Carlsson Marcus, Martin Alastair J, Ursell Philip C, Saloner David, Saeed Maythem
Department of Radiology and Biomedical Imaging, University of California, San Francisco, San Francisco, California 94134, USA.
Magn Reson Med. 2009 Mar;61(3):595-602. doi: 10.1002/mrm.21869.
Microembolization is common after coronary interventions, and therefore this MRI study aimed to quantify the effect of coronary microembolization on left ventricular (LV) function. The left anterior descending artery (LAD) was selectively catheterized in an XMR suite (Philips Medical Systems, Best, The Netherlands) in eight pigs to deliver MR contrast media to measure the LAD territory using first-pass perfusion and for intracoronary delivery of the embolic agent. Cine, tagged, and delayed contrast-enhanced MRI (DCE-MRI) was performed to assess LV volumes, ejection fraction, radial and circumferential strain, and viability at baseline, 1 h, and 1 week after microembolization. Histopathology and histochemical staining were used to characterize and measure the extent of microinfarction. The LAD territory was 35% +/- 2% LV mass. Patchy microinfarction on DCE-MRI at 1 week was 22.0% +/- 3.6% LAD territory (7.5% LV mass). Microembolization caused persistent decline in ejection fraction (baseline = 49% +/- 1%, 1 h = 29% +/- 1%, P = 0.02 and 1 week = 36% +/- 1%, P = 0.03) and increased end-diastolic (79.6 +/- 3.9 ml, 85.5 +/- 4.5 ml, P = 0.03 and 92.4 +/- 6.2 ml, P = 0.06, respectively) and end-systolic (40.8 +/- 2.1 ml, 60.2 +/- 3.4 ml, P = 0.02 and 59.3 +/- 4.8 ml, P = 0.03, respectively) volumes. The microembolized territory was manifested as dysfunctional regions for 1 week on cine and tagged MRI. Histopathology revealed occlusive microemboli surrounded by necrotic tissue undergoing repair. Microinfarction was visualized after coronary microembolization and caused LV dysfunction disproportionate to the size of myocardial damage. It also changed LV geometry and decreased radial and circumferential strain over the course of 1 week.
微栓塞在冠状动脉介入治疗后很常见，因此这项MRI研究旨在量化冠状动脉微栓塞对左心室（LV）功能的影响。在八头猪的XMR设备（飞利浦医疗系统公司，荷兰贝斯特）中，选择性地将导管插入左前降支（LAD），以输送MR造影剂，通过首过灌注测量LAD区域，并用于冠状动脉内输送栓塞剂。在微栓塞前、微栓塞后1小时和1周时，进行电影、标记和延迟对比增强MRI（DCE-MRI），以评估左心室容积、射血分数、径向和圆周应变以及心肌存活性。使用组织病理学和组织化学染色来表征和测量微梗死的范围。LAD区域占左心室质量的35%±2%。在1周时，DCE-MRI上的斑片状微梗死占LAD区域的22.0%±3.6%（占左心室质量的7.5%）。微栓塞导致射血分数持续下降（基线时为49%±1%，1小时时为29%±1%，P = 0.02；1周时为36%±1%，P = 0.03），舒张末期容积（分别为79.6±3.9 ml、85.5±4.5 ml，P = 0.03；以及92.4±6.2 ml，P = 0.06）和收缩末期容积（分别为40.8±2.1 ml、60.2±3.4 ml，P = 0.02；以及59.3±4.8 ml，P = 0.03）增加。在电影和标记MRI上，微栓塞区域在1周内表现为功能障碍区域。组织病理学显示，闭塞性微栓子被正在修复的坏死组织包围。冠状动脉微栓塞后可见微梗死，且导致左心室功能障碍与心肌损伤大小不成比例。它还改变了左心室几何形状，并在1周内降低了径向和圆周应变。
