Long-Term Stability of P Wave Sensing in Single Lead VDDR Pacing: Clinical Versus Subclinical Atrial Undersensing

Optimal function of a single lead P wave synchronous rate adaptive ventricular pacing system (VDDR) requires reliable P wave sensing over time and during daily activities. The stability of P wave sensing and the incidence of sensitivity reprogramming in a single pass lead with a diagonally arranged bipole was assessed in 30 patients with complete atrioventricular block over a follow-up period of 12 ± 1 months (range 6 months to 3 years). Atrial sensing was assessed during clinic visits, by physical maneuvers (postural changes, breathing, Valsalva maneuver, walking and isometric exercise), maximum treadmill exercise and Holter recordings. P wave amplitude at implantation was 1.21 ± 0.09 (0.5–3.6) mV, and the atrial sensing threshold remained stable over the entire period of follow-up. Using an atrial sensitivity based on twice the sensing threshold at 1 month, P wave undersensing was found in 2, 4, 3, and 7 patients during clinic visit, physical maneuvers, exercise, and Holter recordings, respectively. Atrial sensitivity reprogramming was performed in three patients based on the correction of undersensing during physical maneuvers. Although eight patients had atrial undersensing on Holter recordings, the number of undersensed P waves was small (total 101 beats or 0.013%± 0.001% of total ventricular beats) and no patient was symptomatic. One patient had intermittent atrial undersensing at the highest sensitivity, but the VDDR mode was still functional most of the time. No patient had myopotential interference at ihe programmed sensitivity. One patient developed chronic atrial fibrillation and was programmed to the VVIR mode. Thus, single lead VDDR pacing is a stable pacing mode in 97% of patients. Because of the large variability of P wave amplitude, the use of a sensitivity margin at least three times the atrial sensitivity threshold will maximize atrial sensing and minimize the need for atrial sensitivity reprogramming (1/30 patients). Physical maneuvers and exercise tests are effective means for rapid assess ment of the adequacy of P wave sensing.     

Comparative Evaluation of Bipolar Atrial Electrogram Amplitude During Everyday Activities: Atrial Active Fixation Versus Two Types of Single Pass VDD/R Leads

Endocardial P wave amplitude (PWA) is an important determinant of the atrial sensing capabilities of an atrial-based pacing system. Although changes in PWA during physical activities are known to occur in DDD/R pacing, there is little information on the P wave stability in single pass lead VDD/R pacemakers using floating P wave sensing. We investigated the variation of PWA during daily life activities using telemetry recorded atrial electrograms in 21 patients with DDDR pacemakers (Relay or Elite) and 29 patients with single lead VDD/ R pacemakers (Unity or Thera). Physical activities resulted in marked individual variability of PWA but, as a group, there was no significant difference between PWA during sitting, standing, lying down, and coughing in both DDDR and VDD/R pacing. In the Elite II pacemaker, walking at 2 miles per hour resulted in significant reduction of PWA (11.6% compared with sitting, P < 0.05). The most consistent reduction in PWA occurred in the relaxation phase of the Valsalva maneuver (VM), with all pacemakers showing a reduction in PWA (mean reduction in PWA compared with sitting in DDDR and VDD/R were 16.6% and 12.8%, respectively). Two patients with DDDR pacemakers (Relay) and three patients with VDD/R pacemakers (1 Unity and 2 Thera) had atrial sensing failure during VM or walking. In conclusion, large variation in PWA occurs during daily life activities. The extent of variation is dependent on the patients, types of atrial lead, and the maneuvers performed. A twice sensing threshold may be insufficient to ensure adequate atrial sensing during these activities. The VM, which effects a consistent change in intracardiac volume, is the most reliable method for bedside evaluation of the lower end of sensitivity margin.     

用桡动脉脉搏波估测硝酸甘油对中心动脉压的影响

目的：通过测量桡动脉波定量硝酸甘油降低中心动脉反射波增压的效应。方法：１９名志愿者,年龄５４±７岁,无严重器质性疾病,试验前停用所有心血管药物至少３天,试验当天禁食。先测基础仰卧位肱动脉血压和桡动脉脉搏波,随后随机贴上安慰剂或 ５ ｍｇ硝酸甘油贴剂,每隔半小时以同样的方式记录血压和脉搏波,共 ５个小时后撕去贴膜,再记录 ２ 小时。动脉脉搏波分析仪实时把桡动脉脉搏波换算为中心动脉脉搏波,显示中心动脉反射波增压（ＡＵＧ）和中心动脉反射波增压指数（ＡＩ）。结果：安慰剂组（９例）,用药前后比较,心率（ＨＲ）,射血时间（ＥＤ）,肱动脉收缩压（ＰＳＰ）,肱动脉舒张压（ＰＤＰ）和肱动脉平均压（ＰＭＰ）及计算的中心动脉波增压、增压指数、中心动脉收缩压等各项参数均无显著变化。 ５ ｍｇ硝酸甘油贴剂组 （ １０例）用药前后比较,射血时程、中心动脉波增压、增压指数、中心动脉收缩压在用药后半小时即显著下降,至３．５小时达高峰,撕去贴膜后２小时恢复到基础水平,但心率、肱动脉收缩压、肱动脉舒张压和肱动脉平均压无明显变化。结论：通过分析桡动脉脉搏波,可以定量中心动脉反射波增压,阐明硝酸甘油的作用,显示其起效、维持、撤除的动态变化,同时也阐明了硝酸     

用桡动脉脉搏波估测硝酸甘油对中心动脉压的影响

目的:通过测量桡动脉波定量硝酸甘油降低中心动脉反射波增压的效应 .方法:19名志愿者,年龄54±7岁,无严重器质性疾病,试验前停用所有心血管药物至少3天,试验当天禁食.先测基础仰卧位肱动脉血压和桡动脉脉搏波,随后随机贴上安慰剂或5 mg硝酸甘油贴剂,每隔半小时以同样的方式记录血压和脉搏波,共5个小时后撕去贴膜,再记录2小时.动脉脉搏波分析仪实时把桡动脉脉搏波换算为中心动脉脉搏波,显示中心动脉反射波增压(AUG)和中心动脉反射波增压指数(AI).结果:安慰剂组(9例),用药前后比较,心率(HR),射血时间(ED),肱动脉收缩压(PSP),肱动脉舒张压(PDP)和肱动脉平均压(PMP)及计算的中心动脉波增压、增压指数、中心动脉收缩压等各项参数均无显著变化.5 mg硝酸甘油贴剂组 (10例)用药前后比较,射血时程、中心动脉波增压、增压指数、中心动脉收缩压在用药后半小时即显著下降,至3.5小时达高峰,撕去贴膜后2小时恢复到基础水平,但心率、肱动脉收缩压、肱动脉舒张压和肱动脉平均压无明显变化.结论:通过分析桡动脉脉搏波,可以定量中心动脉反射波增压,阐明硝酸甘油的作用,显示其起效、维持、撤除的动态变化,同时也阐明了硝酸甘油的有益效应伴随外周血管波反射降低所致的动脉脉搏波的显著变化.     

经胸RT-3DE技术在观察房颤患者冠状静脉窦结构中的应用

目的 评价经胸实时三维超声心动图（RT-3DE）技术观察心房颤动（房颤）患者冠状静脉窦（CS）结构的可行性及其潜在临床价值.方法 对40例房颤患者（房颤组）和64例窦性心律者（窦律组）采用经胸RT-3DE行实时三维全容积显像,依次多方向切割,观察CS显像情况.结果 在经胸RT-3DE显像下,两组CS均可采取自外而内及自内而外的观察,并可经右房观察到CS开口;窦律组能清晰显示CS者56例（87.5%）、未能清晰显示8例（12.5%）,房颤组分别为33例（82.5%）、7例（17.5%）,两组显像率比较P〉0.05（χ2=0.499）.结论 经胸RT-3DE可对CS进行无创性全方位观察,在房颤治疗及随访中可能具有一定临床价值,但尚需进一步研究.     

老年冠心病患者经皮冠状动脉介入治疗分析

目的 探讨老年与非老年冠心病患者择期经皮冠状动脉介入治疗(PCI)的特点.方法 217例冠心病患者,依年龄分为老年组(＞65岁)72例和非老年组(≤65岁)145例,冠状动脉造影(CAG)显示404处病变,相应接受了245次PCI治疗,其中有153例患者成功植入冠状动脉支架172枚,记录术中并发症以及术后住院期间主要不良心脏事件(MACE)发生情况,结合病史分析两组特点及区别.结果 老年组女性患者比例、高血压、糖尿病、不稳定型心绞痛发生率、多支病变率、手术并发症发生率、支架植入率均高于非老年组;但老年组吸烟率、合并高脂血症及单支病变率均低于非老年组;两组患者重度血管狭窄(狭窄≥90％)率及手术成功率相似(P＞0.05).结论 老年组与非老年组相比,PCI的手术成功率差异无统计学意义,但老年组手术并发症以及手术后MACE发生率高于非老年组,因此,对老年患者行PCI治疗前应权衡利弊.     

阿托伐他汀早期干预对急性心肌梗死患者血清一氧化氮及一氧化氮合酶含量的影响

目的观察阿托伐他汀对急性心肌梗死患者血清一氧化氮(NO)及一氧化氮合酶(NOS)水平的影响。方法急性心肌梗死患者分为两组,治疗组入院后予阿托伐他汀10mg QN,对照组予常规治疗。治疗前及治疗后2周测定血清NO及NOS含量水平。结果阿托伐他汀可以提高急性心肌梗死患者血清NO及NOS水平。结论阿托伐他汀通过诱导血管内皮细胞分泌NO,保护血管内皮功能,对急性心肌梗死的治疗具有重要意义。     

内源性促红细胞生成素与慢性心力衰竭

贫血常见于慢性心力衰竭(CHF)患者,其与CHF患者症状和心功能恶化以及死亡率增加有相关性。CHF患者内源性促红细胞生成素(EPO)水平上调,并与CHF严重程度相关。研究发现,EPO水平是CHF患者死亡和因心力衰竭再住院的强预测指标,并独立于血红蛋白水平以及其它已经确定的CHF严重程度的标志物。与非CHF患者相比,CHF患者EPO与血红蛋白水平仅呈弱相关性。     

ERCP治疗肝移植术后胆道并发症的疗效评价

目的 探讨ERCP在治疗肝移植术后胆道并发症方面的作用.方法 回顾性分析2004年10月至2007年10月采用ERCP治疗39例肝移植术后胆道并发症患者的临床资料.对25例胆道狭窄患者(吻合口狭窄14例,非吻合口狭窄11例)行括约肌切开、胆管扩张、鼻胆管引流和塑料内支架置放术等治疗;对6例胆漏患者行鼻胆管引流及塑料内支架置放术等治疗;对16例胆道结石和胆泥形成患者(其中合并胆道狭窄8例)行括约肌切开、鼻胆管冲洗引流及取石网篮取石等治疗.结果 ERCP手术成功率为95.9%(94/98),未出现严重并发症.吻合口狭窄的ERCP治愈率为100%(14/14),非吻合口狭窄的ERCP治愈率为27.3%(3/11),胆漏的ERCP治愈率为83.3%(5/6),结道结石和胆泥形成患者的ERCP治愈率为81.3%(13/16).结论 ERCP治疗肝移植术后胆道并发症安全性较高、疗效较好、严重并发症发生率较低.     

ERCP治疗肝移植术后胆道并发症的疗效评价

目的 探讨ERCP在治疗肝移植术后胆道并发症方面的作用.方法 回顾性分析2004年10月至2007年10月采用ERCP治疗39例肝移植术后胆道并发症患者的临床资料.对25例胆道狭窄患者(吻合口狭窄14例,非吻合口狭窄11例)行括约肌切开、胆管扩张、鼻胆管引流和塑料内支架置放术等治疗;对6例胆漏患者行鼻胆管引流及塑料内支架置放术等治疗;对16例胆道结石和胆泥形成患者(其中合并胆道狭窄8例)行括约肌切开、鼻胆管冲洗引流及取石网篮取石等治疗.结果 ERCP手术成功率为95.9%(94/98),未出现严重并发症.吻合口狭窄的ERCP治愈率为100%(14/14),非吻合口狭窄的ERCP治愈率为27.3%(3/11),胆漏的ERCP治愈率为83.3%(5/6),结道结石和胆泥形成患者的ERCP治愈率为81.3%(13/16).结论 ERCP治疗肝移植术后胆道并发症安全性较高、疗效较好、严重并发症发生率较低.