The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
Nabil Elsherif - One of the best experts on this subject based on the ideXlab platform.
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a unified functional anatomic substrate for circus movement Atrial flutter activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil ElsherifAbstract:OBJECTIVES: This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. BACKGROUND: The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. METHODS: In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. RESULTS: Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination required the arc of block to rejoin the AV ring. Inducibility of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. CONCLUSIONS: Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the development of functional conduction block.
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a unified functional anatomic substrate for circus movement Atrial flutter activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil ElsherifAbstract:Objectives. This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. Background. The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. Methods. In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. Results. Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination repuired the arc of block to rejoin the AV ring. Inducibillity of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. Conclusions. Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the devlopment of functional conduction block
Wolfgang Schoels - One of the best experts on this subject based on the ideXlab platform.
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a unified functional anatomic substrate for circus movement Atrial flutter activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil ElsherifAbstract:OBJECTIVES: This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. BACKGROUND: The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. METHODS: In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. RESULTS: Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination required the arc of block to rejoin the AV ring. Inducibility of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. CONCLUSIONS: Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the development of functional conduction block.
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a unified functional anatomic substrate for circus movement Atrial flutter activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil ElsherifAbstract:Objectives. This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. Background. The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. Methods. In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. Results. Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination repuired the arc of block to rejoin the AV ring. Inducibillity of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. Conclusions. Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the devlopment of functional conduction block
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A unified functional/anatomic substrate for circus movement Atrial flutter: Activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil El-sherifAbstract:Objectives. This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. Background. The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. Methods. In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. Results. Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination repuired the arc of block to rejoin the AV ring. Inducibillity of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. Conclusions. Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the devlopment of functional conduction block
Nabil El-sherif - One of the best experts on this subject based on the ideXlab platform.
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Efficacy of azimilide and dofetilide in the dog Right Atrial Enlargement model of Atrial flutter.
Journal of cardiovascular electrophysiology, 2001Co-Authors: Mark Restivo, Maha Hegazy, Moustafa El-hamami, Hong Yin, Edward B. Caref, Mahshid A. Assadi, Robert R. Brooks, Nabil El-sherifAbstract:Azimilide and Dofetilide Atrial Flutter Efficacy.Introduction: Azimilide dihydrochloride blocks both the rapid (IKr) and slow (IKs) components of the delayed rectified K+ current; dofetilide blocks only IKr. Their efficacies were assessed on Atrial flutter reentrant circuits in dogs with surgically induced Right Atrial Enlargement. Methods and Results: Multiple biopsies of the tricuspid valve and banding of the pulmonary artery in male mongrel dogs made them susceptible, about 3 weeks postoperatively, to stimulation-induced sustained (5 min or longer) Atrial flutter. Azimilide 3 mg/kg administered intravenously (IV) terminated flutter in 8 of 8 dogs, but a slower, nonsustained arrhythmia could be reinduced in 5. In these 5 dogs, azimilide 10 mg/kg terminated flutter and prevented reinduction. This dose increased effective refractory period significantly more in the slow conduction zone (25%) than in the normal zone (17%) and increased flutter cycle length (37%). Termination followed progressive conduction delay in the slow zone of the reentrant circuit. Dofetilide 1 μg/kg IV terminated flutter in 6 of 6 dogs, but the arrhythmia could be reinduced. At 3 μg/kg, flutter terminated in all dogs and could not be reinduced. Dofetilide also increased the effective refractory period significantly more in the slow zone (17%) than in the normal zone (12%) and increased cycle length (33%), leading to interruption of the arrhythmia circuit. Conclusion: In the canine Right Atrial Enlargement model of circus movement Atrial flutter, both azimilide 10 mg/kg IV and dofetilide 3 μg/kg IV were 100% effective in terminating flutter and preventing reinduction. Efficacy relied on a similar mechanism of differentially prolonged refractoriness in the slow conduction component of the reentrant circuit where drug-induced termination occurred.
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A unified functional/anatomic substrate for circus movement Atrial flutter: Activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil El-sherifAbstract:Objectives. This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. Background. The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. Methods. In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. Results. Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination repuired the arc of block to rejoin the AV ring. Inducibillity of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. Conclusions. Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the devlopment of functional conduction block
Judy R. Mangion - One of the best experts on this subject based on the ideXlab platform.
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Ostium Secundum Atrial Septal Defect
The New England journal of medicine, 1995Co-Authors: Judy R. MangionAbstract:Figure 1. The electrocardiogram of a 42-year-old woman with the ostium secundum type of Atrial septal defect shows normal sinus rhythm with incomplete Right bundle-branch block (RBBB), indicated by the rSR' pattern in leads V1 and V2 and the terminal S wave in V6; Right Atrial Enlargement (RAE), indicated by the tall P waves in leads II, III, and aVF; and Right ventricular hypertrophy (RVH), indicated by the tall R waves in leads V1 and V2. The chest radiograph of the same patient shows a globular cardiac silhouette with prominent pulmonary arteries (p); . . .
Wolfgang Kuebler - One of the best experts on this subject based on the ideXlab platform.
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a unified functional anatomic substrate for circus movement Atrial flutter activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil ElsherifAbstract:OBJECTIVES: This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. BACKGROUND: The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. METHODS: In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. RESULTS: Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination required the arc of block to rejoin the AV ring. Inducibility of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. CONCLUSIONS: Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the development of functional conduction block.
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a unified functional anatomic substrate for circus movement Atrial flutter activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil ElsherifAbstract:Objectives. This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. Background. The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. Methods. In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. Results. Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination repuired the arc of block to rejoin the AV ring. Inducibillity of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. Conclusions. Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the devlopment of functional conduction block
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A unified functional/anatomic substrate for circus movement Atrial flutter: Activation and refractory patterns in the canine Right Atrial Enlargement model
Journal of the American College of Cardiology, 1993Co-Authors: Wolfgang Schoels, Wolfgang Kuebler, H Yang, William B Gough, Nabil El-sherifAbstract:Objectives. This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on Right Atrial Enlargement and to elucidate the electrophysiologic basis for functional conduction block. Background. The monotonic feature of Atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower Right atrium to single-loop reentry. Methods. In 11 dogs with Right Atrial Enlargement, 127 bipolar epicardial electrograms were obtained during Atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. Results. Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination repuired the arc of block to rejoin the AV ring. Inducibillity of sustained Atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. Conclusions. Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the devlopment of functional conduction block
