摘要：The relationship between the atrioventricular (AV) conduction ratio and systolic blood pressure or right atrial pressure during atrial pacing was investigated before and after phamacological autonomic nervous blockade (PAB) in horses. The increase in the pacing rate decreased the AV conduction ratio. Systolic blood pressure increased when the AV conduction ratio became low, but the relevancy of the both stopped being recognized after PAB. Also right atrial pressure decreased with a decrease in the AV conduction ratio irrespective of the presence of PAB. These findings indicate that the onset mechanism of dropped beats involves an interaction among atrial rate, AV conduction, autonomic nervous system, and hemodynamics in horses with a second degree AV block.
