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Post-operative atrial fibrillation management by selective epicardial vagal fat pad stimulation. J Interv Card Electrophysiol 2008; 24:37-45. [PMID: 18758932 DOI: 10.1007/s10840-008-9286-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Accepted: 05/29/2008] [Indexed: 12/21/2022]
Abstract
PURPOSE Post-operative atrial fibrillation (POAF) is a common complication after cardiac surgery and often leads to poorly tolerated fast ventricular rates. Negative dromotropic drugs are not always effective and may not be well tolerated in heart failure patients. Aim of this study is to verify if high-frequency stimulation of the right inferior fat pad (RIFPS) allows an effective decrease in ventricular rate (VR) during POAF. METHODS We enrolled 32 consecutive patients submitted to bypass; during surgery, a temporary heart wire was implanted in a site where RIFPS evoked a functional AV block. During POAF, RIFPS was delivered from the heart wire to decrease VR. RESULTS Intra-operative RIFPS evoked complete AV block in 29 patients (91%). Fourteen patients (44%) developed POAF (mean VR 127 +/- 12 bpm). In these patients, RIFPS achieved a 25% reduction of VR and complete AV block with 6.0 +/- 1.9 and 7.5 +/- 1.8 V (duration 0.2 ms, frequency 50 Hz), respectively. CONCLUSION Epicardial RIFPS represents an effective and feasible technique to decrease VR during POAF.
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152
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Richer LP, Vinet A, Kus T, Cardinal R, Ardell JL, Armour JA. Alpha-adrenoceptor blockade modifies neurally induced atrial arrhythmias. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1175-80. [PMID: 18716036 DOI: 10.1152/ajpregu.00840.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our objective was to determine whether neuronally induced atrial arrhythmias can be modified by alpha-adrenergic receptor blockade. In 30 anesthetized dogs, trains of five electrical stimuli (1 mA; 1 ms) were delivered immediately after the P wave of the ECG to mediastinal nerves associated with the superior vena cava. Regional atrial electrical events were monitored with 191 atrial unipolar electrodes. Mediastinal nerve sites were identified that reproducibly initiated atrial arrhythmias. These sites were then restimulated following 1 h (time control, n = 6), or the intravenous administration of naftopidil (alpha(1)-adrenergic blocker: 0.2 mg/kg, n = 6), yohimbine (alpha(2)-adrenergic blocker: 1 mg/kg, n = 6) or both (n = 8). A ganglionic blocker (hexamethonium: 1 mg/kg) was tested in four dogs. Stimulation of mediastinal nerves sites consistently elicited atrial tachyarrhythmias. Repeat stimulation after 1 h in the time-control group exerted a 19% decrease of the sites still able to induce atrial tachyarrhythmias. Hexamethonium inactivated 78% of the previously active sites. Combined alpha-adrenoceptor blockade inactivated 72% of the previously active sites. Bradycardia responses induced by mediastinal nerve stimulation were blunted by hexamethonium, but not by alpha(1,2)-adrenergic blockade. Naftopidil or yohimbine alone eliminated atrial arrhythmia induction from 31% and 34% of the sites (similar to time control). We conclude that heterogeneous activation of the intrinsic cardiac nervous system results in atrial arrhythmias that involve intrinsic cardiac neuronal alpha-adrenoceptors. In contrast to the global suppression exerted by hexamethonium, we conclude that alpha-adrenoceptor blockade targets intrinsic cardiac local circuit neurons involved in arrhythmia formation and not the flow-through efferent projections of the cardiac nervous system.
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153
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LU ZHIBING, SCHERLAG BENJAMINJ, LIN JIAXIONG, NIU GUODONG, GHIAS MUHAMMAD, JACKMAN WARRENM, LAZZARA RALPH, JIANG HONG, PO SUNNYS. Autonomic Mechanism for Complex Fractionated Atrial Electrograms: Evidence by Fast Fourier Transform Analysis. J Cardiovasc Electrophysiol 2008; 19:835-42. [DOI: 10.1111/j.1540-8167.2008.01131.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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154
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SCHERLAG BENJAMINJ, HOU YINGLONG, LIN JIAXIONG, LU ZHIBING, ZACHARIAS SONI, DASARI TARUN, NIU GUODONG, GHIAS MUHAMMAD, PATTERSON EUGENE, JACKMAN WARRENM, LAZZARA RALPH, PO SUNNYS. An Acute Model for Atrial Fibrillation Arising from a Peripheral Atrial Site: Evidence for Primary and Secondary Triggers. J Cardiovasc Electrophysiol 2008; 19:519-27. [DOI: 10.1111/j.1540-8167.2007.01087.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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155
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Lu Z, Scherlag BJ, Lin J, Niu G, Fung KM, Zhao L, Ghias M, Jackman WM, Lazzara R, Jiang H, Po SS. Atrial fibrillation begets atrial fibrillation: autonomic mechanism for atrial electrical remodeling induced by short-term rapid atrial pacing. Circ Arrhythm Electrophysiol 2008; 1:184-92. [PMID: 19808412 DOI: 10.1161/circep.108.784272] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND The mechanism(s) for acute changes in electrophysiological properties of the atria during rapid pacing induced atrial fibrillation (AF) is not completely understood. We sought to evaluate the contribution of the intrinsic cardiac autonomic nervous system in acute atrial electrical remodeling and AF induced by 6-hour rapid atrial pacing. METHODS AND RESULTS Continuous rapid pacing (1200 bpm, 2x threshold [TH]) was performed at the left atrial appendage. Group 1 (n=7) underwent 6-hour pacing immediately followed by ganglionated plexi (GP) ablation; group 2 (n=7) underwent GP ablation immediately followed by 6-hour pacing; and group 3 (n=4) underwent administration of autonomic blockers, atropine (1 mg/kg), and propranolol (0.6 mg/kg) immediately followed by 6-hour pacing. The effective refractory period (ERP) and window of vulnerability (WOV, in milliseconds), ie, the difference between the longest and the shortest coupling interval of the premature stimulus that induced AF, were measured at 2xTH and 10xTH at the left atrium, right atrium, and pulmonary veins every hour before and after GP ablation or autonomic blockade. In group 1, ERP was markedly shortened in the first 2 hours and then stabilized both at 2xTH and 10xTH; however, WOV was progressively widened throughout the 6-hour period. After GP ablation, ERP was significantly longer than before ablation and AF could not be induced (WOV=0) at either 2xTH or 10xTH. In groups 2 and 3, rapid atrial pacing failed to shorten the ERP. AF could not be induced in 6 of 7 dogs in group 2 and all 4 dogs in group 3 during the 6-hour pacing period. CONCLUSIONS The intrinsic cardiac autonomic nervous system plays a crucial role in the acute stages of atrial electrical remodeling induced by rapid atrial pacing.
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Affiliation(s)
- Zhibing Lu
- Department of Cardiology, Renmin Hospital of Wuhan University, Wuhan, China
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156
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Pokushalov E, Turov A, Shugayev P, Artyomenko S, Romanov A, Shirokova N. Catheter Ablation of Left Atrial Ganglionated Plexi for Atrial Fibrillation. Asian Cardiovasc Thorac Ann 2008; 16:194-201. [DOI: 10.1177/021849230801600304] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Radiofrequency ablation of pulmonary vein ostia does not provide complete and long-term elimination of atrial fibrillation. Combining this procedure with local radiofrequency application on sites with strong vagal reflexes results in partial parasympathetic denervation and increases the antiarrhythmic effect. A novel catheter-ablation technique to modify ganglionated plexi in the left atrium was assessed in 58 patients (mean age, 52.1 ± 1.9 years, 67% male) with drug-refractory atrial fibrillation, which was chronic in 21 (36%; mean duration, 14.3 ± 2.9 months; range, 5–39 months). The mean left atrial volume was 93.1 ± 6.1 mL. The patients underwent ablation of 4 areas of ganglionated plexi in the left atrium, with no circumferential ablation of the pulmonary veins; atrial fibrillation ceased immediately in 94.1% of them. Transient vagal bradycardia was seen in 93% of patients. For 7.2 ± 0.4 months after the procedure, 86.2% of them were free from arrhythmias, and no antiarrhythmic drugs were administered. Ganglionated plexi ablation is an efficient treatment for atrial fibrillation.
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Affiliation(s)
| | - Alex Turov
- State Research Institute of Circulation Pathology Novosibirsk, Russia
| | - Pavel Shugayev
- State Research Institute of Circulation Pathology Novosibirsk, Russia
| | - Sergey Artyomenko
- State Research Institute of Circulation Pathology Novosibirsk, Russia
| | - Alex Romanov
- State Research Institute of Circulation Pathology Novosibirsk, Russia
| | - Natalya Shirokova
- State Research Institute of Circulation Pathology Novosibirsk, Russia
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157
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Innervation of pulmonary veins: Morphologic pattern and pathways of nerves in the human fetus. Ann Anat 2008; 190:158-66. [DOI: 10.1016/j.aanat.2007.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2007] [Revised: 09/04/2007] [Accepted: 09/11/2007] [Indexed: 11/18/2022]
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158
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Anatomical pitfalls during encircling cryoablation of the left atrium for atrial fibrillation therapy in the pig. J Interv Card Electrophysiol 2008; 21:187-93. [DOI: 10.1007/s10840-008-9205-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Accepted: 01/08/2008] [Indexed: 11/25/2022]
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159
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Oral H, Crawford T, Frederick M, Gadeela N, Wimmer A, Dey S, Sarrazin JF, Kuhne M, Chalfoun N, Wells D, Good E, Jongnarangsin K, Chugh A, Bogun F, Pelosi F, Morady F. Inducibility of paroxysmal atrial fibrillation by isoproterenol and its relation to the mode of onset of atrial fibrillation. J Cardiovasc Electrophysiol 2008; 19:466-70. [PMID: 18266669 DOI: 10.1111/j.1540-8167.2007.01089.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Isoproterenol has been used to assess inducibility during catheter ablation for paroxysmal PAF. However, no studies have determined the sensitivity and specificity of isoproterenol for the induction of AF. It also is not clear whether isoproterenol is equally effective in inducing AF in the clinical subtypes of vagotonic, adrenergic, and random AF. OBJECTIVE To determine the sensitivity and specificity of isoproterenol for the induction of atrial fibrillation (AF). METHODS Isoproterenol was infused at 5, 10, 15, and 20 microg/min at 2-minute intervals or until AF was induced in 20 control subjects with no history of AF and in 80 patients with PAF. RESULTS Among the 20 control subjects, AF was induced by isoproterenol in one patient (5%). Among the 80 patients with PAF, persistent AF was induced in 67 patients (84%, P < 0.001). Isoproterenol induced AF in 15 of 17 patients (88%) with vagotonic AF, 11 of 11 patients (100%) with adrenergic AF, and 41 of 52 patients (79%) with random episodes of AF (P = 0.2). The yield of AF was 11% (9/80) after 5 microg/min, 28% (22/80) after 10 microg/min, 51% (40/78) after 15 microg/min, and 88% (67/76) after 20 microg/min of isoproterenol (P < 0.01). Isoproterenol had to be discontinued in four patients (5%) before reaching the maximum dose due to reversible chest pain or systolic blood pressure <85 mmHg. CONCLUSIONS Isoproterenol at infusion rates up to 20 microg/min has a high sensitivity (88%) and specificity (95%) for induction of AF in patients with PAF, regardless of whether the clinical subtype is vagotonic, adrenergic, or random.
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Affiliation(s)
- Hakan Oral
- Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA.
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160
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Lemola K, Chartier D, Yeh YH, Dubuc M, Cartier R, Armour A, Ting M, Sakabe M, Shiroshita-Takeshita A, Comtois P, Nattel S. Pulmonary vein region ablation in experimental vagal atrial fibrillation: role of pulmonary veins versus autonomic ganglia. Circulation 2008; 117:470-7. [PMID: 18195170 DOI: 10.1161/circulationaha.107.737023] [Citation(s) in RCA: 166] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pulmonary vein (PV) -encircling radiofrequency ablation frequently is effective in vagal atrial fibrillation (AF), and there is evidence that PVs may be particularly prone to cholinergically induced arrhythmia mechanisms. However, PV ablation procedures also can affect intracardiac autonomic ganglia. The present study examined the relative role of PVs versus peri-PV autonomic ganglia in an experimental vagal AF model. METHODS AND RESULTS Cholinergic AF was studied under carbachol infusion in coronary perfused canine left atrial PV preparations in vitro and with cervical vagal stimulation in vivo. Carbachol caused dose-dependent AF promotion in vitro, which was not affected by excision of all PVs. Sustained AF could be induced easily in all dogs during vagal nerve stimulation in vivo both before and after isolation of all PVs with encircling lesions created by a bipolar radiofrequency ablation clamp device. PV elimination had no effect on atrial effective refractory period or its responses to cholinergic stimulation. Autonomic ganglia were identified by bradycardic and/or tachycardic responses to high-frequency subthreshold local stimulation. Ablation of the autonomic ganglia overlying all PV ostia suppressed the effective refractory period-abbreviating and AF-promoting effects of cervical vagal stimulation, whereas ablation of only left- or right-sided PV ostial ganglia failed to suppress AF. Dominant-frequency analysis suggested that the success of ablation in suppressing vagal AF depended on the elimination of high-frequency driver regions. CONCLUSIONS Intact PVs are not needed for maintenance of experimental cholinergic AF. Ablation of the autonomic ganglia at the base of the PVs suppresses vagal responses and may contribute to the effectiveness of PV-directed ablation procedures in vagal AF.
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Affiliation(s)
- Kristina Lemola
- Department of Medicine, Montreal Heart Institute, Montreal, Quebec, Canada
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161
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162
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Arora R, Ulphani JS, Villuendas R, Ng J, Harvey L, Thordson S, Inderyas F, Lu Y, Gordon D, Denes P, Greene R, Crawford S, Decker R, Morris A, Goldberger J, Kadish AH. Neural substrate for atrial fibrillation: implications for targeted parasympathetic blockade in the posterior left atrium. Am J Physiol Heart Circ Physiol 2008; 294:H134-44. [DOI: 10.1152/ajpheart.00732.2007] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The parasympathetic (P) nervous system is thought to contribute significantly to focal atrial fibrillation (AF). Thus we hypothesized that P nerve fibers [and related muscarinic (M2) receptors] are preferentially located in the posterior left atrium (PLA) and that selective cholinergic blockade in the PLA can be successfully performed to alter vagal AF substrate. The PLA, pulmonary veins (PVs), and left atrial appendage (LAA) from six dogs were immunostained for sympathetic (S) nerves, P nerves, and M2 receptors. Epicardial electrophysiological mapping was performed in seven additional dogs. The PLA was the most richly innervated, with nerve bundles containing P and S fibers (0.9 ± 1, 3.2 ± 2.5, and 0.17 ± 0.3/cm2 in the PV, PLA, and LAA, respectively, P < 0.001); nerve bundles were located in fibrofatty tissue as well as in surrounding myocardium. P fibers predominated over S fibers within bundles (P-to-S ratio = 4.4, 7.2, and 5.8 in PV, PLA, and LAA, respectively). M2 distribution was also most pronounced in the PLA (17.8 ± 8.3, 14.3 ± 7.3, and 14.5 ± 8 M2-stained cells/cm2 in the PLA, PV, and LAA, respectively, P = 0.012). Left cervical vagal stimulation (VS) caused significant effective refractory period shortening in all regions, with easily inducible AF. Topical application of 1% tropicamide to the PLA significantly attenuated VS-induced effective refractory period shortening in the PLA, PV, and LAA and decreased AF inducibility by 92% ( P < 0.001). We conclude that 1) P fibers and M2 receptors are preferentially located in the PLA, suggesting an important role for this region in creation of vagal AF substrate and 2) targeted P blockade in the PLA is feasible and results in attenuation of vagal responses in the entire left atrium and, consequently, a change in AF substrate.
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164
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Abstract
It is hypothesized that the heart possesses a nervous system intrinsic to it that represents the final relay station for the co-ordination of regional cardiac indices. This 'little brain' on the heart is comprised of spatially distributed sensory (afferent), interconnecting (local circuit) and motor (adrenergic and cholinergic efferent) neurones that communicate with others in intrathoracic extracardiac ganglia, all under the tonic influence of central neuronal command and circulating catecholamines. Neurones residing from the level of the heart to the insular cortex form temporally dependent reflexes that control overlapping, spatially determined cardiac indices. The emergent properties that most of its components display depend primarily on sensory transduction of the cardiovascular milieu. It is further hypothesized that the stochastic nature of such neuronal interactions represents a stabilizing feature that matches cardiac output to normal corporal blood flow demands. Thus, with regard to cardiac disease states, one must consider not only cardiac myocyte dysfunction but also the fact that components within this neuroaxis may interact abnormally to alter myocyte function. This review emphasizes the stochastic behaviour displayed by most peripheral cardiac neurones, which appears to be a consequence of their predominant cardiac chemosensory inputs, as well as their complex functional interconnectivity. Despite our limited understanding of the whole, current data indicate that the emergent properties displayed by most neurones comprising the cardiac neuroaxis will have to be taken into consideration when contemplating the targeting of its individual components if predictable, long-term therapeutic benefits are to accrue.
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Affiliation(s)
- J A Armour
- Hôpital du Sacré-Coeur de Montréal, Research Center, 5400 Gouin Boulevard West, Montreal, QC H4J 1C5, Canada.
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165
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Lin J, Scherlag BJ, Zhou J, Lu Z, Patterson E, Jackman WM, Lazzara R, Po SS. Autonomic mechanism to explain complex fractionated atrial electrograms (CFAE). J Cardiovasc Electrophysiol 2007; 18:1197-205. [PMID: 17916143 DOI: 10.1111/j.1540-8167.2007.00976.x] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To simulate complex fractionated atrial electrograms (CFAE) during sustained atrial fibrillation (AF) in experimental animals. BACKGROUND The mechanism(s) underlying CFAE has not been fully elucidated. METHODS Twenty-two dogs were subjected to a right and/or left thoracotomy. A gauze patch soaked with acetylcholine (ACh) was placed on the right atrial appendage (RAA) to induce sustained AF. During AF, varying concentrations of ACh (1, 10, 100 mM) were "painted" on the RA where electrograms showed regular organized activity. In another six dogs, anterior right ganglionated plexi (ARGP) near the sino-atrial node and inferior right GP (IRGP) at the junction of inferior vena cava and atria were sequentially ablated. In five dogs, ACh was injected into ARGP to induce CFAE. RESULTS During sustained AF, local "painting" with ACh 1 mM and 10 mM induced intermittent CFAE in 1 of 11 and 10 of 11 dogs, respectively. With 100 mM ACh, all 11 showed CFAE (two intermittent, nine continuous). In six other dogs, continuous CFAE induced by topical application of 100 mM ACh were markedly attenuated by ARGP + IRGP ablation. In another five of five dogs, ACh injection into ARGP induced a gradient of CFAE with the continuous CFAE always occurring near the ARGP and CFAE also occurring at left pulmonary vein-atrial junctions. During ARGP ablation, AF was terminated in all five dogs immediately after regularization of the rotor-like electrograms or continuous CFAE. CONCLUSIONS This study demonstrates an autonomic basis for CFAE formation, suggesting that graded hyperactive states of the autonomic nervous system (ANS) may induce various types of CFAE observed clinically.
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Affiliation(s)
- Jiaxiong Lin
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai, China
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166
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Oral H, Morady F. Autonomic Innervation, Atrial Electrogram Morphology, and Atrial Fibrillation⁎⁎Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology. J Am Coll Cardiol 2007; 50:1332-4. [PMID: 17903631 DOI: 10.1016/j.jacc.2007.04.098] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2007] [Accepted: 04/10/2007] [Indexed: 11/26/2022]
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167
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Lellouche N, Buch E, Celigoj A, Siegerman C, Cesario D, De Diego C, Mahajan A, Boyle NG, Wiener I, Garfinkel A, Shivkumar K. Functional characterization of atrial electrograms in sinus rhythm delineates sites of parasympathetic innervation in patients with paroxysmal atrial fibrillation. J Am Coll Cardiol 2007; 50:1324-31. [PMID: 17903630 DOI: 10.1016/j.jacc.2007.03.069] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 03/05/2007] [Accepted: 03/14/2007] [Indexed: 11/23/2022]
Abstract
OBJECTIVES This study sought to characterize left atrial (LA) sinus rhythm electrogram (EGM) patterns and their relationship to parasympathetic responses during atrial fibrillation (AF) ablation. BACKGROUND The mechanistic basis of fractionated LA EGMs in patients with paroxysmal AF is not well understood. METHODS We analyzed 1,662 LA ablation sites from 30 patients who underwent catheter ablation for paroxysmal AF. Pre-ablation EGM characteristics (number of deflections, amplitude, and duration) were measured in sinus rhythm. Parasympathetic responses during radiofrequency application (increase of atrial-His interval by > or =10 ms or decrease of sinus rate by > or =20%) were assessed at all sites. We also prospectively studied the effect of adenosine, a pharmacological agent mimicking acetylcholine signaling in myocytes, on LA EGMs. Finally, we performed mathematical simulations of atrial tissue to delineate possible mechanisms of fractionated EGMs in sinus rhythm. RESULTS A specific pattern of pre-ablation sinus rhythm EGM (deflections > or =4, amplitude > or =0.7 mV, and duration > or =40 ms) was strongly associated with parasympathetic responses (sensitivity 72%, specificity 91%). The sites associated with these responses were found to be located mainly in the posterior wall of the LA. Adenosine administration and mathematical simulation of the effect of acetylcholine were able to reproduce a similar EGM pattern. CONCLUSIONS Parasympathetic activation during AF ablation is associated with the presence of pre-ablation high-amplitude fractionated EGMs in sinus rhythm. Local acetylcholine release could potentially explain this phenomenon.
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Affiliation(s)
- Nicolas Lellouche
- UCLA Cardiac Arrhythmia Center, Division of Cardiology, Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1679, USA
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168
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Roka A, Toth E, Szilagyi S, Merkely B. Electrical atrial fibrillation induction affects the characteristics of induced arrhythmia. J Electrocardiol 2007; 41:131-7. [PMID: 17631892 DOI: 10.1016/j.jelectrocard.2007.05.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2007] [Accepted: 05/25/2007] [Indexed: 11/27/2022]
Abstract
Several methods are being used to induce atrial fibrillation (AF) in experimental investigations, which may affect the electrophysiologic parameters of the induced arrhythmia. The aim of our study was the investigation of temporal characteristics of AF during and after electrical induction. Direct current and high-frequency stimulation was used for induction in bipolar biatrial, right and left atrial appendage configurations in 6 dogs. Atrial and ventricular electrical activity was recorded near the bundle of His. Seven statistical parameters were calculated to analyze the temporal characteristics of electrical activity of both chambers. The induction method affected 5 atrial and no ventricular electrophysiologic parameters during stimulation, and the effect disappeared after ceasing induction, during the induced transient or persistent AF. Electrical stimulation affects the properties of the induced arrhythmia during the induction; thus, the investigation of AF is recommended only after ceasing the induction to avoid bias.
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Affiliation(s)
- Attila Roka
- Department of Cardiovascular Surgery, Cardiovascular Centre, Semmelweis University, Budapest, Hungary.
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169
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Yeh YH, Qi X, Shiroshita-Takeshita A, Liu J, Maguy A, Chartier D, Hebert T, Wang Z, Nattel S. Atrial tachycardia induces remodelling of muscarinic receptors and their coupled potassium currents in canine left atrial and pulmonary vein cardiomyocytes. Br J Pharmacol 2007; 152:1021-32. [PMID: 17618308 PMCID: PMC2095106 DOI: 10.1038/sj.bjp.0707376] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND PURPOSE Both parasympathetic tone and atrial tachycardia (AT) remodelling of ion channels play important roles in atrial fibrillation (AF) pathophysiology. Different muscarinic cholinergic receptor (mAChR) subtypes (M2, M3, M4) in atrial cardiomyocytes are coupled to distinct K+-currents (called IKM2, IKM3, IKM4, respectively). Pulmonary veins (PVs) are important in AF and differential cholinergic current responses are a potential underlying mechanism. This study investigated AT-induced remodelling of mAChR subtypes and K+-currents in left-atrial (LA) and PV cardiomyocytes. EXPERIMENTAL APPROACH Receptor expression was assayed by western blot. IKM2, IKM3 and IKM4 were recorded with whole-cell patch-clamp in LA and PV cardiomyocytes of nonpaced control dogs and dogs after 7 days of AT-pacing (400 bpm). KEY RESULTS Current densities of IKM2, IKM3 and IKM4 were significantly reduced by AT-pacing in LA and PV cardiomyocytes. PV cardiomyocyte current-voltage relations were similar to LA for all three cholinergic currents, both in control and AT remodelling. Membrane-protein expression levels corresponding to M2, M3 and M4 subtypes were decreased significantly (by about 50%) after AT pacing. Agonist concentration-response relations for all three currents were unaffected by AT pacing. CONCLUSIONS AND IMPLICATIONS AT downregulated all three mAChR-coupled K+-current subtypes, along with corresponding mAChR protein expression. These changes in cholinergic receptor-coupled function may play a role in AF pathophysiology. Cholinergic receptor-coupled K+-currents in PV cardiomyocytes were similar to those in LA under control and AT-pacing conditions, suggesting that differential cholinergic current properties do not explain the role of PVs in AF.
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MESH Headings
- Animals
- Atrial Fibrillation/metabolism
- Atrial Fibrillation/physiopathology
- Blotting, Western
- Cardiac Pacing, Artificial
- Cells, Cultured
- Disease Models, Animal
- Dogs
- Down-Regulation
- Electrophysiologic Techniques, Cardiac
- Evoked Potentials
- Heart Atria/metabolism
- Heart Atria/pathology
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Patch-Clamp Techniques
- Potassium Channels, Inwardly Rectifying/metabolism
- Pulmonary Veins/metabolism
- Pulmonary Veins/pathology
- Receptors, Muscarinic/biosynthesis
- Receptors, Muscarinic/metabolism
- Tachycardia, Ectopic Atrial/metabolism
- Tachycardia, Ectopic Atrial/physiopathology
- Time Factors
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Affiliation(s)
- Y-H Yeh
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
- First Cardiovascular Division, Department of Medicine, Chang Gung Memorial Hospital, Chang Gung University Tao-Yuan, Taiwan
| | - X Qi
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
| | - A Shiroshita-Takeshita
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
| | - J Liu
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
| | - A Maguy
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
| | - D Chartier
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
| | - T Hebert
- Department of Pharmacology and Therapeutics, McGill University Quebec, Canada
| | - Z Wang
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
| | - S Nattel
- Department of Medicine, Université de Montréal and Research Center, Montreal Heart Institute Quebec, Canada
- Department of Medicine, Université de Montréal Quebec, Canada
- Department of Pharmacology and Therapeutics, McGill University Quebec, Canada
- Author for correspondence:
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170
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Hou Y, Scherlag BJ, Lin J, Zhang Y, Lu Z, Truong K, Patterson E, Lazzara R, Jackman WM, Po SS. Ganglionated plexi modulate extrinsic cardiac autonomic nerve input: effects on sinus rate, atrioventricular conduction, refractoriness, and inducibility of atrial fibrillation. J Am Coll Cardiol 2007; 50:61-8. [PMID: 17601547 DOI: 10.1016/j.jacc.2007.02.066] [Citation(s) in RCA: 268] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 02/12/2007] [Accepted: 02/27/2007] [Indexed: 02/07/2023]
Abstract
OBJECTIVES This study sought to systematically investigate the interactions between the extrinsic and intrinsic cardiac autonomic nervous system (ANS) in modulating electrophysiological properties and atrial fibrillation (AF) initiation. BACKGROUND Systematic ganglionated plexi (GP) ablation to evaluate the extrinsic and intrinsic cardiac ANS relationship has not been detailed. METHODS The following GP were exposed in 28 dogs: anterior right GP (ARGP) near the sinoatrial node, inferior right ganglionated plexi (IRGP) at the junction of the inferior vena cava and atria, and superior left ganglionated plexi (SLGP) near the junction of left superior pulmonary vein and left pulmonary artery. With unilateral vagosympathetic trunk stimulation (0.6 to 8.0 V, 20 Hz, 0.1 ms in duration), sinus rate (SR), and ventricular rate (VR) during AF were compared before and after sequential ablation of SLGP, ARGP, and IRGP. RESULTS The SLGP ablation significantly attenuated the SR and VR slowing responses with right or left vagosympathetic trunk stimulation. Subsequent ARGP ablation produced additional effects on SR slowing but not VR slowing. After SLGP + ARGP ablation, IRGP ablation eliminated VR slowing but did not further attenuate SR slowing with vagosympathetic trunk stimulation. Unilateral right and left vagosympathetic trunk stimulation shortened the effective refractory period and increased AF inducibility of atrium and pulmonary vein near the ARGP and SLGP, respectively. The ARGP ablation eliminated ERP shortening and AF inducibility with right vagosympathetic trunk stimulation, whereas SLGP ablation eliminated ERP shortening but not AF inducibility with left vagosympathetic trunk stimulation. CONCLUSIONS The GP function as the "integration centers" that modulate the autonomic interactions between the extrinsic and intrinsic cardiac ANS. This interaction is substantially more intricate than previously thought.
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Affiliation(s)
- Yinglong Hou
- Department of Cardiology, Shandong Provincial Qianfoshan Hospital, Clinical Medical College of Shandong University, Jinan City, Shandong, China
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171
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Scheinman MM, Keung E. The year in clinical cardiac electrophysiology. J Am Coll Cardiol 2007; 49:2061-9. [PMID: 17512364 DOI: 10.1016/j.jacc.2007.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 02/09/2007] [Accepted: 02/12/2007] [Indexed: 11/16/2022]
Affiliation(s)
- Melvin M Scheinman
- Section of Cardiac Electrophysiology, University of California San Francisco, San Francisco, California 94143, USA.
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172
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Horikawa-Tanami T, Hirao K, Furukawa T, Isobe M. Mechanism of the Conversion of a Pulmonary Vein Tachycardia to Atrial Fibrillation in Normal Canine Hearts: Role of Autonomic Nerve Stimulation. J Cardiovasc Electrophysiol 2007; 18:534-41. [PMID: 17313531 DOI: 10.1111/j.1540-8167.2007.00772.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION The role of the autonomic nervous system in inducing pulmonary vein (PV)-triggered atrial fibrillation (AF) and the termination mechanism of the AF are unknown. The purpose of this study was to elucidate the mechanism of the conversion of a tachycardia within a PV into AF under autonomic stimulation and the termination mechanism of the AF in normal canine hearts. METHODS AND RESULTS In open-chest dogs, the electrophysiologic parameters were measured under vagal stimulation (VS) or an isoproterenol administration. The effects of the VS or isoproterenol on the PV tachycardias (PVTs), which were created by burst pacing from a PV or the application of aconitine onto the PV, were evaluated. Pilsicainide, a Na channel blocker, was administered during the induced AF. VS and isoproterenol shortened the atrial and PV effective refractory periods. In the pacing model, the VS converted the PV rapid activations into sustained AF in 9 of 12 dogs during pacing cycle lengths < or = 120 msec, but the isoproterenol did not cause any sustained AF. In the aconitine model, the VS increased the rate of the aconitine-induced PVTs and transformed them into sustained AF in all 14 dogs, whereas the isoproterenol did not induce AF, and decreased the PVT rate. In all 14 dogs the sustained AF was terminated by pilsicainide, which had suppressive effects on the PVT as well as atria and PV-atrial junction. CONCLUSIONS These findings indicate that the vagal effects affecting the PVT and atria facilitate the onset and maintenance of PV-triggered AF in normal canine hearts.
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Affiliation(s)
- Tomoe Horikawa-Tanami
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, Tokyo, Japan
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173
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Affiliation(s)
- Mark E Josephson
- Division of Cardiology, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02215, USA.
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174
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Hirose M, Ohkubo Y, Takano M, Hamazaki M, Sekido T, Yamada M. Mechanisms of the Preventive Effect of Pilsicainide on Atrial Fibrillation Originating From the Pulmonary Vein. Circ J 2007; 71:1805-14. [DOI: 10.1253/circj.71.1805] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Masamichi Hirose
- Department of Molecular Pharmacology, Shinshu University School of Medicine
| | - Yosuke Ohkubo
- Department of Molecular Pharmacology, Shinshu University School of Medicine
| | - Michitoshi Takano
- Department of Molecular Pharmacology, Shinshu University School of Medicine
| | - Mikihisa Hamazaki
- Department of Molecular Pharmacology, Shinshu University School of Medicine
| | - Takashi Sekido
- Department of Molecular Pharmacology, Shinshu University School of Medicine
| | - Mitsuhiko Yamada
- Department of Molecular Pharmacology, Shinshu University School of Medicine
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175
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Zhou J, Scherlag BJ, Edwards J, Jackman WM, Lazzara R, Po SS. Gradients of Atrial Refractoriness and Inducibility of Atrial Fibrillation due to Stimulation of Ganglionated Plexi. J Cardiovasc Electrophysiol 2007; 18:83-90. [PMID: 17229305 DOI: 10.1111/j.1540-8167.2006.00679.x] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
INTRODUCTION The mechanism(s) whereby atrial ectopy induces atrial fibrillation (AF) is still poorly understood. METHODS AND RESULTS In 12 dogs, we determined the refractory period (RP) along the right atrium (RA) and right superior pulmonary vein (RSPV), and AF inducibility with and without concurrent stimulation of the anterior right ganglionated plexi (ARGP) at the base of the RSPV. Multielectrode catheters were attached to the RSPV and RA with the distal electrodes close to ARGP. The RP and window of vulnerability (WOV), i.e., the longest S1-S2 minus the shortest S1-S2 at which AF was induced, were measured before and during incremental levels of ARGP stimulation. Mapping of the onset of AF was performed using the EnSite mapping system (St. Jude Medical, St. Paul, MN, USA) positioned in the RA. A single premature depolarization (PD) from the RSPV that did not induce AF without ARGP stimulation could do so with ARGP stimulation. The onset of AF consistently arose at the myocardium subtending the ARGP. With GP stimulation, the average WOV at the RSPV-atrial junction was significantly wider than at the RA appendage (65 +/- 27 vs. 8 +/- 17 msec, P < 0.05) or further along the RSPV sleeve (48 +/- 39 vs. 10 +/- 20 msec, P < 0.05). Even without GP stimulation, high intensity (10-20 mA) premature stimuli delivered at the RA appendage induced AF, originating from atrial tissue subtending the ARGP, presumably due to axonal conduction that activated the ARGP. CONCLUSION GP stimulation, subthreshold for atrial excitation, converts isolated PDs into AF-inducing PDs, suggesting that autonomic tone may play a critical role in the initiation of paroxysmal AF.
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Affiliation(s)
- Jing Zhou
- Department of Cardiology, First Hospital of Peking University, Beijing, China
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176
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Hou Y, Scherlag BJ, Lin J, Zhou J, Song J, Zhang Y, Patterson E, Lazzara R, Jackman WM, Po SS. Interactive atrial neural network: Determining the connections between ganglionated plexi. Heart Rhythm 2006; 4:56-63. [PMID: 17198991 DOI: 10.1016/j.hrthm.2006.09.020] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Accepted: 09/13/2006] [Indexed: 11/23/2022]
Abstract
BACKGROUND The electrophysiologic functions of the intrinsic cardiac autonomic nervous system (ANS) are not well understood. OBJECTIVES The purpose of this study was to investigate the functional interactions between ganglionated plexi within the intrinsic cardiac ANS. METHODS The hearts of 21 dogs were exposed via right and/or left thoracotomy to expose the (1) anterior right ganglionated plexi near the caudal end of the sinoatrial node, (2) inferior right ganglionated plexi at the junction of inferior vena cava and atria, and (3) superior left ganglionated plexi near the junction of left superior pulmonary vein and left pulmonary artery. Ganglionated plexi were stimulated at 0.6 to 8.0 V (square waves, 20 Hz, 0.1-ms duration). Sinus rate, AH interval during atrial pacing, and ventricular rate during atrial fibrillation were compared before and after ganglionated plexi stimulation and after their ablation. RESULTS Anterior right ganglionated plexi stimulation induced significant AH prolongation and slowing of ventricular rate and sinus rate. When inferior right ganglionated plexi was ablated, slowing of sinus rate by anterior right ganglionated plexi stimulation was unaltered, but inhibition of AV conduction was eliminated. Superior left ganglionated plexi stimulation induced similar effects on sinus and AV nodal function, and sinus rate slowing was markedly attenuated by anterior right ganglionated plexi ablation. Ablation of both anterior right ganglionated plexi and inferior right ganglionated plexi eliminated AV conduction inhibition but not sinus rate slowing by superior left ganglionated plexi stimulation. CONCLUSION This study provides functional evidence for the interconnections between ganglionated plexi to modulate sinus and AV nodal function, supporting clinical evidence that interconnections within the intrinsic cardiac ANS are critical elements in identifying the targets for atrial fibrillation ablation.
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Affiliation(s)
- Yinglong Hou
- Department of Cardiology, Shandong Provincial Qianfoshan Hospital, Clinical Medical College of Shandong University, Jinan City, Shandong, China
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Po SS. Critical review and commentary by Drs. Allessie and Schotten. Heart Rhythm 2006; 3:990-1; author reply 991. [PMID: 16876757 DOI: 10.1016/j.hrthm.2006.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Indexed: 11/19/2022]
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