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Kharche SR, Dobrzynski H, Goldman D. Editorial: Vascular Disease Multi-Scale Multi-Physics Modeling and Experimental Data. Front Physiol 2022; 13:865905. [PMID: 35370803 PMCID: PMC8970683 DOI: 10.3389/fphys.2022.865905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 02/21/2022] [Indexed: 11/24/2022] Open
Affiliation(s)
- Sanjay R. Kharche
- Department of Medical Biophysics, Western University, London, ON, Canada
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
- Kidney Clinical Research Unit, Lawson Health Research Institute, London, ON, Canada
- *Correspondence: Sanjay R. Kharche
| | - Halina Dobrzynski
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
- Department of Anatomy, Jagiellonian University Medical College, Kraków, Poland
| | - Daniel Goldman
- Department of Medical Biophysics, Western University, London, ON, Canada
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Electro-anatomical computational cardiology in humans and experimental animal models. TRANSLATIONAL RESEARCH IN ANATOMY 2022. [DOI: 10.1016/j.tria.2022.100162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app12010307] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Background: We developed a hemodynamic mathematical model of human circulation coupled to a virtual hemodialyzer. The model was used to explore mechanisms underlying our clinical observations involving hemodialysis. Methods: The model consists of whole body human circulation, baroreflex feedback control, and a hemodialyzer. Four model populations encompassing baseline, dialysed, therapeutic hypothermia treated, and simultaneous dialysed with hypothermia were generated. In all populations atrial fibrillation and renal failure as co-morbidities, and exercise as a treatment were simulated. Clinically relevant measurables were used to quantify the effects of each in silico experiment. Sensitivity analysis was used to uncover the most relevant parameters. Results: Relative to baseline, the modelled dialysis increased the population mean diastolic blood pressure by 5%, large vessel wall shear stress by 6%, and heart rate by 20%. Therapeutic hypothermia increased systolic blood pressure by 3%, reduced large vessel shear stress by 15%, and did not affect heart rate. Therapeutic hypothermia reduced wall shear stress by 15% in the aorta and 6% in the kidneys, suggesting a potential anti-inflammatory benefit. Therapeutic hypothermia reduced cardiac output under atrial fibrillation by 12% and under renal failure by 20%. Therapeutic hypothermia and exercise did not affect dialyser function, but increased water removal by approximately 40%. Conclusions: This study illuminates some mechanisms of the action of therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.
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Kharche SR, Lemoine S, Tamasi T, Hur L, So A, McIntyre CW. Therapeutic Hypothermia Reduces Peritoneal Dialysis Induced Myocardial Blood Flow Heterogeneity and Arrhythmia. Front Med (Lausanne) 2021; 8:700824. [PMID: 34395480 PMCID: PMC8362929 DOI: 10.3389/fmed.2021.700824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 06/30/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Moderate therapeutic hypothermia (TH) is a well-recognized cardio-protective strategy. The instillation of fluid into the peritoneum provides an opportunity to deliver moderate hypothermia as primary prevention against cardiovascular events. We aimed to to investigate both cardiac perfusion consequences (overall blood flow and detailed assessment of perfusion heterogeneity) and subsequently simulate the associated arrhythmic risk for patients undergoing peritoneal dialysis (PD) induced TH. Methods: Patients underwent high resolution myocardial perfusion scanning using high resolution 256 slice CT scanning, at rest and with adenosine stress. The first visit using the patient's usual PD regimen, on the second visit the same regime was utilized but with cooled peritoneal dialysate at 32°C. Myocardial blood flow (MBF) was quantified from generated perfusion maps, reconstructed in 3D. MBF heterogeneity was assessed by fractal dimension (FD) measurement on the 3D left ventricular reconstruction. Arrhythmogenicity was quantified from a sophisticated computational simulation using a multi-scale human 3D ventricle wedge electrophysiological computational model. Results: We studied 7 PD patients, mean age of 60 ± 7 and mean vintage dialysis of 23.6 ± 17.6 months. There were no significant different in overall segmental MBF between normothermic condition (NT) and TH. MBF heterogeneity was significantly decreased (-14%, p = 0.03) at rest and after stress (-14%, p = 0.03) when cooling was applied. Computational simulation showed that TH allowed a normalization of action potential, QT duration and T wave. Conclusion: TH-PD results in moderate hypothermia leading to a reduction in perfusion heterogeneity and simulated risk of non-terminating malignant ventricular arrhythmias.
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Affiliation(s)
- Sanjay R Kharche
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada.,Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| | - Sandrine Lemoine
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Tanya Tamasi
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Lisa Hur
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada
| | - Aaron So
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada.,Imaging Program, Lawson Health Research Institute, London, ON, Canada
| | - Christopher W McIntyre
- Kidney Clinical Research Unit, Lawson's Health Research Institute, Victoria Hospital, London, ON, Canada.,Department of Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
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Li P, Pan Q, Jiang S, Yan M, Yan J, Ning G. Development of Novel Fractal Method for Characterizing the Distribution of Blood Flow in Multi-Scale Vascular Tree. Front Physiol 2021; 12:711247. [PMID: 34393827 PMCID: PMC8358817 DOI: 10.3389/fphys.2021.711247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 07/09/2021] [Indexed: 11/13/2022] Open
Abstract
Blood perfusion is an important index for the function of the cardiovascular system and it can be indicated by the blood flow distribution in the vascular tree. As the blood flow in a vascular tree varies in a large range of scales and fractal analysis owns the ability to describe multi-scale properties, it is reasonable to apply fractal analysis to depict the blood flow distribution. The objective of this study is to establish fractal methods for analyzing the blood flow distribution which can be applied to real vascular trees. For this purpose, the modified methods in fractal geometry were applied and a special strategy was raised to make sure that these methods are applicable to an arbitrary vascular tree. The validation of the proposed methods on real arterial trees verified the ability of the produced parameters (fractal dimension and multifractal spectrum) in distinguishing the blood flow distribution under different physiological states. Furthermore, the physiological significance of the fractal parameters was investigated in two situations. For the first situation, the vascular tree was set as a perfect binary tree and the blood flow distribution was adjusted by the split ratio. As the split ratio of the vascular tree decreases, the fractal dimension decreases and the multifractal spectrum expands. The results indicate that both fractal parameters can quantify the degree of blood flow heterogeneity. While for the second situation, artificial vascular trees with different structures were constructed and the hemodynamics in these vascular trees was simulated. The results suggest that both the vascular structure and the blood flow distribution affect the fractal parameters for blood flow. The fractal dimension declares the integrated information about the heterogeneity of vascular structure and blood flow distribution. In contrast, the multifractal spectrum identifies the heterogeneity features in blood flow distribution or vascular structure by its width and height. The results verified that the proposed methods are capable of depicting the multi-scale features of the blood flow distribution in the vascular tree and further are potential for investigating vascular physiology.
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Affiliation(s)
- Peilun Li
- Department of Biomedical Engineering, Zhejiang University, Hangzhou, China
| | - Qing Pan
- College of Information Engineering, Zhejiang University of Technology, Hangzhou, China
| | - Sheng Jiang
- Department of Biomedical Engineering, Zhejiang University, Hangzhou, China
| | - Molei Yan
- Department of Intensive Care Medicine, Zhejiang Hospital, Hangzhou, China
| | - Jing Yan
- Department of Intensive Care Medicine, Zhejiang Hospital, Hangzhou, China
| | - Gangmin Ning
- Department of Biomedical Engineering, Zhejiang University, Hangzhou, China
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Lai AC, Bienstock SW, Sharma R, Skorecki K, Beerkens F, Samtani R, Coyle A, Kim T, Baber U, Camaj A, Power D, Fuster V, Goldman ME. A Personalized Approach to Chronic Kidney Disease and Cardiovascular Disease: JACC Review Topic of the Week. J Am Coll Cardiol 2021; 77:1470-1479. [PMID: 33736830 DOI: 10.1016/j.jacc.2021.01.028] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/30/2020] [Accepted: 01/04/2021] [Indexed: 01/11/2023]
Abstract
Cardiovascular disease is the most common cause of death in patients with end-stage renal disease (ESRD). The initiation of dialysis for treatment of ESRD exacerbates chronic electrolyte and hemodynamic perturbations. Rapid large shifts in effective intravascular volume and electrolyte concentrations ultimately lead to subendocardial ischemia, increased left ventricular wall mass, and diastolic dysfunction, and can precipitate serious arrhythmias through a complex pathophysiological process. These factors, unique to advanced kidney disease and its treatment, increase the overall incidence of acute coronary syndrome and sudden cardiac death. To date, risk prediction models largely fail to incorporate the observed cardiovascular mortality in the CKD population; however, multimodality imaging may provide an additional prognostication and risk stratification. This comprehensive review discusses the cardiovascular risks associated with hemodialysis, and explores the pathophysiology and the novel utilization of multimodality imaging in CKD to promote a personalized approach for these patients with implications for future research.
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Affiliation(s)
- Ashton C Lai
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | | | - Raman Sharma
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Karl Skorecki
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Frans Beerkens
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Rajeev Samtani
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Andrew Coyle
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Tonia Kim
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Usman Baber
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Anton Camaj
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - David Power
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA
| | - Valentin Fuster
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA; Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Martin E Goldman
- Icahn School of Medicine at Mount Sinai Hospital, New York, New York, USA.
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Current and novel imaging techniques to evaluate myocardial dysfunction during hemodialysis. Curr Opin Nephrol Hypertens 2020; 29:555-563. [PMID: 33009128 DOI: 10.1097/mnh.0000000000000645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Patients on hemodialysis have significantly higher rates of cardiovascular mortality resulting from a multitude of myocardial dysfunctions. Current imaging modalities allow independent assessment of cardiac morphology, contractile function, coronary arteries and cardiac perfusion. Techniques such as cardiac computed tomography (CT) imaging have been available for some time, but have not yet had widespread adoption because of technical limitations related to cardiac motion, radiation exposure and safety of contrast agents in kidney disease. RECENT FINDINGS Novel dynamic contrast-enhanced (DCE) CT imaging can be used to acquire high-resolution cardiac images, which simultaneously allow the assessment of coronary arteries and the quantitative measurement of myocardial perfusion. The advancement of recent CT scanners and cardiac protocols have allowed noninvasive imaging of the whole heart in a single imaging session with minimal cardiac motion artefact and exposure to radiation. SUMMARY DCE-CT imaging in clinical practice would allow comprehensive evaluation of the structure, function, and hemodynamics of the heart in a short, well tolerated scanning session. It is an imaging tool enabling the study of myocardial dysfunction in dialysis patients, who have greater cardiovascular risk than nonrenal cardiovascular disease populations, both at rest and under cardiac stress associated with hemodialysis itself.
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Kharche SR, Desai K, McIntyre CW. Elucidating the relationship between arrhythmia and ischemic heterogeneity: an in silico study. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2020; 2020:2434-2437. [PMID: 33018498 DOI: 10.1109/embc44109.2020.9176737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Dialysis causes blood flow defects in the heart that may augment electrophysiological heterogeneity in the form of increased number of ischemic zones in the human left ventricle. We computationally tested whether a larger number of ischemic zones aggravate arrhythmia using a 2D electrophysiological model of the human ventricle.A human ventricle cardiomyocyte model capable of simulating ischemic action potentials was adapted in this study. The cell model was incorporated into a spatial 2D model consisting of known number of ischemic zones. Inter-cellular gap junction coupling within ischemic zones was reduced to simulate slow conduction. Arrhythmia severity was assessed by inducing a re-entry, and quantifying the ensuing breakup and tissue pacing rates.Ischemia elevated the isolated cardiomyocyte's resting potential and reduced its action potential duration. In the absence of ischemic zones, the propensity in the 2D model to induce multiple re-entrant waves was low. The inclusion of ischemic zones provided the substrate for initiation of re-entrant waves leading to fibrillation. Dominant frequency, which measured the highest rate of pacing in the tissue, increased drastically with the inclusion of multiple ischemic zones. Re-entrant wave tip maximum numbers increased from 1 tip (no ischemic zone) to 34 tips when a large number (20) of ischemic zones were included. Computational limiting factors of our platform were identified using software profiling.Clinical significance. Dialysis may promote deleterious arrhythmias by increasing tissue level action potential dispersion.
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Altamirano-Diaz L, Kassay AD, Serajelahi B, McIntyre CW, Filler G, Kharche SR. Arterial Hypertension and Unusual Ascending Aortic Dilatation in a Neonate With Acute Kidney Injury: Mechanistic Computer Modeling. Front Physiol 2019; 10:1391. [PMID: 31780955 PMCID: PMC6856675 DOI: 10.3389/fphys.2019.01391] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 10/25/2019] [Indexed: 01/23/2023] Open
Abstract
Background Neonatal asphyxia caused kidney injury and severe hypertension in a newborn. An unusually dilatated ascending aorta developed. Dialysis and pharmacological treatment led to partial recovery of the ascending aortic diameters. It was hypothesized that the aortic dilatation may be associated with aortic stiffening, peripheral resistance, and cardiovascular changes. Mathematical modeling was used to better understand the potential causes of the hypertension, and to confirm our clinical treatment within the confines of the model's capabilities. Methods The patient's systolic arterial blood pressure showed hypertension. Echocardiographic exams showed ascending aorta dilatation during hypertension, which partially normalized upon antihypertensive treatment. To explore the underlying mechanisms of the aortic dilatation and hypertension, an existing lumped parameter hemodynamics model was deployed. Hypertension was simulated using realistic literature informed parameter values. It was also simulated using large parameter perturbations to demonstrate effects. Simulations were designed to permit examination of causal mechanisms. The hypertension inducing effects of aortic stiffnesses, vascular resistances, and cardiac hypertrophy on blood flow and pressure were simulated. Sensitivity analysis was used to stratify causes. Results In agreement with our clinical diagnosis, the model showed that an increase of aortic stiffness followed by augmentation of peripheral resistance are the prime causes of realistic hypertension. Increased left ventricular elastance may also cause hypertension. Ascending aortic pressure and flow increased in the simultaneous presence of left ventricle hypertrophy and augmented small vessel resistance, which indicate a plausible condition for ascending aorta dilatation. In case of realistic hypertension, sensitivity analysis showed that the treatment of both the large vessel stiffness and small vessel resistance are more important in comparison to cardiac hypertrophy. Conclusion and Discussion Large vessel stiffness was found to be the prime factor in arterial hypertension, which confirmed the clinical treatment. Treatment of cardiac hypertrophy appears to provide significant benefit but may be secondary to treatment of large vessel stiffness. The quantitative grading of pathophysiological mechanisms provided by the modeling may contribute to treatment recommendations. The model was limited due to a lack of data suitable to permit model identification.
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Affiliation(s)
- Luis Altamirano-Diaz
- Department of Paediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Children's Health Research Institute, London, ON, Canada.,Paediatric Cardiopulmonary Research Laboratory, LHSC, London, ON, Canada
| | | | - Baran Serajelahi
- Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Christopher W McIntyre
- Department of Paediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - Guido Filler
- Department of Paediatrics, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Children's Health Research Institute, London, ON, Canada.,Lawson Health Research Institute, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
| | - Sanjay R Kharche
- Lawson Health Research Institute, London, ON, Canada.,Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada.,Department of Medical Biophysics, Western University, London, ON, Canada
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