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Park CM, Hughes AD, Henein MY, Khir AW. Mechanisms of Aortic Flow Deceleration and the Effect of Wave Reflection on Left Ventricular Function. Front Physiol 2020; 11:578701. [PMID: 33250774 PMCID: PMC7676911 DOI: 10.3389/fphys.2020.578701] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/29/2020] [Indexed: 11/24/2022] Open
Abstract
Increased wave reflection is an independent predictor of cardiovascular events, possibly due to effects on left ventricular (LV) function. We investigated the relationship between reflected waves in early systole, the forward decompression wave in mid-late systole and LV mechanical behavior. Invasively acquired ascending aortic velocity, pressure, and LV long and minor axes’ dimensions were measured simultaneously in 11 anesthetized dogs during both control conditions and aortic occlusion to cause additional early wave reflection. Wave intensity analysis (WIA) was used to identify the arrival of the reflected wave and the onset of a forward decompression wave in mid-late systole. The arrival time of the reflected wave coincided with the time when minor axis shortening began to decline from its peak, even during aortic occlusion when this time is 12 ms earlier. The initial decline in long axis shortening corresponded to the time of the peak of the reflected wave. The forward decompression wave was consistently observed to have a slow and then rapid phase. The slow phase onset coincided with time of maximum shortening velocity of the long axis. The onset of the later larger rapid phase consistently coincided with an increased rate of deceleration of both axes during late systole. Forward decompression waves are generated by the LV when the long axis shortening velocity falls. Reflected wave arrival has a detrimental effect on LV function, particularly the minor axis. These observations lend support to suggestions that therapies directed toward reducing wave reflection may be of value in hypertension and cardiovascular disease.
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Affiliation(s)
- Chloe M Park
- Brunel Institute for Bioengineering, Brunel University London, London, United Kingdom.,Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Alun D Hughes
- Institute of Cardiovascular Science, University College London, London, United Kingdom
| | - Michael Y Henein
- Brunel Institute for Bioengineering, Brunel University London, London, United Kingdom.,Umea Heart Centre, Umea University Hospital, Umea, Sweden
| | - Ashraf W Khir
- Brunel Institute for Bioengineering, Brunel University London, London, United Kingdom
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Kurakova L, Misak A, Tomasova L, Cacanyiova S, Berenyiova A, Ondriasova E, Balis P, Grman M, Ondrias K. Mathematical relationships of patterns of 35 rat haemodynamic parameters for conditions of hypertension resulting from decreased nitric oxide bioavailability. Exp Physiol 2020; 105:312-334. [PMID: 31769908 DOI: 10.1113/ep088148] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
NEW FINDINGS What is the central question of this study? Can the cross-relationship between 35 rat arterial pulse waveform (APW) parameters be described by known mathematical functions and can mathematical parameters be obtained for conditions in a model of hypertension resulting from decreased NO bioavailability? What is the main finding and its importance? Mathematical functions and their parameters were obtained that approximate the cross-relationships of 35 APW parameters to systolic blood pressure and to the augmentation index in conditions of decreased NO bioavailability. The results enable APW parameters to be assigned to decreased NO bioavailability, which may have predictive or diagnostic value. ABSTRACT Information obtained from the arterial pulse waveform (APW) using haemodynamic parameters (HPs) is useful for characterization of the cardiovascular system in particular (patho)physiological conditions. Our goal was to find out whether the relationships between rat HPs could be described by simple mathematical functions and to find mathematical parameters for conditions of high blood pressure (BP) resulting from decreased NO bioavailability. The right jugular vein of anaesthetized Wistar rats was cannulated for i.v. administration of Nω -nitro-l-arginine methyl ester (l-NAME). The left common carotid artery was cannulated to detect the APW. From 10 points on the rat APW we defined 35 HPs (some were known already) and found 595 cross-relationships between HPs showing unique patterns for particular cardiovascular conditions. Here we show parallel time-dependent changes of 35 HPs and some of their cross-relationships in condition of high BP induced by l-NAME. We found that most of the time-dependent changes of 35 HPs and their relationships were very well fitted by simple mathematical functions, e.g. a linear function, exponential growth, exponential decay or exponential rise to maximum. The results may enable the mathematical functions to be assigned for decreased NO bioavailability, which may have predictive or diagnostic value for conditions of high BP. Using this approach, it may be possible to find unique cross-relationship patterns of HPs and mathematical functions between HPs for different cardiovascular (patho)physiological or drug-modulating conditions. This knowledge can be used in studying the molecular mechanisms of particular (patho)physiological conditions or drug actions and may have predictive or diagnostic value.
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Affiliation(s)
- Lucia Kurakova
- Faculty of Pharmacy, Comenius University, Bratislava, Slovak Republic.,Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Anton Misak
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Lenka Tomasova
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Sona Cacanyiova
- Institute of Normal and Pathological Physiology, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Andrea Berenyiova
- Institute of Normal and Pathological Physiology, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Elena Ondriasova
- Faculty of Pharmacy, Comenius University, Bratislava, Slovak Republic
| | - Peter Balis
- Institute of Normal and Pathological Physiology, Centre of Experimental Medicine, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Marian Grman
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Karol Ondrias
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
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Misak A, Kristek F, Tomasova L, Grman M, Ondriasova E, Krizanova O, Ondrias K. Mathematical relationships and their consequences between rat pulse waveform parameters and blood pressure during decreasing NO bioavailability. Exp Physiol 2017; 102:164-179. [PMID: 27862525 DOI: 10.1113/ep085958] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/08/2016] [Indexed: 01/19/2023]
Abstract
NEW FINDINGS What is the central question of this study? We wanted to find out whether the relationship between rat arterial pulse waveform (APW) parameters and blood pressure could be described by known mathematical functions and find mathematical parameters for conditions of hypertension resulting from decreased NO bioavailability. What is the main finding and its importance? We found mathematical functions and their parameters that approximate the relationships of 12 APW parameters to systolic and diastolic blood pressure in conditions of decreased NO bioavailability. The results may assign APW parameters to decreased NO bioavailability, which may have predictive or diagnostic value. Information obtained from the arterial pulse waveform (APW) is useful for characterization of the cardiovascular system in particular (patho)physiological conditions. Our goal was to find out whether the relationships between rat APW parameters could be described by simple mathematical functions and to find mathematical parameters for conditions of hypertension resulting from decreased NO bioavailability. Therefore, we explored details of 14 left carotid APW parameters of anaesthetized male Wistar rats and mathematically characterized their relationship to systolic and diastolic blood pressure (BP) in conditions of a gradual reduction in NO bioavailability after administration of l-NAME. The right jugular vein of anaesthetized Wistar rats was cannulated for l-NAME administration. The left carotid artery was cannulated to detect the APW at high resolution. Here, we show the time-dependent parallel changes of 14 APW parameters before and after i.v. administration of l-NAME and present mathematical functions that approximate the relationships of 12 APW parameters to systolic and diastolic BP. Some APW parameters had minor (e.g. heart rate) or biphasic dependence on BP (e.g. relative level of the maximum rate of ventricular pressure decrease (dP/dtmin )), but all relationships, within a particular range of BP, could be approximated by known regression functions, as a linear function (e.g. pulse BP), exponential decay (e.g. relative level of the maximum rate of ventricular pressure increase (dP/dtmax )), exponential growth (systolic area), exponential rise to a maximum (relative augmentation index) or sigmoid function (e.g. increase of relative level of dP/dtmin ). The mathematical functions may assign APW parameters to decreased NO bioavailability. This may have predictive or diagnostic value.
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Affiliation(s)
- Anton Misak
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Frantisek Kristek
- Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Lenka Tomasova
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Marian Grman
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Elena Ondriasova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University, Bratislava, Slovak Republic
| | - Olga Krizanova
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - Karol Ondrias
- Institute of Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovak Republic
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Codreanu I, Robson MD, Rider OJ, Pegg TJ, Dasanu CA, Jung BA, Rotaru N, Clarke K, Holloway CJ. Details of left ventricular radial wall motion supporting the ventricular theory of the third heart sound obtained by cardiac MR. Br J Radiol 2014; 87:20130780. [PMID: 24641347 DOI: 10.1259/bjr.20130780] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Obtaining new details of radial motion of left ventricular (LV) segments using velocity-encoding cardiac MRI. METHODS Cardiac MR examinations were performed on 14 healthy volunteers aged between 19 and 26 years. Cine images for navigator-gated phase contrast velocity mapping were acquired using a black blood segmented κ-space spoiled gradient echo sequence with a temporal resolution of 13.8 ms. Peak systolic and diastolic radial velocities as well as radial velocity curves were obtained for 16 ventricular segments. RESULTS Significant differences among peak radial velocities of basal and mid-ventricular segments have been recorded. Particular patterns of segmental radial velocity curves were also noted. An additional wave of outward radial movement during the phase of rapid ventricular filling, corresponding to the expected timing of the third heart sound, appeared of particular interest. CONCLUSION The technique has allowed visualization of new details of LV radial wall motion. In particular, higher peak systolic radial velocities of anterior and inferior segments are suggestive of a relatively higher dynamics of anteroposterior vs lateral radial motion in systole. Specific patterns of radial motion of other LV segments may provide additional insights into LV mechanics. ADVANCES IN KNOWLEDGE The outward radial movement of LV segments impacted by the blood flow during rapid ventricular filling provides a potential substrate for the third heart sound. A biphasic radial expansion of the basal anteroseptal segment in early diastole is likely to be related to the simultaneous longitudinal LV displacement by the stretched great vessels following repolarization and their close apposition to this segment.
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Affiliation(s)
- I Codreanu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Codreanu I, Robson MD, Rider OJ, Pegg TJ, Dasanu CA, Jung BA, Clarke K, Holloway CJ. Effects of ventricular insertion sites on rotational motion of left ventricular segments studied by cardiac MR. Br J Radiol 2014; 86:20130326. [PMID: 24133098 DOI: 10.1259/bjr.20130326] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Obtaining new details for rotational motion of left ventricular (LV) segments using velocity encoding cardiac MR and correlating the regional motion patterns to LV insertion sites. METHODS Cardiac MR examinations were performed on 14 healthy volunteers aged between 19 and 26 years. Peak rotational velocities and circumferential velocity curves were obtained for 16 ventricular segments. RESULTS Reduced peak clockwise velocities of anteroseptal segments (i.e. Segments 2 and 8) and peak counterclockwise velocities of inferoseptal segments (i.e. Segments 3 and 9) were the most prominent findings. The observations can be attributed to the LV insertion sites into the right ventricle, limiting the clockwise rotation of anteroseptal LV segments and the counterclockwise rotation of inferoseptal segments as viewed from the apex. Relatively lower clockwise velocities of Segment 5 and counterclockwise velocities of Segment 6 were also noted, suggesting a cardiac fixation point between these two segments, which is in close proximity to the lateral LV wall. CONCLUSION Apart from showing different rotational patterns of LV base, mid ventricle and apex, the study showed significant differences in the rotational velocities of individual LV segments. Correlating regional wall motion with known orientation of myocardial aggregates has also provided new insights into the mechanisms of LV rotational motions during a cardiac cycle. ADVANCES IN KNOWLEDGE LV insertion into the right ventricle limits the clockwise rotation of anteroseptal LV segments and the counterclockwise rotation of inferoseptal segments adjacent to the ventricular insertion sites. The pattern should be differentiated from wall motion abnormalities in cardiac pathology.
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Affiliation(s)
- I Codreanu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Codreanu I, Pegg TJ, Selvanayagam JB, Robson MD, Rider OJ, Dasanu CA, Jung BA, Taggart DP, Golding SJ, Clarke K, Holloway CJ. Normal values of regional and global myocardial wall motion in young and elderly individuals using navigator gated tissue phase mapping. AGE (DORDRECHT, NETHERLANDS) 2014; 36:231-241. [PMID: 23604860 PMCID: PMC3889897 DOI: 10.1007/s11357-013-9535-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 04/05/2013] [Indexed: 06/02/2023]
Abstract
The purpose of this study was to evaluate normal values for regional and global myocardial wall motion parameters in young and elderly individuals, as detected by navigator gated high temporal resolution tissue phase mapping. Radial, longitudinal and circumferential ventricular wall motion, as well as ventricular torsion and longitudinal strain rates, were assessed in two age groups of volunteers, 23 ± 3 (n = 14) and 66 ± 7 years old (n = 9), respectively. All subjects were healthy, non-smokers without known cardiac disease. An increased global left ventricular (LV) torsion rate (peak systolic torsion rate 20.6 ± 2.0 versus 14.5 ± 1.0°/s/cm, peak diastolic torsion rate -25.2 ± 1.8 versus -14.1 ± 1.3°/s/cm) and a decrease in longitudinal LV motion (peak systolic values at mid-ventricle 5.9 ± 0.5 versus 8.5 ± 0.8 cm/s, peak diastolic values -10.7 ± 0.7 versus -15.2 ± 0.9 cm/s) in the older age group were the most prominent findings. Lower peak diastolic radial velocities with a longer time-to-peak values, most pronounced at the apex, are consistent with reduced diastolic function with ageing. Lower peak clockwise and counter-clockwise velocities at all LV levels revealed limitations in resting LV rotational motions in the older group. Significant changes in the undulating pattern of the rotational motions of the left ventricle were also observed. The results demonstrate distinct changes in regional and global myocardial wall motion in elderly individuals. Increased LV torsion rate and reduced LV longitudinal motion were particularly prominent in the older group. These parameters may have a role in the assessment of global LV contractility and help differentiate age-related changes from cardiac disease.
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Affiliation(s)
- Ion Codreanu
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford, OX1 3PT, UK,
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