experimental have demonstrated remodeling of atrium correlated with high level of angiotensin in atrial tissue, and blockade of renin-angiotensin system (RAS) through angiotensin-converting-enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) can reverse atrial remodeling. Clinical studies also confirmed that blockade of RAS can prevent AF effectively. Thus, for the object of treating PeAF effectively, we can combine the circumferential pulmonary vein isolation with blockade of RAS treatment, this combined strategy eliminate the trigger (pulmonary vein potential ) of AF and reverse the atrial remodeling, may be have a good effect on PeAF.

Radiofrequency catheter ablation of permanent atrial fibrillation under guidance of carto-merge technique.

OBJECTIVE: To investigate the feasibility and effectiveness of radiofrequency catheter ablation (RFCA) to treat per-manent atrial fibrillation (AF) under the guidance of Carto-Merge technique. METHODS: Fifteen male patients with permanent AF underwent RFCA under the guidance of Carto-Merge technique. The mean age was 54.00 +/- 10.44 years, and duration of AF was 23.66 +/- 14.93 months. Cardiac magnetic resonance angiography (MRA) was performed to obtain pre-procedural three-dimensional (3D) images on the anatomy of left atrium (LA) and pulmonary veins (PVs) before RFCA procedure. Then the electroanatomical map was integrated with 3D images of MRA to form Carto-Merge map that guided step-by-step ablation strategy of permanent AF. Circumferential PV ablation was performed first until complete PVs electric isolation confirmed by Lasso catheter. If AF was not terminated, lesion lines on roof of LA, mitral isthmus, and tricuspid isthmus were produced. RESULTS: The episodes of AF were terminated during RFCA in 2 patients, by direct current cardioversion in the remaining 13 patients. Transient AF occurred in 2 patients after ablation on 1st day and 1st week respectively, AF terminated spontaneously not long after taking metoprolol. One patient developed persistent atrial flutter (AFL) in 2 months after procedure and AFL was eliminated by the second ablation. Persistent AF recurred on 1st day, 1st and 5th week respectively in 3 patients, and did not terminate after 3 months even though amiodarone was given. The remaining 12 patients were all free of AF during 2-11 months of follow-up. The recent success rate for RFCA of permanent AF was 80%. CONCLUSIONS: Carto-Merge technique can effectively guide RFCA of permanent AF. When combined with single Lasso mapping, it can simplify the mapping, lower expenses, and enhance the success rate of RFCA of permanent AF.