[Myocardial biopsy of Liwen procedure: representability and etiological diagnostic value of cardiac samples obtained by a novel technique in patients with hypertrophic cardiomyopathy].

Objective: To investigate the representability and etiological diagnostic value of myocardium samples obtained from patients with hypertrophic cardiomyopathy (HCM) by transthoracic echocardiography-guided percutaneous intramyocardial septal biopsy (myocardial biopsy of Liwen procedure). Methods: This study was a retrospective case-series analysis. Patients with HCM, who underwent myocardial biopsy of Liwen procedure and radiofrequency ablation in Xijing Hospital, Air Force Military Medical University from July to December 2019, were included. Demographic data (age, sex), echocardiographic data and complications were collected through electronic medical record system. The histological and echocardiographic features, pathological characteristics of the biopsied myocardium of the patients were analyzed. Results: A total of 21 patients (aged (51.2±14.5) years and 13 males (61.9%)) were enrolled. The thickness of ventricular septum was (23.3±4.5)mm and the left ventricular outflow tract gradient was (78.8±42.6)mmHg (1 mmHg=0.133 kPa). Eight patients (38.1%) were complicated with hypertension, 1 patient (4.8%) had diabetes, and 2 patients (9.5%) had atrial fibrillation. Hematoxylin-eosin staining of myocardial samples of HCM patients before radiofrequency ablation evidenced myocytes hypertrophy, myocytes disarray, nuclear hyperchromatism, hypertrophy, atypia, coronary microvessel abnormalities, adipocyte infiltration, inflammatory cell infiltration, cytoplasmic vacuoles, lipofuscin deposition. Interstitial fibrosis and replacement fibrosis were detected in Masson stained biopsy samples. Hematoxylin-eosin staining of myocardial samples of HCM patients after radiofrequency ablation showed significantly reduced myocytes, cracked nuclear in myocytes, coagulative necrosis, border disappearance and nuclear fragmentation. Quantitative analysis of myocardial specimens of HCM patients before radiofrequency ablation showed that there were 9 cases (42.9%) with mild myocardial hypertrophy and 12 cases (57.1%) with severe myocardial hypertrophy. Mild, moderate and severe fibrosis were 5 (23.8%), 9 (42.9%) and 7 (33.3%), respectively. Six cases (28.6%) had myocytes disarray. There were 11 cases (52.4%) of coronary microvessel abnormalities, 4 cases (19.0%) of adipocyte infiltration, 2 cases (9.5%) of inflammatory cell infiltration,6 cases (28.5%) of cytoplasmic vacuole, 16 cases (76.2%) of lipofuscin deposition. The diameter of cardiac myocytes was (25.2±2.8)μm, and the percentage of collagen fiber area was 5.2%(3.0%, 14.6%). One patient had severe replacement fibrosis in the myocardium, with a fibrotic area of 67.0%. The rest of the patients had interstitial fibrosis. The myocardial specimens of 13 patients were examined by transmission electron microscopy. All showed increased myofibrils, and 9 cases had disorder of myofibrils. All patients had irregular shape of myocardial nucleus, partial depression, mild mitochondrial swelling, fracture and reduction of mitochondrial crest, and local aggregation of myofibrillary interfascicles. One patient had hypertrophy of cardiomyocytes, but the arrangement of muscle fibers was roughly normal. There were vacuoles in the cytoplasm, and Periodic acid-Schiff staining was positive. Transmission electron microscopy showed large range of glycogen deposition in the cytoplasm, with occasional double membrane surround, which was highly indicative of glycogen storage disease. No deposition of glycolipid substance in lysozyme was observed under transmission electron microscope in all myocardial specimens, which could basically eliminate Fabry disease. No apple green substance was found under polarized light after Congo red staining, which could basically exclude cardiac amyloidosis. Conclusion: Myocardium biopsied samples obtained by Liwen procedure of HCM patients are representative and helpful for the etiological diagnosis of HCM.目的： 探讨通过经胸超声心动图引导下经皮心肌内室间隔心肌活检术（即Liwen术式心肌活检术）获得的肥厚型心肌病（HCM）患者心肌标本的代表性及其病因学诊断价值。 方法： 该研究为回顾性病例系列分析。纳入2019年7至12月空军军医大学西京医院行Liwen术式心肌活检和射频消融的HCM住院患者。通过电子病历系统收集患者的人口统计学资料（年龄、性别）、超声心动图检查结果及合并症的情况。对所有入选患者的活检心肌组织进行组织学和超微结构观察，并进行组织学阅片，观察HCM患者心肌标本的病理学特征。 结果： 研究共入选患者21例，年龄（51.2±14.5）岁，男性13例（61.9%）。入选患者最大室间隔厚度（23.3±4.5）mm，左心室流出道峰值压差（78.8±42.6）mmHg（1 mmHg=0.133 kPa）；8例（38.1%）合并高血压，1例（4.8%）合并糖尿病，2例（9.5%）合并心房颤动。射频消融术前HCM患者心肌标本苏木素-伊红染色可见心肌细胞肥大，心肌细胞排列紊乱，核深染、肥大、异型，冠状动脉微血管管壁增厚、管腔狭窄，脂肪细胞浸润，炎症细胞浸润，胞浆空泡，脂褐素沉积；马松染色可见间质纤维化和替代纤维化。射频消融术后HCM患者心肌标本苏木素-伊红染色可见心肌细胞明显缩小，裂解，发生凝固性坏死，边界不清，胞核碎裂、消失。射频消融术前HCM患者心肌标本定量分析示，入选患者中轻度和重度心肌细胞肥大分别有9例（42.9%）和12例（57.1%）；轻、中和重度纤维化分别有5例（23.8%）、9例（42.9%）和7例（33.3%）；心肌细胞排列紊乱有6例（28.6%）；冠状动脉微血管异常、脂肪细胞浸润、炎症细胞浸润、胞浆空泡、脂褐素沉积分别有11例（52.4%）、4例（19.0%）、2例（9.5%）、6例（28.5%）、16例（76.2%）。入选患者的心肌细胞直径为（25.2±2.8）μm，胶原纤维面积百分比为5.2%（3.0%，14.6%）。其中1例患者心肌中存在严重替代纤维化，纤维化面积达67.0%。其余患者为间质纤维化改变。对13例患者的心肌标本进行了透射电镜观察，可见患者心肌肌原纤维增多，其中9例肌原纤维排列紊乱。13例患者的心肌细胞核形状不规则，局部凹陷，线粒体轻度肿胀，线粒体嵴断裂、减少，局部聚集肌原纤维束间。1例患者心肌细胞肥大但肌纤维排列大致正常，胞浆内存在空泡，过碘酸雪夫染色阳性，透射电镜观察可见胞浆内存在大范围糖原沉积，偶见双膜环绕，高度提示糖原贮积病。所有心肌标本透射电镜下均未见溶酶体内糖脂样物质沉积，可基本排除法布里病，刚果红染色后偏振光下均未发现苹果绿样物质存在，可基本排除心脏淀粉样变。 结论： 通过Liwen术式心肌活检术获得的HCM患者的心肌标本代表性较好，且有助于HCM的病因学诊断。.