【作者】 杨源；

【导师】 李树清； AnthonyN.DeMaria；

【作者基本信息】 昆明医学院 ， 外科学， 2008， 博士

【摘要】 第一部分实时心肌声学造影评定冠脉储备及高血压,低氧血症对冠脉储备的影响目的:冠脉储备是诊断冠心病,评定冠心病治疗效果的重要指标,本文的目的:①研究经静脉实时心肌声学造影（MCE）评定冠脉储备的可行性;②应用实时心肌超声造影评定高血压对冠脉储备的影响;③应用实时心肌超声造影评定低氧血症对冠脉储备的影响。方法:采用18只非开胸的猪作为研究对象,应用商业设备进行实时心肌超声造影。图像采用左室乳头肌水平短轴平面,以30ml/h的速度连续滴注造影剂BR1（Sonovue）,每15个心动周期进行一次气泡导破（闪烁）,闪烁后的微气泡再充盈的时间强度关系可用公式Y=A(1-e^-bt)*c表示,从此公式可得到信号增加率b,用静息时的b参数去除滴注腺苷后的b参数所得到的商就为冠脉储备。同时用荧光微球技术进行冠脉储备的测定,作为冠脉储备的标准参照。这一部分的研究完成后,随机取其中9只猪作为研究对像,进行高血压对冠脉储备的影响的研究。观察血液动力学稳定后,取基线参数（包括心率,血压,动脉血气分析样本）,给予苯肾上腺素滴注,当收缩压达到200mmHg左右时,再次进行心肌造影及注入荧光微球,此后静注腺苷140μg/kg/min,大约2min后,再次进行心肌造影及注入荧光微球。取另9只剩下的试验猪作低氧血症对冠脉储备的影响的研究。血液动力学稳定后,取基线参数（包括心率,血压,动脉血气分析样本）,然后通过气管插管及呼吸机给以氮气吸入,达到人工低氧血症状态时,给以腺苷滴注,大约2分钟后,再次进行心肌造影及注入荧光微球。根据腺苷滴注前后的b参数求出冠脉储备参数,并与荧光微球计数求出冠脉储备值进行比较。结果:两种方法测得的冠脉储备有很好的相关性（P＜0.05）。其冠脉储备值类似,分别为2.5和3.1倍。苯肾上腺素使血压从平均129/100mmHg增加到平均196/153mmHg（P＜0.001）,心率由114增加到124 beats/min,心率变化无显著性差异。苯肾上腺素导至的血压增高增加静息时的b值,降低腺苷扩血管后的b值,使冠脉储备明显降低,由2.5倍降低为1.5倍,其差异有显著性（P＜0.05）。用荧光微球技术测定所得的冠脉储备也显著降低,由3.1倍降低为1.8倍（P＜0.05）。氮气吸入使平均氧分压明显降低,从平均120.6mmHg下降到平均51.8 mm Hg（1 mm Hg=0.133KPa,P＜0.001）,心率由114增加到116次/分（P＞0.05）。CFR也明显降低,分别从2.5倍降至1.5倍（MCE,P＜0.05）及3.1倍降至2.5倍（MFT,P＞0.05）,这是由于氮气吸入后静息时的心肌血流轻微增加,而腺苷滴注后的心肌血流较氮气吸入前腺苷滴注后的心肌血流轻度降低所致。结论:心肌声学造影是理想的无创性评定冠脉储备的方法,它简单易行,可重复进行。苯上腺素导至的血压增高明显降低冠脉储备值,这种降低无论是应用心肌声学造影方法还是荧光微球技术评定均类似。因此,在评定冠脉储备时血压因素必须加以考虑。因为即便没有高血压的病理基础,仅仅模拟交感神经兴奋也可使冠脉储备降低。氮气吸入导致的低氧血症不仅降低冠脉储备值,还降低MCE所评定的CFR值,也就是说当应用MCE评定低氧血症患者的CFR时,有可能低估冠脉储备,当应用MCE评定低氧血症时的CFR时,应该把这种影响因素加以考虑。第二部分应用冷冻方法制作试验鼠心衰模型目的:探讨应用冷冻损伤方法制作小鼠的心衰模型,为研究心力衰竭时血液动力学的改变及其发生机制以供实验依据。方法:89只小鼠随机分成3组（冷冻损伤组,冠脉结扎组,年龄对照组）,应用液氮探头对冷冻损伤组小鼠进行心肌的冷冻损伤处理,对冠脉结扎组小鼠进行冠脉结扎,并于术前,术后5周,术后10周分别对三组小鼠进行超声心动图检查,于试验终末时对冷冻损伤组,年龄对照组小鼠进行血液动力学研究,对冷冻损伤组的小鼠进行心肌疤痕大小的测定。结果:冷冻损伤组63%小鼠存活,均为严重心衰（FS＜30%）,冠脉结扎组47%存活,仅36.7%为严重心衰;术后五周两组小鼠的心功能的指标（FS,EF）均较术前明显降低,而左室舒张末径,收缩末径均较术前明显增大,其差异有显著性;但两组小鼠间术后5周上述指标比较没有显著性;冷冻损伤后5周的小鼠其心功能,左室腔的大小与术后10周比较未见显著性差异。冠脉结扎组术后五周与术后10周比较左室内径无显著差异,但心功能进一步下降,差异有显著性。冷冻损伤组的有创性血液动力学指标:最大dP/dt,最小dP/dt,心输出量,射血分数明显低于年龄对照组。结论:心肌冷冻方法是制作小鼠心力衰竭模型的理想方法,与冠脉结法相比,它存活率高,小鼠间的心衰程度差异小,其血液动力学指标与冠脉结扎法制作的心衰模型相似。它是制作小鼠心衰模型的一种理想方法。更多还原

【Abstract】 Background:Time-intensity curves derived from microbubble destruction/refilling sequences recorded from myocardial contrast echo（MCE） can provide parameters which correlate with coronary blood flow.The response of these parameters to adenosine（ADN） vasodilation correlates with coronary flow reserve （CFR） measured by microsphere techniques.However,no data exist regarding the effect of physiological variables such as blood pressure and oxygen tension upon the determination of CFR by MCE.Methods:Studies were performed in 18 closed chest swine.Low-energy, real-time MCE was performed in short axis papillary muscle view while infusing BR1（Sonovue,Bracco） at 30 ml/hr.High-energy FLASH frames destroyed bubbles every 15 cardiac cycles,and time-intensity curves derived from refilling were fitted to an exponential function as y=A(1-e^-bt) +C from which the rate of signal rise（b） was obtained.CFR was calculated as the ratio of b values prior to and after adenosine infusion,and was obtained during control（CON） and after increasing BP with phenylephrine in 9 out of the 18 pigs,and after inducing hypoxia by breathing nitrogen in another 9 pigs out of the 18 pigs.CFR was independently determined by fluorescent microspheres.Results:Adenosine produced a similar increase of CFR by MCE and microspheres（2.5 vs 3.1 respectively） during CON.Phenylephrine increased the mean BP from 129/107 to 196/153mmHg（P＜0.001） and changed heart rate from 114 to 124（P＞0.05）.Phenylephrine increased resting and decreased post adenosine values of b（0.71 and 0.92 respectively）,producing a marked reduction in CFR which was similar to that measured by microspheres（1.5 and 1.8 respectively,both P＜0.05）. Nitrogen inhalation decreased the mean PaO₂ from 120.6 to 51.8mmHg,（P＜0.001）, without a change of heart rate（114 to 116 beats/min）.The decrease of PaO₂ resulted in slightly increased resting values for both b（0.46 to 0.51） and MBF（1.39 to 1.72）, both nonsignificant,and slightly decreased values after adenosine:1.05 to 0.82 for b and 4.30 to 3.93 for MBF,both P＞0.05.Thus,CFR decreased with hypoxia:to 1.42 by b parameter,P＜0.05,and 2.5 by MBF（P＞0.05）.Conclusions::Trans-vein real-time MCE is a ideal method to assess coronary flow reserve.It is fissiable,repeatable.Phenylepherine induced hypertension and hypoxia reduces quantitative parameters of CFR derived from destroy/refill sequences by MCE.The influence of these variables must be taken into account when employing MCE to assess coronary flow reserve. Purpose:A standardized heart failure model was induced by cryo-injury.Methods:Cryo-injury was produced in anesthetized C57BL/6 mice via 10s of direct contact on the LV anterior free wall with a 4 mm Brymill liquid nitrogen chilled probe.MI was induced by coronary artery ligation. Echocardiograms of fractional shortening and LV end diastolic and systolic dimensions were made before（baseline）,35d and 70d post-injury.Also in-situ contractility and ejection fraction were assessed at 70d post-injury, and triphenyltetrazolium chloride（TTC） stain was used to delineate infarction.Gs protein and adenylyl cyclase content were test in by Western method in cryo-injury mouse and compared to normal heart.Results:The myocardial cryo-injury scar size determined by TTC stain was profoundly large（51±1%,n=9）.Echocardiographic and in situ parameters revealed a highly enlarged and dysfunctional heart.Both Gs protein and adenlyly cyclase were unchanged in the cryo-ingery group.Conclusion:cryo-injury created a more standardized mouse heart failure model and higher survival rate than coronary ligation did.Both Gs protein and adenlyly cyclase were unchanged when heart failure was developed.更多还原