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Figure 1 Variations in Regional ERP Response With Miscellaneous Autonomic Maneuvers

(A) Comparison of vagal stimulation (VS) versus baseline indicates parasympathetic responsiveness in the resting state; this was most pronounced in the pulmonary vein (PV). Comparison of propranolol (P) + atropine (ATR) versus baseline indicates resting vagal tone, which was greatest in the left atrial appendage (LAA). (B) With P + VS, more pronounced effective refractory period (ERP) shortening was noted in the PV, posterior left atrium (PLA), and LAA as compared with ERP shortening with VS alone. See text for discussion. *p < 0.05.