Detection of viable myocardium by dobutamine and dipyridamole stress echocardiography.
Detection of viable myocardium by dobutamine and dipyridamole stress echocardiography.
复制标题
通过多巴酚丁胺和双嘧达莫负荷超声心动图检测存活心肌。
作者：
E. Picano;Bento de Sousa Mj;de Moura Duarte Lf;A. Pingitore;R. Sicari
细胞行为的基本方面是区域功能，这是通过应激回波识别活性的线索。根据定义，该功能在存活部分和坏死段都受到抑制。然而，只有可存活的节段保持收缩储备；正如几项实验研究一致表明的那样，正性肌力挑战可以引起收缩储备，无论是肠易激还是血流调节。这是药理负荷超声心动图识别存活能力的基础。多巴酚丁胺和双嘧达莫都利用了相同的病理生理学原理：活组织有剩余的收缩储备，这可以由适当的变力刺激引起。对于多巴酚丁胺，刺激是β受体介导的对心肌细胞的影响，后来又与流量的增加相匹配。对于潘生丁，主要刺激是腺苷A2受体介导的对冠状动脉小动脉平滑肌细胞的作用，导致流量增加。在这一点上，根据已知的心肌收缩能力和冠脉血流灌注之间的关系，功能的增加是可以预期的。从技术角度看，“存活窗”与多巴酚丁胺剂量相关，与双嘧达莫时间相关--相同剂量与早期变力阶段和随后的缺血反应相关。尽管有不同的病理生理背景和技术模式，多巴酚丁胺和双嘧达莫在预测存活率方面显示出类似的敏感性和特异性，总体准确性仅略低于静止的铊。这些观察的实际和临床影响仍然因为在高度精选的人群中进行的相对较少的观察而变得迟钝，其中包括有限数量的患者和极少数中心的研究。
The basic aspect of cell behaviour that is the clue for viability recognition by stress echo is regional function. By definition, the function is depressed both in viable and in necrotic segments. However, only viable segments retain a contractile reserve; which can be evoked by an inotropic challenge, either cathecolaminic or flow-mediated, as consistently shown by several experimental studies. This is the basis of viability recognition by pharmacological stress echocardiography. Both dobutamine and dipyridamole exploit the same pathophysiological principle: viable tissue has a residual contractile reserve, which can be elicited by an appropriate inotropic stimulus. With dobutamine, the stimulus is a beta-receptor mediated effect on myocardial cell, which is later matched by an increase in flow. With dipyridamole, the primary stimulus is an adenosine A2-receptor mediated effect on the coronary arteriole smooth muscle cell, leading to an increase in flow. At that point, the increase in function is to be expected on the basis of the known relationship between myocardial contractility and coronary perfusion. From the technical point of view, the "viability window" is dose-related with dobutamine, and time-related with dipyridamole--where the same dose is associated to an early inotropic phase followed by a later ischemic response. In spite of the different pathophysiological background and technical modalities, dobutamine and and dipyridamole have shown a similar sensitivity and specificity for prediction of viability, with an overall accuracy only marginally lower than resting thallium. The practical, clinical impact of these observations is still blunted by relatively small numbers of observations in highly selected populations including a limited number of patients and studies in very few centers.(ABSTRACT TRUNCATED AT 250 WORDS)