1、美國(guó)醫(yī)學(xué)超聲協(xié)會(huì)胎兒超聲心動(dòng)圖操作指南I 簡(jiǎn)介先天性心臟病是導(dǎo)致胎兒死亡的主要原因，死亡率約為 6。準(zhǔn)確的產(chǎn)前診斷能夠改善嬰兒的預(yù)后，尤其在需要前列腺素來(lái)維持動(dòng)脈導(dǎo)管通暢的病例中更為重要。胎兒超聲心動(dòng)圖普遍認(rèn)為是產(chǎn)前評(píng)價(jià)胎兒心臟畸形的最詳 細(xì)的檢查手段。其檢查手段是在“基本”和“基本擴(kuò)展”胎兒成像指南基礎(chǔ)上延伸而出的，即胎兒心臟四腔心和流出道切面。胎兒超聲心動(dòng)圖只有在有確切的原因的 情況下，并且最大限度的減少由于采集診斷信息而暴露在超聲下的時(shí)間的情況下進(jìn)行。有時(shí)，額外或特殊的檢查手段比如彩色多普勒是必須的。但并不是所有的畸形 都能夠檢出，以下指南將最大限度的探查大部分臨床嚴(yán)重的先心病。II人員

2、的資質(zhì)及責(zé)任參照AIUM官方文件醫(yī)師培訓(xùn)指南、診斷超聲檢查評(píng)估與解釋、AIUM超聲實(shí)踐標(biāo)準(zhǔn)指南III指征胎兒超聲心動(dòng)圖指征基于先心病的親代及胎兒危險(xiǎn)因素。然而，大多數(shù)病例并沒(méi)有明確的已知的高位因素。胎兒超聲心動(dòng)圖的普通指征是（也不局限與此）：母體指征自身免疫抗體，抗Ro（SSA）/抗La（SSB）家族遺傳疾病（如：馬凡綜合癥）先心病家族史試管嬰兒代謝性疾病（如：糖尿病和苯丙酮尿癥）至畸源接觸（如：類視黃醇和鋰）胎兒指征心臟顯像異常心臟心率心律異常胎兒染色體異常心外畸形胎兒水腫頸項(xiàng)透明層增厚單絨毛膜雙胎無(wú)法解釋的羊水過(guò)多IV檢查申請(qǐng)書(shū)面或電子申請(qǐng)超聲心動(dòng)圖檢查應(yīng)提供詳細(xì)的信息以更好的完成檢查。檢

3、查申請(qǐng)必須由臨床醫(yī)生或其他有資格的健康中心出具，并提供相關(guān)臨床資料，并且因遵守相關(guān)法律和當(dāng)?shù)亟】到Y(jié)構(gòu)規(guī)定。V 檢查說(shuō)明以下部分為胎兒超聲心動(dòng)圖詳細(xì)或選擇性推薦。A綜述胎 兒超聲心動(dòng)圖通常在孕18到22周進(jìn)行。有些先心病可能在更早孕周發(fā)現(xiàn)。最佳的圖像是胎兒心尖向前或朝向孕婦腹壁。由于聲影（如：孕婦肥胖或胎兒俯臥體 位）使得全面的檢查十分困難，特別是在晚孕期更是如此。所以由于心臟顯像欠佳多次觀察是必要的。檢查者可以通過(guò)調(diào)節(jié)各種參數(shù)來(lái)獲得最好的圖像，比如焦點(diǎn)、 頻率、增益、圖像放大、時(shí)間分辨率、諧波成像及多普勒相關(guān)參數(shù)（比如：血流速度、壁濾波、幀頻）。B心臟圖像參數(shù)：基本要求：胎兒超聲心動(dòng)圖是對(duì)心臟

4、結(jié)構(gòu)及功能的全面評(píng)價(jià)。檢查方法包括三個(gè)節(jié)段的分析：心房、心室、大動(dòng)脈及其連接。節(jié)段分析法包括以下連接及關(guān)系：心房位置房室連接心室與動(dòng)脈流出到的連接每個(gè)節(jié)段的異常都需要對(duì)其他伴隨異常進(jìn)行評(píng)價(jià)比如：心臟位置、心房異構(gòu)、主動(dòng)脈騎跨、房間隔缺損、室間隔缺損、心肌肥厚、體循環(huán)或肺靜脈的異常連接、卵圓孔關(guān)閉、心室比例失調(diào)、動(dòng)脈縮窄及二三尖瓣發(fā)育異常。C灰階圖像（推薦）關(guān)鍵切面的獲取有助于診斷信息的獲得。應(yīng)該獲得以下切面：四腔心左室流出道右室流出道三血管及氣管切面短軸切面（心室及流出道）主動(dòng)脈弓導(dǎo)管弓上腔靜脈下腔靜脈D 多普勒檢查（心臟血流異常時(shí)推薦）使用光譜、連續(xù)、彩色和或能量多普勒來(lái)評(píng)價(jià)下列結(jié)構(gòu)的血流或

5、心律異常：肺靜脈卵圓孔房室瓣房室間隔主、肺動(dòng)脈瓣動(dòng)脈導(dǎo)管主動(dòng)脈弓EM型超聲心動(dòng)圖（心率或心律異常時(shí)推薦）M 型超聲心動(dòng)圖顯示一個(gè)薄的取樣容積內(nèi)結(jié)構(gòu)隨時(shí)間的變化。較高的時(shí)間分辨率有助于心室收縮的評(píng)價(jià)。能夠分辨房性、室性心律失常，及它們之間的關(guān)系。其他方法如：脈沖多普勒或者組織多普勒也被用來(lái)評(píng)價(jià)胎兒心律失常。F.心臟生物學(xué)測(cè)量（在結(jié)構(gòu)異常時(shí)推薦）胎兒心臟測(cè)量的正常范圍根據(jù)不同孕周或胎兒大小而不同，數(shù)據(jù)已經(jīng)以百分位數(shù)和z積分的形式公布。每個(gè)個(gè)體的測(cè)量應(yīng)使用M型或二維圖像，包括以下參數(shù)：主動(dòng)脈及肺動(dòng)脈瓣環(huán)水平內(nèi)徑主動(dòng)脈弓及峽部?jī)?nèi)徑舒末期心室內(nèi)徑，緊貼房室瓣下心室自由壁及室間隔的厚度，緊貼房室瓣下額外測(cè)

6、量按需要而定，包括：心室收縮內(nèi)徑心房的橫徑肺動(dòng)脈分支內(nèi)徑G.補(bǔ)充切面（可選）其他附屬成像模式，比如3或4維超聲，已經(jīng)應(yīng)用于心臟結(jié)構(gòu)異常和定量胎兒血流參數(shù)（比如心輸出量）的應(yīng)用。多普勒超聲和斑點(diǎn)追蹤技術(shù)被用來(lái)描述心室的應(yīng)變和心肌指數(shù)的測(cè)量。VI報(bào)告及存檔充足的存檔對(duì)高質(zhì)量病例管理是必要的。胎兒超聲 心動(dòng)圖檢查和說(shuō)明應(yīng)該永久存儲(chǔ)。所用的圖像包括正常和異常的都應(yīng)該存檔。異常時(shí)應(yīng)該同時(shí)附有測(cè)量數(shù)據(jù)。圖形應(yīng)標(biāo)注病人信息、儀器信息、檢查日期、以及圖像 左右方向。正式報(bào)告（最終報(bào)告）應(yīng)收錄在病人的醫(yī)療檔案中。超聲的檢查應(yīng)有臨床適應(yīng)癥，并且遵守相關(guān)法律及當(dāng)?shù)亟】到Y(jié)構(gòu)的規(guī)定。報(bào)告應(yīng)符合AIUM超聲檢 查標(biāo)準(zhǔn)。V

7、II儀器要求胎兒超聲心動(dòng)圖檢查應(yīng)該使用實(shí)時(shí)探頭掃查。因此 應(yīng)使用扇形、凸陣及經(jīng)陰道探頭。盡量將探頭頻率調(diào)至最佳，值得注意分辨率與掃查深度是相互制約的。對(duì)目前設(shè)備而言，經(jīng)腹壁探查時(shí)經(jīng)常使用頻率為 3.5MHz或更高，而經(jīng)陰道掃查時(shí)頻率為5MHz或更高。超聲聲影及母體體型肥胖均可限制高頻探頭的使用，從而限制了心臟高分辨率解剖信息的獲得。VIII質(zhì)量控制及提高、安全性、感染控制、患者教育質(zhì)量控制及提高、安全性、感染控制的執(zhí)行應(yīng)符合AIUM超聲實(shí)踐標(biāo)準(zhǔn)及指南。儀器的工作輻射監(jiān)控應(yīng)符合AIUM超聲實(shí)踐標(biāo)準(zhǔn)及指南。IX.ALARA 原則每次檢查的益處及風(fēng)險(xiǎn)應(yīng)同時(shí)評(píng)估。在控制聲能輸出及掃查時(shí)間時(shí)應(yīng)遵守ALA

8、RA原則（低聲能、短時(shí)間）。更詳細(xì)內(nèi)容見(jiàn)AIUM發(fā)布的醫(yī)學(xué)超聲安全。American Institute of Ultrasound in Medicine (AIUM) and the International Society of Ultrasound in Obstetrics and Gynecology outlined recent guidelines for sonographic evaluation of the fetal heart. The International Society of Ultrasound in Obstetrics and Gynecolog

9、y guidelines include the “basic”cardiac examination that relies on a 4-chamber view.There are key features of this sonographic view that will be emphasized in this article. This society also included the “extended basic” examination that includes the right and left ventricular out-flow tracts (RVOTa

10、nd LVOT, respectively). It is important to include imaging that demonstrates the relationship of the LVOT and the RVOT to detect conotruncal abnormalities.美國(guó)超聲醫(yī)學(xué)協(xié)會(huì)（AIUM）和國(guó)際婦產(chǎn)科超聲協(xié)會(huì)最近針對(duì)胎兒心臟超聲檢查出臺(tái)了一項(xiàng)指南。國(guó)際婦產(chǎn)科超聲協(xié)會(huì)指南包括了基于四腔心切面的最基本的心臟檢查，其中重點(diǎn)強(qiáng)調(diào)了在此超聲切面上的幾個(gè)關(guān)鍵征象，同時(shí)指南還包括了“進(jìn)一步”的檢查，包括對(duì)左右心室流出道（RVOT和LVOT）的檢查，明確兩者的關(guān)

11、系對(duì)于發(fā)現(xiàn)圓錐動(dòng)脈干畸形非常重要。Depending on technical factors, such as maternal body habitus, fetal age, or fetal position, demonstrating the relationship of the RVOT and the LVOT may be problematic. Alternatives to routine 2-dimensional (2-D) imaging of out-flow tracts include the use of 3-D imaging technologies

12、 including the use of dynamic multiplanar imaging. Even with advanced imaging and the ability to reconstruct images in different planes, the examiner must be familiar with routine cardiac views or failure of detection of CHD may still occur. Thus, understanding basic cardiac views is necessary to de

13、tecting CHD even with more advanced imaging. We will concentrate on a method to best understand these basic views, such as the 4-chamber or outflow tract views, as a springboard to more advanced cardiac imaging. An alternative to these views is a comprehensive examination of the fetal heart, which m

14、ay be obtained using 4 to 5 short-axis views of the heart. These 5 planes include (1) the stomach; (2) the 4-chamber view of the heart; (3) the 5-chamber view of the heart; (4) the pulmonary artery (PA) bifurcation; and (5) the alignment of the 3 vessels, which are the PA, aorta, and superior vena c

15、ava (SVC).由于一些技術(shù)上的原因，比如母體的體質(zhì)、胎齡或者胎兒體位等因素的影響，有時(shí)顯示ROVT和LOVT的關(guān)系比較的困難。除了可以通過(guò)常規(guī)二維圖像來(lái)顯示流出道外，還可以應(yīng)用三維影像技術(shù)包括使用多維動(dòng)態(tài)圖像技術(shù)來(lái)顯示流出道。即便是具備了先進(jìn)的影像技術(shù)和不同平面圖像重建的技能，檢查者還必須要掌握常規(guī)的心臟切面，否則仍有可能無(wú)法發(fā)現(xiàn)先天性心臟病。因此，即便是有了很多先進(jìn)的影像技術(shù)，但如果要發(fā)現(xiàn)先天性心臟病仍然需要掌握基本的心臟切面。我們概括了一種最好的方法來(lái)理解這些基本的切面比如四腔心切面和流出道切面，這種方法可以作為其他先進(jìn)的心臟影像技術(shù)的跳板。除了這些切面之外，我們還需要對(duì)胎兒心臟進(jìn)行

16、其他的廣泛細(xì)致的檢查，我們可以通過(guò)4到5個(gè)短軸切面來(lái)獲取，包括胃泡、四腔心切面、五腔心切面、肺動(dòng)脈分叉以及三血管排列（肺動(dòng)脈、主動(dòng)脈和上腔靜脈）。 A useful mnemonic to help In the basic evaluation of the fetal heart is PASSSS. Each letter is meant to serve as a memory aid as follows :position, axis, size, symmetry, septum, and squeeze. If each of these cardiac features i

17、s evaluated and considered normal, the examiner can evaluate the 4-chamber view of the fetal heart PASSSS as normal (Table 1).在胎兒心臟的基礎(chǔ)的檢查中我們可以通過(guò)PASSSS這個(gè)詞來(lái)進(jìn)行記憶，每個(gè)字母可作為一個(gè)檢查的要點(diǎn)：位置、軸向、大小、對(duì)稱軸、間隔和節(jié)律。如果檢查者能夠發(fā)現(xiàn)心臟的每一個(gè)征象并認(rèn)為正常，那么他可以認(rèn)為在胎兒四腔心切面上它是正常的。TABLE 1. The PASSSS Mnemonic for the 4-Chamber Vessel 四腔心切面的PA

18、SSSS記憶法Position Determine correct situs 位置 確定位置是否正常，有無(wú)反位Axis Determine that the interventricular septum is 40 to 45 degrees 軸：確定室間隔的角度在40-45度Size Make sure that the heart is approximately one third of the fetal thorax 大小：確定心臟的大小是胎兒胸腔的三分之一左右Symmetry Generally, the diameters of the right and left vent

19、ricles have a 1:1 ratio 對(duì)稱性：通常情況下，左右心室的直徑為1:1Septum Check the entire septum for possible ductal defects 間隔：檢查整個(gè)間隔明確是否存在可能的缺損Sinus rhythm Check cardiac rate and rhythm 竇性節(jié)律：檢查心律和心率。 In evaluating the fetal heart, the fetal presentation should rst be documented. Then, the examiner must determine if th

20、e fetus left side is up or down. Lastly, the stomach side and its relationship to the heart side should be assessed. Simply put, situs solitus is the normal relationship, with the stomach on the left and the left atrium on the left side of the fetus. Situs inversus is the exact mirror image of situs

21、 solitus, with the stomach on the left but the left atrium on the right. Situs ambiguous is an anatomically indeterminate type of visceral situs, which is part of the heterotaxy syndromes. 胎兒心臟檢查時(shí)首先我們要明確胎兒的胎位，然后必須要確定胎兒的左側(cè)是在上還是在下，最后要明確胃泡在哪邊以及胃泡和心臟的位置關(guān)系。簡(jiǎn)單的說(shuō)，心房正位是正常的關(guān)系，胃泡和左心房位于胎兒的左側(cè)。心房反位是心房正位的鏡像面，胃泡位于

22、左側(cè)但左心房位于右側(cè)。心臟不定位是一種解剖學(xué)上的心房位置不明確的類型，它屬于器官變異綜合癥的一部分。After determining the situs (or position), a 4-chamber view of the heart is obtained (Table 2). This is done by identifying the fetal thoracic spine, and a scan is obtained transverse to the thorax. Anatomically, the right ventricle is posterior to t

23、he sternum, and the left ventricle is to the left of the right ventricle or at the same side as the stomach. Identifying features unique to the right ventricle include its retrosternal location, lower insertion of the tricuspid valve compared with the mitral valve, and a thicker moderator band. The

24、flap of the foramen ovale opens from the right atrium into the left atrium.在明確了心房的位置之后我們可以來(lái)看一下四腔心切面（表2）。我們可以通過(guò)辨認(rèn)胎兒胸椎然后對(duì)胸腔進(jìn)行橫切面掃面獲得四腔心切面。從解剖學(xué)上來(lái)說(shuō)，右心室位于胸骨的后方，左心室在右心室的左側(cè)或者和胃泡同在一側(cè)。右心室獨(dú)有的征象包括與胸骨的關(guān)系、三尖瓣的附著點(diǎn)比二尖瓣低以及粗大的調(diào)節(jié)束。卵圓孔瓣從右心房向左心房開(kāi)放。TABLE 2. Identication of Right and Left Ventricles From the 4-Chamber Vi

25、ewView Right Ventricle Left VentriclePosition within thorax Right ventricle retrosternal Left border, same side as the stomachFlap of foramen ovale Present within the left atriumInsertion of AV valve leaflets on interventricular sternum Tricuspid valve inserted lower than the mitral valve Mitral val

26、ve inserted higher than the tricuspid valveMuscle Thicker moderator bandVeins SVC + IVC Pulmonary veinsIVC indicates inferior vena cava.Modied from DeVore and Polanko.四腔心切面上鑒別左右心室切面 右心室 左心室胸腔內(nèi)的位置 右心室位于胸骨后方 左心室位于左邊和胃泡同處一側(cè)卵圓瓣 - 出現(xiàn)在左房?jī)?nèi)房室瓣在室間隔上的附著點(diǎn) 三尖瓣的附著點(diǎn)低于二尖瓣 二尖瓣的附著點(diǎn)高于三尖瓣肌層 可見(jiàn)調(diào)節(jié)束 -靜脈 上下腔靜脈 肺靜脈 Axis 心軸

27、Once a 4-chamber view of the heart is obtained, a line is drawn from the spine to the anterior sternum. The interventricular septum intersects that line at 40 to 45 degrees. Shipp et al 13 found a normal cardiac axis of 43 degrees, with an SD of 7 degrees (Fig. 1). Abnormal cardiac axis can be an in

28、dicator of extracardiac intrathoracic abnormalities, displacing the heart. Examples include pulmonary cystic adenomatoid malformation, diaphragmatic hernia, or intrathoracic pulmonary sequestration. Axis deviation is also seen in intracardiac abnormalities. Examples include Ebstein anomaly and tetra

29、logy of Fallot.在獲取了四腔心切面后我們可以從脊柱到前面的胸骨畫(huà)一條線，室間隔與之成40-45°的角。Shipping等人發(fā)現(xiàn)正常心軸為43°，SD為7°（圖1）。心軸異常可能表明存在心外的胸腔內(nèi)異常擠壓心臟，比如肺臟的囊性腺瘤樣畸形、膈疝或者胸腔隔離肺。心軸的偏轉(zhuǎn)也可以是由于心內(nèi)的異常導(dǎo)致，比如Ebstein畸形和Fallot四聯(lián)征。FIGURE 1. Four-chamber view of the heart. The 4-chamber view of the heart in the transaxial plane shows the s

30、pine noted posteriorly. A line is drawn from the spine to the anterior sternum. The interventricular septum intersects that line at approximately 45 degrees. Note that the RA lies to the right side of the spinal sternal line. The heart can be noted to occupy approximately one third of the fetal thor

31、ax. RA indicates right atrium.圖1 四腔心切面。在心臟軸向的四腔心切面上我們可以看到脊柱位于后方，從脊柱到前方的胸骨畫(huà)一條線，室間隔與此線大約呈45°。我們可以看到RA位于脊柱胸骨線的右側(cè)，心臟大約占整個(gè)胎兒胸腔的三分之一。 Size 大小This is to assess the size of the fetal heart in relation to the fetal thorax. The cardiac area is approximately one third of the thoracic area (Fig. 1). Simply

32、 put, approximately 3 fetal hearts can normally t into the fetal thorax. A small heart can be attributed to extrinsic mass compressing the heart. There are many causes for fetal cardiomegaly. Intrinsic cardiac anomalies include Ebstein anomaly, cardiomyopathies, or cardiac tumors, most commonly rhab

33、domyomas.胎兒心臟的大小要看和胸腔的關(guān)系，心臟的面積大約是胸腔面積的三分之一（圖1）。簡(jiǎn)單的說(shuō)，正常情況下一個(gè)胸腔大約能放置三個(gè)心臟。心臟過(guò)小可能是由于心外的腫塊擠壓心臟，而心臟增大的原因很多，心內(nèi)的異常有Ebstein畸形、心肌病變或者心臟腫瘤（最常見(jiàn)的是橫紋肌瘤）。 Symmetry 對(duì)稱性This refers to the symmetric size of the ventricles. Generally, the diameters of the right and left ventricles maintain about a 1:1 ratio (Fig. 2).

34、With the diameter of the right ventricle slightly larger than that of the left ventricle, real-time examination can be used as a rough estimate of ventricular chamber size. Most common anomalies are the hypoplasia of either the left or right side of the heart. Hypoplastic left heart syndrome is comp

35、osed of ndings including underdevelopment of the aorta, the aortic valve, the left ventricle, or the mitral valve. Right ventricle hypoplasia can be attributed to 1 of 2 anomalies: pulmonary atresia or tricuspid atresia with or without an intact ventricular septum. There are multiple other etiologie

36、s of chamber discrepancy beyond the scope of this review.對(duì)稱性是指心室大小對(duì)稱，通常情況下，左右心室的直徑保持大約1:1的比例（圖2）。當(dāng)右室直徑比左室略大的話，實(shí)時(shí)檢查可以大體的估測(cè)心室的腔徑。最常見(jiàn)的異常是心臟左側(cè)或右側(cè)的發(fā)育不良，左心發(fā)育不全綜合癥包括有主動(dòng)脈、主動(dòng)脈瓣膜、左心室或二尖瓣的發(fā)育不全。右心發(fā)育不全可能是由于1-2種異常導(dǎo)致：肺動(dòng)脈閉鎖或三尖瓣閉鎖合并或不合并室間隔完整。除此之外，還有很多種其他的原因?qū)е虑粡降牟粚?duì)稱。FIGURE 2. Four-chamber view of the heart. Note that

37、 the diameter of the RV is approximately equal to that of the LV at the AV valve level. RV indicates right ventricle; LV, left ventricle.四腔心切面。在房室瓣水平RV的直徑與LV大約是相等的 Septum 間隔Evaluation for a septal defect is best performed on the 4-chamber heart view that is obtained perpendicular to the interventric

38、ular septum. This allows adequate visualization of the membranous portion of this septum, which can suffer from drop-out artifact if imaging is performed parallel to the interventricular septum. There are 3 basic types of septal defects. Ventricular septal defects (VSDs) can be small or large. The s

39、maller ones are hard to detect and can occur in perimembranous location just below the aortic valve. Color Doppler may be helpful with this diagnosis. Atrial septal defects can be quite difcult to detect because of the normal foramen ovale. The atrioventricular (AV) canal defects result from the abs

40、ence of the endocardial cushion. In this situation, the normal lower insertion of the tricuspid valve compared with the mitral valve is not observed, but rather there is a “T” conguration with the residual mitral and tricuspid valve inserting at the same level but with no interventricular septum (Fi

41、g.3). Color ow imaging allows easier recognition of ventricular defects.檢查室間隔時(shí)最好選取與室間隔垂直的四腔心切面，這樣能非常清楚的看到室間隔的膜部，可以避免因聲束與室間隔平行時(shí)出現(xiàn)的衰減偽像。間隔缺損有三種基本類型。室間隔缺損大小不一，較小的缺損難以發(fā)現(xiàn)，可發(fā)生在主動(dòng)脈瓣下的膜周部。彩色多普勒有助于明確診斷。房間隔缺損非常難以發(fā)現(xiàn)，因?yàn)榇嬖谡５穆褕A孔。房室通道是由于心內(nèi)膜墊缺損導(dǎo)致的，發(fā)生這種情況時(shí)我們看不到正常情況下的三尖瓣附著點(diǎn)低于二尖瓣，而是殘存的二尖瓣和三尖瓣附著點(diǎn)在同一水平呈T型結(jié)構(gòu)，但不與室間隔相連接（圖

42、3）。彩色血流圖像可以很容易的看到室間隔的缺損。FIGURE 3. Valve insertion. This diagram illustrates that the tricuspid valve lies closer to the apex than does the mitral valve. In an AV canal, these valves form a T, along with lack of the interventricular septum.瓣膜附著點(diǎn)。示意圖顯示三尖瓣距離心尖要比二尖瓣近。當(dāng)出現(xiàn)房室通道時(shí)，瓣膜與缺損的室間隔呈T型。 Squeeze 節(jié)律Thi

43、s refers to assessing the normal fetal cardiac rhythm. The normal fetal cardiac rhythm is regular, with a 1:1 atrial-ventricular relationship. The heart rate increases rapidly in early gestation until it reaches the peak rate of 175 beats/min (SD, 20 beats/min) at approximately 8 weeks. Then, the he

44、art rate gradually decreases to 140 beats/min (SD, 20 beats/min) at 20 weeks and 130 beats/min (SD, 20 beats/min) toward term. Fetal rhythm abnormalities include (1) irregularity of the cardiac rhythm, (2) abnormally slow or fast heart rate, or (3) combination of the two. M-mode ultrasound is most c

45、ommonly used to document fetal cardiac rate and rhythm. M-mode line placement becomes important to simultaneously assess the atrial and ventricular walls to record the sequence of their systolic wall motions. The M-mode beam direction is placed through the atrial and ventricular walls immediately ab

46、ove and below the AV junction. At this location, the M-modes of the atrium and the ventricle are displayed together, allowing assessment of atrial contraction and conduction to the ventricles. In brief, most common causes of fetal arrhythmias include premature atrial contractions and brief sinus tac

47、hycardia/bradycardia. Less common arrhythmias include complete AV block and supraventricular tachycardia. Fetal rhythm abnormalities affect at least 2% of pregnancies and are a common reason for referral to fetal cardiologists.這里指的是檢查胎兒心律是否正常。正常的胎兒心律是規(guī)整的，房室比例為1:1。妊娠的早期心率會(huì)快速增高，8周的時(shí)候可以達(dá)到175bpm（SD，20bp

48、m），到20周的時(shí)候逐漸的降到140bpm（SD，20bpm），足妊時(shí)為135bpm（SD，20bpm）。胎兒心律異常包括（1）心律不規(guī)整，（2）異常過(guò)緩或過(guò)速，或者（3）兩者都存在。M型超聲對(duì)于發(fā)現(xiàn)胎兒心律和心率異常非常有用，要注意M取樣線放置的位置保證能同時(shí)監(jiān)測(cè)心房和心室壁在收縮期的室壁運(yùn)動(dòng)的順序。M型超聲的取樣線要在緊鄰房室交界處的上方和下方并同時(shí)經(jīng)過(guò)心房和心室壁，這樣的話心房和心室的M波形才能同時(shí)顯示出來(lái)從而能觀察到心房的收縮和向心室的傳導(dǎo)。簡(jiǎn)單的說(shuō)，胎兒心律失常最常見(jiàn)的病因包括房性期前收縮和短暫的竇性心動(dòng)過(guò)速和心動(dòng)過(guò)緩，少見(jiàn)的情況還包括房室阻滯和室上性心動(dòng)過(guò)速。胎兒心律失常至少出現(xiàn)在

49、2%的妊娠中，也是常見(jiàn)的進(jìn)行胎兒心臟檢查的原因。The PASSSS mnemonic is helpful as a basic evaluation of the 4-chamber heart view.PASSSS記憶法對(duì)于四腔心切面的基本檢查有幫助。 OUTFLOW VIEWS 流出道切面To improve sensitivity of CHD, long-axis views of the outow tracts are obtained, with the interventricular septum perpendicular to the transducer beam

50、. The left ventricular long-axis view of the fetal heart is obtained by rotating the transducer approximately 45 degrees from the 4-chamber view to angle from the fetal abdominal left upper quadrant toward the right shoulder (Fig. 4). This view will demonstrate the aorta originating from the left ve

51、ntricle. 我們還可以通過(guò)觀察流出道的長(zhǎng)軸切面來(lái)提高CHD的檢出率，在這個(gè)切面上，室間隔與探頭的聲束方向是垂直的。在四腔心切面上將探頭旋轉(zhuǎn)45度使得探頭從胎兒上腹部指向右肩就可以獲得左室長(zhǎng)軸切面（圖4）。在此切面上可以顯示起源于左心室的主動(dòng)脈。This view is also useful in the visualization of the membranous portion of the interventricular septum. Once the aortic outow tract is identied, the transducer is “rocked” sli

52、ghtly. This view should demonstrate the main PA exiting the right ventricle. The main PA and the ascending aorta should be perpendicular to each other, or demonstrated to “crisscross”, to exclude conotruncal anomalies such as transposition of the great arteries. When demonstrating the longaxis views

53、 of the outow tracts, it is necessary to conrm crisscrossing of the vessels (Fig. 4). If this proves difcult, dening the anatomic features of the vessels is important. The aorta should be traced originating from the left ventricle to the proximal arch, with demonstration of the takeoffs of the great

54、 vessels to the head and neck. Similarly, the main PA should be demonstrated to arise from the right ventricle; it must be noted to bifurcate.通過(guò)這個(gè)切面有助于顯示室間隔的膜部。當(dāng)我們看到主動(dòng)脈流出道時(shí)將探頭輕輕一動(dòng)就可以顯示出與右心室相連的主肺動(dòng)脈。主肺動(dòng)脈和升主動(dòng)脈相互垂直或者說(shuō)呈“十字交叉”就可以排除動(dòng)脈圓錐的異常，比如大動(dòng)脈轉(zhuǎn)位。當(dāng)顯示出流出道的長(zhǎng)軸切面時(shí)我們需要確定血管的十字交叉情況（圖4）。如果有困難，那么我們可以根據(jù)血管的解剖特性來(lái)確定。主

55、動(dòng)脈與左心室相連然后延伸為主動(dòng)脈弓，其分支走向頭頸部。同時(shí)，主肺動(dòng)脈起源于右心室，并且一定可以看到分叉。FIGURE 4. A-E, Outow tracts apex perpendicular to the ultrasound beam. A, Interventricular septum perpendicular to the ultrasound beam. B, Normal 4 chambers of the heart, with the interventricular septum perpendicular to the ultrasound beam. C, Aft

56、er performing a 4-chamber view of the heart, the transducer is placed at an angle between the left upper quadrant of the abdomen and the right shoulder. D, By changing from the 4-chamber view of the heart to a more oblique scan plane, the aorta is noted exiting the LV, which was noted exiting to the

57、 aorta (arrow). E, The transducer is rotated as the PA is seen to exit from the RV (arrow) and cross-perpendicular to the LVOT.圖4. A-E，流出道與聲束垂直。A，室間隔與聲束垂直。B，正常的四腔心切面，室間隔與聲束垂直。C，在四腔心切面檢查之后將探頭由左上腹指向右肩部。D，從四腔心切面轉(zhuǎn)變到傾斜的掃描平面上可以看到左心室與主動(dòng)脈相互通聯(lián)（箭頭）。E，旋轉(zhuǎn)探頭可以看到起源于右心室的肺動(dòng)脈（箭頭）與左室流出道呈是十字交叉。 When the apex of the he

58、art is “up” or pointed parallel to the ultrasound beam, then it may be more difcult to identify the outow tracts to crisscross. In this situation, the LVOT is again obtained, but often short-axis view must be obtained to identify the RVOT. In this view, the aorta lies centrally, and the right ventricle and PA "wrap around" the aorta. It is important in this view to identify that the vessel originating from the right ventricle is the PA by noting that it bifurcates (Fig. 5).如果心尖上翹或者是與聲束平行的話就更難以確定流出道是否相互交叉排列，在這種情況下可以看到左室流出道，但常常是在短軸切面上才能看到右室流出道。在此切面上，主