Predicting rupture locations of ascending aortic aneurysms using CT-based finite element models.

Accurate rupture risk assessment of ascending aortic aneurysms is important for reducing aneurysm-related mortality. More recently, computational models have been shown to better predict rupture risk than diameter-based measurements. However, it remains unclear whether finite element (FE) models of the ascending aorta can predict rupture location, and over what timeframe those predictions are reliable. The aim of this study was to evaluate FE models of the ascending aorta generated from computed tomography (CT) scans in predicting rupture location. Pre- and post-rupture CT scans were obtained of 12 patients who underwent emergency surgical repair for ascending aorta rupture with varying time intervals between scans (20 days - 6 years). A rigid iterative closest point (ICP) registration was used to overlay post-rupture aortic geometries with pre-rupture FE models and directly compare predicted regions of high equivalent strain with actual rupture. The FE model predicted the rupture location in the 5 patients with the shortest time intervals between the pre- and post-rupture scans (20 days - 2 years, 3 months). However, rupture location was not predicted in the 4/5 patients with greater than 3 years between scans. Achieving a physiological equivalent strain distribution in the FE model was highly dependent on the resolution of the pre-rupture scan and whether contrast agent was present. The results suggest there may be a time interval beyond which FE predictions of rupture location may not be reliable. The results in this study may help clinical validation of FE models of ascending aortic aneurysms predicting rupture risk.

Thoracoscopic Sympathectomy for Long QT Syndrome. Literature Review and Case Study.

BACKGROUND: Multiple case studies have suggested that video-assisted thoracoscopic sympathectomy (VATS) reduces the occurrence and frequency of symptoms in long QT syndrome (LQTS) [1,2,3]. To date there has not been a literature review to report on the short-term and long-term outcomes of this procedure. Our primary aims are to review the literature findings on the clinical outcomes of VATS sympathectomy for long QT and present a local centre case report on the outcomes of T2-T5 sympathectomy. METHODS: Relevant articles were identified by a systematic search of PubMed, Cochrane and Scopus databases, from November 1985 to October 2015. A total of 520 patients from 21 publications were included for analysis and discussion in three main areas: presenting symptoms and indication for surgery, perioperative complications, and patient quality of life following surgery. Our case study reviews a 49-year-old female with recently diagnosed long QT syndrome and intolerance to beta blocker therapy successfully managed with T2-T5 thoracic sympathectomy. RESULTS: The most common presenting indication for operative management of long QT syndrome was syncope (208/520 patients) and tachyarrhythmia (207/520 patients). T1-T5 left sympathectomy was performed in 15/21 published reports (332/520 patients) with partial stellate removal or in its entirety. Follow-up of patients ranged from 1 month to 11 years. Four patients died in the postoperative period, from fatal arrhythmias. The most common postoperative findings were no symptoms (64/520 patients); tachyarrhythmia (55/520 patients), syncope (45/520 patients), and Horner's syndrome (13/520 patients with 27 patients reporting associated symptoms). Thirteen cases reported on the QTc changes post sympathectomy and 9/13 cases involving 220/520 patients showed marked QTc reduction following surgery. Mean preoperative QTc was 558ms and median 559ms. Mean postoperative QTc was 476ms and median 466ms. Our patient showed a marked reduction in QTc following surgery, with no evidence of arrhythmias and reduced beta blocker dependence. CONCLUSIONS: Surgical management of LQTS has historically involved a left cervicothoracic stellectomy removing stellate ganglia and typically part of the left thoracic sympathetic chain resulting in reduction in symptoms but increasing the risk of Horner's syndrome and intermittent temperature changes [4,5]. Surgical resection of the thoracic ganglia alone for management of LQTS is scarce in the literature. Short-term follow-up in our case study following a T2-T5 sympathectomy revealed reduction in symptoms, no requirement for beta blocker therapy and reduced QTc interval. Further follow-up using greater patient numbers will further support T2-T5 sympathectomy as an option for surgical management of LQTS.