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Biliary cystadenoma: A rare occurrence

Peh KH, Eugene Chan BT

Med J Malaysia, 2020 05;75(3):307-308.
PMID: 32467552

Biliary cystadenoma is a rare benign tumour with the potential to transform into malignant carcinoma of the biliary ductal system. There is difficulty in differentiating a benign one from a malignant biliary cystadenoma, and therefore these lesions should always be completely resected. We report a case of biliary cystadenoma which underwent a complete resection.
Effect of spatial inlet velocity profiles on the vortex formation pattern in a dilated left ventricle

Chan BT, Lim E, Ong CW, Abu Osman NA

Comput Methods Biomech Biomed Engin, 2015;18(1):90-6.
PMID: 23521137 DOI: 10.1080/10255842.2013.779683

Despite the advancement of cardiac imaging technologies, these have traditionally been limited to global geometrical measurements. Computational fluid dynamics (CFD) has emerged as a reliable tool that provides flow ﬁeld information and other variables essential for the assessment of the cardiac function. Extensive studies have shown that vortex formation and propagation during the filling phase acts as a promising indicator for the diagnosis of the cardiac health condition. Proper setting of the boundary conditions is crucial in a CFD study as they are important determinants, that affect the simulation results. In this article, the effect of different transmitral velocity profiles (parabolic and uniform profile) on the vortex formation patterns during diastole was studied in a ventricle with dilated cardiomyopathy (DCM). The resulting vortex evolution pattern using the uniform inlet velocity profile agreed with that reported in the literature, which revealed an increase in thrombus risk in a ventricle with DCM. However the application of a parabolic velocity profile at the inlet yields a deviated vortical flow pattern and overestimates the propagation velocity of the vortex ring towards the apex of the ventricle. This study highlighted that uniform inlet velocity profile should be applied in the study of the filling dynamics in a left ventricle because it produces results closer to that observed experimentally.
Review on CFD simulation in heart with dilated cardiomyopathy and myocardial infarction

Chan BT, Lim E, Chee KH, Abu Osman NA

Comput Biol Med, 2013 May;43(4):377-85.
PMID: 23428371 DOI: 10.1016/j.compbiomed.2013.01.013

The heart is a sophisticated functional organ that plays a crucial role in the blood circulatory system. Hemodynamics within the heart chamber can be indicative of exert cardiac health. Due to the limitations of current cardiac imaging modalities, computational fluid dynamics (CFD) have been widely used for the purposes of cardiac function assessment and heart disease diagnosis, as they provide detailed insights into the cardiac flow field. An understanding of ventricular hemodynamics and pathological severities can be gained through studies that employ the CFD method. In this research the hemodynamics of two common myocardial diseases, dilated cardiomyopathy (DCM) and myocardial infarction (MI) were investigated, during both the filling phase and the whole cardiac cycle, through a prescribed geometry and fluid structure interaction (FSI) approach. The results of the research indicated that early stage disease identification and the improvement of cardiac assisting devices and therapeutic procedures can be facilitated through the use of the CFD method.
Treatment of chronic back pain using indirect vibroacoustic therapy: A pilot study

Lim E, Lim R, Suhaimi A, Chan BT, Wahab AKA

J Back Musculoskelet Rehabil, 2018;31(6):1041-1047.
PMID: 30149436 DOI: 10.3233/BMR-171042

BACKGROUND: Low frequency sound wave stimulation therapy has become increasingly popular in the rehabilitation fields, due to its ease, less fatiguing and time efficient application.
OBJECTIVE: This 12-week pilot study examines the efficacy of applying low frequency sound wave stimulation (between 16-160 Hz) through both hands and feet on relieving pain and improving functional ability in patients with chronic back pain.
METHODS: Twenty-three participants with chronic shoulder (eleven participants) or low back pain (twelve participants) underwent a 12-week vibration therapy program of three sessions per week. A low frequency sound wave device comprising four piezoelectric vibration-type tactile tranducers enclosed in separate 5-cm diameter circular plates, which generate sinusoidal vibratory stimuli at a frequency of 16-160 Hz, was used in this study. Primary outcome measure was pain sensation measured using the Visual Analogue Scale (P-VAS). The secondary outcome measures were pain-related disability measured using the pain disability index (PDI) and quality of life measured using the SF-12.
RESULTS: At week 12, significant reductions in pain sensation and pain-related disability were observed, with mean reductions of 3.5 points in P-VAS and 13.5 points in the PDI scores. Sixty-five percent of the participants had a reduction of at least 3 points on the P-VAS score, while 52% participants showed a decrease of at least 10 points in the PDI score. Significant improvement was observed in the SF-12 physical composite score but not the mental composite score.
CONCLUSIONS: The preliminary findings showed that passive application of low frequency sound wave stimulation therapy through both hands and feet was effective in alleviating pain and improving functional ability in patients with chronic back pain.
Fluid structure interaction simulation of left ventricular flow dynamics under left ventricular assist device support

Ong CW, Chan BT, Lim E, Abu Osman NA, Abed AA, Dokos S, et al.

Annu Int Conf IEEE Eng Med Biol Soc, 2012;2012:6293-6.
PMID: 23367368 DOI: 10.1109/EMBC.2012.6347433

For patient's receiving mechanical circulatory support, malfunction of the left ventricular assist device (LVADs) as well as mal-positioning of the cannula imposes serious threats to their life. It is therefore important to characterize the flow pattern and pressure distribution within the ventricle in the presence of an LVAD. In this paper, we present a 2D axisymmetric fluid structure interaction model of the passive left ventricle (LV) incorporating an LVAD cannula to simulate the effect of the LVAD cannula placement on the vortex dynamics. Results showed that larger recirculation area was formed at the cannula tip with increasing cannula insertion depth, and this is believed to reduce the risk of thrombus formation. Furthermore, we also simulated suction events (collapse of the LV) by closing the inlet. Vortex patterns were significantly altered under this condition, and the greatest LV wall displacement was observed at the part of the myocardium closest to the cannula tip.
Simulation of left ventricle flow dynamics with dilated cardiomyopathy during the filling phase

Chan BT, Ong CW, Lim E, Abu Osman NA, Al Abed A, Lovell NH, et al.

Annu Int Conf IEEE Eng Med Biol Soc, 2012;2012:6289-92.
PMID: 23367367 DOI: 10.1109/EMBC.2012.6347432

Dilated cardiomyopathy (DCM) is a common cardiac disease which leads to the deterioration in cardiac performance. A computational fluid dynamics (CFD) approach can be used to enhance our understanding of the disease, by providing us with a detailed map of the intraventricular flow and pressure distributions. In the present work, effect of ventricular size on the intraventricular flow dynamics and intraventricular pressure gradients (IVPGs) was studied using two different implementation methods, i.e. the geometry-prescribed and the fluid structure interaction (FSI) methods. Results showed that vortex strength and IVPGs are significantly reduced in a dilated heart, leading to an increased risk of thrombus formation and impaired ventricular filling. We suggest FSI method as the ultimate method in studying ventricular dysfunction as it provides additional cardiac disease prognostic factors and more realistic model implementation.
Assessing regional left ventricular thickening dysfunction and dyssynchrony via personalized modeling and 3D wall thickness measurements for acute myocardial infarction

Khalid A, Lim E, Chan BT, Abdul Aziz YF, Chee KH, Yap HJ, et al.

J Magn Reson Imaging, 2019 04;49(4):1006-1019.
PMID: 30211445 DOI: 10.1002/jmri.26302

BACKGROUND: Existing clinical diagnostic and assessment methods could be improved to facilitate early detection and treatment of cardiac dysfunction associated with acute myocardial infarction (AMI) to reduce morbidity and mortality.
PURPOSE: To develop 3D personalized left ventricular (LV) models and thickening assessment framework for assessing regional wall thickening dysfunction and dyssynchrony in AMI patients.
STUDY TYPE: Retrospective study, diagnostic accuracy.
SUBJECTS: Forty-four subjects consisting of 15 healthy subjects and 29 AMI patients.
FIELD STRENGTH/SEQUENCE: 1.5T/steady-state free precession cine MRI scans; LGE MRI scans.
ASSESSMENT: Quantitative thickening measurements across all cardiac phases were correlated and validated against clinical evaluation of infarct transmurality by an experienced cardiac radiologist based on the American Heart Association (AHA) 17-segment model.
STATISTICAL TEST: Nonparametric 2-k related sample-based Kruskal-Wallis test; Mann-Whitney U-test; Pearson's correlation coefficient.
RESULTS: Healthy LV wall segments undergo significant wall thickening (P 50% transmurality) underwent remarkable wall thinning during contraction (thickening index [TI] = 1.46 ± 0.26 mm) as opposed to healthy myocardium (TI = 4.01 ± 1.04 mm). For AMI patients, LV that showed signs of thinning were found to be associated with a significantly higher percentage of dyssynchrony as compared with healthy subjects (dyssynchrony index [DI] = 15.0 ± 5.0% vs. 7.5 ± 2.0%, P
The study of border zone formation in ischemic heart using electro-chemical coupled computational model

Wan Ab Naim WN, Mokhtarudin MJM, Lim E, Chan BT, Ahmad Bakir A, Nik Mohamed NA

Int J Numer Method Biomed Eng, 2020 11;36(11):e3398.
PMID: 32857480 DOI: 10.1002/cnm.3398

Myocardial infarction (MI) is the most common cause of a heart failure, which occurs due to myocardial ischemia leading to left ventricular (LV) remodeling. LV remodeling particularly occurs at the ischemic area and the region surrounds it, known as the border zone. The role of the border zone in initiating LV remodeling process urges the investigation on the correlation between early border zone changes and remodeling outcome. Thus, this study aims to simulate a preliminary conceptual work of the border zone formation and evolution during onset of MI and its effect towards early LV remodeling processes by incorporating the oxygen concentration effect on the electrophysiology of an idealized three-dimensional LV through electro-chemical coupled mathematical model. The simulation result shows that the region of border zone, represented by the distribution of electrical conductivities, keeps expanding over time. Based on this result, the border zone is also proposed to consist of three sub-regions, namely mildly, moderately, and seriously impaired conductivity regions, which each region categorized depending on its electrical conductivities. This division could be used as a biomarker for classification of reversible and irreversible myocardial injury and will help to identify the different risks for the survival of patient. Larger ischemic size and complete occlusion of the coronary artery can be associated with an increased risk of developing irreversible injury, in particular if the reperfusion treatment is delayed. Increased irreversible injury area can be related with cardiovascular events and will further deteriorate the LV function over time.
Effect of intimal flap motion on flow in acute type B aortic dissection by using fluid-structure interaction

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.
Fulltext Sensitivity analysis of left ventricle with dilated cardiomyopathy in fluid structure simulation

Chan BT, Abu Osman NA, Lim E, Chee KH, Abdul Aziz YF, Abed AA, et al.

PLoS One, 2013;8(6):e67097.
PMID: 23825628 DOI: 10.1371/journal.pone.0067097

Dilated cardiomyopathy (DCM) is the most common myocardial disease. It not only leads to systolic dysfunction but also diastolic deficiency. We sought to investigate the effect of idiopathic and ischemic DCM on the intraventricular fluid dynamics and myocardial wall mechanics using a 2D axisymmetrical fluid structure interaction model. In addition, we also studied the individual effect of parameters related to DCM, i.e. peak E-wave velocity, end systolic volume, wall compliance and sphericity index on several important fluid dynamics and myocardial wall mechanics variables during ventricular filling. Intraventricular fluid dynamics and myocardial wall deformation are significantly impaired under DCM conditions, being demonstrated by low vortex intensity, low flow propagation velocity, low intraventricular pressure difference (IVPD) and strain rates, and high-end diastolic pressure and wall stress. Our sensitivity analysis results showed that flow propagation velocity substantially decreases with an increase in wall stiffness, and is relatively independent of preload at low-peak E-wave velocity. Early IVPD is mainly affected by the rate of change of the early filling velocity and end systolic volume which changes the ventriculo:annular ratio. Regional strain rate, on the other hand, is significantly correlated with regional stiffness, and therefore forms a useful indicator for myocardial regional ischemia. The sensitivity analysis results enhance our understanding of the mechanisms leading to clinically observable changes in patients with DCM.
Seroprevalence of toxoplasmosis among migrant workers from different Asian countries working in Malaysia

Chan BT, Amal RN, Hayati MI, Kino H, Anisah N, Norhayati M, et al.

Southeast Asian J. Trop. Med. Public Health, 2008 Jan;39(1):9-13.
PMID: 18567437

A serologic study of Toxoplasma antibodies among 501 foreign migrant workers in Malaysia was conducted in a plantation and detention camp. The highest prevalence rate of 46.2% was among Nepalese workers. Statistical analysis indicated the IgG positivity rate among local residents was significantly higher than the migrants studied (p < 0.05). The IgM positivity rate showed no significant difference between the two groups (p > 0.05). No significant difference in the prevalence rate was noted between the migrants and the local workers when grouped by agricultural and non-agricultural occupations (p > 0.05). The continuous introduction of these infections may influence the epidemiology and further compromise efforts in control and prevention. It is therefore important to monitor of non-notifiable diseases.
Motion corrected LV quantification based on 3D modelling for improved functional assessment in cardiac MRI

Liew YM, McLaughlin RA, Chan BT, Abdul Aziz YF, Chee KH, Ung NM, et al.

Phys Med Biol, 2015 Apr 7;60(7):2715-33.
PMID: 25768708 DOI: 10.1088/0031-9155/60/7/2715

Cine MRI is a clinical reference standard for the quantitative assessment of cardiac function, but reproducibility is confounded by motion artefacts. We explore the feasibility of a motion corrected 3D left ventricle (LV) quantification method, incorporating multislice image registration into the 3D model reconstruction, to improve reproducibility of 3D LV functional quantification. Multi-breath-hold short-axis and radial long-axis images were acquired from 10 patients and 10 healthy subjects. The proposed framework reduced misalignment between slices to subpixel accuracy (2.88 to 1.21 mm), and improved interstudy reproducibility for 5 important clinical functional measures, i.e. end-diastolic volume, end-systolic volume, ejection fraction, myocardial mass and 3D-sphericity index, as reflected in a reduction in the sample size required to detect statistically significant cardiac changes: a reduction of 21-66%. Our investigation on the optimum registration parameters, including both cardiac time frames and number of long-axis (LA) slices, suggested that a single time frame is adequate for motion correction whereas integrating more LA slices can improve registration and model reconstruction accuracy for improved functional quantification especially on datasets with severe motion artefacts.
Specificity and sensitivity of a rapid dipstick test (Brugia Rapid) in the detection of Brugia malayi infection

Rahmah N, Taniawati S, Shenoy RK, Lim BH, Kumaraswami V, Anuar AK, et al.

Trans R Soc Trop Med Hyg, 2002 1 31;95(6):601-4.
PMID: 11816429

A total of 753 serum samples from 6 institutions in 3 countries (Malaysia, Indonesia and India) were used to evaluate an immunochromatographic rapid dipstick test, Brugia Rapid, for diagnosis of Brugia malayi infection. The samples comprised sera from 207 microfilaria-positive individuals and 546 individuals from filaria non-endemic areas. The latter consisted of 70 individuals with soil-transmitted helminth infections, 68 with other helminth infections, 238 with protozoan infections, 12 with bacterial and viral infections and 158 healthy individuals. The dipstick is prepared with a goat anti-mouse antibody control line and a B. malayi recombinant-antigen test line. First, the dipstick is dipped into a well containing diluted patient serum, thus allowing specific anti-filarial antibody in the serum to react with the recombinant antigen. Then the dipstick is placed into an adjacent well containing reconstituted anti-human IgG4-gold. After 10 min, development of 2 red-purplish lines denotes a positive result and one line indicates a negative reaction. The overall results of the evaluation showed 97% sensitivity, 99% specificity, 97% positive predictive value and 99% negative predictive value. Brugia Rapid is thus a promising diagnostic tool for detection of B. malayi infection, and would be especially useful for the brugian filariasis elimination programme.
The study of myocardial ischemia-reperfusion treatment through computational modelling

Wan Ab Naim WN, Mohamed Mokhtarudin MJ, Chan BT, Lim E, Ahmad Bakir A, Nik Mohamed NA

J Theor Biol, 2021 01 21;509:110527.
PMID: 33096094 DOI: 10.1016/j.jtbi.2020.110527

Reperfusion of the blood flow to ischemic myocardium is the standard treatment for patients suffering myocardial infarction. However, the reperfusion itself can also induce myocardial injury, in which the actual mechanism and its risk factors remain unclear. This work aims to study the mechanism of ischemia-reperfusion treatment using a three-dimensional (3D) oxygen diffusion model. An electrical model is then coupled to an oxygen model to identify the possible region of myocardial damage. Our findings show that the value of oxygen exceeds its optimum (>1.0) at the ischemic area during early reperfusion period. This complication was exacerbated in a longer ischemic period. While a longer reperfusion time causes a continuous excessive oxygen supply to the ischemic area throughout the reperfusion time. This work also suggests the use of less than 0.8 of initial oxygen concentration in the reperfusion treatment to prevent undesired upsurge at the early reperfusion period and further myocardial injury. We also found the region at risk for myocardial injury is confined in the ischemic vicinity revealed by its electrical conductivity impairment. Although there is a risk that reperfusion leads to myocardial injury for excessive oxygen accumulation, the reperfusion treatment is helpful in reducing the infarct size.
Left ventricular flow propagation velocity measurement: Is it cast in stone?

Chan BT, Yeoh HK, Liew YM, Aziz YFA, Sridhar GS, Hamilton-Craig C, et al.

Med Biol Eng Comput, 2017 Oct;55(10):1883-1893.
PMID: 28321684 DOI: 10.1007/s11517-017-1639-5

This study aims to investigate the measurement of left ventricular flow propagation velocity, V p, using phase contrast magnetic resonance imaging and to assess the discrepancies resulting from inflow jet direction and individual left ventricular size. Three V p measuring techniques, namely non-adaptive (NA), adaptive positions (AP) and adaptive vectors (AV) method, were suggested and compared. We performed the comparison on nine healthy volunteers and nine post-infarct patients at four measurement positions, respectively, at one-third, one-half, two-thirds and the conventional 4 cm distances from the mitral valve leaflet into the left ventricle. We found that the V p measurement was affected by both the inflow jet direction and measurement positions. Both NA and AP methods overestimated V p, especially in dilated left ventricles, while the AV method showed the strongest correlation with the isovolumic relaxation myocardial strain rate (r = 0.53, p
The role of end-diastolic myocardial fibre stretch on infarct extension

Leong CN, Dokos S, Andriyana A, Liew YM, Chan BT, Abdul Aziz YF, et al.

Int J Numer Method Biomed Eng, 2020 01;36(1):e3291.
PMID: 31799767 DOI: 10.1002/cnm.3291

Myocardial infarct extension, a process involving the enlargement of infarct and border zone, leads to progressive degeneration of left ventricular (LV) function and eventually gives rise to heart failure. Despite carrying a high risk, the causation of infarct extension is still a subject of much speculation. In this study, patient-specific LV models were developed to investigate the correlation between infarct extension and impaired regional mechanics. Subsequently, sensitivity analysis was performed to examine the causal factors responsible for the impaired regional mechanics observed in regions surrounding the infarct and border zone. From our simulations, fibre strain, fibre stress and fibre stress-strain loop (FSSL) were the key biomechanical variables affected in these regions. Among these variables, only FSSL was correlated with infarct extension, as reflected in its work density dissipation (WDD) index value, with high WDD indices recorded at regions with infarct extension. Impaired FSSL is caused by inadequate contraction force generation during the isovolumic contraction and ejection phases. Our further analysis revealed that the inadequacy in contraction force generation is not necessarily due to impaired myocardial intrinsic contractility, but at least in part, due to inadequate muscle fibre stretch at end-diastole, which depresses the ability of myocardium to generate adequate contraction force in the subsequent systole (according to the Frank-Starling law). Moreover, an excessively stiff infarct may cause its neighbouring myocardium to be understretched at end-diastole, subsequently depressing the systolic contractile force of the neighbouring myocardium, which was found to be correlated with infarct extension.
Impact of myocardial infarction on intraventricular vortex and flow energetics assessed using computational simulations

Chan BT, Ahmad Bakir A, Al Abed A, Dokos S, Leong CN, Ooi EH, et al.

Int J Numer Method Biomed Eng, 2019 06;35(6):e3204.
PMID: 30912313 DOI: 10.1002/cnm.3204

Flow energetics have been proposed as early indicators of progressive left ventricular (LV) functional impairment in patients with myocardial infarction (MI), but its correlation with individual MI parameters has not been fully explored. Using electro-fluid-structure interaction LV models, this study investigated the correlation between four MI parameters: infarct size, infarct multiplicity, regional enhancement of contractility at the viable myocardium area (RECVM), and LV mechanical dyssynchrony (LVMD) with intraventricular vortex and flow energetics. In LV with small infarcts, our results showed that infarct appearance amplified the energy dissipation index (DI), where substantial viscous energy loss was observed in areas with high flow velocity and near the infarct-vortex interface. The LV with small multiple infarcts and RECVM showed remarkable DI increment during systole and diastole. In correlation analysis, the systolic kinetic energy fluctuation index (E') was positively related to ejection fraction (EF) (R2 = 0.982) but negatively correlated with diastolic E' (R2 = 0.970). Diastolic E' was inversely correlated with vortex kinetic energy (R2 = 0.960) and vortex depth (R2 = 0.876). We showed an excessive systolic DI could differentiate infarcted LV with normal EF from healthy LV. Strong flow acceleration, LVMD, and vortex-infarct interactions were predominant factors that induced excessive DI in infarcted LVs. Instead of causing undesired flow turbulence, high systolic E' suggested the existence of energetic flow acceleration, while high diastolic E' implied an inefficient diastolic filling. Thus, systolic E' is not a suitable early indicator for progressive LV dysfunction in MI patients, while diastolic E' may be a useful index to indicate diastolic impairment in these patients.
Assessing Complex Left Ventricular Adaptations in Aortic Stenosis Using Personalized 3D + time Cardiac MRI Modeling

Chuah SH, Md Sari NA, Tan LK, Chiam YK, Chan BT, Abdul Aziz YF, et al.

J Cardiovasc Transl Res, 2023 Oct;16(5):1110-1122.
PMID: 37022611 DOI: 10.1007/s12265-023-10375-9

Left ventricular adaptations can be a complex process under the influence of aortic stenosis (AS) and comorbidities. This study proposed and assessed the feasibility of using a motion-corrected personalized 3D + time LV modeling technique to evaluate the adaptive and maladaptive LV response to aid treatment decision-making. A total of 22 AS patients were analyzed and compared against 10 healthy subjects. The 3D + time analysis showed a highly distinct and personalized pattern of remodeling in individual AS patients which is associated with comorbidities and fibrosis. Patients with AS alone showed better wall thickening and synchrony than those comorbid with hypertension. Ischemic heart disease in AS caused impaired wall thickening and synchrony and systolic function. Apart from showing significant correlations to echocardiography and clinical MRI measurements (r: 0.70-0.95; p
Simulating impaired left ventricular-arterial coupling in aging and disease: a systematic review

Ding CCA, Dokos S, Bakir AA, Zamberi NJ, Liew YM, Chan BT, et al.

Biomed Eng Online, 2024 Feb 22;23(1):24.
PMID: 38388416 DOI: 10.1186/s12938-024-01206-2

Aortic stenosis, hypertension, and left ventricular hypertrophy often coexist in the elderly, causing a detrimental mismatch in coupling between the heart and vasculature known as ventricular-vascular (VA) coupling. Impaired left VA coupling, a critical aspect of cardiovascular dysfunction in aging and disease, poses significant challenges for optimal cardiovascular performance. This systematic review aims to assess the impact of simulating and studying this coupling through computational models. By conducting a comprehensive analysis of 34 relevant articles obtained from esteemed databases such as Web of Science, Scopus, and PubMed until July 14, 2022, we explore various modeling techniques and simulation approaches employed to unravel the complex mechanisms underlying this impairment. Our review highlights the essential role of computational models in providing detailed insights beyond clinical observations, enabling a deeper understanding of the cardiovascular system. By elucidating the existing models of the heart (3D, 2D, and 0D), cardiac valves, and blood vessels (3D, 1D, and 0D), as well as discussing mechanical boundary conditions, model parameterization and validation, coupling approaches, computer resources and diverse applications, we establish a comprehensive overview of the field. The descriptions as well as the pros and cons on the choices of different dimensionality in heart, valve, and circulation are provided. Crucially, we emphasize the significance of evaluating heart-vessel interaction in pathological conditions and propose future research directions, such as the development of fully coupled personalized multidimensional models, integration of deep learning techniques, and comprehensive assessment of confounding effects on biomarkers.
Fulltext Comparison of diametric and volumetric changes in Stanford type B aortic dissection patients in assessing aortic remodeling post-stent graft treatment

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.

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