Myocardial stunning, as it almost regularly occurs in cardiac surgery, precipitates changes in the aerobic metabolism of glucose, fatty acids, and lactate. If you cant understand it, just dont worry about it, you dont have to understand it. If, however, myocardial stunning is severe, involves large parts of the left ventricle. Stunning is found following coronary angioplasty, thrombolysis, coronary vasospasm, and cardiopulmonary bypass. Myocardial stunning definition of myocardial stunning by. That would be the explanation regarding the difference between stunned myocardium and hibernating myocardium. Coincident with the exploration of stunning and hibernation was the discovery of ischaemic preconditioning. Read delineation of myocardial stunning and hibernation by positron emission tomography in advanced coronary artery disease, american heart journal on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available. New paradigms of coronary artery disease hibernation.
Characterization of hibernating and stunned myocardium oxford. Both stunned and hibernating myocardium can retain their inotropic capacity with reperfusion. 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. Read stunning, hibernation, and calcium in myocardial ischemia and reperfusion by available from rakuten kobo. Myocardial stunning or hibernating myocardium youtube. C, hibernation in a patient with severe fixed coronary stenosis.
Selected references these references are in pubmed. 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 this situation, while myocardial blood flow mbf returns to normal, function is still depressed for a variable period of time. Sawyer and md, phd joseph loscalzo md, phdfrom the whitaker cardiovascular institute and evans department of medicine, boston university school of medicine, boston, mass.
This was originally defined as a brief period of ischaemia protecting the myocardium from a subsequent more prolonged period of ischaemia. The difference between stunned myocardium and hibernating. Delineation of myocardial stunning and hibernation by. Inotropic responses to postextrasystolic potentiation and intracoronary calcium. Choice b myocardial stunning is a less severe form of ischemiainduced reversible loss of contractile function than hibernation.
Assessment of myocardial viability with dobutamine stress. Hibernating myocardium an overview sciencedirect topics. Stunning is potentially an important complication of myocardial reperfusion. Initially, the concept of myocardial hibernation was characterizes their essential features separately. Answer hibernating myocardium is heart muscle that does not pump normally because of decreased blood flow, usually from a coronary artery blockage. In this case, each episode is followed by a brief period of stunning flowfunction mismatch. Hibernation is the concomitant reduction of myocardial flow and contractility, whereas stunning is contractile impairment persisting for some time after perfusion. Core topics in cardiac anesthesia, edited by jonathan h mackay and joseph e arrowsmith, 2nd ed. While the smart heart theory postulates that reduced myocardial blood flow mbf at rest is responsible for myocytes switching to a state of hibernation, other theories suggest that a reduced myocardial flow. Usmle step 1 questions at life and times in schools of medicine inc. Decreased myocardial contraction occurs as a consequence of a reduction in blood flow. A wall motion abnormality at rest which improves during a. Pdf delineation of myocardial stunning and hibernation.
Myocardial stunning an overview sciencedirect topics. Resting myocardial blood flow is impaired in hibernating myocardium. The human pathophysiology of stunned, hibernating and scarred myocardium in ischemic cardiomyopathy is a subject of controversy. Stunning, hibernation, and assessment of myocardial viability. Myocardial stunning and hibernation in clinical practice. Myocardial ischaemia, reperfusion, hiber nation, stunning. There is some evidence that both myocardial stunning and hibernation can coexist, and some authors even favor the concept that myocardial hibernation is caused by repeated episodes of stunning. This results in the electromechanical uncoupling of energy generation from contraction that characterizes myocardial stunning. Hibernation cardiology persistent left ventricular dysfunction when myocardial perfusion is chronically reduced but still enough to maintain tissue viability.
Myocardial stunning, defined here as transient development of segmental wall motion abnormalities with ventricular dysfunction, has been estimated to occur in 27% to 64% of patients during dialysis. 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. The therapy of hibernating myocardium is to restore blood flow to the hypoperfused tissue. Stunning, hibernation, and calcium in myocardial ischemia. In cardiology, hibernating myocardium is a state when some segments of the myocardium exhibit abnormalities of contractile function. When ischemia is severe and prolonged, it causes myocyte death and results in loss of contractile function and tissue infarction. Myocardial stunning, hibernation and preconditioning.
A term of art for prolonged, nonpermanent, postischaemic, systolic andor diastolic ventricular dysfunction without myocardial necrosis. Hibernation defines one form of pathophysiological response to myocardial ischemia, the other two being stunning and. Repeated stunning precedes myocardial hibernation in. A, brief episode of ischemia caused by thrombosis andor vasoconstriction. Myocardial stunning tends to occur following an episode of acute coronary occlusion followed by rapid resumption of normal coronary and myocardial blood flow as in patients. Latisom offers a video streaming question bank for usmle step 1 a. In myocardial stunning ms, the myocardium is viable and has contractile reserve.
In both stunning and hibernation, the basic pathology is a hypoperfused myocardium. Characterization of hibernating and stunned myocardium. The full text of this article is available as a pdf 7k. Myocardial stunning and hibernation statpearls ncbi. Request pdf myocardial stunning and hibernation in clinical practice myocardial stunning and hibernation are both clinically important causes of myocardial dysfunction and are caused by. This book presents different viewpoints on these subjects, taken from a series of peer. These two conditions are very similar to each other so theres no need for you to bother to know the difference between them.
Stunned myocardium refers to a situation in which an acute transient myocardial ischemic event results in a prolonged wall motion abnormality which eventually resolves the term is usually distinguished from hibernating myocardium, in which a chronic ischemic process leads to chronic left ventricular dysfunction. However, the statement pertaining to postinfarction cardiogenic shock that acute revascularization should result in immediate improvement in the function of the. Hibernating myocardium represents a chronic myocardial dysfunction at rest associated with reduced coronary perfusion. Bigger jt, jr, fleiss jl, kleiger r, miller jp, rolnitzky lm. Reperfusion of shortterm hibernation also leads to stunning, which. Pdf stunning, hibernation, and assessment of myocardial. Stunned vs hibernating myocardium jama jama network. When a severe reduction of coronary blood flow persists for more than. Acute myocardial ischemia rapidly impairs contractile function. Editorial from the new england journal of medicine hibernation and stunning of the myocardium. Myocardial ischemia is a clinical syndrome manifesting a variety of tissue effects and global cardiac effects that impair cardiac function. The original definition did not specify whether there was an abnormality in resting myocardial blood flow. Upon reperfusion, regional function can remain depressed as a result of myocardial stunning vide infra.
Enddiastolic wall thickness as a predictor of recovery of function in myocardial hibernation. Stunning, hibernation, and assessment of myocardial. Ultrastructural studies of myocardial hibernation have been performed on biopsies from hearts of patients with regional wall motion abnormalities undergoing surgical revascularization. There probably is no single mechanism that results in myocardial stunning but several should be considered.
The difficulty in developing chronic experimental models of coronary artery stenosis has hampered our detailed understanding of the multiple. Myocardial stunning and hibernation statpearls ncbi bookshelf. However, the clini distinction between shortterm hibernation and chronic cal concept of hibernation quickly merged with a num hibernation is certainly arbitrary in the sense that it uses. This may not be the complete list of references from this article. Myocardial stunning refers to transient postischemic contractile abnormalities seen after reperfusion has been restored. Although myocardial contraction is depressed, metabolic balance is maintained, myocytes remain viable and myocardial contraction can be restored with myocardial revascularization. Myocardial stunning is the reversible reduction of function of heart contraction after reperfusion not accounted for by tissue damage or reduced blood flow. Pet scanning, dobutamine echocardiography, and thallium redistribution studies are used to attempt to identify viable, but hibernating, myocardium. Brief ischemic episodes 30 minutes followed by reperfusion can produce myocardial stunning, and full recovery is usually over hours to days. Calcium responsiveness in regional myocardial shortterm hibernation and stunning in the in situ porcine heart.
Read myocardial stunning, hibernation, and ischemic preconditioning, journal of cardiothoracic and vascular anesthesia on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. 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. 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. 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. In contrast, hibernation is an important complication of myocardial ischemia. Stunned myocardium is defined as viable myocardium that exhibits. Specifically, two phenomena may account for this contractile dysfunction of viable myocytes. These abnormalities can be visualised with echocardiography, cardiac magnetic resonance imaging cmr, nuclear medicine pet or ventriculography. In contrast, the patient in the vignette appears to have had a chronic.
Delineation of myocardial stunning and hibernation by positron emission tomography in advanced coronary artery disease. For many years, the functional sequelae of chronic coronary artery disease were considered irreversible and amenable only to palliative therapy. No differences in rest myocardial blood flow in stunned. The elusive difference between hibernation and stunning in patients. 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 viability are discussed elsewhere. B, episode of silent ischemia caused by recurrent thrombosis andor vasoconstriction. Therefore, these focussed issues are now combined and published as a separate monograph. As a result, stunned myocardium uses oxygen and substrates only inefficiently, leading to poor functional recovery. Chapter 36 pathophysiologic basis of hibernating myocardium. For full access to this pdf, sign in to an existing account, or. Pathophysiology of stunned or hibernating myocardium uptodate. 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. Myocardial hibernation is a term used to describe the condition in which regional cardiac function is depressed due to chronic ischemia.
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