Implications for coronary heart disease and hibernation. Acute, coronary occlusion causes a rapid decline within seconds in ventricular performance. In ischemic heart disease, evaluating myocardial viability is important because hibernating myocardium can recover function after. 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. The deleterious effects of repetitive myocardial stunning have also been proposed as the potential underlying cause for the higher mortality in patients with high. Stunning, hibernation, and assessment of myocardial viability. Strategies to assess and prevent myocardial stunning have not been standardized. The observation that marked reduction of free radical generation and.
Myocardial hibernation article about myocardial hibernation. Hibernating myocardium synonyms, hibernating myocardium pronunciation, hibernating myocardium translation, english dictionary definition of hibernating myocardium. Oxygenderived free radicals and postischemic dysfunction stunned. A wall motion abnormality at rest which improves during a low. Ultrastructural studies of myocardial hibernation have been performed on biopsies from hearts of patients with regional wall motion abnormalities undergoing surgical revascularization.
Thus stunning and hibernation are likely to be part of a continuous disease spectrum 16. Myocardial stunning cardiovascular research oxford. As a result, stunned myocardium uses oxygen and substrates only inefficiently, leading to poor functional recovery. Myocardial stunning or hibernating myocardium youtube. A term of art for prolonged, nonpermanent, postischaemic, systolic and or diastolic ventricular dysfunction without myocardial necrosis. Hibernating myocardium must be distinguished from the stunned. However, the statement pertaining to postinfarction cardiogenic shock that acute revascularization should result in immediate improvement in the function of the ischemic areas and of. Stunning, hibernation, and calcium in myocardial ischemia and reperfusion pp. Myocardial stunning, as it almost regularly occurs in cardiac surgery, precipitates changes in the aerobic metabolism of glucose, fatty acids, and lactate. In cardiology, hibernating myocardium is a state when some segments of the myocardium exhibit abnormalities of contractile function. Characterization of hibernating and stunned myocardium. Less than 20 years ago, contractile dysfunction of the myocardium in patients with coronaryartery narrowing was thought to be caused by either irreversible damage to myocytes that is, myocardial. Inotropic responses to postextrasystolic potentiation and intracoronary calcium.
Myocardial stunning, hibernation, and ischemic preconditioning myocardial stunning, hibernation, and ischemic preconditioning vroom, margreeth b van wezel, harry b. Stunning, hibernation, and calcium in myocardial ischemia. The observation that marked reduction of free radical generation and contractile function by antioxidant therapy began at the time of reperfusion supports the concept that myocardial stunning is a manifestation of reperfusion injury. Characterization of hibernating and stunned myocardium oxford.
Hibernation cardiology persistent left ventricular dysfunction when myocardial perfusion is chronically reduced but still enough to maintain tissue viability. Myocardial hibernation definition of myocardial hibernation. Sawyer and md, phd joseph loscalzo md, phdfrom the whitaker cardiovascular institute and evans department of medicine, boston university school of medicine, boston, mass. Read stunning, hibernation, and calcium in myocardial ischemia and reperfusion by available from rakuten kobo. The optimal strategy for risk stratification in heart failure continues to evolve, with increasing numbers of tools such as natriuretic peptide assessment being utilised the assessment of risk, and its subsequent manipulation, accounts for a large amount of what we do in cardiology. Editorial from the new england journal of medicine hibernation and stunning of the myocardium. After placing a left atrial cannula, the coronary vessels were dissected free in the proximal portion and ameroid occluders dimed medical engineering, antwerp, belgium were placed around the left circumflex and right coronary artery.
At approximately 30 minutes after the onset of total ischemia the damage becomes irreversible, thereby ending the phase of myocardial stunning. Myocardial contrast echocardiography mce intracoronary contrast administration has emerged as a modality for assessing myocardial perfusion, and it has the potential to predict myocardial viability. Hibernating myocardium radiology reference article. A term of art for prolonged, nonpermanent, postischaemic, systolic andor diastolic ventricular dysfunction without myocardial necrosis. These conditions result from a switch in gene and protein expression, which sustains cardiac cell survival in a context of oxygen deprivation and during the stress of reperfusion. The term hibernating myocardium was coined to describe a state of persistently impaired left ventricular function due to a reduced coronary blood flow but distinct from acute myocardial stunning, which will be partially or completely restored following revascularization. Whereas myocardial hibernation was originally seen as a chronic. Pathophysiology of stunned or hibernating myocardium uptodate. Myocardial stunning and hibernation statpearls ncbi bookshelf.
Among the heart failure population, increasing numbers of tools are being utilised for the purpose. Repeated stunning precedes myocardial hibernation in progressive multiple coronary artery obstruction. Hibernating myocardium an overview sciencedirect topics. Cellular calcium overload and the generation of oxygen free radicals most probably play the major role in the pathogenesis of myocardial stunning.
Stunning, hibernation, and calcium in myocardial ischemia and. Studied interventions have included employing cooled dialysate, lowered ultrafiltration rates, and more frequent dialysis. Myocardial stunning or hibernating myocardium latisom. These molecular mechanisms result in physiological conditions of adaptation to ischemia, known as myocardial stunning and hibernation. It is common in patients with ischemic cardiomyopathy, 26 where it frequently coexists with nontransmural infarction and can also occur in the absence of heart failure or global lv dysfunction. Brief ischemic episodes 30 minutes followed by reperfusion can produce myocardial stunning, and full recovery is usually over hours to days. As a result, stunned myocardium uses oxygen and substrates only.
Severe energy deprivation of human hibernating myocardium. Repeated stunning precedes myocardial hibernation in. Clonidine, an alpha 2adrenergic agonist, has been widely used in anesthesia because of its sedative, analgesic, sympatholytic, and specific hemodynamic effects. Myocardial hibernation is a term used to describe the condition in which regional cardiac function is depressed due to chronic ischemia. In myocardial stunning ms, the myocardium is viable and has contractile reserve. Choice b myocardial stunning is a less severe form of ischemiainduced reversible loss of contractile function than hibernation. Myocardial stunning definition of myocardial stunning by. 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. Repetitive myocardial stunning may also predispose to development of permanent segmental abnormalities. If coronary flow is reestablished, ventricular function will slowly return to normal. Hibernating myocardium is myocardial tissue that has reduced contractility due to poor perfusion but remains viable. Pdf myocardial stunning is a temporary postischemic cardiac. However, this theory has not yet been confirmed by animal and human experiments.
Imaging modalities have become frontline methods in the assessment of viable myocardial tissue, with the aim to stratify patients into optimal treatment pathways. The pivotal importance of myocardial perfusion for the maintenance of myocardial contractile function was already recognized some 60 years ago, but the functional and metabolic consequences of brief as well as long coronary artery occlusions have become unravelled only in the last twenty years. However, the statement pertaining to postinfarction cardiogenic shock that acute revascularization. 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. In contrast, hibernation is an important complication of myocardial ischemia. If you are experiencing a medical emergency, please call your doctor immediately or dial 911 from your phone. Therefore, these focussed issues are now combined and published as a separate monograph. The pattern of cell survival elicited by ischemia in myocardial stunning or hibernation results in the activation of cytoprotective mechanisms that will protect the heart against further ischemic damage, a condition referred to as ischemic preconditioning. Stunned vs hibernating myocardium jama jama network. Stunning, hibernation, and assessment of myocardial. This is unfortunate because the differences between these two pathophysiologies, or more importantly how they typically present, are key to interpreting the literature. Treatment of hibernating myocardial is to reperfuse the hypoperfused myocardium with blood.
Hibernation currently is viewed not as a simple consequence of an oxygen deficit, but as an adaptive response to maintain cardiomyocyte viability in the setting of reduced blood flow. Decreased myocardial contraction occurs as a consequence of a reduction in blood flow. Pet scanning, dobutamine echocardiography, and thallium redistribution studies are used to attempt to identify viable, but hibernating, myocardium. 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. This definition implies that myocardial hibernation is defined solely by the clinical time course and not as a. Subsequent to this is a period of myocardial stunning, in which reversible ischemic damage is taking place. Seven dogs were chronically instrumented to allow measurement of left atrial pressure lap, aortic blood pressure abp, left ventricular pressure lvp, maximal rate of increase of lvp lvdpdt max, and myocardial wall thickening fraction wtf. 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.
Some authors have suggested that stunning, silent ischemia, and hibernating myocardium are processes by which the myocardium adapts to reduced myocardial oxygen supply to maintain cellular integrity. It is now widely believed that repetitive episodes of stunning i. Stunned myocardium is defined as viable myocardium that exhibits prolonged postischemic dysfunction. Stunning is found following coronary angioplasty, thrombolysis, coronary vasospasm, and cardiopulmonary bypass. Acute myocardial ischemia rapidly impairs contractile function. Jun 29, 2018 myocardial ischemia is a clinical syndrome manifesting a variety of tissue effects and global cardiac effects that impair cardiac function.
The use of clonidine in myocardial ischemia is controversial because of its bradycardic and hypotensive effects. Initial studies, although favorable, lacked sufficient power and sample size to provide conclusive outcomes of viability. When ischemia is severe and prolonged, it causes myocyte death and results in loss of contractile function and tissue infarction. Myocardial stunning is the reversible reduction of function of heart contraction after reperfusion not accounted for by tissue damage or reduced blood flow.
There are 2 major hypothesis for myocardial stunning. Myocardial contrast enhancement depends on an intact microcirculation. Stunning is potentially an important complication of myocardial reperfusion. The original definition did not specify whether there was an abnormality in resting myocardial blood flow. Calcium responsiveness in regional myocardial shortterm hibernation and stunning in the in situ porcine heart. Delineation of myocardial stunning and hibernation. Hibernation defines one form of pathophysiological response to myocardial ischemia, the other two being stunning and. The definitions and pathophysiology of myocardial stunning and hibernation will be. Pdf current interpretation of myocardial stunning researchgate. Over the last year, focussed issues on myocardial hibernation, myocardial stunning and ischemic preconditioning were published in basic research in car diology. Cardioprotection in stunned and hibernating myocardium. 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. Stunning a lesssevere form of dysfunction and, consequently, more likely to recover function following revascularization.
Hibernating myocardium is characterized by contractile dysfunction with reduced resting flow, in the absence of acute ischemia or significant necrosis. Myocardial stunning refers to transient postischemic contractile abnormalities seen after reperfusion has been restored. Myocardial stunning cardiovascular research oxford academic. May 05, 2014 it is now widely believed that repetitive episodes of stunning i. Clonidine improves recovery from myocardial stunning in. Myocardial stunning and hibernation statpearls ncbi. Myocardial stunning and hibernation appear to be part of the same.
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 contrast, the patient in the vignette appears to have had a chronic. These abnormalities can be visualised with echocardiography, cardiac magnetic resonance imaging cmr, nuclear medicine pet or ventriculography. Ms may follow successful thrombolytic therapy in evolving acute mi, percutaneous transluminal. Strictly speaking, hibernation is the dormant state undergone in response to cold by certain mammals. In their article, schinkel and colleagues 1 avoid the use of the terms hibernation and stunning, perhaps because of controversy over what these entities actually represent. Ischaemic left ventricular lv dysfunction can arise from myocardial stunning, hibernation, or necrosis. In the present study, we tested the hypothesis that clonidine improves recovery from myocardial stunning in conscious dogs. The duration of reduced performance myocardial stunning, depends on the duration of the preceding ischemia.
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