Left atrial appendage function in patients with different pacing modes

Many studies suggest that patients who receive a ventricular pacemaker have a higher incidence of systemic thromboembolism compared to patients receiving a physiological pacemaker. However, the exact mechanism regarding the etiology of thromboembolism remains unclear. We evaluated the left atrial appendage (LAA) functions, using multiplane transesophageal echocardiography (TEE), in patients with different pacing modes. In order to evaluate the ejection fraction (EF), peak emptying (V(E)) and filling (V(F)) flow velocities of the LAA by TEE, we studied 31 patients (mean age 63+/-18.5 years) who had been paced for 5.0+/-2.9 years. Patients with atrial fibrillation, left ventricular dysfunction and mitral valve disease were excluded. The pacing indications were complete atrioventricular block (AVB) in 19 patients (9 VVI, 10 VDD or DDD) and sick sinus syndrome (SSS) in 12 patients (5 VVI, 7 DDD). Mean EF, V(E) and V(F) of the LAA were significantly lower in all patients with ventricular pacing (25.5+/-15.6%, 30.4+/-15.6 cm/s and 29. 1+/-19.2 cm/s, respectively) compared to those with physiologic pacing (48.5+/-16.9%, 59.6+/-16.3 cm/s, 57.9+/-18.5 cm/s, respectively) (P<0.01 in all). When patients were further classified with respect to underlying heart disease whether they had SSS or AVB, all measurements of the LAA (EF, V(E) and V(F)) in both subgroup of patients with SSS and AVB were found significantly lower in those with ventricular pacing than in those with physiologic pacing (Tables 3 and 4). This decrease, especially in LAA flow, was much greater in those with SSS (Mean V(E) and V(F) <20 cm/s). In a patient paced with VVI for SSS, a thrombus was detected within the LAA cavity. In conclusion, these results suggest that the pacing modality appeared to influence the LAA functions in paced patients. Patients with asynchronous ventricular pacing modes had a significantly higher incidence of depressed LAA functions than did patients with physiological pacing, especially more marked in patients with sick sinus syndrome. This may be a factor responsible for increased risk of thrombus formation and thromboembolic events in this patient population.     

Left atrial appendage function during DDD and VVI pacing.

OBJECTIVE: To examine, using transoesophageal echocardiography, the possible disturbances of left atrial appendage function during VVI and DDD pacing in patients with a normal atrium paced with a dual chamber system. DESIGN: Randomised controlled trial. SETTING: Tertiary care centre. PATIENTS: 22 patients (mean age 68 (SD 6) years) who had been paced with dual chamber pacemakers for at least six months. Exclusion criteria were valvar disease, cardiomyopathy, hypertension, and diabetes mellitus. INTERVENTIONS: All patients underwent a transoesophageal echocardiographic evaluation of left atrial appendage function under DDD and VVI modes in random order. Measurements were made after at least two months' pacing in each mode. MAIN OUTCOME MEASURES: Echocardiographic indices of left atrial appendage flow under both pacing modes. RESULTS: All 22 patients had higher emptying and filling flow velocities under DDD than under VVI mode. The filling and emptying flow velocity integrals were also significantly higher under DDD mode (P < 0.001, P = 0.019). CONCLUSIONS: Left atrial appendage function, as reflected in indices of emptying and filling assessed by transoesophageal echocardiography, is significantly different with DDD than with VVI pacing. This may explain the higher incidence of thromboembolic episodes in patients paced under VVI mode.     

病窦综合征患者AAI和VVI起搏的远期随访分析

分析并比较病窦综合征 (SSS)患者AAI和VVI起搏的远期效果。对 1 4 0例AAI起搏、4 3例VVI起搏的SSS患者进行定期随访并行临床、心电图和Holter检查。结果 :随访 5 2± 4 .3(6～ 1 4 4 )个月 ,AAI组发生间歇性文氏型房室阻滞 (AVB) 1例。VVI起搏组阵发性房性心律失常、持续性心房颤动、脑栓塞、心源性死亡的发生率明显较AAI组高(分别为 39.5 3%vs 5 .71 %、1 8.6 0 %vs 1 .4 3%、9.3%vs 0 .71 %、1 1 .6 3%vs 0 .71 % ,P均 <0 .0 1 )。快速房性心律失常的发生率VVI组明显增加 (39.5 3%vs 1 8.6 0 % ,P <0 .0 1 ) ,AAI组明显减少 (5 .71 %vs 1 8.5 7% ,P <0 .0 1 )。无 1例近期和远期电极脱位。结论 :AAI起搏时远期AVB和电极脱位发生率很低 ,并且快速性房性心律失常、脑栓塞、心源性死亡事件的发生率低于VVI起搏     

P wave changes and atrial fibrillation after implantation of VVI type pacemaker]

The P waves of patients with VVI pacemakers were compared with those of DDD pacemakers at implantation and then regularly for 5 years. A certain number of cardiac pathologies are known to cause P wave changes. The incidence of atrial fibrillation (AF) was much higher in VVI than in DDD patients. In the VVI group, the incidence was much greater in patients paced for sinus node disease than in patients paced for AVB. Analysis of sinus P wave characteristics in 320 patients with VVI pacemakers shows progressive abnormalities of atrial function with time. The expression of this atrial dysfunction is a statistically significant prolongation of the P wave in V1 and dII and of the terminal part of the P wave in V1. The factors responsible for this abnormality and which favours the occurrence of AF are quasi-permanent pacing, the presence of retrograde conduction and an abnormality of atrial activation at the time of implantation.     

VVI与DDD起搏对病窦综合征患者远期疗效的比较

比较VVI与DDD起搏方式对病窦综合征患者的临床疗效。研究病窦综合征患者212例,按不同起搏方式分为两组:VVI组105例、DDD组107例。研究终点:①在每次预定的随访中,以标准12导联ECG、Holter及心电监护诊断心房颤动(简称房颤);②卒中:当患者有大于24h脑缺血事件而产生神经系统症状或24h内死于脑血管事件,可确诊为卒中;③死亡:心血管事件死亡。患者出院后1,3,6个月定期随访,以后每隔半年随访一次。随访时,记录标准12导联ECG存档。每例患者至少有一份ECG,部分患者做Holter,了解有无阵发性房颤及术后发生持续性房颤的时间,患者的症状及体征。结果:①与VVI组比较,DDD组房颤发生率明显降低(10.3%vs24.8%,P<0.05);②VVI组患者6例出现脑卒中(5.7%),而DDD组无1人发生脑卒中,两组差异有显著性(P<0.05);③VVI组共有3例在术后3,4年发生慢性充血性心力衰竭,最后死于恶性心律失常,而DDD组患者均无因心力衰竭住院,随访至今无死亡。DDD组11例房颤均在2年内发生,其中第1年7例,而VVI组有26例房颤发生的时间较为弥散,2年内发生8例(30.8%),其余在3~8年内陆续发生。结论:病窦综合征患者安装双腔起搏器治疗发生房颤和脑卒中的机率明显减少。     

房室传导正常的病窦综合征患者心房或心室起搏的长期随访

评价长期心房或心室起搏对病窦综合征 (SSS)患者心功能及房性心律失常的影响 ,对 1 1 8例SSS伴房室传导正常的患者 (AAI组 56例、VVI组 62例 )进行随访。随访 40 .8± 2 .3个月 ,VVI组 62例中 1 9例NYHA分级增加 ,而AAI组 56例中 4例NYHA分级增加 (P <0 .0 5)。左室射血分数VVI组明显下降 (从 0 .491± 0 .0 4 1至 0 .451± 0 .0 4 3 ,P <0 .0 5) ,而AAI组则增加 (从 0 .482± 0 .0 75增至 0 .535± 0 .0 59,P <0 .0 5)。左房内径VVI组明显增加 (从 33± 6增至 40± 6mm ,P <0 .0 5) ,AAI组从 34± 7增至 36± 6(P >0 .0 5)。房性心律失常发生率VVI组明显增加 (从 35 .5 %增至 45 .2 % ,P <0 .0 5) ,AAI组减少 (从 2 6 .8%降至 0 % ,P <0 .0 1 )。结论 :心房起搏对SSS患者是一安全、可靠的起搏方式 ,可减少房性心律失常的发作 ,有助于患者心功能的改善     

不同起搏方式对病窦综合征患者远期效果的影响

为了解不同起搏方式对病窦综合征特别是慢－快综合征患者心功能及房性心律失常的影响，利用超声心动图、体表心电图及Ｈｏｌｔｅｒ检查，对２１１例病窦综合征患者采用自身对照方法进行回顾性分析。结果发现：生理性起搏（ＡＡＩ／ＤＤＤ）组术后左室射血分数（ＬＶＥＦ）、心输出量（ＣＯ）明显增加（ＡＡＩ：５３．５±６．１％ｖｓ４７．２±７．８％，４．９５±０．５７Ｌ／ｍｉｎｖｓ４．２０±０．６２Ｌ／ｍｉｎ；ＤＤＤ：５２．５±６．８％ｖｓ４４．３±０．１％，５．１２±０．７１Ｌ／ｍｉｎｖｓ４．４１±０．３８Ｌ／ｍｉｎ；Ｐ均＜０．０１），左房内径（ＬＡＤ）无明显变化；ＤＤＤ组Ｅ／Ａ比值明显增加（０．９８±０．０９ｖｓ０．８７±０．１５，Ｐ＜０．０１），ＡＡＩ组Ｅ／Ａ比值呈增加趋势（Ｐ＝０．０５７）。房性心律失常发生率明显减少（１５．９％ｖｓ５０％，Ｐ＜０．０１）。非生理性起搏（ＶＶＩ）组术后ＬＶＥＦ、ＣＯ明显下降（４４．１±４．７％ｖｓ４８．３±４．３％，３．７７±０．４２Ｌ／ｍｉｎｖｓ４．１７±０．８５Ｌ／ｍｉｎ，Ｐ均＜０．０１），ＬＡＤ明显增大（３９．２６±２．３７ｍｍｖｓ３６．８１±２．３５ｍｍ，Ｐ＜０．０１），Ｅ／Ａ比值呈?     

High risk of cardiogenic cerebral embolism for very elderly patients in sinus rhythm with left atrial appendage flow velocity below 50 cm/s

Recent clinical trials have demonstrated that patients in sinus rhythm after cardioversion are still at risk of suffering from embolic events, but the precise mechanisms underlying the occurrence of cardiogenic cerebral embolism remain to be determined. All 72 patients aged 75 or over who were consecutively referred to our department between October 2003 and March 2006 were divided into three groups; these were: group 1, 17 patients in sinus rhythm after cardioversion; group 2, 18 patients without any history of atrial fibrillation; and group 3, 37 patients with chronic atrial fibrillation. Using transesophageal echocardiography, we evaluated the left atrial appendage flow velocity, left atrial appendage dimension, spontaneous echocardiographic contrast in the left atrium, and the presence of thrombus in the left atrial appendage. Left atrial appendage flow velocity was significantly lower in group 1 compared with group 2 (38.2 ± 6.1 vs 61.4 ± 7.4 cm/s, P  < 0.001), but was even lower in group 3 (25.1 ± 9.8 cm/s, P  < 0.001 vs group 1). Spontaneous echocardiographic contrast in the left atrium, thrombus in the left atrial appendage and cardiogenic cerebral embolism showed a close relationship with left atrial appendage flow velocity, and were more frequent when left atrial appendage flow velocity was less than 50 cm/s. Very elderly patients in long-term maintenance of sinus rhythm with an left atrial appendage flow velocity of less than 50 cm/s would have a high risk of cardiogenic cerebral embolism.     

Effects of pacing modes on cardiac baroreflex function in permanently paced patients with sinus node dysfunction

Objectives: We compared, in patients with sick sinus syndrome, the effects of various pacing modes on baroreceptor (BR)-stroke volume (SV) reflex sensitivity, a method we have closely correlated with BR-heart rate (HR) reflex sensitivity.
Background: Impaired autonomic nervous function, such as decreased BR-HR reflex sensitivity, predicts sudden cardiac death. However, in patients with sick sinus syndrome, the effects of various pacing modes on autonomic function are unknown, since chronotropic incompetence precludes its evaluation by measurements of BR-HR reflex sensitivity.
Methods: We studied 12 recipients of dual-chamber pacemakers with sick sinus syndrome (mean age = 73 ± 8 years; 8 men). Beat-by-beat blood pressure (BP) and SV were measured during 5-minute runs of AAI, DDD, and VVI pacing, and spectrally analyzed to assess BR-SV reflex sensitivity.
Results: Systolic BP was significantly lower (P < 0.01) during VVI (109 ± 24 mmHg) than during DDD (124 ± 22 mmHg) or AAI (125 ± 41 mmHg) pacing. SV was significantly smaller during VVI (36 ± 23 mL) than during DDD (49 ± 31 mL) pacing (P < 0.05). BR-SV reflex sensitivity was significantly lower (P < 0.05) during VVI (9.3 ± 5.7% per mmHg) than during DDD (15.0 ± 6.5% per mmHg) or AAI (15.5 ± 6.2% per mmHg) pacing.
Conclusions: BR-SV reflex sensitivity was significantly lower during VVI than during AAI or DDD pacing. Atrioventricular synchrony plays an important role in the preservation of BR-SV reflex sensitivity in pacemaker recipients.     

Benefits of dual chamber pacing in sick sinus syndrome

The effects of DDD (fully automatic) and VVI (ventricular demand) pacing modes on exercise tolerance, symptom diary cards, and Holter monitoring were investigated in a randomised double blind crossover study of 16 patients who had had DDD pacemakers implanted because of frequent syncope. Eight patients presented with sick sinus syndrome and, with one exception, retrograde atrioventricular conduction and eight age and sex matched patients presented with 2:1 or complete atrioventricular block. Maximal symptom limited exercise in those with atrioventricular block was significantly higher after one month of DDD pacing than after VVI pacing. In those with sick sinus syndrome, however, maximal effort tolerance was not significantly different for the two pacing modes. In all but one patient with sick sinus syndrome sinus rhythm developed during exercise in VVI pacing. For both VVI and DDD modes maximal atrial rates were significantly lower in those with sick sinus syndrome. Palpitation and general wellbeing were significantly improved during DDD pacing in the eight patients with sick sinus syndrome. Shortness of breath was improved by DDD pacing in the eight patients with atrioventricular block but not in those with sick sinus syndrome. Holter monitoring showed that sick sinus syndrome patients remained in paced rhythm, either DDD or VVI, for most of the 24 hour period. DDD pacing was better than VVI pacing in sick sinus syndrome with retrograde atrioventricular conduction. Despite their ability to show sinus rhythm and inhibit their pacemakers on exercise patients with sick sinus syndrome are just as likely to have symptomatic benefit from DDD pacing as patients with atrioventricular block.     

Atrial Mechanical Function Before and After Electrical or Amiodarone Cardioversion in Atrial Fibrillation: Assessment by Transesophageal Echocardiography and Pulsed Doppler

In some patients with atrial fibrillation (AF), it has been suggested that left atrial mechanical dysfunction can develop after successful electrical cardioversion, justifying postcardioversion anticoagulant treatment. The purpose of this study was to investigate differences in left atrial appendage peak flow velocities and the incidence of left atrial spontaneous echo contrast in patients with AF before and after electrical cardioversion or intravenous amiodarone, studied using transesophageal echocardiography (TEE) and pulsed Doppler. We performed a control TEE in 7 patients in the electrical group and 6 in the amiodarone group, with no significant clinical differences between both groups. A second TEE was performed immediately in the 7 patients with successful electrical cardioversion. The peak flow velocities in the appendage before and after the procedure were: filling 43.3 ± 22 vs 27.7 ± 28 cm/sec (P = 0.01) and emptying 35.5 ± 22 vs 23.6 ± 17 cm/sec (P = 0.01), respectively. The spontaneous echo contrast increased in 4 of the 7 patients. In 4 patients of the amiodarone group, the peak flow velocities in the appendage during AF and within the first 24 hours after restoration of sinus rhythm were: filling 37.4 ± 12 vs 37.8 ± 18 cm/sec and emptying 36.4 ± 18 vs 35.9 ± 18 cm/sec, respectively (P = NS). There was no change in spontaneous echo contrast. In conclusion, patients with AF reverted to sinus rhythm using amiodarone did not show changes in left atrial mechanical function; however, patients with electrical cardioversion showed mechanical dysfunction. Further investigations on the effects of amiodarone and other drugs on the mechanical function of the atria are needed to determine if patients reverted pharmacologically require antico-agulation post reversion.     

Benefits of dual chamber pacing in sick sinus syndrome.

The effects of DDD (fully automatic) and VVI (ventricular demand) pacing modes on exercise tolerance, symptom diary cards, and Holter monitoring were investigated in a randomised double blind crossover study of 16 patients who had had DDD pacemakers implanted because of frequent syncope. Eight patients presented with sick sinus syndrome and, with one exception, retrograde atrioventricular conduction and eight age and sex matched patients presented with 2:1 or complete atrioventricular block. Maximal symptom limited exercise in those with atrioventricular block was significantly higher after one month of DDD pacing than after VVI pacing. In those with sick sinus syndrome, however, maximal effort tolerance was not significantly different for the two pacing modes. In all but one patient with sick sinus syndrome sinus rhythm developed during exercise in VVI pacing. For both VVI and DDD modes maximal atrial rates were significantly lower in those with sick sinus syndrome. Palpitation and general wellbeing were significantly improved during DDD pacing in the eight patients with sick sinus syndrome. Shortness of breath was improved by DDD pacing in the eight patients with atrioventricular block but not in those with sick sinus syndrome. Holter monitoring showed that sick sinus syndrome patients remained in paced rhythm, either DDD or VVI, for most of the 24 hour period. DDD pacing was better than VVI pacing in sick sinus syndrome with retrograde atrioventricular conduction. Despite their ability to show sinus rhythm and inhibit their pacemakers on exercise patients with sick sinus syndrome are just as likely to have symptomatic benefit from DDD pacing as patients with atrioventricular block.     

Dual chamber pacing: how many patients remain in DDD mode over the long term?

OBJECTIVE--DDD pacing is better than VVI pacing in complete heart block and sick sinus syndrome but is more expensive and demanding. In addition, some patients have to be programmed out of DDD mode and this may have an important impact on the cost-effectiveness of DDD pacing. The purpose of this study was to determine how many patients remain in DDD mode over the long term (up to 10 years). DESIGN--A retrospective analysis of the outcome over 10 years of consecutive patients who had their pacemakers programmed initially in DDD mode. SETTING--A district general hospital. PATIENTS--249 patients with DDD pacemakers. Sixty two patients (24.9%) had predominantly sick sinus syndrome and 180 (72.3%) had predominantly atrioventricular conduction disease. Mean (range) complete follow up for this group of patients was 32 months (1-10 years). RESULTS--Cumulative survival of DDD mode was 83.5% at 60 months. Atrial fibrillation was the commonest reason for abandonment of DDD pacing. Atrial fibrillation developed in 30 patients (12%), with atrial flutter in three (1.2%). Loss of atrial sensing or pacing, pacemaker mediated tachycardia, and various other reasons accounted for reprogramming out of DDD mode in eight patients (3.2%). Overall, an atrial pacing mode was maintained in 91% and VVI pacing was needed in only 9%. CONCLUSIONS--With careful use of programming facilities and appropriate secondary intervention, most patients with dual chamber pacemakers can be maintained successfully in DDD or an alternative atrial pacing mode until elective replacement, although atrial arrhythmia remains a significant problem. There are no good reasons, other than cost, for not using dual chamber pacing routinely as suggested by recent guidelines and this policy can be achieved successfully in a district general hospital pacing centre.     

Selecting the Appropriate Pacing Mode for Patients with Sick Sinus Syndrome: Evidence from Randomized Clinical Trials

Several observational studies have indicated that selection of pacing mode may be important for the clinical outcome in patients with symptomatic bradycardia, affecting the development of atrial fibrillation (AF), thromboembolism, congestive heart failure, mortality and quality of life. In this paper we present and discuss the most recent data from six randomized trials on mode selection in patients with sick sinus syndrome (SSS). In pacing mode selection, VVI(R) pacing is the least attractive solution, increasing the incidence of AF and-as compared with AAI(R) pacing, also the incidence of heart failure, thromboembolism and death. VVI(R) pacing should not be used as the primary pacing mode in patients with SSS, who haven't chronic AF. AAIR pacing is superior to DDDR pacing, reducing AF and preserving left ventricular function. Single site right ventricular pacing-VVI(R) or DDD(R) mode-causes an abnormal ventricular activation and contraction (called ventricular desynchronization), which results in a reduced left ventricular function. Despite the risk of AV block, we consider AAIR pacing to be the optimal pacing mode for isolated SSS today and an algorithm to select patients for AAIR pacing is suggested. Trials on new pacemaker algorithms minimizing right ventricular pacing as well as trials testing alternative pacing sites and multisite pacing to reduce ventricular desynchronization can be expected within the next years.     

Conduction Velocity in the Tricuspid Valve-Inferior Vena Cava Isthmus is Slower in Patients With Type I Atrial Flutter Compared to Those Without a History of Atrial Flutter

Slower Conduction in the TV-IVC Isthmus. Introduction : In human type I atrial flutter, the electrophysiologic substrate is unclear. In order to determine if slow conduction is mechanistically important, we evaluated conduction velocity in the tricuspid valve-inferior vena cava (TV-IVC) isthmus, right atriai free wall, and interatrial septum in patients with and without a history of atrial flutter undergoing electrophysiologic study.
Methods and Results : Nine patients with (group 1) and nine without a history of type I atrial flutter (group 2) were studied. Conduction time (msec) in the right atrial free wall. TV-IVC isthmus (bidirectional), and interatrial septum was measured during pacing in sinus rhythm at cycle lengths of 600, 500, 400, and 300 msec from the low lateral right atrium and coronary sinus ostium. Conduction velocity (cm/sec) was calculated by dividing the distance between pacing electrodes and sensing electrodes (cm) by the conduction time (sec). Conduction velocity was slower in the TV-IVC isthmus in group 1 (range 37 ± 8 to 42 ± 8 cm/sec) versus group 2 (range 50 ± 8 to 55 ± 9 msec) at all pacing cycle lengths (P < 0.05). However, conduction velocity was not different in the right atrial free wall or interatrial septum between groups 1 and 2. Conduction velocity was also slower in the TV-IVC isthmus than in the right atrial free wall and interatrial septum in group 1 patients, at all pacing cycle lengths (P < 0.05). Atrial flutter cycle length correlated with total atrial conduction time (r ≥ 0.832, P < 0.05).
Conclusion : Slow conduction in the TV-IVC isthmus may be mechanistically important for the development of human type I atrial flutter.     

不同起搏方式对心房电机械延迟影响的对比研究

了解双腔起搏 (DDD)患者右心耳起搏 (RAA)方式对心房电机械延迟 (AEMD)的影响。对 2 1例置入DDD的患者 ,用M型超声心动图结合同步心电图分别测量DDD方式及心房感知心室起搏 (VDD)方式下的AEMD。结果 :RAA起搏与窦性节律比较 ,AEMD明显增加 ,其中P波起始至中央纤维体 (CFB)运动发生的时间增加 2 8± 4ms、至CFB最大收缩振幅出现的时间增加 42± 3ms、至左房侧壁 (LLA)运动发生的时间增加 35± 5ms、至LLA最大收缩振幅出现的时间增加 34± 4ms (所有P <0 .0 0 1)。结论 :DDD患者右心耳起搏能明显增加AEMD     

埋藏式心脏起搏器治疗病态窦房结综合症130例临床总结

目的:探讨在病态窦房结综合征(SSS)患者起搏治疗中各种起搏模式的比例及对患者临床预后的影响。方法:对我院130例行起搏器安装术SSS患者的资料,进行起搏模式及临床预后分析。结果:130例患者中生理性起搏(AAI／DDD)占27.6％,其中AAI起搏占11.2％,DDD起搏占16.4％;心室按需型起搏(VVI)占72.4％。植入起搏器能明显改善SSS患者的临床症状,在生理性起搏组中永久性房颤、心衰的发生率以及患者死亡率均明显低于非生理性起搏组(P<0.05~<0.01),手术并发症发生率为10.8％,主要并发症为电极脱位和感知障碍。结论:生理性起搏是治疗SSS较理想的起搏方式,但目前应用的比例仍偏低。     

Relationship with plasma neurohormones and dyssynchrony detected by Doppler echocardiography in patients undergoing permanent pacemaker implantation

OBJECTIVE: To determine whether isovolumic relaxation flow (IRF) and isovolumic contraction flow (ICF) resulted from asynchrony and asynergy due to VVI and DDD pacemakers modulated neurohormones, we measured neurohormone levels in plasma and investigated the characteristics of IRF and ICF using Doppler echocardiography. METHODS AND RESULTS: We studied 11 patients with dual-chamber pacemakers (DDD) and 11 patients, with ventricular inhibiting mode (VVI). All patients underwent Doppler echocardiography of the left ventricle. Atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), renin and aldosteron were measured. The LV was scanned for the presence of intracavitary flow during the isovolumic relaxation and isovolumic contraction period. The plasma levels of BNP and ANP were significantly lower in DDD mode than in VVI mode (56 +/- 32 pg/ml vs. 94 +/- 32 pg/ml, p = 0.022 and 98 +/- 20 pg/ml vs. 134 +/- 17 pg/ml, p = 0.042, respectively). There were no significant differences in the plasma level of renin or aldosteron. VVI mode versus DDD mode increased isovolumic relaxation flow time (129 +/- 41 vs. 111 +/- 36 sec, p = 0.020) and isovolumic relaxation flow velocity (50 +/- 4 vs. 37 +/- 2 cm/s, p = 0.018). A strong relationship between blood ANP and BNP levels and IRF velocity was found in patients with a VVI pacemaker (r: 0.632, p: 0.028; r: 0.528, p: 0.024, respectively). CONCLUSION: VVI mode has a longer isovolumic relaxation time, isovolumic relaxation flow velocity and has higher ANP and BNP plasma levels than DDD mode. IRF resulting from asynergy and asynchrony in VVI mode pacemakers versus DDD mode pacemakers affects the plasma levels of ANP and BNP compared to renin and aldosteron.     

起搏术后心房颤动的影响因素及心房颤动与心钠素的关系

目的观察心脏起搏术后发生心房颤动(简称房颤)的影响因素及房颤与血心钠素(ANP)的关系。方法选择安装心脏起搏器的患者103例进行随访,分析房颤与年龄、起搏方式、心律失常类型、左房内径(LAD)、左室射血分数(LVEF)和血ANP的关系。结果①65岁以下患者房颤发生率低于65岁以上组(P<0.05)。②VVI组房颤发生率高于DDD组(P<0.05)。③慢快综合征组房颤发生率较缓慢型病窦综合征和房室传导阻滞组高(P<0.05)。④VVI房颤组术后LAD增大、LVEF下降(P<0.05),VVI房颤组术后与DDD组比较有差异(P<0.05)。⑤VVI房颤组和VVI窦性心律组ANP浓度较DDD组高(P<0.05);各组不同心功能级别(NYHA)之间ANP浓度随着心功能级别的加重而升高。结论长期心脏起搏术后房颤的发生可能与年龄大、VVI起搏、病窦综合征(慢快型)、LAD增大、LVEF降低及ANP浓度升高相关。     

不同起搏模式对病态窦房结综合征患者心功能长期影响的探讨

目的前瞻性观察不同起搏模式对心功能长期的影响并探讨可能机制。方法 185例病态窦房结综合征（SSS）患者均采用常规方法经锁骨下静脉途径成功置入永久双腔心脏起搏器,术后即刻程控起搏器,根据SAS软件的PROC程序产生一组随机序列分为AAI（92例）及DDD（93例）起搏组。采用心脏超声观察术前,术后1、2、5年左室舒张末容积（LVEDV）、左室收缩末容积（LVESV）及左室射血分数（LVEF）的变化,比较两种起搏模式对左心功能的影响;术后1、2及5年进行随访结合起搏器程控记录房颤发生并记录DDD起搏组右室起搏百分比（VP%）,探讨VP%与心功能变化及房颤发生的关系。结果 AAI起搏组术前,术后1、2、5年随访LVEDV,LVESV及LVEF比较差异无统计学意义（P〉0.05）,DDD起搏组术前、术后1、2、5年LVEDV差异无统计学意义（P〉0.05）,术后5年LVESV（60.33±13.28）ml较术后1、2年增加,差异有统计学意义（F=2.7388,P〈0.05）,术后5年LVEF（41.75±8.74）%较术前、术后1、2年明显降低,差异有统计学意义（F=33.4393,P〈0.05）;AAI组与DDD组房颤的发生差异有统计学意义（P〈0.05）。术后5年DDD组中〈50%VP%,组中出现房颤患者为3例,≥50%VP%组中出现房颤患者为15例,两组之间房颤的发生率差异有统计学意义（P〈0.05）。结论在DDD起搏模式下,高的VP%可对患者的左心功能造成损害并增加房颤的发生。对于不合并房室传导阻滞的SSS患者,AAI起搏较DDD起搏能使患者更受益。