腺苷负荷实时心肌超声造影检测犬不同程度缺血心肌血流灌注

Adenosine stressing real-time myocardial contrast echocardiography on different grade of canine ischemic myocardium

目的探讨静息和腺苷负荷状态下实时心肌超声造影对犬不同程度缺血心肌检出的可行性。方法对12条健康杂种犬开胸,制作左前降支(LAD)不同程度狭窄动物模型。分别观察LAD狭窄前、中度狭窄、重度狭窄静息及腺苷负荷状态心肌显影情况。计算机分析得出不同状态下LAD供血区与对照区内造影剂微泡充填的时间-强度曲线及拟合曲线反映的A、β及A×β值。结果LAD中度狭窄时,腺苷负荷前LAD供血区心肌的血流量轻度减少,与对照区心肌相比差异无统计学意义(P>0.05);腺苷负荷后LAD供血区血流量明显减少,对照区血流量明显增加(P<0.001)。LAD重度狭窄时,腺苷负荷前LAD供血区心肌的血流量明显减少(P<0.05);腺苷负荷后LAD供血区心肌的血流量减少更明显,与负荷前LAD供血区相比差异有显著统计学意义(P<0.01),对照区心肌的血流量明显增加(P<0.001)。中、重度狭窄程度下,腺苷负荷后LAD供血区和对照区心肌的血流灌注对比均明显增强,LAD供血区和对照区间A×β值之比比负荷前均明显减小。结论静息状态下,心肌超声造影可检出重度心肌缺血,而难以检出中度心肌缺血;腺苷负荷心肌超声造影提高了心肌超声造影对缺血心肌的敏感性。

Objective To explore the feasibility of detecting different degree canine ischemic myocardium with myocardial contrast echocardiography （MCE） and adenosine stressing real-time MCE （RT-MCE）. Methods Twelve mongrel dogs were enrolled. Thoracotomy was performed and the left anterior descending arteries （LADs） were dissected free （0. 5-1.0 cm） from the adjacent tissues to produce midrange stenosis and severe stenosis. The resting and stressing myocardial MCE were observed before the coronary artery stenosis, the coronary artery midrange stenosis and the coronary artery severe stenosis. The MCE pictures were stored in the MO disk and analyzed by computer, the time-intensity curve and the fitting curve was made, from which the A, β and A× β of the myocardial region blood-supplied by LAD and the normal control region were obtained. Results With LAD midrange stenosis, the myocardial blood flow （MBF） of myocardial region blood-supplied by LAD decreased lightly, but no significant difference was found （P〉0.05）. After adenosine stressing, the MBF of the myocardial region blood-supplied by LAD decreased obviously, and the MBF of the normal control region increased obviously（P〈0. 001）. With LAD severe stenosis, the MBF of myocardial region blood-supplied by LAD decreased obviously, MBF was significantly different from the normal control region. After adenosine stressing, the MBF of the myocardial region bloodsupplied by LAD decreased more markedly, the MBF of the normal control region increased obviously （P〈0. 001）. In the two degree stenosis, the difference between the myocardial region bloofsupplied by LAD and the normal myocardial region became more obviously after adenosinestressing. The proportionality of A×β between the myocardial region blood-supplied by LAD and the normal control region diminished obviously after adenosine-stressing. Conclusion MCE can discover the severe ischemic region, but can not discover the midrange ischemic region of canine. Adenosine stressing MCE can discover the midrange ischemic region and increase the sensitivity of discovering the ischemic region.