Oxygen therapy reduces secondary hemorrhage after thrombolysis in thromboembolic cerebral ischemia

1. Oxygen therapy reduces secondary hemorrhage after thrombolysis in thromboembolic cerebral ischemia Li Sun, Wei Zhou, Christian Mueller, Clemens Sommer, Sabine Heiland, Alexander T Bauer, Hugo H Marti and Roland Veltkamp Journal of Cerebral Blood Flow & Metabolism 30, 1651–1660, 2010 Impact factor：5.478 指導老師：林宏榮 鄭伯智 老師 學生：黃鈴詒

2. Introduction

3. Stroke Stroke is a brain injury. It occurs when the brain's blood supply is interrupted. Without oxygen and nutrients from blood, brain tissue dies quickly (less than 10 minutes). This causes a sudden function loss.

4. Hemorrhagic Stroke Ischemic Stroke Hemorrhage/ blood leaks into brain tissue Clot stops blood supply to an area of the brain Hemorrhagic stroke V.S. Ischemic stroke

5. Chan P.H., 2001

6. The activation and proteolytic activity of matrix metalloproteinases (MMPs), particularly MMP-9, are key factors in the proteolytic disruption of the basal lamina and tight junctions of the BBB. Hawkins and Davis, 2005; Wang et al., 2003.

7. Tissue plasminogen activator (t-PA)should be given within the first 3 hours after the first symptoms of stroke start. Therapy for acute ischemic stroke Therapy for acute ischemic stroke can be approached in two basic ways: • First, by an attempt to restore or improve blood flow in an occluded vascular territory. Second, via therapy directed at the cellular and metabolic targets. Nighoghossian and Trouillas. 1997

8. Tissue plasminogen activator (tPA) (C)Beneficial effects of tPA are successful thrombolysis and restoration of CBF. (D) The deleterious effects come into play through the NMDA receptors, upregulation of MMPs, enhanced accumulation of PMNLs, and free radicals, which results in exacerbation of ischemic injury via excito-neurotoxicity, edema, and hemorrhage. Jaspreet Kaur, et al., 2004

9. HBO • HBO might be more effective in stroke within the first few hours and at a pressure of 2–3 ATA. • HBO is to increase the solubility of oxygen in plasma to a level sufficient to support tissues with minimal extraction of oxygen carried on hemoglobin. Ann K et al. 2005

10. John H. Zhang et al. 2005

11. Hyperbaric oxygen (HBO) and normobaric hyperoxia (NBO) attenuated BBB permeability , edema and do not increase oxidative stress after focal and global ischemia. (Mink and Dutka, 1995; Singhal et al, 2002; Veltkamp et al., 2005a) NBO and HBO attenuates early BBB disruption and inhibition of MMP-9mediated occludin degradation is an important mechanism for this protection. (Liu et al., 2009)

12. AIMS Examine the differences in the effectiveness of oxygen therapy on postischemic BBB damage and secondary hemorrhage after thrombolysis.

13. Materials and Methods

14. Brain Ischemia thrombin-induced thromboemboli (TT-tMCAO) calcium-rich thromboemboli (CT-tMCAO) Mixed with 1.0 National Institutes of Health (NIH) units of human thrombin and 5 μL of 1 mol/L CaCl2 It was allowed to coagulate spontaneously for 2 hours at 37℃. It was exposed to a 20 mmol/L calcium solution for 1 minute. Twelve thrombi —each 0.35mm in diameter and 1.5mm in length Toomey et al ., 2002

15. MRI assay T1W, T2* DWI, PWI Spontaneously hypertensive Rat (300-350g) TT-tMCAO CT-tMCAO 60 minutes 60 minutes air 100% O2 at ambient pressure (NBO) 100% O2 at 3 bar (HBO) 30 minutes rt-PA (9mg/kg) Physiology parameter Histologic staining Hemoglobin Assay Gelatin Zymography MABP,heart rate, blood gas MMP-9 and MMP-2

16. 1. MRI assay PWI document the perfusion status after thrombolysis and at the end of the experiment Lesion volume was quantified in Diffusion-weighted imaging (DWI) brain sections at 2.5 and 24h after tMCAO. Air HBO NBO tMCAO DWI, PWI DWI, PWI rt-PA 2.5 hr 2hr 0hr 1hr 24hr

17. 1. MRI assay Postischemic BBB damage was analyzedon postcontrast T1w images. T2* MR imaging was used to detect ‘macroscopic’ intracerebral hemorrhage. Air HBO NBO tMCAO T1w, T2* T1w, T2* rt-PA 2.5 hr 2hr 0hr 1hr 24hr

18. 2. Spectrophotometric Hemoglobin and Gelatin ZymographyAssay Spectrophotometric assay the hemoglobin content of brains. Gelatin zymography protein expression of MMP-2 and MMP-9 atischemic and nonischemic hemispheres. Air HBO NBO Hemoglobin content tMCAO MMP-2 and MMP-9 rt-PA 2hr 0hr 1hr 24hr

19. 3. Histologic staining- secondary hemorrage • Coronal cryosections the secondary hemorrage of • brains was compared with T2* on corresponding sections. • Erythrocytic extravasations assess the severity of • erythrocytic extravasations 24hr after CT-tMCAO. Air HBO NBO coronal cryosections Erythrocytic extravasations tMCAO rt-PA 2hr 0hr 1hr 24hr

20. Results

22. MRI-DWI (Lesion volume) TT-tMCAO CT-tMCAO Figure 1. Hyperintense lesion volumes on magnetic resonance diffusion-weighted images at 2.5 and 24 hours after thromboembolic middle cerebral artery occlusion (tMCAO) (mm3).

23. SUMMARY 1 In TT-tMCAO, NBO and HBO significantly reduced lesion volume on DWI compared with air. In CT-tMCAO, only a transient trend toward reduced lesion volume was detected in the HBO group at 2.5 hours but no differences were seen at 24 hours after tMCAO. Oxygen therapy can reducelesion volume after thrombolysis.

24. MRI-T1w(BBB damage) TT-tMCAO CT-tMCAO Figure 2. Volume of enhancement on postcontrast T1w magnetic resonance images 2.5 and 24 hours after thromboembolic middle cerebral artery occlusion (tMCAO) (mm3).

25. SUMMARY 2 In TT-tMCAO, HBO significantly reduced postischemic BBB damage on T1w images. In CT-tMCAO, HBO also significantly reduced postischemic, at 24 hours after tMCAO, whereas NBO failed to attenuate the enhancing volume on T1w Images. Hyperbaric oxygen therapy significantly reducesBBB damageafter thrombolysis.

26. TT-tMCAO BBB damage intracerebral hemorrhage T2* T1w 2.5hr 24hr 24hr 24hr cryosections Figure 3. Correspondence of blood–brain barrier damage, infarct lesion, and secondary hemorrhage.

27. TT-tMCAO MRI assay Lesion volume 24 hr BBB damage 2.5 hr Hemorrhage 24 hr Figure 4. Multimodal magnetic resonance imaging images showing the topography of the parenchymal infarct (diffusion weighted imaging (DWI) at 24 hours), blood–brain barrier permeability (postcontrast T1w at 2.5 hours), and hemorrhage (T2* at 24 hours).

28. CT-tMCAO 24hr Histologic staining-erythrocytic extravasation Contralateral cortex without erythrocytic extravasation Ischemic cortex (score 2) Ischemic striatum (score 4) Figure 5. Erythrocytic extravasation on trichrome-stained coronal brain sections at the level of the bregma +0.26mm (anterior commissure) 24 hours after calcium-induced thromboemboli-middle cerebral artery occlusion without recanalization.

29. Hemoglobin content Figure 6. Hemoglobin spectrophotometry of perfused ischemic brain hemisphere after thromboembolic middle cerebral artery occlusion (tMCAO).

30. TT-tMCAO 24hr Expression of MMP-2 and MMP-9 MMP-9 MMP-2 Figure 7. Expression of matrix metalloproteinase (MMP)-2 and MMP-9 24 hours after thromboembolic middle cerebral artery occlusion (tMCAO).

31. SUMMARY 3 Thus, both NBO and HBO induced a significant reduction in macroscopic hemorrhage on T2* MR image. The area of hypointense T2* signal at 24 hours after MCAO was located within the area of intense postcontrast enhancement on T1w images at 2.5 hours after MACO. In TT-t MCAo and CT-tMCAO, HBO significantly decreased the mean hemoglobin volume. Early increase in BBB permeability appeared to indicate a risk for later secondary hemorrhage. HBO significantly reduces infarct volume, BBBpermeability, hemorrhageand MMP-9 activityafter thrombolysis .

32. Conclusion

33. Oxygen therapy can decreaseinfarct size and BBB damage after thromboembolic ischemia and reduce postthrombolytic intracerebral hemorrhage.

34. Thank you for attention

35. Oxygen therapy in combination with thrombolytic therapy only affects infarct size if recanalization is successful. Oxygen therapyreduce size and frequency of gross parenchymal hemorrhage after thrombolysis- induced reperfusion. HBO and NBO reduce early BBB permeability after tMCAO, which is a marker for subsequent hemorrhagic complications of thrombolysis. Oxygen therapy improves microvascular integrity even in regions that undergo parenchymal infarction

36. 缺血性中風阻塞之機轉不同可分為腦血栓(cerebral thrombosis)腦血栓原發於血管壁，因血液凝固(coagulation)而阻塞，並不移動 。腦栓塞(cerebral embolism)而腦栓塞則是血管壁沒有太大的問題，乃血管上游的漂流物漂下來把血管阻塞。 cerebral thrombosis cerebral embolism

37. 血栓的種類與溶解血栓的種類 一、血栓的種類 􀂙1.靜脈血栓 由於靜脈流速慢、血壓低。 血栓之成因是活化纖維蛋白、攔住血球細胞形成，因為有紅血球的參與，故呈現紅斑狀。 臨床以抗凝血劑為主。 􀂙 2.動脈血栓 動脈管壁厚而有彈性，血流速度變快、血液壓力大。 血栓的形成主要是因血小板附著凝集。 臨床以抗血小板藥物為主。 􀂾 􀂾

38. 抗血栓藥物 1.抗凝血劑(anticoagulant drugs) 2.血栓溶解藥物(thrombolytic drugs) 3.抗血小板藥物(antiplatelet drugs)

39. 血液凝固路徑及抗凝血藥物的作用部位

40. 血栓的溶解機制 􀂙 人體內有一連串的血栓溶解酶存在，即胞漿素(plasmin)，它是一種強力的纖維蛋白溶解酶(fibrinolysin)，平常不具活性的胞漿素原(plasminogen)經活化成胞漿素後才有溶解纖維蛋白作用。

41. 血栓溶解劑血栓溶解劑 血栓溶解劑(thrombolysis agents)可活化胞漿素原 (plasminogen)，又稱為纖維蛋白溶解劑(fibrinolytics)。 當血栓形成後，必須在3~6小時內給藥，血塊的溶解機率很高，超過72小時則無效。 臨床用途：治療深部靜脈栓塞（如肺栓塞）和急性動 脈栓塞，特別是急性心肌梗塞病患的冠狀動脈栓塞。

42. Alteplase Recombinant 1.來源及作用機轉 利用基因重組工程製造之人體的蛋白質，為常用之組織型胞漿素活化劑(t-PA)其特點是只活化已和血栓結合之胞漿素原，對纖維蛋白具有高度選擇性，不易引起全身性的出血現象，靜脈注射給藥，半衰期短，無抗原性。 2.臨床用途：主要用於治療急性心肌梗塞和急性肺栓塞，另改善腦中風病人的後遺症。

43. VO2/VB = 1.39  Hb  SO2 3 ATA Oxygen Content in Blood on HBO Hb bound O2 = 1.39  Hb  SO2 = 1.39 x 14 x 100% 19.7 ml/dl a PO2 + 1.39  Hb  SO2 Total Hgb-bound O2 content, ml/dl Dissolved PO2, mmHg Dissolved O2 = aPO2= 0.003 x 2000 [3 ATA]= 6.0 ml/dl

44. 高壓氧治療（Hyperbaric Oxygen Therapy，HBO） 1. 定義：HBO是指將病人置於大於一大氣壓的高壓艙內（壓力通常介於1至3大氣壓），給予100%的氧氣使病患吸入的一種治療方式。 2. 應用：藉以提高體內含氧濃度，改善組織缺氧、減少腦水腫，並對厭氧菌產生抑菌、殺菌的功能，促進嗜中性白血球殺菌力，降低缺血再灌流中白血球吸附的情形（Leach et al., 1998），促進傷口癒合，進而達到治療目的。