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S Walker

Bio: S Walker is an academic researcher from Harefield Hospital. The author has contributed to research in topics: Atrial fibrillation & Heart failure. The author has an hindex of 16, co-authored 29 publications receiving 4635 citations.

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Journal ArticleDOI
TL;DR: In this article, transvenous atriobiventricular pacemakers (with leads in one atrium and each ventricle) were used to reduce ventricular asynchrony.
Abstract: BACKGROUND: One third of patients with chronic heart failure have electrocardiographic evidence of a major intraventricular conduction delay, which may worsen left ventricular systolic dysfunction through asynchronous ventricular contraction. Uncontrolled studies suggest that multisite biventricular pacing improves hemodynamics and well-being by reducing ventricular asynchrony. We assessed the clinical efficacy and safety of this new therapy. METHODS: Sixty-seven patients with severe heart failure (New York Heart Association class III) due to chronic left ventricular systolic dysfunction, with normal sinus rhythm and a duration of the QRS interval of more than 150 msec, received transvenous atriobiventricular pacemakers (with leads in one atrium and each ventricle). This single-blind, randomized, controlled crossover study compared the responses of the patients during two periods: a three-month period of inactive pacing (ventricular inhibited pacing at a basic rate of 40 bpm) and a three-month period of active (atriobiventricular) pacing. The primary end point was the distance walked in six minutes; the secondary end points were the quality of life as measured by questionnaire, peak oxygen consumption, hospitalizations related to heart failure, the patients' treatment preference (active vs. inactive pacing), and the mortality rate. RESULTS: Nine patients were withdrawn from the study before randomization, and 10 failed to complete both study periods. Thus, 48 patients completed both phases of the study. The mean distance walked in six minutes was 22 percent greater with active pacing (399+/-100 m vs. 326+/-134 m, P<0.001), the quality-of-life score improved by 32 percent (P<0.001), peak oxygen uptake increased by 8 percent (P<0.03), hospitalizations were decreased by two thirds (P<0.05), and active pacing was preferred by 85 percent of the patients (P<0.001). CONCLUSIONS: Although it is technically complex, atriobiventricular pacing significantly improves exercise tolerance and quality of life in patients with chronic heart failure and intraventricular conduction delay.

2,540 citations

Journal ArticleDOI
TL;DR: Effective biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients with chronic atrial fibrillation and wide paced-QRS complexes.
Abstract: Background One third of chronic heart failure patients have major intraventricular conduction and uncoordinated ventricular contraction. Non-controlled studies suggest that biventricular pacing may improve haemodynamics and well-being by reducing ventricular asynchrony. The aim of this trial was to assess the clinical efficacy and safety of this new therapy in patients with chronic atrial fibrillation. Methods Fifty nine NYHA class III patients with left ventricular systolic dysfunction, chronic atrial fibrillation, slow ventricular rate necessitating permanent ventricular pacing, and a wide QRS complex (paced width ≥200ms), were implanted with transvenous biventricular-VVIR pacemakers. This single-blind, randomized, controlled, crossover study compared the patients’ parameters, as monitored during two 3-month treatment periods of conventional right-univentricular vs biventricular pacing. The primary end-point was the 6-min walked distance, secondary end-points were peak oxygen uptake, quality-of-life, hospitalizations, patients’ preferred study period and mortality. Results Because of a higher than expected drop-out rate (42%), only 37 patients completed both crossover phases. In the intention-to-treat analysis, we did not observe a significant difference. However, in the patients with effective therapy the mean walked distance increased by 9·3% with biventricular pacing (374±108 vs 342±103m in univentricular; P =0·05). Peak oxygen uptake increased by 13% ( P =0·04). Hospitalizations decreased by 70% and 85% of the patients preferred the biventricular pacing period ( P <0·001). Conclusion As compared with conventional VVIR pacing, effective biventricular pacing seems to improve exercise tolerance in NYHA class III heart failure patients with chronic atrial fibrillation and wide paced-QRS complexes. Further randomized controlled studies are required to definitively validate this therapy in such patients. Copyright 2002 The European Society of Cardiology. Published by Elsevier Science Ltd. All rights reserved .

463 citations

Journal ArticleDOI
T Levy1, G D Fotopoulos1, S Walker1, S. Rex1, M. Octave1, Vince Paul1, Mohammed Amrani1 
TL;DR: Biatrial pacing after CABG significantly decreases the incidence of AF and is associated with reduced postoperative complications and a trend toward reduced ICU and hospital stay.
Abstract: Background—Atrial fibrillation (AF) is a common problem after CABG. Prevention with prophylactic drug therapy has had limited success, therefore alternative approaches are required. This study investigated the role of biatrial pacing compared with no pacing on AF incidence after isolated first-time CABG. Methods and Results—During surgery, temporary pacing leads were placed in the lateral wall of the right atrium and at the roof of the left atrium in Bachmann’s bundle to allow bipolar pacing and sensing at each site. After surgery, all patients were connected to an external pacemaker (Chorum ELA) that also acted as a Holter monitor. Patients were consecutively randomized to either 4 days of biatrial pacing at a base rate of 80 bpm or to no pacing (control group, base rate 30 bpm). End points included an episode of AF lasting >1 hour on pacemaker Holter, clinically detected AF, intensive care unit (ICU) and hospital stay, and postoperative complications. One hundred thirty patients were randomized. Biatria...

113 citations

Journal ArticleDOI
S Walker1, T Levy1, S. Rex1, S Brant1, Jon Allen1, C Ilsley1, Vincent Paul1 
TL;DR: Comparative studies of circulating KL-6, type III procollagen N-terminal peptide and type IV collagen 7S in patients with interstitial pneumonitis and alveolar pneumonia and comparisons with previous studies suggest amiodarone induced pulmonary toxicity is likely.
Abstract: Circulating antigen KL-6 and lactate dehydrogenase for monitoring irradiated patients with lung cancer. Chest 1992;102:117–122. 11. Hamada H, Kohno N, Akiyama M, Hiwada K. Monitoring of serum KL-6 antigen in a patient with radiation pneumonia. Chest 1992;101:858–860. 12. Kohno N, Yokoyama A, Hirasawa Y, Kondo K, Fujino S, Abe M, Hiwada K. Comparative studies of circulating KL-6, type III procollagen N-terminal peptide and type IV collagen 7S in patients with interstitial pneumonitis and alveolar pneumonia. Respir Med 1997;91:558–561. 13. Polkey MI, Wilson POG, Rees PJ. Amiodarone pneumonitis: no safe dose. Respir Med 1995;89:233–235. 14. Jessurun GJ, Hoogenberg K, Crijns HJGM. Bronchiolitis obliterans organizing pneumonia during low-dose amiodarone therapy. Clin Cardiol 1997;20:300–302. 15. Pozzi E, Sada E, Luisetti M, De Rose V, Scelsi M. Interstitial pneumopathy and low-dosage amiodarone. Eur J Respir Dis 1984;65:620–622. 16. Martin WJ III, Rosenow EC III. Amiodarone pulmonary toxicity. Recognition and pathogenesis (part 2). Chest 1988;93:1242–1248. 17. Terra-Filho M, Meneghetti JC, Cukier A, Teixeira LR, Soares J, Camargo EE, Vargas FS. Gallium-67 lung imaging and pulmonary clearance of 99mTcDTPA aerosol in patients with amiodarone pneumonitis. Braz J Med Biol Res 1996;29:1467–1471. 18. Verswijvel G, Franssens Y, Deraemaeker L, Leyssens G, Govaerts E, Theunissen PH. Amiodarone induced pulmonary toxicity. J Belge Radiol 1998;81:9–10.

112 citations


Cited by
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Journal ArticleDOI
TL;DR: Authors/Task Force Members: Piotr Ponikowski* (Chairperson) (Poland), Adriaan A. Voors* (Co-Chair person) (The Netherlands), Stefan D. Anker (Germany), Héctor Bueno (Spain), John G. F. Cleland (UK), Andrew J. S. Coats (UK)

13,400 citations

Journal ArticleDOI
TL;DR: It is important that the medical profession play a significant role in critically evaluating the use of diagnostic procedures and therapies as they are introduced in the detection, management, and management of diseases.
Abstract: PREAMBLE......e4 APPENDIX 1......e121 APPENDIX 2......e122 APPENDIX 3......e124 REFERENCES......e124 It is important that the medical profession play a significant role in critically evaluating the use of diagnostic procedures and therapies as they are introduced in the detection, management,

8,362 citations

Journal ArticleDOI
TL;DR: ACCF/AHAIAI: angiotensin-converting enzyme inhibitor as discussed by the authors, angio-catabolizing enzyme inhibitor inhibitor inhibitor (ACS inhibitor) is a drug that is used to prevent atrial fibrillation.
Abstract: ACC/AHA : American College of Cardiology/American Heart Association ACCF/AHA : American College of Cardiology Foundation/American Heart Association ACE : angiotensin-converting enzyme ACEI : angiotensin-converting enzyme inhibitor ACS : acute coronary syndrome AF : atrial fibrillation

7,489 citations

Journal ArticleDOI
TL;DR: Authors/Task Force Members: Piotr Ponikowski* (Chairperson) (Poland), Adriaan A. Voors* (Co-Chair person) (The Netherlands), Stefan D. Anker (Germany), Héctor Bueno (Spain), John G. F. Cleland (UK), Andrew J. S. Coats (UK)
Abstract: ACC/AHA : American College of Cardiology/American Heart Association ACCF/AHA : American College of Cardiology Foundation/American Heart Association ACE : angiotensin-converting enzyme ACEI : angiotensin-converting enzyme inhibitor ACS : acute coronary syndrome AF : atrial fibrillation

6,757 citations

Journal ArticleDOI
TL;DR: Authors/Task Force Members: John J. McMurray (Chairperson) (UK), Stamatis Adamopoulos (Greece), Stefan D. Anker (Germany), Angelo Auricchio (Switzerland), Michael Böhm ( Germany), Kenneth Dickstein (Norway), Volkmar Falk (Sw Switzerland), Gerasimos Filippatos (G Greece), Cândida Fonseca (Portugal), Miguel Angel Gomez-Sanchez (Spain).
Abstract: Authors/Task Force Members: John J.V. McMurray (Chairperson) (UK)*, Stamatis Adamopoulos (Greece), Stefan D. Anker (Germany), Angelo Auricchio (Switzerland), Michael Böhm (Germany), Kenneth Dickstein (Norway), Volkmar Falk (Switzerland), Gerasimos Filippatos (Greece), Cândida Fonseca (Portugal), Miguel Angel Gomez-Sanchez (Spain), Tiny Jaarsma (Sweden), Lars Køber (Denmark), Gregory Y.H. Lip (UK), Aldo Pietro Maggioni (Italy), Alexander Parkhomenko (Ukraine), Burkert M. Pieske (Austria), Bogdan A. Popescu (Romania), Per K. Rønnevik (Norway), Frans H. Rutten (The Netherlands), Juerg Schwitter (Switzerland), Petar Seferovic (Serbia), Janina Stepinska (Poland), Pedro T. Trindade (Switzerland), Adriaan A. Voors (The Netherlands), Faiez Zannad (France), Andreas Zeiher (Germany).

6,367 citations