Noninvasive characterization of stunned, hibernating. The approach to diagnosis and therapy of hibernation, the clinical syndromes associated with stunned or hibernating myocardium, the role of nuclear imaging, dobutamine echocardiography, and cardiac magnetic resonance imaging to assess myocardial. Hibernating myocardium should be suspected in all patients with cad and chronic lv dysfunction of any degree, regional and global. Role of norepinephrine in development of shortterm.
Ms may follow successful thrombolytic therapy in evolving acute mi, percutaneous transluminal. Mechanism of contractile dysfunction in stunning hibernating myocardium is a state of persistently impaired myocardial and left ventricular function at rest due to reduced coronary blood flows. The term myocardial hibernation was first coined by rahimtoola when commenting on the results of the large randomised trials of coronary artery surgery. Choice b myocardial stunning is a less severe form of ischemiainduced reversible loss of contractile function than hibernation. Pathophysiologic basis of hibernating myocardium clinical gate. A term of art for prolonged, nonpermanent, postischaemic, systolic and or diastolic ventricular dysfunction without myocardial necrosis. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. In cardiology, hibernating myocardium is a state when some segments of the myocardium exhibit abnormalities of contractile function. Usmle step 1 questions at life and times in schools of medicine inc. Progression of myocardial hibernation to cell death will lead to unfavourable remodelling, and recovery from hibernation or stunning the reverse. Calvert phd, in cellular and molecular pathobiology of cardiovascular disease, 2014.
Jan 01, 2010 the first clinical implications of cardiac stunning were acknowledged already in 1975, when heyndrickx argued that the electrophysiologic recovery in synchrony with mechanical recovery in stunned myocardium would have implications for potential arrhythmogenicity, excitationcontraction coupling, and clinical assessment of myocardial viability. Sep 27, 2016 usmle step 1 questions at life and times in schools of medicine inc. Oct 29, 2017 hibernating myocardium is heart muscle that does not pump normally because of decreased blood flow, usually from a coronary artery blockage or heart attack. Stunning, hibernation, and calcium in myocardial ischemia. Stunned vs hibernating myocardium jama jama network. Intermittent ischemia and stunning appear to characterize hibernating myocardium. On f18 fdg pet, hibernating myocardium demonstrates metabolism tracer uptake at levels equal or even more intense than the normal myocardium. In myocardial stunning ms, the myocardium is viable and has contractile reserve. Myocardial stunning is the reversible reduction of function of heart contraction after reperfusion not accounted for by tissue damage or reduced blood flow. S canning the literature for chronic left ventricular dysfunction, the reader is puzzled by the fact that stunning and hibernation are often used alternately to address the issue of viability of chronic dysfunctioning myocardial segments in patients with ischaemic heart disease and therefore intrigued whether these two entities might represent two faces of the same disease. Hearts were removed from rats and set up as isometrically beating or shortterm hibernation models. They proposed that myocardial stunning may be thought of as a hit an. Stunned myocardium is defined as viable myocardium that exhibits prolonged postischemic dysfunction. Myocardial stunning cardiovascular research oxford.
Myocardial hibernation and stunning, which can be differentiated in clinical practice only by their rate of recovery with treatment, are not stable states. Myocardial stunning and hibernation statpearls ncbi bookshelf. Myocardial stunning or hibernating myocardium youtube. Initial studies, although favorable, lacked sufficient power and sample size to provide conclusive outcomes of viability. This phenomenon has been observed both in experimental animal models and, more recently, in man. Although myocardial contraction is depressed, metabolic balance is maintained, myocytes remain viable and myocardial contraction can be restored with myocardial revascularization. Editorial from the new england journal of medicine hibernation and stunning of the myocardium. New paradigms of coronary artery disease hibernation. Basics of myocardial viability, stunned and hibernating myocardium and modalities of its assessment, mechanism of each modality and its compatision slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. Myocardial stunning is a well defined phenomenon that is the result of an acute ischemic insult 15. Myocardial hibernation an overview sciencedirect topics. However, the statement pertaining to postinfarction cardiogenic shock that acute revascularization. Effects of coronary revascularisation on myocardial blood.
This results in the electromechanical uncoupling of energy generation from contraction that characterizes myocardial stunning. If, however, myocardial stunning is severe, involves large parts of the left ventricle and thus impairs global left ventricular function, it can be reversed with inotropic agents and procedures. Myocardial hibernation implies the concept of tissue viability, which can be diagnosed by imaging modalities that detect either the presence of contraction reserve or the persistence of metabolic activity within chronically dysfunctional myocardial regions see kim and shah on page 7. The original definition did not specify whether there was an abnormality in resting myocardial blood flow. Stunning, hibernation, and calcium in myocardial ischemia and. These abnormalities can be visualised with echocardiography, cardiac magnetic resonance imaging cmr, nuclear medicine pet or ventriculography.
May 05, 2014 it is now widely believed that repetitive episodes of stunning i. Although myocardial ischemia was once thought to result in irreversible cellular damage, it is now demonstrated that in cardiac tissue, submitted to the stress of oxygen and substrate deprivation, endogenous mechanisms. A 72yearold woman underwent a restvasodilator stress ecggated 99m tcspect myocardial perfusion imaging mpi. To investigate the role of norepinephrine in the development of shortterm myocardial hibernation. While shortterm hibernation was originally hypothesized to be the mechanism of chronic hibernating myocardium, it is now clear that shortterm hibernation is an extremely tenuous condition, with small increases in myocardial oxygen demand precipitating recurrent ischemia and a rapid deterioration in function and metabolism. Jun 29, 2018 hibernating myocardium is viable, and this viability can be determined with a variety of imaging techniques that depict either the presence of myocardial tissue that contracts if stimulated appropriately or the persistence of metabolic activity within the region of dysfunctional myocardium. Core topics in cardiac anesthesia, edited by jonathan h mackay and joseph e arrowsmith, 2nd ed. It is differentiated from the reversible dysfunction associated with chronic ischemia, which is called hibernation. Delineation of myocardial stunning and hibernation by positron emission tomography in advanced coronary artery disease. Myocardial stunning an overview sciencedirect topics. Stunned myocardium has clearly been documented a in experimental studies of brief coronary artery occlusion followed by reperfusion, and b in myocardial infarct models in. Decreased myocardial contraction occurs as a consequence of a reduction in blood flow. On myocardial perfusion imaging tc99m sestamibi or tc99m tetrofosmin spect, or rb82 or n ammonia pet, myocardial ischemia or infarct is suggested by a perfusion defect low tracer uptake. Ischaemic left ventricular lv dysfunction can arise from myocardial stunning, hibernation, or necrosis.
Imaging modalities have become frontline methods in the assessment of viable myocardial tissue, with the aim to stratify patients into optimal treatment pathways. Latisom offers a video streaming question bank for usmle step 1 a. Brief ischemic episodes 30 minutes followed by reperfusion can produce myocardial stunning, and full recovery is usually over hours to days. Myocardial stunning is defined as the mechanical dysfunction that persists after reperfusion despite the absence of irreversible damage. The concept of hibernation implies a downregulation of contractile function as an adaptation to a reduction in myocardial blood flow that serves to maintain myocardial integrity and viability during persistent ischemia. Hibernating myocardium represents a chronic myocardial dysfunction at rest associated with reduced coronary perfusion.
Pdf epub stunning, hibernation, and calcium in myocardial ischemia and reperfusion pp 251280 cite as. Objective previous studies have suggested that resting myocardial blood flow is within normal limits in most chronically dysfunctional left ventricular segments which improve function after coronary artery revascularisation hibernating myocardium. Stunning is potentially an important complication of myocardial reperfusion. The clinical importance of stunning may have been overestimated i in view of necessity of treatment of stunning only when global left ventricular function is grossly impaired, ii many patients with ischaemic heart disease are already using antiischaemic drugs that antagonize triggers of myocardial stunning e. Pdf myocardial stunning is a temporary postischemic cardiac mechanical dysfunction. Detailed analyses of regional myocardial blood flow, function, metabolism and morphology in ischemic and reperfused myocardium have led to the identifi cation of important phenomena, i. A wall motion abnormality at rest which improves during a. We investigated the effects of coronary artery bypass grafting cabg without cardiopulmonary bypass cpb in selected patients with severe hibernating myocardium. Read stunning, hibernation, and calcium in myocardial ischemia and reperfusion by available from rakuten kobo.
Acute, coronary occlusion causes a rapid decline within seconds in ventricular performance. The aim of this study was to assess myocardial blood flow and coronary vasodilator reserve in hibernating myocardium before and after coronary. Characterization of hibernating and stunned myocardium. In contrast, hibernation is an important complication of myocardial ischemia. Myocardial stunning with partial aneurysmal formation generated during the recovering process of tachycardiainduced cardiomyopathy. Myocardial stunning refers to transient postischemic contractile abnormalities seen after reperfusion has been restored. These modalities can be used to distinguish between. Cardioprotection in stunned and hibernating myocardium. Myocardial stunning, hibernation and preconditioning. Stunning a lesssevere form of dysfunction and, consequently, more likely to recover function following revascularization. Myocardial stunning represents the myocardial dysfunction that follows a brief ischemic event. Hibernating myocardium an overview sciencedirect topics. Pdf delineation of myocardial stunning and hibernation.
Hibernating myocardium radiology reference article. Enddiastolic wall thickness as a predictor of recovery of function in myocardial hibernation. In contrast, hibernating myocardium refers to dysfunction of viable tissue as a result of prolonged. Houston methodist debakey cv education 2,841 views 58. Assessment of myocardial viability with dobutamine stress. It is now widely believed that repetitive episodes of stunning i. Shivalkar b, flameng w, szilard m, pislaru s, borgers m, vanhaecke j. Thus stunning and hibernation are likely to be part of a continuous disease spectrum 16.
Myocardial hibernation represents a state of persistent regional contractile ventricular. Evaluating myocardial viability role of multimodality imaging, january 24, 2017 duration. Myocardium that is not functioning may be dead infarct or scar, viable but stunned postischemic ventricular dysfunction, viable but hibernating chronic low flow state, or acutely ischemic. It may be short term, in which case no ultrastructural changes occur, or long term when myofibrils are disorganised and reduced in number, and myocardial glucose content and extracellular collagen are increased. Demonstration of intermittent ischemia and stunning in. The concepts of stunned and hibernating myocardium were described and. Both stunned and hibernating myocardium can retain their inotropic capacity with reperfusion.
Myocardial stunning definition of myocardial stunning by. Pdf current interpretation of myocardial stunning researchgate. Stunning, hibernation, and assessment of myocardial. The hypothesis that stunning is due to altered calcium flux, that is, calcium entry after reperfusion, is supported by the observation that nifedipine given 30 minutes after reperfusion restores myocardial function toward normal. Revascularization of severe hibernating myocardium in the. Stunned myocardium has clearly been documented a in experimental studies of brief coronary artery occlusion followed by reperfusion, and b in myocardial infarct models in which early reperfusion. Myocardial stunning, hibernation, and ischemic preconditioning myocardial stunning, hibernation, and ischemic preconditioning vroom, margreeth b van wezel, harry b. Excellent animal models for myocardial stunning exist and the human corollar. Stunning, hibernation, and assessment of myocardial viability. The duration of reduced performance myocardial stunning, depends on the duration of the preceding ischemia. Transgenic system for conditional induction and rescue of chronic myocardial hibernation provides insights into genomic programs of hibernation. Acute myocardial ischemia rapidly impairs contractile function.
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