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异位自主性心动过速是指由于某种原因使心脏异位起搏点的自律性增高,并超过窦性频率时所产生的一种心律失常。由于此类心律失常的异位起搏点不具有保护性的“传入阻滞”,当窦性频率快于异位频率时,心搏由窦房结控制,反之则由异位起搏点控制。 1产生原理 1.1正常心脏内除工作的心房肌、心室肌不呈现有自律性外,其余组织中均有自律细胞形成起搏点,各起搏点自律性各不相同,但通常只有一个自律性最高的起搏点占据优势地位决定整个心脏的兴奋节律。正常情况下,窦房结细胞位相4的坡度最陡,达到阈电位的速度最快、自律性最高,每min能兴奋70～80次。其他起搏点如房室交界区每min兴奋50～60次,His束35～45次,浦肯野纤维30～40次。这些起搏点的自律细胞由于舒张期
Ectopic autonocardial tachycardia is due to some reason to eutopic pacemaker echocardiography increased self-discipline, and more than the sinus frequency of arrhythmias produced. Because of such arrhythmia ectopic pacemaker does not have a protective “afferent block,” when the sinus frequency is faster than the ectopic frequency, the heart be controlled by the sinus node, and vice versa by the ectopic pacemaker control. 1 Principle 1.1 The normal heart In addition to the work of the atrial and ventricular muscles do not appear to have self-discipline, the rest of the organization have self-paced cells to form pacemaker, each pacemaker self-discipline vary, but usually only a self-discipline The dominance of the highest pacemaker determines the excitement rhythm throughout the heart. Under normal circumstances, the sinoatrial node phase 4 of the steepest gradient to reach the threshold potential of the fastest, highest self-regulation, every min can be excited 70 to 80 times. Other pacemaker points such as atrioventricular junction area excited 50 ~ 60 times per min, His bundle 35 ~ 45 times, Purkinje fiber 30 ~ 40 times. Autonomic cells at these pace points are due to diastolic phase