Krishnaswamy Rohan Joshua, Sivasubramaniam Vanathi, Robson Desiree, Hayward Christopher Simon, Muthiah Kavitha
Heart and Lung Transplant Unit, St Vincent's Hospital, Darlinghurst, Sydney, NSW 2010, Australia.
Faculty of Medicine, University of New South Wales, Kensington, NSW 2033, Australia.
Eur Heart J Case Rep. 2024 Nov 5;8(12):ytae592. doi: 10.1093/ehjcr/ytae592. eCollection 2024 Dec.
Subaortic pannus formation complicates bioprosthetic aortic valve (AV) replacement. We report an extreme case in a continuous-flow left ventricular assist device (LVAD) patient.
A 49-year-old Caucasian female with dilated cardiomyopathy was bridged to transplant with a HeartWare Ventricular Assist Device (Medtronic). Duration of support was prolonged, 6 years & 7 months, due to allosensitization requiring desensitization. Pump thrombosis occurred 2 years & 4 months post-LVAD requiring alteplase thrombolysis. The patient underwent bioprosthetic AV replacement 3 years & 10 months post-LVAD for symptomatic aortic incompetence. Transthoracic echocardiography (TTE) performed 1 year and 2 years post-bioprosthetic AV replacement repeatedly demonstrated an AV closed during all cardiac cycles without incompetence and nil flow through the left ventricular outflow tract (LVOT). Following transplant, analysis of explanted heart revealed a fused AV. A pannus adherent to the underside of the AV had formed across the entire AV outlet, with complete obliteration of LVOT. This subaortic pannus was not visualized on previous TTE. Histologically, the pannus consisted of hypocellular fibrous tissue with chronic inflammatory cells, spindle histiocytes, and myofibroblasts scattered throughout the loose fibromyxoid stroma, the latter highlighted on CD68 immunohistochemical stain (IHC). Partial endothelialization on the pannus surface was highlighted on ERG and CD31 IHC. Neither calcification nor signs of acute inflammation were noted. In contrast to previous cases, there was no evidence of associated thrombus macroscopically or microscopically.
Prolonged LVAD support may facilitate subaortic pannus following bioprosthetic AV replacement due to AV closure and altered transvalvular flow. Due to the parallel LVAD circulation, subaortic pannus may develop asymptomatically, without haemodynamic compromise, allowing progression to total LVOT obstruction. This requires consideration prior to LVAD explantation in bridge-to-recovery patients.
主动脉瓣下赘生物形成使生物人工心脏主动脉瓣置换术变得复杂。我们报告了一例连续流左心室辅助装置（LVAD）患者的极端病例。
一名49岁患有扩张型心肌病的白种女性通过植入HeartWare心室辅助装置（美敦力公司）过渡到心脏移植。由于需要脱敏治疗的同种异体致敏，支持时间延长至6年7个月。LVAD植入后2年4个月发生泵血栓形成，需要进行阿替普酶溶栓治疗。该患者在LVAD植入后3年10个月因有症状的主动脉瓣关闭不全接受了生物人工心脏主动脉瓣置换术。生物人工心脏主动脉瓣置换术后1年和2年进行的经胸超声心动图（TTE）检查反复显示，在所有心动周期中主动脉瓣均关闭，无关闭不全，左心室流出道（LVOT）无血流。心脏移植后，对切除的心脏进行分析发现主动脉瓣融合。一个附着在主动脉瓣下方的赘生物横跨整个主动脉瓣出口形成，导致LVOT完全闭塞。之前的TTE未发现该主动脉瓣下赘生物。组织学上，赘生物由细胞成分较少的纤维组织组成，伴有慢性炎症细胞、梭形组织细胞和成肌纤维细胞，散在于疏松的纤维黏液样基质中，后者在CD68免疫组织化学染色（IHC）中显色。在ERG和CD31 IHC中，赘生物表面的部分内皮化显色。未发现钙化或急性炎症迹象。与之前的病例不同，在宏观或微观上均未发现相关血栓的证据。
由于主动脉瓣关闭和跨瓣血流改变，延长的LVAD支持可能会促使生物人工心脏主动脉瓣置换术后主动脉瓣下赘生物的形成。由于LVAD循环并行，主动脉瓣下赘生物可能无症状地发展，不影响血流动力学，从而进展为完全性LVOT梗阻。这在桥接至康复患者的LVAD取出术前需要加以考虑。
