Vulliemin P, Del Bufalo A, Schlaepfer J, Fromer M, Kappenberger L
Department of Internal Medicine, University Hospital, Lausanne, Switzerland.
Pacing Clin Electrophysiol. 1994 Aug;17(8):1391-8. doi: 10.1111/j.1540-8159.1994.tb02458.x.
Assuming that type I atrial flutter is a macroreentrant circuit, its cycle length should vary with the atrial dimensions. In order to test this hypothesis, flutter cycle length was measured while inducing atrial volume and pressure changes by postural and pharmacological means in seven patients undergoing a therapeutic programmed stimulation for type I atrial flutter conversion. Right atrial volume was estimated from B-mode echocardiography data. Basal values were compared with those obtained during inspiration, expiration, Valsalva maneuver, negative tilt (head down), and positive tilt (head up) with 0.8-1.6 mg p.o. nitroglycerin. The right atrial size increased slightly from 17.8 to 18.3 cm2 (P = 0.04) during the pressure load induced by negative tilt (+3 mmHg), with a corresponding lengthening of the flutter cycle length from 228 to 233 msec (P = 0.02). Similarly, pressure unloading of -2 mmHg by positive tilting and nitrates was accompanied by a decrease in right atrial size to 16.6 cm2 (P = 0.04), with a corresponding decrease in cycle length from 228 to 219 msec (P = 0.03). Respiratory maneuver yielded similar results with an inspiratory cycle lengthening, expiratory shortening, and further shortening during Valsalva maneuver. These experiments demonstrate a direct relation between cycle length and atrial volume in human type I atrial flutter. They underline the importance of the right heart preload and atrial size for the electrophysiological characteristics of type I atrial flutter. Beside its fundamental interest, this finding is important for the understanding of the mechanism of maintenance and therapeutic responses of this common arrhythmia.
假设I型心房扑动是一种大折返环，其周期长度应随心房大小而变化。为了验证这一假设，对7例因I型心房扑动转复而接受治疗性程控刺激的患者，通过体位和药物方法改变心房容积和压力时测量扑动周期长度。根据B型超声心动图数据估算右心房容积。将基础值与吸气、呼气、瓦尔萨尔瓦动作、头低位（头部向下）和头高位（头部向上）时以及口服0.8 - 1.6 mg硝酸甘油时获得的值进行比较。在头低位（+3 mmHg）引起的压力负荷期间，右心房大小从17.8 cm² 略微增加至18.3 cm² （P = 0.04），同时扑动周期长度相应地从228毫秒延长至233毫秒（P = 0.02）。同样，头高位和使用硝酸盐使压力降低2 mmHg时，右心房大小减小至16.6 cm² （P = 0.04），同时周期长度从228毫秒相应地缩短至219毫秒（P = 0.03）。呼吸动作产生了类似的结果，吸气时周期延长，呼气时缩短，瓦尔萨尔瓦动作时进一步缩短。这些实验证明了人类I型心房扑动的周期长度与心房容积之间存在直接关系。它们强调了右心前负荷和心房大小对I型心房扑动电生理特征的重要性。除了其基本的研究意义外，这一发现对于理解这种常见心律失常的维持机制和治疗反应也很重要。
