Shahrul Hashim

A Perspective Review on Numerical Simulations of Hemodynamics in Aortic Dissection

Aortic dissection, characterized by separation of the layers of the aortic wall, poses a significant challenge for clinicians. While type A aortic dissection patients are normally managed using surgical treatment, optimal treatment strategy for type B aortic dissection remains controversial and requires further evaluation. Although aortic diameter measured by CT angiography has been clinically used as a guideline to predict dilation in aortic dissection, hemodynamic parameters (e.g., pressure and wall shear stress), geometrical factors, and composition of the aorta wall are known to substantially affect disease progression. Due to the limitations of cardiac imaging modalities, numerical simulations have been widely used for the prediction of disease progression and therapeutic outcomes, by providing detailed insights into the hemodynamics. This paper presents a comprehensive review of the existing numerical models developed to investigate reasons behind tear initiation and progression, as well as the effectiveness of various treatment strategies, particularly the stent graft treatment.

Hemangiopericytoma 11 years later: delayed recurrence of a rare soft tissue sarcoma

Hemangiopericytomas (HPCs) are uncommon tumours. We present the case of a 41-year-old female with multiple resections at different sites over the course of 11 years. The approach considerations, as well as treatment options and prognosis are discussed. A 41-year-old female with two previous resections for intracranial meningeal HPC in 2004 and 2008, as well as adjuvant radiotherapy, presented in 2015 with left intrathoracic and left hip recurrence confirmed by positron emission tomography/computed tomography (PET/CT). She underwent left proximal femur resection/reconstruction and video-assisted thoracoscopic surgery (VATS) resection of the intrathoracic tumour was attempted. She was discharged home on her 4th post-operative day with minimal pain. There were no neurosensory or motor deficits. Any patient who has been diagnosed with HPC in the past who develops new symptoms should be worked up for recurrence, regardless of the length of disease-free interval, as our case study suggested. There has yet to be a standardized follow-up regime due to the rarity of these tumours. HPC remains a rare soft tissue sarcoma with high recurrence rate. Planned VATS evaluation and resection is possible provided complete resection with clear surgical margins can be achieved, as clear surgical margins offer the best chance of survival.

Electromechanics modeling of the effects of myocardial infarction on left ventricular function

Ventricular remodeling may occur following myocardial infarction of the left ventricle (LV) and such remodeling has been shown to be correlated with increased patient morbidity and mortality. It is thus important to estimate the likelihood of remodeling from the state of the infarcted LV. In this paper, we present simulations from an actively-contracting truncated ellipsoid LV model, incorporating realistic fiber orientation and electromechanical properties, to investigate the effects of infarct size and transmural extent (TME) on myofiber regional mechanics. Results showed that transmural infarcts greatly elevated both the myofiber stress and strain at the border zone during end systole, making the LV more susceptible to structural remodeling. It was found that TME rather than infarct size was more predictive of LV remodeling.

Metastatic Adenocarcinoma Presenting as Extensive Cavoatrial Tumor Thrombus.

The presence of tumor thrombus in the right atrium is frequently the result of direct intraluminal extension of infra-diaphragmatic malignancy into the inferior vena cava (IVC) or supradiaphragmatic carcinoma into the superior vena cava (SVC). Right atrial tumor thrombus with extension into both SVC and IVC has not been reported in the literature. We present a patient who presented with symptoms of right atrial and SVC obstruction. Imaging revealed presence of a thrombus in the right atrium, extending to the SVC and IVC, with the additional findings of a left adrenal mass and multiple liver lesions. The histopathological examination of the right atrial mass revealed metastatic adenocarcinoma cells. The patient was given a presumptive diagnosis of metastatic adenocarcinoma, most likely adrenal in origin, with multiple hepatic lesions suspicious for metastasis. The clinical outcome of the patient was not favorable; the patient succumbed before the adrenal mass could be confirmed to be the primary tumor. This case highlights that in patients manifesting with extensive cavoatrial thrombus as, the existence of primary carcinoma should be considered especially in the adrenal cortex or in the lung.

Biomodelling Methods Employed to Reconstruct Three Dimension Anatomically Accurate Substructures of the Human Cardiac Anatomy

Biomodeling is an important method to analyse the human anatomy. A spatially accurate three dimensional (3D) biomodel recreated from a computed tomography (CT) scans allow for various extended use. One major use would be as an instructional kit to train junior surgeons because of its exact replica of the actual anatomy in positions relative to each other. The approach has been extensively pursued by the primary author with neuro-, maxillofacial and otolaryngology surgeons. In the field of cardiothoracic surgery, the utility of biomodels is further emphasised because the cadaveric heart collapses post mortem thus making it ineffective to be used to train surgical residents to identify the sub-structures of cardiac anatomy. A gated and contrasted CT scan of the second author was performed. This paper discusses the 3D image processing and modelling methods and suggests the combined use of B-spline algorithm to reproduce aortic sub-structures from CT scans. Comparisons and methods to make a biomodel suitable to be 3D printed on a rapid prototyping apparatus are elucidated. Effort is currently underway to utilise the presented method to recreate a spatially accurate and complete structure of the human cardiac biomodel.

Bilateral pulmonary sequestrations mimicking advanced lung malignancy

Bilateral pulmonary sequestrations are extremely rare and uncommonly diagnosed during adulthood. It can present with severe symptoms such as hemoptysis. It can also be misdiagnosed as a primary lung malignancy.

A Flowmeter Technique to Exclude Internal Mammary Artery Anastomosis Error in an Arrested Heart

The revision of an internal mammary artery graft anastomosis because of a technical error can be time-consuming and complicated and may lead to complications. Here, we describe the technical details and our early experience of using a standard transit-time flowmeter to exclude technical errors and facilitate rapid decision making for anastomosis revision in an arrested heart during aortic cross-clamping in the absence of ultrasound guidance.