Vlahović A, Popović A
Institut za kardiovaskularne bolesti Dedinje Dr Aleksandar D. Popović, Beograd.
Med Pregl. 2000 Mar-Apr;53(3-4):146-53.
Hibernating myocardium is defined as a state of persistently impaired myocardial function, as a consequence of reduced coronary flow, which can be partially or completely reversed if the myocardial oxygen consumption/demand ratio is favorably altered. Since it indicates concordance between flow and function (flow-function relation), it can be concluded that hibernating myocardium, caused by reduced myocardial perfusion, improves its function after surgical revascularization, giving its detection a great clinical importance. Hibernating myocardium can be found in majority of patients with coronary artery disease and chronic left ventricular dysfunction. These patients, even without typical symptoms of angina, will benefit from myocardial revascularization. This beneficial effect is expressed by ejection fraction enhancement, which is directly proportional to the number of dysfunctional, but viable segments. Also, symptom improvement depends on the mass of revascularized myocardium, which is previously shown to be viable. Having that in mind, the mass of viable myocardium must be large enough, so that the degree of expected improvement of myocardial function after revascularization justifies the operation itself. Opposing this classical concept of hibernating myocardium, recent studies have shown that in patients with coronary artery disease, coronary flow at rest is normal or just slightly reduced, which cannot explain the degree of myocardial dysfunction. According to that, it is proposed that myocardial dysfunction is, like in myocardial stunning, the result of flow-function mismatch, meaning that pathophysiology of hibernating myocardium includes a component of stunning as well. Therefore, hibernating myocardium can be defined as a form of reversible left ventricular dysfunction, caused by chronic coronary artery disease, which is partially due to episodes of repetitive stunning and shows improvement after inotropic stimulation. From practical point of view, it is important to detect hibernating myocardium in all patients with coronary artery disease and left ventricular dysfunction, since their treatment and prognosis directly depend on whether the dysfunction is reversible or not. METHODS FOR IDENTIFICATION OF MYOCARDIAL VIABILITY: Detection of myocardial viability has great clinical importance, since both regional and global left ventricular function can significantly improve, either spontaneously or by myocardial revascularization. Noninvasive imaging procedures used for that purpose include positron emission tomography, thallium-201 imaging, technetium-99 imaging, dobutamine echocardiography and tissue characterization. Using these methods, it is possible to assess the presence of viable tissue through evaluation of metabolic activity, integrity of myocyte membrane and the inotropic reserve of myocardium.
冬眠心肌被定义为由于冠状动脉血流减少导致心肌功能持续受损的一种状态，如果心肌氧消耗/需求比得到有利改变，这种状态可部分或完全逆转。由于它表明血流与功能之间的一致性（血流-功能关系），可以得出结论，由心肌灌注减少引起的冬眠心肌在外科血运重建后其功能会改善，这使其检测具有重大临床意义。冬眠心肌可见于大多数冠心病和慢性左心室功能不全患者。这些患者即使没有典型的心绞痛症状，也会从心肌血运重建中获益。这种有益效果表现为射血分数增加，它与功能失调但存活的节段数量成正比。此外，症状改善取决于血运重建的心肌质量，此前已证明该心肌质量是存活的。考虑到这一点，存活心肌的质量必须足够大，以便血运重建后心肌功能预期改善的程度能证明手术本身是合理的。与这种经典的冬眠心肌概念相反，最近的研究表明，在冠心病患者中，静息冠状动脉血流正常或仅略有减少，这无法解释心肌功能障碍的程度。据此，有人提出心肌功能障碍与心肌顿抑一样，是血流-功能不匹配的结果，这意味着冬眠心肌的病理生理学也包括顿抑成分。因此，冬眠心肌可被定义为一种由慢性冠状动脉疾病引起的可逆性左心室功能障碍形式，部分原因是反复发生的顿抑发作，且在强心刺激后有所改善。从实际角度来看，在所有冠心病和左心室功能不全患者中检测冬眠心肌很重要，因为他们的治疗和预后直接取决于功能障碍是否可逆。心肌存活的识别方法：心肌存活的检测具有重大临床意义，因为无论是局部还是整体左心室功能都可自发或通过心肌血运重建得到显著改善。用于此目的的非侵入性成像检查包括正电子发射断层扫描、铊-201成像、锝-99成像、多巴酚丁胺超声心动图和组织特征分析。使用这些方法，可以通过评估代谢活性、心肌细胞膜完整性和心肌的变力储备来评估存活组织的存在。
