多普勒超声测定二尖瓣口阻力

应用多普勒超声心动图测定３２例二尖瓣狭窄患者球囊扩张术前后的二尖瓣口阻力，并与心导管所获左房平均压，肺毛楔压进行相关分析，以探讨二尖瓣口阻力评价血流动力学变化和瓣膜功能损害的临床价值。结果显示：二尖瓣球囊扩张术后，瓣口面积明显增大，瓣口阻力明显降低（Ｐ＜０．０５）；二尖瓣口阻力与左房平均压、肺毛楔压的相关系数分别为０．９０、０．８６、（Ｐ＜０．００１）。表明二尖瓣口阻力可作为二尖瓣狭窄血流动力学和瓣膜功能损害的指标，值得进一步探讨。     

重症心瓣膜病瓣膜置换术后血流动力学状态的临床研究

目的：探讨置换不同口径（#25、#27、#29）的二尖瓣人工机械瓣术后血流动力学状态及对预后的影响。方法：对46例重症心瓣膜病单纯二尖瓣置换术的病人根据术中置换瓣膜口径分为3组，置换#25机械瓣组、置换#27机械瓣组、置换#29机械瓣组，进行血流动力学状态的临床研究，对各组患者随访，采用三维超声心动图、彩色多普勒技术．以正常人作为对照．测量二尖瓣口血流动力学参数，比较各组间的差别。结果：人工机械瓣组（#25、#27、#29）3组二尖瓣口血流动力学的各种参数与正常值比较差异具有显著性意义（P〈0．05），而人工机械瓣各组间比较血流动力学无明显差异。结论：人工机械瓣均有轻度梗阻，根据固定瓣性环选用相对开口面积大的人工机械瓣．有利于改善血流动力学，各型号瓣膜应用对患者的早期康复无影响。     

动态三维超声心动图对正常和病变二尖瓣器的临床研究

目的探讨动态三维超声心动图对二尖瓣器评分的价值。方法通过多平面经食管三维超声心动图容积提取显示法（３ＤＶ）对２０例正常二尖瓣、８例二尖瓣狭窄、１２例二尖瓣关闭不全和１０例二尖瓣位人工机械瓣患者的二尖瓣器进行了评分,并与取自三维数据集的任意切面超声心动图（ＡＰＥ）和多平面经食管二维超声心动图（ＴＥＥ）对照。结果３ＤＶ对正常和病变二尖瓣的活动度、连合部、瓣口面积和与毗邻结构的空间关系的评分显著高于ＴＥＥ和ＡＰＥ（Ｐ＜０．０１和Ｐ＜０．０５）。３ＤＶ对病变二尖瓣的诊断价值更优于正常二尖瓣。它对瓣叶厚度、瓣环和瓣下结构的评分低于ＴＥＥ和ＡＰＥ（Ｐ＜０．０１）。三种检查方法对二尖瓣位人工机械瓣的评分无显著性差异（Ｐ＞０．０５）。结论３ＤＶ对评价正常和病变二尖瓣器提供了一种有特殊价值的新方法。     

多普勒超声心动图评价二尖瓣位人工生物瓣血流动力学性能

应用多普勒超声心动图技术对５５例置换于二尖瓣位的三种不同生物瓣的血流动力学指标进行了观察。结果表明，置换于二尖瓣位三种生物瓣的有效瓣口面积（ＥＯＡ）分别为：ＢＮ型２．６±０．４ｃｍ２，Ｐｅｒｆｅｃｔ型为２．３±０．２ｃｍ２，Ｃａｒｐｅｎｔｉｅｒ－Ｅｄｗａｒｄｓ瓣为２．３±０．６２ｃｍ，其中ＢＮ瓣的ＥＯＡ最大（Ｐ值＜０．０５），后两种瓣间的ＥＯＡ无显著差别（Ｐ值＞０．０５），三种生物瓣的峰值流速（Ｖｍａｘ）、峰值压差（ＰＧ）、及平均压差（ＭＧ）无显著差别（Ｐ值均＞０．０５）。     

多普勒超声检测置入人工心瓣的血流动力学

本文应用多普勒超声检测人工心瓣置换者６０例，正常人自然二尖瓣者２０例的血流速度，跨瓣压差，压差半降时间及有效瓣口而积。结果显示：人工心瓣的血流速度，跨瓣压差，压差半降时间，有效瓣口面积与正常自然二尖瓣有明显差异（Ｐ＜０．００１）。提出人工心瓣的压差半降时间明显延长或进行性延长，或有效瓣口面积小于１ｃｍ＾２，均提示人工心瓣口血流受阻。     

二尖瓣狭窄与心房纤颤：血流动力学与超声心动图研究

为探讨二尖瓣狭窄患者肺循环血流动力学、病程与心房纤颤之间的关系，利用心导管技术结合超声心动图测量８０例二尖瓣狭窄患者平均肺动脉压、左房压、右房压、跨瓣压、左右心室收缩压和舒张压、左室内径、左房内径、瓣口面积。结果表明：持续性房颤患者左房内径大于窦性心律患者（Ｐ＜０．０００１），也大于阵发性房颤患者（Ｐ＜０．０５），持续性房颤患者左右室舒张压和病程也明显大于窦性心律者。皮尔逊相关系数和多元逐步回归分析进一步证明，房颤与左房内径大小及病程长短有关。本文对心房纤颤发生机理进行初步探讨。     

经皮二尖瓣球囊成形术对N—心钠素分泌的影响

目的：探讨经皮二尖瓣球囊成形术（ＰＢＭＶ）对Ｎ心钠素（ＮＡＮＰ）分泌的影响。方法：研究了２４例二尖瓣狭窄（ＭＳ）患者ＰＢＭＶ前后血浆ＮＡＮＰ浓度，并与平均二尖瓣跨瓣压差（ＭＭＰＧ）、二尖瓣口面积（ＭＶＡ）、左房内径（ＬＡＤ）及血流动力学参数作相关分析。结果：ＭＳ患者术前血浆ＮＡＮＰ浓度高于对照组（Ｐ＜０．００１），术后显著下降（与术前比较，Ｐ＜０．００１），但仍高于对照组（Ｐ＜０．００１）。血浆ＮＡＮＰ改变量（ΔＮＡＮＰ）与ＭＭＰＧ改变量（ΔＭＭＰＧ，ｒ＝０．６７７０，Ｐ＜０．０００５）、ＬＡＤ的改变量（ΔＬＡＤ，ｒ＝０．４７０４，Ｐ＜０．０２５０）及平均左房压改变量（ΔＭＬＡＰ，ｒ＝０．７２７２，Ｐ＜０．０００５）均呈正相关，与ＭＶＡ的改变量（ΔＭＶＡ）呈负相关（ｒ＝－０．６４５１，Ｐ＜０．０００５）。结论：ＮＡＮＰ在ＭＳ引起的病理生理改变中起重要作用，测定ＮＡＮＰ变化有可能作为判定ＭＳ狭窄程度及ＰＢＭＶ疗效的一个指标。     

超声心动图对二尖瓣置换术后人工心脏瓣膜-患者不匹配的指导价值

目的:探讨运用超声心动图技术测算二尖瓣置换术(MVR)后人工心脏瓣膜-患者不匹配(PPM)现象的发生率以及PPM与术后早期血流动力学的关系.方法:比较320例不同种类、不同大小人工瓣膜MVR术后PPM发生率,PPM与术后早期血流动力学关系.结果:320例中机械瓣和生物瓣置换术后PPM的发生率分别为23.98％和54.05％;置换＞25 mm人工瓣膜213例,PPM发生率为21.13％,≤25 mm人工瓣膜107例,PPM发生率为50.47％.PPM组术后二尖瓣平均跨瓣压差和平均流速分别为(24.67±5.16)mmHg和(2.36±0.40)m/s,非PPM组分别为(12.52±2.26)mmHg和(1.21±0.32)m/s.结论:运用超声技术提示MVR术后PPM现象普遍存在,尤其是置换小号及生物瓣膜者;PPM影响术后早期患者的血流动力学改变.     

二尖瓣修复术后二尖瓣环形态的三维超声研究

目的：评价我院自行研制的新型软质人工二尖瓣成形环的临床应用效果,为软质人工二尖瓣环的推广应用提供理论依据。方法：应用体元模型经食管动态三维超声重建技术研究了１３例接受软质二尖瓣环成形术和９例硬质二尖瓣环成形术者,术后即刻二尖瓣瓣环形态和口径的变化。结果：应用硬质环行二尖瓣修复术后,从左心房向左心室方向观察,二尖瓣环形态被强制成与硬质环相似的“Ｄ”形,且二尖瓣环口径固定,在舒张末期和收缩末期二尖瓣环前后径分别为１．８０±０．１５ｃｍ和１．７７±０．１３ｃｍ（Ｐ＞０．０５）,二尖瓣环面积和周长均无显著性变化（Ｐ＞０．０５）;而应用软质环后,二尖瓣环仍呈椭圆形,在舒张末期和收缩末期二尖瓣前后径分别为２．０９±０．１９ｃｍ和１．８５±０．１３ｃｍ（Ｐ＜０．０１）,且其面积和周长均发生符合生理状态的周期性显著变化（Ｐ＜０．０１）。结论：应用软质二尖瓣成形环可维持人体二尖瓣环生理性的形态和功能。     

血流会聚法测二尖瓣机械瓣有效面积的价值

本研究通过经食管超声心动图对二尖瓣位机械瓣左房侧血流会聚现象的观察测量，利用血流会聚法对３７例经食管超声检查的二尖瓣换瓣术后患者二尖瓣机械瓣有效面积进行测定，并与压力半降法测定二尖瓣机械瓣有效面积进行比较，结果表明血流会聚法测定的二尖瓣机械瓣有效面积与压力半降法有良好相关（第一等速面ｒ＝０．８７，Ｐ＜０．０５；第二等速面ｒ＝０．７５，ｐ＜０．０５）。作者认为：血流会聚法是一种较有价值的测定二尖瓣机械瓣有效面积的方法。     

Assessment of normal and abnormal prosthetic mitral valves by Doppler echocardiography

Pulsed, continuous-wave, and color Doppler were performed in 165 normal mitral prostheses and 58 patients with prosthetic dysfunction (46 regurgitant and 12 obstructive valves) proved by catheterization and/or surgery. Mean mitral gradient (MG) and pressure half-time (PHT) were determined in all cases. Among normal prostheses, a wide range of both MG and PHT was observed in each type of valve and a considerable overlap between valves of different size. St-Jude's valve had the most optimal hemodynamics. Mild mitral insufficiency was detected in 14% of tissue and 24% of mechanical mitral valves. Repeat studies were performed in 30 patients over a 2.4 years period. Nine patients developed Doppler evidence of new prosthetic dysfunction, while Doppler parameters remained unchanged in 21 patients during the follow-up period. Among malfunctioning valves, Doppler correctly identified all cases of prosthetic obstruction (n=12), and 42 of 46 regurgitant valves. We conclude that Doppler echocardiography is a very useful technique in both non-invasive assessment and follow-up of normal prosthetic valves in the mitral position and in detecting prosthetic dysfunction, especially when prosthetic obstruction is present.     

彩色多普勒超声评价自制无支架带腱索生物二尖瓣功能

目的 评价自制无支架带腱索生物二尖瓣的临床应用效果。为无支架带腱索生物二尖瓣的推广应用提供理论依据。方法 用彩色多普勒超声心动图观察3例无支架带腱索生物二尖瓣替换术后心脏结构及血流动力学变化。结果 胸骨旁四腔心及左室短轴观极易观察到生物二尖瓣叶启闭运动，二尖瓣病变患者术后左房内径均较术前明显缩小，二尖瓣均无关闭不全‘；舒张期跨二尖瓣口峰值血流速度，平均血流速度，血流速度积分，峰值压差，平均压差和压力降半时间较术前明显改善，有效瓣口面积增加，但与自然瓣膜相比仍有差距。结论 无支架带腱索生物二尖瓣可维持人体二尖瓣生理功能，左室几何形状和血流动力学，彩色多普勒超声心动图在评价无支架带腱索生物二尖瓣替换术后的心脏结构和血流动力学方面有着较大的临床意义及实用价值。     

Comparison of transesophageal color flow Doppler imaging of normal mitral regurgitant jets in St. Jude Medical and Medtronic Hall cardiac prostheses.

Transesophageal color flow Doppler imaging of mitral mechanical prostheses is now widely used. This method eliminates the frequent problems of acoustic shadowing and flow masking that are commonly seen with a transthoracic Doppler study of mechanical mitral prostheses. Transesophageal color flow Doppler imaging was performed postoperatively in seven patients who had received St. Jude Medical mitral prostheses (St. Jude Medical, Inc., St. Jude, Minnesota) and in six patients who received Medtronic Hall mitral valves (Medtronic, Inc., Minneapolis, Minnesota). Maximal systolic regurgitant jet length and area determinations were obtained in all patients. A comparison of maximal jet lengths and areas for each type of mechanical prosthesis demonstrated that the Medtronic Hall prostheses produced longer maximal jet lengths (p = 0.0001) and larger jet areas (p = 0.0009) than those produced by the St. Jude Medical mitral valves. Medtronic Hall prostheses produce a large centrally directed jet, whereas St. Jude Medical prostheses typically generate three smaller jets. Recognition of these differences in transesophageal color flow Doppler images in these commonly used cardiac valve prostheses is necessary to avoid misinterpretation of the normally large systolic regurgitant jet of the Medtronic Hall prosthesis as representing prosthetic dysfunction.     

Prosthetic mitral regurgitation can be mimicked by Doppler color flow mapping: avoiding misdiagnosis.

OBJECTIVES: We sought to characterize a region of apparent systolic flow resembling mitral regurgitation (MR) in patients with mechanical disk mitral prostheses as artifact. BACKGROUND: Diagnosing MR in the presence of mechanical prostheses is challenging. Occasionally, important MR is suggested by a substantial region of systolic Doppler color flow in an acoustically shadowed region of the left atrium when, in fact, only trace MR exists. We hypothesized this pseudo-MR is caused by acoustic mirroring of the left ventricular outflow tract (LVOT) flow by sound reflected off the prosthesis, projecting flow into the left atrium because of longer transit time. METHODS: We reviewed 19 patients with mechanical mitral valves and trace MR by transesophageal echocardiography who had transthoracic echocardiography studies within 1 week (group A), and prospectively studied 22 consecutive patients by transthoracic echocardiography with subtle transducer angulation variation to detect pseudo-MR and characterize it by pulsed Doppler (group B). RESULTS: In group A, 12 of 19 patients had evidence of pseudo-MR on review of their transthoracic echocardiograms, absent by transesophageal echocardiography. In group B, this pseudo-MR signal was present in 13 of 22 patients, with velocity and timing by pulsed Doppler comparable with LVOT flow (onset at 125 +/- 27 milliseconds vs 135 +/- 11 milliseconds from QRS, P = not significant). The angle between the mitral plane and the LVOT, which determines whether this mirroring can occur, was smaller for patients with pseudo-MR. CONCLUSION: Artifactual pseudo-MR is often seen with mechanical mitral prostheses. Its behavior and sensitivity to geometric relationships are consistent with mirroring of LVOT flow. Practically, potential misdiagnosis can be readily avoided by pulsed Doppler sampling, sparing the patient further procedures.     

Hemodynamic performance of four mechanical bileaflet prosthetic valves in the mitral position: an echocardiographic study

Objectives: The CarboMedics, Duromedics, Sorin Bicarbon and the St. Jude Medical valves are bileaflet mechanical prostheses of modern but different design. Choosing a valve with the best hemodynamic profile is of clinical importance in patients with small ventricles and a small mitral annulus. Methods: The hemodynamic performance of these valves in the mitral position was compared in 76 asymptomatic, ambulatory patients with normally functioning prosthesis and left ventricle, using Doppler echocardiography. Of the 76 patients studied, 22 had the CarboMedics, 16 had the Duromedics, 17 had the Sorin Bicarbon and 21 had the St. Jude prosthesis. The patients ages ranged from 18 to 81 years. There were 44 women and 32 men. The time from implantation to echocardiographic study ranged from 1 to 55 months. Results: The echocardiographic study was performed earlier after surgery in the Sorin Bicarbon group. There was no significant difference in women/man ratio, incidence of atrial fibrillation, left ventricular or left atrial diameters between the four groups. The mean prosthesis size was significantly smaller for Sorin Bicarbon and Duromedics valves compared to the CarboMedics and the St. Jude valves (mean±SD, 27.2±1.3, 27.1±1.1 and 30.0±1.9 and 30.0±2.7 mm, respectively, P<0.001). Despite its smaller size the Sorin Bicarbon valve had significantly larger effective valve area by Doppler compared to the CarboMedics valve (290±40 vs 250±60 mm², respectively, P=0.014). The ratio of effective valve area to prosthesis size was significantly larger for the Sorin Bicarbon valve when compared with any other type of prosthesis. Conclusions: (1) The Sorin Bicarbon bileaflet valve offered the best hemodynamic results that may be explained by the valve's large leaflet opening angle and small thickness of the leaflets. (2) Since the Sorin Bicarbon is the newest bileaflet valve, durability of this valve remains uncertain.     

Analysis of Doppler-obtained velocity curves in functional evaluation of mechanical prosthetic valves in the mitral and aortic positions

A total of 145 patients with 160 mechanical prostheses of the Bj?rk-Shiley or Starr-Edwards type (15 with double mitral plus aortic valves) underwent clinical and Doppler echocardiography analysis. In the mitral position (85 valves) 10 patients with valve-related symptoms, calculated prosthetic area less than or equal to 1 cm2, or mean transprosthetic gradient greater than 10 mm Hg by Doppler echocardiography were predefined as abnormal. Seven patients had operations, and prosthetic obstruction was confirmed in all. All patients had higher pulmonary pressures (p less than 0.001) before valve replacement. Clinical presentation was variable; however, all those with proved prosthetic thrombosis had a fulminant course and distinctive velocity curves on Doppler. In the 75 patients predefined as normal, calculated valve area (2.3 +/- 0.6 cm2, mean +/- SD, range 1.3 to 3.7 cm2) and mean gradient (4.9 +/- 1.7 mm Hg, range 1.5 to 9.5 mm Hg) were widely spread and were independent of prosthetic size greater than or equal to 27 mm. Clinically 37 of 75 patients were moderately to severely limited. Mean gradient above 5 mm Hg was associated with a higher incidence of chronic atrial fibrillation (p less than 0.05), significant tricuspid regurgitation, failure of the right side of the heart, and significant functional limitation (p less than 0.02 for all). In the aortic position (75 valves) peak gradients were 28.2 +/- 15 mm Hg (8 to 80 mm Hg). Mean gradients were 18 +/- 9.6 mm Hg (6.5 to 46.5 mm Hg). Averaged gradients derived from the average of peak and late systolic gradients were 22.4 +/- 12.7 mm Hg (6 to 62 mm Hg). In all five abnormal patients (two with endocarditis and three with hemodynamic decompensation) but also in 18 of 70 clinically normal valves, peak gradients were greater than or equal to 36 mm Hg (ranges 36 to 65 mm Hg in both). Gradients were unrelated to symptoms or to the duration of the valve in situ (3 weeks to 20 years). Gradients correlated with prosthetic size (r = 0.57) and were higher (p less than 0.001) across small (19 to 23 mm) versus large (25 to 31 mm) valves. Regurgitation was present in 40% of the mitral prostheses. It was detected in 32% of the mitral prostheses defined as normal and was estimated as mild in most. Aortic regurgitation was present in all five abnormal aortic prostheses, significant in four, and in 26 of the valves (37%) defined as normal, significant in two.(ABSTRACT TRUNCATED AT 400 WORDS)     

Regurgitant flow in apparently normal valve prostheses: improved detection and semiquantitative analysis by transesophageal two-dimensional color-coded Doppler echocardiography

In 128 patients with apparently normally functioning prosthetic valves (n = 136) in the aortic position (n = 79) and the mitral position (n = 57), the prevalence of transprosthetic regurgitant flow was studied by use of transthoracic and transesophageal two-dimensional color-coded Doppler echocardiography. With the transthoracic approach, regurgitant flow was detected in early systole or diastole for 28% of the mitral prostheses and for 29% of the aortic prostheses. With transesophageal color-coded Doppler echocardiography, regurgitant jets were visualized for 95% of the mitral prostheses and for 44% of the aortic prostheses. In 40% of the Bj?rk-Shiley prostheses and 88% of the St. Jude Medical prostheses in the mitral position, more than one jet with an eccentric origin was detected, whereas in bioprostheses only one centrally localized regurgitant jet was noted. The regurgitant jet length was 22 +/- 2 mm in mitral prostheses and 12 +/- 2 mm in aortic prostheses. The jet area was 154 +/- 31 mm2 in mitral prostheses and 61 +/- 26 mm2 in aortic prostheses. Jets of this size and frequency have to be considered a normal finding and the equivalent of regurgitant flow known from in vitro studies. We conclude that only transesophageal color-coded Doppler echocardiography seems to be a reliable method for following up mitral valve prostheses to detect and differentiate regurgitant jets. For aortic valve prostheses the advantage of transesophageal color-coded Doppler echocardiography does not seem to be as obvious as the advantage for mitral prostheses.     

Microbubbles and mitral valve prostheses - transesophageal echocardiographic evaluation.

OBJECTIVE: To assess whether microbubbles are associated with a specific type of mitral valve prosthesis and to investigate the relationship of microbubbles to ventricular function and mitral regurgitation. One of the types of spontaneous echocardiographic contrast observed in patients with prosthetic heart valves has been described as microbubbles. METHODS: Clinical data and videotapes of patients with a prosthetic mitral valve who had undergone transesophageal echocardiography at the UCLA Medical Center between May 1989 and February 1995 were retrospectively reviewed. There were 109 studies (74 patients) available for review by two independent observers. RESULTS: Microbubbles occurred in 49 of the 66 studies of St. Jude valves ( 74%), eight of the 12 studies of Bjork Shiley valves (67%), four of four studies of Medtronic valves (100%) and zero of 23 studies of tissue valves (0%). Patients with an estimated ejection fraction greater than 45% were found to have a much higher likelihood of having microbubbles observed. There was no statistically significant association between the degree of mitral regurgitation and the observation of microbubbles. CONCLUSIONS: Microbubbles are a common phenomenon occurring in patients with mechanical mitral prostheses compared with tissue mitral valve prostheses. Their formation depends on the systolic ventricular function, suggesting a cavitation-like phenomenon participating in their formation perhaps due to the rate or velocity of the valve closure.     

Normal values of prosthetic valve Doppler echocardiographic parameters: a review

Doppler echocardiography plays an important role in the evaluation of patients with prosthetic valves. The evaluation of flow velocities across prosthetic valves is more complicated compared with native valves, and flow velocities are specific for various types, positions, and sizes of prostheses. Because all prosthetic valves are at least mildly stenotic and a significant proportion is regurgitant, information regarding normally functioning prosthetic valves is important. Eighteen studies resulting in data on 1105 patients with normally functioning prosthetic valves were reviewed. Significant differences among the various types and sizes of prosthetic valves were found in both the aortic and mitral positions. The results are summarized in tables and figures that can be used for reference in a clinical laboratory.     

Microbubbles associated with mitral valve prostheses in pediatric patients.

OBJECTIVES: To assess whether microbubbles are associated with mitral valve prostheses in children and to investigate their relationship to exercise. BACKGROUND: Bright, highly mobile echoes are seen in left heart chambers of patients with mechanical mitral valve prostheses. The clinical importance of those microbubbles is not yet known but they survive long enough to reach the cerebral circulation. No such studies have been reported in children. METHODS: There were 20 male and 10 female patients with a mean age of 10.4 years (range 2-16 years). Transthoracic echocardiography with calculation of cardiac output and ejection fraction was performed at baseline and after exercise following mechanical mitral valve replacement. Studies were evaluated for the presence of microbubbles. The mean time from operation to time of study was 18 months (range 0.2-89 months). RESULTS: Of the 30 children evaluated, 28 (93%) had evidence of microbubbles. Exercise increased the number of microbubbles in 15 of the 26 children. This was positively associated with an increase in cardiac output. CONCLUSIONS: (1) Microbubbles are commonly observed in children with mechanical mitral prostheses and are augmented by exercise. (2) This phenomenon is of a special concern in children due to their expected longevity with the prosthesis.