Use of Telemetered Electrograms in the Assessment of Normal Pacemaker Function

The facility of direct real-time endocardial electrogram recording offered by newer pacemaker models can be helpful in the assessment of normal pacemaker function. Confirmation of the main hallmarks of sensing (amplitude, slew rate, and timing of the electrogram) can be achieved. Assessment of pacing capture also can be made; techniques for further analysis using external signal averaging can enhance this. The measurement of atrial and ventricular electrograms by telemetry has led to alterations in the protocol used at implantation to allow for the input impedance of the sensing circuit of the pacemaker. Accurate measurements of retrograde VA conduction times and confirmation of normal upper rate limit behavior of ODD pacemakers can be achieved simply and reliably using telemetered electrograms from the permanent pacemaker system.     

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.     

Visualisation of intra-cardiac structures and radiofrequency lesions using intracardiac echocardiography.

AIMS: Fluoroscopy does not allow identification specific anatomical landmarks during electrophysiological studies. Intra-cardiac echocardiography permits visualization of these structures with excellent accuracy, but the optimal method has not been fully described. The aim of this study was to assess the capability of intra-cardiac echocardiography for the visualization of such structures using two different approaches. We also assessed its capability for the evaluation of radio frequency lesions 20 min after catheter ablation of the cavo-tricuspid isthmus. METHODS: Intra-cardiac echocardiography was performed using a 9 MHz rotating transducer in eight consecutive patients (age range: 37-76 years) after radio frequency ablation of the cavo-tricuspid isthmus. The ultrasound catheter was inserted through the femoral vein into the superior vena cava and was pulled back to the inferior vena cava. The echo catheter was then reinserted through the subclavian vein and advanced into the right ventricular apex and was pulled back from the right ventricular to the superior vena cava. Qualitative evaluation and intra-cardiac measurements were performed off-line. RESULTS: The fossa ovalis, the tricuspid valve, and the terminal crest were visible in all patients regardless of the method of introduction of the echo catheter. Left-sided structures were less accurately seen by intra-cardiac echocardiography. The horizontal diameter of the fossa ovalis was 8.9+/-1.8mm. The cavo-tricuspid isthmus was visible using the femoral approach in three patients. The isthmus could be visualized in all patients, and in three patients together with the ostium of the coronary sinus, using the subclavian approach. radio frequency lesions were not visible 20 min after ablation. Additionally, both the left and right ventricles could be seen using the subclavian approach. CONCLUSIONS: The subclavian approach is feasible, safe and superior to visualize the isthmus. Twenty minutes after radio frequency ablation of the cavo-tricuspid isthmus radio frequency lesions are not visible using intra-cardiac echocardiography.     

体外培养新生大鼠心房壁中的CGRP-IR和NPY-IR神经细胞

对体外培养新生SD大鼠心房壁的神经细胞，按SternbergerPAP法进行了降钙素基因相关肽（CGRP）和神经肽Y（NPY）免疫细胞化学研究。结果显示：CGRP-IR阳性细胞数量较少，实验的5份标本只有2份见到阳性细胞，而NPY-IR阳性细胞在所有实验标本中均可见到。本研究在培养条件下证实心内神经节中有CGRP-IR阳性细胞存在，支持心脏有器官内感觉神经细胞的设想。同时对心内神经细胞的化学性质进行了讨论。     

Intra-Hisian Block Associated with Unusual Etiologies

One hundred and sixty-nine patients underwent electrophysiologic study for atrioventricular block. Forty-five (27%) had intra-Hisian block. Four of these 45 patients had unusual etiologies: rheumatoid arthritis, cysticercosis cellulosae, Behcet's disease, and Takayasu aorto-arteritis. Their clinical and electrophysiologic features are described in detail.     

房室传导阻滞的希氏束电图研究

研究了19例AVB的希氏束电图(HBE)。经皮穿刺股静脉将三极导管送至心脏希氏束部位,记录HBE。一度AVB5例,其中4例阻滞于房室结内,1例在希氏束内;二度AVB4例,3例阻滞于房室结,1例在希浦系;三度AVB10例,5例阻滞于房室结内,4例在希氏束,1例在希浦系。HBE能确定房室传导的阻滞部位,对指导安装起搏器和判断预后有一定意义。     

Anticoagulation therapy for pulmonary embolism involving a myxoma mimicking,giant type C thrombus: A case report

Right heart thrombus (RHTh) with concurrent acute pulmonary embolism (PE) is rare and can seriously destabilize hemodynamics, leading to an emergency situation with high mortality. Diagnosis and treatment of RHTh with acute PE are not yet standardized. There are few reports of acute PE concurrent with RHTh and even less is known about patients with a right heart mural thrombus. For physicians, the diagnostic choice and treatment of these patients are particularly difficult due to the lack of knowledge. Here, we report a rare case of partial mural RHTh (type C RHTh) with acute PE. The mural mass in the right heart was initially diagnosed as atrial myxoma according to transthoracic echocardiography (TTE), and both pulmonary embolus and the mural mass were completely absorbed after administering Rivaroxiban. This case suggests that TTE alone is insufficient to identify and diagnoses a right heart mural mass such as this. However, novel oral anticoagulants may be effective at alleviating PE with type C RHTh.     

血浆异钩藤碱浓度对兔心率及希氏束电图的影响

目的 观察血浆异钩藤碱浓度对兔心率及希氏束电图的影响。方法 心房起博及希氏束电图方法。结果 血浆异钩藤碱浓度在0．73－3．68mg/L范围内呈剂量依赖性减慢心率、延长窦房结传导时间、窦房结恢复时间、心房－希氏束间期、希氏束－心室间期、以及心电图的P－R间期,其中对心率和房室传导抑制明显。结论 异钩藤碱用于对抗扩血管药引起的加快的心率的副作用时,血药浓度控制在1－2mg/L为宜。     

先天性心脏病心脏停跳和不停跳下心内直视手术的临床分析

目的　对比分析心脏停跳和不停跳心内直视手术治疗先天性心脏病心内畸形的疗效。方法　5 5 8例患者分别采用心脏停跳手术 2 31例 ,不停跳手术 32 7例。心脏不停跳心内直视手术仍常规建立体外循环 ,置左心房引流管 ,降温至 (32± 1)℃并维持 ,仅阻断上下腔静脉 ,不阻断主动脉 ,维持灌注压在 8kPa左右 ,心脏跳动下进行畸形矫正 ,方法同停跳下手术。结果　不停跳组早期死亡 7例 (死亡率 2 .14 % ) ,停跳组早期死亡 5例 (死亡率 2 .17% ) ,其余均痊愈出院 ,随访 3～ 2 3月 ,恢复良好。结论　心脏不停跳心内直视手术 ,是一种有效的心肌保护方法 ,并可简化操作 ,缩短体外循环时间     

心房按需起搏时心内电图的形态与起搏参数的关系

目的： 观察心房按需起搏（ＡＡＩ）时心内电图的形态与起搏阈值等参数的关系。　方法：对３６ 例ＡＡＩ起搏时记录的心内电图的Ａ 波形态、振幅、Ａ－Ｖ段上抬幅度进行详细测定,并与起搏阈值、心肌阻抗等参数进行相关分析。　结果：Ａ波形态、振幅与起搏阈值、心肌阻抗均无显著相关（Ｐ＞ ０．０５）,而Ａ－Ｖ 段上抬的幅度与起搏阈值呈明显负相关（ｒ＝ － ０．５４８ ６, Ｐ＜ ０．０５）。Ａ－Ｖ段高抬组的起搏阈值（０．６８±０．１７）Ｖ,显著低于Ａ－Ｖ段低抬组的（１．１±０．２４）Ｖ （Ｐ＜ ０．０１）。　结论：心内电图Ａ－Ｖ段上抬的足够幅度（＞ ０．３ ｍ Ｖ）可作为ＡＡＩ起搏时的一个重要技术指标,对避免电极脱位、保证较低的起搏阈值水平均具重要的临床意义。