527 research outputs found
Spontaneous degeneration of supraventricular tachycardia to ventricular fibrillation
No full textDarryl P. Leong, Martin K. Stiles, Bobby John, Dennis H. Lau, Glenn D. Young and Prashanthan Sander
Virtual anatomy for atrial fibrillation ablation
No full textThe definitive version is available at www.blackwell-synergy.comPrashanthan Sanders, Martin K. Stiles and Glenn D. Youn
Device therapy for rate control: pacing, resynchronisation and AV node ablation
No full textAbstract not availableDennis H. Lau, Anand Thiyagarajah, Stephan Willems, Thomas Rostock, Dominik Linz, Martin K. Stiles, David Kaye, Jonathan M. Kalman, Prashanthan Sander
Magnitude and Prognosis Associated With Ventricular Arrhythmias in Patients Hospitalized With Acute Coronary Syndromes (from the GRACE Registry)
No full textÁlvaro Avezum, Leopoldo S. Piegas, Robert J. Goldberg, David Brieger, Martin K. Stiles, Richard Paolini, Wei Huang, and Joel M. Gore, for the GRACE Investigator
Electrophysiological features of atrial flutter in cardiac sarcoidosis: a report of two cases
No full textWe report two cases of systemic sarcoidosis with atrial flutter as the clinical manifestation. In one patient, who had symptoms of shorter duration, the arrhythmia was no longer inducible after a course of glucocorticoid therapy. Electroanatomical mapping in the other case revealed patchy fibrosis of the left atrial myocardium and multiple macro-reentrant circuits. Sinus rhythm could be restored with ablation of these reentrant circuits. To our knowledge, this is the first report on the demonstration of atrial scarring in a patient with sarcoidosis using 3-D electroanatomical mapping. These two cases illustrate that the inflammation of atrial myocardium is the primary mechanism of atrial arrhythmias in patients with cardiac sarcoidosis.Narayanan Namboodiri, Martin K Stiles, Glenn D Young, Prashanthan Sander
Atrial fibrillation and anabolic steroid abuse
No full textCrown copyright © 2007 Published by Elsevier Ireland Ltd.Atrial fibrillation (AF) is the most common sustained arrhythmia to occur in humans. Several predisposing substrates such as increasing age, heart failure, hypertension and valvular heart disease have been identified. The use of illicit drugs as the substrate for AF is not frequently recognized.Dennis H. Lau, Martin K. Stiles, Bobby John, Shashidhar, Glenn D. Young and Prashanthan Sandershttp://www.elsevier.com/wps/find/journaldescription.cws_home/506041/description#descriptio
Defibrillator reset by radiotherapy
No full textThe number of patients with implantable cardioverter-defibrillator (ICD) is rapidly increasing due to their expanding indications. Amongst the various types of electromagnetic interferences, little is reported about the effects of radiotherapy. We report a case of electrical reset of a single chamber ICD by scattered irradiation from radiotherapy.Dennis H. Lau, Lauren Wilson, Martin K. Stiles, Bobby John, Shashidhar, Hany Dimitri, Anthony G. Brooks, Glenn D. Young and Prashanthan Sandershttp://www.elsevier.com/wps/find/journaldescription.cws_home/506041/description#descriptio
Targeting the Substrate in Ablation of Persistent Atrial Fibrillation: Recent Lessons and Future Directions
No full textWhile isolation of the pulmonary veins is firmly established as effective treatment for the majority of paroxysmal atrial fibrillation (AF) patients, there is recognition that patients with persistent AF have substrate for perpetuation of arrhythmia existing outside of the pulmonary veins. Various computational approaches have been used to identify targets for effective ablation of persistent AF. This paper aims to discuss the clinical aspects of computational approaches that aim to identify critical sites for treatment. Various analyses of electrogram characteristics have been performed with this aim. Leading techniques for electrogram analysis are Complex Fractionated Atrial Electrograms (CFAE) and Dominant Frequency (DF). These techniques have been the subject of clinical trials of which the results are discussed. Evaluation of the activation patterns of atria in AF has been another avenue of research. Focal Impulse and Rotor Modulation (FIRM) mapping and forms of Body Surface Mapping aim to characterize multiple atrial wavelets, macro-reentry and focal sources which have been proposed as basic mechanisms perpetuating AF. Both invasive and non-invasive activation mapping techniques are reviewed. The presence of atrial fibrosis causes non-uniform anisotropic impulse propagation. Therefore, identification of fibrosis by imaging techniques is an avenue of potential research. The leading contender for imaging-based techniques is Cardiac Magnetic Resonance (CMR). As this technology advances, improvements in resolution and scar identification have positioned CMR as the mode of choice for analysis of atrial structure. AF has been demonstrated to be associated with obesity, inactivity and diseases of modern life. An opportunity exists for detailed computational analysis of the impact of risk factor modification on atrial substrate. This ranges from microstructural investigation through to examination at a population level via registries and public health interventions. Computational analysis of atrial substrate has moved from basic science toward clinical application. Future directions and potential limitations of such analyses are examined in this review.Martin K. Stiles, Prashanthan Sanders and Dennis H. La
Reverse remodeling of the atria after treatment of chronic stretch in humans: implications for the atrial fibrillation substrate
No full textObjectivesThe aim of this report was to study the effect of chronic stretch reversal on the electrophysiological characteristics of the atria in humans.BackgroundAtrial stretch is an important determinant for atrial fibrillation. Whether relief of stretch reverses the substrate predisposed to atrial fibrillation is unknown.MethodsTwenty-one patients with mitral stenosis undergoing mitral commissurotomy (MC) were studied before and after intervention. Catheters were placed at multiple sites in the right atrium (RA) and sequentially within the left atrium (LA) to determine: effective refractory period (ERP) at 10 sites (600 and 450 ms) and P-wave duration (PWD). Bi-atrial electroanatomic maps determined conduction velocity (CV) and voltage. In 14 patients, RA studies were repeated >or=6 months after MC.ResultsImmediately after MC, there was significant increase in mitral valve area (2.1 +/- 0.2 cm(2), p ConclusionsThe atrial electrophysiologic and electroanatomic abnormalities that result from chronic stretch due to MS reverses after MC. These observations suggest that the substrate predisposing to atrial arrhythmias might be reversed.Bobby John, Martin K. Stiles, Pawel Kuklik, Anthony G. Brooks, Sunil T. Chandy, Jonathan M. Kalman, Prashanthan Sander
Comparison of the activity of selamectin, imidacloprid and fipronil for the treatment of cats infested experimentally with Ctenocephalides felis felis and Ctenocephalides felis strongylus
No full textTwenty adult, domestic short hair cats were randomly allocated into four groups of five cats and housed in separated cages. Each cat was infested with 25 fleas Ctenocephalides felis felis and 25 Ctenocephalides felis strongylus and 2 days later (day 0) the cats in group 1, 2 and 3 received a spot on application of selamectin, imidacloprid or fipronil, respectively, while the cats in group four were not treated. The cats were combed 48 h later, the fleas were removed, counted and their subspecies were determined. All the cats were reinfested with the same number of the two subspecies of fleas on days 7, 14, 21, 29 and 35. The efficacy of each treatment was calculated 48 h after each infestation. The mean number of fleas on the control cats was 16.4 C. f. felis and 13.4 C. f. strongylus. The three treatments were effective for the first 31 days for C. f. felis and for the full 37 days for C. f. strongylus. Over the first 31 days, the efficacy of selamectin ranged from 89 to 100% and 85 to 100% against C. f. felis and C. f. strongylus, respectively, the efficacy of imidacloprid ranged from 76 to 100% and 92 to 100% and the efficacy of fipronil ranged from 98 to 100% and 97 to 100% against C. f. felis and C. f. strongylus. There were no significant differences between the control of C. f. felis and C. f. strongylus by the three products
- …
