Sakabe Y, Hishida H, Kawamura K, Murashima Y, Kodama K, Sugiura Y, Hagiwara K, Mizuno Y
Department of Internal Medicine, Fujita-Gakuen Health University School of Medicine, Toyoake.
J Cardiogr Suppl. 1987;12:49-58.
To evaluate myocardial tissue changes using two-dimensional (2D) echocardiography, several approaches were attempted. 1. Quantitative evaluation of the myocardial echo intensity by computerized image processing in patients with old anteroseptal myocardial infarction: 2D echocardiograms of the parasternal long-axis view were converted to digital images to measure the echo intensity of the regions of interest (ROI) placed in the interventricular septum (IVS), the left ventricular posterior wall (LVPW), the left ventricular cavity, and the pericardium. The mean value of the echo intensity was compared with that of the pericardium (maximum echo intensity) and of the left ventricular cavity as the minimum. In 12 normal subjects, the relative echo intensity of the IVS was 0.40 +/- 0.05 (mean +/- SE), whereas it was 0.71 +/- 0.06 in 11 patients with old MI (p less than 0.001). Color display facilitated the visual recognition of the numerical differences in echo intensities. 2. Evaluation of the myocardial echo intensity in acute phase of myocardial infarction: In nine normal elderly persons, the relative echo intensity of IVS was 0.29 +/- 0.14, and there was no significant change in the early stage (three to seven days) of acute infarction (0.31 +/- 0.14). Two weeks later, however, a significant increase was noted (0.61 +/- 0.10) (p less than 0.01), probably due to an increase in collagen fibers. 3. Changes of the myocardial echo intensity in acute myocardial ischemia: Two-dimensional echocardiograms were recorded in nine open-chest dogs using 3 and 5 MHz transducers before and 10 min, 1 hr, 3 hrs, and 6 hrs after coronary artery ligation. With the 5 MHz transducer, the echo intensity of the ischemic myocardium was decreased after 10 min and was remarkable after 1 hr (0.24 +/- 0.08), and restored in six hrs. These changes could not be detected using the 3 MHz transducer. 4. An in vitro study for assessment of ultrasonic attenuation in the canine infarcted myocardium: The frequency dependency of ultrasonic attenuation of the resected canine myocardium in the frequency region of 2 MHz to 7 MHz was estimated one and two weeks after coronary artery ligation. The distributions of attenuation characteristics were nearly consistent with those of collagen contents determined histologically. In conclusion, we demonstrated that acute and chronic ischemia of the myocardium influences the transmission and reflection of ultrasound. By applying this property, ultrasonic tissue characterization may become a useful tool for detecting myocardial ischemia in the near future.
为了使用二维（2D）超声心动图评估心肌组织变化，尝试了几种方法。1. 陈旧性前间隔心肌梗死患者心肌回声强度的定量评估：将胸骨旁长轴切面的2D超声心动图转换为数字图像，以测量放置在室间隔（IVS）、左心室后壁（LVPW）、左心室腔和心包的感兴趣区域（ROI）的回声强度。将回声强度的平均值与心包（最大回声强度）和左心室腔（最小回声强度）的平均值进行比较。在12名正常受试者中，IVS的相对回声强度为0.40±0.05（平均值±标准误），而在11名陈旧性心肌梗死患者中为0.71±0.06（p＜0.001）。彩色显示有助于直观识别回声强度的数值差异。2. 心肌梗死急性期心肌回声强度的评估：在9名正常老年人中，IVS的相对回声强度为0.29±0.14，在急性梗死早期（3至7天）无显著变化（0.31±0.14）。然而，两周后，出现显著增加（0.61±0.10）（p＜0.01），可能是由于胶原纤维增加。3. 急性心肌缺血时心肌回声强度的变化：使用3和5MHz换能器在9只开胸犬冠状动脉结扎前及结扎后10分钟、1小时、3小时和6小时记录二维超声心动图。使用5MHz换能器时，缺血心肌的回声强度在10分钟后降低，1小时后显著降低（0.24±0.08），6小时后恢复。使用3MHz换能器未检测到这些变化。4. 犬梗死心肌超声衰减评估的体外研究：在冠状动脉结扎后1周和2周，估计切除的犬心肌在2MHz至7MHz频率范围内超声衰减的频率依赖性。衰减特征的分布与组织学测定的胶原含量分布几乎一致。总之，我们证明了心肌的急性和慢性缺血会影响超声的传播和反射。通过应用这一特性，超声组织特征分析在不久的将来可能成为检测心肌缺血的有用工具。
