Atrial fibrillation: mortality, morbidity, and money; is that all? Importance and variability of burden measurement.
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Atrial Fibrillation↗
Biomedical subjects
Thorsten Lewalter
Publications and source records attributed to Thorsten Lewalter.
Defective epidermal barrier in neonatal mice lacking the C-terminal region of connexin43.
More than 97% of mice in which the C-terminal region of connexin43 (Cx43) was removed (designated as Cx43K258stop) die shortly after birth due to a defect of the epidermal barrier. The abnormal expression of Cx43K258stop protein in the uppermost layers of the epidermis seems to perturb terminal differentiation of keratinocytes. In contrast to Cx43-deficient mice, neonatal Cx43K258stop hearts show no lethal obstruction of the right ventricular outflow tract, but signs of dilatation. Electrocardiographies of neonatal hearts reveal repolarization abnormalities in 20% of homozygous Cx43K258stop animals. The very rare adult Cx43K258stop mice show a compensation of the epidermal barrier defect but persisting impairment of cardiac function in echocardiography. Female Cx43K258stop mice are infertile due to impaired folliculogenesis. Our results indicate that the C-terminally truncated Cx43K258stop mice lack essential functions of Cx43, although the truncated Cx43 protein can form open gap junctional channels.
Animals↗
Incidence of venous obstruction following insertion of an implantable cardioverter defibrillator. A study of systematic contrast venography on patients presenting for their first elective ICD generator replacement.
AIMS: The number of implantable cardioverter defibrillator (ICD) implantations, as well as follow-up procedures such as generator exchanges, lead revisions and lead system upgrades, is ever-increasing. Lead revisions and implantation of additional leads require venous access at the site of the previous ICD implantation. The aim of our study was therefore to evaluate the incidence of venous obstruction after chronic transvenous ICD system implantation. METHODS AND RESULTS: One hundred and five consecutive patients admitted for their first elective ICD generator replacement were included. All patients underwent bilateral contrast venography and the images were analyzed by two attending radiologists. Venous obstruction was classified as moderate stenosis (50-75% diameter reduction), severe stenosis (>75%) or total occlusion. Venous obstruction of various degrees was found in 25% of the patients. Complete occlusion was found in 9%, severe stenosis in 6% and moderate stenosis in 10% of the patients. The incidence of venous obstruction was increased in patients with a pacemaker prior to the initial ICD system implantation (67%). No difference was found in patients with a single defibrillator lead compared with patients who had an additional superior vena cava (SVC) shocking coil. However, the presence of a second shocking coil in the SVC incorporated in a single ICD lead was associated with an increased incidence of venous obstruction. No difference was found between silicone and polyurethane insulated leads. CONCLUSION: This study shows that venous obstruction occurs relatively frequently after ICD implantation. Therefore, contrast venography should always be obtained if malfunction of a preexistent lead is suspected or a system upgrade is considered.
Brachiocephalic Veins↗
ECG signs mimicking acute inferior wall myocardial infarction are associated with elevated myocardial enzymes during isolation of pulmonary vein for focal atrial fibrillation.
In this study, we report an intraprocedural incident in patients undergoing ablation for atrial fibrillation. During left atrial manipulation our patients suffered from acute chest pain, showed ECG signs of an acute inferior wall myocardial infarction, and increased levels of cardiac Troponin I (cTnI). We strongly recommend being aware of unexpected reactions during isolating pulmonary veins for focal atrial fibrillation, especially when passing the dorsal part of the left atrium. If pericardial effusion is ruled out and ECG signs as well as symptoms disappear, the ablation procedure should proceed. We think patients undergoing pulmonary vein ablation for atrial fibrillation should be informed of this threatening complication.
Adult↗
Characterization of a new pulmonary vein variant using magnetic resonance angiography: incidence, imaging, and interventional implications of the "right top pulmonary vein".
INTRODUCTION: Catheter ablation of the pulmonary veins (PVs) for prevention of recurrent atrial fibrillation requires precise anatomic information. We describe the characteristics of a new anatomic variant of PV anatomy using magnetic resonance angiography. METHODS AND RESULTS: A 1.5-T magnetic resonance imaging system with a body coil or a torso phased-array coil was used before and after gadolinium injection. Magnetic resonance angiograms were acquired with a breath-hold three-dimensional fast spoiled gradient-echo imaging sequence in the coronal plane. Three-dimensional reconstruction with maximum intensity projections and multiplanar reformations was performed. A newly described variant PV ascending from the roof of the left atrium was found in 3 of 91 subjects. The mean ostial diameter of the roof PV was 7 +/- 2 mm, the mean distance from the ostium to the first branching point was 22 +/- 8.5 mm, and the mean distance to the right superior PV was 3.3 +/- 0.6 mm. CONCLUSION: We refer to the newly described variant of PV anatomy as the "right top pulmonary vein." It is important to be aware of this anatomic pattern to avoid inadvertent catheter intubation, which can result in misleading mapping results and PV stenosis.
Adult↗
Influence of basic heart rate and sex on heart rate turbulence in healthy subjects.
Acceleration and deceleration of the heart rate after the occurrence of a ventricular premature complex is characterized as heart rate turbulence (HRT). Two parameters quantify heart rate turbulence: onset and slope. The physiological properties have not been clarified in a large cohort of persons yet. This study evaluated properties of HRT, and focused on the influence of basic heart rate and sex on HRT. Using a special protocol, 95 persons were studied prospectively. HRT and its physiological properties were determined in 95 persons using Holter ECGs. The authors found 24% with a turbulence onset 0% and 5% with a turbulence slope <2.5 ms/RRI. Mean heart rate during Holter differed significantly between women and men (745 vs 817 ms, P < 0.0001). A linear, weighted regression model revealed that an increased heart rate before a ventricular premature complex is associated with a decreased turbulence onset (P < 0.0001). Turbulence slope was attenuated by basic heart rate only in men (P = 0.0022). On the contrary, the study detected no influence of the basic heart rate on turbulence slope in women (P = 0.0015 for the comparison between women and men). Basic heart rate and sex show an influence on HRT and should be considered when using HRT for noninvasive risk stratification.
Adult↗
Influence of the point of origin on heart rate turbulence after stimulated ventricular and atrial premature beats.
BACKGROUND: Heart rate turbulence (HRT) is a new and auspicious parameter for risk stratification in patients suffering from structural heart disease. The HRT parameters onset (TO) and slope (TS) are derived from Holter ECGs. Only a few studies have evaluated physiologic properties like age or prematurity of the ventricular beat on HRT. Until now, to our knowledge, little is known about the influence of the point of origin of the premature beat on HRT. Therefore, we conducted a study consisting of 25 patients (pts) with premature beats generating from 2 different sites in the atrium and ventricle. METHODS: During an electrophysiologic study, premature extra beats were induced. The high right atrium (HRA) and the lateral part of the coronary sinus (CS) represented the atrial pacing sites, while the right ventricular apex (RVAP) and right ventricular out flow tract (RVOT) represented the ventricular pacing sites. Prematurity started at 450 ms and was decreased to the refractoriness of each site. TO and TS were computed and correlated to the site of origin and the coupling interval (CI). RESULTS: Atrial TO was positive in 9 pts (HRA) and 7 (CS) as well as ventricular TO in 2 pts, respectively. TO induced in CS correlated with the CI (r = -0.50, p < 0.05). TS was negative, independent of the site of origin. Atrial TS showed no correlation with the CI. TO generated from both ventricular sites was positive in 2 pts. TO from RVAP correlated with the CI (r = -0.81, p < 0.005), but not with RVOT. TS from both ventricular sites exhibited no correlation with the pacing site, but correlated with themselves (r = -0.69, p < 0.03). CONCLUSION: The site of origin of the premature beat exhibits no influence on heart rate turbulence slope. The prematurity of the extra beat correlates with turbulence onset, but not with slope. Finally, the site of origin revealed no influence on HRT slope. Therefore, the calculation of heart rate turbulence derived from extra beats extracted from Holter ECG is reliable.
Atrial Premature Complexes↗
Decremental pulmonary venous pulse propagation: impact for catheter ablation in focal atrial fibrillation.
BACKGROUND: Electrical isolation of pulmonary veins (PV's) is crucial to achieve success in catheter ablation for trigger elimination in focal atrial fibrillation (AF). To guide ostial PV radiofrequency (RF) delivery, it is necessary to identify the electrical breakthrough (EBT) between PV and left atrium. For this purpose, coronary sinus (CS) fixed rate pacing is commonly used. This study evaluated, whether CS extrastimulus pacing is superior in identifying the EBT area as compared to fixed rate pacing. METHODS: In 9 patients (51 +/- 10 years) undergoing a left sided electrophysiological study for AF ablation, 25 PV's (10 right and 15 left-sided PV's) were mapped using a 4 French fixed-wire catheter with eight 6 mm coiled Platinum electrodes in a distal looped configuration (Revelation Helix, Cardima Inc.). For mapping and ablation the electrode loop was positioned in the PV ostium rectangular to the longitudinal PV axis. EBT area was identified as those electrodes indicating the earliest PV signals during CS pacing. We measured number of EBT electrodes and time between EBT and the latest activated bipoles at the electrode loop during fixed rate and extrastimulus pacing. The reduction of two or more EBT electrodes was defined as a significant benefit in EBT identification. RESULTS: In 22 of 25 PV's mapped PV potentials could be observed. Performing fixed rate pacing the EBT area was identified in a mean of 4.2 +/- 1 electrodes, whereas using extrastimulus pacing, EBT area could be significantly reduced to 2.3 +/- 0.8 electrodes. The time between EBT and latest electrode activated increased from 14 +/- 7 ms to 22 +/- 10 ms indicating an intrapulmonary conduction delay during extrastimulus pacing. In 13 of 22 PV's mapped (59%), extrastimulus pacing was beneficial in the identification of the EBT, as the primary target for RF delivery. CONCLUSIONS: CS extrastimulus pacing induces intra-PV decremental conduction properties allowing one to identify a more localised and smaller EBT area as the primary target for RF delivery. Performing PV ablation to treat focal AF, extrastimulus maneuvers allow to unmask the "true" EBT and thus may help to limit intrapulmonary RF delivery.
Adult↗
Advanced pacemaker diagnostic features in the characterization of atrial fibrillation: impact on preventive pacing algorithms.
Pacing algorithms to prevent PAF are mainly based on the suppression of premature atrial complexes (PACs), which play an important role in its initiation. In contrast to 24-hour ambulatory electrocardiograms, advanced pacemaker (PM) diagnostic features are capable of recording AF episodes during long follow-up periods and of characterizing AF in a detailed fashion. For the specific use of these algorithms, a detailed characterization of AF was performed in 91 dual chamber PM recipients with histories of AF. Fifteen patients with episodes of oversensing due to far-field signals or frequent episodes of "2:1-undersensing" of atrial flutter were excluded. The remaining 76 patients had high recurrence rates of AF (median 0.8 episodes/day), however, the majority of episodes lasted < 7 minutes. Despite frequent PACs (median 10.8/hour) during sinus rhythm, a median of 66.4% of the AF episodes were preceded by < 2 PACs/min before onset. In conclusion, frequent, short-lived AF episodes seem best suited for AF preventive pacing therapies. However, the small number of PACs preceding many AF episodes may limit the efficacy of PAC suppressing algorithms.
Algorithms↗
Accessory pathway catheter ablation inside the neck of a coronary sinus diverticulum.
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Atrioventricular Node↗
Increasing myocardial contraction and blood pressure in C57BL/6 mice during early postnatal development.
Knowledge of the developmental changes of cardiovascular parameters in the genetic background of a mouse strain is important for understanding phenotypic changes in transgenic or knockout mouse models for heart disease. We studied arterial blood pressure and myocardial contractility in mice of the common background strain C57BL/6, aged 21 days [postnatal day 21 (P21)] to 580 days. Heart rate increased during maturation from 396 beats/min at P21 to 551 beats/min at postnatal day 50 (P50), and mean arterial blood pressure increased in parallel from 86 to 110 mmHg and remained constant afterward. Echocardiographically determined left ventricular myocardial wall dimensions (R = 0.79, P < 0.0001) and left ventricular mass calculated using the area-length algorithm correlated strongly with histomorphometrical measurements (R = 0.93, P < 0.001). Sarcomere shortening records from isolated ventricular myocytes used as a measure for myocardial contractility revealed a negative shortening-frequency relation under a pacing frequency of 2 Hz and a positive relation above 2 Hz. Shortening amplitudes recorded from P21 myocytes were smaller, and the shortening-frequency relation was less steep than in adult myocytes. A stimulation pause was followed by a negative "staircase" at pacing frequency of < or =6 Hz and a positive staircase at > or =6 Hz. P21 myocytes developed positive staircases at 8 and 10 Hz, and adult myocytes also developed them at 6 Hz. Blood pressure increase during maturation until P50 may originate from increasing single cardiomyocyte contractility.
Aging↗
Long-term follow-up of fast pathway radiofrequency ablation in atrioventricular nodal reentrant tachycardia.
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Atrioventricular Node↗
[Atrial fibrillation: stimulation and pacemaker therapy].
UNLABELLED: Pacing therapy is well established in all cases of symptomatic bradyarrhythmic atrial fibrillation. In paroxysmal or persistent atrial fibrillation, the implanted dual chamber pacemaker device should incorporate an automatic mode switching algorithm. Mode switch in case of atrial fibrillation detection avoids pacemaker mediated rapid ventricular pacing during an atrial tachyarrhythmia and allows to perform dual chamber pacing during phases of sinus rhythm which is the preferable mode due to improved hemodynamics, rate adaptation, lower progress in atrial fibrillation burden and a lower rate of thromboembolic events as compared to ventricular pacing. PERSPECTIVE: The possibility to prevent from atrial fibrillation recurrencies by pacing is currently under investigation. Various methodological approaches, for example multisite or alternate single site pacing, preventive pacing algorithms or hybrid- and even triple-therapy concepts are used for that purpose. Due to the theoretical point of view, that all these pacing interventions may reduce atrial fibrillation but also have the potential to act in a proarrhythmic manner, the data from adequately designed trials is of major importance: Septal pacing and preventive pacing algorithms seem to have a beneficial effect in a limited number of so far available studies. CONCLUSION: In clinical practice, preventive pacing and/or placement of the atrial lead in a septal position should therefore be available in those patients with a conventional pacing indication in addition to symptomatic recurrent atrial fibrillation. Preventive pacing is so far with a significant and not-predictable amount of non-responders no "early" stage of therapy in patients with recurrent symptomatic atrial fibrillation and no additional conventional pacing indication.
Algorithms↗
Induction of atrial fibrillation in mice by rapid transesophageal atrial pacing.
OBJECTIVE: Atrial fibrillation (AF) as an "indicator arrhythmia" for enhanced atrial vulnerability in mouse hearts has not yet been systematically examined. We therefore evaluated a transesophageal rapid atrial stimulation protocol for the induction of AF in C57Bl/6 mice. METHODS: 40 C57Bl/6 mice (19 female and 21 male; 5.2 +/- 2.1 months; 18 - 27 g) were examined by closed chest transesophageal atrial stimulation. Baseline ECG and electrophysiological parameters, AF-inducing stimulation cycle length (CL) and AF duration were analyzed. RESULTS: The surface ECG demonstrated a significantly faster heart rate in female mice (R-R: 138.7 +/- 19.9 ms versus 150.5 +/- 15.7 ms, P < 0.05). AF was inducible in 90 % of the population and not inducible in 4 mice, all female (21 % in this subgroup). Mean induction CL was 27.4 +/- 7.3 ms. Mean AF duration was 26.9 +/- 42.6 s before spontaneous termination. In a subgroup of 4 female and 4 male mice (mean age 7.5 months), successive testing of AF induction showed a range of higher susceptibility to AF at stimulus amplitudes of 3.0 - 4.0 mA and stimulation CLs between 15 - 25 ms. AF induction was observed to be constantly reproducible in the individual animals. No correlation to pacing stimulus length and amplitude was found. CONCLUSIONS: This study demonstrates that it is possible to reproducibly induce self-terminating AF and supraventricular arrhythmias in mice by transesophageal atrial burst stimulation. The presented method allowing serial testings of the same animal can be a useful tool in further investigations with transgenic mice and might be helpful in the characterization of underlying genetic or molecular mechanisms of AF.
Animals↗
Circumferential pulmonary vein mapping and ablation in focal atrial fibrillation: single catheter technique.
BACKGROUND: Atrial fibrillation (AF) can be cured in a subgroup of patients performing catheter ablation and eliminate trigger arrhythmias mainly originating in the pulmonary veins (PV's). CASE REPORT: This case report describes the use of a novel catheter design combining both, circumferential mapping and radiofrequency delivery capabilities to perform pulmonary vein ablation in patients with focal AF. It could be demonstrated that this catheter was able to eliminate pulmonary vein potentials in a single left atrial catheter technique without acute evidence for PV stenosis. In two PV's of a second patient, where the Helix catheter was placed in a very ostial position, it was not possible to completely eliminate the PV signal component of the ostial electrogram. Long-term follow-up with AF recurrence documentation will clarify whether ostial PV signal amplitude reduction may serve as an acceptable procedural endpoint. CONCLUSION: PV potential elimination is feasible using this novel catheter design; safety and long-term efficacy of this single catheter approach will be evaluated in a multicenter study (BITMAP study: Breakthrough and Isolation Trial: Mapping and Ablation of Pulmonary Veins).
Adult↗
Radiofrequency catheter ablation of an incessant ventricular tachycardia following valve surgery.
Sustained monomorphic ventricular tachycardia (VT) after valve surgery represents a clinical entity with different tachycardia mechanisms. This case report describes an incessant VT after tricuspid and aortic valve replacement that did not respond to antiarrhythmic drug treatment. The tachycardia exhibited VA block and a right bundle branch block pattern with left-axis deviation, suggesting ventricular excitation via the left posterior fascicle. The electrophysiological study was limited by the prosthetic tricuspid and aortic valve replacement, therefore a transseptal approach was necessary to obtain access to the ventricular myocardium. Radiofrequency catheter ablation was performed in the proximal left bundle or distal His region with termination of the incessant VT followed by complete AV block. After pacemaker implantation using a transvenous right atrial and an epicardial ventricular lead, no VT reoccurrence could be documented.
Aortic Valve↗