Vankawala Viren, Markabawi Bashar, Dainiak Sara, Werner Morgan, Hager W David, Farrel William, Katz Arnold M, Silverman David I
Cardiology Division, Department of Medicine, University of Connecticut School of Medicine, Farmington, CT 06030-1305, USA.
Am Heart J. 2002 May;143(5):827-32. doi: 10.1067/mhj.2002.121272.
Our purpose was to measure the effect of ventricular pacing in patients with atrial fibrillation (AF) on stroke volume and cardiac output.
Unceasing variation in cycle length in AF decreases stroke volume and cardiac output. Because ventricular-inhibited pacing after atrioventricular node ablation has been reported to improve left ventricular performance, we tested the hypothesis that overdrive pacing would produce a similar benefit by regularizing cycle length.
We studied 18 patients with chronic AF and permanent pacemakers. The aortic time velocity integral (TVI) was measured with continuous-wave Doppler and was used as a surrogate measure of stroke volume (stroke volume = TVI x aortic valve area, and aortic valve area is constant whether in AF or during pacing). For each patient, the linear relation between preceding cycle length and TVI in AF was used to estimate relative stroke volume (TVI compared within each patient) at a preceding cycle length of 666 ms in AF, and a similar comparison between AF and pacing was made at the minimum allowable pacing rate. Relative stroke volume in AF was then compared with relative stroke volume at both the fixed cycle (666 ms) and the minimum allowable rate. During pacing at 666 ms, relative stroke volume increased significantly by 18% (t = 2.8, P =.048), but there was no difference in cardiac output during pacing at the minimum possible rate and the corresponding preceding cycle length in AF.
Our data suggest that regularization of ventricular rhythm by overdrive pacing in patients with AF only improves stroke volume (and by extension, cardiac output) at pacing rates at the outer limit of and above the normal physiologic range.
我们的目的是测量心房颤动（AF）患者心室起搏对每搏输出量和心输出量的影响。
AF 时周期长度的不断变化会降低每搏输出量和心输出量。由于据报道房室结消融后心室抑制起搏可改善左心室功能，我们检验了超速起搏通过使周期长度规律化会产生类似益处的假设。
我们研究了 18 例慢性 AF 且植入永久性起搏器的患者。用连续波多普勒测量主动脉时间速度积分（TVI），并将其用作每搏输出量的替代指标（每搏输出量 = TVI×主动脉瓣面积，且无论处于 AF 还是起搏状态，主动脉瓣面积恒定）。对于每位患者，利用 AF 中前一周期长度与 TVI 之间的线性关系来估计 AF 中前一周期长度为 666 毫秒时的相对每搏输出量（在每位患者内比较 TVI），并在最小允许起搏频率下对 AF 与起搏进行类似比较。然后将 AF 中的相对每搏输出量与固定周期（666 毫秒）和最小允许频率下的相对每搏输出量进行比较。在 666 毫秒起搏时，相对每搏输出量显著增加 18%（t = 2.8，P = 0.048），但在最小可能频率起搏时的心输出量与 AF 中相应的前一周期长度时的心输出量无差异。
我们的数据表明，AF 患者通过超速起搏使心室节律规律化仅在起搏频率达到并高于正常生理范围上限时才会改善每搏输出量（进而改善心输出量）。
