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Arefin NM, Good BC. Investigation of cardiopulmonary bypass parameters on embolus transport in a patient-specific aorta. Biomech Model Mechanobiol 2024; 23:1765-1780. [PMID: 38884891 DOI: 10.1007/s10237-024-01867-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 06/05/2024] [Indexed: 06/18/2024]
Abstract
Neurological complexities resulting from surgery requiring cardiopulmonary bypass (CPB) remain a major concern, encompassing a spectrum of complications including thromboembolic stroke and various cognitive impairments. Surgical manipulation during CPB is considered the primary cause of these neurological complications. This study addresses the overall lack of knowledge concerning CPB hemodynamics within the aorta, employing a combined experimental-computational modeling approach, featuring computational fluid dynamics simulations validated with an in vitro CPB flow loop under steady conditions. Parametric studies were systematically performed, varying parameters associated with CPB techniques (pump flow rate and hemodiluted blood viscosity) and properties related to formed emboli (size and density). This represents the first comprehensive investigation into the individual and combined effects of these factors. Our findings reveal critical insights into the operating conditions of CPB, indicating a positive correlation between pump flow rate and emboli transport into the aortic branches, potentially increasing the risk of stroke. It was also found that larger emboli were more often transported into the aortic branches at higher pump flow rates, while smaller emboli preferred lower flow rates. Further, as blood is commonly diluted during CPB to decrease its viscosity, more emboli were found to enter the aortic branches with greater hemodilution. The combined effects of these parameters are captured using the non-dimensional Stokes number, which was found to positively correlate with emboli transport into the aortic branches. These findings contribute to our understanding of embolic stroke risk factors during CPB and shed light on the complex interplay between CPB parameters.
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Affiliation(s)
- Nafis M Arefin
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, TN, USA
| | - Bryan C Good
- Department of Mechanical, Aerospace, and Biomedical Engineering, University of Tennessee, Knoxville, TN, USA.
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Velasco Gonzalez A, Sauerland C, Görlich D, Ortega-Quintanilla J, Jeibmann A, Faldum A, Paulus W, Heindel W, Buerke B. Exploring the relationship between embolic acute stroke distribution and supra-aortic vessel patency: key findings from an in vitro model study. Stroke Vasc Neurol 2024:svn-2023-003024. [PMID: 38782495 DOI: 10.1136/svn-2023-003024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 04/12/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND We investigated differences in intracranial embolus distribution through communicating arteries in relation to supra-aortic vessel (SAV) patency. METHODS For this experimental analysis, we created a silicone model of the extracranial and intracranial circulations using a blood-mimicking fluid under physiological pulsatile flow. We examined the sequence of embolus lodgment on injecting 104 frangible clot analogues (406 emboli) through the right internal carotid artery (CA) as SAV patency changed: (a) all SAV patent (baseline), (b) emboli from a CA occlusion, (c) emboli contralateral to a CA occlusion and (d) occlusion of the posterior circulation. The statistical analysis included a descriptive analysis of thrombi location after occlusion (absolute and relative frequencies). Sequences of occlusions were displayed in Sankey flow charts for the four SAV conditions. Associations between SAV conditions and occlusion location were tested by Fisher's exact test. Two-sided p values were compared with a significance level of 0.05. RESULTS The total number of emboli was 406 (median fragments/clot: 4 (IQR: 3-5)). Embolus lodgment was dependent on SAV patency (p<0.0001). In all scenarios, embolism lodging in the anterior cerebral artery (ACA) occurred after a previous middle cerebral artery (MCA) embolism (MCA first lodge: 96%, 100/104). The rate of ipsilateral ACA embolism was 28.9% (28/97) at baseline, decreasing significantly when emboli originated from an occluded CA (16%, 14/88). There were more bihemispheric embolisations in cases of contralateral CA occlusion (37%, 45/122), with bilateral ACA embolisms preceding contralateral MCA embolism in 56% of cases (14/25 opposite MCA and ACA embolism). CONCLUSIONS All emboli in the ACA occurred after a previous ipsilateral MCA embolism. Bihemispheric embolisms were rare, except when there was a coexisting occlusion in either CA, particularly in cases of a contralateral CA occlusion.
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Affiliation(s)
- Aglae Velasco Gonzalez
- Clinic for Radiology, Neuroradiology, University of Münster and University Hospital of Münster, Münster, Germany
| | - Cristina Sauerland
- Institute of Biostatistics and Clinical Research, University of Münster, Munster, Germany
| | - Dennis Görlich
- Institute of Biostatistics and Clinical Research, University of Münster, Munster, Germany
| | | | - Astrid Jeibmann
- Institute of Neuropathology, University of Münster, Munster, Germany
| | - Andreas Faldum
- Institute of Biostatistics and Clinical Research, University of Münster, Munster, Germany
| | - Werner Paulus
- Institute of Neuropathology, University of Münster, Munster, Germany
| | - Walter Heindel
- Clinic for Radiology, Neuroradiology, University of Münster and University Hospital of Münster, Münster, Germany
| | - Boris Buerke
- Clinic for Radiology, Neuroradiology, University of Münster and University Hospital of Münster, Münster, Germany
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Khamooshi M, Wickramarachchi A, Byrne T, Seman M, Fletcher DF, Burrell A, Gregory SD. Blood flow and emboli transport patterns during venoarterial extracorporeal membrane oxygenation: A computational fluid dynamics study. Comput Biol Med 2024; 172:108263. [PMID: 38489988 DOI: 10.1016/j.compbiomed.2024.108263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/15/2024] [Accepted: 03/06/2024] [Indexed: 03/17/2024]
Abstract
PROBLEM Despite advances in Venoarterial Extracorporeal Membrane Oxygenation (VA-ECMO), a significant mortality rate persists due to complications. The non-physiological blood flow dynamics of VA-ECMO may lead to neurological complications and organ ischemia. Continuous retrograde high-flow oxygenated blood enters through a return cannula placed in the femoral artery which opposes the pulsatile deoxygenated blood ejected by the left ventricle (LV), which impacts upper body oxygenation and subsequent hyperoxemia. The complications underscore the critical need to comprehend the impact of VA-ECMO support level and return cannula size, as mortality remains a significant concern. AIM The aim of this study is to predict and provide insights into the complications associated with VA-ECMO using computational fluid dynamics (CFD) simulations. These complications will be assessed by characterising blood flow and emboli transport patterns through a comprehensive analysis of the influence of VA-ECMO support levels and arterial return cannula sizes. METHODS Patient-specific 3D aortic and major branch models, derived from a male patient's CT scan during VA-ECMO undergoing respiratory dysfunction, were analyzed using CFD. The investigation employed species transport and discrete particle tracking models to study ECMO blood (oxygenated) mixing with LV blood (deoxygenated) and to trace emboli transport patterns from potential sources (circuit, LV, and aorta wall). Two cannula sizes (15 Fr and 19 Fr) were tested alongside varying ECMO pump flow rates (50%, 70%, and 90% of the total cardiac output). RESULTS Cannula size did not significantly affect oxygen transport. At 90% VA-ECMO support, all arteries distal to the aortic arch achieved 100% oxygen saturation. As support level decreased, oxygen transport to the upper body also decreased to a minimum saturation of 73%. Emboli transport varied substantially between emboli origin and VAECMO support level, with the highest risk of cerebral emboli coming from the LV with a 15 Fr cannula at 90% support. CONCLUSION Arterial return cannula sizing minimally impacted blood oxygen distribution; however, it did influence the distribution of emboli released from the circuit and aortic wall. Notably, it was the support level alone that significantly affected the mixing zone of VA-ECMO and cardiac blood, subsequently influencing the risk of embolization of the cardiogenic source and oxygenation levels across various arterial branches.
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Affiliation(s)
- Mehrdad Khamooshi
- Cardio-Respiratory Engineering and Technology Laboratory (CREATElab), Department of Mechanical and Aerospace Engineering, Monash University, Wellington Road, Clayton, 3800, Victoria, Australia.
| | - Avishka Wickramarachchi
- Cardio-Respiratory Engineering and Technology Laboratory (CREATElab), Department of Mechanical and Aerospace Engineering, Monash University, Wellington Road, Clayton, 3800, Victoria, Australia.
| | - Tim Byrne
- Intensive Care Unit, Alfred Hospital, 89 Commercial Road, Melbourne, 3004, Victoria, Australia.
| | - Michael Seman
- Cardio-Respiratory Engineering and Technology Laboratory (CREATElab), Department of Mechanical and Aerospace Engineering, Monash University, Wellington Road, Clayton, 3800, Victoria, Australia.
| | - David F Fletcher
- School of Chemical and Biomolecular Engineering, The University of Sydney, Darlington, 2006, New South Wales, Australia.
| | - Aidan Burrell
- Intensive Care Unit, Alfred Hospital, 89 Commercial Road, Melbourne, 3004, Victoria, Australia.
| | - Shaun D Gregory
- Cardio-Respiratory Engineering and Technology Laboratory (CREATElab), Department of Mechanical and Aerospace Engineering, Monash University, Wellington Road, Clayton, 3800, Victoria, Australia.
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Morris L, Tierney P, Hynes N, Sultan S. An in vitro Assessment of the Haemodynamic Features Occurring Within the True and False Lumens Separated by a Dissection Flap for a Patient-Specific Type B Aortic Dissection. Front Cardiovasc Med 2022; 9:797829. [PMID: 35369331 PMCID: PMC8968342 DOI: 10.3389/fcvm.2022.797829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 02/15/2022] [Indexed: 11/14/2022] Open
Abstract
One of the highest mortality rates of cardiovascular diseases is aortic dissections with challenging treatment options. Currently, less study has been conducted in developing in vitro patient-specific Type B aortic dissection models, which mimic physiological flow conditions along the true and false lumens separated by a dissection flap with multiple entry and exit tears. A patient-specific Stanford Type B aortic dissection scan was replicated by an in-house manufactured automatic injection moulding system and a novel modelling technique for creating the ascending aorta, aortic arch, and descending aorta incorporating arterial branching, the true/false lumens, and dissection flap with entry and exit intimal tears. The physiological flowrates and pressure values were monitored, which identified jet stream fluid flows entering and exiting the dissection tears. Pressure in the aorta’s true lumen region was controlled at 125/85 mmHg for systolic and diastolic values. Pressure values were obtained in eight sections along the false lumen using a pressure transducer. The true lumen systolic pressure varied from 122 to 128 mmHg along the length. Flow patterns were monitored by ultrasound along 12 sections. Detailed images obtained from the ultrasound transducer probe showed varied flow patterns with one or multiple jet steam vortices along the aorta model. The dissection flap movement was assessed at four sections of the patient-specific aorta model. The displacement values of the flap varied from 0.5 to 3 mm along the model. This model provides a unique insight into aortic dissection flow patterns and pressure distributions. This dissection phantom model can be used to assess various treatment options based on the surgical, endovascular, or hybrid techniques.
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Affiliation(s)
- Liam Morris
- Galway-Mayo Institute of Technology, Galway, Ireland
- Galway Medical Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
- Medical and Engineering Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
- Lero – Science Foundation Ireland Research Centre for Software, Galway-Mayo Institute of Technology, Galway, Ireland
- *Correspondence: Liam Morris,
| | - Paul Tierney
- Galway Medical Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
- Medical and Engineering Technology Centre, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
| | - Niamh Hynes
- CÚRAM, National University of Ireland, Galway, Ireland
| | - Sherif Sultan
- Western Vascular Institute, Department of Vascular and Endovascular Surgery, University College Hospital Galway, Galway, Ireland
- Department of Vascular and Endovascular Surgery, Galway Clinic, Royal College of Surgeons in Ireland, Doughiska, Ireland
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Lyashevska O, Malone F, MacCarthy E, Fiehler J, Buhk JH, Morris L. Class imbalance in gradient boosting classification algorithms: Application to experimental stroke data. Stat Methods Med Res 2020; 30:916-925. [PMID: 33356965 DOI: 10.1177/0962280220980484] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Imbalance between positive and negative outcomes, a so-called class imbalance, is a problem generally found in medical data. Imbalanced data hinder the performance of conventional classification methods which aim to improve the overall accuracy of the model without accounting for uneven distribution of the classes. To rectify this, the data can be resampled by oversampling the positive (minority) class until the classes are approximately equally represented. After that, a prediction model such as gradient boosting algorithm can be fitted with greater confidence. This classification method allows for non-linear relationships and deep interactive effects while focusing on difficult areas by iterative shifting towards problematic observations. In this study, we demonstrate application of these methods to medical data and develop a practical framework for evaluation of features contributing into the probability of stroke.
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Affiliation(s)
- Olga Lyashevska
- Enterprise Ireland Medical and Engineering Technologies Gateway, GMIT, Galway, Ireland.,Marine and Freshwater Research Centre, GMIT, Galway, Ireland
| | - Fiona Malone
- Enterprise Ireland Medical and Engineering Technologies Gateway, GMIT, Galway, Ireland
| | - Eugene MacCarthy
- Enterprise Ireland Medical and Engineering Technologies Gateway, GMIT, Galway, Ireland
| | - Jens Fiehler
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jan-Hendrik Buhk
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Liam Morris
- Enterprise Ireland Medical and Engineering Technologies Gateway, GMIT, Galway, Ireland
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Malone F, McCarthy E, Delassus P, Buhk JH, Fiehler J, Morris L. An in vitro assessment of atrial fibrillation flow types on cardiogenic emboli trajectory paths. Proc Inst Mech Eng H 2020; 234:1421-1431. [DOI: 10.1177/0954411920946873] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Atrial fibrillation is the most significant contributor to thrombus formation within the heart and is responsible for 45% of all cardio embolic strokes, which account for approximately 15% of acute ischemic strokes cases worldwide. Atrial fibrillation can result in a reduction of normal cardiac output and cycle length of up to 30% and 40%, respectively. A total of 240 embolus analogues were released into a thin-walled, patient-specific aortic arch under normal (60 embolus analogues) and varying atrial fibrillation (180 embolus analogues) pulsatile flow conditions. Under healthy flow conditions (n = 60), the embolus analogues tended to follow the flow rate split through each outlet vessel. There was an increase in clot trajectories along the common carotid arteries under atrial fibrillation flow conditions. A shorter pulse period (0.3 s) displayed the highest percentage of clots travelling to the brain (24%), with a greater percentage of clots travelling through the left common carotid artery (17%). This study provides an experimental insight into the effect varying cardiac output and cycle length can have on the trajectory of a cardiac source blood clots travelling to the cerebral vasculature and possibly causing a stroke.
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Affiliation(s)
- Fiona Malone
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
| | - Eugene McCarthy
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
| | - Patrick Delassus
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
| | - Jan-Hendrick Buhk
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Jens Fiehler
- Department of Diagnostic and Interventional Neuroradiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Liam Morris
- GMedTech, Department of Mechanical and Industrial Engineering, Galway-Mayo Institute of Technology, Galway, Ireland
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