Atrial Synchronous Ventricular Pacing with a Single Lead: Reliability of Atrial Sensing During Physical Activities, and Long-term Stability of Atrial Sensing

A VDD pacing system with bipolar single-pass leads, were implanted in 36 consecutive patients (average age 72 ± 2years) with high degree atrioventricular block and normal sinus node function. At implant the atrial signal amplitude was 2.6 ± 0.2mV measured by a pacing system analyser (PSA), 1.8 ± 0.1mV measured peak-to-peak from the telemetered calibrated electrogram, and 1.3 ± 0.1mV measured from the sensing threshold. At one month follow-up the peak-to-peak amplitudes (mV) of the telemetered atrial electrograms were not significantly different measured continuously during resting supine with quiet breathing (1.4 ± 0.1), sitting (1.6 ± 0.2). standing (1.5 ± 0.1), arm swinging (1.4 ± 0.2), hyperventilation (1.3 ± 0.1), Vaisalva manoeuvre (1.4 ± 0.1), and treadmill exercise (1.9 ± 0.6). The telemetered atrial electrogram amplitude and the atrial sensing threshold varied between 1.2 ± 0.09mV and 1.8 ± 0.1mV, and between 0.95 ± 0.07mV and 1.3 ± 0.01mV, respectively at 0.5, 1, 3, 6 and 12 months follow-up, but the changes were statistically nonsignificant. The Event Summary showed sensing of 98% to 99% of the atrial events at the different follow-up periods.     

非瓣膜病房颤患者左心耳血流动力学的TEE研究

应用多平面经食管超声心动图技术（Ｍ－ＴＥＥ），对３０例健康人和３０例非瓣病房颤患者（ＮＶＡＦ）心底短轴切面测量了左心耳最大直径，同一心动周期内左心耳最大及最小面积及左心耳最大空速度，产将ＮＶＡＦ患者按照自发显影及血栓的有无分为２组。发现ＮＶＡＦ组左心耳增大，收缩力及血流速度均减低，且这种变化在有血栓和有血栓形成倾向的患者中更为明显。     

Atypical Form of the Fourth Criterion for Transient Entrainment

The typical fourth criterion for transient entrainment is defined when both a sudden shortening in conduction interval to and a distinct change in electrogram morphology at a bipolar recording site are demonstrated while performing overdrive pacing of a reentrant tachycardia from a single pacing site at two different constant rates. The purpose of this article was to test the hypothesis that if an intracardiac recording site showing both orthodromic and antidromic capture with entrainment pacing is located suitably distant from the circuit, sudden shortening in conduction interval to that site may occur without any significant change in the bipolar electrogram morphology (i.e., atypical form of the fourth criterion). Atrial overdrive pacing of orthodromic tachycardia was performed in 20 patients with either left anterior (12 patients) or left posterior (8 patients) accessory pathways. We investigated the effects of overdrive pacing from the proximal or distal coronary sinus, specifically effects on the electrogram interval and the electrogram morphology at the right atrial appendage. Overdrive pacing of orthodromic tachycardia from the proximal coronary sinus was performed in 10 of the 12 patients with left anterior accessory pathways; those 10 patients demonstrated the first entrainment criterion at the right atrial appendage site. Overdrive pacing of orthodromic tachycardia at still shorter cycle lengths demonstrated a sudden shortening in conduction interval to the right atrial appendage site. Despite shortening in conduction interval the morphology of the right atrial appendage electrogram was completely or almost identical to that during orthodromic tachycardia, indicating an atypical form of the fourth criterion. This criterion was not demonstrated in patients with left posterior accessory pathways. Thus, atypical fourth entrainment criterion was demonstrated during overdrive pacing of orthodromic tachycardia from the proximal coronary sinus only in patients with left anterior accessory path ways. Demonstration of atypical fourth criterion seems largely dependent on the location of the accessory pathway, the pacing, and the recording sites.     

慢性肺心病左心功能探讨

通过42例重型肺心病、7例轻型肺心病、16例肺心病伴发冠心病患者和30例正常人在静息状态下的左右心脏射血分数及其临床资料的分析表明,重型肺心病患者在病情的急性发作期,存在有不同程度的左心功能不全,而轻型肺心病患者则无左心功能不全的表现。表明慢性肺心病仅在病程晚期,才由以右心为主的疾病发展成为全心病。本文还对重型肺心病与肺心病伴发冠心病患者的左心功能进行比较,结果表明,肺心病伴发冠心病患者左室功能受损程度更为明显,双重病因导致的左室功能减退,常造成心肌更严重的损害而且不容易恢复。     

术前左室射血分数及短缩分数对冠状动脉旁路术后恶性心律失常的预测价值

为了评价冠状动脉旁路术 (CABG)术前左室射血分数 (LVEF)及左室短缩分数 (LVFS)对术后室性心律失常 (VA)预测的准确性 ,采用术前及术后 2周心脏彩超EF、FS值 (面积长轴法 )、心室晚电位 (VLP)、心肌酶、持续心电监测的方法 ,对我院 1 5 0例行CABG术的患者进行分析。结果 :1 )术前心肌梗死 (MI)、室壁瘤、VA及VLP阳性患者EF、FS值明显减低 ;2 )术前左心功能不全 (LVD)患者术后EF、FS值明显改善 ;3 )术前LVD、VA、VLP阳性及室壁瘤患者术后VA发生率明显高于其他患者。提示 :1 )面积长轴法EF、FS值是反映左心功能的敏感指标 ;2 )术前LVD患者术后短期左心功能明显好转 ,获益最大 ;3 )非LVD患者术后因心肌顿抑导致近期心功能暂时下降 ;4 )EF≤ 4 0 %和(或 )FS≤ 2 4 %是预测术后VA的独立指标 ,FS较EF更能准确地反映心脏收缩功能 ;5 )LVD、VLP、室壁瘤等综合指标分析有助于提高对术后VA预期的敏感性、特异性和准确性     

Donor left ventricular hypertrophy increases risk for early graft failure

A review of factors contributing to early mortality after cardiac transplantation revealed that up to 25 % of deaths were due to primary graft dysfunction unrelated to rejection or infection. In light of this finding, evaluation of a donor heart with regard to its suitability for transplantation takes on added importance. In an effort to screen the suitability of donor hearts in the region covered by the Northwest Organ Procurement Agency (USA), all donors are evaluated by two-dimensional transthoracic echocardiography as part of the initial evaluation. A total of 110 donor echocardiograms were reviewed and an attempt was made to correlate the 30-day outcome with the parameters measured. An unexpected finding was that the presence of left ventricular hypertrophy in the donor heart was associated with an increase in the incidence of donor heart dysfunction compared with donors with normal echocardiographic profiles (33 % vs 3 %, P = 0.007). Received: 12 February 1996 Received after resision: 27 June 1997 Accepted: 14 July 1997     

房间隔入路的解剖学研究及临床应用

对３３具尸体的房间隔的大小、构成及周围重要组织结构进行观察和测量。提出房间隔切开时的正确方向、安全长度及可能发生的危险。结合４６６例临床应用，讨论了避免切口合并症发生及发生后的正确处理方法。     

THE EFFECT OF HYPERTENSIVE EPISODES AND CARDIAC HYPERTROPHY ON THE CANINE CARDIAC BAROREFLEX

1. Left ventricular (LV) hypertrophy has been implicated in the reduction of baroreflex sensitivity present in hypertension. The aim of the current study was to investigate the mean arterial pressure-heart rate reflex (MAP-HR) in a model which induced left ventricular hypertrophy but no sustained blood pressure elevation. 2. Five mongrel dogs were exposed to transient blood pressure elevation of between 20 and 30 mmHg, through hindlimb compression using a pneumatic pressure suit, for 7 h per day, 6 days per week for 6 weeks. Resting blood pressure was not altered by the 6 week hindlimb compression intervention. 3. Echocardiographically determined LV mass (mean ± s.e.m.) was 116.0 ± 7.4 g prior to hindlimb compression (baseline) and elevated to 125.4 ± 8.1 g (P= 0.003) after 6 weeks of compression. A reduction in the early (E) to late (A) transmitral diastolic flow ratio (E/A) from 1.80 ± 0.06 at baseline to 1.54 ± 0.09 (P = 0.037) after the 6 week intervention suggested that cardiac compliance was reduced. 4. The maximum gain of the MAP-HR reflex, studied using the ‘steady-state’ drug technique, when blood pressure was normal, showed a trend for reduction from 3.85 ± 0.43 beats/min per mmHg at baseline to 3.10 ± 0.45 beats/min per mmHg (P= 0.067) after 6 weeks of compression. This gain reduction became significant after β-adrenoceptor blockade with propranolol (3.13 ± 0.55 vs 2.32 ± 0.25 beats/min per mmHg; P= 0.039). Covariant analysis showed a significant inverse correlation between LV mass and maximum gain (r= 0.96; P<0.001) during the 6 week compression period. 5. The MAP-HR reflex changes in this model mimic those present in hypertension and implicate cardiac hypertrophy as one possible mediator.     

Stenting of the left carotid artery to relieve anginal symptoms.

Stenting of the carotid artery is usually performed either to prevent an acute neurologic event or to treat episodes of recurrent transient ischemic attacks. Occasionally, it may be performed for other indications. We describe the case of a patient with prior coronary artery bypass grafting using a left internal mammary arterial graft, in addition to left carotid artery to left subclavian artery bypass for symptomatic left subclavian stenosis, who subsequently underwent left common carotid artery stenting to relieve anginal symptoms.     

重组促红细胞生成素对腹膜透析患者心功能的影响

目的　了解基因重组人促红细胞生成素 (r HuEPO)对持续性非卧床腹膜透析 (CAPD)患者心室结构及功能的影响。方法　 32例CAPD伴高血压患者 ,其中 1 6例应用降压药物控制血压 ,同时应用r HuEPO纠正贫血 ,1 6例单用降压药物 ,随访 6个月。结果　两组治疗前后差值比较 ,治疗组的LVPWT、E/A与对照组比较有显著差异(P <0 .0 5 )。结论　长期纠正贫血和控制血压有利于透析患者左室结构及功能异常的逆转