Gang E S, Peter T, Nalos P C, Meesmann M, Karagueuzian H S, Mandel W J, Oseran D S, Myers M R
Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California 90048.
J Am Coll Cardiol. 1988 Mar;11(3):515-21. doi: 10.1016/0735-1097(88)91525-2.
This study investigated the possibility of terminating reciprocating atrioventricular (AV) tachycardia using subthreshold atrial pacing. Ten patients with a left-sided accessory pathway and sustained AV tachycardia underwent subthreshold atrial pacing from the coronary sinus site closest to insertion of the accessory pathway. In seven of these patients, the tachycardia could be reliably terminated with subthreshold atrial overdrive pacing. When pacing at a cycle length of 80 +/- 23% of the tachycardia cycle length, the minimal subthreshold current that was effective in tachycardia termination was 64 +/- 14% of threshold current and the maximal ineffective current was 49 +/- 17% of threshold (p less than 0.05). In all cases, the tachycardia was terminated by one or two instances of atrial capture that resulted in a premature atrial impulse (20 +/- 4% advancement of the atrial cycle) that blocked the AV node limb of the tachycardia. Anterograde conduction over the accessory pathway never occurred, either during the tachycardia or during subthreshold pacing after a return to normal sinus rhythm. No instances of atrial fibrillation were provoked by subthreshold pacing. Possible explanations for the intermittent atrial capture with critically placed subthreshold impulses include supernormal atrial conduction or summation of impulses at the atrial insertion site of the accessory pathway. It is concluded that subthreshold pacing is effective in selected patients with AV tachycardia due to an accessory pathway. Furthermore, because neither atrial fibrillation nor anterograde conduction over the accessory pathway is seen with subthreshold pacing, this modality may hold significant promise for permanent antitachycardia pacing in these patients.
本研究探讨了使用阈下心房起搏终止往复性房室（AV）心动过速的可能性。10例左侧旁路并持续性AV心动过速患者，从最靠近旁路插入处的冠状窦部位进行阈下心房起搏。其中7例患者，阈下心房超速起搏可可靠地终止心动过速。当起搏周期长度为心动过速周期长度的80±23%时，能有效终止心动过速的最小阈下电流为阈电流的64±14%，最大无效电流为阈电流的49±17%（P<0.05）。在所有病例中，心动过速通过一两次心房夺获终止，导致房性早搏（心房周期提前20±4%），阻断了心动过速的房室结支。在心动过速期间或恢复正常窦性心律后的阈下起搏期间，旁路均未发生前传。阈下起搏未诱发房颤。阈下冲动临界放置时出现间歇性心房夺获的可能解释包括超常心房传导或旁路心房插入部位的冲动总和。结论是，阈下起搏对某些因旁路导致AV心动过速的患者有效。此外，由于阈下起搏未观察到房颤和旁路前传，这种方式可能对这些患者的永久性抗心动过速起搏具有重要前景。
