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成人型与婴儿型左冠状动脉异常起源于肺动脉的超声诊断

2014-01-24李文秀张桂珍

中国循证儿科杂志 2014年3期
关键词:主干心动图肺动脉

李文秀 耿 斌 吴 江 陈 敏 张桂珍

·论著·

成人型与婴儿型左冠状动脉异常起源于肺动脉的超声诊断

李文秀1耿 斌1吴 江1陈 敏2张桂珍1

目的 总结不同类型左冠状动脉异常起源于肺动脉(ALCAPA)的超声心动图表现,提高对本病的诊断及鉴别诊断能力。方法 回顾性分析首都医科大学附属北京安贞医院儿童心血管病中心收治并经手术证实的24例ALCAPA患儿的超声心动图结果,根据侧支循环的发育情况分为婴儿型和成人型,并总结婴儿型和成人型ALCAPA的超声心动图特征。结果 婴儿型和成人型ALCAPA相同的超声心动图特征:①左冠状动脉窦内无左冠状动脉主干开口,其主干直接与肺动脉连接;②左心室高度扩张,室间隔和左室前壁节段性运动障碍,左室收缩功能减低;③左心室广泛纤维化,以心内膜下区域最为显著;④二尖瓣腱索、乳头肌纤维化,回声显著增强;⑤右冠状动脉起源位置正常,内径增宽;⑥左冠状动脉前降支和回旋支血流为逆向灌注(向心性);⑦收缩期二尖瓣口可见少至大量反流信号。婴儿型和成人型ALCAPA不同的超声心动图表现:彩色多普勒显示成人型侧支循环血流丰富,婴儿型侧支循环少。结论 婴儿型和成人型ALCAPA具有其特异性的超声心动图特征,结合其临床及心电图等表现,可以对本病做出正确诊断。

左冠状动脉异常起源于肺动脉; 超声心动图; 侧支循环

左冠状动脉异常起源于肺动脉(ALCAPA)是一种发病率极低的先天性冠状动脉起源异常,文献报道ALCAPA在婴幼儿中发病率约为1/30万[1],占先天性心脏病的0.25%~0.50%[2],是导致婴幼儿心肌缺血、心肌梗死的常见病因之一[3],手术是根治本病的唯一手段[4,5]。根据冠状动脉间侧支血管发育的情况,ALCAPA分为婴儿型和成人型[6],婴儿型冠状动脉间侧支血管发育差,临床症状严重,未行手术治疗的婴儿型患儿1岁内病死率高达90%[7];成人型侧支血管发育丰富,症状较轻,部分患儿可生存至成年,但若治疗不及时,最终会死于心力衰竭或心源性猝死[7]。中国自20世纪80年代开始逐渐对ALCAPA进行了报道,但例数较少,临床医生及影像学医生对其认识有限,多数病例被误诊或漏诊,耽误了患儿的治疗。目前,先天性心脏病首选的检查方法仍然是超声心动图,因此,临床医生特别是超声医生应该对ALCAPA的超声心动图表现有全面的认识,减少误诊及漏诊。本文通过回顾性总结婴儿型和成人型ALCAPA的超声心动图特征,以期全面认识并提高对本病的诊断及鉴别诊断能力。

1 方法

1.1 诊断标准及分型 ALCAPA是指左冠状动脉主干或其分支(左前降冠状动脉或左回旋冠状动脉)起源于近端肺动脉干或极少数起源于近端右肺动脉[3]。根据冠状动脉间侧支血管发育的情况分为婴儿型和成人型[6]。

1.2 纳入标准 1997年1月至2013年10月首都医科大学附属北京安贞医院儿童心血管病中心住院并经手术证实诊断为ALCAPA的连续病例。

1.3 病历资料截取 截取手术前病史中的以下资料用于本文分析:①一般情况:年龄、性别和生长发育情况(依据不同年龄段、不同性别正常儿童的身高/年龄、体重/年龄标准差数值表[8]评判);②临床资料:临床症状和体征,合并其他心脏畸形,ECG,影像学检查(胸部X线片和超声心动图等),误诊疾病;③预后。

1.4 超声心动图检查 采用HP5000、AcusonSequioa 512、Philips IE33彩色超声诊断仪,选择探头S5-1,频率1~5 MHz;婴幼儿冠状动脉显示不满意时选用探头S12-4,频率4~12 MHz。受检者取平卧位、左侧卧位或右侧卧位;常规超声心动图探查心内结构及瓣膜反流情况,通过室壁运动情况评价左室功能。应用二维超声多切面重点探查左、右冠状动脉的起源部位、走行、内径及肺动脉与左冠状动脉的关系;应用彩色多普勒超声重点观察左、右冠状动脉内血流方向及肺动脉内的异常血流,左、右冠状动脉之间侧支循环情况及肺动脉主干内有无冠状动脉异常的逆灌血流。

2 结果

2.1 一般情况 24例ALCAPA患儿进入本文分析,其中男8例,女16例。婴儿型9例,年龄3个月至4岁6个月,中位年龄8.5个月;成人型15例,年龄1岁2个月至16岁10个月,中位年龄60个月。左冠状动脉起源于肺动脉左后窦11例,起源于肺动脉右后窦6例,其他7例。5例合并卵圆孔未闭,3例合并壁内冠状动脉。24例均行手术治疗,死亡5例,其中婴儿型4例,成人型1例。

2.2 误诊情况 24例ALCAPA患儿中,曾误诊为心内膜弹力纤维增生症7例(婴儿型4例,成人型3例);原发性扩张性心肌病3例(婴儿型2例,成人型1例);右冠状动脉-肺动脉瘘2例(均为成人型);瓣膜病1例(成人型)。

2.3 临床症状和体征 24例均有活动耐量低,活动后心慌、气短,胸闷,平素多汗等症状。所有患儿均无青紫。心尖部均可闻及2~3/6级收缩期杂音。生长发育落后6例(婴儿型和成人型各3例)。1例成人型患儿就诊前1年出现过晕厥症状。

2.4 影像学检查

2.4.1 胸部X线片 肺血增多10例(婴儿型3例,成人型7例),肺纹理增粗3例(婴儿型2例,成人型1例),肺血减少2例(婴儿型和成人型各1例)。

2.4.2 ECG 16例出现左心室前侧壁心肌梗死心电图表现,Ⅰ导联异常Q波12例(婴儿型7例,成人型5例),avL导联异常Q波16例(婴儿型和成人型各8例),V4~V6导联异常Q波15例(婴儿型8例,成人型7例)。24例均有ST-T波压低。

2.4.3 超声心动图 术前超声心动图测量结果显示,婴儿型和成人型患儿心功能差异有统计学意义,左、右冠状动脉主干与主动脉环直径比值差异无统计学意义(表1)。

婴儿型和成人型ALCAPA患儿相同的超声心动图表现:①主动脉左冠状动脉窦内无左冠状动脉主干开口,左冠状动脉主干直接与肺动脉连接(图1A),彩色多普勒可清晰显示异常起源的左冠状动脉主干开口(图1B);②左心室高度扩张,以心尖区扩大更为明显,室间隔和左室前壁节段性运动障碍,左室收缩功能减低(图1C);③左心室广泛纤维化,以心内膜下区域最为显著,严重者可出现一定范围的心肌梗死病灶,4例(婴儿型3例,成人型1例)合并心尖部室壁瘤形成(局部室壁扩张、变薄,病变区薄层的心室壁向外膨出,心脏收缩时丧失活动能力或呈现反常运动);④二尖瓣腱索、乳头肌纤维化,回声显著增强,可伴有二尖瓣脱垂(图1D);⑤右冠状动脉起源位置正常,内径增宽;⑥左冠状动脉前降支和回旋支血流为逆向灌注(向心性)(图1E);⑦收缩期二尖瓣口可见少至大量反流信号(图1F)。

婴儿型与成人型ALCAPA患儿不同的超声心动图表现:成人型侧支循环丰富,彩色多普勒显示左、右冠状动脉之间侧支循环血流丰富(图1G);婴儿型侧支循环差,彩色多普勒显示左、右冠状动脉之间稀疏的侧支循环,彩色血流暗淡(图1H)。

图1 婴儿型和成人型ALCAPA超声心动图表现

Fig 1 The features of echocardiography of different types of ALCAPA

Notes A: There was no ostium of main LCA in the left coronary sinus of aorta on the left side high parasternal section.The anterior descending and left circumflex of LCA were shown clearly on two-dimensional ultrasound; B: Color Doppler showed the inverse red color flow from LCA to PA; C: The LV was enlarged; D: The ultrasonography of ALCAPA, the chamber of LV and LA were enlarged and the echo of mitral valve tendon was enhanced (arrow) on parasternal left ventricular long axis section; E: Color Doppler showed the inverse color flow in LAD and LCx at the diastole phase; F: Color Doppler showed moderate mitral valve regurgitation; G: The significant collateral vessels were established between the RCA and LCA (arrow)on apex four chamber view; H: The ultrasonography of infantile types of ALCAPA, the small and thin collateral vessels (arrow)were established between the RCA and LCA on left ventricular short axis view. LCA: left coronary artery; PA: pulmonary artery; AO: aortic; RCA: right coronary artery; LAD: anterior descending of left coronary artery; LCx: left circumflex of left coronary artery; LV: left ventricle; RV: right ventricle; LA: left atrium; RA: right atrium

3 讨论

ALCAPA是一种罕见的冠状动脉起源异常,虽然文献报道其发病率非常低,但在临床工作中发现部分ALCAPA患儿常被漏诊及误诊,因此ALCAPA的发病率可能被低估。究其原因是临床医生和超声医生对ALCAPA认识有限,特别是超声医生对ALCAPA的超声心动图表现未完全掌握,同时由于婴儿型和成人型的ALCAPA超声心动图表现存在不同之处,而且ALCAPA在不同时期的病理生理学改变不同,因此更易造成临床漏诊或误诊。

婴儿型发病率较高,冠状动脉间侧支血管发育差,症状严重,心肌收缩无力,常于早期因心力衰竭而夭折,部分患儿婴儿期出现心力衰竭症状后,经内科保守治疗后症状好转,而在治疗阶段,冠状动脉侧支血管逐渐形成增多,这部分患儿仍归为婴儿型。成人型发病率较低,侧支血管丰富,症状较轻,在婴儿期无症状,仅劳累后出现心绞痛等症状,往往在偶然检查中发现心脏增大或以心脏杂音就诊[9]。本文婴儿型病例较少(9/24),考虑婴儿型患儿发病较早,症状较重,部分患儿未经明确诊断及治疗即夭折。此外,本文未纳入我院门诊确诊,但左室收缩功能低,暂时不能进行外科治疗的婴儿型病例。

不同时期ALCAPA病理生理学改变不同[6,10]。新生儿期,由于肺循环压力和阻力均较高,肺动脉内的低氧血流可经异常起源的左冠状动脉正向灌注左室心肌,虽然此时左室心肌血氧饱和度降低,但血流量仍能保持正常灌注,血流方向为右冠状动脉→侧支循环→左冠状动脉,再加上新生儿未成熟的心肌耐受缺氧能力高于耐低压能力,因此,新生儿期ALCAPA患儿可不出现明显的心肌缺血症状,可仅表现为多汗症状。出生后3个月,随着新生儿肺动脉压力的逐渐下降,左冠状动脉灌注压严重不足,常出现逆向灌注,即右冠状动脉血流通过冠状动脉间的侧支循环逆向灌注到左冠状动脉后,再经左冠状动脉的异常开口将血流逆向灌注到压力更低的肺动脉内,此时血流方向为右冠状动脉→侧支循环→左冠状动脉→肺动脉,此时心肌会出现缺血症状,若患儿侧支血管发育差或侧支发育不及时,症状会非常严重,可表现为平素气促、易呛奶、多汗和生长发育迟缓等症状,即婴儿型ALCAPA。当患儿冠状动脉间及时建立侧支循环,并且侧支血管丰富时,大量血流通过丰富的侧支灌注到左室的前壁和侧壁,心肌缺血症状可得到一定程度的缓解,多数患儿出现症状较晚,可有胸闷、活动后气促、劳累后心绞痛和慢性充血性心力衰竭等症状,部分患儿症状不明显,多在成年后偶然检查发现,即成人型ALCAPA。

婴儿型和成人型ALCAPA患儿具有相同的超声心动图及ECG表现,这与其病理及病理生理改变密切相关。本病根本的病因为左冠状动脉主干与肺动脉异常连接,其最常见的异常起源部位是肺动脉左后窦,其次为右后窦;由于心肌缺血,可导致心内膜的供血不足而产生心内膜弹性纤维组织增生、纤维化、乳头肌功能失调、二尖瓣键索的融合和缩短,超声心动图表现为左心室高度扩张、心内膜及二尖瓣腱索回声明显增强,此外,纤维化还可导致心脏增大呈球形扩大及二尖瓣环扩大,最终导致不同程度的左室收缩功能减低及二尖瓣关闭不全,听诊时心前区即出现收缩期二尖瓣反流产生的杂音,ECG出现左心室前侧壁心肌梗死表现,即Ⅰ、avL、V4~V6导联深宽Q波;部分患儿出现心肌缺血表现,即ST-T波压低;部分患儿还可形成室壁瘤,本文4例患儿合并心尖部室壁瘤形成。由于右冠状动脉是唯一供应心肌血液的动脉,因此右冠状动脉代偿性的内径增宽,而冠状动脉前降支和回旋支血流为逆向灌注(向心性)。

婴儿型ALCAPA超声心动图及临床表现与心内膜弹力纤维增生症(EFE)和先天性左冠状动脉主干闭锁(LMCAA)相似[11],因此常被误诊为EFE和LMCAA;成人型ALCAPA超声心动图及临床表现与原发性扩张性心肌病(DCM)、瓣膜疾病和冠状动脉瘘等相似[12~14]。本文13例患儿曾被误诊,究其原因是对ALCAPA认识不足,因此,超声医生对怀疑EFE、DCM、瓣膜疾病和冠状动脉瘘患儿的检查过程中,要多切面、多角度对冠状动脉进行重点检查,减少漏诊及误诊。

在ALCAPA的超声心动图表现中,二尖瓣腱索、乳头肌回声增强是具有指导意义的超声表现,有研究者认为乳头肌回声增强是鉴别ALCAPA和DCM的重要指标[7,15],本文的临床体会也认为这一超声表现对诊断ALCAPA有重要的意义,当超声心动图检查发现二尖瓣腱索、乳头肌回声增强时应重点观察冠状动脉的情况,如果还同时具有ECG的相关表现,则对超声医生诊断ALCAPA有进一步的提示作用,最终可准确诊断。

本文不同类型ALCAPA患儿术前超声心动图检查结果显示,成人型术前心功能正常,婴儿型术前心功能明显减低,差异有统计学意义,而左、右冠状动脉主干与主动脉环直径比值差异均无统计学意义。但本文婴儿型仅9例,因此各项超声心动图参数有待于增加病例后进一步研究。

ALCAPA最终的治疗方式是重建两个冠状动脉系统的外科手术。目前的理论认为无论是婴儿型或成人型的ALCAPA,即使患儿没有症状也应尽早手术,才能解决肺动脉从左冠状动脉窃血的问题,从而进一步避免心肌的缺血损伤,预防乳头肌功能失调的发生,并最终改善左心功能和预防心力衰竭或猝死的发生,但临床工作中常会遇到各种情况导致手术治疗的延误。

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(本文编辑:张萍)

The echocardiography diagnosis of infantile and adult types of anomalous origin of the left coronary artery from the pulmonary artery

LI Wen-xiu1, GENG Bin1, WU Jiang1, CHEN Min2, ZHANG Gui-zheng1

(1 Pediatric Cardiovascular Center,Beijing Anzhen Hospital affiliated to the Capital Medical University, Beijing 100029, China; 2 Department of Ultrasound, PLA 302 Hospital, Beijing 100089, China)

GENG Bin,E-mail:geng_bin1@163.com

ObjectiveTo improve the diagnosis and differential diagnosis ability for different type of anomalous origin of the left coronary artery from the pulmonary artery(ALCAPA) by summarizing patient's echocardiography features and in combination with its clinical and electrocardiogram performances. MethodsThe echocardiography results of twenty-four cases with confirmed diagnosis of ALCAPA by surgery were retrospectively reviewed. According to the development of coronary artery collateral circulation, patients were divided into infantile type and adult type. The different and the common echocardiography features were summarized in two types of ALCAPA. ResultsThe same echocardiography features of infantile and adult types: ①There was no left main coronary artery ostium in left coronary cusp, in stead, the left coronary artery(LCA) was originated from pulmonary artery. ②Left ventricle chamber was enlarged obviously. The segments movement of interventricular septum and anterior wall of left ventricle was disorderd. The systolic function of left ventricle was reduced. ③The fibrosis of left ventricle was extensive and the area of endocardium was significant. ④The echo of mitral chordae tendineae and papillary muscle was enhanced. ⑤The diameter of right coronary artery (RPA) was significantly dilated. ⑥The flow of left coronary descending and circumflex branch was inversed. ⑦The mitral regurgitation was mild or severe. The following features differed in infantile and adult types. The significant collateral vessels were established between the RCA and LCA in adult type, however it was not the case for infantile type. The collateral vessels were less in infantile type.ConclusionThe different types of ALCAPA have some specific echocardiography features. Combining patient's echocardiography features with clinical and electrocardiogram performances, the accurate diagnosis can be achieved.

Anomalous origin of the left coronary artery from the pulmonary artery; Echocardiography; Collateral circulation

1 首都医科大学附属北京安贞医院儿童心血管病中心 北京,100029;2 中国人民解放军第302医院超声科 北京,100089

耿斌,E-mail:geng_bin1@163.com

10.3969/j.issn.1673-5501.2014.03.006

2014-03-07

2014-05-25)

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