Hassan Sohail A, Oral Hakan, Scharf Christoph, Chugh Aman, Pelosi Frank, Knight Bradley P, Strickberger S Adam, Morady Fred
Division of Cardiology, Department of Internal Medicine, University of Michigan Medical Center, 1500 East Medical Center Drive, Ann Arbor, MI 49109-0022, USA.
J Am Coll Cardiol. 2003 Feb 5;41(3):446-51. doi: 10.1016/s0735-1097(02)02771-7.
The purpose of this study was to determine whether verapamil has rate-dependent effects on the atrial effective refractory period (AERP).
Block of calcium current (I(Ca)) and rapid component of the delayed rectifier potassium current (I(Kr)) by verapamil is frequency-dependent. This may result in variable effects of verapamil on the AERP, depending on the rate.
The subjects of this study were 30 adults with a mean age of 45 +/- 13 years who did not have structural heart disease. In 20 subjects, the AERP was measured at basic drive cycle lengths (BDCLs) of 650 to 250 ms, in 50 ms decrements, before and after infusion of 0.1 mg/kg verapamil. The effective refractory periods (ERPs) were measured in the setting of autonomic blockade in 10 subjects and without autonomic blockade in 10 subjects. Ten subjects served as a control group and received a saline infusion instead of verapamil.
Verapamil significantly prolonged the AERP at BDCLs of 650 to 500 ms (p < 0.01 or p < 0.05) and significantly shortened the ERP at BDCLs of 300 and 250 ms (p < 0.01). In the control group, there were no significant differences between the baseline and post-saline measurements of ERP.
Verapamil prolongs AERP at slow rates and shortens AERP at rapid rates. These findings are consistent with a predominant effect on I(Ca) at rapid rates and a predominant effect on I(Kr) at slow rates.
本研究旨在确定维拉帕米对心房有效不应期（AERP）是否具有频率依赖性效应。
维拉帕米对钙电流（I(Ca)）和延迟整流钾电流快速成分（I(Kr)）的阻滞具有频率依赖性。这可能导致维拉帕米对AERP产生不同的影响，具体取决于心率。
本研究的受试者为30名平均年龄45±13岁、无结构性心脏病的成年人。在20名受试者中，于静脉输注0.1mg/kg维拉帕米前后，以50ms递减的方式，在650至250ms的基础驱动周期长度（BDCL）下测量AERP。在10名受试者的自主神经阻滞状态下以及10名未进行自主神经阻滞的受试者中测量有效不应期（ERP）。10名受试者作为对照组，接受生理盐水输注而非维拉帕米。
维拉帕米显著延长了BDCL为650至500ms时的AERP（p<0.01或p<0.05），并显著缩短了BDCL为300和250ms时的ERP（p<0.01）。在对照组中，ERP的基线测量值与输注生理盐水后的测量值之间无显著差异。
维拉帕米在心率较慢时延长AERP，在心率较快时缩短AERP。这些发现与快速心率时对I(Ca)的主要作用以及慢速心率时对I(Kr)的主要作用一致。
