美國醫(yī)學超聲協(xié)會胎兒超聲心動圖操作指南-中文

1、美國醫(yī)學超聲協(xié)會胎兒超聲心動圖操作指南I 簡介先天性心臟病是導致胎兒死亡的主要原因，死亡率約為 6。準確的產前診斷能夠改善嬰兒的預后，尤其在需要前列腺素來維持動脈導管通暢的病例中更為重要。胎兒超聲心動圖普遍認為是產前評價胎兒心臟畸形的最詳 細的檢查手段。其檢查手段是在“基本”和“基本擴展”胎兒成像指南基礎上延伸而出的，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間的情況下進行。有時，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重的先心病。II人員

2、的資質及責任參照AIUM官方文件醫(yī)師培訓指南、診斷超聲檢查評估與解釋、AIUM超聲實踐標準指南III指征胎兒超聲心動圖指征基于先心病的親代及胎兒危險因素。然而，大多數病例并沒有明確的已知的高位因素。胎兒超聲心動圖的普通指征是（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?。ㄈ纾禾悄虿『捅奖虬Y）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透明層增厚單絨毛膜雙胎無法解釋的羊水過多IV檢查申請書面或電子申請超聲心動圖檢查應提供詳細的信息以更好的完成檢查。檢

3、查申請必須由臨床醫(yī)生或其他有資格的健康中心出具，并提供相關臨床資料，并且因遵守相關法律和當地健康結構規(guī)定。V 檢查說明以下部分為胎兒超聲心動圖詳細或選擇性推薦。A綜述胎 兒超聲心動圖通常在孕18到22周進行。有些先心病可能在更早孕周發(fā)現。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。檢查者可以通過調節(jié)各種參數來獲得最好的圖像，比如焦點、 頻率、增益、圖像放大、時間分辨率、諧波成像及多普勒相關參數（比如：血流速度、壁濾波、幀頻）。B心臟圖像參數：基本要求：胎兒超聲心動圖是對心臟

4、結構及功能的全面評價。檢查方法包括三個節(jié)段的分析：心房、心室、大動脈及其連接。節(jié)段分析法包括以下連接及關系：心房位置房室連接心室與動脈流出到的連接每個節(jié)段的異常都需要對其他伴隨異常進行評價比如：心臟位置、心房異構、主動脈騎跨、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、卵圓孔關閉、心室比例失調、動脈縮窄及二三尖瓣發(fā)育異常。C灰階圖像（推薦）關鍵切面的獲取有助于診斷信息的獲得。應該獲得以下切面：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）主動脈弓導管弓上腔靜脈下腔靜脈D 多普勒檢查（心臟血流異常時推薦）使用光譜、連續(xù)、彩色和或能量多普勒來評價下列結構的血流或

5、心律異常：肺靜脈卵圓孔房室瓣房室間隔主、肺動脈瓣動脈導管主動脈弓EM型超聲心動圖（心率或心律異常時推薦）M 型超聲心動圖顯示一個薄的取樣容積內結構隨時間的變化。較高的時間分辨率有助于心室收縮的評價。能夠分辨房性、室性心律失常，及它們之間的關系。其他方法如：脈沖多普勒或者組織多普勒也被用來評價胎兒心律失常。F.心臟生物學測量（在結構異常時推薦）胎兒心臟測量的正常范圍根據不同孕周或胎兒大小而不同，數據已經以百分位數和z積分的形式公布。每個個體的測量應使用M型或二維圖像，包括以下參數：主動脈及肺動脈瓣環(huán)水平內徑主動脈弓及峽部內徑舒末期心室內徑，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

6、量按需要而定，包括：心室收縮內徑心房的橫徑肺動脈分支內徑G.補充切面（可選）其他附屬成像模式，比如3或4維超聲，已經應用于心臟結構異常和定量胎兒血流參數（比如心輸出量）的應用。多普勒超聲和斑點追蹤技術被用來描述心室的應變和心肌指數的測量。VI報告及存檔充足的存檔對高質量病例管理是必要的。胎兒超聲 心動圖檢查和說明應該永久存儲。所用的圖像包括正常和異常的都應該存檔。異常時應該同時附有測量數據。圖形應標注病人信息、儀器信息、檢查日期、以及圖像 左右方向。正式報告（最終報告）應收錄在病人的醫(yī)療檔案中。超聲的檢查應有臨床適應癥，并且遵守相關法律及當地健康結構的規(guī)定。報告應符合AIUM超聲檢 查標準。V

7、II儀器要求胎兒超聲心動圖檢查應該使用實時探頭掃查。因此 應使用扇形、凸陣及經陰道探頭。盡量將探頭頻率調至最佳，值得注意分辨率與掃查深度是相互制約的。對目前設備而言，經腹壁探查時經常使用頻率為 3.5MHz或更高，而經陰道掃查時頻率為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質量控制及提高、安全性、感染控制、患者教育質量控制及提高、安全性、感染控制的執(zhí)行應符合AIUM超聲實踐標準及指南。儀器的工作輻射監(jiān)控應符合AIUM超聲實踐標準及指南。IX.ALARA 原則每次檢查的益處及風險應同時評估。在控制聲能輸出及掃查時間時應遵守ALA

8、RA原則（低聲能、短時間）。更詳細內容見AIUM發(fā)布的醫(yī)學超聲安全。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.美國超聲醫(yī)學協(xié)會（AIUM）和國際婦產科超聲協(xié)會最近針對胎兒心臟超聲檢查出臺了一項指南。國際婦產科超聲協(xié)會指南包括了基于四腔心切面的最基本的心臟檢查，其中重點強調了在此超聲切面上的幾個關鍵征象，同時指南還包括了“進一步”的檢查，包括對左右心室流出道（RVOT和LVOT）的檢查，明確兩者的關

11、系對于發(fā)現圓錐動脈干畸形非常重要。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).由于一些技術上的原因，比如母體的體質、胎齡或者胎兒體位等因素的影響，有時顯示ROVT和LOVT的關系比較的困難。除了可以通過常規(guī)二維圖像來顯示流出道外，還可以應用三維影像技術包括使用多維動態(tài)圖像技術來顯示流出道。即便是具備了先進的影像技術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，否則仍有可能無法發(fā)現先天性心臟病。因此，即便是有了很多先進的影像技術，但如果要發(fā)現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的心臟影像技術的跳板。除了這些切面之外，我們還需要對胎兒心臟進行

16、其他的廣泛細致的檢查，我們可以通過4到5個短軸切面來獲取，包括胃泡、四腔心切面、五腔心切面、肺動脈分叉以及三血管排列（肺動脈、主動脈和上腔靜脈）。 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).在胎兒心臟的基礎的檢查中我們可以通過PASSSS這個詞來進行記憶，每個字母可作為一個檢查的要點：位置、軸向、大小、對稱軸、間隔和節(jié)律。如果檢查者能夠發(fā)現心臟的每一個征象并認為正常，那么他可以認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?。捍_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. 胎兒心臟檢查時首先我們要明確胎兒的胎位，然后必須要確定胎兒的左側是在上還是在下，最后要明確胃泡在哪邊以及胃泡和心臟的位置關系。簡單的說，心房正位是正常的關系，胃泡和左心房位于胎兒的左側。心房反位是心房正位的鏡像面，胃泡位于

22、左側但左心房位于右側。心臟不定位是一種解剖學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看一下四腔心切面（表2）。我們可以通過辨認胎兒胸椎然后對胸腔進行橫切面掃面獲得四腔心切面。從解剖學上來說，右心室位于胸骨的后方，左心室在右心室的左側或者和胃泡同在一側。右心室獨有的征象包括與胸骨的關系、三尖瓣的附著點比二尖瓣低以及粗大的調節(jié)束。卵圓孔瓣從右心房向左心房開放。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卵圓瓣 - 出現在左房內房室瓣在室間隔上的附著點 三尖瓣的附著點低于二尖瓣 二尖瓣的附著點高于三尖瓣肌層 可見調節(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一條線，室間隔與之成40-45°的角。Shipping等人發(fā)現正常心軸為43°，SD為7°（圖1）。心軸異?？赡鼙砻鞔嬖谛耐獾男厍粌犬惓D壓心臟，比如肺臟的囊性腺瘤樣畸形、膈疝或者胸腔隔離肺。心軸的偏轉也可以是由于心內的異常導致，比如Ebstein畸形和Fallot四聯征。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，心臟大約占整個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系，心臟的面積大約是胸腔面積的三分之一（圖1）。簡單的說，正常情況下一個胸腔大約能放置三個心臟。心臟過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，心內的異常有Ebstein畸形、心肌病變或者心臟腫瘤（最常見的是橫紋肌瘤）。 Symmetry 對稱性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.對稱性是指心室大小對稱，通常情況下，左右心室的直徑保持大約1:1的比例（圖2）。當右室直徑比左室略大的話，實時檢查可以大體的估測心室的腔徑。最常見的異常是心臟左側或右側的發(fā)育不良，左心發(fā)育不全綜合癥包括有主動脈、主動脈瓣膜、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種異常導致：肺動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導致腔徑的不對稱。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出現的衰減偽像。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，可發(fā)生在主動脈瓣下的膜周部。彩色多普勒有助于明確診斷。房間隔缺損非常難以發(fā)現，因為存在正常的卵圓孔。房室通道是由于心內膜墊缺損導致的，發(fā)生這種情況時我們看不到正常情況下的三尖瓣附著點低于二尖瓣，而是殘存的二尖瓣和三尖瓣附著點在同一水平呈T型結構，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。示意圖顯示三尖瓣距離心尖要比二尖瓣近。當出現房室通道時，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。妊娠的早期心率會快速增高，8周的時候可以達到175bpm（SD，20bp

48、m），到20周的時候逐漸的降到140bpm（SD，20bpm），足妊時為135bpm（SD，20bpm）。胎兒心律異常包括（1）心律不規(guī)整，（2）異常過緩或過速，或者（3）兩者都存在。M型超聲對于發(fā)現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監(jiān)測心房和心室壁在收縮期的室壁運動的順序。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經過心房和心室壁，這樣的話心房和心室的M波形才能同時顯示出來從而能觀察到心房的收縮和向心室的傳導。簡單的說，胎兒心律失常最常見的病因包括房性期前收縮和短暫的竇性心動過速和心動過緩，少見的情況還包括房室阻滯和室上性心動過速。胎兒心律失常至少出現在

49、2%的妊娠中，也是常見的進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. 我們還可以通過觀察流出道的長軸切面來提高CHD的檢出率，在這個切面上，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45度使得探頭從胎兒上腹部指向右肩就可以獲得左室長軸切面（圖4）。在此切面上可以顯示起源于左心室的主動脈。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.通過這個切面有助于顯示室間隔的膜部。當我們看到主動脈流出道時將探頭輕輕一動就可以顯示出與右心室相連的主肺動脈。主肺動脈和升主動脈相互垂直或者說呈“十字交叉”就可以排除動脈圓錐的異常，比如大動脈轉位。當顯示出流出道的長軸切面時我們需要確定血管的十字交叉情況（圖4）。如果有困難，那么我們可以根據血管的解剖特性來確定。主

55、動脈與左心室相連然后延伸為主動脈弓，其分支走向頭頸部。同時，主肺動脈起源于右心室，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，從四腔心切面轉變到傾斜的掃描平面上可以看到左心室與主動脈相互通聯（箭頭）。E，旋轉探頭可以看到起源于右心室的肺動脈（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