bluuebunny/crossref_metadata_2025 huggingface dataset:
Germline hMLH1 promoter mutation in a Newfoundland HNPCC kindred
Authors: Green RC , Green AG , Simms M , Pater A , Robb JD , Green JS
Published: August 2003

Hereditary non‐polyposis colon cancer (HNPCC) is an autosomal dominant form of inherited predisposition to colorectal and other malignancies. It is associated with mutations in DNA mismatch‐repair genes, especially hMSH2 and hMLH1. Management of HNPCC families is improved if the underlying mutation in each family can be discovered. We describe a Newfoundland kindred, meeting the Amsterdam Criteria for HNPCC, in which a mutation in the promoter region of the hMLH1 gene co‐segregates with the disease phenotype. The −42C > T mutation is within a putative Myb proto‐oncogene binding site. Using electrophoretic mobility shift assays, we demonstrated that the mutated Myb binding sequence is less effective in binding nuclear proteins than the wild‐type promoter sequence. Using in vivo transfection experiments in HeLa cells, we further demonstrated that the mutated promoter has only 37% of the activity of the wild‐type promoter in driving the expression of a reporter gene. The average age of onset in six family members affected with colorectal cancer is 62 years, which is substantially later than the typical age of onset in HNPCC families. This is consistent with a substantial decrease, but not total elimination, of mismatch repair function in affected members of this family. This is the first report of a heritable hMLH1 promoter mutation in any HNPCC family.
Food protein‐induced enterocolitis syndrome – not only due to cow's milk and soy
Authors: Levy Yael , Danon Yehuda L.
Published: August 2003

Over a of 7‐year period, six patients (four males, two females aged 3–12 months) were diagnosed with food protein‐induced enterocolitis syndrome (FPIES) triggered by foods other than cow's milk and soy: chicken in four, turkey in two, peas in one, and lentils in one (five patients reacted to more than one food type). All reactions developed within 2 h of ingestion of the allergenic food. To exclude other conditions with similar clinical symptoms, three infants underwent work‐up for sepsis, one infant underwent work‐up to exclude metabolic defects, and one underwent a barium enema to rule out intussusception. All were negative. Pediatricians should be aware that FPIES may be caused by foods other than cow's milk and soy, mainly chicken, turkey and foods from the legume family, and that it may present also in infants older than 6 months.
Movements of Atlantic salmon migrating upstream through a fish‐pass complex in Scotland
Authors: Gowans A. R. D. , Armstrong J. D. , Priede I. G. , Mckelvey S.
Published: August 2003

Abstract  – Movements of adult Atlantic salmon were tracked through a series of four fish passes and an impoundment on the River Conon system, Northern Scotland. Proportions of fish passing individual obstructions ranged from 63 to 100%. The cumulative effect was that only 4 of the 54 tagged fish reached the spawning areas. The fish were delayed for 1–41 days at a pool‐and‐overfall ladder and 1–52 days at a Borland fish lift. The fish swam through a 10 km long reservoir at 0.21–1.16 km·h−1. A total of 13 fish negotiated a 2.5 km long, 3 m diameter diversion tunnel through a mountain to their home river. High levels of electromyogram (EMG) activity were recorded during ascent of a pool‐and‐overfall fish ladder, indicating that high energy demanding burst swimming was required.
Toxoplasma gondii: Perfecting an Intracellular Life Style
Authors: Sibley L. David
Published: August 2003

Toxoplasma gondii is a widespread protozoan parasite that infects all nucleated cell types of warm‐blooded vertebrates. Parasite motility is regulated by polymerization of new actin filaments that provide a substrate for the small myosin TgMyoA. Interaction between the cytoplasmic tails of parasite adhesins and the actin‐binding protein aldolase links these cell surface proteins with the cytoskeleton. Translocation of adhesins coupled to extracellular receptors allows the parasite to glide across the substrate. This conserved system is important for active penetration into host cells and tissue migration by T. gondii. Entry into the host cell is accompanied by dramatic remodeling of the intracellular vacuole that the parasite resides in. This compartment resists fusion with host cell endocytic organelles, yet recruits mitochondria and endoplasmic reticulum in order to gain access to host cell nutrients. The combined abilities to actively penetrate host cells and control the fate of the parasite‐containing vacuole contributes to the remarkable success of T. gondii as an intracellular parasite.
Mycobacterium tuberculosis Phagosome Maturation Arrest: Selective Targeting of PI3P‐Dependent Membrane Trafficking
Authors: Vergne Isabelle , Chua Jennifer , Deretic Vojo
Published: August 2003

The ability of Mycobacterium tuberculosis to enter host macrophages, and reside in a phagosome, which does not mature into a phagolysosome, is central to the spread of tuberculosis and the associated pandemic involving billions of people worldwide. Tuberculosis can be viewed as a disease with a significant intracellular trafficking and organellar biogenesis component. Current understanding of the block in M. tuberculosis phagosome maturation also sheds light on fundamental aspects of phagolysosome biogenesis. The maturation block involves interference with the recruitment and function of rabs, rab effectors (phosphatidylinositol 3‐kinases and tethering molecules such as EEA1), SNAREs (Syntaxin 6 and cellubrevin) and Ca2+/calmodulin signaling. M. tuberculosis analogs of mammalian phosphatidylinositols interfere with these systems and associated processes.
Regulation of EGF‐Induced Phospholipase C‐γ1 Translocation and Activation by its SH2 and PH Domains
Authors: Wang Yi , Wang Zhixiang
Published: August 2003

Translocation of phospholipase C‐γ1 is essential for its function in response to growth factors. However, in spite of recent progress, the phospholipase C‐γ1 translocation pattern and the molecular mechanism of the translocation are far from fully understood. Contradictory results were reported as to which domain, PH or SH2, controls the epidermal growth factor‐induced translocation of phospholipase C‐γ1. In this communication, we studied epidermal growth factor‐induced translocation of phospholipase C‐γ1 by using comprehensive approaches including biochemistry, indirect fluorescence and live fluorescence imaging. We provided original evidence demonstrating that: (i) endogenous phospholipase C‐γ1, similar to YFP‐tagged phospholipase C‐γ1, translocated to endosomes following its initial translocation from cytosol to the plasma membrane in response to epidermal growth factor; (ii) phospholipase C‐γ1 remained phosphorylated in endosomes, but phospholipase C‐γ1 activity is not required for its translocation, which suggests a signaling role for phospholipase C‐γ1 in endosomes; (iii) the PH domain was not required for the initial translocation of phospholipase C‐γ1 from cytosol to the plasma membrane, but it stabilizes phospholipase C‐γ1 in the membrane at a later time; (iv) the function of the phospholipase C‐γ1 PH domain in stabilizing phospholipase C‐γ1 membrane association is very important in maintaining the activity of phospholipase C‐γ1; and (v) the role of the PH domain in phospholipase C‐γ1 membrane association and activation is dependent on PI3K activity. We conclude that the phospholipase C‐γ1 SH2 and PH domains coordinate to determine epidermal growth factor‐induced translocation and activation of phospholipase C‐γ1.
Exploring views on Swedish district nurses' prescribing – a focus group study in primary health care
Authors: Wilhelmsson Susan , Foldevi Mats
Published: August 2003

• Since 1994 district nurses (DNs) in Sweden have been permitted to prescribe drugs from a limited list. This reform has met severe resistance from doctors and the opinions of general practitioners (GPs) and DNs have differed in many aspects.

• The aim of this study was to gain deeper understanding of the different opinions about DNs' prescribing and to explore the impact of the reform on primary care.

• Six focus group interviews were conducted, four with DNs and two with GPs.

• Data analysis revealed six categories, which were condensed into two dimensions. The dimensions were individual prerequisites, with the categories responsibility and knowledge, and organizational prerequisites, with the categories distribution of work, climate of co‐operation, resistance and economic considerations.

• District nurses were very positive towards prescribing and had gained new knowledge through the compulsory training course and via discussions with pharmacists. Because of the responsibility required for prescribing, some nurses had introduced systems for self‐monitoring. Prescribing was seen as a natural part of the nursing process. All interviewees could describe periods of resistance against the reform, and the head of the health centre was a key person for attitudes at the workplace.

• The DNs found the nurse prescribing reform very positive. They experienced a strengthening of professionalism and also thought that the reform was a natural development. Negative attitudes and opinions offset the positive feelings. The resistance that had appeared in the beginning had now turned into silent acceptance.
Seeing the person behind the patient: enhancing the care of older people using a biographical approach
Authors: Clarke Amanda , Jane Hanson Elizabeth , Ross Helen
Published: August 2003

• Recent policy statements have stressed the need for fundamental changes to the NHS, especially to the hospital care of older people. Person‐centred care underpins such changes. If practitioners are to deliver person‐centred care, then they need to learn more about the patient as an individual. One way that this might be achieved is through biographical approaches.

• This paper describes the findings of a developmental study undertaken over a 6‐month period to investigate the introduction of a biographical approach to care on a unit in a NHS hospital. It concentrates on the views of the practitioners who used the approach.

• The study aimed to explore whether a biographical approach – in the form of storytelling – might be used to encourage person‐centred practice.

• Using a practice development approach, the study explored the views of older people, their family carers and practitioners regarding their participation in life story work.

• Initial data were collected by focus groups with staff from a nursing home who regularly used life stories as a basis for care planning. Further data were collected through focus groups, semistructured interviews and observation – undertaken before and after the introduction of life story work – with older people, family carers and practitioners.

• Findings revealed that life stories helped practitioners to see patients as people, to understand individuals more fully and to form closer relationships with their families. Support workers also said how much they enjoyed using the approach to inform their care.

• Further longitudinal research is required to investigate biographical approaches more fully and to work more closely with practitioners to explore how biographical approaches can be undertaken as part of standard practice and be integrated into the culture and management of care.
Nurse practitioner–client interaction as resource exchange in a women's health clinic: an exploratory study
Authors: Donohue Rebecca K.
Published: August 2003

• Empirical research has thoroughly documented the success of nurse practitioners (NPs) in terms of patient satisfaction and cost‐effectiveness. What is missing is the in‐depth knowledge of the interactive process through which this is accomplished during a clinic visit.

• The aim of this study was to understand the special nature and processes of NP and client encounters in the ambulatory primary care context using a resource exchange perspective.

• An exploratory descriptive design was used to address the following research questions: (i) What do midlife female clients expect in terms of resources to be exchanged prior to a visit with a NP in an ambulatory clinic visit? (ii) What resources are actually exchanged during the clinic visit? (iii) To what extent is there congruence between a woman's expectations and what she is actually receiving from the clinic visit in terms of resources exchanged?

• The participants included two women health NPs and eight midlife female clients.

• Data for the study were comprised of audiotaped pre‐ and postencounter interviews with the clients, audiotapes of the entire clinic visits with the NP and field notes recorded by the researcher of the client visits. Content analysis was conducted using ETHNOGRAPH software.

• Findings indicated that clients of both NPs had surprisingly similar expectations of receipt of services as well as actual receipt of services. Resources expected and received from the visits included some combination of services, health information, trust, self‐disclosure, support, affirmation, time, acceptance and respect.

• Results of this study suggest that resource exchange theoretical formulations can be applied to NP–client interactions to understand and explain the specific nature of resources the clients expect and receive from a NP during a woman's health clinic visit.
Repression of the Ac‐transposase gene promoter by Ac transposase
Authors: Fridlender Marcelo , Harrison Kate , Jones Jonathan D.G. , Levy Avraham A.
Published: August 2003

Mobility of the maize Ac‐Ds transposable element family depends on the production of Ac‐encoded transposase (TPASE). The TPASE is a DNA‐binding protein which recognizes internal sites near both Ac termini in a region which overlaps the putative TPASE gene promoter. Therefore, it was hypothesized that TPASE may regulate its own transcription. The TPASE effect on Ac promoter activity was tested in transgenic tobacco plants and in protoplasts transformed with Ac‐promoter‐β‐glucuronidase gene fusions. It was found that TPASE can repress Ac promoter activity in cotyledons and leaves of transgenic plants, as well as in transient assays in protoplasts. TPASE‐mediated repression occurs independently of the presence of the Ac untranslated leader or of the 3′ termini. When fused to a deleted (−67) cauliflower mosaic virus 35S promoter, the first 237 bp of Ac (starting from the 5′ end) are sufficient to enable TPASE‐mediated repression. The results indicate that TPASE can act as a transcriptional repressor. The possible mechanisms and significance of TPASE‐mediated repression are discussed.
Design in Arabidopsis thaliana of a synchronous system of floral induction by one long day
Authors: Corbesier Laurent , Gadisseur Isabelle , Silvestre Georges , Jacqmard Annie , Bernier Georges
Published: August 2003

A system of one‐shot induction of flowering in Arabidopsis thaliana, ecotype Columbia, is described. Plants from vernalized seeds are grown for 2 months in 8 h short days at an irradiance of 48 µmol m−2 sec−1 (fluorescent light only). At that age they can be induced to flower by exposure to either a single long day or a single displaced short day. Non‐induced plants stay vegetative for at least a further month. Synchrony of induction among the individuals of the population exposed to one long day is of the same order as in the best classical model plants, that is, the fastest individuals are only 6 h ahead of the slowest ones. A further advantage of this system is the large size of plants at the time of induction, allowing easy analysis of changes in leaves, leaf exudate and shoot meristem. The design of such a synchronous system will allow the timings of gene activations and deactivations to be established in the different plant parts, before flowers are initiated.
Crow–Fukase (POEMS) syndrome: a study of peripheral nerve biopsy in five new cases
Authors: Vital Claude , Vital Anne , Ferrer Xavier , Viallard Jean‐François , Pellegrin Jean‐Luc , Bouillot Sandrine , Larrieu Jean‐Marc , Lequen Laurence , Larrieu Jean‐Louis , Brechenmacher Christiane , Petry Klaus G. , Lagueny Alain
Published: August 2003

Abstract  The pathogenesis of Crow–Fukase (POEMS) syndrome is not well known, and in some cases, a definite diagnosis is difficult to establish. Nerve fibers have been studied in about 120 peripheral nerve biopsies (PNBs), and a mixture of axonal and demyelinating lesions were found in most of them. We report five new cases of Crow–Fukase (POEMS) syndrome with ultrastructural examination of their PNBs. In every case, there were features of axonal degeneration and primary demyelination. Interestingly, uncompacted myelin lamellae (UMLs) were present in every case at a percentage of 1–7. The association of UML and Crow–Fukase (POEMS) syndrome was described 20 years ago but was only reported in a few studies and found in 31 of 41 cases. In fact, this association is very significant because apart from Crow–Fukase (POEMS) syndrome, UMLs can only be found with such a frequency in rare cases of Charcot–Marie–Tooth disease type 1B. UML was also reported in acute and chronic inflammatory demyelinating polyneuropathies but at a much lower percentage. Moreover, in our five cases, UML was frequently associated with a decrease in the number of intra‐axonal filaments, and this finding raises the problem of relationships between myelin formation and neurofilaments. So far, glomeruloid hemangiomas present in the dermis of some patients are considered as the only specific criteria of Crow–Fukase (POEMS) syndrome, but we think UML can also be regarded as highly suggestive of this entity on condition that a thorough ultrastructural examination of a PNB is performed.
Electroanatomic Analysis of Sinus Impulse Propagation in Normal Human Atria
Authors: DE PONTI ROBERTO , HO SIEW YEN , SALERNO‐URIARTE JORGE A. , TRITTO MASSIMO , SPADACINI GIAMMARIO
Published: August 2003

Sinus Impulse Propagation in Normal Human Atria.
Introduction: Better understanding of atrial propagation during sinus rhythm (SR) in normal hearts under the most normal physiologic conditions may be propaedeutic to pathophysiologic studies of complex atrial arrhythmias. In this study, qualitative and quantitative analyses of sinus impulse propagation in both atria were performed by electroanatomic mapping in patients with no organic heart disease who were undergoing an electrophysiologic procedure.

Methods and Results: Seven patients (5 men and 2 women; age 37 ± 11 years) undergoing ablation of a left‐sided accessory pathway were considered. Associated heart disease and coexisting atrial arrhythmias were excluded. After obtaining informed consent, electroanatomic mapping of both atria was performed during SR using a nonfluoroscopic system in the postablation phase. Mapping was accomplished in all patients with no complications. Qualitative analysis showed that sinus impulse propagation gives a reproducible activation pattern with minor individual variations. During interatrial propagation, two breakthroughs (anterior and posterior) in the left atrium are observed in the majority of cases. The anterior breakthrough, which reflects conduction over Bachmann's bundle, is predominant and shows a peculiar “preexcitation‐like” endocardial activation pattern. Quantitative analysis showed minimal individual variations of propagation time intervals. Atria are activated simultaneously for 65% ± 9% of the duration of the atrial systolic time interval.

Conclusion: In normal humans, electroanatomic mapping of SR identifies a typical and reproducible propagation pattern during SR. Bachmann's bundle plays the most important role in interatrial propagation. Atria are activated simultaneously by sinus impulse for a relevant portion of the systolic time interval.
Pulmonary Vein Isolation: Comparison of Bipolar and Unipolar Electrograms at Successful and Unsuccessful Ostial Ablation Sites
Authors: TADA HIROSHI , ORAL HAKAN , WASMER KRISTINA , GREENSTEIN RADMIRA , PELOSI FRANK , KNIGHT BRADLEY P. , STRICKBERGER S. ADAM , MORADY FRED
Published: August 2003

Electrogram Analysis.
Introduction: No prior studies have quantitatively analyzed the characteristics of bipolar or unipolar electrograms that may be helpful in identifying successful ostial ablation sites in patients with atrial fibrillation undergoing segmental pulmonary vein isolation.

Methods and Results: The characteristics of bipolar and unipolar electrograms recorded at 185 successful and 120 unsuccessful ostial pulmonary venous ablation sites were analyzed in 21 patients with atrial fibrillation. A decapolar Lasso catheter was positioned near the ostia of the pulmonary veins, and a conventional ablation catheter was used to deliver radiofrequency energy at individual ostial sites where pulmonary vein potentials were recorded. With both bipolar and unipolar recordings, the only timing parameter that distinguished successful from unsuccessful ostial ablation sites was the timing of the electrogram recorded by the ablation catheter relative to the earliest pulmonary vein potential recorded by the Lasso catheter. With both bipolar and unipolar recordings, electrograms demonstrated a larger amplitude at successful than at unsuccessful ablation sites. Unipolar electrograms had a steeper intrinsic deflection at successful than at unsuccessful ostial ablation sites. The morphologies of the unipolar electrograms recorded by the ablation catheter and by the contiguous electrode of the Lasso catheter usually were identical.

Conclusion: In patients undergoing segmental isolation of the pulmonary veins, unipolar recordings provide more information than bipolar recordings helpful in distinguishing successful from unsuccessful ostial ablation sites. Furthermore, unipolar recordings, but not bipolar recordings, allow accurate localization of the position of the ablation catheter relative to the electrodes of the Lasso catheter.
Accelerated Inactivation of Voltage‐Dependent K+ Outward Current in Cardiomyocytes from Thyroid Hormone Receptor α1‐Deficient Mice
Authors: JOHANSSON CATARINA , KOOPMANN ROLF , VENNSTRÖM BJÖRN , BENNDORF KLAUS
Published: August 2003

Voltage‐Dependent K+ Outward Current in TRα1‐Deficient Mice.
Introduction: Thyroid hormone affects the electrophysiologic properties of the heart. It is not known which of the different subtypes of thyroid hormone receptors mediate these effects.

Methods and Results: Using standard patch‐clamp techniques, we studied time‐ and voltage‐dependent properties of depolarization‐activated K+ currents in ventricular heart cells isolated from mice lacking the thyroid hormone receptor α1 (TRα1) and compared these currents with those in respective wild‐type cells. In both groups of cells, the time course of current decay could be described by two inactivating exponential components and a sustained current component. In TRα1‐deficient cells, the total inactivation time course was accelerated due to both increase of the relative contribution of the fast component and shortening of the slow time constant. The peak amplitude of the total current was not altered. The main component of steady‐state inactivation of the voltage‐dependent K+ outward current was shifted to more hyperpolarized voltages by 7 mV in TRα1‐deficient cells compared with that in wild‐type cells. Under current‐clamp conditions, action potential duration at 90% repolarization was prolonged in TRα1‐deficient cells compared with that in wild‐type cells by 3.6 msec.

Conclusion: The resulting acceleration of the total inactivation time course is proposed to contribute to action potential prolongation and thus to the increased QTend‐time observed previously on ECG of TRα1‐deficient mice.
Focal Atrial Tachycardia Originating from the Musculature of the Coronary Sinus
Authors: VOLKMER MARIUS , ANTZ MATTHIAS , HEBE JOACHIM , KUCK KARL‐HEINZ
Published: August 2003

Focal Atrial Tachycardia. Focal atrial tachycardias originate predominantly from the right atrium along the crista terminalis and less commonly from the left atrium. Successful catheter ablation usually can be performed via an endocardial approach. We report the case of a 34‐year‐old patient in whom a focal atrial tachycardia was successfully ablated 4 cm within the coronary sinus after extensive mapping of the left atrial endocardium and coronary sinus using the three‐dimensional CARTO mapping system. Rarely, atrial tachycardia can originate from the coronary sinus musculature and require ablation inside the coronary sinus.
Novel Electrophysiologic Parameter of Dispersion of Atrial Repolarization: Comparison of Different Atrial Pacing Methods
Authors: OGAWA MASAHIRO , KUMAGAI KOICHIRO , GONDO NAOKI , MATSUMOTO NAOMICHI , SUYAMA KAZUHIRO , SAKU KEIJIRO
Published: August 2003

Novel Parameter of Dispersion of Atrial Repolarization.
Introduction: Heterogeneity of ventricular repolarization plays a major role in reentrant tachyarrhythmias in cardiac tissue. However, the role of atrial repolarization added activation time (AT) to refractoriness in atrial vulnerability has not been investigated in detail.

Methods and Results: The study population consisted of 34 patients: 18 with atrial fibrillation (AF) and 16 without AF (control group). The effective refractory periods (ERPs) in the right atrial appendage, low lateral right atrium, high right septum, and distal coronary sinus, and ATs from P wave onset to each electrogram during sinus rhythm and right atrial appendage, low lateral right atrial, high right septal, distal coronary sinus, and biatrial pacing were measured. Atrial recovery time, defined as the sum of AT and ERP, and its dispersions during sinus rhythm, right atrial appendage, low lateral right atrial, high right septal, distal coronary sinus, and biatrial pacing were calculated. Both ERP dispersion and atrial recovery time dispersion during sinus rhythm were significantly greater in the AF group than in the control group. Atrial recovery time dispersion during distal coronary sinus, high right septal, or biatrial pacing was significantly smaller than that during right atrial appendage or low lateral right atrial pacing in each group. In particular, atrial recovery time dispersion during distal coronary sinus pacing was the smallest of the five pacing methods in the AF group. P wave duration during biatrial or high right septal pacing was significantly shorter than during right atrial appendage, low lateral right atrial, or distal coronary sinus pacing in each group.

Conclusion: Atrial recovery time dispersion is suitable as an electrophysiologic parameter of atrial vulnerability. Distal coronary sinus pacing may prevent AF by increasing homogeneity of atrial repolarization, whereas biatrial and high right septal pacing contribute not only homogeneity of atrial repolarization but also improvement of atrial depolarization.
Sustained Monomorphic Ventricular Tachycardia Ablation from the Aortic Sinus of Valsalva
Authors: LI YI‐GANG , GRÖNEFELD GERIAN , ISRAEL CARSTEN , HOHNLOSER STEFAN H.
Published: August 2003

Ablation of Monomorphic VT from the Aortic Sinus.
Introduction: The aim of this study was to delineate the electrophysiologic mechanisms of a novel type of ventricular tachycardia (VT) originating from the aortic sinus of Valsalva.

Methods and Results: Endocardial mapping was performed in four patients with symptomatic VT originating from the aortic sinus of Valsalva. Two patients suffered from dilative cardiomyopathy; the other two patients had no structural heart disease. Five VTs could be induced and terminated by programmed ventricular stimulation. Successful ablation was performed in the noncoronary sinus of Valsalva in three VTs and in the left aortic sinus in two. Abnormal (diastolic or presystolic) potentials were recorded during sinus rhythm (mean interval from the end of QRS complex to the potential 121 ± 98 msec) and during VT (mean interval from the potential to QRS complex 64 ± 45 msec) at effective sites in the aortic sinuses of Valsalva. Concealed entrainment was demonstrated at all successful sites. VT recurred in one patient after 1 month, whereas no recurrences were observed during follow‐up of 8 ± 6 months in the other three patients.

Conclusion: Reentry constitutes one mechanism of VT originating from the aortic sinus of Valsalva. Entrainment mapping is useful to characterize the reentrant circuit of these VTs and to guide ablation.
Clinical Evaluation of a Policy of Early Repeated Internal Cardioversion for Recurrence of Atrial Fibrillation
Authors: FYNN SIMON P. , TODD DERICK M. , HOBBS W. JULIAN C. , ARMSTRONG KAREN L. , FITZPATRICK ADAM P. , GARRATT CLIFFORD J.
Published: August 2003

Early Repeated Cardioversion for AF Recurrence.
Introduction: The clinical value of cardioversion (CV) of persistent atrial fibrillation (AF) is limited by the high rate of early AF recurrence, which may be related to the persistence of atrial electrical remodeling. We examined the hypothesis that the likelihood of maintaining sinus rhythm after CV of persistent AF is significantly enhanced by a policy of early repeated CV.

Methods and Results: Fifty‐nine patients with persistent AF underwent internal CV (CV 1). Those patients cardioverted were monitored with daily transtelephonic ECG. In the event of AF recurrence, these patients were admitted rapidly for repeat CV (CV 2) and, if further recurrence occurred, a third CV (CV 3) was performed. Daily ECG monitoring was continued until 1 month of sinus rhythm was maintained or a total of three CVs were performed. Of the 59 patients undergoing CV 1, 43 were discharged in sinus rhythm and 29 subsequently had AF recurrence during monitoring. Twenty‐three of these underwent CV 2 and 11 of these underwent CV 3. Of those having repeated CVs, only 4 patients maintained sinus rhythm for 1 month (3 after CV 2 and 1 after CV 3). The remaining patients had repeated AF recurrence during the monitoring period. Mean time from AF recurrence to CV 2 was 20 ± 13 hours and from AF recurrence to CV 3 was 13 ± 7.2 hours. Atrial effective refractory periods increased from 189 ± 16 msec at CV 1 to 215 ± 18 msec at CV 3 (P < 0.05), indicating reversal of atrial electrical remodeling during this period.

Conclusion: A policy of early repeated CVs for AF recurrence has very limited clinical value despite evidence of reversal of atrial electrical remodeling. The time between AF recurrence and repeat CV may need to be reduced further if such a policy is to succeed.
Atrial Morphology in Hearts with Congenitally Corrected Transposition of the Great Arteries: Implications for the Interventionist
Authors: JUNEJA RAJNISH , ROWLAND EDWARD , HO SIEW YEN
Published: August 2003

Atrial Morphology in Congenitally Corrected Transposition.
Introduction: In view of the possible need for septal puncture to ablate left‐sided lesions and the occasional difficulty in coronary sinus (CS) cannulation, we investigated relevant anatomic features in the right atrium of hearts with congenitally corrected transposition of the great arteries (ccTGA).

Methods and Results: Nine hearts with ccTGA and an intact atrial septum and eight weight‐matched normal hearts were examined by studying the “septal” aspect of the right atrium with reference to the oval fossa (OF). The anterior margin was arbitrarily measured as the shortest distance from the OF to the superior mitral/tricuspid annulus. The posterior margin was measured from the OF to the posterior‐most edge of the right atrial “septal” surface. The total “septal” surface width was measured at the middle of the OF. The stretched OF dimensions and CS isthmus length were noted. Mann‐Whitney test was used to compare absolute and indexed dimensions, i.e.. normalized to total width. The posterior margin in hearts with ccTGA was shorter than in controls (6.3 ± 2.4 mm vs 11 ± 1.9 mm, P < 0.001; normalized margin P = 0.09). The CS isthmus also was significantly shorter (5.3 ± 2.7 mm vs 11.4 ± 2.2 mm, P < 0.001). In two hearts with ccTGA, the CS opening into the right atrium was on the same side of the eustachian valve as the inferior caval vein.

Conclusion: The shorter posterior “septal” margin in hearts with ccTGA may increase the risk of exiting the heart while performing septal puncture when pointing the needle posteriorly. The shorter CS isthmus and the abnormal location of the CS opening in some of these hearts are important when contemplating radiofrequency ablation in this area.
Importance of Right and Left Atrial Dilation and Linear Ablation for Perpetuation of Sustained Atrial Fibrillation
Authors: ZARSE MARKUS , DEHARO JEAN‐CLAUDE , MAST FRANS , ALLESSIE MAURITS A.
Published: August 2003

Separate Atrial Dilation and Ablation.
Introduction: Atrial dilation associated with increasing atrial pressure plays an apparent role in the development of atrial fibrillation (AF). We characterized a new model of separate and biatrial dilation in the Langendorff‐perfused rabbit heart. The aim of this study was to examine if sustained AF in this model (1) would be inducible by separate right atrial (RA) and left atrial (LA) dilation; (2) would be reproducibly inducible at the same pressure level; and (3) could be suppressed by RA, LA, or biatrial ablation.

Methods and Results: Intra‐atrial pressure was increased stepwise in the RA (n = 13), LA (n = 12), or both atria (n = 25) until sustained AF could be induced or a pressure of 20 cm H2O was reached. The stimulation protocol was repeated once in RA and LA dilation (n = 9) and three times in biatrial dilation (n = 7). Then, RA orifices (superior and inferior caval veins, tricuspid valve annulus, and foramen ovale) or LA orifices (pulmonary veins, mitral valve annulus, and foramen ovale) were connected by radiofrequency (RF) lesions. Sustained AF was rendered inducible in 100% of hearts with biatrial dilation, but in only 92% of hearts with RA dilation and 67% with LA dilation. Inducibility of sustained AF was reproducible. Under biatrial dilation, not RA ablation (0/10 hearts; P = NS) but LA ablation (4/11 hearts; P < 0.05) and biatrial ablation (16/21; P < 0.01) reduced the inducibility of sustained AF.

Conclusion: The inducibility of sustained AF due to increased intra‐atrial pressure differs between the RA and LA. LA and biatrial lesions, not RA RF lesions, reduce the ability to perpetuate sustained AF.
Prominent IKs in Epicardium and Endocardium Contributes to Development of Transmural Dispersion of Repolarization but Protects Against Development of Early Afterdepolarizations
Authors: BURASHNIKOV ALEXANDER , ANTZELEVITCH CHARLES
Published: August 2003

IKs Prevents EADs in Epicardium and Endocardium.
Introduction: Previous studies from our laboratory demonstrated (1) a much larger IKs and (2) inability to induce early afterdepolarization (EAD) activity in epicardial and endocardial cells versus M cells. This study tests the hypothesis that these two characteristics are interrelated.

Methods and Results: Standard and floating microelectrode techniques were used to record transmembrane activity from the canine left ventricular epicardial, M, and endocardial regions in isolated tissue slices and arterially perfused wedge preparations. The IKr blocker E‐4031 (1 to 10 μM) caused prominent prolongation of action potential duration (APD) and induced EADs in tissues isolated from the M region, but not those from epicardium or endocardium, causing a large transmural dispersion of APD. In contrast, the IKs blocker chromanol 293B (10 to 30 μM) produced moderate prolongation of APD without EADs in all three tissue types. The combination of E–4031 (1 μM) and chromanol 293B (30 μM) resulted in profound prolongation of APD and the development of EADs in all three tissue types. In the perfused wedge, neither E–4031 nor chromanol 293B alone could induce EADs. In combination, the two drugs caused significant prolongation of APD and EADs in all three transmural regions.

Conclusion: Our results support the hypothesis that a prominent IKs is responsible for the ability of epicardium and endocardium to resist some but not all of the arrhythmogenic effects of IKr block. The data highlight the critical importance of IKs in the canine heart and the significant role of electrotonic interactions in minimizing the development of an arrhythmogenic substrate when repolarization reserve is reduced.
Kearns‐Sayre Syndrome: Association with Long QT Syndrome?
Authors: RASHID AHMAD , KIM MICHAEL H.
Published: August 2003

Kearns‐Sayre Syndrome. Kearns‐Sayre syndrome has associated cardiac findings, predominantly complete heart block, which has been implicated as a mechanism of sudden death in these individuals. A patient with Kearns‐Sayre syndrome who had syncope and multiple cardiac arrests due to ventricular tachycardia in the setting of QT prolongation is described. Long QT syndrome is implicated as another possibility for sudden death in Kearns‐Sayre syndrome. This potential association is unexplained, but now totals two reports in the small numbers of patients reported.
Tachycardia and Bradycardia Coexisting in the Same Pulmonary Vein
Authors: ORAL HAKAN , KNIGHT BRADLEY P. , TADA HIROSHI , MORADY FRED
Published: August 2003

Dissociated Pulmonary Vein Rhythms. During segmental isolation of the pulmonary veins (PVs) in a patient with paroxysmal atrial fibrillation, there was a PV bradycardia that was dissociated from the left atrium in a segment of the right superior PV, whereas the remaining segments showed passive activation of a PV fascicle during sinus rhythm. Rapid atrial pacing induced a PV tachycardia in the nonisolated fascicles, and the dissociated PV bradycardia persisted in a segment of the same PV. These observations indicate that PV fascicles are insulated from each other and that a dissociated PV rhythm does not necessarily indicate complete isolation of a PV.
Risk of Sudden Death After Successful Accessory Atrioventricular Pathway Ablation in Resuscitated Patients with Wolff‐Parkinson‐White Syndrome
Authors: ANTZ MATTHIAS , WEIß CHRISTIAN , VOLKMER MARIUS , HEBE JOACHIM , ERNST SABINE , OUYANG FEIFAN , KUCK KARL‐HEINZ
Published: August 2003

AP Ablation in Resuscitated WPW Patients.
Introduction: Cardiac arrest in patients with Wolff‐Parkinson‐White (WPW) syndrome can be due to ventricular fibrillation mediated by fast conduction over the accessory pathway during atrial fibrillation. However, if primary ventricular fibrillation is the reason for resuscitation, placement of an implantable cardioverter defibrillator (ICD) would be indicated. The aim of this study was to test the hypothesis that in resuscitated patients with WPW syndrome, recurrences can be prevented by sole ablation of their accessory pathways.

Methods and Results: We performed a long‐term follow‐up study of 48 resuscitated patients with WPW syndrome who underwent successful accessory pathway ablation as their sole primary treatment. Cardiac arrest had occurred either spontaneously in 32 patients (group A) or after intravenous administration of antiarrhythmic drugs in 16 patients (group B) and was never associated with an acute myocardial infarction or other concomitant factors. All patients had normal left ventricular function at echocardiography. A total of 56 accessory AV pathways were ablated successfully with radiofrequency current (n = 55) or during surgery (n = 1) and were located at the left free wall (n = 35), right free wall (n = 8), or septal‐paraseptal region (n = 13). Follow‐up 5.0 ± 1.9 years after ablation (range 0.2 to 7.9) was obtained in all 48 patients. All of the patients were alive, and none had a life‐threatening arrhythmia or syncope after successful ablation of their accessory pathways.

Conclusion: In resuscitated patients with WPW syndrome who have normal left ventricular function at echocardiography and no ECG abnormalities suggesting additional electrical disease, ablation of their overt accessory pathways prevented cardiac arrest recurrences; therefore, ICD placement is generally not indicated.
Radiofrequency Catheter Ablation of Idiopathic Ventricular Tachycardia Originating in the Main Stem of the Pulmonary Artery
Authors: TIMMERMANS CARL , RODRIGUEZ LUZ‐MARIA , MEDEIROS ARGELIA , CRIJNS HARRY J.G.M. , WELLENS HEIN J.J.
Published: August 2003

Idiopathic Pulmonary Artery Ventricular Tachycardia. We report the case of a patient in whom successful radiofrequency catheter ablation of an idiopathic ventricular tachycardia (VT) originating in the main stem of the pulmonary artery was performed. After successful ablation of the index arrhythmia, which was an idiopathic right ventricular outflow tract VT, a second VT with a different QRS morphology was reproducibly induced. Mapping of the second VT revealed the presence of myocardium approximately 2 cm above the pulmonary valve. Application of radiofrequency energy at this site resulted in termination and noninducibility of this VT. After 6‐month follow‐up, the patient remained free from VT recurrences.
Embolization of Pacing Electrode Fragment into the Superolateral Vein in the Spinal Canal Causing Root Compression
Authors: YILDIRIR AYLIN , BATUR MUSTAFA KEMAL , OTO ALI
Published: August 2003

Embolization of Pacing Electrode Fragment. Lead extraction may be complicated by lead fracture and embolization of the lead fragments into the pulmonary circulation or other vasculature causing various signs and symptoms. We present a very unusual case demonstrating embolization of a pacemaker electrode fragment into the superolateral vein in the spinal canal causing root compression. The electrode fragment was removed by spinal surgery, and the patient's symptoms gradually resolved.
Impaired Detection of Ventricular Tachyarrhythmias by a Rate‐Smoothing Algorithm in Dual‐Chamber Implantable Defibrillators: Intradevice Interactions
Authors: GLIKSON MICHAEL , BEEMAN AMY L. , LURIA DAVID M. , HAYES DAVID L. , FRIEDMAN PAUL A.
Published: August 2003

Rate‐Smoothing Algorithm in ICD.
Introduction: Rate smoothing is an algorithm initially designed to prevent rapid changes in pacemaker rates. In this study, we sought to determine the potential of the rate‐smoothing mechanism in preventing detection of ventricular tachyarrhythmias.

Methods and Results: Clinical testing of rate smoothing was performed at the time of defibrillator arrhythmia induction in 16 patients with implantable defibrillators during 65 episodes of ventricular tachyarrhythmias. We also performed simulator‐based testing to assess detection of ventricular tachycardia between 170 and 220 beats/min with systematic sequential change of rate‐smoothing percent, AV delay, and maximal rate. During clinical testing of 54 ventricular fibrillation/polymorphic ventricular tachyarrhythmia episodes, there were no cases of nondetection and 3 episodes (5%) of minimally delayed detection. Of 10 monomorphic ventricular tachyarrhythmias, 6 had either delayed (2 cases) or absent (4 cases) detection. During simulator testing, complex interrelationships were demonstrated in AV delay, upper rate, and rate‐smoothing percent in determining the severity of the effect on detection. Generally, long AV delay, higher upper rate, and smaller (more aggressive) rate smoothing were associated with increased risk of ventricular tachyarrhythmia underdetection. Importantly, use of parameters that impaired detection was always accompanied by a programmer warning message.

Conclusion: Rate smoothing may result in delay or failure of ventricular tachycardia detection. It is important to consider warning messages when programming rate smoothing and to test for appropriate detection when rate smoothing is used despite warning messages.
Lack of Benefit of an Active Pectoral Pulse Generator on Atrial Defibrillation Thresholds
Authors: GOLD MICHAEL R. , SHOROFSKY STEPHEN R. , BOUHOUCH RACHIDA , JOY ROBERT A. , KIRBY D. SCOTT , OSMAN AHMED F. , RASHBA ERIC J.
Published: August 2003

Effect of an Active Can on Atrial DFTs.
Introduction: Atrial defibrillation can be achieved with standard implantable cardioverter defibrillator leads, which has led to the development of combined atrial and ventricular devices. For ventricular defibrillation, use of an active pectoral electrode (active can) in the shocking pathway markedly reduces defibrillation thresholds (DFTs). However, the effect of an active pectoral can on atrial defibrillation is unknown.

Methods and Results: This study was a prospective, randomized, paired comparison of two shock configurations on atrial DFTs in 33 patients. The lead system evaluated was a dual‐coil transvenous defibrillation lead with a left pectoral pulse generator emulator. Shocks were delivered either between the right ventricular coil and proximal atrial coil (lead) or between the right ventricular coil and an active can in common with the atrial coil (active can). Delivered energy at DFT was 4.2 ± 4.1 J in the lead configuration and 5.0 ± 3.7 J in the active can configuration (P = NS). Peak current was 32% higher with an active can (P < 0.01), whereas shock impedance was 18% lower (P < 0.001). Moreover, a low threshold (< 3 J) was observed in 61% of subjects in the lead configuration but in only 36% in the active can configuration (P < 0.05). There were no clinical predictors of the atrial DFT.

Conclusion: These results indicate that low atrial DFTs can be achieved using a transvenous ventricular defibrillation lead. Because no benefit was observed with the use of an active pectoral electrode for atrial defibrillation, programmable shock vectors may be useful for dual‐chamber implantable cardioverter defibrillators.
Lack of Effect of Conduction Direction on Action Potential Durations in Anisotropic Ventricular Strips of Pig Heart
Authors: BERTRAN GUILLERMO , BIAGETTI MARCELO O. , VALVERDE ESTEBAN , ARINI PEDRO D. , QUINTEIRO RICARDO A.
Published: August 2003

Anisotropy and Repolarization.
Introduction: The influence of activation sequence on the rate of rise of the depolarization phase of action potentials in atrial or ventricular muscles has been well established. However, whether myocardial fiber orientation is important in modulating the repolarization process is unclear.

Methods and Results: We examined the influence of activation sequence on the repolarization phase of action potentials in epicardial tissues from the right and left ventricles of domestic pigs. Whereas cells from the right ventricle exhibited direction‐dependent differences in action potential duration at 30%, 50%, and 90% of full repolarization (190.6 ± 31.1 msec vs 181.8 ± 32.8 msec, 240.3 ± 23.5 msec vs 236.7 ± 25.4 msec, and 291.3 ± 23.7 msec vs 287.4 ± 25.1 msec for longitudinal and transverse propagation, respectively; P < 0.001), a similar duration of repolarization during both directions of propagation was observed in cells from the left ventricle at 50% and 90% of full repolarization (241.4 ± 39.4 msec and 285.5 ± 39.5 msec vs 240.4 ± 38.9 msec and 284.9 ± 39.6 msec for longitudinal and transverse propagation respectively; P = NS). A slight but significant difference was found at 30% of full repolarization in cells from the left ventricle (190.4 ± 39.0 msec vs 187.0 ± 38.0 msec for longitudinal and transverse propagation, respectively; P < 0.05). In the left ventricle, the duration of repolarization did not change as the distance between the recording site and stimulation site increased.

Conclusion: The direction of wavefront propagation with respect to fiber orientation may not play an important role in modulating the duration of repolarization in epicardial cells from the left ventricle.