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Vargas AI, Tarraf SA, Jennings T, Bellini C, Amini R. Vascular Remodeling During Late-Gestation Pregnancy: An In-Vitro Assessment of the Murine Ascending Thoracic Aorta. J Biomech Eng 2024; 146:071004. [PMID: 38345599 DOI: 10.1115/1.4064744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Indexed: 03/20/2024]
Abstract
Maternal mortality due to cardiovascular disease is a rising concern in the U.S. Pregnancy triggers changes in the circulatory system, potentially influencing the structure of the central vasculature. Evidence suggests a link between a woman's pregnancy history and future cardiovascular health, but our understanding remains limited. To fill this gap, we examined the passive mechanics of the murine ascending thoracic aorta during late gestation. By performing biaxial mechanical testing on the ascending aorta, we were able to characterize the mechanical properties of both control and late-gestation tissues. By examining mechanical, structural, and geometric properties, we confirmed that remodeling of the aortic wall occurred. Morphological and mechanical properties of the tissue indicated an outward expansion of the tissue, as reflected in changes in wall thickness (∼12% increase) and luminal diameter (∼6% increase) at its physiologically loaded state in the pregnant group. With these geometric adaptations and despite increased hemodynamic loads, pregnancy did not induce significant changes in the tensile wall stress at the similar physiological pressure levels of the pregnant and control tissues. The alterations also included reduced intrinsic stiffness in the circumferential direction (∼18%) and reduced structural stiffness (∼26%) in the pregnant group. The observed vascular remodeling maintained the elastic stored energy of the aortic wall under systolic loads, indicating preservation of vascular function. Data from our study of pregnancy-related vascular remodeling will provide valuable insights for future investigations of maternal cardiovascular health.
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Affiliation(s)
- Ana I Vargas
- Department of Bioengineering, Northeastern University, Boston, MA 02115
| | - Samar A Tarraf
- Department of Bioengineering, Northeastern University, Boston, MA 02115
- Northeastern University
| | - Turner Jennings
- Department of Mechanical and Industrial Engineering, Department of Bioengineering, Northeastern University, Boston, MA 02115
- Northeastern University
| | - Chiara Bellini
- Department of Bioengineering, Northeastern University, Boston, MA 02115
| | - Rouzbeh Amini
- Department of Mechanical and Industrial Engineering, Department of Bioengineering, Northeastern University, Boston, MA 02115
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Vargas AI, Tarraf SA, Fitzgibbons TP, Bellini C, Amini R. Biomechanical remodeling of the murine descending thoracic aorta during late-gestation pregnancy. Curr Res Physiol 2023; 6:100102. [PMID: 37575979 PMCID: PMC10415834 DOI: 10.1016/j.crphys.2023.100102] [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: 03/17/2023] [Revised: 06/29/2023] [Accepted: 07/04/2023] [Indexed: 08/15/2023] Open
Abstract
With the rise in maternal mortality rates and the growing body of epidemiological evidence linking pregnancy history to maternal cardiovascular health, it is essential to comprehend the vascular remodeling that occurs during gestation. The maternal body undergoes significant hemodynamic alterations which are believed to induce structural remodeling of the cardiovascular system. Yet, the effects of pregnancy on vascular structure and function have not been fully elucidated. Such a knowledge gap has limited our understanding of the etiology of pregnancy-induced cardiovascular disease. Towards bridging this gap, we measured the biaxial mechanical response of the murine descending thoracic aorta during a normotensive late-gestation pregnancy. Non-invasive hemodynamic measurements confirmed a 50% increase in cardiac output in the pregnant group, with no changes in peripheral blood pressure. Pregnancy was associated with significant wall thickening ( ∼14%), an increase in luminal diameter ( ∼6%), and material softening in both circumferential and axial directions. This expansive remodeling of the tissue resulted in a reduction in tensile wall stress and intrinsic tissue stiffness. Collectively, our data indicate that an increase in the geometry of the vessel may occur to accommodate for the increase in cardiac output and blood flow that occurs in pregnancy. Similarly, wall thickening accompanied by increased luminal diameter, without a change in blood pressure may be a necessary mechanism to decrease the tensile wall stress, and avoid pathophysiological events following late gestation.
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Affiliation(s)
- Ana I. Vargas
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, United States
| | - Samar A. Tarraf
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, United States
| | - Timothy P. Fitzgibbons
- Department of Medicine, Division of Cardiovascular Medicine, University of Massachusetts Medical School, Worcester, MA, 01655, United States
| | - Chiara Bellini
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, United States
| | - Rouzbeh Amini
- Department of Bioengineering, Northeastern University, Boston, MA, 02115, United States
- Department of Mechanical and Industrial Engineering, Northeastern University, Boston, MA, 02115, United States
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Kazma JM, van den Anker J, Allegaert K, Dallmann A, Ahmadzia HK. Anatomical and physiological alterations of pregnancy. J Pharmacokinet Pharmacodyn 2020; 47:271-285. [PMID: 32026239 PMCID: PMC7416543 DOI: 10.1007/s10928-020-09677-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 01/28/2020] [Indexed: 02/07/2023]
Abstract
The extensive metabolic demands of pregnancy require specific physiological and anatomical changes. These changes affect almost all organ systems, including the cardiovascular, respiratory, renal, gastrointestinal, and hematologic system. The placenta adds another layer of complexity. These changes make it challenging for clinicians to understand presenting signs and symptoms, or to interpret laboratory and radiological tests. Furthermore, these physiological alterations can affect the pharmacokinetics and pharmacodynamics of drugs. Drug safety in lactation is only supported by limited evidence. In addition, the teratogenic effects of medications are often extrapolated from animals, which further adds uncertainties. Unfortunately, pregnant women are only rarely included in clinical drug trials, while doses, regimens, and side effects are often extrapolated from studies conducted in non-pregnant populations. In this comprehensive review, we present the changes occurring in each system with its effects on the pharmacokinetic variables. Understanding these physiological changes throughout normal pregnancy helps clinicians to optimize the health of pregnant women and their fetuses. Furthermore, the information on pregnancy-related physiology is also critical to guide study design in this vulnerable 'orphan' population, and provides a framework to explore pregnancy-related pathophysiology such as pre-eclampsia.
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Affiliation(s)
- Jamil M Kazma
- Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - John van den Anker
- Division of Clinical Pharmacology, Children's National Hospital, Washington, DC, USA
- Pediatric Pharmacology and Pharmacometrics, University of Basel Children's Hospital, Basel, Switzerland
| | - Karel Allegaert
- Department of Development and Regeneration, and Department of Pharmaceutical and Pharmacological Sciences, Leuven, Belgium
- Department of Clinical Pharmacy, Erasmus MC, Rotterdam, The Netherlands
| | - André Dallmann
- Clinical Pharmacometrics, Research & Development, Pharmaceuticals, Bayer AG, Leverkusen, Germany
| | - Homa K Ahmadzia
- Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, The George Washington University School of Medicine and Health Sciences, Washington, DC, USA.
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Li K, Zhang S, Yang L, Jiang H, Chi Z, Wang A, Yang Y, Li X, Hao D, Zhang L, Zheng D. Changes of Arterial Pulse Waveform Characteristics with Gestational Age during Normal Pregnancy. Sci Rep 2018; 8:15571. [PMID: 30349022 PMCID: PMC6197191 DOI: 10.1038/s41598-018-33890-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 10/01/2018] [Indexed: 11/11/2022] Open
Abstract
Arterial pulse waveform analysis has been widely used to reflect physiological changes in the cardiovascular system. This study aimed to comprehensively investigate the changes of waveform characteristics of both photoplethysmographic (PPG) and radial pulses with gestational age during normal pregnancy. PPG and radial pulses were simultaneously recorded from 130 healthy pregnant women at seven gestational time points. After normalizing the arterial pulse waveforms, the abscissa of notch point, the total pulse area and the reflection index were extracted and compared between different measurement points and between the PPG and radial pulses using post-hoc multiple comparisons with Bonferrioni correction. The results showed that the effect of gestational age on all the three waveform characteristics was significant (all p < 0.001) after adjusting for maternal age, heart rate and blood pressures. All the three waveform characteristics demonstrated similar changing trends with gestational age, and they were all significantly different between the measurements from gestational week 12–15 and the others (all p < 0.05, except for the PPG total pulse area between the first and second measurement points). In conclusion, this study has comprehensively quantified similar changes of both PPG and radial pulse waveform characteristics with gestational age.
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Affiliation(s)
- Kunyan Li
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China.,Department of Medical Science and Public Health, Faculty of Medical Science, Anglia Ruskin University, Chelmsford, CM1 1SQ, UK
| | - Song Zhang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Lin Yang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China.
| | - Hongqing Jiang
- Haidian Maternal & Child Health Hospital, Beijing, 100026, China
| | - Zhenyu Chi
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Anran Wang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Yimin Yang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Xuwen Li
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Dongmei Hao
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Lei Zhang
- College of Life Science and Bioengineering, Beijing University of Technology, Beijing, 100124, China
| | - Dingchang Zheng
- Department of Medical Science and Public Health, Faculty of Medical Science, Anglia Ruskin University, Chelmsford, CM1 1SQ, UK.
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Abstract
Cerebral blood flow (CBF) regulation is an indicator of cerebrovascular health increasingly recognized as being influenced by physical activity. Although regular exercise is recommended during healthy pregnancy, the effects of exercise on CBF regulation during this critical period of important blood flow increase and redistribution remain incompletely understood. Moreover, only a few studies have evaluated the effects of human pregnancy on CBF regulation. The present work summarizes current knowledge on CBF regulation in humans at rest and during aerobic exercise in relation to healthy pregnancy. Important gaps in the literature are highlighted, emphasizing the need to conduct well-designed studies assessing cerebrovascular function before, during and after this crucial life period to evaluate the potential cerebrovascular risks and benefits of exercise during pregnancy.
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Zhong Q, Xu J, Long Y, Deng Y, Hu J, Li X, Qiu X. Interaction of body mass index and hemoglobin concentration on blood pressure among pregnant women in Guangxi, China. BMC Public Health 2014; 14:474. [PMID: 24885822 PMCID: PMC4030466 DOI: 10.1186/1471-2458-14-474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 05/06/2014] [Indexed: 11/23/2022] Open
Abstract
Background Body mass index (BMI) and hemoglobin (Hb) are positively associated with hypertensive disorders among pregnant women. The aim of this study was to estimate a potential interaction between high BMI and high Hb concentrations on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in pregnancy. Methods We recruited 4497 single-birth women aged 18–43 years who received routine antenatal care at three hospitals of Guigang, Guangxi, China, from December 2007 to January 2011. Of 4497 participants, 3472 women were in the first trimester, with following up, 2986 women and 2261 women were left in the second and third trimester, respectively. Clinical data were derived from medical records of each woman. We used multivariable linear regression, by trimesters of pregnancy, to evaluate the associations of high BMI and high Hb concentrations with SBP and DBP according to cross-sectional design. Results In multivariable analyses, BMI was positively associated with SBP throughout all trimesters, but the corresponding association for Hb concentrations only in the first trimester, whereas both BMI and Hb concentrations were positively associated with DBP in the first and third trimesters. After full adjustment for confounding, the average differences in SBP and DBP comparing women with high BMI and high Hb to those with non-high BMI and non-high Hb were 2.9 mmHg (95% CI: 0.8 to 5.0 mmHg) and 3.9 mmHg (95% CI: 1.5 to 6.3 mmHg) in the first trimester, 2.6 mmHg (95% CI: 0.4 to 4.8 mmHg) and 1.5 mmHg (95% CI: -1.3 to 4.3 mmHg) in the second trimester, and 4.8 mmHg (95% CI: 2.3 to 7.4 mmHg) and 5.7 mmHg (95% CI: 3.2 to 8.3 mmHg) in the third trimester, respectively. With respect to the interaction, significant combined effects between high BMI and high Hb were confirmed on SBP (P = 0.02) and DBP (P = 0.004) in the third trimester, and the amount of interaction on SBP and DBP were 2.0 mmHg (95% CI: 0.1 to 3.9 mmHg) and 2.3 mmHg (95% CI: 0.4 to 4.3 mmHg), respectively. Conclusion Our findings suggest that high BMI and high Hb concentrations may have a synergistic effect on blood pressure in late stage of pregnancy.
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Affiliation(s)
| | | | | | | | | | | | - Xiaoqiang Qiu
- Department of Epidemiology, Guangxi Medical University School of Public Health, 22 Shuangyong Road, Nanning, Guangxi 530021, China.
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Weissgerber TL, Davies GAL, Tschakovsky ME. Low flow-mediated constriction occurs in the radial but not the brachial artery in healthy pregnant and nonpregnant women. J Appl Physiol (1985) 2010; 108:1097-105. [PMID: 20185630 DOI: 10.1152/japplphysiol.00815.2009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Radial artery diameter decreases when a wrist cuff is inflated to stop blood flow to distal tissue. This phenomenon, referred to as low flow-mediated vasoconstriction (L-FMC), was proposed as a vascular function test. Recommendations that L-FMC be measured concurrently with flow-mediated dilation (FMD) were based on radial artery data. However, cardiovascular disease prediction studies traditionally measure brachial artery FMD. Therefore, studies should determine whether L-FMC occurs in the brachial artery. The hypothesis that reduced shear causes L-FMC has not been tested. Brachial and radial artery L-FMC and FMD were assessed in active nonpregnant (n=17), inactive nonpregnant (n=10), active pregnant (n=15, 34.1+/-1.2 wk gestation), and inactive pregnant (n=8, 34.2+/-2.2 wk gestation) women. Radial artery diameter decreased significantly during occlusion in all groups (nonpregnant, -4.4+/-4.2%; pregnant, -6.4+/-3.2%). Brachial artery diameter did not change in active and inactive nonpregnant, and inactive pregnant women; however, the small decrease in active pregnant women was significant. Occlusion decreased shear rate in both arteries, yet L-FMC only occurred in the radial artery. Radial artery L-FMC was not correlated with the reduction in shear rate. L-FMC occurs in the radial but not the brachial artery and is not related to changes in shear rate. Positive correlations between L-FMC (negative values) and FMD (positive values) suggest that radial artery FMD may be reduced among women who experience greater L-FMC. Studies should clarify the underlying stimulus and mechanisms regulating L-FMC, and test the hypothesis that endothelial dysfunction is manifested as enhanced brachial artery L-FMC, but attenuated radial artery L-FMC.
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Affiliation(s)
- Tracey L Weissgerber
- Department of Obstetrics, Gynecology, and Reproductive Science, Magee Women's Research Institute, 204 Craft Ave., Pittsburgh, PA 15213, USA.
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Robins JB, Woodward M, Lowe G, McCaul P, Cheyne H, Walker JJ. First trimester maternal blood rheology and pregnancy induced hypertension. J OBSTET GYNAECOL 2005; 25:746-50. [PMID: 16368576 DOI: 10.1080/01443610500314637] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
This study evaluates the relationship between the first trimester assessment of maternal rheology and the subsequent development of pregnancy induced hypertension. This is a prospective observational study based in the Glasgow Royal Maternity Hospital, Scotland. From an original population of 744 consecutive antenatal attendees a total of 579 women were booked at less than 14 weeks' gestation. The main study group is a further subset comprising 251 primigravid women booking with a singleton pregnancy without essential hypertension. Previously published data from a group of non-pregnant women of similar age drawn from the same local community was used for external comparison. Blood samples were collected at the booking visit, from which fibrinogen, red cell aggregation, haematocrit and plasma, whole blood, relative and corrected viscosities were recorded. Information was obtained from the case notes in retrospect starting approximately 1 year after the first patients had first been recruited into the trial. The overall outcome of the pregnancies was noted with particular reference to pregnancy induced hypertension (PIH), birth weight, antepartum haemorrhage, pre-term labour, perinatal death, condition at delivery and neonatal complication. Our results show PIH is associated with a significantly raised mean blood viscosity and fibrinogen at time of booking. All significance disappears after adjustment for smoking, diastolic blood pressure and age. Viscosity is, however, only marginally non-significant (p = 0.07). In conclusion, blood rheology, in particular blood viscosity and fibrinogen, may play a predictive role in the development of pregnancy-induced hypertension. When combined with measurement of smoking and diastolic blood pressure at booking, these measurements could be used to calculate a risk score for the development of PIH, allowing targeting of antenatal care. Further data is required.
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Affiliation(s)
- J B Robins
- Glasgow Royal Maternity Hospital, Scotland, UK.
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Kametas NA, Krampl E, McAuliffe F, Rampling MW, Nicolaides KH. Pregnancy at high altitude: a hyperviscosity state. Acta Obstet Gynecol Scand 2004; 83:627-33. [PMID: 15225186 DOI: 10.1111/j.0001-6349.2004.00434.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Pregnancy at high altitude has been associated with intrauterine growth restriction and preeclampsia. These conditions, at sea level, have been linked to increased hematocrit and blood viscosity. The aim of this study was to investigate the effect of high altitude on maternal hemorheology. METHODS This was a cross-sectional study. We examined 94 pregnant women at 10-38 weeks of gestation resident at high altitude (4370 m above sea level) and 75 at sea level, and 24 and 17 nonpregnant women at each altitude, respectively. Blood and plasma viscosity, hematocrit, plasma fibrinogen, albumin and total protein concentrations were determined in blood samples obtained after an overnight period of fasting. RESULTS Pregnancy at high altitude, compared to sea level, is characterized by higher hematocrit, blood viscosity (at high shear rate), plasma viscosity, total protein and fibrinogen concentrations (25%, 38%, 7%, 13.3% and 25%, respectively) and 6% lower albumin concentration. Nonpregnant women at high altitude, compared to sea level, had higher hematocrits, blood viscosity, plasma viscosity, total protein and fibrinogen concentrations (25%, 55%, 18%, 26% and 98%, respectively) and 13% lower albumin concentration. CONCLUSION Pregnancy at high altitude compared to sea level is characterized by increased blood viscosity as a result of increased hematocrit and plasma viscosity.
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Affiliation(s)
- Nikos A Kametas
- Harris Birthright Research Center for Fetal Medicine, King's College Hospital, London, UK.
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Edema pulmonar como complicación materna del uso de betamiméticos en gestación gemelar. CLINICA E INVESTIGACION EN GINECOLOGIA Y OBSTETRICIA 2001. [DOI: 10.1016/s0210-573x(01)77057-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Rabhi Y, Charras-Arthapignet C, Gris JC, Ayoub J, Brun JF, Lopez FM, Janbon C, Marès P, Dauzat M. Lower limb vein enlargement and spontaneous blood flow echogenicity are normal sonographic findings during pregnancy. JOURNAL OF CLINICAL ULTRASOUND : JCU 2000; 28:407-413. [PMID: 10993968 DOI: 10.1002/1097-0096(200010)28:8<407::aid-jcu5>3.0.co;2-s] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
PURPOSE We studied pregnancy-induced changes in lower limb venous function. METHODS We used plethysmography and sonography to assess the changes in venous wall distensibility, saphenous vein diameters, and spontaneous blood flow echogenicity in the common femoral veins in 190 consecutive women during and after uncomplicated pregnancies (total of 409 examinations). RESULTS The percentage of women with clinical symptoms and signs of venous insufficiency increased significantly during pregnancy. The mean diameters of the great and small saphenous veins also increased significantly, while occlusive venous plethysmography showed a decrease in parameters indicating vein distensibility. Spontaneous blood flow echogenicity in the common femoral veins was clearly visible or marked in 6% of cases during the first trimester of pregnancy, 63% during the second trimester, and 96% during the third trimester, versus 6% after delivery (p < 0.0001). The mean hematocrit decreased and the mean fibrinogen concentration increased during pregnancy. CONCLUSIONS The increase in lower limb venous pressure seen during pregnancy leads to venous overdistention and worsens blood stasis. Decreased venous flow velocity and rheological alterations result in increased red cell aggregation, giving rise to spontaneous blood flow echogenicity. Spontaneous blood flow echogenicity is therefore a normal finding during pregnancy and should not be mistaken for venous thrombosis.
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Affiliation(s)
- Y Rabhi
- Laboratory of Cardiovascular Physiology, Montpellier-Nîmes Faculty of Medicine, Avenue Kennedy, 30907 Nîmes, France
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Abstract
Dysbaric osteonecrosis is associated with exposure to large ambient pressure changes, and comprises necrotic lesions in the fatty marrow-containing shafts of the long bones, and the ball and socket joints (hips and shoulders). The fundamental causes are still in question and the illness remains a significant health hazard. Radiological and pathological features of both dysbaric and non-dysbaric osteonecrosis are indistinguishable and both are characterized by intramedullary venous stasis, ischemia and necrosis of bone. It has been generally accepted that gas bubbles (probably by initiating intramedullary venous stasis) are the prime cause of dysbaric osteonecrosis, as well as being responsible for Type 1 Decompression Sickness or 'the bends'. Importantly, however, not all series have found a correlation between dysbaric osteonecrosis and 'the bends'. Thus even though it is likely that gas bubbles remain the prime cause of dysbaric osteonecrosis, workers have proposed that in some cases there is another etiological factor which may exaggerate the pathologic effects of gas bubbles, making the bone more susceptible to necrosis. It is proposed that rapid compression by impeding venous drainage from bone initiates intramedullary venous stasis. In the presence of intramedullary gas bubbles, this may progress to thrombosis, ischemia and bone necrosis. The review offers an explanation for total sparing of the knee joint in dysbaric osteonecrosis, and sole involvement of the hip and shoulder (in terms of sub-articular lesions and subsequent joint collapse). In addition to continued observance of proper decompression procedures, a slower rate of compression may further reduce the incidence of dysbaric osteonecrosis. Bone death or osteonecrosis is a concept which Hippocrates put forward in antiquity (1), but it was not until 1794 that James Russell of Edinburgh wrote the first modern-day descriptions. In these cases infection was the predominant etiology (1,2). In 1888 Konig described necrosis of the adult femoral head without infection (3) (aseptic necrosis of bone) and in the same year Twynam reported a case of osteonecrosis in a caisson worker (4) in which there was still a significant infective component. In 1911 Bornstein and Plate, followed later and independently by Bassoe in 1913, presented radiological confirmation of aseptic necrosis of bone in compressed air workers (5). The first report of aseptic necrosis in an underwater diver subsequently appeared in 1936 (6). The condition of aseptic necrosis of bone in association with exposure to raised ambient pressure (previously referred to as caisson disease, pressure-induced osteoarthropathy (7), 'bone rot' (8) and other synonyms (6)) is now generally known as dysbaric osteonecrosis (6). Despite detailed examination of this problem by many authorities, dysbaric osteonecrosis still remains a significant occupational hazard with serious medico-legal consequences (5-13). This suggests that preventative measures are being based upon an incomplete understanding of the pathophysiology of the disease, and that other etiological factors are perhaps being overlooked.
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Affiliation(s)
- C D Hutter
- Department of Anaesthesia, City Hospital, Nottingham, UK
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13
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Martínez-Morales S, Bonillo-Perales A, Muñoz-Hoyos A, Puertas-Prieto A, Uberos-Fernández J, Molina-Carballo A, Bonillo-Perales JC, Sabatel-López R. The influence of maternal erythrocyte deformability on fetal growth, gestational age and birthweight. J Perinat Med 1999; 27:166-72. [PMID: 10503176 DOI: 10.1515/jpm.1999.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The increase in blood viscosity during pregnancy reduces maternal-fetal blood flow, which can lead to fetal hypoxia and acidosis. These factors have been related to a reduction in fetal growth and to premature births. We carried out a longitudinal study of 36 normal-term gestations at different stages of the pregnancy. We analyzed the erythocyte deformability, the intraerythocyte viscosity and the plasma viscosity in the mother, as well as the relation of these parameters to fetal growth (biparietral diameter (BPD) and length of the femur), birthweight, gestational age at birth and the Agpar score. The results obtained were as follows: from weeks 25 to 36 of pregnancy (30.9 (SD 2 weeks)) there occurs a significant increase in maternal erythocyte rigidity (p < 0.05) (despite the compensatory decrease in intracellular viscosity). This increase is very significantly related to the fetal biparietral diameter (r = -0.50, p < 0.01), the length of the fetal femur (r = -0.48, p < 0.02), gestational age at birth (r = -0.73, p < 0.0001, birthweight (r = -0.63, p < 0.001) and the Agpar score 5 minutes after birth (r = 0.67, p < 0.001). Our conclusions are that the reduction in erythocyte deformability (which we attribute to alterations in the fluidity or elasticity of its membrane) and the factors that increase the aggregation capacity of the red cells (modulators of blood viscosity and of blood flow in the placental intervillous space) are risk factors for reduced fetal growth, lower birthweight and lower gestational age at birth. By avoiding maternal hematocrit levels higher than 36% we could improve uteroplacental perfusion, fetal growth and perinatal results.
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Affiliation(s)
- S Martínez-Morales
- Department of Obstetrics and Gynecology, Hospital de Poniente, Almería, Spain
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Fisch B, Harel L, Amit S, Kaplan-Kraicer R, Mor N, Tadir Y, Ovadia J, Merlob P. Viscosity and refractive index of follicular fluid in relation to in vitro fertilization. J Assist Reprod Genet 1996; 13:468-71. [PMID: 8835674 DOI: 10.1007/bf02066526] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
PURPOSE To set the standard values of follicular fluid viscosity and refractive index, and to investigate a possible relationship between these physiological parameters and the outcome of in vitro fertilization treatment. DESIGN AND RESULTS 128 samples of follicular fluid were collected from 40 in vitro fertilization patients. Viscosity determinations (centipoise; mean +/- SD) for shear rates of 23, 46, 115, and 230 were 2.04 +/- 0.86, 1.84 +/- 0.49, 1.48 +/- 0.27, and 1.38 +/- 0.22, respectively. The average (+/- SD) refractive index was 1.030 +/- 0.002. There was no significant difference between the values of thawed frozen fluids and fresh samples of the same specimens. The data showed no correlation between follicular fluid viscosity or refractive index and the presence of oocytes, their maturation grade or their fertilizing capacity. CONCLUSIONS For the first time, values of the viscosity and refractive index of follicular fluid obtained during in vitro fertilization have been determined. However, these preliminary results did not reveal any relationship between the physiological parameters examined and the outcome of in vitro fertilization treatment.
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Affiliation(s)
- B Fisch
- Department of Obstetrics & Gynecology, Beilinson Medical Center, Petah-Tikva, Israel
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Lukacín S, Rychnavský J, Mojzis J, Mirossay L, Jurcová E, Nicák A. Changes of erythrocyte microrheology during normal pregnancy and after delivery. Eur J Obstet Gynecol Reprod Biol 1996; 66:125-8. [PMID: 8735732 DOI: 10.1016/0301-2115(96)02401-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVES The changes of blood hemorheology during pregnancy are still the subject of many studies. Erythrocyte membrane deformability (ED) as one of the main components forming blood hemorheology was studied in the present paper. STUDY DESIGN The changes in ED were measured in healthy non-pregnant women and in three groups of pregnant women in the first, second and third trimester. The last group consisted of women after delivery. The colloid-osmotic hemolysis method in relation to the change ionic strength was used for ED measurements. The significance of differences was evaluated by the unpaired Student's t-test. RESULTS The results revealed that ED during pregnancy progressively decreases but after delivery significantly increases. Statistical differences between means in all three trimesters were significant in comparison with non-pregnant women. CONCLUSION We conclude that the changes of ED are important for the normal course of gravidity and are probably connected to hormonal changes during pregnancy and after delivery.
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Affiliation(s)
- S Lukacín
- Department of Obstetrics and Gynecology, Medical Faculty, P.J. Safarik University, Kosice, Slovakia
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Muñoz A, Uberos J, Molina A, Valenzuela A, Cano D, Ruiz C, Molina Font JA. Relationship of blood rheology to lipoprotein profile during normal pregnancies and those with intrauterine growth retardation. J Clin Pathol 1995; 48:571-4. [PMID: 7665704 PMCID: PMC502692 DOI: 10.1136/jcp.48.6.571] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
AIMS The effects on fetal growth of hyperlipidaemia in pregnancy are not well understood at present. In this study the different lipid fractions in normal pregnancies and pregnancies complicated by intrauterine growth retardation (IUGR) were determined and related to changes in plasma and serum viscosity. METHODS Two groups of pregnant women were studied. Group 1 consisted of 35 healthy pregnant women aged between 21 and 38 years with no previous pathology and a normal pregnancy to term. Group 1 patients were studied at four periods defined at the start of the study: (1) < or = 17 weeks; (2) 18-24 weeks; (3) 25-32 weeks, (4) > or = 33 weeks. Group 2 consisted of 24 pregnant women aged between 16 and 34 years with ultrasound diagnosed IUGR confirmed after birth. Plasma lipids and plasma and serum viscosity were measured. RESULTS Plasma triglycerides, low density lipoprotein cholesterol, and total cholesterol increased progressively throughout pregnancy, with significantly higher values after week 25. Apolipoprotein A (ApoA) and triglyceride concentrations were significantly lower in the IUGR group than in the normal group. The HDL/ApoA ratio was greater in the IUGR group than in the control group, as was the ApoB/ApoA ratio. There were no differences in the other lipids. Plasma and serum viscosity was higher in the IUGR group than in the normal group. CONCLUSIONS Haemorheological modifications in the IUGR group are partly secondary to changes in high density lipoprotein metabolism and the competitive inhibition of fibrinolysis by ApoB, which is increased in pregnancies with IUGR. Changes in ApoA, and more specifically in the ApoB/ApoA ratio, could be good markers for the early detection of IUGR.
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Affiliation(s)
- A Muñoz
- Department of Paediatrics, University of Granada Hospital, Spain
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Oosterhof H, Wichers G, Fidler V, Aarnoudse JG. Blood viscosity and uterine artery flow velocity waveforms in pregnancy: a longitudinal study. Placenta 1993; 14:555-61. [PMID: 8290495 DOI: 10.1016/s0143-4004(05)80208-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In the course of pregnancy, whole blood viscosity (WBV) decreases, plasma viscosity (PV) increases and uteroplacental resistance to blood flow falls. According to the Hagen-Poiseuille law, viscosity influences resistance to blood flow. To investigate the contribution of these haemorheological changes to the decrease in resistance to blood flow in the uteroplacental circulation, a serial study was performed. Using blood viscosimetry and pulsed Doppler ultrasound recordings of the uterine arteries, 21 women with normal pregnancies were studied every 8 weeks from 12 weeks onwards. Statistical analysis revealed no significant relationship between WBV, PV and pulsatility index of the uterine arteries. It is concluded that the changes in blood viscosities are of minor influence on resistance to blood flow in the uteroplacental circulation throughout normal pregnancy. The vascular changes e.g. the considerable increase of the diameter of the spiral arteries have a much greater impact on resistance to blood flow.
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Affiliation(s)
- H Oosterhof
- Department of Obstetrics and Gynaecology, University Hospital Groningen, The Netherlands
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18
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Fisch B, Goldberg I, Ovadia J, Tadir Y. Physicochemical properties of follicular fluid and their relation to in vitro fertilization (IVF) outcome. JOURNAL OF IN VITRO FERTILIZATION AND EMBRYO TRANSFER : IVF 1990; 7:67-73. [PMID: 2193072 DOI: 10.1007/bf01135577] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Despite the limited data that are available concerning FF physicochemical properties, the following conclusions can be drawn. (1) FF temperature is lower than ovarian stroma and body temperatures. The physiological significance of this gradient is unknown. (2) Follicular size increases exponentially prior to ovulation. The relationship between FF volume and successful IVF outcome is well established. (3) A highly significant association exists between fertilization (but not embryo cleavage) and FF spectrophotometric absorbance at delta optic density of 455 nm. (4) FF behaves as a non-Newtonian fluid--its viscosity changes at different shear rates. Neither FF viscosity nor its refractive index was found to correlate with the presence of oocytes, their maturation grade, or their fertilizing capacity. (5) FF osmolarity is similar to that of the plasma. There is no information linking variations in FF osmolarity to IVF outcome. (6) FF pH is acidic, probably due to acid mucopolysaccharides. It appears that the intact follicle is capable of buffering any carbon dioxide which diffuses through its wall at the time of intraperitoneal insufflation. The transvaginal aspiration technique eliminates any possible effect of exogenous gas on FF pH. (7) Regarding the intact follicle, it was shown that (a) there is a small potential difference across the follicle wall, and (b) intrafollicular pressure remains steady prior to ovulation. This information may shed some light on mechanisms underlying FF formation and ovulation. No experiments relating these properties to IVF outcome have been performed.
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Affiliation(s)
- B Fisch
- Department of Obstetrics and Gynecology, Beilinson Medical Center, Sackler School of Medicine, Tel-Aviv University, Petah-Tikvah, Israel
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de Simone G, Devereux RB, Chien S, Alderman MH, Atlas SA, Laragh JH. Relation of blood viscosity to demographic and physiologic variables and to cardiovascular risk factors in apparently normal adults. Circulation 1990; 81:107-17. [PMID: 2297818 DOI: 10.1161/01.cir.81.1.107] [Citation(s) in RCA: 202] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Although increased blood viscosity occurs in several cardiovascular diseases, little is known of factors influencing blood rheology in normal adults. Accordingly, we examined the relations of whole blood viscosity (WBV) to its rheologic determinants (hematocrit level, plasma viscosity, protein concentration, and red cell aggregability and rigidity), to demographic and laboratory variables, and to cardiovascular risk factors in 128 normotensive employed adults. Hematocrit levels accounted for 67-84% of variability of WBV at shear rates from 208 to 0.1 sec-1 with lesser contributions from plasma viscosity, red cell aggregability, and rigidity (multiple r = 0.95-0.97); WBV was predicted accurately from standard measurements of hematocrit and total plasma protein levels (multiple r = 0.78-0.92 in "learning" and "test" analysis). Male sex, obesity, dietary Na+ intake, and increasing age had additive effects on WBV (multiple r greater than or equal to 0.59, p less than 0.00001); the last three of these factors and black race independently predicted plasma viscosity (multiple r = 0.36, p less than 0.001). Among regulators of plasma volume, plasma renin activity and urinary Na+ excretion bore independent positive relations to WBV. Diastolic and mean blood pressures were independent predictors of WBV and hematocrit levels (all p less than 0.05). Conventional risk factors (e.g., triglycerides, obesity, and cholesterol levels) were positively related to WBV or plasma viscosity. Thus, in apparently normal adults, 1) WBV or plasma viscosity are increased by male sex, obesity, high sodium intake, aging, and black race, 2) WBV is positively related to plasma renin activity, 3) WBV or plasma viscosity are related to diastolic and mean blood pressures, triglycerides and cholesterol concentrations, and 4) WBV can be predicted from simple measurements of hematocrit and total plasma protein levels.
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Affiliation(s)
- G de Simone
- Department of Medicine, New York Hospital-Cornell Medical Center, New York 10021
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