The left atrial function index: a rhythm independent marker of atrial function.

AIMS: This study evaluates a simple echocardiographic rhythm independent expression of left atrial (LA) function, 'the left atrial function index' (LAFI). BACKGROUND: Quantitation of LA function is challenging and often established parameters including peak A are limited to sinus rhythm (SR). We hypothesized that atrial function could be characterized independent of rhythm by combining analogues of LA volume, reservoir function and LV stroke volume. METHODS: Seventy-two patients with chronic atrial fibrillation (CAF) were followed for six months post cardioversion (CV). Thirty-seven age matched healthy subjects were controls. The LAFI = LAEF x LVOT-VTI/LAESVI (LAEF = LA emptying fraction, LAESVI = maximal LA volume indexed to BSA, LVOT-VTI = outflow tract velocity time integral). RESULTS: The LAFI pre-CV in the CAF group was depressed vs controls (0.10 +/- 0.05 vs 0.54 +/- 0.17; P = 0.0001). Post-CV, LAFI was lower in persistent AF than in those restored to SR (AF vs SR: 0.08 +/- 0.03 vs 0.15 +/- 0.08; P = 0.0001), improved progressively in SR and was unchanged when AF persisted. CONCLUSION: The LAFI, a simple, rhythm independent expression of atrial function, appears sensitive to differences between individuals in AF and those restored to SR and justifies clinical and investigative applications.     

Extended distribution of prolonged and fractionated right atrial electrograms predicts development of chronic atrial fibrillation in patients with idiopathic paroxysmal atrial fibrillation

INTRODUCTION: This study evaluates whether electrophysiologic abnormalities in patients with idiopathic paroxysmal atrial fibrillation (PAF) predict the transition to chronic atrial fibrillation (CAF). METHODS AND RESULTS: Ninety-six patients with idiopathic PAF underwent electrophysiologic study and were followed up. During electrophysiologic study, endocardial mapping was performed at 12 sites in the right atrium (four aspects of the high, middle, and low right atrium). During follow-up of 60 to 130 months, conversion from PAF to CAF was observed in 17 patients (CAF group). The remaining 79 patients remained in sinus rhythm (PAF group). Although a high frequency of abnormal atrial electrograms was observed in the high right atrium in both groups, the frequency of those recorded from the middle right atrium was significantly higher in the CAF group than in the PAF group (70.6% vs 13.9%, P < 0.0005). Kaplan-Meier analysis showed that >50% of the patients with abnormal atrial electrograms in the middle right atrium developed CAF after 10 years, whereas only 7% of patients without those developed CAF (P < 0.0001). CONCLUSION: Our data suggest that extended distribution of abnormal atrial electrograms from the high to middle right atrium is predictive of the development of CAF in patients with idiopathic PAF.     

慢性心房颤动患者左心房扩大与左心房血栓形成的相关性

目的:探讨慢性心房颤动患者左心房扩大与左心房血栓形成的相关性。方法:选择我院确诊的80例慢性心房颤动伴左心房扩大患者为左心房扩大组,80例慢性心房颤动左心房无扩大患者为心房无扩大组,应用经食管超声检测左心房大小及观察有无血栓。根据食管超声检查结果分为血栓形成组(22例)和无血栓组(138例),通过单因素及多元逐步Logistic回归分析,分析左心房血栓形成的危险因素。结果:超声心动图显示左心房扩大组心房内血栓形成率明显高于左心房无扩大组(17.5%比10.0%,P<0.05)。多因素Logistic回归分析显示,与心房内血栓形成的相关的危险因素有:左心房直径(OR=4.514,95%CI:1.243～14.206,P=0.01)、病程(OR=1.106,95%CI:0.898～1.071,P=0.035)。结论:心房颤动患者的左心房扩大,可导致心肌收缩力下降,增加左心房内血栓形成的危险性,是左心房内血栓形成的有意义的预测因子。     

Left and right atrial volume by freehand three-dimensional echocardiography: in vivo validation using magnetic resonance imaging.

INTRODUCTION: Measurement of left and right atrial size is important for the management of arrhythmias, valvular and congenital heart disease. We have demonstrated that freehand three-dimensional (3D) echocardiography is more accurate and reproducible than two-dimensional (2D) echocardiography for measurement of left ventricular mass and volume. However, no prior study has validated the accuracy of freehand 3D for the determination of left or right atrial volume. METHODS: End-systolic (maximum) left and right atrial volumes were determined in 21 volunteer patients and normal subjects by one, two, and freehand 3D transthoracic echocardiography and compared to volumes obtained by gradient recalled magnetic resonance imaging. Three-dimensional echocardiographic determination of atrial volume was obtained using an acoustic spatial locator, a line-of-intersection display, and a surface reconstruction algorithm. Two-dimensional echocardiographic atrial volumes were obtained from apical biplane images of the left atrium and an apical single plane image of the right atrium using a summation of disks method. One-dimensional (ID) estimates of left atrial volume were determined by cubing the M-mode ID antero-posterior dimension obtained on the parasternal long axis view. RESULTS: An excellent correlation was Obtained between freedhand 3D echocardiography and magnetic resonce imaging (MRI) for the left atrium (r = 0.90, SEE=9.6 ml) and for the right atrium (r = 0.91, SEE = 8.8 ml) with a small bias (left atrium 5.25 ml, right atrium 12.06 ml) and narrow limits of agreement (left atrium 22.14 ml, right atrium 25.54 ml). Two-dimensional echocardiography correlated less well (left atrium r = 0.87, SEE = 10.23 ml, right atrium r = 0.79, SEE = 19.74 ml), and had a higher bias (left atrium 14.46 ml, right atrium 8.99 ml) and larger limits of agreement (left atrium 24.37 ml, right atrium 41.16 ml). One-dimensional estimates of left atrial volume correlated poorly with magnetic resonance determined left atrial volume (r = 0.80, SEE = 6.61 ml) and had unacceptably high bias (45.09 ml) and limits of agreement (35.52 ml). Interobserver variability was lowest for 3D echocardiography (left atrium 7.2 ml, 11%, right atrium 8.7 ml, 16%). CONCLUSIONS: Freehand 3D echocardiography using the line of intersection display for guidance of image positioning and a polyhedral surface reconstruction algorithm is a valid, accurate, reproducible method for determining left and right atrial volume in humans that is comparable to magnetic resonance imaging and is superior to current ID and 2D echocardiographic techniques.     

心房颤动射频消融术后继发房性心律失常的机制和对策

目的 研究心房颤动(AF)患者环肺静脉射频消融术后继发房性快速性心律失常(ATA)的机制和对策.方法 继发ATA 15例.左房各肺静脉逐一标测,对恢复心房-肺静脉传导的静脉补点消融,达到心房-肺静脉电隔离.成功后仍然存在或诱发ATA的则进行CARTO激动标测和拖带标测,并行辅线消融或局灶消融,直到不能诱发.结果 经电生理标测发现14例恢复了心房-肺静脉传导.相应补点消融后电隔离,9例不能再诱发,3例诱发了左房大折返心动过速,左房顶部/峡部消融后终止,1例诱发左房局灶心动过速,局灶消融后成功.2例诱发右房大折返心动过速,右房峡部消融后消失.术后随访1～16(5.5±4.4)个月,13例无复发,2例发作明显减少.结论 左房-肺静脉传导恢复是继发ATA的重要机制;其他机制还包括左房顶部、峡部、右房峡部依赖的大折返心动过速以及局灶房性心动过速等.对继发ATA,先检查肺静脉并补点消融很重要,但不能完全解决问题,尚需根据CARTO激动标测和拖带标测进行个体化的消融.     

心房肌缝隙连接蛋白40、43表达改变与心房颤动的关系

目的：研究心房颤动患者心房肌缝隙连接蛋白(Cx)40、43表达的改变，探讨Cx在房颤发生与维持中的作用。方法：39例接受开胸手术者分为房颤组和窦性心律组，手术时取右心耳及左心房各约100mg，采用Western blot与免疫组织化学技术，检测心房肌Cx40、Cx43表达量与分布的改变。结果：房颤组Cx40表达量在左心房、右心耳较窦性心律组高，Cx43表达量在左心房较窦性心律组高，在右心耳无差异。免疫组化显示房颤组Cx40、Cx43均分布紊乱，聚集于胞浆或核周。结论：房颤患者心房肌Cx40、Cx43表达增高，且分布异常，提示心房肌Cx40、Cx43表达改变与心房颤动的发生与维持有关。     

不纯心房扑动发生机制的心内电生理探讨

目的：心内电生理检查研究体表心电图不纯心房扑动的可能发生机制。方法6例患者经体表心电图证实有不纯心房扑动,射频消融时进行了心内电生理检查,并进行峡部阻断法消融心房扑动。结果：体表心电图与心心内电图同步记录证实,6例不纯心房扑动发作时均为右心房扑动、左心房颤动的心房脱节,心房扑动射频消融均获成功。随访期中2例复发,再次消融成功。结论：不纯心房扑动的发生可能是在右心房扑动的同时,左心房发生一过性颤动的结果。     

氯通道ClC-1、ClC-2在人心房肌的表达及与心房颤动的关系

目的研究氯通道ClC-1和ClC-2基因在人心房组织的表达及与心房颤动(AF)的关系。方法将71例风湿性心瓣膜病接受换瓣手术患者分为三组,窦性心律(SR)组31例,阵发性房颤(PAF)组7例,慢性房颤(CAF)组33例,于术中获取右心耳组织,应用半定量逆转录-聚合酶链反应(RT-PCR)检测心房组织ClC-1和ClC-2的mR-NA相对含量。结果①ClC-1、ClC-2基因在人心房组织有表达。②与SR组比较,PAF组ClC-1的mRNA表达增加但无统计学意义(1.05±0.22vs1.01±0.13,P>0.05),CAF组的表达明显增加(1.25±0.18vs1.01±0.13,P<0.001),CAF组较PAF组亦明显增加(P<0.01)。ClC-1的mRNA表达水平与左房内径、AF持续时间呈正相关[(r=0.344,P=0.003)(r=0.405,P<0.001)]。③与SR组比较,PAF组ClC-2的mRNA表达无增加(1.03±0.14vs1.04±0.15,P>0.05),CAF组的表达明显增加(1.26±0.13vs1.04±0.15,P<0.001),CAF组较PAF组亦明显增加(P<0.01)。ClC-2的mRNA表达与左房内径、AF持续时间呈正相关[(r=0.441,P<0.001)(r=0.331,P=0.005)]。结论AF患者ClC-1、ClC-2的mRNA表达水平的增加可能是心房肌电重构的分子基础。     

右心耳M2和M3受体重构与左心房扩张和心房颤动关系的比较研究

目的探讨M受体重构与左房扩张和心房颤动的关系。方法取57例开胸手术患者的右心耳组织（19例窦性心律、28例风湿性二尖瓣狭窄、10例慢性房颤），Western—blot技术检测M2和M3受体的表达。结果风湿性二尖瓣狭窄和慢性房颤患者明显比窦性心律患者的左心房大（P〈0．05）；M2受体在风湿性二尖瓣狭窄引起的左心房扩张和慢性房颤患者心耳的表达明显低于窦性心律患者（0．54±0．08和0．29±0．06，0．26±0．05和0．28±0．06，P〈0．05），而M3受体在风湿性二尖瓣狭窄引起的左心房扩张和慢性房颤患者心耳的表达明显高于窦性心律患者（0．07±0．01和0．18±0．02，0．17±0．01和0．15±0．01，P〈0．05）。在风湿性二尖瓣狭窄患者中，M2和M3受体在窦性心律和房颤患者之间没有明显差别。结论M2和M3受体重构与左心房扩张有关，而与房颤无关。     

Right atrial appendage thrombosis in atrial fibrillation: its frequency and its clinical predictors

This study assesses the incidence of right atrial (RA) chamber and appendage thrombosis in patients with atrial fibrillation (AF) in relation to RA appendage morphology and function. Transthoracic and multiplane transesophageal echocardiography were performed in 102 patients with AF to assess the incidence of RA and left atrial (LA) thrombi and spontaneous echo contrast. Both right and left ventricular sizes, atrial chamber and appendage sizes and function were measured. Twenty-two patients in sinus rhythm served as the control group (SR). Complete visualization of the RA appendage was feasible in 90 patients with AF. Patients with AF had lower tricuspid annular excursion (p = 0.008) and larger RA chamber area (p = 0.0001) than patients in SR. In addition, RA appendage areas were larger (p <0.05) and RA ejection fraction and peak emptying velocities (both p <0.0001) were lower in patients with AF patients than in those in SR. Equivalent differences were found for the LA appendage. Six thrombi were found in the RA appendage and 11 thrombi in the LA appendage in AF patients. Spontaneous echo contrast was found in 57% and 66% in the right atrium and in the left atrium, respectively. AF patients with RA appendage thrombi had a larger RA area (p = 0.0001), and lower RA appendage ejection fraction and emptying velocities (both p = 0.0001) than patients without thrombi. Spontaneous echo contrast was detected in all patients with thrombi. Spontaneous echo contrast was the only independent predictor of RA (p = 0.03) and LA appendage thrombosis (p = 0.036). In conclusion, multiplane transesophageal echocardiography allows the assessment of RA appendage morphology and function. RA spontaneous echo contrast is the only independent predictor of RA appendage thrombosis.     

Stepwise linear approach to catheter ablation of atrial fibrillation

BACKGROUND: This study attempted to convert atrial fibrillation (AF) to sinus rhythm using a stepwise linear catheter ablation approach. METHODS: One hundred and ninety-six patients (43 with persistent AF) were enrolled in the study. A multiple electrode array was used for anatomical navigation and activation mapping. Continuously incremental stimulation was used to induce AF if spontaneous AF was not present. Stepwise linear ablation was applied until AF was converted to sinus rhythm or atypical atrial flutter (AAFL) or atrial tachycardia (AT). The stepwise approach initially utilized a figure-7 lesion line between the right and left superior pulmonary vein on the roof of the left atrium and then extended along the ridge between the left appendage and the left pulmonary veins until the mitral valve annulus, as the primary lesions. If AF still persisted, high-frequency potentials in the inferior left atrium, coronary sinus, or right atrium were targeted. Noninducibility of AF was used as the end point. RESULTS: AF was converted to sinus rhythm in 81.6% of patients (90.8% of paroxysmal and 51.1% of persistent AF, P<.01). The remainders of patients were converted to AAFL or AT. AF was terminated after ablation in right atrium in 7 patients. During an 18.2+/-7.3 month follow-up, 88.3% of patients were free of atrial tachyarrhythmias without medication, 9.7% of patients had refractory AAFL/AT, and only 2.1% of patients had paroxysmal AF. CONCLUSION: Stepwise linear ablation is effective in converting AF to sinus rhythm and the figure-7 lesion line should be the basic lesion. Right atrium ablation is necessary in some patients.     

逐级消融在非阵发性心房颤动中的临床应用

目的 总结三维标测系统(CARTO)指导下逐级消融策略治疗非阵发性心房颤动(房颤)的临床效果及可能机制.方法 40例非阵发性房颤患者接受逐级消融手术,第一步行环肺静脉前庭电学隔离术(PVAI),未复律者继续行线性消融,仍未复律者再继续行碎裂电位消融,直至复律或电复律.术后随访6～18个月.结果 40例患者PVAI后有11例转为窦性心律,线性消融后11例转为窦性心律,碎裂电位消融后6例转为窦性心律,其余行电复律.术后复发4例房颤,2例心房扑动,3例房性心动过速,以单纯PVAI后明显.结论 三维标测系统指导下采用逐级消融策略治疗非阵发性房颤是安全可靠的;单纯PVAI,成功率低,且易复发.     

慢性心房颤动患者血清醛固酮水平与胶原合成血清学标志相关

目的探讨慢性心房颤动(简称房颤)患者血清醛固酮水平与胶原合成的血清学标志之间的相关性。方法收集72例慢性房颤患者(房颤组)及50例窦性心律患者(对照组)。用放射免疫法测定血清醛固酮水平,用酶联免疫吸附分析法测定血清Ⅰ型胶原羧基端前肽(Ⅰ型CP)及Ⅲ型胶原前多肽(Ⅲ型NP)的水平。结果房颤组血清Ⅰ型CP水平显著高于对照组(P<0.01),伴左房扩大的房颤患者Ⅰ型CP水平更高(P<0.01),并且血清Ⅰ型CP水平与左房内径呈正相关。两组受试者中血清Ⅲ型NP水平无显著差别。与对照组相比,房颤组血清醛固酮水平显著增高(P<0.01),伴左房扩大的房颤患者醛固酮水平更高。血清醛固酮水平与左房内径及血清Ⅰ型CP水平呈正相关。结论慢性房颤患者血清醛固酮升高,并与血清Ⅰ型CP水平呈正相关,提示过高的醛固酮水平可能参与心房纤维化形成及房颤的维持。     

Mechanisms of recurrent atrial fibrillation after pulmonary vein isolation by segmental ostial ablation

OBJECTIVES: The aim of this study was to determine the mechanisms responsible for recurrent atrial fibrillation (AF) after pulmonary vein isolation (PV) by segmental ostial ablation. BACKGROUND: Recovery of conduction into a previously isolated PV is a common observation when there is recurrent AF soon after segmental ostial ablation. However, the mechanisms of recurrent AF have been unclear. METHODS: A repeat ablation procedure was performed in 50 patients who had recurrent paroxysmal AF at a mean of 7 +/- 6 months after segmental ostial ablation to isolate the PVs. During the repeat procedure, a ring catheter was inserted into each PV during sinus rhythm and AF to determine whether the veins were still isolated and, if not, whether there were PV tachycardias with a cycle length shorter than in the adjacent left atrium during AF. RESULTS: There was recovery of conduction over a previously ablated muscle fascicle in >/=1 PV in 49 patients (98%). There were 10 +/- 2 episodes of PV tachycardia per minute in 36 (72%) of the 50 patients during AF. Repeat ablation was performed by segmental ostial ablation (23 patients) or by left atrial catheter ablation to encircle the left- and right-sided PVs 1 to 2 cm from the ostia, with additional ablation lines in the posterior left atrium and mitral isthmus (27 patients). At 6-month follow-up, among 23 patients who underwent repeat ablation by segmental ostial ablation, AF recurred in 4 (21%) of the 19 patients who had PV tachycardias and in 3 (75%) of the 4 patients who did not (P = .03). Among the 27 patients who underwent left atrial ablation, AF recurred in 2 (12%) of the 17 patients who had PV tachycardias and in 1 (10%) of the 10 patients who did not (P = 0.7). CONCLUSIONS: Recovery of conduction in previously ablated muscle fascicles is a common finding in patients with recurrent AF after segmental ostial ablation. The efficacy of repeat segmental ostial ablation depends on the presence of PV tachycardias, whereas left atrial ablation is effective regardless of whether PV tachycardias are present or not during AF.     

心房颤动患者心房组织囊性纤维化跨膜转运调节体氯通道基因表达

目的探讨心房颤动(简称房颤)患者心房组织囊性纤维化跨膜转运调节体(CFTR)氯通道基因的表达。方法应用半定量逆转录多聚酶链反应(RT-PCR)比较窦性心律(SR)组(n=31)、阵发性房颤(PAF)组(n=7)和慢性房颤(CAF)组(n=33)患者心房组织CFTR氯通道基因的表达。结果与SR组相比,PAF组CFTR的mRNA表达有增加但未达到统计学意义(P>0.05),CAF组的表达明显增加,CAF组较PAF组亦明显增加(1.20±0.12 vs1.08±0.18,P<0.05)。CFTR的mRNA表达与左房内径呈正相关(r=0.312,P=0.008)。结论慢性房颤患者心房组织CFTR氯通道基因表达上调,可能在房颤心房电重构中起作用。     

递进式个体化心房基质消融治疗心房颤动

目的 以肺静脉电学隔离为终点的心房颤动（房颤）消融术式的疗效难以令人满意。本研究旨在探索规范化的递进式个体化心房基质改良消融术治疗房颤的方法。方法 124例患者（男性96例,女性28例）,年龄27-76（53．6±8．7）岁。其中92例为阵发性房颤,32例为持续性／永久性房颤。若无自发房颤则在心房进行持续递增的快速刺激（频率200—600次／min）诱发房颤。均在非接触式标测观察房颤时心房激动情况,将最常激动部位做为房颤基质进行改良消融,并根据消融后重复等电位标测的结果作出递进式调整,直至房颤被终止不再被诱发。结果 在既不隔离肺静脉也不寻求碎裂电位的情况下,87．1％（108／124）的房颤消融转复为窦性心律,其余被转为非典型心房扑动（房扑）或房性心动过速（房速）。可将消融灶分为3种类型,其中以7字形的A型线性消融最关键,71．6％的阵发性房颤可被A型消融终止且不再被诱发,而68．8％的持续性／永久性房颤则需通过B型消融终止。随访（21．6±5．3）个月,90．3％（112／124）的患者不服药亦无房颤发生。其余9．7％（12／124）的患者有顽固性非典型房扑／房速,其中仅1．6％（2／124）的患者伴有阵发性房颤。结论 递进式的心房基质消融术可以将房颤有效地转复为窦性心律,并有满意的远期疗效。此种术式简单易行有望在NavX和Carto标测下复制。     

双腔起搏器植入术后对三度房室传导阻滞患者左心房功能的影响

目的：应用应变率成像（SRI）技术评价右室流出道起搏对于三度房室传导阻滞患者左心房功能的影响。方法：分别于双腔起搏器植入术前、术后1个月和术后3个月应用SRI技术对20例三度房室传导阻滞患者左心房功能进行评价。结果：与术前比较,术后1月左心房收缩期前容积[（30．17±2．92）ml比（27．66±3．25）ml]、最大容积[（47．00±2．94）ml比（44．25±3．15）ml]、最小容积[（18．27±3．02）ml比（16．14±2．54）ml]明显减小（P均〈0．05）,心室收缩期左心房峰值应变率（SRS）[（3．82±0．28）S-1比（3．58±0．32）S-1]降低,心室舒张晚期左心房峰值应变率FSRa,（-2．49±0．29）S-1比（-2．72±0．31）S-1]和心室舒张早期左心房峰值应变率[-SRc,（-3．11±0．28）S-1比（-3．32±0．27）S-1]升高,术后3月,上述指标变化更为显著（P〈0．01）;术后3月主动排空分数[（25．78±9．00）％比（49．39±9．33）％]和被动排空分数[（35．77±5．40）％比（41．46±7．44）％]、左室射血分数[（62．85±3．27）％比（65．75±2．87）％]明显升高（P〈0．05～〈0．01）;与术前相比,术后3个月左室射血分数的变化率与SRa的变化率呈显著的正相关（r=0．522,P〈0．05）。结论：双腔起搏器植入术后可影响三度房室传导阻滞患者的左心房的功能,表现为管道和辅泵功能增加,储器功能下降。     

Right atrial modification of maze surgery does not affect refractoriness and conduction patterns of human lone atrial fibrillation.

BACKGROUND: Tissue mass and structure are relevant for initiation and persistence of fibrillation. Modification of the right atrium during maze surgery may change the arrhythmogenic substrate of atrial fibrillation (AF). METHODS AND RESULTS: Epicardial mapping was performed in 9 patients undergoing unmodified maze III surgery for lone paroxysmal AF. Simultaneous recording of AF on the right and left atrium was carried out with two spoon-electrodes each harbouring 64 terminals. Activation maps of AF were made to study AF wavelet organization. The recording position on right and left atria was outside the surgical field and remained unchanged before and after surgery. Before surgery, mean right and left fibrillatory intervals were 174+/-23 ms, and 175+/-26 ms, respectively, and did not differ. After completed right atrial surgery, these fibrillary intervals remained unchanged. Mean right and left atrial dispersion of refractoriness (expressed as the coefficient of variation) were 4.2+/-0.8 and 5.2+/-3.8 ms. Only right atrial dispersion of refractoriness increased significantly after right-sided surgery. Prior to surgery, activation patterns of the left atrium were more complex than that of the right atrium. The left activation patterns became less complex afterwards; the right atrial activation patterns did not change. CONCLUSION: The right atrial modification of maze III surgery neither affects atrial refractoriness during human lone AF nor changes AF wavelet organization. Thus, right atrial surgery does not modify the arrhythmogenic substrate of AF. These findings may imply that maze surgery can be restricted to the left atrium.     

快速右心房起搏致犬心房迷走神经重构的研究

目的 通过对快速心房起搏犬的神经相关因子的研究,观察右心房快速起搏48 h是否引起神经重构及其在心房颤动(房颤)中的作用.方法 健康杂种犬12只,随机分为房颤组(6只)和对照组(6只).右心房起搏600次/min、持续48 h.通过一种在发芽轴突生长丘中表达的蛋白质(GAP-43)和乙酰胆碱转移酶(CHAT)来了解心脏神经萌发和迷走神经的重构.结果 在房颤犬的左心房、左心耳、右心房和右心耳,GAP-43和CHAT的神经密度同对照组相比明显增高,差异均有统计学意义(P<0.05).此外,房颤犬的右心房GAP-43和CHAT的神经密度与左心房有明显差异(P<0.05),显微镜下显示每个样点心脏神经不均匀分布.结论 48 h持续起搏犬右心房形成阵发性房颤,可见明显的神经萌发和迷走神经重构且不均一分布.     

Regional atrial myocardial velocity in normal fetuses: evaluation by quantitative tissue velocity imaging

Objectives: Quantitative tissue velocity imaging (QTVI) is a new noninvasive method that derives measurements of velocities directly from the myocardium. Data on atrial myocardial tissue velocities in normal fetuses have not been established. The objective of this study was to evaluate atrial myocardial velocity and the myocardial velocity gradient of normal fetuses by using QTVI. Methods: We measured motion velocities of the left and right atrial wall along the long axis in 50 normal fetuses aged 21–32 weeks gestation (mean, 25.3 ± 2.8 weeks). In all fetuses, peak myocardial velocity during early diastole (EW), atrial contraction (AW), and ventricular systole (SW) waves was recorded in the basal and mid‐atrial segments. Correlation analysis was conducted between segmental velocities of the left atrium (LA) and right atrium (RA) and gestational age. Results: The mean values for EW, AW, and SW of the long axis in the same right basal segment of the RA were greater than those of the LA (P < 0.01). There was a degressive gradient with velocity from the basal to superior in the atrial wall. There was a linear relationship with gestation for all basal myocardial velocities of the left and right atrial free wall (P < 0.05). However, the myocardial velocity variables of the midatrial wall showed no age‐dependence. Conclusion: We demonstrated that QTVI is reproducible and provides readily obtained parameters that provide unique data regarding segmental atrial myocardial velocity in normal fetuses. (Echocardiography 2012;29:182‐186)