Displaying all 15 publications

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  1. Chong MY, Gu B, Chan BT, Ong ZC, Xu XY, Lim E
    Int J Numer Method Biomed Eng, 2020 12;36(12):e3399.
    PMID: 32862487 DOI: 10.1002/cnm.3399
    A monolithic, fully coupled fluid-structure interaction (FSI) computational framework was developed to account for dissection flap motion in acute type B aortic dissection (TBAD). Analysis of results included wall deformation, pressure, flow, wall shear stress (WSS), von Mises stress and comparison of hemodynamics between rigid wall and FSI models. Our FSI model mimicked realistic wall deformation that resulted in maximum compression of the distal true lumen (TL) by 21.4%. The substantial movement of intimal flap mostly affected flow conditions in the false lumen (FL). Flap motion facilitated more flow entering the FL at peak systole, with the TL to FL flow split changing from 88:12 in the rigid model to 83:17 in the FSI model. There was more disturbed flow in the FL during systole (5.8% FSI vs 5.2% rigid) and diastole (13.5% FSI vs 9.8% rigid), via a λ2 -criterion. The flap-induced disturbed flow near the tears in the FSI model caused an increase of local WSS by up to 70.0% during diastole. This resulted in a significant reduction in the size of low time-averaged WSS (TAWSS) regions in the FL (113.11 cm2 FSI vs 177.44 cm2 rigid). Moreover, the FSI model predicted lower systolic pressure, higher diastolic pressure, and hence lower pulse pressure. Our results provided new insights into the possible impact of flap motion on flow in aortic dissections, which are particularly important when evaluating hemodynamics of acute TBAD. NOVELTY STATEMENT: Our monolithic fully coupled FSI computational framework is able to reproduce experimentally measured range of flap deformation in aortic dissection, thereby providing novel insights into the influence of physiological flap motion on the flow and pressure distributions. The drastic flap movement increases the flow resistance in the true lumen and causes more disturbed flow in the false lumen, as visualized through the λ2 criterion. The flap-induced luminal pressure is dampened, thereby affecting pressure measures, which may serve as potential prognostic indicators for late complications in acute uncomplicated TBAD patients.
    Matched MeSH terms: Aneurysm, Dissecting*
  2. Raffali MAA, Azmi MI, Muhammad SF, Che Hassan HH
    BMJ Case Rep, 2024 Apr 29;17(4).
    PMID: 38684352 DOI: 10.1136/bcr-2024-260649
    A man in his 20s with no medical illness sustained a blunt chest injury with pneumothorax and lung contusion after involving in a motorbike accident. Five days postadmission, he subsequently had myocardial infarction with cardiac arrest, in which coronary angiogram and intravascular ultrasound showed diffused multivessel coronary artery dissection.
    Matched MeSH terms: Aneurysm, Dissecting/complications; Aneurysm, Dissecting/etiology
  3. Tan GJS, Khoo PLZ, Sailesh MK, Chan KMJ
    Med J Malaysia, 2019 02;74(1):67-78.
    PMID: 30846666
    INTRODUCTION: Aortic disease includes conditions such as chronic aortic aneurysms, acute aortic syndromes and congenital aortic abnormalities, amongst others. This paper reviews all research on aortic disease performed in Malaysia and published between 2000-2016.

    METHODS: A literature search was conducted in PubMed, Scopus, MyJurnal and the UKM Journal Repository. The search process was based on a previously published methodology. The medical subject headings (MeSH) search terms used were "aortic", "aorta" and "Malaysia".

    RESULTS: Two-hundred-thirteen papers were identified, of which 60 papers were selected and reviewed on the basis of their relevance. The epidemiology, pathophysiology, clinical presentations, case reports, investigations, treatment and outcomes of aortic disease in Malaysia were reviewed and summarised. The clinical relevance of the studies performed are discussed.

    CONCLUSION: The review provided an insight into the pathophysiology, prevalence and epidemiology of aortic diseases in Malaysia, how the condition is managed, and the outcomes of treatment. Limitations of the research performed in Malaysia to date were identified and recommendations for further research and improvement in clinical practice were recommended.

    Matched MeSH terms: Aneurysm, Dissecting/diagnosis; Aneurysm, Dissecting/epidemiology; Aneurysm, Dissecting/therapy
  4. Wan Ab Naim WN, Ganesan PB, Sun Z, Lei J, Jansen S, Hashim SA, et al.
    Int J Numer Method Biomed Eng, 2018 05;34(5):e2961.
    PMID: 29331052 DOI: 10.1002/cnm.2961
    Endovascular stent graft repair has become a common treatment for complicated Stanford type B aortic dissection to restore true lumen flow and induce false lumen thrombosis. Using computational fluid dynamics, this study reports the differences in flow patterns and wall shear stress distribution in complicated Stanford type B aortic dissection patients after endovascular stent graft repair. Five patients were included in this study: 2 have more than 80% false lumen thrombosis (group 1), while 3 others had less than 80% false lumen thrombosis (group 2) within 1 year following endovascular repair. Group 1 patients had concentrated re-entry tears around the abdominal branches only, while group 2 patients had re-entry tears that spread along the dissection line. Blood flow inside the false lumen which affected thrombus formation increased with the number of re-entry tears and when only small amounts of blood that entered the false lumen exited through the branches. In those cases where dissection extended below the abdominal branches (group 2), patients with fewer re-entry tears and longer distance between the tears had low wall shear stress contributing to thrombosis. This work provides an insight into predicting the development of complete or incomplete false lumen thrombosis and has implications for patient selection for treatment.
    Matched MeSH terms: Aneurysm, Dissecting/surgery*
  5. Yew KL
    Int J Cardiol, 2014 Dec 20;177(3):1127-8.
    PMID: 25150482 DOI: 10.1016/j.ijcard.2014.08.056
    Matched MeSH terms: Aneurysm, Dissecting/etiology; Aneurysm, Dissecting/radiography*; Aneurysm, Dissecting/therapy*
  6. Nik Azlan NM, Rossman H
    Med J Malaysia, 2017 06;72(3):193-194.
    PMID: 28733569 MyJurnal
    We are reporting a case of missed blunt traumatic aortic injury (BTAI). A 28 year male presented with chest pain following a motor vehicle accident. He was discharged following normal clinical signs and chest radiograph. The following day he complained of lower limb weakness. Traumatic aortic dissection was revealed via computer tomography (CT) of the thorax. BTAI cannot be ruled out with normal clinical signs and chest radiograph alone. CT thorax is mandatory to rule out BTAI in high impact chest injury.
    Matched MeSH terms: Aneurysm, Dissecting/diagnosis; Aneurysm, Dissecting/etiology
  7. Tan WT, Liew YM, Mohamed Mokhtarudin MJ, Pirola S, Wan Ab Naim WN, Amry Hashim S, et al.
    J Biomech Eng, 2021 Aug 01;143(8).
    PMID: 33764388 DOI: 10.1115/1.4050642
    A computational approach is used to investigate potential risk factors for distal stent graft-induced new entry (dSINE) in aortic dissection (AD) patients. Patient-specific simulations were performed based on computed tomography images acquired from six AD patients (three dSINE and three non-dSINE) to analyze the correlation between anatomical characteristics and stress/strain distributions. Sensitivity analysis was carried out using idealized models to independently assess the effect of stent graft length, stent tortuosity and wedge apposition angle at the landing zone on key biomechanical variables. Mismatch of biomechanical properties between the stented and nonstented regions led to high stress at the distal stent graft-vessel interface in all patients, as well as shear strain in the neighboring region, which coincides with the location of tear formation. Stress was observed to increase with the increase of stent tortuosity (from 263 kPa at a tortuosity angle of 50 deg to 313 kPa at 30 deg). It was further amplified by stent graft landing at the inflection point of a curve. Malapposition of the stent graft led to an asymmetrical segment within the aorta, therefore changing the location and magnitude of the maximum von Mises stress substantially (up to +25.9% with a +25 deg change in the distal wedge apposition angle). In conclusion, stent tortuosity and wedge apposition angle serve as important risk predictors for dSINE formation in AD patients.
    Matched MeSH terms: Aneurysm, Dissecting/physiopathology; Aneurysm, Dissecting/surgery
  8. Mohamed-Yassin MS, Baharudin N, Ramli AS, Hashim H
    Malays Fam Physician, 2019;14(1):47-52.
    PMID: 31289633
    It remains a challenge to diagnose aortic dissection in primary care, as classic clinical features are not always present. This case describes an atypical presentation of aortic dissection, in which the patient walked in with pleuritic central chest pain associated with a fever and elevated C-reactive protein. Classic features of tearing pain, pulse differentials, and a widened mediastinum on chest X-ray were absent. This unusual presentation highlights the need for a heightened level of clinical suspicion for aortic dissection in the absence of classic features. The case is discussed with reference to the literature on the sensitivity and specificity of the classic signs and symptoms of aortic dissection. A combination of the aortic dissection detection risk score (ADD-RS) and D-dimer test is helpful in ruling out this frequently lethal condition.
    Matched MeSH terms: Aneurysm, Dissecting
  9. Wan Ab Naim WN, Sun Z, Liew YM, Chan BT, Jansen S, Lei J, et al.
    Quant Imaging Med Surg, 2021 May;11(5):1723-1736.
    PMID: 33936960 DOI: 10.21037/qims-20-814
    Background: The study aims to analyze the correlation between the maximal diameter (both axial and orthogonal) and volume changes in the true (TL) and false lumens (FL) after stent-grafting for Stanford type B aortic dissection.

    Method: Computed tomography angiography was performed on 13 type B aortic dissection patients before and after procedure, and at 6 and 12 months follow-up. The lumens were divided into three regions: the stented area (Region 1), distal to the stent graft to the celiac artery (Region 2), and between the celiac artery and the iliac bifurcation (Region 3). Changes in aortic morphology were quantified by the increase or decrease of diametric and volumetric percentages from baseline measurements.

    Results: At Region 1, the TL diameter and volume increased (pre-treatment: volume =51.4±41.9 mL, maximal axial diameter =22.4±6.8 mm, maximal orthogonal diameter =21.6±7.2 mm; follow-up: volume =130.7±69.2 mL, maximal axial diameter =40.1±8.1 mm, maximal orthogonal diameter =31.9+2.6 mm, P<0.05 for all comparisons), while FL decreased (pre-treatment: volume =129.6±150.5 mL; maximal axial diameter =43.0±15.8 mm; maximal orthogonal diameter =28.3±12.6 mm; follow-up: volume =66.6±95.0 mL, maximal axial diameter =24.5±19.9 mm, maximal orthogonal diameter =16.9±13.7, P<0.05 for all comparisons). Due to the uniformity in size throughout the vessel, high concordance was observed between diametric and volumetric measurements in the stented region with 93% and 92% between maximal axial diameter and volume for the true/false lumens, and 90% and 92% between maximal orthogonal diameter and volume for the true/false lumens. Large discrepancies were observed between the different measurement methods at regions distal to the stent graft, with up to 46% differences between maximal orthogonal diameter and volume.

    Conclusions: Volume measurement was shown to be a much more sensitive indicator in identifying lumen expansion/shrinkage at the distal stented region.

    Matched MeSH terms: Aneurysm, Dissecting
  10. Subramaniam K, Hasmi AH, Mahmood MS
    Malays J Pathol, 2014 Dec;36(3):213-6.
    PMID: 25500522 MyJurnal
    Ruptured dissecting aortic aneurysm more commonly occur in men in the 40 to 70 age group, and most commonly is associated with atherosclerosis. Uncommon causes are previous heart surgery, connective tissue disorders and aortitis. Despite its rarity, Clostridium spp aortitis progresses very rapidly with a mortality rate of approximately 79% in adults, typically occurring within 48 hours of infection. We present a case of sudden death due to clostridial aortitis causing ruptured aortic dissection in an apparently healthy adult female, 7 weeks post-spontaneous vaginal delivery. This case highlights the pathology of aortic dissection and cystic media necrosis as presentations of clostridium spp infection in young female adult.
    Matched MeSH terms: Aneurysm, Dissecting/microbiology*
  11. Velayudhan BV, Idhrees M, Matalanis G, Park KH, Tang D, Sfeir PM, et al.
    J Cardiovasc Surg (Torino), 2020 Jun;61(3):285-291.
    PMID: 32337940 DOI: 10.23736/S0021-9509.20.11397-1
    Acute type A aortic dissection remains one of the most challenging conditions in aortic surgery. Despite the advancements in the field, the mortality rate still remains high. Though there is a general consensus that the ascending aorta should be replaced, the distal extension of the surgery still remains a controversy. Few surgeons argue for a conservative approach to reduce operative and postoperative morbidity while others considering the problems associated with "downstream problems" support an aggressive approach including a frozen elephant trunk. The cohort in the Indian subcontinent and APAC is far different from the western world. Many factors determine the decision for surgery apart from the pathology of the disease. Economy, availability of the suitable prosthesis, the experience of the surgeon, ease of access to the medical facility all contribute to the decision making to treat acute type A dissection.
    Matched MeSH terms: Aneurysm, Dissecting/surgery*
  12. Rahman MR, Min JO, Dimon MZ
    Heart Surg Forum, 2010 Aug;13(4):E273-4.
    PMID: 20719738 DOI: 10.1532/HSF98.20101001
    Delayed ascending aortic dissection following coronary artery bypass surgery is a rare but lethal complication. We present the case of a 54-year-old man with a delayed acute Stanford A aortic dissection following an off-pump coronary artery bypass surgery in preexisting chronic type B disease. Such a case of an iatrogenic acute aortic dissection poses a significant challenge and dilemma in choosing the best technique for coronary revascularization in this group of patients. The pathophysiology and technical options are discussed.
    Matched MeSH terms: Aneurysm, Dissecting/complications; Aneurysm, Dissecting/etiology*; Aneurysm, Dissecting/radiography; Aneurysm, Dissecting/surgery
  13. Kosai, N.R., Reynu, R., Abdikarim, M., Abdikarim, M., Taher, M.M., Idris, M.A., et al.
    Medicine & Health, 2014;9(2):143-149.
    MyJurnal
    The diagnosis of aortic dissection in a young adult in the absence of atherosclerosis or prior history of trauma is extremely rare. The presence of more than one arterial dissection site in such a patient is even more unheard of. We highlight a case of spontaneous multiple acute arterial dissections occurring in a 32-year-old male. Stanford B aortic dissection and a separate dissection extending from the bifurcation of the right common iliac artery to the right common femoral artery was noted on computed tomographic angiography (CTA). A small aneurysm of the right subclavian artery was also noted. A two-stage hybrid procedure involving a combination of open and endovascular surgery was employed. The rarity and lethality of this condition warrants a high index of suspicion for early diagnosis and prompt intervention.
    Matched MeSH terms: Aneurysm, Dissecting
  14. Subramaniam K, Sheppard MN
    J Forensic Leg Med, 2018 Feb;54:127-129.
    PMID: 29413954 DOI: 10.1016/j.jflm.2018.01.005
    OBJECTIVES: Aortic dissection (AD) can be a challenging diagnosis. At autopsy, the aorta may not be dilated and intimal tears may be missed or found without obvious rupture or haemorrhage. We report our experience of AD at a tertiary referral centre with review of 32 cases and discuss 2 unusual complications.

    METHODS/RESULTS: 32 cases of which 12 females and 20 male and 18 out of 32 cases were aged below 40. All of the cases were examined macroscopically and microscopically. 30 out of 32 cases (93%) died due to rupture associated with the AD. Two unusual complications were proximal extension of AD into left coronary artery (CA) with intramural haematoma blocking the vessel and AD involving the ostium of the right CA resulting in avulsion of the right CA from the aorta. Mode of death in both these cases were myocardial ischemia. Sections of the aorta in all cases confirmed extensive cystic medial degeneration with disorganisation, fragmentation and disappearance of the elastin fibres with increased collagen and smooth muscle nuclear degeneration.

    CONCLUSION: Pathologists should be thorough when examining the aorta, the aortic valve and root in AD. When a rupture site cannot be found it is important to look for unusual complications involving the CAs. Histology plays an important role to corroborate the cause of death.

    Matched MeSH terms: Aneurysm, Dissecting/pathology*
  15. Zubaidah NH, Azim MI, Osama MH, Harunarashid H, Das S
    Clin Ter, 2012;163(1):27-9.
    PMID: 22362230
    The incidence of infection following TEVAR is low. To the best of our knowledge, this is the first case report of post thoracic endovascular aortic repair (TEVAR) with Streptococcus viridans graft infection. A 54-year-old male underwent TEVAR for dissecting thoracic aneurysm with spinal ischaemia. He had an eventful recovery with prolonged period of stay in intensive care unit. Three months later, he presented with persistent chest discomfort and fever. Computed tomography (CT) of the thorax revealed evidence of graft infection and the blood culture grew Streptococcus viridans. The rarity of TEVAR graft infection due to Streptococcus viridans and its management are being discussed.
    Matched MeSH terms: Aneurysm, Dissecting/complications; Aneurysm, Dissecting/surgery*
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