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一例房室传导系统纵向分离的长期室上性阵速患者,在心房快速起搏时,首先出现2∶1房室阻滞,突然变为3∶2文氏周期,使 A-H 明显延长,引起交替性文氏周期,直到连续两个激动被阻滞。此后 A-H 缩短,恢复2∶1房室传导。另外,在 A-H 延长时,或激动下传后突然关掉起搏器,均可见到心房回波。上述现象可以重复,但交替性文氏周期无连续性,不能用目前双水平阻滞区的机理解释,作者认为系隐匿性折返所致。在2∶1房室阻滞时,A-H 的长度未达到引起折返的临界值。到3∶2文氏周期时,第2个下传滚动的 A-H 超过临界值,就在房室交界区的近端逆行折返。但折返的联律间期
A case of long-term supraventricular tachycardia in patients with atrioventricular conduction system longitudinally separated showed a 2: 1 atrioventricular block at the onset of rapid atrial pacing, suddenly changing to a 3: 2 cycle and significantly prolonging AH, causing alternation Sexual Wen’s cycle until two consecutive excitations are blocked. After A-H shortened, restore 2: 1 atrioventricular conduction. In addition, the A-H extended, or excited off after a sudden switch off the pacemaker, can see the atrial echo. The above phenomenon can be repeated, but there is no continuity of Alternating Periodicity and can not be explained by the current mechanism of double horizontal block. The author believes that this phenomenon is due to occult reentry. At 2: 1 atrioventricular block, the length of A-H did not reach the threshold causing reentry. By 3 to 2 Wen’s cycle, the 2nd roll-off A-H exceeded the cut-off value and was retrograde retrograde at the proximal end of the atrioventricular junction. But the reincarnation of the inter-law period