Impact of land use history on the arbuscular mycorrhizal fungal diversity in arid soils of Argentinean farming fields.

Arbuscular mycorrhizal fungi (AMF) are a key soil functional group, with an important potential to increase crop productivity and sustainable agriculture including food security. However, there is clear evidence that land uses, crop rotations and soil features affect the AMF diversity and their community functioning in many agroecosystems. So far, the information related to AMF biodiversity in ecosystems like the Argentinean Puna, an arid high plateau where plants experience high abiotic stresses, is still scarce. In this work, we investigated morphological and molecular AMF diversity in soils of native corn, bean and native potato Andean crops, under a familiar land use, in Chaupi Rodeo (Jujuy, Argentina), without agrochemical supplements but with different histories of crop rotation. Our results showed that AMF morphological diversity was not only high and variable among the three different crop soils but also complemented by Illumina MiSeq data. The multivariate analyses highlighted that total fungal diversity is significantly affected by the preceding crop plants and the rotation histories, more than from the present crop species, while AMF communities are significantly affected by preceding crop only in combination with the effect of nitrogen and calcium soil concentration. This knowledge will give useful information on appropriate familiar farming.

[HIS bundle pacing : Far more than an ECG cosmetic effect]. / HIS-Bundle-Pacing : Weit mehr als EKG-Kosmetik.

The therapy for heart failure in patients with uncompromised systolic ventricular function (HfpEF) is still challenging because there is an obvious lack of effective therapy options. Several of these particular patients are additionally presenting atrioventricular (AV) block. In these patients HIS bundle pacing could be a hopeful therapy strategy due to the option of an AV resynchronisation as illustrated in the following case.

Catheter ablation in ASymptomatic PEDiatric patients with ventricular preexcitation: results from the multicenter "CASPED" study.

BACKGROUND: As there are limited data about the clinical practice of catheter ablation in asymptomatic children and adolescents with ventricular preexcitation on ECG, we performed the multicenter "CASPED" (Catheter ablation in ASymptomatic PEDiatric patients with Ventricular Preexcitation) study. METHODS AND RESULTS: In 182 consecutive children and adolescents aged between 8 and 18 years (mean age 12.9 ± 2.6 years; 65% male) with asymptomatic ventricular preexcitation, a total of 196 accessory pathways (APs) were targeted. APs were right sided (62%) or left sided (38%). The most common right-sided AP location was the posteroseptal region (38%). Ablation was performed using radiofrequency (RF) energy (93%), cryoablation (4%) or both (3%). Mean procedure time was 137.6 ± 62.0 min with a mean fluoroscopy time of 15.6 ± 13.8 min. A 3D mapping or catheter localization system was used in 32% of patients. Catheter ablation was acutely successful in 166/182 patients (91.2%). Mortality was 0% and there were no major periprocedural complications. AP recurrence was observed in 14/166 patients (8.4%) during a mean follow-up time of 19.7 ± 8.5 months. A second ablation attempt was performed in 20 patients and was successful in 16/20 patients (80%). Overall, long-term success rate was 92.3%. CONCLUSION: In this retrospective multicenter study, the outcome of catheter ablation for asymptomatic preexcitation in children and adolescents irrespective of antegrade AP conduction properties is summarized. The complication rate was low and success rate was high, the latter mainly depending on pathway location. The promising results of the study may have future impact on the ongoing risk-benefit discussion regarding catheter ablation in the setting of asymptomatic preexcitation in children and adolescents.

[Congenital heart defects in adulthood : Supraventricular tachycardia]. / Angeborene Herzfehler im Erwachsenenalter : Supraventrikuläre Tachykardien.

Supraventricular tachycardia (SVT) based on congenital substrates, such as accessory pathways or dual atrioventricular nodal properties, occur with an increased probability linked to specific congenital heart defects (CHDs). In the literature, the association of Ebstein's anomaly with accessory pathways and with Mahaim fibers is most prominent. Compared with patients with otherwise normal hearts, the clinical relevance of SVT is typically more severe and therefore antiarrhythmia treatment is a necessity in many cases. Diagnostics, pharmaceutical treatment, and interventional therapy of SVT in patients with CHD are often demanding owing to anatomical, hemodynamic, and electro-anatomical peculiarities. The use of antiarrhythmic medication is often limited because of intolerable side effects and a lack of reliability in suppressing arrhythmia relapses in the long term. Within the last 15-20 years catheter ablation has thus become established as the first-choice treatment for SVT, even in patients with CHD. However, rates of success, recurrence, and risks are still inferior to those observed in patients with a normally functioning heart owing to the co-existence of vascular and cardiac anomalies, surgically created alterations, an unusual electro-anatomy, and lower tolerance to hemodynamic changes. Successful treatment in patients with CHDs and SVT requires a deep understanding and knowledge of all the disciplines discussed above and should only be practiced in dedicated centers, as patient numbers are small and therefore experience is limited.

Radiofrequency catheter ablation of tachycardia in patients with congenital heart disease.

Patients with anomalies of the heart frequently suffer from arrhythmias that either are associated with a congenital heart defect or result from the course of the disease. For most of the bradyarrhythmias, appropriate timing of the initiation of treatment is more challenging than its eventual execution. In the case of tachycardias, technical aspects of treatment require more attention because the often imperative impact such tachycardias have on quality of life, morbidity, and mortality determine intervention timing. Increasingly, interventional electrophysiology is turned to as a potentially definitive and substrate-related treatment because of antiarrhythmic drug therapy's failure to prevent arrhythmia recurrences and the potential detrimental side effects from drug therapy seen in this particular patient population. Using the experience gained during the past 10 years in the treatment of patients with arrhythmias but without associated structural heart disease, several groups reported their results and difficulties with the application of such therapy to patients with congenital heart defects. In this report, we summarize our hospital's experience with transcatheter radiofrequency current application for treatment of various types of tachyarrhythmias in 139 children and adults with congenital heart defects, emphasizing the current limitations of such therapy and addressing the potential benefits expected from future technology. Patient ages ranged from 5 months to 76 years (mean 25.3 +/- 17.7 years), including 56 children and adolescents less than 16 years of age. At least one attempt at surgical palliation or correction was made in 93 patients; the remaining 46 patients had no surgical intervention attempts. A total of 225 different tachycardias were found, 93 of which were based on a congenital arrhythmogenic substrate (e.g., an accessory pathway). Acquired substrates (e.g., scars or myocardial fibrosis) gave rise to the remaining 132 tachycardias. Radiofrequency current ablation (183 sessions) successfully treated 121 of 139 patients. Within a follow-up period of 21 months a recurrence of the intrinsically treated tachycardia was seen in 24 patients (10.7%); 13 of the 24 underwent a successful repeat session. There were no significant procedure-related complications. Young and adult patients with congenital heart disease can be safely and successfully treated for tachycardias with the use of radiofrequency current ablation. Because such treatment meets the specific needs of this patient group, early consideration for this therapy is recommended.

Ebstein's anomaly in adults. Arrhythmias: diagnosis and therapeutic approach.

UNLABELLED: Patients with Ebstein's anomaly (M.E.) are known to have a high potential for developing arrhythmia, in the vast majority, of the tachycardia type. Most of these tachycardias are based on accessory pathways (AP) located along the anomalous atrioventricular valve, found in up to 30% of this patient cohort. Next to this main representative for congenital arrhythmogenic substrates, various types of acquired tachycardia were found in patients with M.E., such as atrial ectopic tachycardia (AET), atrial flutter (A. Flutt.), atrial reentry tachycardia (ART), atrial fibrillation and ventricular tachyarrhythmia. Refractoriness to medical treatment and a higher potential for side effects in these patients resulted in an increasing referral to interventional electrophysiology recent years. A total of 37 patients with M. E. and tachycardia underwent an attempt for radiofrequency current (RFC) treatment at our institution, 30 of whom were adults aged 18 to 61 yrs (33 +/- 12.2. yrs). Just 4 patients under went surgery for reconstruction of the anomalous valve and closure of an ASD (2 patients), in whom a total of 6 cases of atrial tachycardia were found, 3 common A. Flutt. and 3 atriotomy-scar related ART. Of the 26 unoperated patients, one presented with typical AV-nodal reentry tachycardia and the remaining patients with atrioventricular reentry tachycardia, based on a total of 39 APs. 27/39 Aps had bidirectional conduction properties, causing the WPW syndrome in 16 patients, 8 APs were concealed and the remaining 4 were Mahaim fibers. Within 39 sessions, 26 of the 30 patients were successfully treated by RFC ablation of the arrhythmogenic substrates. Mean session duration lasted for 313 +/- 151 min (range 95 to 660 min), and a fluoroscopy time of 56.0 +/- 38.4 min (2.2 to 146.8 min) was required. There were no severe acute complications. CONCLUSIONS: In patients with M. E. not only a high potential for the development of tachycardia, but also a tendency towards multiple arrhythmogenic substrates in the single patient can be ascertained. RFC ablation can be used safely and effectively for treatment for various types of tachycardias in patients with M. E.. Such therapy carries the potential for a definitive treatment and should be taken early into consideration as it meets the requirements this patient cohort.

Apical hypertrophic cardiomyopathy due to a de novo mutation Arg719Trp of the beta-myosin heavy chain gene and cardiac arrest in childhood. A case report and family study.

Hypertrophic cardiomyopathy (HCM) is a myocardial disease with variable phenotpye and genotype. To demonstrate that the mutation Arg719Trp in the cardiac beta-myosin heavy chain (beta MHC) gene is a high risk factor for sudden death and can be associated with an unusual apical non-obstructive HCM, we report the case of a 6 1/2 year old boy, who suffered cardiac arrest. The proband had a de novo mutation of the beta MHC gene (Arg719Trp) on the paternal beta MHC allele and a second maternally transmitted mutation (Met349Thr), as was shown previously (Jeschke et al. 1998 (11)). Here we report the clinical phenotype of the proband and of his relatives in detail. The proband had a marked apical and midventricular hypertrophy of the left and right ventricle without obstruction. There was an abnormal relaxation of both ventricles. Holter monitoring detected no arrhythmia. Ventricular fibrillation was inducible only by aggressive programmed stimulation. The boy died 3 1/2 years later after another cardiac arrest due to arrhythmia. Five carriers of the Met349Thr mutation in the family were asymptomatic and had no echocardiographic changes in the heart, suggesting a neutral inherited polymorphism or a recessive mutation. It is concluded that there is an association of the mutation Arg719Trp in the beta-myosin heavy chain with sudden cardiac death in a young child. Disease history in conjunction with the genetic analysis suggests that the implantation of a defibrillator converter would have been a beneficial and probably life saving measure.

Modification of the substrate for maintenance of idiopathic human atrial fibrillation: efficacy of radiofrequency ablation using nonfluoroscopic catheter guidance.

BACKGROUND: Catheter ablative techniques to modify the substrate to maintain atrial fibrillation (AF) require the creation of continuous radiofrequency current-induced ablation lines. This study was designed to assess the efficacy and safety of nonfluoroscopic mapping in this setting. METHODS AND RESULTS: A total of 45 consecutive patients with idiopathic AF were studied. The first 13 underwent ablation confined to the left atrium by creating a circular line isolating the pulmonary vein ostia and a second line connecting the former with the mitral annulus. Subsequently, 12 of these patients underwent a procedure confined to the right atrium (RA), where attempts were made to create an isthmus line between the inferior vena cava and the tricuspid annulus, an anterior line connecting the tricuspid annulus with the superior vena cava, and an intercaval line between the ostia of the inferior and superior venae cavae. In the last 32 patients, only the RA approach was performed. Technical difficulties prevented the creation of the intended left atrial line pattern: all patients experienced recurrences. A 100% recurrence rate was also observed after subsequent RA ablation, despite creation of a complete line pattern in 4 of 12 patients. Of the final 32 patients, AF recurred in 94%; a complete ablation line pattern had been achieved in 18 patients (56%), 16 of whom had recurrences. CONCLUSIONS: The electroanatomically-guided creation of extended radiofrequency current lesions is technically feasible only in the RA. However, procedural success in the RA does not suppress recurrences of AF in the majority of patients.

[Arrhythmias in patients with congenital heart disease and their impact on prognosis]. / Arrhythmien bei Patienten mit angeborenen Herzfehlern und Bedeutung für die Prognose.

Patients with congenital heart disease have an increased chance to suffer from brady- as well as tachyarrhythmias. The impact of these on quality of life, morbidity and mortality is more often imperative as compared to heart-healthy individuals. The substrate for these may be either congenital or acquired. Improvements of the surgical management of these patients have led, on the one hand, to improved survival rates with prolonged life expectancy within the last 2 decades, which on the other hand provided the basis for a higher rate of acquired cardiac arrhythmias. Together, this not only challenges diagnostics and therapy but also the prognostic relevance of these arrhythmias. The therapeutic strategies and prognostic markers have until now mostly been based on retrospective studies limited by the low number of patients and inhomogeneous patient selection. Despite these limitations, an increased risk of sudden cardiac death has been substantiated for certain patient groups, e.g., those operated on by the Mustard- or Senning procedures in patients with transposition of the great arteries and patients operated on with correction of the tetralogy of Fallot. However, until now it has not been possible to identify reliable markers for establishing the risk on an individual basis within these patient cohorts. For achieving reliable data on the symptomatic and prognostic effects of present-day--as well as new-coming--therapeutic strategies, it is mandatory to perform prospectively based, randomized multicenter studies. Furthermore, the well-appreciated synergism of hemodynamically and primarily of arrhythmia-based effects on prognosis could potentially be divided into their relative weight to better guide appropriate, substrate-related therapy. In addition, this should help to get better estimates of the risk for sudden cardiac death in different, etiologically homogeneous, groups of patients with congenital heart disease.

Nonfluoroscopic endocardial catheter mapping of atrial fibrillation.

The treatment of drug-refractory atrial fibrillation (AF) remains one of the unsolved problems in cardiology. Surgical interventions have demonstrated that AF can be prevented by multiple incisions within both atria. Recently, this strategy has been translated into a catheter procedure. So far, the ablation approach is not based on individual electrophysiologic data, but constitutes only an anatomic approach. Further insight into the spatial and temporal distribution of the local electrograms during AF is needed. Electroanatomic maps acquired by sequential mapping over 45 seconds at each site during AF in six patients with paroxysmal AF were analyzed off-line. Electrograms were sampled at a mean of 36 +/- 12 sites in the left atrium of each patient. A total of 217 sites were sampled, of which 27.3% (59) represented type A (regular) AF, 9.7% (21) represented type B (totally irregular), and 63.1% (137) represented type C (mixture of type A and B) electrograms. The distribution was analyzed in 20 different segments of the left atrium, and a significantly higher incidence of type A electrograms was found in area 3 (upper lateral pulmonary vein) than at all other sites (P < 0.005). This observation needs further confirmation before any conclusion with regard to catheter ablation can be drawn, particularly because the analysis was based on bipolar recordings from a 4-mm tip electrode.

[High frequency current ablation of supraventricular tachyarrhythmias in congenital heart defects]. / Hochfrequenzstromablation supraventrikulärer Tachyarrhythmien bei angeborenen Herzfehlern.

Supraventricular tachycardia is a frequent cause of disease in patients with congenital heart defects and has a potentially high impact on quality of life, morbidity and mortality of this patient cohort. Conventional treatment often fails to avoid recurrences of tachycardia in a long-term perspective. Potential side effects of antiarrhythmic drugs include aggravation of heart disease related disturbances of impulse generation and conduction properties or negative inotropic effects on haemodynamically impaired ventricular chambers. For these reasons, interventional electrophysiology is increasingly used for the treatment of supraventricular tachycardias in patients with congenital heart disease. Until March 1998 a total of 83 patients with congenital heart defects underwent an attempt for radiofrequency current treatment of supraventricular tachycardias. Among these were 36 children with an age of 5 months to 15 years (8.2 +/- 4.6 years) and 4.7 grown ups with an age of 17 to 76 years (39.3 +/- 14.3 years). In a natural course or preoperative status of the congenital heart disease were 35 patients, while palliative or corrective surgery was performed in 48 patients. Supraventricular tachycardia was based on a total of 63 congenital arrhythmogenic substrates, among them were 53 accessory pathways, 4 Mahaim fibres, 5 functionally dissociated AV-nodes and an anatomically doubled specific conduction system including 2 distinct AV-nodes in one case. In the remaining patients with tachycardia based on acquired arrhythmogenic substrates there were 45 incisional atrial reentrant tachycardias, 15 atrial flutters of the common type and 6 ectopic atrial tachycardias. In a total of 105 sessions 78 of the 83 patients were successfully treated with the use of radiofrequency current ablation. There were no significant procedure related complications. Radiofrequency current ablation can be carried out safely and successfully for the treatment of supraventricular tachycardia in young and adult patients with congenital heart disease. As such therapeutic strategy meets the specific requirements of this patient cohort, early consideration for this therapy is recommended.

[Anatomic distribution, conduction properties and recurrences after ablation of multiple in comparison with single accessory conduction pathways]. / Anatomische Verteilung, Leitungseigenschaften und Rezidivverhalten nach Ablation von multiplen im Vergleich zu singulären akzessorischen Leitungsbahnen.

In 1076 consecutive patients referred for radiofrequency current catheter ablation, the anatomical distribution and conduction properties of accessory pathways (APs) as well as the mode of recurrence after ablation were retrospectively analyzed and compared in patients with multiple and single APs. Except for 17 patients with Ebstein's anomaly, the prevalence of patients of multiple APs in this cohort was 5.4%. Patients with multiple APs. as opposed to patients with a single AP, had significantly more often APs located on the right free wall (23% versus 10%) and--since the prevalence of septal APs was identical in both groups--less frequently APs located on the left free wall (44% versus 56%). Also, concealed APs were significantly more often encountered in patients with multiple APs (45% versus 24%). Recurrence of conduction across an AP which had presumably been ablated was observed in both groups with statistically equal incidence of < 5%. In 11 patients with multiple APs, the additional AP was only found at the repeat session. These "new" APs were mostly concealed (9 out of 11) and necessitated an intervention predominantly late after the initial ablation session. Intermittent concealed conduction appears to be a likely explanation for this phenomenon. Patients with multiple APs exhibit a higher incidence of right free-wall and concealed APs, yet they stand the same, approximately 95%, chance of cure as do patients with a single AP. Nearly 25% percent of repeat sessions in patients initially thought to have a single AP are caused by the late manifestation of an additional AP.

Catheter-induced mechanical conduction block of right-sided accessory fibers with Mahaim-type preexcitation to guide radiofrequency ablation.

BACKGROUND: Accessory pathways originating at the tricuspid annulus that exhibit decremental antegrade conduction properties (Mahaim-type preexcitation) are amenable to radiofrequency (RF) current catheter ablation. However, a reliable and reproducible strategy for mapping and ablation of these fibers is lacking. METHODS AND RESULTS: Eleven patients with preexcited atrioventricular tachycardia involving a decrementally conducting antegrade accessory pathway underwent complete electrophysiological evaluation and subsequent attempts at RF catheter ablation. Mechanical conduction block at the subannular level of the atrial input to the accessory fiber was induced by catheter manipulation in 8 patients, in 2 of them during atrial fibrillation. RF current was delivered, after resumption of preexcitation, to the site of mechanical block during atrial pacing (n = 6) or atrial fibrillation (n = 2) and eliminated the accessory pathway in all 8 patients. In another patient, mechanical block was not observed, but ablation of the atrial accessory fiber insertion was achieved at the subannular level during atrioventricular tachycardia. The anatomic site of ablation along the tricuspid annulus was anterolateral (n = 1), lateral (n = 3), or posterolateral (n = 5). Failures were encountered in the first patient of the series in whom ablation attempts were directed at the ventricular insertion of the accessory fiber and in a patient in whom ablation of the atrial insertion was attempted at the supraannular level. Recurrence of preexcitation within 12 hours was observed in 5 of 6 patients in whom ablation had been achieved during atrial pacing. Eventually successful repeat sessions were performed the following day using a simplified ablation approach. Thus, a median of 5 RF pulses (range, 1 to 26) per accessory fiber eliminated conduction in 9 (82%) of the 11 patients in 1.9 +/- 0.9 sessions. During a follow-up of 9.5 +/- 2.3 months, preexcitation recurred in 1 patient. CONCLUSIONS: The atrial origin of accessory connections with Mahaim-type preexcitation is apparently confined to the anterolateral-to-posterolateral region of the tricuspid annulus. Mechanical conduction block in the atrial input to the accessory fiber induced at the subannular level by catheter manipulation provides an optimal marker to locate the ablation site, even during atrial fibrillation. To expose early recurrence of antegrade accessory pathway conduction, intermittent atrial pacing in the 12 hours after ablation is advisable; in cases of recurrence, a repeat procedure can readily be performed using just the ablation catheter advanced to the target site at the tricuspid annulus.

Potential of intracardiac ultrasonography as an adjunct for mapping and ablation.

Radio frequency catheter ablation of cardiac tissues has evolved rapidly as the standard therapy for various arrhythmias. Current mapping techniques include fluoroscopy and endocardial ECG recordings. These techniques are time-consuming and give only limited information with regard to cardiac anatomy and pathology. Moreover, fluoroscopy leads to significant radiation exposure to the patient and the operator. Intracardiac ultrasonography is a promising new technique that may improve intracardiac anatomic orientation, reduce radiation exposure, allow better control of lesion formation during radio frequency current application, and identify possible complications such as thrombus formation or perforation. Intracardiac ultrasonography systems that are presently available are limited by insufficient penetration depth and image resolution. Technical refinements are discussed that may improve the applicability of intracardiac echocardiography for electrophysiologic mapping procedures.

[Successful high-frequency current ablation of three accessory conduction pathways in a single session]. / Erfolgreiche Hochfrequenzstromablation von drei akzessorischen Leitungsbahnen in einer Sitzung.

A case is presented of a 25-year-old symptomatic male with Wolff-Parkinson-White syndrome and three overt accessory atrioventricular connections which were all diagnosed and ablated during the same session. A discordant preexcitation pattern between delta wave and QRS axis was found on the surface electrocardiogram, indicating the presence of two or more accessory pathways. During atrial pacing the appearance of a changing QRS morphology and alternating delta wave suggested the presence of an additional left-sided pathway. After ablation of a right anteroseptal pathway, a second pathway was found located in the left lateral position and was successfully ablated. The final pathway became evident only after the ablation of the first two and was found to be located in a right midseptal position. This pathway was also ablated during this session. There were no complications and the patient remained asymptomatic during an 11-month follow-up.

[Combined surgical-interventional procedure in congenital heart defects with postoperative, left ventricular dysfunction]. / Kombiniertes operativ-interventionelles Vorgehen bei angeborenen Herzfehlern mit postoperativer, linksventrikulärer Dysfunktion.

Creation of a communication between the left and right atrium to decompress the left ventricle can be life-saving after corrective surgery in some patients with congenital heart disease and small left ventricle. After adaptation of the left ventricle, surgical closure of this anastomosis becomes mandatory. We report four patients (2.9 to 8.2 kg) where non-surgical, transcatheter-closure was performed in the first year of life using the Rashkind-PDA-Occluder System (USCI). In a newborn with d-transposition of the great arteries (2.9 kg), in a patient with atrial septal defect (5.1 kg), and in a patient with tetralogy of Fallot with atrial septal defect (4.9 kg) atrial septal defects were not completely closed during correction because of left-ventricular dysfunction. Five to 12 days postoperatively transcatheter closure was performed utilizing the 8F-Rashkind-PDA-Occluder System in the first two patients (2.9 kg and 4.9 kg) and by use of the 11F-Rashkind-PDA-Occluder System in the third patient (4.9 kg). In the patient with supracardiac total anomalous pulmonary venous drainage via a vertical vein, the vertical vein was not closed during surgical correction at the age of 2 months. Transcatheter closure was performed 6 months later using the 11F-Rashkind-PDA-Occluder-System. It is concluded that small, defined atrial septal defects can be closed, even in newborns, using the Rashkind-PDA-Occluder System (USCI) and, furthermore, that large vessels, even without luminal narrowing can be occluded completely. Thus, this combined "surgical-interventional approach" is not limited by age and could reduce the risk of surgical correction in patients with congenital heart disease and small left ventricle.