Search

Background Pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) has become an established and widespread procedure for the treatment of symptomatic paroxysmal and persistent atrial fibrillation (AF). The safety and efficacy of PVI at low and medium volume hospitals is unknown. Aim To determine safety and acute efficacy of PVI using CBA performed at community hospitals with limited annual case numbers. Methods This registry study prospectively included 1004 consecutive patients who underwent PVI with CBA for symptomatic paroxysmal (n=563) or persistent AF (n=441) between 01/2019 and 09/2020 at 20 community hospitals (each performing Results The mean annual number of CBA procedures performed was 59±26/hospital, the mean annual number of PVI performed regardless of the method used was 70±26/center. 8/20 hospitals performed CBA only. There were 22 operators (1,1/center), in 12/20 hospitals CBA was performed by an operator being board certified in invasive electrophysiology. 10/20 hospitals included 60 patients/hospital included a total of 623 pts (62%). Mean procedure time was 90.1±31.6 min, mean fluoroscopy time was 19.2±11.4 min. Isolation of all pulmonary veins could be achieved in 97.9% of patients. Not achieving the goal of “all veins isolated” in a respective patient was mainly due to early termination of CBA procedure due to phrenic nerve palsy. Major complications occurred in 1,2% of patients: no in-hospital death (0%), clinical stroke in 2 patients (0.2%), pericardial effusion requiring pericardial drainage in 2 patients (0,2%), vascular complications needing vascular surgery and/or blood transfusion in 2 patients (0,2%), phrenic nerve palsy persisting up to hospital discharge in 6 patients (0,6%). Minor complications occurred in 7,5% of patients: pericardial effusion with no need of intervention in 0,4%, access site complications with no need for therapeutic intervention or prolonged in-hospital stay in 2,1% (mainly superficial hematoma) and phrenic nerve palsy resolving before discharge in 4,2%. No significant difference in the number of complications could be found when testing for numbers of enrolled patients (> or < than 60/hospital) or regarding the board certification status of the operator. Conclusions PVI for paroxysmal or persistent AF using CBA can be performed at community hospitals with high acute efficacy and low complication rates despite low and moderate annual procedure numbers. Funding Acknowledgement Type of funding sources: None.

Background: Atrial arrhythmias are common in patients with implantable cardioverter-defibrillator (ICD). External shocks and internal cardioversion through commanded ICD shock for electrical cardioversion are used for rhythm-control. However, there is a paucity of data on efficacy of external versus internal cardioversion and on the risk of lead and device malfunction. We hypothesized that external cardioversion is noninferior to internal cardioversion for safety, and superior for successful restoration of sinus rhythm. Methods: Consecutive patients with ICD undergoing elective cardioversion for atrial arrhythmias at 13 centers were randomized in 1:1 fashion to either internal or external cardioversion. The primary safety end point was a composite of surrogate events of lead or device malfunction. Conversion of atrial arrhythmia to sinus rhythm was the primary efficacy end point. Myocardial damage was studied by measuring troponin release in both groups. Results: N=230 patients were randomized. Shock efficacy was 93% in the external cardioversion group and 65% in the internal cardioversion group ( P Conclusions: This is the first randomized trial on external vs internal cardioversion in patients with ICDs. External cardioversion was superior for the restoration of sinus rhythm. The unmasking of silent lead malfunction in the internal cardioversion group suggests that an internal shock attempt may be reasonable in selected ICD patients presenting for electrical cardioversion. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03247738.

Funding Acknowledgements Type of funding sources: None. OnBehalf REGIONAL Background Pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) has become an established procedure for the treatment of symptomatic paroxysmal and persistent atrial fibrillation (AF). The safety and efficacy of PVI at community hospitals with low to moderate case numbers is unknown. Aim To determine safety and efficacy of PVI using CBA performed at community hospitals with limited annual case numbers. Methods 1004 PVI performed consecutively between 01/2019 and 09/2020 at 20 community hospitals (each Results Mean number of PVI using CBA/year was 59 ± 26. Mean procedure time was 90.1 ± 31.6 min and mean fluoroscopy time was 19.2 ± 11.4 min. Isolation of all pulmonary veins could be achieved in 97.9% of patients, early termination of CBA due to phrenic nerve palsy was the most frequent reason for incomplete isolation. There was no in-hospital death. 2 patients (0.2%) suffered a clinical stroke. Pericardial effusion occurred in 6 patients (0.6%), 2 of them (0.2%) required pericardial drainage. Vascular complications occurred in 24 patients (2.4%), in 2 of these patients (0.2%) vascular surgery was required. In 48 patients (4.8 %) phrenic nerve palsy was noticed which persisted up to hospital discharge in 6 patients (0.6%). Conclusions PVI for paroxysmal or persistent AF using CBA can be performed at community hospitals with high efficacy and low complication rates despite low to moderate annual procedure numbers.

Aims Pulmonary vein isolation (PVI) using cryoballoon ablation (CBA) is an established procedure for treating symptomatic paroxysmal and persistent atrial fibrillation (AF). The safety and efficacy of PVI performed at community hospitals are unknown. We aimed to determine the safety and acute efficacy of PVI using CBA performed at community hospitals with limited annual case numbers. Methods and results This registry study included 1004 consecutive patients who had PVI performed for symptomatic paroxysmal (n = 563) or persistent AF (n = 441) from January 2019 to September 2020 at 20 hospitals. Each hospital performed fewer than 100 CBA–PVI procedures/year according to local standards. Procedural data, efficacy, and complication rates were determined. The mean number of CBA procedures performed/year at each centre was 59 ± 25. The average procedure time was 90.1 ± 31.6 min and the average fluoroscopy time was 19.2 ± 11.4 min. Isolation of all pulmonary veins was documented in 97.9% of patients. The most frequent reason for not achieving complete isolation was development of phrenic nerve palsy. No hospital deaths were observed. Two patients (0.2%) suffered a clinical stroke. Pericardial effusion occurred in six patients (0.6%), two of whom (0.2%) required pericardial drainage. Vascular complications occurred in 24 patients (2.4%), two of whom (0.2%) required vascular surgery. Phrenic nerve palsy occurred in 48 patients (4.8%) and persisted up to hospital discharge in six patients (0.6%). Conclusion Pulmonary vein isolation procedures for paroxysmal or persistent AF using CBA can be performed at community hospitals with high acute efficacy and low complication rates.

Aims Current guidelines recommend opportunistic screening for atrial fibrillation (AF) but the prognosis of individuals is unclear. The aim of this investigation is to determine prevalence and 1-year outcome of individuals with screen-detected AF. Methods and results We performed a prospective, pharmacy-based single time point AF screening study in 7107 elderly citizens (≥65 years) using a hand-held, single-lead electrocardiogram (ECG) device. Prevalence of AF was assessed, and data on all-cause death and hospitalization for cardiovascular (CV) causes were collected over a median follow-up of 401 (372; 435) days. Mean age of participants was 74 ± 5.9 years, with 58% (N = 4130) of female sex. Automated heart rhythm analyses identified AF in 432 (6.1%) participants, with newly diagnosed AF in 3.6% of all subjects. During follow-up, 62 participants (0.9%) died and 390 (6.0%) were hospitalized for CV causes. Total mortality was 2.3% in participants with a screen-detected AF and 0.8% in subjects with a normal ECG [hazard ratio (HR) 2.94; 95% confidence interval (CI) 1.49–5.78; P = 0.002]; hospitalization for CV causes occurred in 10.6% and 5.5%, respectively (HR 2.08; 95% CI 1.52–2.84; P, Graphical Abstract

Funding Acknowledgements The investigators received an unrestricted research grant by Pfizer/BMS. Pfizer/BMS was not involved in the planning, conduct, analysis, or interpreta Background Recently, various devices specifically designed to automatically detect atrial fibrillation, became available. Utility of automated atrial fibrillation detection in mass-screening remains unclear, because accuracy and validation of automated AF detection were mostly tested retrospectively in preselected cohorts with high atrial fibrillation prevalence. Purpose The aim of this analysis was to determine the accuracy of automated atrial fibrillation detection by a single-lead hand-held ECG device in a prospective population-based screening approach with several thousand subjects. Methods For automated atrial fibrillation detection, we investigated the MyDiagnostick a 30 cm long hand-held ECG-stick. All customers aged 65 years or older in the pharmacies were eligible to participate. After informed consent was obtained, a one-minute single-lead ECG was recorded by trained staff. Five levels of human ECG expert validation were performed to determine heart rhythm. All recorded unfiltered ECGs (Figure 1) were analyzed at least by two independent, blinded investigators, in case of an automated AF detection by at least 3 independent, blinded investigators. In case of contradiction in the first three levels of heart rhythm assessment, ECGs were analyzed in level 4 by two independent cardiologists. In level 5 all single-lead ECGs were unblinded and any single-lead ECG with a contradiction between the human ECG expert results and the automated ECG-Stick result were analyzed by a rhythm consortium consisting of 3 cardiologists. Final results for heart rhythm and ECG quality were stipulated by a hierarchical approach, whereas results in higher levels of analysis vote down results in earlier levels of analysis in case of a contradiction. Results In total, 7209 single-lead ECGs were available for analysis. The mean age was 74 ± 6 years, 42% (N = 3049) of participants were male, mean CHA2DS2-VASc score was 3.3 ± 1.4. We identified 5.3% (N = 383) patients with atrial fibrillation identified by human investigators. The ECG-Stick diagnosed 79% (N = 304) of the atrial fibrillation patients correctly. In 21% (N = 79/383) the result was false-negative, and in 1% (N = 72/7209) false-positive. In another 1% (N = 81/7209) single-lead ECG recordings were uninterpretable by expert investigators, although the automated analysis provided a result (SR: 27, atrial fibrillation: 54). Using final level results by expert ECG reading as reference, automated ECG-Stick analysis showed good prediction in receiver operating calculation of atrial fibrillation with an area under the curve of 0.89, sensitivity: 80%, specificity: 98%, and a good interclass correlation coefficient of 0.75, 95%CI (0.74; 0.76)). Conclusions The results encourage the implementation of single-lead ECG devices for automated atrial fibrillation screening. A rhythm diagnosis by single-lead ECG seems possible for recordings with excellent ECG signal quality. Abstract Figure. Single-lead ECG example (5 of 60 sec)

Background Atrial fibrillation (AF) is the most common arrhythmia associated with increased morbidity and mortality. Current guidelines recommend opportunistic screening for AF but the prognostic impact of screen-detected AF is unclear. Methods We performed a 4-week, prospective, pharmacy-based AF screening study in 7107 elderly citizens (≥65 years) using a hand-held, automated, one-minute single-lead ECG (SL-ECG) recording device. Prevalence and incidence of AF was assessed, and data on all-cause death and hospitalization for cardiovascular (CV) causes were collected over a median follow-up of 401 (372; 435) days. Results Automated SL-ECG analyses revealed heartbeat irregularities suspicious of AF in 432 (6.1%) participants with newly diagnosed AF in 3.6% of all subjects. During follow-up, 62 participants (0.9%) died and 390 (6.0%) were hospitalised for CV causes. Total mortality was 2.3% in participants with a SL-ECG suspicious of AF and 0.8% in subjects with a normal SL-ECG (HR 2.93; 95% CI: 1.49, 5.77; P=0.002, Figure 1A); hospitalization for CV causes occurred in 10.6% and 5.5%, respectively (HR 2.08; 95% CI: 1.52, 2.84; P Figure 1 Conclusions Pharmacy-based, automated, one-minute SL-ECG screening in elderly citizens identified subjects with unknown AF and an excess mortality risk over the next one year. Acknowledgement/Funding Unrestricted research grant by Pfizer/BMS. Matthias Zink received a DGK electrophysiology grant (funded by St. Jude Medical).

BioMed research international 2015, 840356 (2015). doi:10.1155/2015/840356, Published by Hindawi, New York [u.a.]

A simplification of Pijls’ formula to calculate the predicted fractional flow reserve (FFR) in sequential coronary stenosis without balloon inflation is hereby proposed. In patients with an indication for FFR and sequential coronary stenosis, FFR was recorded distally and between the lesions. The

Hochdruckerkrankungen tragen weltweit entscheidend zu Morbiditat und Mortalitat bei. Nach wie vor ist es fur den behandelnden Arzt eine besondere Herausforderung, den Patienten von der Notwendigkeit der Therapie einer haufig asymptomatischen Erkrankung zu uberzeugen. Vor der Therapieeinleitung ist eine basisdiagnostische Abklarung auch hinsichtlich des Vorliegens einer sekundaren (moglicherweise anders therapeutisch zuganglichen) Hypertonie essenziell. Insbesondere bei jungen Patienten als auch bei fehlender Nachtabsenkung sollte eine ausfuhrliche Abklarung mit Anamneseerhebung und Labordiagnostik sowie Abklarung einer renalen oder endokrinologischen Ursache erfolgen. Weitere Faktoren wie Lebensstil, fehlende Adharenz, aber auch eine Schlafapnoe sollten in die differenzialdiagnostischen Uberlegungen einbezogen werden. Zudem sollte das gesamte kardiovaskulare Risiko abgeschatzt werden durch Diagnose von anderen Risikofaktoren, Endorganschaden und Begleiterkrankungen.

Objective: Current alternative approaches for pacemaker lead implantation imply the breach of the pleural space. Recently, the feasibility of experimental lead implantation by rigid endoscopy has been described. The use of flexible endoscopes and a standardised application has not been realised yet. Our main goal was to compare rigid andflexible endoscopy and to establish a standardisedprotocol for the implementation of a closed-chest subxiphoid approach for epimyocardial lead implantation. Methods: Rigid and flexible endoscopes were used for placement of screw-in pacingleads (4-F). A total of 17 adult pigs (80 kg) were anaesthetised and a 10-mm subxiphoid axial incision performed. The pericardium was opened and entered under endoscopic vision. Epimyocardial electrodes were implanted through the endoscope onto all four chambers. Standard haemodynamic measurements and pacing measurements were carried out. Results: Both methods were deployed in the first three individuals. Superior endorsement of rigid endoscopy, due to better orientation and stability, led to its exclusive deployment in the remaining 14 individuals. Access to the implantation sites was quick (

Background— Electric stimulation of mediastinal sympathetic cardiac nerves increases cardiac contractility but is not selective for the left ventricle because it elicits sinus tachycardia and enhanced atrioventricular conduction. The aim of this study was to identify sympathetic neural structures inside the heart that selectively control left ventricular inotropy and can be accessed by transvenous catheter stimulation. Methods and Results— In 20 sheep, high-frequency stimulation (200 Hz) during the myocardial refractory period with electrode catheters inside the coronary sinus evoked a systolic left ventricular pressure increase from 97±20 to 138±32 mm Hg ( P P =0.004) and rate of diastolic relaxation (531±128 versus 888±331 mm Hg/s; P =0.001) increased. The slope of the end-systolic pressure-volume relationship increased (2.3±0.8 versus 3.1±0.6 mm Hg/mL; P =0.04), as did cardiac output (3.5±0.8 versus 4.4±0.8 L/min; P Conclusions— Cardiac nerve fibers that innervate the left ventricle are amenable to transvenous electric catheter stimulation. This may permit direct interference with and modulation of the sympathetic tone of the left ventricle.

Atrial fibrillation (AF), the most common arrhythmia, has a major impact on both patient morbidity and healthcare economics. Hospital admissions due to AF have risen by two-thirds in the last 20 years. This is due mainly to an aging population and an increasing prevalence of chronic heart disease. Strategies for the management of AF include prevention of thromboembolism, rate control and correction of the arrhythmia. Electrical cardioversion as one component of the treatment of AF requires the absence of atrial thrombi. Transesophageal echocardiography is used routinely for exclusion of atrial thrombi prior to cardioversion in many hospitals. This review presents preliminary data on the clinical use of devices for simultaneous transesophageal echocardiography and transesophageal cardioversion.

BioMed research international 2015, 810797 (2015). doi:10.1155/2015/810797, Published by Hindawi, New York [u.a.]

Objectives This study was designed to develop a technique to selectively increase the sympathetic tone to the heart by cardiac sympathetic nerve stimulation (SNS). Background Access to the cardiac sympathetic neurons may allow modulating the adrenergic tone of the heart while avoiding systemic side effects. Methods Cardiac sympathetic nerves course within neural sleeves along the subclavian artery. Because of this proximity, transvascular SNS was attempted with electrode catheters inside the subclavian artery in 16 pigs. Results Right/left (R-/L-) SNS (20 Hz) during ventricular pacing at 200/min evoked a >100% increase of left ventricular systolic pressure (baseline: 51 ± 1 mm Hg; L-SNS: 118 ± 26 mm Hg; R-SNS: 116 ± 33 mm Hg; p Conclusions The neural adrenergic tone to the heart can be selectively increased by catheter stimulation of cardiac efferent sympathetic nerves.

Journal of cardiothoracic surgery 9, 114 (2014). doi:10.1186/1749-8090-9-114, Published by BioMed Central, London

Background Cardiac parasympathetic nerves run alongside the superior vena cava (SVC) and accumulate particularly epicardially adjacent to the orifice of the coronary sinus (CS). In animals, these nerves can be electrically stimulated inside the SVC or CS, which results in negative chronotropic/dromotropic effects and negative inotropic effects in the atria but not the ventricles. Parasympathetic nerve stimulation (PS) with 20 Hz in the CS, however, also excites the atria, thereby inducing atrial fibrillation. The present study overcomes this limitation by applying high-frequency nerve stimuli within the atrial refractory period. Using this technique, we investigated for the first time whether neurophysiological effects similar to those in animals can be obtained in humans. Methods and Results In 25 patients, parasympathetic nerves were stimulated via a multipolar electrode catheter placed in the SVC (stimulation with 20 Hz; n=14) or CS (pulsed 200-Hz stimuli; n=11). A significant sinus rate decrease and prolongation of the antegrade Wenckebach period was achieved during PS in the SVC. During PS in the CS, a graded-response prolongation of the antegrade Wenckebach interval was observed with increasing PS voltage until third-degree AV block occurred in 8 of 11 patients. The negative chronotropic/dromotropic effects started and terminated immediately after the onset and termination of PS, respectively. Atropine abolished these effects (n=11). Conclusions Human parasympathetic efferent nerve stimulation induces reversible negative chronotropic and dromotropic effects. PS may serve as an adjunctive tool for the diagnosis/treatment of supraventricular tachycardias and may be beneficial for ventricular rate slowing during tachycardic atrial fibrillation in patients with congestive heart failure.

To the Editor: Despite great efforts and success in terminating ventricular tachycardia (VT) by methods like cardioversion and overdrive stimulation, there are situations in which VTs are ongoing (incessant VT) despite aggressive therapy. We assessed a stimulation technique for hemodynamic

Purpose Video-assisted pericardioscopic surgery (VAPS) for epimyocardial lead implantation has demonstrated positive acute results concerning the safety and degree of freedom inside the pericardium. We evaluated the employment of a newly developed trocar for pericardioscopy with regard to long-term effects and feasibility of reoperation. Description Eight adult sheep were divided into three groups. In two animals, VAPS was used exclusively. All other animals received four small-caliber epicardial leads through VAPS. After 6 and 12 months (n = 3 each), reoperation was conducted for reevaluation of entry site, intrapericardial adhesions, lead position, and morphology of the implantation site. Evaluation Reentry close to the previous entry site proves unproblematic. Adhesions were mild to moderate in the immediate area of the implanted leads. Throughout the follow-up, pacing parameters were satisfactory. Lead dislodgement occurred in 1 of 24 leads. The deployment of small-caliber flexible endoscopes through the new trocar provided sufficient navigation, stability, and maneuverability. Conclusions Reoperation from the same subxiphoid approach proved feasible. Lead removal and reimplantation were feasible at both 6 months and 12 months after initial implantation. The intrapericardial adhesions caused by VAPS alone are mild.

Anticoagulation represents the mainstay of therapy for most patients with atrial fibrillation. Patients on oral anticoagulation often require concomitant antiplatelet therapy, mostly because of coronary artery disease. After coronary stent implantation, dual antiplatelet therapy is necessary. However, the combination of oral anticoagulation and antiplatelet therapy increases the bleeding risk. Risk scores such as the CHA2DS2-Vasc score and the HAS-BLED score help to identify both bleeding and stroke risk in individual patients. The guidelines of the European Society of Cardiology provide a rather detailed recommendation for patients on oral anticoagulation after coronary stent implantation. However, robust evidence is lacking for some of the recommendations, and especially for new oral anticoagulants and new antiplatelets few or no data are available. This review addresses some of the critical points of the guidelines and discusses potential advantages of new anticoagulants in patients with atrial fibrillation after stent implantation.

Cardiac resynchronization therapy (CRT) is a therapeutic option for heart failure patients with a severely reduced left ventricular ejection fraction and left bundle branch block (Cleland et al., 2001). Ventricular resynchronization is achieved by biventricular pacing, usually via electrodes in the right ventricular apex and a left ventricular (LV) electrode positioned in a coronary vein. About one third of implanted patients do not respond to CRT (Derval et al., 2010). In order to reduce the percentage of non-responders, several strategies have been developed. They include optimization of patient selection, device programming as well as LV lead location. In cardiomyopathy with left bundle branch block, the lateral wall is the site of latest activation and should be the optimal location for LV pacing. Therefore, standard implantation sites for LV leads are lateral or posterolateral branches of the coronary sinus. Congruent to these pathophysiological findings, Butter et al. demonstrated a superiority of lateral wall pacing versus anterior wall pacing in CRT (Butter et al., 2001). However, a more detailed look at optimal pacing locations might be required to increase the effect of CRT and decrease non-responder rates. Different imaging modalities have been used to both identify optimal pacing sites as well as to plan LV lead implantation.

Rationale: Recently, we provided a technique of chronic high-frequency electric stimulation (HFES) of the right inferior ganglionated plexus for ventricular rate control during atrial fibrillation in dogs and humans. In these experiments, we observed a decrease of the intrinsic ventricular rate during the first 4 to 5 months when HFES was intermittently shut off. Objective: We thus hypothesized that HFES might elicit trophic effects on cardiac neurons, which in turn increase baseline parasympathetic tone of the atrioventricular node. Methods and Results: In mongrel dogs atrial fibrillation was induced by rapid atrial pacing. Endocardial HFES of the right inferior ganglionated plexus, which contains abundant fibers to the atrioventricular node, was performed for 2 years. Sham-operated nonstimulated dogs served as control. In chronic neurostimulated dogs, we found an increased neuronal cell size accompanied by an increase of choline acetyltransferase and unchanged tyrosine hydroxylase protein expression as compared with unstimulated dogs. Moreover, β-nerve growth factor (NGF) and neurotrophin (NT)-3 were upregulated in chronically neurostimulated dogs. In vitro, HFES of cultured neurons of interatrial ganglionated plexus from adult rats increased neuronal growth accompanied by upregulation of NGF, NT-3, glial-derived neurotrophic factor (GDNF), ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) expression. NGF was identified as the main growth-inducing factor, whereas NT-3 did not affect HFES-induced growth. However, NT-3 could be identified as an important acetylcholine-upregulating factor. Conclusions: HFES of cardiac neurons in vivo and in vitro causes neuronal cellular hypertrophy, which is mediated by NGF and boosters cellular function by NT-3–mediated acetylcholine upregulation. This knowledge may contribute to develop HFES techniques to augment cardiac parasympathetic tone.

Background— The occurrence of monomorphic ventricular tachycardia (M-VT) with >1 QRS morphology during the same episode (pleomorphism [PL]) or in different episodes (multiple morphologies [MM]) has been described through ECG. Implantable cardioverter-defribillator (ICD) electrograms (EGs) provide the opportunity to analyze virtually all spontaneous M-VT episodes. We sought to study the incidence, determinants, and prognostic significance of PL and MM as assessed by ICD-EG in a prospective series of patients with ICDs. Methods and Results— Spontaneous episodes of M-VT were analyzed before ICD intervention. PL was defined as >1 ICD-EG morphology, each having ≥6 consecutive identical beats during the same VT episode, and MM as >1 ICD-EG morphology in different M-VT episodes in the same patient. We analyzed 1881 M-VT episodes from 315 patients followed for 17 months. PL and MM occurred in 6% and 19%, respectively, of the total population (16% and 62% of patients with M-VT). Recurrent M-VT as diagnosis for ICD indication predicted PL and MM. Patients with PL more frequently developed MM (85% versus 15%; P P =0.009) and female sex (odds ratio, 3.1; P =0.038) predicted mortality. Conclusions— In a prospective series of patients with ICDs, mostly indicated for secondary prevention, both PL and MM of VT, as judged by ICD-EG, were not uncommon and were strongly associated. Female sex and the development of PL VT were the only independent predictors of mortality.

Background Sheep are routinely used in experimental cardiac electrophysiology and surgery. Objective The purpose of this study was to (1) ascertain the topography and architecture of the ovine epicardial neural plexus (ENP), (2) determine the relationships of ENP with vagal and sympathetic cardiac nerves and ganglia, and (3) evaluate gross anatomic differences and similarities of ENP in humans, sheep, and other species. Methods Ovine ENP and extrinsic sympathetic and vagal nerves were stained histochemically for acetylcholinesterase in whole heart and/or thorax-dissected preparations from 23 newborn lambs, with subsequent examination by stereomicroscope. Results Intrinsic cardiac nerves extend from the venous part of the ovine heart hilum along the roots of the cranial (superior) caval and left azygos veins to both atria and ventricles via five epicardial routes: dorsal right atrial, middle dorsal, left dorsal, right ventral, and ventral left atrial nerve subplexuses. Intrinsic nerves proceeding from the arterial part of the heart hilum along the roots of the aorta and pulmonary trunk extend exclusively into the ventricles as the right and left coronary subplexuses. The dorsal right atrial, right ventral, and middle dorsal subplexuses receive the main extrinsic neural input from the right cervicothoracic and right thoracic sympathetic T 2 and T 3 ganglia as well as from the right vagal nerve. The left dorsal is supplied by sizeable extrinsic nerves from the left thoracic T 4 –T 6 sympathetic ganglia and the left vagal nerve. Sheep hearts contained an average of 769 ± 52 epicardial ganglia. Cumulative areas of epicardial ganglia on the root of the cranial vena cava and on the wall of the coronary sinus were the largest of all regions ( P Conclusion Despite substantial interindividual variability in the morphology of ovine ENP, right-sided epicardial neural subplexuses supplying the sinoatrial and atrioventricular nodes are mostly concentrated at a fat pad between the right pulmonary veins and the cranial vena cava. This finding is in sharp contrast with a solely left lateral neural input to the human atrioventricular node, which extends mainly from the left dorsal and middle dorsal subplexuses. The abundance of epicardial ganglia distributed widely along the ovine ventricular nerves over respectable distances below the coronary groove implies a distinctive neural control of the ventricles in human and sheep hearts.

Aims Ventricular rate control is considered as an initial choice of therapy in many patients with atrial fibrillation (AF). We could previously show that electrostimulation of the right inferior ganglionated plexus (RIGP), which supplies the AV node, instantly decreases ventricular rate during AF. This study describes the development of a technique to reliably implant a chronic lead inside the RIGP. Methods and results In nine mongrel dogs with AF, the RIGP was identified by neuromapping with probatory high-frequency stimulation (20 Hz) over steerable electrode catheters until a significant ventricular rate slowing was achieved. Then an active fixation, permanent pacemaker lead was fixed closed to the mapping catheter left in place as anatomical marker. Initially ( n = 4) available guiding catheters and steerable lead stylets were employed to navigate and anchor the lead, which resulted in repetitive screw-in attempts. Therefore, a guiding catheter was developed, which allowed angiography, lead advancement through its lumen, and probatory neurostimulation over its tip. This tool allowed lead delivery within 40 min ( n = 5). Neurostimulation via the permanent lead elicited negative dromotropic effects with stimulation frequency, voltage, and impulse duration as determinants of stimulation efficacy. Conclusion Active fixation of a permanent pacing lead inside the RIGP is feasible without thoracotomy. Thereby, ventricular rate control during AF can be achieved with stimulus voltages applied for myocardial electrostimulation.

The biomechanical environment to which cells are exposed is important to their normal growth, development, interaction, and function. Accordingly, there has been much interest in studying the role of biomechanical forces in cell biology and pathophysiology. This has led to the introduction and even commercialization of many experimental devices. Many of the early devices were limited by the heterogeneity of deformation of cells cultivated in different locations of the culture plate membranes and were also attached with complicated technical/electronic efforts resulting in a restriction of the reproducibility of these devices. The objective of this study was to design and build a simple device to allow the application of dose-dependent homogeneous equibiaxial static stretch to cells cultured on flexible silicone membranes to investigate biological and biomedical questions. In addition, cultured neonatal rat atrial cardiomyocytes were stretched with the proposed device with different strain gradients. For the first time with this study we could demonstrate that stretch up to 21% caused dose-dependent changes in biological markers such as the calcineurin activity, modulatory calcineurin-interacting protein-1, voltage-gated potassium channel isoform 4.2, and voltage-gated K+channel-interacting proteins-2 gene expression and transient outward potassium current densities but not the protein-to-DNA ratio and atrial natriuretic peptide mRNA. With both markers mentioned last, dose-dependent stretch alterations could only be achieved with stretch up to 13%. The simple and low-cost device presented here might be applied to a wide range of experimental settings in different fields of research.

This study was designed to develop a technique to selectively increase the sympathetic tone to the heart by cardiac sympathetic nerve stimulation (SNS).Access to the cardiac sympathetic neurons may allow modulating the adrenergic tone of the heart while avoiding systemic side effects.Cardiac sympathetic nerves course within neural sleeves along the subclavian artery. Because of this proximity, transvascular SNS was attempted with electrode catheters inside the subclavian artery in 16 pigs.Right/left (R-/L-) SNS (20 Hz) during ventricular pacing at 200/min evoked a100% increase of left ventricular systolic pressure (baseline: 51 +/- 1 mm Hg; L-SNS: 118 +/- 26 mm Hg; R-SNS: 116 +/- 33 mm Hg; p0.001) while systemic vascular resistance remained unchanged. There was a sigmoid dose-response curve with rapid on- and offset of the effect during SNS initiation/cessation. Positive inotropic effects persisted for 12 h of continued SNS (n = 4). Besides positive dromotropic effects, L-SNS/R-SNS yielded a 41% and 77% sinus rate increase, respectively.The neural adrenergic tone to the heart can be selectively increased by catheter stimulation of cardiac efferent sympathetic nerves.

Background —The defibrillation threshold (DFT) may be affected by biphasic shock duration (BSD), electrode configuration, and capacitance. The upper limit of vulnerability (ULV) may be used to estimate the DFT. For different lead configurations and phase 2 capacitances, we investigated in 18 pigs whether the use of ULV may predict waveforms with lowest DFT. Methods and Results —DFT and ULV were determined by up-down protocols for 10 BSDs. ULVs were measured by T-wave scanning during ventricular pacing (cycle length 500 ms). In protocol 1 (n=6), a pectoral “active can” was combined with an electrode in the superior vena cava as common cathode and a right ventricle electrode as anode (AC+SVC). In protocol 2 and protocol 3 (n=6 each), only the “active can” was used as proximal electrode (AC). Capacitance was 150 μF during both phases in protocol 1 and protocol 3 but 150 μF (phase 1) and 300 μF (phase 2) in protocol 2. ULV and DFT demonstrated a linear correlation in each protocol ( r =0.78 to 0.84). Lowest DFTs were found at 10 ms for AC+SVC and at 14 ms for AC ( P P =0.04). Conclusions —The BSD with lowest DFT is shorter for AC+SVC than for AC. There is no significant difference in voltage DFT between both at optimal BSD. A lower phase 2 capacitance reduces DFTs irrespective of BSD. Because strength-duration curves for DFT and ULV correlate for different BSDs, lead systems, and phase 2 capacitances, ULV determination may allow the prediction of waveforms with lowest DFT.

To the Editor: Atrial thrombus exclusion by transesophageal echocardiography (TEE) prior to cardioversion (CV) of atrial fibrillation (AF) shortens the time to CV and reduces hemorrhagic complications compared to a three- to four-week period of oral anticoagulation before CV ([1][1]). Because of the