Changes in pacing threshold and R wave amplitude after transvenous catheter countershock

Transvenous electrode catheter countershock in patients with recurrent ventricular tachyarrhythmias may be followed by transient bradycardia and require temporary pacing with a catheter. The serial changes in R wave amplitude and stimulation threshold after catheter countershock in 11 halothane-anesthetized open chest dogs ranging in weight from 11.8 to 24 kg were studied. Ventricular fibrillation was electrically induced and followed by catheter defibrillation using nonsynchronized trapezoidal waveform (65% tilt) current discharge in incremental doses (5 to 50 J). Significant decreases in bipolar R wave amplitude (8.3 +/- 1 versus 2 +/- 0.2 mV, p less than 0.001) and increases in stimulation threshold (1 +/- 0.1 versus 2.3 +/- 0.4 V, p less than 0.001) were observed using the countershock catheter 15 seconds after countershock; these changes persisted for up to 10 minutes. To determine whether these changes were localized to the defibrillating catheter and whether they were species-specific, a second electrode catheter was positioned in the right ventricle distant from the countershock catheter in five pigs. Increases in stimulation threshold were observed only at the countershock catheter, suggesting that changes were secondary to local changes at the catheter-myocardium interface. No significant change in R wave amplitude or stimulation threshold was observed at the countershock catheter in three pigs given transthoracic shocks (60 to 250 J). It is concluded that current discharge through the countershock catheter results in a significant temporary reduction in R wave amplitude and an increase in pacing threshold. This may make pacing through the countershock catheter unreliable after shock delivery.     

Correlation between changes in R wave amplitude and left ventricular volume induced by rapid atrial pacing

To examine the Brody effect in humans, we studied 15 patients by means of coronary sinus pacing. We measured left ventricular (LV) volumes from the cardiac output (measured by the thermodilution technique) and LV ejection fraction (measured by radionuclide ventriculography). Pulmonary blood volume was determined by means of cardiac output and mean pulmonary transit time. In six patients, pacing was performed at two different rates, resulting in 21 pacing measurements. The heart rate increased with pacing from 73 ± 11 to 119 ± 19 bpm (mean ± standard deviation, p < 0.001). The end-diastolic volume (EDV) and the end-systolic volume (ESV) decreased with pacing (p < 0.001 each). The R wave amplitude decreased with pacing (1.44 ± 0.63 mV control vs 1.32 ± 0.58 mV with pacing; p < 0.01). R wave amplitude decreased in 19 of the 21 pacing studies (90%); EDV and ESV decreased in all 21 pacing studies, and pulmonary blood volume decreased in 14 of the 15 pacing studies (93%) performed in 11 patients. There was a significant correlation between the percentage of change in R wave amplitude with the percentage of change in EDV (r = 0.54, p < 0.01) and with the percentage of change in ESV (r = 0.54, p < 0.01). These results, therefore, validate Brody's hypothesis and indicate that changes in LV volumes affect the R wave amplitude.     

Role of a catheter lead system for transvenous countershock and pacing during electrophysiologic tests: an assessment of the usefulness of catheter shocks for terminating ventricular tachyarrhythmias

The practicality and safety of using a single catheter system for transvenous countershock, programmed stimulation and ventricular pacing during electrophysiologic tests were evaluated in 13 patients with inducible sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). The efficacy and patient toleration of transvenous countershock were compared with other methods of arrhythmia termination. The same lead was used for programmed stimulation at the right ventricular apex and for VT termination by pacing methods during serial testing (20 ± 15 days [mean ± standard deviation]). Synchronized countershock using energies that patients found tolerable (0.01 to 5 J) terminated 31 of 50 episodes (62%) of induced VT. Episodes of VT cardioverted with these low energies were distinguished from other episodes by a longer cycle length (352 ± 62 ms versus 297 ± 50 ms, p < 0.004). Among paired episodes of VT matched for patient, date of induction, morphologic characteristics, cycle length and drugs administered, pacing methods (single extrastimuli and bursts of rapid pacing) were just as effective as low-energy countershock for VT termination (25 of 25 versus 21 of 25, difference not significant). Transvenous countershock was uniformly effective for termination of ventricular flutter and VF when sufficient energy was used (range 5 to 30 J, mean 20.4 ± 7.7). This required interfacing leads to a defibrillation unit. VT acceleration occurred during 7 of 50 synchronized low-energy cardioversion attempts (14%). There was no evidence of myocardial injury as a result of shocks as high as 30 J, but patients required increasing sedation when energy exceeded 0.5 J.Thus, a single catheter system can be used for programmed stimulation, ventricular pacing and countershock during electrophysiologic tests. Low-energy countershock (0.01 to 5 J) is no more effective than pacing methods for VT termination and is tolerated less well. The most practical use of this catheter system, including any implantable unit, may be for slightly higher energy (5 to 30 J) countershock termination of repeated episodes of very rapid VT or VF, in which pacing techniques are ineffective. This method may be safer and less traumatic than conventional transthoracic countershock.     

双房单室三腔起搏器治疗病窦综合征并快速房性心律失常

观察双心房、单心室三腔起搏器治疗病窦综合征合并阵发性房性快速心律失常患者的疗效。三根电极导线分别置入冠状静脉窦内、右心耳和右室心尖部行三腔起搏。冠状窦电极导线与右心房电极导线通过一个Y型转接器构成心房部分。结果 :10例患者 ,9例经左锁骨下静脉径路置入导线 ,1例因存在残存左上腔静脉 ,从右锁骨下静脉置入。 10例中 9例冠状窦电极导线置于冠状静脉窦中部、1例置于冠状静脉窦远端。冠状窦起搏阈值为 1.0 6±0 .2 0V、起搏阻抗 6 11± 115 .8Ω、P波振幅为 4.0 7± 0 .88mV ;右室电极起搏阈值为 0 .5 3± 0 .12V、起搏阻抗 6 70 .3±191.7Ω、R波振幅为 9.6 6± 1.87mV。随访 5～ 2 4个月有 9例起搏器呈DDD工作方式 ,1例呈AAT工作方式。起搏和感知功能良好。 10例中 8例快速性房性心律失常完全控制 ,2例发作次数减少 ,持续时间明显缩短。无一例出现并发症。结论 :三腔起搏器技术安全、可靠。适合于缓慢型心律失常合并阵发性房性快速性心律失常     

Kappa 700型双腔起搏器的临床随访

观察具有自动夺获功能的双腔起搏器 (Kappa 70 0 )置入后参数的变化和安全性情况。随访 1 3例置入Kappa70 0型起搏器患者 ,观察术中、术后 1周及术后 1 ,3,6个月心室起搏阈值、输出电压、输出脉宽、电极阻抗、R波振幅的变化 ,了解起搏器的工作情况。术后测得的起搏阈值较术中明显升高 ( 0 .71± 0 .2 3Vvs 0 .39± 0 .0 6V ,P <0 .0 5 ) ,术后不同时间测得的起搏阈值无明显差异。R波振幅术中、术后无明显差异。术后阻抗较术中明显降低 ( 62 5 .7± 1 2 3.0Ωvs 894.3± 1 90 .3Ω ,P <0 .0 5 ) ,术后 1个月后的阻抗基本稳定。起搏器自动夺获功能打开后 ,平均输出电压为 0 .96～ 1 .1 6V ,平均输出脉宽 0 .32～ 0 .34ms,平均心房感知灵敏度 0 .71～ 0 .83mV ,心室感知灵敏度 3.82～3.91mV。随访期间起搏、感知功能正常 ,无误感知现象。具有自动夺获功能的双腔起搏器输出电压低 ,安全可靠。     

Low-Energy Transvenous Cardioversion of Atrial Fibrillation Using a Single Atrial Lead System

Atrial Cardioversion Using a Single Atrial Lead System. Introduction: Clinical studies have shown that electrical conversion of atrial fibrillation (AF) is feasible with transvenous catheter electrodes at low energies. We developed a single atrial lead system that allows atrial pacing, sensing, and defibrillation to improve and facilitate this new therapeutic option. Methods and Results: The lead consists of a tripolar sensing, pacing, and defibrillation system. Two defibrillation coil electrodes are positioned on a stylet-guided lead. A ring electrode located between the two coils serves as the cathode for atrial sensing and pacing. We used this lead to cardiovert patients with acute or chronic AE. The distal coil was positioned in the coronary sinus, and the proximal coil and the ring electrode in the right atrium. R wave synchronized biphasic shocks were delivered between the two coils. Atrial signal detection and pacing were performed using the proximal coil and the ring electrode. Eight patients with acute AF (38 ± 9 min) and eight patients with chronic AF (6.6 ± 5 months) were included. The fluoroscopy time for lead placement was 3.5 ± 4.3 minutes. The atrial defibrillation threshold was 2.0 ± 1.4 J for patients with acute AE and 9.2 ± 5.9 J for patients with chronic AF (P < 0.01). The signal amplitude detected was 1.7 ± 1.1 mV during AF and 4.0 ± 2.9 mV after restoration of sinus rhythm (P < 0.001). Atrial pacing was feasible at a threshold of 4.4 ± 3.3 V (0.5-msec pulse width). Conclusions: Atrial signal detection, atrial pacing, and low-energy atrial defibrillation using this single atrial lead system is feasible in various clinical settings. Tbis system might lead to a simpler, less invasive approach for internal atrial cardioversion.     

单根电极VDD起搏器的初步应用（附七例报告）

自１９９４年１～１０月共为７例（完全性房室传导阻滞６例、高度房室传导阻滞１例）病人应用了单电极ＶＤＤ起搏器。术后随诊３～１２（平均６．５±２．５）个月，动态心电图监测全部达到心房同步起搏的目的，其中１例有个别间断性Ｐ波感知差而自动转为ＶＶＩ起搏，但总的Ｐ波感知率在９８％以上。如植入病例经严格选择（窦房功能正常的房室传导阻滞），单电极ＶＤＤ起搏可代替双腔ＤＤＤ起搏。     

新型食管心脏调搏电极导管的研制与应用

研制一种新型食管心脏调搏电极导管，以进一步降低食管心脏调搏术的起搏阈值，减轻受检者痛苦，便于开展食管心室调搏术。第一阶段：设制出各型食管电极导管12种，每种导管随机测试病人20例，共240例，以揭示起搏阈值与电极宽度、电极长度和电极间距三者关系。第二阶段：据此，研制2种新型食管心脏调谐电极导管，每种导管随机测试病人40例，共80例。结果发现食管心脏调搏电极导管的最适电极宽度为5～6mm、电极长度为10mm和电极间距为35mm，按此规格研制的JD－2－9－35－10－5型和JD－2－9－35－10－6型新型食管心脏调搏电极导管，心房调掉时起搏阈值分别为12．1±3．2（5．0～17．5）V和10．3±2．6（5．0～15．0）V，心室调搏时起搏阈值分别为24．0±5．5（15．0～35．0）V和20．3±4．9（12．5～30．0）V，心室调搏的成功率分别为85％（34／40）和95％（38／40）。结论：与目前国内常用的食管电极导管比较，该导管具有起搏阈值低、病人痛苦少、适应性广、性能可靠和操作方便等优点。     

食管导电球囊电极导管的研制与应用

因普通金属环电极在食管内较难定位心室部位 ,而且起搏阈值高 ,检查时病人痛苦较大 ,限制了经食管心室起搏的临床应用。为探讨一种低阈值、简单易行的经食管心室起搏方法 ,笔者自行设计研制了一种经食管心室起搏导电球囊电极导管。该导电球囊电极经抽、充气可使球囊瘪缩或膨胀 ,以利于球囊导管自鼻孔插入或拔出。导电球囊经充气后膨胀 ,其导电面积较金属环电极增大 5 0倍 ,这有利于降低起搏阈值。笔者对 5 8例受检者同时应用普通金属环电极导管与导电球囊电极导管进行经食管心室起搏。结果 :应用金属环电极导管只有 41例完成检查 ,而导电球囊电极导管有 5 6例顺利完成经食管心室起搏检查 ,其成功率分别为 68.3%与 96.5 % ,心室起搏阈值分别为 38.67± 1 .2 8V和 2 5 .2 7± 3.69V ;两者相比 ,差异有显著性 (P均 <0 .0 5 )。结论 :该导电球囊具有导电面积大 ,与食管接触良好 ,易于在食管内定位起搏心室。与普通金属环电极导管比较 ,具有起搏阈值低、成功率高 ,病人痛苦小等优点 ,值得临床推广应用     

Premier起搏器临床应用的初步体会

对12例安置 Premier 起搏器的病人进行观察。安置时起搏阈值0.44±0.1 V、阻抗506±98 Ω(5 V 起搏时)、R波振幅8.58±6.3 mV。随访2～8个月,测得在0.8 V 起搏时的脉宽阈值为0.18～0.24 ms,显示其有良好的低阈值性能。程控取1.6 V、0.3～0.36 ms 就可保证安全有效的起搏。初步体会该起搏器性能良好,配合激素电极可节省耗电量和延长起搏器寿命。预计其寿命可超过16年。     

Variation in the evoked ventricular potentials after the implantation of an endocardiac catheter; the correlation with stimulation thresholds]

BACKGROUND: The drop in T wave amplitude of the ventricular pace-evoked response (VER) is a well-recognized and reliable mean of detecting localized conditions of myocardial hypoxia. In patients who undergo pacemaker implantation, the post-implant change at the electrode-tissue interface consists of an early inflammatory reaction. The aim of this study was to establish whether the extent of the inflammatory reaction following an endocardial lead can be assessed by the changes in the T wave amplitude of VER. METHODS: Modifications in VER amplitude and the correlation between these changes and pacing threshold time-course were evaluated in 30 patients receiving an endocardial catheter. Telemetered endocardial recordings of T wave amplitude and pacing thresholds were measured at the time of implant and after 1, 2, 3, 7, 14 and 30 days. RESULTS: A biphasic time-course was observed for T wave, characterized by reduction in amplitude of 48% (p < 0.005) from baseline at day 3 and subsequent increment up to 84% (p = ns) of the baseline value at day 30. By using a linear regression analysis, a significant correlation between T wave changes and increment in pacing threshold was found (r = 0.81; p < 0.002). A higher pacing threshold increment was observed in patients having a decrease in VER amplitude > or = 1 mV at 3rd in comparison with patients with a decrease in VER amplitude < 1 mV (1.1 +/- 0.4 vs 0.2 +/- 0.2 V; p < 0.001). CONCLUSIONS: VER recordings during the first days after endocardial lead implantation may be a valuable means of assessing the extent of the inflammatory reaction developing at the electrode-tissue interface. This method may be useful for early identification of patients at risk of increases in pacing threshold and for evaluation of the biocompatibility of different leads.     

右室永久起搏可行的后备电极放置部位——右室流出道

为探讨冠心病心肌纤维化、合并糖尿病或恶性肿瘤放射治疗后出现房室阻滞的患者右室永久起搏可行的后备电极放置部位，对３例电极脱位至右室流出道、９例因上述疾病主动将电极置入右室流出道的患者进行了起搏阈值测定及随访。结果：１２例患者右室流出道起搏阈值（电压：０．８６±０．１０Ｖ，脉宽：０．３±０．０４ｍｓ）较右室心尖部起搏阈值（电压：５．０±６．０６Ｖ，脉宽：１．５２±０．７７ｍｓ）显著降低，Ｐ＜０．０１。随访６８．５±３４．６５个月无电极脱位，起搏功能良好。结果提示右室流出道是永久起搏可行的后备电极放置部位。     

Antianginal and myocardial metabolic properties of verapamil in coronary artery disease

To determine the metabolic cost of administering an experimental calcium antagonist, verapamil, to patients with coronary artery disease, 12 such patients were studied at rest and during stress with atrial pacing before and after intravenous treatment with verapamil (bolus dose of 0.1 mg/kg body weight, followed by infusion at 0.005 mg/kg per min). The mean (±standard deviation) aortic pressure at rest (98 ± 22 mg Hg), coronary sinus blood flow (88 ± 17 ml/min) and myocardial oxygen consumption (10.7 ± 2.4 ml O₂/min) decreased to 88 ± 20 mm Hg (p < 0.0004), 77 ± 14 ml/min (p < 0.03) and 8.8 ± 2.5 ml O₂/min (p < 0.01), respectively, after administration of verapamil. With atrial pacing, these values were 105 ± 25 mm Hg, 151 ± 50 ml/min and 18.5 ± 6.4 ml O₂/min, respectively, before infusion of verapamil, and then decreased to 87 ± 14 mm Hg (p < 0.006), 107 ± 31 ml/min (p < 0.0002) and 13.3 ± 4.4 ml O₂/min (p < 0.001) during infusion. Angina occurred in all patients with atrial pacing before verapamil (threshold to pain: 93 ± 67 seconds). After verapamil, the threshold to pain in six patients increased to 191 ± 183 seconds; and no pain was experienced by the remaining six (p < 0.0005). Before administration of verapamil lactate extraction decreased from 24 ± 9 to 10 ± 11 percent (p < 0.0002) during atrial pacing, and 9 (75 percent) of the 12 patients exhibited electrocardiographic S-T segment depressions. After administration of verapamil lactate extraction normalized to 22 ± 9 percent during atrial pacing, and the electrocardiogram reverted to baseline in all but one patient. These findings indicate that verapamil decreases left ventricular myocardial metabolic demands, and concomitantly greatly increases the threshold to angina.     

Hemodynamic and metabolic effects of diltiazem during coronary sinus pacing with particular reference to left ventricular ejection fraction

To determine the systemic and coronary hemodynamic effects of diltiazem at rest and during pacing, 14 patients with stable angina pectoris undergoing coronary angiography were studied before and after 0.165 mg/kg (n = 7) and 0.25 mg/kg (n = 7) of intravenously administered diltiazem. Hemodynamic variables, metabolic measurements and left ventricular (LV) ejection fraction (EF) were obtained at rest and during coronary sinus (CS) pacing before and during diltiazem administration. Lactate production during control pacing turned into extraction after diltiazem (p < 0.05). At rest, systemic resistance was reduced by 21% (p > 0.01) and mean arterial pressure by 12% (p < 0.01); cardiac index increased from 2.4 ± 0.4 to 2.6 ± 0.4 liters/min/m² (p < 0.01), with no significant change in heart rate. The mean pulmonary artery pressure increased from 17 ± 2 to 19 ± 3 mm Hg (p < 0.01), but other hemodynamic variables were not affected. Diltiazem given during pacing reduced the mean aortic pressure (from 112 ± 15 to 104 ± 15 mm Hg, p < 0.05), but other hemodynamic variables were not affected significantly. LVEF decreased 16%, from 0.63 ± 0.9 to 0.53 ± 0.8 with CS pacing (p < 0.01); when the pacing was performed after diltiazem administration the 8% decrease in LVEF from 0.64 ± 0.09 to 0.59 ± 13 was less marked (p < 0.01). Diltiazem had no significant effect on LVEF at rest. The overall data suggest that the ischemic manifestations of CS pacing are attenuated by diltiazem in doses of the drug that exert no significant depressant effect on LV function in patients with coronary artery disease.     

主动固定电极在右室流出道间隔部起搏中的应用研究

目的评价主动固定电极在右室流出道间隔部起搏应用中的可行性和稳定性。方法160例起搏适应证患者随机分为两组,每组80例,一组采用主动固定电极行右室流出道间隔部起搏(简称主动固定电极组),另一组应用被动固定电极行右室心尖起搏(简称被动固定电极组),观察电极置入时间和心电图QRS波宽度,电极置入后随访观察起搏阈值、感知、阻抗,电极脱位及相关并发症。结果主动固定电极组的置入时间和X线曝光时间均长于被动固定电极(26.34±6.54minvs20.86±4.32min,16.78±5.38minvs8.67±4.52min;P均<0.01)。主动固定电极组电极置入15min时较置入即刻的起搏阈值明显下降(0.76±0.21mVvs1.12±0.25mV,P<0.01)。主动固定电极组起搏的QRS波时限较被动固定电极组短(0.14±0.04msvs0.16±0.03ms,P<0.01)。术后随访1,3,6个月,两组的起搏阈值、感知、阻抗均无差异,未见电极脱位等并发症。结论主动固定电极在右室流出道间隔部起搏中的应用是可行和稳定的。     

Radionuclide evaluation of postextrasystolic potentiation of left ventricular function induced by atrial and ventricular stimulation

Postextrasystolic potentiation of left ventricular function induced by ventricular and atrial stimulation was compared in 10 patients using radionuclide ventriculography. After insertion of pacing wires, a preliminary radionuclide ventriculogram was obtained and then ventricular and atrial trigeminy was induced in random order, each with identical R-R coupling intervals, each for 6 to 10 minutes. During the stimulation studies, radionuclide data were acquired in electrocardiographic gated list mode format. Left ventricular ejection fraction and relative end-diastolic and end-systolic volume changes were measured for each reformatted composite sinus, atrial and ventricular premature beat and potentiated beat. The volume changes were normalized to the count-based values obtained for the sinus beat of the appropriate study. Postextrasystolic potentiation induced by either ventricular or atrial stimulation was characterized by similar significant increases in left ventricular ejection fraction (mean ± standard deviation 7 ± 3 percent, p < 0.01 versus 7 ± 5 percent, p < 0.01; difference not significant [NS]) and decreases in relative end-systolic volume (?12 ± 12 percent, p < 0.01 versus ?12 ± 8 percent, p < 0.01; NS) but little change in relative end-diastolic volume (+5 ± 10 percent, NS versus +4 ± 7 percent, NS; NS). This was despite a longer compensatory pause (1,120 ± 220 versus 1,050 ± 190 ms, p < 0.01) after the ventricular premature beat. It is concluded that there is no difference in the postextrasystolic potentiation induced by atrial or ventricular premature stimulation.     

双心室起搏埋藏式心脏转复除颤器的安置

评价一次性置入双心室起搏埋藏式心律转复除颤器 (双腔ICD)的安全性和有效性。5例冠心病冠状动脉搭桥术后的患者 ,伴有严重的慢性充血性心力衰竭和恶性室性心律失常 ,置入双腔ICD。结果 :5例左室电极导管和双腔ICD均一次成功置入 ,左室电极放入冠状静脉的侧后枝 ,急性起搏阈值 0 .8± 0 .6V ,电阻 72 2± 12 8Ω ,R波振幅18.6± 5 .3mV ,电流 1.6± 0 .5mA ,而双心室起搏时其起搏电极参数均优于左室电极 ,除颤阈值≤ 14J。结论 :对伴严重慢性充血性心力衰竭和恶性室性心律失常的患者 ,置入双腔ICD是安全、易行的。     

Implantable cardioverter-defibrillators in patients with arrhythmogenic right ventricular cardiomyopathy: the course of electronic parameters,clinical features,and complications during long-term follow-up

Purpose

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a progressive cardiomyopathy characterized by myocardial atrophy and fibro-fatty replacement of the right ventricle (RV) and ventricular tachyarrhythmias in young patients. Our aim was to evaluate clinical course and electronic parameters in patients with implantable cardioverter-defibrillator (ICD) and ARVC, during long-term follow-up.

Methods and results

We report on 12 patients with ARVC (mean age 40?±?13 years) who were treated with ICD implantation in our center. Although several RV sites were tested for proper lead positions, the amplitude of R-wave at implantation was quite low (7.4?±?3.0 mV). After a mean follow-up of 91?±?28 months, R-wave amplitude significantly decreased to a mean value of 5.4?±?2.5 mV (p?=?0.03). We also found a noticeable, nearly significant increase in pacing threshold (p?=?0.052) and a moderate increase in defibrillation impedance (p?=?0.07). Six patients (46 %) experienced at least one appropriate ICD therapy; three patients (23 %) experienced inappropriate ICD shocks secondary to the supraventricular tachycardia, T-wave oversensing, and electromagnetic interference.

Conclusions

ICD in patients with ARVC has been demonstrated to be feasible and safe. In our case series, we found low R-wave amplitudes at implantation and a significant R-wave decrease during follow-up; a considerable and nearly significant increase in pacing threshold was also observed. These findings may be related to the progressive fibro-fatty replacement of RV myocardium. Multiple sites should be tested in the right ventricle if sensing or pacing values are not optimal, and all the electronic parameters should be carefully monitored throughout the entire follow-up.     

Ventricular activation during ventricular endocardial pacing: I. Electrocardiographic patterns related to the site of pacing

The QRS configuration produced by pacing at multiple left ventricular endocardial sites was evaluated in eight patients with (group 1) and six patients without (group 2) left ventricular wall motion abnormalities. Pacing was performed at a total of 122 sites, 4 to 13 sites in each patient. The QRS configuration resulting from apical pacing locations was compared with that at basal, septal to lateral and inferior to superior locations. Significant differences in QRS configuration during pacing from apical and basal locations were observed in electrocardiographic leads I, V₁, V₂ and V₆ (probability [p] < 0.01). Specifically, a QS pattern in leads I, V₂ and V₆ was more characteristic of an apical pacing location (p < 0.001), and a monophasic R wave in leads V₁ and V₂ was more characteristic of a basal pacing location (p < 0.01). Significant differences in leads V₁ and V₂ were observed when septal and lateral pacing sites were compared (p < 0.001). A monophasic R wave in leads V₁ and V₂ was more characteristic of a lateral pacing location (p < 0.01); a QS complex in lead V₂ was more characteristic of a septal pacing location (p < 0.001). Pacing at superior sites usually produced an inferior axis and vice versa (p < 0.001). The electrocardiographic patterns produced by pacing at similar sites in patients in group 1 were less consistent than those in patients in group 2. The QRS complex during ventricular pacing was wider in patients in group 1 (159 ± 30 ms) than in patients in group 2 (132 ± 18 ms) (p < 0.001).It is concluded that the QRS configuration recorded with 12 lead electrocardiography during endocardial pacing can help locate the region of the pacing site in patients with and without organic heart disease, although precise localization is not possible.     

右室双部位起搏治疗心力衰竭的临床观察

评价 15例患者经右室双部位起搏治疗慢性心力衰竭 (简称心衰 )的疗效。其中原发性扩张型心肌病心衰 13例、缺血性心肌病心衰 2例 ;心功能Ⅲ级 9例、Ⅳ级 6例。结果 :15例患者安置时右室心尖部起搏阈值 0 .5± 0 .3(0 .3～ 1.0 )V、R波振幅 15± 5 .98(6～ 2 4.6 )mV ,阻抗 6 13± 172 (32 0～ 90 0 )Ω。右室流出道起搏阈值 0 .7± 0 .2 6 (0 .3～1.3)V、R波振幅 13± 5 .5 5 (6 .5～ 2 3.6 )mV、阻抗 5 6 3± 194(30 0～ 90 0 )Ω ;双部位起搏阈值 1.45± 0 .45 (0 .9～ 1.7)V。双部位起搏心电图QRS波群时限比右室心尖部及右室流出道单部位起搏缩短了 40～ 90ms。超声心动图检查提示双部位起搏后二尖瓣返流面积平均减少 5 .6cm2 ,射血分数值提高 5 .2 %。经 6 .0± 1.5个月的随访 ,15例中除 2例因突发恶性室性心律失常猝死外 ,其余患者的心功能分别从Ⅲ、Ⅳ级改善到Ⅱ和Ⅲ级。右室双部位慢性起搏阈值1.85± 0 .5 6 (1.5～ 2 .5 )V。随访期间QRS波群时限平均下降 5 0ms。结论 :右室双部位起搏能有效的治疗心肌病患者的心衰。