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| __NOTOC__ | | __NOTOC__ |
| | {{Reperfusion injury}} |
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| {{SI}} | | {{CMG}} {{AE}} {{AC}} {{Shivam Singla}} |
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| {{CMG}} | | {{SK}} Reperfusion Damage; Damage, Reperfusion; Damages, Reperfusion; Reperfusion Damages; Ischemia-Reperfusion Injury; Ischemia-Reperfusion Injury; Injury, Ischemia-Reperfusion; Injuries, Ischemia-Reperfusion; Injury, Ischemia-Reperfusion; Ischemia-Reperfusion Injuries; Injury, Reperfusion; Injuries, Reperfusion; Reperfusion Injuries |
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| ==Overview== | | ==[[Reperfusion injury overview|Overview]]== |
| '''Reperfusion injury''' refers to damage to [[tissue (biology)|tissue]] caused when [[blood]] supply returns to the tissue after a period of [[ischemia]]. The absence of [[oxygen]] and [[nutrient]]s from blood creates a condition in which the restoration of [[circulatory system|circulation]] results in [[inflammation]] and [[oxidation|oxidative]] damage through the induction of [[oxidative stress]] rather than restoration of normal function.
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| ==Mechanisms of reperfusion injury== | | ==[[Reperfusion injury pathophysiology|Pathophysiology]]== |
| The damage of reperfusion injury is due in part to the [[inflammatory response]] of damaged tissues. [[White blood cell]]s carried to the area by the newly returning blood release a host of [[cytokine|inflammatory factors]] such as [[interleukin]]s as well as [[reactive oxygen species|free radicals]] in response to tissue damage
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| <ref name="WMClark">{{cite web | last = Clark | first = Wayne M. | title = Reperfusion Injury in Stroke | work = eMedicine | publisher = WebMD | date = January 5, 2005 | url = http://www.emedicine.com/neuro/topic602.htm | accessdate = 2006-08-09 }}</ref>.The restored blood flow reintroduces oxygen within [[cell (biology)|cell]]s that damages cellular [[protein]]s, [[DNA]], and the [[plasma membrane]]. Damage to the cell's membrane may in turn cause the release of more free radicals. Such reactive species may also act indirectly in [[redox signaling]] to turn on [[apoptosis]]. Leukocytes may also build up in small [[capillary|capillaries]], obstructing them and leading to more ischemia<ref name="WMClark" />. Other pathophysiologic disturbances include intracellular calcium overload and the opening of mitochondrial permeability transition pores. <ref name="pmid14962470">{{cite journal |author=Halestrap AP, Clarke SJ, Javadov SA |title=Mitochondrial permeability transition pore opening during myocardial reperfusion--a target for cardioprotection |journal=Cardiovasc. Res. |volume=61 |issue=3 |pages=372–85 |year=2004 |month=February |pmid=14962470 |doi=10.1016/S0008-6363(03)00533-9 |url=http://cardiovascres.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=14962470}}</ref>
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| In prolonged ischemia (60 minutes or more), [[hypoxanthine]] is formed as breakdown product of [[Adenosine triphosphate|ATP]] metabolism. The enzyme ''[[xanthine dehydrogenase]]'' is converted to ''[[xanthine oxidase]]'' as a result of the higher availability of oxygen. This oxidation results in molecular oxygen being converted into highly reactive [[superoxide]] and [[hydroxyl]] [[Radical (chemistry)|radicals]]. Xanthine oxidase also produces [[uric acid]], which may act as both a prooxidant and as a scavenger of reactive species such as peroxinitrite. Excessive [[nitric oxide]] produced during reperfusion reacts with [[superoxide]] to produce the potent reactive species [[peroxynitrite]]. Such radicals and reactive oxygen species attack cell membrane lipids, proteins, and glycosaminoglycans, causing further damage. They may also initiate specific biological processes by [[redox signaling]].
| | ==[[Reperfusion injury risk factors|Risk Factors]]== |
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| ==Specific organs affected by reperfusion injury== | | ==[[Reperfusion injury natural history|Natural History, Complications & Prognosis]]== |
| ===The central nervous system===
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| Reperfusion injury plays a part in the [[brain]]'s [[ischemic cascade]], which is involved in [[stroke]] and [[brain trauma]]. Repeated bouts of ischemia and reperfusion injury also are thought to be a factor leading to the formation and failure to [[wound healing|heal]] of [[chronic wound]]s such as [[pressure sore]]s and [[diabetic foot]] [[ulcer]]s<ref name="TMustoe">{{cite journal | author=Mustoe T. | title=Understanding chronic wounds: a unifying hypothesis on their pathogenesis and implications for therapy | journal=AMERICAN JOURNAL OF SURGERY | volume=187 | issue=5A | year=2004 | pages=65S-70S | id=PMID 15147994}}</ref>. Continuous pressure limits blood supply and causes ischemia, and the inflammation occurs during reperfusion. As this process is repeated, it eventually damages tissue enough to cause a [[wound]]<ref name="TMustoe" />.
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| ===The myocardium=== | | ==Treatment== |
| Restoration of epicardial patency can be associated with reperfusion injury in the myocardium. While many pharmacotherapies are successful in limiting reperfusion injury in animal studies or ex-vivo, many have failed to improve clinical outcomes in randomized clinical trials in patients. Pharmacotherapies that have either failed or that have met with limited success in improving clinical outcomes include: <ref name="pmid17306241">{{cite journal |author=Dirksen MT, Laarman GJ, Simoons ML, Duncker DJ |title=Reperfusion injury in humans: a review of clinical trials on reperfusion injury inhibitory strategies |journal=Cardiovasc. Res. |volume=74 |issue=3 |pages=343–55 |year=2007 |month=June |pmid=17306241 |doi=10.1016/j.cardiores.2007.01.014 |url=http://cardiovascres.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=17306241}}</ref>
| | '''[[Reperfusion injury medical therapy|Medical Therapy]]''' |
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| #[[Beta-blockade]]
| | '''[[Reperfusion injury future or investigational therapies|Future or Investigational Therapies]]''' |
| #GIK (glucose-insulin-potassium infusion) (Studied in the Glucose-Insulin-Potassium Infusion in Patients With Acute Myocardial Infarction Without Signs of Heart Failure: The Glucose-Insulin-Potassium Study (GIPS)-II <ref name="pmid16631017">{{cite journal |author=Timmer JR, Svilaas T, Ottervanger JP, ''et al'' |title=Glucose-insulin-potassium infusion in patients with acute myocardial infarction without signs of heart failure: the Glucose-Insulin-Potassium Study (GIPS)-II |journal=J. Am. Coll. Cardiol. |volume=47 |issue=8 |pages=1730–1 |year=2006 |month=April |pmid=16631017 |doi=10.1016/j.jacc.2006.01.040 |url=http://linkinghub.elsevier.com/retrieve/pii/S0735-1097(06)00178-1}}</ref>
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| #Sodium-hydrogen exchange inhibitors such as cariporide (Studied in the GUARDIAN <ref name="pmid11120691">{{cite journal |author=Théroux P, Chaitman BR, Danchin N, ''et al'' |title=Inhibition of the sodium-hydrogen exchanger with cariporide to prevent myocardial infarction in high-risk ischemic situations. Main results of the GUARDIAN trial. Guard during ischemia against necrosis (GUARDIAN) Investigators |journal=Circulation |volume=102 |issue=25 |pages=3032–8 |year=2000 |month=December |pmid=11120691 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=11120691}}</ref> <ref name="pmid11714411">{{cite journal |author=Theroux P, Chaitman BR, Erhardt L, ''et al'' |title=Design of a trial evaluating myocardial cell protection with cariporide, an inhibitor of the transmembrane sodium-hydrogen exchanger: the Guard During Ischemia Against Necrosis (GUARDIAN) trial |journal=Curr Control Trials Cardiovasc Med |volume=1 |issue=1 |pages=59–67 |year=2000 |pmid=11714411 |pmc=56207 |doi= |url=http://cvm.controlled-trials.com/content/1/1/59}}</ref> and EXPIDITION <ref name="pmid12691376">{{cite journal |author=Bolli R |title=The role of sodium-hydrogen ion exchange in patients undergoing coronary artery bypass grafting |journal=J Card Surg |volume=18 Suppl 1 |issue= |pages=21–6 |year=2003 |pmid=12691376 |doi= |url=http://www3.interscience.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0886-0440&date=2003&volume=18&issue=&spage=21}}</ref> <ref name="pmid18355507">{{cite journal |author=Mentzer RM, Bartels C, Bolli R, ''et al'' |title=Sodium-hydrogen exchange inhibition by cariporide to reduce the risk of ischemic cardiac events in patients undergoing coronary artery bypass grafting: results of the EXPEDITION study |journal=Ann. Thorac. Surg. |volume=85 |issue=4 |pages=1261–70 |year=2008 |month=April |pmid=18355507 |doi=10.1016/j.athoracsur.2007.10.054 |url=http://linkinghub.elsevier.com/retrieve/pii/S0003-4975(07)02183-2}}</ref> trials)
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| #[[Adenosine]] (Studied in the AMISTAD I <ref name="pmid10577561">{{cite journal |author=Mahaffey KW, Puma JA, Barbagelata NA, ''et al'' |title=Adenosine as an adjunct to thrombolytic therapy for acute myocardial infarction: results of a multicenter, randomized, placebo-controlled trial: the Acute Myocardial Infarction STudy of ADenosine (AMISTAD) trial |journal=J. Am. Coll. Cardiol. |volume=34 |issue=6 |pages=1711–20 |year=1999 |month=November |pmid=10577561 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0735109799004180}}</ref> and AMISTAD II <ref name="pmid15936605">{{cite journal |author=Ross AM, Gibbons RJ, Stone GW, Kloner RA, Alexander RW |title=A randomized, double-blinded, placebo-controlled multicenter trial of adenosine as an adjunct to reperfusion in the treatment of acute myocardial infarction (AMISTAD-II) |journal=J. Am. Coll. Cardiol. |volume=45 |issue=11 |pages=1775–80 |year=2005 |month=June |pmid=15936605 |doi=10.1016/j.jacc.2005.02.061 |url=http://linkinghub.elsevier.com/retrieve/pii/S0735-1097(05)00536-X}}</ref> trials as well as the ATTACC trial <ref name="pmid12743668">{{cite journal |author=Quintana M, Hjemdahl P, Sollevi A, ''et al'' |title=Left ventricular function and cardiovascular events following adjuvant therapy with adenosine in acute myocardial infarction treated with thrombolysis, results of the ATTenuation by Adenosine of Cardiac Complications (ATTACC) study |journal=Eur. J. Clin. Pharmacol. |volume=59 |issue=1 |pages=1–9 |year=2003 |month=May |pmid=12743668 |doi=10.1007/s00228-003-0564-8 |url=http://dx.doi.org/10.1007/s00228-003-0564-8}}</ref>). It should be noted that at high doses in anterior ST elevation MIs, adenosine was effective in the AMISTAD trial. Likewise, intracoronary administration of adenosine prior to primary PCI has been associated with imporved ehcocardiographic and clinical outcomes in one small study. <ref name="pmid10801755">{{cite journal |author=Marzilli M, Orsini E, Marraccini P, Testa R |title=Beneficial effects of intracoronary adenosine as an adjunct to primary angioplasty in acute myocardial infarction |journal=Circulation |volume=101 |issue=18 |pages=2154–9 |year=2000 |month=May |pmid=10801755 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=10801755}}</ref>
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| #[[Calcium-channel blockers]]
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| #Potassium–adenosine triphosphate channel openers
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| #Antibodies directed against leukocyte adhesion molecules such as CD 18 (Studied in the LIMIT AMI trial <ref name="pmid11733394">{{cite journal |author=Baran KW, Nguyen M, McKendall GR, ''et al'' |title=Double-blind, randomized trial of an anti-CD18 antibody in conjunction with recombinant tissue plasminogen activator for acute myocardial infarction: limitation of myocardial infarction following thrombolysis in acute myocardial infarction (LIMIT AMI) study |journal=Circulation |volume=104 |issue=23 |pages=2778–83 |year=2001 |month=December |pmid=11733394 |doi= |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=11733394}}</ref>)
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| #Oxygen free radical scavengers
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| #Pexelizumab, a humanized monoclonal antibody that binds the C5 component of complement (Studied in the Pexelizumab for Acute ST-Elevation Myocardial Infarction in Patients Undergoing Primary Percutaneous Coronary Intervention (APEX AMI) trial <ref name="pmid17200474">{{cite journal |author=Armstrong PW, Granger CB, Adams PX, ''et al'' |title=Pexelizumab for acute ST-elevation myocardial infarction in patients undergoing primary percutaneous coronary intervention: a randomized controlled trial |journal=JAMA |volume=297 |issue=1 |pages=43–51 |year=2007 |month=January |pmid=17200474 |doi=10.1001/jama.297.1.43 |url=http://jama.ama-assn.org/cgi/pmidlookup?view=long&pmid=17200474}}</ref> )
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| # KAI-9803, a delta-protein kinase C inhibitor (Studied in the Intracoronary KAI-9803 as an adjunct to primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction trial or DELTA AMI trial)<ref name="pmid18250271">{{cite journal |author=Bates E, Bode C, Costa M, ''et al'' |title=Intracoronary KAI-9803 as an adjunct to primary percutaneous coronary intervention for acute ST-segment elevation myocardial infarction |journal=Circulation |volume=117 |issue=7 |pages=886–96 |year=2008 |month=February |pmid=18250271 |doi=10.1161/CIRCULATIONAHA.107.759167 |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=18250271}}</ref>.
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| #Human atrial natriuretic peptide (Studied in the Human atrial natriuretic peptide and nicorandil as adjuncts to reperfusion treatment for acute myocardial infarction (J-WIND): two randomised trials.)<ref name="pmid17964349">{{cite journal |author=Kitakaze M, Asakura M, Kim J, ''et al'' |title=Human atrial natriuretic peptide and nicorandil as adjuncts to reperfusion treatment for acute myocardial infarction (J-WIND): two randomised trials |journal=Lancet |volume=370 |issue=9597 |pages=1483–93 |year=2007 |month=October |pmid=17964349 |doi=10.1016/S0140-6736(07)61634-1 |url=http://linkinghub.elsevier.com/retrieve/pii/S0140-6736(07)61634-1}}</ref>
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| Therapies that have been associated with improved clinical outcomes include
| | ==Related Chapters== |
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| #Post conditioning (short repeated periods of vessel opening by repeatedly blowing the balloon up for short periods of time).<ref name="pmid18268150">{{cite journal |author=Thibault H, Piot C, Staat P, ''et al'' |title=Long-term benefit of postconditioning |journal=Circulation |volume=117 |issue=8 |pages=1037–44 |year=2008 |month=February |pmid=18268150 |doi=10.1161/CIRCULATIONAHA.107.729780 |url=http://circ.ahajournals.org/cgi/pmidlookup?view=long&pmid=18268150}}</ref>
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| #Inhibition of mitochondrial pore opening by cyclosporine
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| ==See also==
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| * [[Ischemia]] | | * [[Ischemia]] |
| * [[Myocardial_infarction#Reperfusion|Myocardial infarction -- Reperfusion]] | | * [[Myocardial_infarction#Reperfusion|Myocardial infarction -- Reperfusion]] |
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| ==References==
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| {{reflist|2}}
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| ==External links==
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| * [http://www.benbest.com/cryonics/ischemia.html#reperfuse Reperfusion Injury and "No Reflow"]
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| * [http://www.newsweek.com/id/35045 Docs Change the Way They Think About Death]
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| [[Category:Physiology]] | | [[Category:Physiology]] |
| [[Category:Neurotrauma]] | | [[Category:Neurotrauma]] |
| | [[Category:Cardiology]] |
| | [[Category:Up-To-Date]] |
| | [[Category:Up-To-Date cardiology]] |