Castro P F, Bourge R C, Foster R E
Catholic University of Chile, Santiago.
Am J Med. 1998 Jan;104(1):69-77. doi: 10.1016/s0002-9343(97)00312-4.
Patients with ischemic heart disease and significant left ventricular dysfunction are often difficult to manage medically. Revascularization procedures may improve left ventricular function and prognosis in this population if hypocontractile yet viable myocardium (hibernating myocardium) is demonstrated. Nuclear cardiology studies (single photon and positron methods), two-dimensional echocardiography, and magnetic resonance imaging studies have been utilized to identify hibernating myocardium. If thallium-201 studies are performed, the use of reinjection of thallium and repeat imaging improves the sensitivity of these studies for the detection of viable myocardium. Dobutamine echocardiographic studies may have a higher specificity and positive predictive value for the subsequent improvement of regional systolic left ventricular function after revascularization than the nuclear techniques. However, thallium studies have an excellent negative predictive value. Positron emission tomography (PET) allows the simultaneous assessment of perfusion and metabolic activity; however, these studies are expensive and not widely available. Functional evaluation with PET is in its infancy. Functional cardiac magnetic resonance imaging (MRI), although not widely available yet, provides the most accurate evaluation of regional ventricular function. MRI spectroscopy may be utilized to assess myocardial viability. As acquisition times improve and "real-time" imaging becomes a reality, MRI and MRI spectroscopy will likely become very accurate tools for assessing functional reserve and metabolic activity. The selection of the most appropriate method for assessment of myocardial viability will include consideration of a patient's characteristics, the presence of coronary arterial tree amenable to revascularization techniques, the techniques available to the clinician to assess viability, and local revascularization experience in this population. The result of an individual patient's evaluation is relevant to the consideration of coronary revascularization, or if this is not possible, cardiac transplantation.
患有缺血性心脏病且左心室功能严重不全的患者在药物治疗方面往往颇具难度。如果能证实存在收缩功能减退但仍存活的心肌（冬眠心肌），那么血运重建术或许可改善这类患者的左心室功能及预后。核心脏病学检查（单光子和正电子方法）、二维超声心动图以及磁共振成像检查已被用于识别冬眠心肌。若进行铊-201检查，采用铊再注射及重复成像可提高这些检查对存活心肌检测的敏感性。多巴酚丁胺超声心动图检查对于血运重建术后左心室局部收缩功能的后续改善，可能比核技术具有更高的特异性和阳性预测价值。然而，铊检查具有出色的阴性预测价值。正电子发射断层扫描（PET）可同时评估灌注和代谢活性；不过，这些检查费用高昂且尚未广泛应用。PET的功能评估尚处于起步阶段。功能性心脏磁共振成像（MRI）尽管目前尚未广泛应用，但能提供对局部心室功能最准确的评估。MRI波谱分析可用于评估心肌活力。随着采集时间的缩短以及“实时”成像成为现实，MRI和MRI波谱分析可能会成为评估功能储备和代谢活性的非常准确的工具。选择评估心肌活力的最合适方法将包括考虑患者的特征、适合血运重建技术的冠状动脉树的存在情况、临床医生可用于评估活力的技术以及该人群的局部血运重建经验。个体患者评估的结果与冠状动脉血运重建的考量相关，或者如果无法进行血运重建，则与心脏移植的考量相关。
