Research Topics
| G P WalcottSummaryAffiliation: University of Alabama at Birmingham Country: USA Publications
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Detail Information
Publications
Relative efficacy of monophasic and biphasic waveforms for transthoracic defibrillation after short and long durations of ventricular fibrillationG P Walcott
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, AL, USA
Circulation 98:2210-5. 1998..In protocol 2, we compared the efficacy of the more efficacious biphasic waveform from protocol 1, QSBW, with CDSMW after 15 seconds and 5 minutes of fibrillation...
Burst stimulation improves hemodynamics during resuscitation after prolonged ventricular fibrillationGregory Walcott
University of Alabama at Birmingham, Birmingham, AL, USA
Circ Arrhythm Electrophysiol 2:57-62. 2009..We hypothesized that a similar series of electrical pulses could increase myocardial function and blood pressure during the early post-resuscitation period...
Ventricular fibrillation threshold of rapid short pulsesGregory P Walcott
Cardiac Rhythm Management Laboratory, University of Alabama, Birmingham, USA
Conf Proc IEEE Eng Med Biol Soc 2011:255-8. 2011..This also allows for the risk assessment of CEWs by comparison to international electrical safety standards. The output of these weapons appears to be well below the VF risk limits as set by these standards...- Comparison of low-energy versus high-energy biphasic defibrillation shocks following prolonged ventricular fibrillationGregory P Walcott
Department of Medicine Division of Cardiovascular Diseases, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
Prehosp Emerg Care 14:62-70. 2010..This concern has been raised again with the development of the biphasic defibrillator... - Effect of timing and duration of a single chest compression pause on short-term survival following prolonged ventricular fibrillationGregory P Walcott
University of Alabama, B140 Volker Hall, 1670 University Blvd, Birmingham, AL 35294, United States
Resuscitation 80:458-62. 2009..Previous animal studies have shown that multiple pauses of increasing duration decrease resuscitation success. We investigated the effect of varying the characteristics of a single pause near defibrillation on resuscitation outcome... - Do clinically relevant transthoracic defibrillation energies cause myocardial damage and dysfunction?Gregory P Walcott
Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Volker Hall B140, 1670 University Blvd, Birmingham, AL 35294, USA
Resuscitation 59:59-70. 2003..Until those studies are completed, it seems reasonable to use the same 360 J (5 J/kg) energy limit for biphasic shocks as for monophasic shocks... - Effects of burst stimulation during ventricular fibrillation on cardiac function after defibrillationGregory P Walcott
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama, 1670 University Blvd, Birmingham, AL 35294, USA
Am J Physiol Heart Circ Physiol 285:H766-74. 2003..beta-Blockade or reserpine pretreatment prevents most of this postshock increase in HR, arterial pressure, and LV pressure... - Defibrillation with a minimally invasive direct cardiac massage deviceGregory P Walcott
University of Alabama at Birmingham, 1530 3rd Ave So, Volker Hall B140, 35294 0019, USA
Resuscitation 55:301-7. 2002.... - Biphasic waveform external defibrillation thresholds for spontaneous ventricular fibrillation secondary to acute ischemiaGregory P Walcott
Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294 0019, USA
J Am Coll Cardiol 39:359-65. 2002.... - Endocardial wave front organization during ventricular fibrillation in humansGregory P Walcott
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
J Am Coll Cardiol 39:109-15. 2002..This study was designed to characterize the organization of ventricular fibrillation (VF) on the endocardium of humans... - Atrial defibrillation thresholds of electrode configurations available to an atrioventricular defibrillatorM E Benser
Cardiac Rhythm Management Laboratory, Guidant Corporation, St Paul, Minnesota, USA
J Cardiovasc Electrophysiol 12:957-64. 2001..We also tested the atrial defibrillation thresholds of five other configurations... - Pacing during ventricular fibrillation: factors influencing the ability to captureJ C Newton
Department of Physiology and Biophysics, University of Alabama at Birmingham, 35294, USA
J Cardiovasc Electrophysiol 12:76-84. 2001..CONCLUSION: The probability of a pacing train capturing fibrillating myocardium can be influenced by the pacing protocol parameters... - A telemetry system for the study of spontaneous cardiac arrhythmiasD L Rollins
Department of Medicine, University of Alabama at Birmingham 35294, USA
IEEE Trans Biomed Eng 47:887-92. 2000..Approximately 12 h of 14,000 bytes/s data can be collected with each set of batteries. The system is suitable for continuous monitoring of animal models of spontaneous arrhythmias and sudden cardiac death... - Improvement of defibrillation efficacy and quantification of activation patterns during ventricular fibrillation in a canine heart failure modelJ Huang
Department of Medicine, University of Alabama at Birmingham, USA
Circulation 103:1473-8. 2001..CONCLUSIONS: HF increases the DFT. This is partially reversed by an auxiliary shock. HF markedly changes VF activation patterns... - Continuous telemetry from a chronic canine model of sudden cardiac deathC R Killingsworth
Department of Medicine, University of Alabama at Birmingham, 35294 0019, USA
J Cardiovasc Electrophysiol 11:1333-41. 2000..We sought to develop a continuously telemetered animal model of sudden cardiac death (SCD) to study the role of existing infarcts and acute ischemia in fatal arrhythmias... - Comparison of the temperature profile and pathological effect at unipolar, bipolar and phased radiofrequency current configurationsX Zheng
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, AL 35294, USA
J Interv Card Electrophysiol 5:401-10. 2001..As judged by tissue temperature, lesion depth and uniformity, and RF power requirement, 127 degrees RF may be a better energy configuration for linear ablation than the other RF modalities tested... - The relationship of defibrillation and stimulation: design implications for the optimum defibrillation waveformR E Ideker
Department of Medicine, University of Alabama, Volker Hall B 140A 1670 University Blvd, Birmingham, AL 35292-0019, USA
Europace 5:245-6. 2003 - Right atrial septal electrode for reducing the atrial defibrillation thresholdX Zheng
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama, Birmingham, USA
Circulation 104:1066-70. 2001..CONCLUSIONS: The ADFT of the standard RAA-->CS configuration may be markedly reduced with an additional electrode situated at the RSP... - Comparison of six clinically used external defibrillators in swineRobert G Walker
Medtronic Physio Control Corporation, 11811 Willows Road NE, 98073 9706, Redmond, WA, USA
Resuscitation 57:73-83. 2003.... - Lifetimes of epicardial rotors in panoramic optical maps of fibrillating swine ventriclesMatthew W Kay
Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA
Am J Physiol Heart Circ Physiol 291:H1935-41. 2006..This paucity of persistent rotors suggests that individual rotors will eventually terminate by themselves and therefore that the continual formation of new rotors is critical for VF maintenance... - Panoramic optical mapping reveals continuous epicardial reentry during ventricular fibrillation in the isolated swine heartJack M Rogers
Department of Biomedical Engineering, University of Alabama, Birmingham, Alabama, USA
Biophys J 92:1090-5. 2007..These data suggest that VF in this model is not driven by localized sources; thus, new anti-VF treatments designed to target such sources may be less effective than global interventions... - Porcine defibrillation thresholds with chopped biphasic truncated exponential waveformsJoseph L Sullivan
Medtronic Emergency Response Systems, 11811 Willows Rd NE, P O Box 97006, Redmond, WA 98073 9706, USA
Resuscitation 74:325-31. 2007..Previous studies comparing chopped and unchopped waveforms have found conflicting results. This study compared the defibrillation thresholds (DFTs) of a variety of chopped and unchopped BTE waveforms... - Chemical ablation of the Purkinje system causes early termination and activation rate slowing of long-duration ventricular fibrillation in dogsDerek J Dosdall
Volker Hall B140, 1670 Univ Blvd, Birmingham, AL 35294 0019, USA
Am J Physiol Heart Circ Physiol 295:H883-9. 2008..Ablation of the subendocardium hastens VF spontaneous termination and alters VF activation sequences, suggesting that Purkinje fibers are important in the maintenance of LDVF... - Reduction of the internal atrial defibrillation threshold with balanced orthogonal sequential shocksXiangsheng Zheng
J Cardiovasc Electrophysiol 13:904-9. 2002.... - Impact of myocardial ischemia and reperfusion on ventricular defibrillation patterns, energy requirements, and detection of recoveryHao Qin
Department of Physiology and Biophysics, Medicine, University of Alabama at Birmingham, 35294-0019, USA
Circulation 105:2537-42. 2002..6+/-5.3 seconds. CONCLUSIONS: Spontaneous VF can be halted by a shock but then quickly restart before a standard ECG amplifier has recovered from postshock saturation, making it appear that the shock failed... - Effect of electrode location in great cardiac vein on the ventricular defibrillation thresholdJian Huang
Departments of Medicine, Biomedical Engineering and Physiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
Pacing Clin Electrophysiol 25:42-8. 2002..001). Application of an auxiliary shock to the apical region, near the region where previous studies have indicated that the RV primary shock has its weakest effects, caused the greatest decrease in DFT... - Chronic myocardial infarction is a substrate for bradycardia-induced spontaneous tachyarrhythmias and sudden death in conscious animalsCheryl R Killingsworth
Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, 35294 0019, USA
J Cardiovasc Electrophysiol 17:189-97. 2006..We tested the hypothesis that MI and bradycardia cause more spontaneous sustained VT than does bradycardia alone... - Evidence that activation following failed defibrillation is not caused by triggered activityXiangsheng Zheng
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Alabama, USA
J Cardiovasc Electrophysiol 16:1200-5. 2005.... - Mechanisms for the maintenance of ventricular fibrillation: the nonuniform dispersion of refractoriness, restitution properties, or anatomic heterogeneities?Hao Qin
Department of Medicine, University of Alabama, Birmingham, Alabama 35294, USA
J Cardiovasc Electrophysiol 16:888-97. 2005..The relative importance of nonuniform dispersion of refractoriness, steep restitution slopes, and anatomic heterogeneities in causing conduction block during ventricular fibrillation (VF) remains unknown... - Activation sequences following failed atrial defibrillationXiangsheng Zheng
Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, 35294, USA
Heart Rhythm 1:616-23. 2004..4) The region of earliest postshock activation in the failed episodes without a focal postshock activation pattern exhibited regions of fragmented electrogram derivatives that may represent conduction block and possibly reentry... - Defibrillation threshold and cardiac responses using an external biphasic defibrillator with pediatric and adult adhesive patches in pediatric-sized pigletsCheryl R Killingsworth
Cardiac Rhythm Management Laboratory, Department of Medicine, Division of Cardiovascular Diseases, University of Alabama at Birmingham, 1670 University Boulevard, B140 Volker Hall, Birmingham, AL 35294, USA
Resuscitation 55:177-85. 2002..These data suggest that there is a substantial safety margin above a DFT strength shock for this biphasic waveform in piglets... - Ventricular fibrillation and defibrillation--what are the major unresolved issues?Raymond E Ideker
Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama 35294 0019, USA
Heart Rhythm 2:555-8. 2005 - Short-acting beta-adrenergic antagonist esmolol given at reperfusion improves survival after prolonged ventricular fibrillationCheryl R Killingsworth
Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, AL 35294 0019, USA
Circulation 109:2469-74. 2004.... - Emission ratiometry for simultaneous calcium and action potential measurements with coloaded dyes in rabbit hearts: reduction of motion and driftWei Kong
Department of Biomedical Engineering of the School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7575, USA
J Cardiovasc Electrophysiol 14:76-82. 2003..6 (P < 0.05) for Ca and 0.45 (P < 0.05) for AP. CONCLUSION: Simultaneous Ca and AP emission ratiometry reduces motion artifacts and drift in hearts with coloaded dyes... - Identification of transmural necrosis along a linear catheter ablation lesion during atrial fibrillation and sinus rhythmJavier E Sanchez
Department of Internal Medicine, Division of Cardiovascular Diseases, Cardiac Rhythm Management Laboratory, University of Alabama at Birmingham, Birmingham, AL 35294, USA
J Interv Card Electrophysiol 8:9-17. 2003..Termination of atrial fibrillation may not be necessary to estimate the histologic characteristics of an ablation lesion... - Epicardial organization of human ventricular fibrillationKumaraswamy Nanthakumar
Division of Cardiovascular Medicine, University of Alabama at Birmingham, 35294, USA
Heart Rhythm 1:14-23. 2004..The objective of this study was to test the hypothesis that on the epicardium of the in vivo human heart, ventricular fibrillation (VF) consists of chaotic small wavefronts that constantly change paths... - Ecclesiastes, cardiac arrest, and the electrocardiogramRaymond E Ideker
Pacing Clin Electrophysiol 28:607-9. 2005