多巴酚丁胺负荷心肌声学造影评价冠状动脉狭窄

目的　为评价多巴酚丁胺负荷心肌声学造影 (MCE)诊断静息无血流限制冠脉狭窄的准确性。方法　在慢性冠脉狭窄闭胸犬模型上同步进行MCE和放射性微球测定心肌血流量 (MBF)。结果　负荷状态时 ,异常冠脉供血区 (MBF储备 <3)呈现灌注缺损 ,峰值声强度 (VI)较正常冠脉供血区低 (33± 13与 48± 14;P <0 0 1) ;且异常和正常冠脉供血区峰值VI比值 (0 7± 0 2 )与相应MBF比值呈良好的线性正相关 (r =0 86 ,P <0 0 0 0 1)。结论　多巴酚丁胺可作为一种负荷药物用于MCE评价冠脉狭窄     

对慢性闭胸犬评价潘生丁负荷心肌声学造影探测冠状动脉狭窄

目的 :为评价潘生丁负荷心肌声学造影 ( MCE)诊断静息状态无血流限制的冠脉狭窄的准确性。方法 :以安放“水膨胀式”缩窄器 ( Ameroid)的方法建立慢性多支冠脉狭窄犬模型 ,术后 7天～ 10天同步进行经外周静脉注射微泡法 MCE和放射性微球测定心肌血流量 ( MBF)。结果 :静息状态未见明显灌注缺损。负荷状态时 ,异常冠脉供血区 ( MBF储备 <3)呈现灌注缺损 ,峰值声强度 ( VI)较正常冠脉供血区低 ( 33± 13与 5 0± 12 ;P<0 .0 1) ;且异常和正常冠脉供血区峰值 VI比值 ( 0 .6± 0 .2 )与相应 MBF比值呈良好的线性正相关 ( r=0 .89,P<0 .0 0 0 1)。结论 :潘生丁负荷 MCE可用于临床定性和定量的评价静息状态无血流限制的冠脉狭窄     

双嘧达莫与多巴酚丁胺负荷心肌超声造影探测冠脉狭窄？…

目的 对比双嘧达莫和多巴酚丁胺负荷心肌超声造影（ＭＣＥ）探测静息状态下无心肌血流限制性冠脉狭窄的能力。方法 用放置“水膨胀”式缩窄器于冠脉主干近端的方法,建立１５只慢性多支冠脉狭窄闭胸犬模型。术后７～１０ｄ进行静息、双嘧达莫和多巴酚丁胺的小剂量微泡弹丸式注射法ＭＣＥ,并同步用放射性标记微球测量心肌血流（ＭＢＦ）。以ＭＢＦ储备≥３为正常和〈３为异常供血区。结果 两种药物引起ＭＢＦ增加,在正常和异常供     

多巴酚丁胺和腺苷对心肌血流速度和容积的影响及其评价冠脉狭窄的意义

目的　评价多巴酚丁胺和腺苷对冠脉微循环的直接效应。方法　建立 8条一支冠脉 (左前降支或左回旋支 )轻中度狭窄的犬模型 ,直接冠脉内输注多巴酚丁胺和腺苷。采用经外周静脉微泡连续输注法 ,在谐波和递增性间断超声发射下进行心肌声学造影 (MCE) ,测定微泡速度 (MV)和心肌血流容积 (MBV )。以放射性微球测定心肌血流量 (MBF)。结果　在正常冠脉供血区中 ,虽然两种药物引起MBF明显增加 [静息时 ( 1.1± 0 .4)ml/(min·g) ;输注多巴酚丁胺和腺苷时分别为 ( 3 .7± 1.2 )ml/(min·g)和 ( 4 .7± 1.0 )ml/(min·g) ] ,而MBV仅轻微增加 (分别为 13 % ,17% ) ,但是MV增加的程度与MBF相一致 (静息时 5 .0± 0 .9;多巴酚丁胺和腺苷分别为12 .3± 4.1,13 .8± 4.1)。在狭窄冠脉供血区中 ,虽然两种药物引起了一定程度的MBF增加 (P <0 .0 5 ) ,但MBV较静息状态降低 (P <0 .0 5 ) ;然而MV明显高于静息状态 (P <0 .0 5 ) ,两种药物间比较无差异。两种药物负荷时的MV比值 (狭窄 /正常 )与MBF比值之间有良好的线性相关 (P <0 .0 0 5 ,r分别为 0 .85和 0 .68)。结论　冠脉内直接输注多巴酚丁胺和腺苷时 ,两种药物对狭窄和正常冠脉供血区微循环的影响相似。因此 ,两种药物可在冠脉狭窄的评价中交互使用。     

VVI及对比超声评价犬冠状动脉狭窄时心肌灌注和舒张功能的关系

目的 应用速度向量成像(VVI)结合心肌声学造影(MCE)评价犬冠状动脉狭窄静息和负荷状态下心肌组织灌注和舒张功能的关系.方法 制作不同程度冠状动脉(前降支)狭窄模型8只,在冠状动脉狭窄前后于静息和多巴酚丁胺注射达峰值剂量时,取左心室短轴图像行VVI分析,并行MCE测量心肌血流量(A·β值)和短轴圆周方向上的舒张期峰值应变率(SRdia),评价二者之间的相关性.结果 静息状态下,冠状动脉轻、中度狭窄时,供血区SRdia和A·β值与正常区差异无统计学意义;重度狭窄时,供血区SRdia和A·β值均低于正常区(P<0.05).多巴酚丁胺负荷下,轻、中度冠状动脉狭窄时,供血区SRdia和A·β值即低于正常区(P<0.05);重度狭窄时,缺血区SRdia和A·β值较正常区降低得更加明显(P<0.05).无论静息还是负荷状态下,SRdia和A·β间均呈正相关(r静息=0.57,r负荷=0.72,P<0.01).结论 VVI技术能够用于评价短轴心肌节段舒张功能,且能在一定程度上反映心肌血流灌注的变化情况.     

多巴酚丁胺负荷超声和实时声学造影评价介入治疗术后心肌灌注

目的应用实时心肌声学造影和多巴酚丁胺负荷超声心动图,定量评价冠状动脉(冠脉)介入治疗术后心肌血流量和血流储备。方法12例前壁和前间隔心肌梗死患者,在心肌梗死后3周至1年择期行冠脉造影和支架介入术,在介入术后1周,在基础状态下和多巴酚丁胺负荷试验时进行实时声学造影。应用Qlab软件定量分析实时声学造影再灌注曲线,得到曲线平台值(A)、曲线上升速度(β)和A·β(心肌血流量,MBF),以及各参数的储备值。结果负荷试验时的室壁运动指数明显下降(1.45±0.24对1.25±0.18,P<0.05),左室射血分数显著增加[(45.74±8.45)%对(59.80±11.92)%,P<0.05]。静息状态和负荷时,正常冠脉供血节段的A、β和MBF均显著高于病变冠脉供血区(均P<0.05)。与静息时相比,负荷时正常冠脉供血节段的A、β和MBF显著增加(均P<0.001),病变冠脉供血区的A、β和MBF也明显上升(均P<0.01),但增加幅度不及正常冠脉供血区(P<0.05)。除A值储备外(P=0.17),病变冠脉供血区的β和MBF的储备均明显低于正常冠脉供血区(P分别为1.06×10-7,7.66×10-5)。存活心肌节段β及MBF储备明显高于梗死心肌节段(均P<0.05)。结论心肌梗死患者在择期介入治疗术后仍存在心肌灌注异常和室壁运动障碍,多巴酚丁胺负荷实时声学造影能够有效地定量心肌血流量和检测存活心肌,有助于判断心肌的血流储备能力,为临床评价冠心病提供了简便、可靠、无创伤性的新方法。     

不同剂量多巴酚丁胺对正常心肌纵向收缩期峰值应变的影响

目的 探讨不同剂量多巴酚丁胺对正常人纵向收缩期峰值应变的影响.方法 对11例冠状动脉造影正常或狭窄＜50％的正常人,进行大剂量多巴酚丁胺负荷试验.分别在静息状态、5、10、20、30和40 μg/ (kg·min)测定左室各心肌节段心内膜下心肌的纵向收缩期峰值应变并进行统计学分析.结果 在静息状态下及各级负荷状态下左室心肌纵向收缩期峰值应变从基底段至心尖段逐渐增加.在心尖段,后间隔和下壁的纵向收缩期峰值应变值大于其他节段;在中间段,下壁和前间隔的纵向收缩期峰值应变值大于其他节段;在基底段,前壁和后壁的纵向收缩期峰值应变值大于其他节段.多巴酚丁胺负荷试验中,心肌各节段的纵向收缩期峰值应变值随着多巴酚丁胺剂量的增加而增加,大多数节段在多巴酚丁胺剂量20 μg/ (kg·min)时达到峰值,个别节段多巴酚丁胺剂量30 μg/ (kg· min)时达到峰值,峰值纵向收缩期峰值应变与同组静息状态比较,差异有统计学意义(P＜0.05);多巴酚丁胺剂量40 μg/ (kg·min)时,大多数节段纵向收缩期峰值应变与静息状态比较轻度下降,个别节段稍增高,差异无统计学意义(P＞0.05).结论 正常心肌节段的纵向收缩期峰值应变随着多巴酚丁胺负荷剂量的增加而增加,但当剂量达到40 μg/ (kg·min)时,开始恢复到静息水平或有所降低.     

心肌灌注造影在多巴酚丁胺负荷前后早期诊断冠心病的临床研究

目的探讨心肌灌注造影(MCE)技术在大剂量多巴酚丁胺负荷前后早期诊断冠心病的价值.方法 对临床疑为冠心病患者38例,进行大剂量多巴酚丁胺负荷超声心动图试验,分别在静息状态和多巴酚丁胺负荷超声心动图试验终止时即刻行MCE检查.以冠状动脉造影为金标准将大剂量多巴酚丁胺负荷超声心动图前后心肌灌注状态目测法对冠心病的检出率进行比较.结果 多巴酚丁胺负荷超声心动图检查的38例患者中,9例(24%,9/38)达到峰值负荷水平,22例(58%,22/38)达到中级负荷水平.其中通过冠状动脉造影诊断的27例冠心病患者在多巴酚丁胺负荷前后,通过心肌灌注状态目测法诊断心肌缺血患者的例数分别为10例(37%,10/27)及24例(89%,24/27,χ2=15.565,P＜0.01).结论 大剂量多巴酚丁胺负荷超声心动图结合MCE可提高缺血心肌的检出率,发现隐匿性心肌缺血,为临床无创性诊断早期冠心病患者提供新方法.     

心肌声学造影评价冬眠心肌灌注改变的实验研究

目的　评价慢性冬眠心肌毛细血管水平心肌灌注的改变。方法　在 2 2只犬中造成冠脉左前降支内径 5 0 %的缩窄 ,1个月后在存活犬中进行小剂量多巴酚丁胺超声心动图负荷试验 ,于用药前及负荷时进行心肌声学造影 (MCE) ,测量冬眠节段与正常节段之间MCE峰值强度的比值 (PIr)、时间强度曲线下面积的比值 (AUCr)、峰值减半时间的比值 (HTr)以及平均通过时间的比值 (MTTr) ,并以高频探头测量左前降支狭窄远端的冠脉血流储备。结果　在 10只犬中成功建立了慢性心肌冬眠的动物模型 ,与基础状态相比 ,负荷状态室壁运动改善后 ,PIr和AUCr显著增加 (P <0 .0 5 ) ,HTr和MTTr显著减小 (P <0 .0 5 )。负荷状态 (S)与基础状态 (B)下上述指标的比值S/BPIr和S/BAUCr均与左前降支狭窄远端的冠脉血流储备十分相近。结论　①基础状态下冬眠节段心肌灌注较正常节段减少约 5 0 % ,负荷状态下心肌灌注虽显著增加但仍低于正常节段 ;②MCE是评价冬眠心肌血流灌注的可靠技术。     

双嘧达莫负荷超声心动图探测冠状动脉狭窄的病理生理基础

目的 探讨双嘧达莫负荷超声评价冠状动脉狭窄的病理生理基础,方法 双嘧达莫负荷超声评价慢性冠脉狭窄犬的室壁增厚率（％WT）,放射性微球定量心肌血流量（MBF）,结果 负荷状态,MBF储备＜2的心肌节段％WT减小;2小于等于MBF储备＜3的节段％WT无明显变化,而BF储备大于等于3的节段％WT反而增加,结论 狭窄冠脉MBF储备的异常程度可能是双嘧达莫负荷超声评价冠脉狭窄的主要病理生理基础。     

多巴酚丁胺负荷超声心动图结合心肌灌注造影早期诊断冠心病的价值

目的 探讨大剂量多巴酚丁胺负荷超声心动图(DSE)结合心肌灌注造影(MCE)技术早期诊 断冠心病的价值。方法 对临床可疑冠心病的38例患者进行大剂量多巴酚丁胺负荷试验,分别在静息状态和试验终止的即刻实行MCE检查。并在静息状态及各级负荷状态下观察室壁运动(WM)情况;对每次MEC后各心肌节段灌注状态进行评估。大剂量DSE时,以冠状动脉造影为金标准比较WM目测法和心 肌灌注状态目测法诊断冠心病的敏感性和特异性。结果 DSE时,9例(24％)患者达到峰值负荷水平,22 例(58％)达到中级负荷水平。DSE终止时,通过心肌灌注状态目测法及WM目测法诊断有心肌缺血患者 的例数分别为24例(89％)及15例(52％)(P＜0.01)。同时,通过上述两组方法评估心肌缺血,并根据相应缺血心肌节段所对应冠脉分支准确判断病变血管的敏感性分别为71％及41％(P ＜0.01)。结论 大剂量DSE结合心肌灌注造影可以提高检出缺血心肌的敏感性,发现隐匿性心肌缺血,为临床诊断早期冠心 病患者提供了无创性新方法。     

心肌超声造影对冠状动脉介入治疗术后心肌血流再灌注的临床研究

目的 探讨心肌超声造影(MEC)对冠状动脉介入治疗(PCI)术后心肌血流再灌注定量分析的价值.方法 对15例冠心病患者分别于PCI术前及PCI术后在对比脉冲序列成像条件下行心肌超声造影检查.采用自动追踪增强定量分析软件进行分析.得出造影剂强度(A)、斜率(β)、A×β、造影剂到达时间(AT)及达峰时间(TTP).结果 所有患者均获得清晰的左心室显影.正常灌注区均获得较满意的心肌显影,而缺血区心肌显影不良.异常灌注区域AT、TTP均较正常灌注区域延长,而A×β则显著减小(P＜0.05);单支冠脉狭窄＞70%息者PCI术后的A、β及A×β较术前明显改善(P＜0.05),而冠脉狭窄＜70%患者的A、β及A×β无明显变化(P＞0.05).结论 PCI可以有效改善病变心肌节段的微循环,心肌超声造影能够准确、快速、有效地评价PCI术后心肌再灌注情况.     

Quantification of myocardial perfusion and determination of coronary stenosis severity during hyperemia using real-time myocardial contrast echocardiography

Although regional myocardial perfusion can be currently quantified with myocardial contrast echocardiography (MCE) by using intermittent harmonic imaging (IHI), the method is tedious and time-consuming in the clinical setting. We hypothesized that regional myocardial perfusion can be quantified and the severity of coronary stenosis determined during hyperemia with MCE using real-time imaging (RTI) where microbubbles are not destroyed. Six open-chest dogs were studied during maximal hyperemia induced by adenosine in the absence or presence of coronary stenoses varying from mild to severe. Myocardial blood flow (MBF) was measured at each stage by using radiolabeled microspheres. MCE was performed using both IHI and RTI. Data for the latter were acquired in both end-systole and end-diastole. No differences were found between myocardial flow velocity (MFV) derived from IHI and RTI when end-systolic frames were used for the latter. MFV was consistently higher for RTI (P <.01) when end-diastolic frames were used. A linear relation was noted between MFV and radiolabeled microsphere-derived MBF ratios from the stenosed and the normal beds when end-systolic frames were used for RTI (r = 0.78, P <.001), whereas no relation was found when end-diastolic frames were used (r = 0.08, P =.78). The scatter for assessing MBF (A.beta) was minimal for IHI and RTI (9%-10%) with end-systolic frames, whereas that for RTI with end-diastolic frames was large (30%). Furthermore the correlation with radiolabeled microsphere-derived MBF was significantly (P <.01) weaker with RTI when end-diastolic frames were used (r = 0.53) than when end-systolic frames (r = 0.94) or IHI was used (r = 0.99). Data acquisition for IHI was 10 minutes, whereas it was 8 seconds for RTI. Thus, RTI can be used to quantify regional myocardial perfusion and stenosis severity during MCE. Only end-systolic frames, however, provide accurate data. RTI offers a rapid and easy means of assessing regional myocardial perfusion with MCE.     

Direct effects of dobutamine on the coronary microcirculation: comparison with adenosine using myocardial contrast echocardiography.

The direct effects of dobutamine on capillary blood volume (VOL) and blood flow velocity (VEL) are not known. We hypothesized that these would be more similar to that of adenosine because of its effects on the beta(2) receptors on the coronary circulation. A total of 9 open-chest anesthetized dogs were studied after placement of 2 noncritical stenoses at rest and during separate intracoronary administrations of 5 microg/kg(-1)/min(-1) of adenosine and 2 microg/kg(-1)/min(-1) of dobutamine. VOL and VEL were measured using myocardial contrast echocardiography, wall thickening with 2-dimensional echocardiography, and myocardial blood flow (MBF) with radiolabeled microspheres. Dobutamine increased the rate-pressure product significantly, whereas adenosine had no effect on the rate-pressure product. In the normal myocardium, adenosine had no effect on VOL and increases in MBF were all a result of increases in VEL. Dobutamine also caused mostly an increase in VEL and only a 30% increase in VOL indicating modest capillary recruitment. In the bed with stenosis both drugs attenuated increase in MBF by the same amount, which was associated with an attenuation in the increase in VEL secondary to a 15% increase in capillary resistance because of capillary derecruitment. The MBF-wall thickening relation was described for both drugs by the same function: y = 1 - exp(x) with wall thickening being significantly higher for dobutamine compared with adenosine for each level of MBF. We conclude that the increase in MBF in the normal myocardium with intracoronary dobutamine occurs mostly from an increase in VEL rather than from an increase in VOL. In the bed with a noncritical stenosis, the increases in MBF and VEL are similar for both drugs. Similar to intracoronary adenosine, intracoronary dobutamine also caused capillary derecruitment distal to a noncritical coronary stenosis.     

潘生丁心肌声学造影估价冠脉储备的实验研究

将８条犬左旋支冠脉（ＬＣＸ）临床缩窄，于主动脉根部快速注入声振７６％复方泛影葡胺行心肌声学造影（ＭＣＥ），并结合潘生丁试验，探讨播生丁ＭＣＥ定量指标估价冠脉储备的价值。结果提示：潘生丁试验后ＬＣＸ血流量及后壁峰值呈下降趋势，而前壁峰值则呈上升趋势（Ｐ＞０．０５）；前、后壁潘生丁试验后与试验前峰值比间有显著差异；潘生丁试验后与试验前ＬＣＸ血流量比与后壁峰值比间无显著差异，两者间相关系数为０．６５。结论：ＭＣＥ潘生丁试验后与试验前峰值比能作为一项估价冠脉储备的指标。     

Quantification of transmural gradient of blood flow in myocardial ischemia with real-time myocardial contrast echocardiography and dipyridamole stress test

Transmural redistribution of myocardial blood flow (MBF) is the earliest sign of myocardial ischemia. We aimed to evaluate the ability of real-time myocardial contrast echocardiography (MCE) combined with dipyridamole stress to quantify the transmural gradient of MBF during graded coronary stenosis. Real-time MCE was performed in 14 open-chest dogs at seven experimental stages: baseline; hyperemia induced by 6-min infusion of dipyridamole; 50%, 75% and 90% reduction of hyperemic flow after constriction in each stage for 10 min; reperfusion for 10 min; and subtotal occlusion of the left anterior descending coronary artery (LAD) for 90 min. We obtained MCE perfusion parameters from subendocardial (A-endo, beta-endo and A x beta-endo) and subepicardial (A-epi, beta-epi and A x beta-epi) layers of the ventricular septum and calculated their transmural gradients (A-EER, beta-EER and A x beta-EER) and systolic wall thickening (SWT). The sensitivity and specificity of each parameter for predicting 75% reduction of hyperemic flow, which was defined as mild myocardial ischemia, were derived by receiver operating characteristic (ROC) curve analysis. No transmural gradients were found at baseline; during maximal hyperemia and 50% reduction of hyperemic flow. beta-endo, A x beta-endo, beta-EER and A x beta-EER decreased significantly when the hyperemic flow was reduced by 75% or more. In contrast, SWT remained unchanged until the hyperemic flow was reduced by 90%. Among all parameters measured, beta-EER and A x beta-EER had the highest and SWT the lowest sensitivity and specificity in predicting mild myocardial ischemia. In conclusion, real-time MCE combined with dipyridamole stress allows for quantification of the transmural gradient of MBF. beta-EER and A x beta-EER are more sensitive than SWT and other MCE parameters in detecting mild myocardial ischemia.