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Lantto J, Erkinaro T, Haapsamo M, Huhta H, Alanne L, Kokki M, Ohtonen P, Bhide A, Acharya G, Räsänen J. Peripheral chemoreflex activation and cardiac function during hypoxemia in near-term fetal sheep without placental compromise. J Appl Physiol (1985) 2021; 131:1486-1495. [PMID: 34590908 DOI: 10.1152/japplphysiol.01111.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A drop in arterial oxygen content activates fetal chemoreflex including an increase in sympathetic activity leading to peripheral vasoconstriction and redistribution of blood flow to protect the brain, myocardium, and adrenal glands. By using a chronically instrumented fetal sheep model with intact placental circulation at near-term gestation, we investigated the relationship between peripheral chemoreflex activation induced by hypoxemia and central hemodynamics. A total of 17 Åland landrace sheep fetuses at 115-128/145 gestational days were instrumented. Carotid artery was catheterized in 10 fetuses and descending aorta in 7 fetuses. After a 4-day recovery, baseline measurements of fetal arterial blood pressures, blood gas values, and fetal cardiovascular hemodynamics by pulsed Doppler ultrasonography were obtained under isoflurane anesthesia. Comparable data to baseline were collected 10 min (acute hypoxemia) and 60 min (prolonged hypoxemia) after maternal hypo-oxygenation to saturation level of 70%-80% was achieved. During prolonged hypoxemia, pH and base excess (BE) were lower and lactate levels were higher in the descending aorta than in the carotid artery. During hypoxemia mean arterial blood pressure (MAP) in the descending aorta increased, whereas in the carotid artery, MAP decreased. In addition, right pulmonary artery pulsatility index values increased, and the diastolic component in the aortic isthmus blood flow velocity waveform became more retrograde, thus decreasing the aortic isthmus antegrade/retrograde blood flow (AoI Net Flow) ratio. Both fetal ventricular cardiac outputs were maintained even during prolonged hypoxemia when significant fetal metabolic acidemia developed. Fetal chemoreflex activation induced by hypoxemia decreased the perfusion pressure in the cerebral circulation. Fetal weight-indexed left ventricular cardiac output (LVCO) or AoI Net Flow ratio did not correlate with a drop in carotid artery blood pressure.NEW & NOTEWORTHY During fetal hypoxemia with intact placental circulation, peripheral chemoreflex was activated, as demonstrated by an increase in the descending aorta blood pressure, pulmonary vasoconstriction, and an increase in retrograde diastolic AoI blood flow, while both ventricular cardiac outputs remained stable. However, perfusion pressure in the cerebral circulation decreased. These changes were seen even during prolonged hypoxemia when significant metabolic acidosis developed. Weight-indexed LVCO or AoI Net Flow ratio did not correlate with a drop in carotid artery blood pressure.
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Affiliation(s)
- Juulia Lantto
- Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
| | - Tiina Erkinaro
- Department of Anesthesiology, Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland
| | - Mervi Haapsamo
- Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
| | - Heikki Huhta
- Department of Surgery, Oulu University Hospital, University of Oulu, Oulu, Finland
| | - Leena Alanne
- Department of Obstetrics and Gynecology, Kuopio University Hospital, University of Eastern Finland, Kuopio, Finland.,Faculty of Health Sciences, School of Medicine, Institute of Clinical Medicine Kuopio, Kuopio, Finland
| | - Merja Kokki
- Department of Anesthesiology, Kuopio University Hospital, University of Eastern Finland, Kuopio, Finland
| | - Pasi Ohtonen
- Division of Operative Care, Medical Research Center Oulu, Oulu University Hospital, University of Oulu, Oulu, Finland
| | - Amarnath Bhide
- Department of Obstetrics and Gynecology, St. George's Hospital, London, United Kingdom.,Women's Health & Perinatal Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Ganesh Acharya
- Women's Health & Perinatal Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.,Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
| | - Juha Räsänen
- Department of Obstetrics and Gynecology, Fetal Medicine Center, Helsinki University Hospital, University of Helsinki, Helsinki, Finland
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Alanne L, Bhide A, Lantto J, Huhta H, Kokki M, Haapsamo M, Acharya G, Räsänen J. Nifedipine disturbs fetal cardiac function during hypoxemia in a chronic sheep model at near term gestation. Am J Obstet Gynecol 2021; 225:544.e1-544.e9. [PMID: 33887239 DOI: 10.1016/j.ajog.2021.04.228] [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: 12/15/2020] [Revised: 03/11/2021] [Accepted: 04/07/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Nifedipine is a widely used drug in pregnancies complicated by maternal hypertensive disorders that can be associated with placental insufficiency and fetal hypoxemia. The evidence regarding fetal myocardial responses to nifedipine in hypoxemia is limited. OBJECTIVE We hypothesized that nifedipine would not impair fetal sheep cardiac function under hypoxemic environment. In particular, we investigated the effects of nifedipine on fetal ventricular functional parameters and cardiac output. STUDY DESIGN A total of 21 chronically instrumented fetal sheep at 122 to 134 gestational days (term, 145 days) were included in this study. Fetal cardiac function was evaluated by measuring global longitudinal strain, indices describing ventricular systolic and diastolic function, and cardiac outputs using two-dimensional speckle tracking and tissue and spectral pulsed-wave Doppler echocardiography. Fetal carotid artery blood pressure and blood gas values were invasively monitored. After baseline data collection, fetal hypoxemia was induced by maternal hyperoxygenation. After hypoxemia phase data collection, 9 fetuses received nifedipine infusion, and 12 fetuses received saline infusion. Data were collected 30 and 120 minutes after the infusion was started. After 120 minutes of data collection, maternal and fetal oxygenation were normalized, and normoxemia phase data were collected, while infusion was continued. RESULTS Hypoxemia decreased fetal carotid artery mean arterial pressure from 40 (8) mm Hg to 35 (8) mm Hg (P<.007), and left ventricular global longitudinal strain showed less deformation than at baseline (P=.001). Under hypoxemia, nifedipine caused a reduction in right ventricular global longitudinal strain (P<.05), a decrease in right ventricular isovolumic relaxation velocity and its deceleration (P<.01) indicating diastolic dysfunction, and a drop in right ventricular cardiac output (P<.05). Nifedipine did not alter fetal left ventricular functional parameters or cardiac output. When normoxemia was restored, fetal right ventricular functional parameters and cardiac output returned to baseline level. CONCLUSION In hypoxemic fetus, nifedipine impaired right ventricular function and reduced its cardiac output. The detrimental effects of nifedipine on fetal right ventricular function were abolished, when normoxemia was restored. Our findings suggest that in a hypoxemic environment nifedipine triggers detrimental effects on fetal right ventricular function.
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Affiliation(s)
- Leena Alanne
- Department of Obstetrics and Gynecology, Kuopio University Hospital, Kuopio, Finland; Faculty of Health Sciences, Institute of Clinical Medicine, School of Medicine, University of Eastern Finland, Kuopio, Finland
| | - Amarnath Bhide
- Department of Obstetrics and Gynecology, St. George's Hospital, London, United Kingdom; Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway
| | - Juulia Lantto
- Department of Obstetrics and Gynecology, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Heikki Huhta
- Department of Surgery, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Merja Kokki
- Department of Anesthesiology and Intensive Care, Kuopio University Hospital, Kuopio, Finland
| | - Mervi Haapsamo
- Department of Surgery, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Ganesh Acharya
- Department of Obstetrics and Gynecology, Oulu University Hospital and University of Oulu, Oulu, Finland; Department of Obstetrics and Gynecology, University Hospital of North Norway, Tromsø, Norway; Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
| | - Juha Räsänen
- Fetal Medicine Center, Department of Obstetrics and Gynecology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
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Alanne L, Bhide A, Hoffren J, Lantto J, Huhta H, Kokki M, Haapsamo M, Acharya G, Räsänen J. Effects of nifedipine and sildenafil on placental hemodynamics and gas exchange during fetal hypoxemia in a chronic sheep model. Placenta 2019; 90:103-108. [PMID: 32056540 DOI: 10.1016/j.placenta.2019.12.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 12/11/2019] [Accepted: 12/15/2019] [Indexed: 11/25/2022]
Abstract
INTRODUCTION We hypothesized that nifedipine and sildenafil would have no detrimental effects on placental hemodynamics and gas exchange under fetal hypoxemia. METHODS In 33 chronically instrumented fetal sheep, placental volume blood flow (QPlac) and umbilical artery (UA) vascular impedance were measured by Doppler ultrasonography. Fetal carotid artery blood pressure and blood gas values were monitored. After baseline data collection, maternal and fetal hypoxemia were induced. Following hypoxemia phase data collection, 12 fetuses received sildenafil and 9 fetuses nifedipine infusion, and 12 fetuses served as controls receiving saline infusion. Data were collected 30 and 120 min after infusion was started. Then maternal oxygenation was normalized and normoxemia phase data were collected, while infusion was continued. RESULTS Hypoxemia significantly decreased fetal pO2 and blood pressure. In the sildenafil group at 30- and 120-min hypoxemia + infusion phases, fetal blood pressure and QPlac were significantly lower and pCO2 higher than at baseline without returning to baseline level at normoxemia + infusion phase. In hypoxemia, nifedipine did not affect fetal blood pressure or placental hemodynamics. Both in the sildenafil and nifedipine groups, fetal pO2 remained significantly lower at normoxemia + infusion phase than in the control group. Umbilical artery vascular impedance did not change during the experiment. DISCUSSION In fetal hypoxemia, sildenafil had detrimental effects on placental hemodynamics that disturbed placental gas exchange. Nifedipine did not alter placental hemodynamics in hypoxemia but disturbed placental gas exchange upon returning to normoxemia. Umbilical artery vascular impedance did not reflect alterations in placental hemodynamics.
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Affiliation(s)
- Leena Alanne
- Department of Obstetrics and Gynecology, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland
| | - Amarnath Bhide
- Department of Obstetrics and Gynecology, St. George's Hospital, London, United Kingdom; Women's Health & Perinatal Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Jonna Hoffren
- Department of Obstetrics and Gynecology, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland
| | - Juulia Lantto
- Department of Obstetrics and Gynecology, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Heikki Huhta
- Department of Surgery, Oulu University Hospital, Oulu, Finland
| | - Merja Kokki
- Department of Anesthesiology, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland
| | - Mervi Haapsamo
- Department of Obstetrics and Gynecology, Satakunta Central Hospital, Pori, Finland
| | - Ganesh Acharya
- Women's Health & Perinatal Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway; Department of Clinical Science, Intervention & Technology, Karolinska Institute and Center for Fetal Medicine Karolinska University Hospital, Stockholm, Sweden
| | - Juha Räsänen
- Department of Obstetrics and Gynecology, Oulu University Hospital and University of Oulu, Oulu, Finland; Department of Obstetrics and Gynecology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
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Lantto J, Erkinaro T, Haapsamo M, Huhta H, Voipio HM, Hohimer AR, Davis LE, Acharya G, Räsänen J. Foramen ovale blood flow and cardiac function after main pulmonary artery occlusion in fetal sheep. Exp Physiol 2019; 104:189-198. [PMID: 30578690 DOI: 10.1113/ep087423] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 12/18/2018] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? At near-term gestation, foramen ovale blood flow accounts for a significant proportion of fetal left ventricular output. Can the foramen ovale increase its volume blood flow when right ventricular afterload is increased by main pulmonary artery occlusion? What is the main finding and its importance? Foramen ovale volume blood flow increased during main pulmonary artery occlusion. However, this increase was attributable to an increase in fetal heart rate, because left ventricular stroke volume remained unchanged. These findings suggest that the foramen ovale has a limited capacity to increase its volume blood flow. ABSTRACT The foramen ovale (FO) accounts for the majority of fetal left ventricular (LV) output. Increased right ventricular afterload can cause a redistribution of combined cardiac output between the ventricles. To understand the capability of the FO to increase its volume blood flow and thus LV output, we mechanically occluded the main pulmonary artery in seven chronically instrumented near-term sheep fetuses. We hypothesized that FO volume blood flow and LV output would increase during main pulmonary artery occlusion. Fetal cardiac function and haemodynamics were assessed by pulsed and tissue Doppler at baseline, 15 and 60 min after occlusion of the main pulmonary artery and 15 min after occlusion was released. Fetal ascending aorta and central venous pressures and blood gas values were monitored. Main pulmonary artery occlusion initially increased fetal heart rate (P < 0.05) from [mean (SD)] 158 (7) to 188 (23) beats min-1 and LV cardiac output (P < 0.0001) from 629 (198) to 776 (283) ml min-1 . Combined cardiac output fell (P < 0.0001) from 1524 (341) to 720 (273) ml min-1 . During main pulmonary artery occlusion, FO volume blood flow increased (P < 0.001) from 507 (181) to 776 (283) ml min-1 . This increase was related to fetal tachycardia, because LV stroke volume did not change. Fetal ascending aortic blood pressure remained stable. Central venous pressure was higher (P < 0.05) during the occlusion than after it was released. During the occlusion, fetal pH decreased and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>P</mml:mi> <mml:mrow><mml:mi>C</mml:mi> <mml:msub><mml:mi>O</mml:mi> <mml:mn>2</mml:mn></mml:msub> </mml:mrow> </mml:msub> </mml:math> increased. Left ventricular systolic dysfunction developed while LV diastolic function was preserved. Right ventricular systolic and diastolic function deteriorated after the occlusion. In conclusion, the FO has a limited capacity to increase its volume blood flow at near-term gestation.
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Affiliation(s)
- Juulia Lantto
- Department of Obstetrics and Gynecology, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - Tiina Erkinaro
- Department of Anesthesiology, Oulu University Hospital, Oulu, Finland
| | - Mervi Haapsamo
- Department of Obstetrics and Gynecology, Satakunta Central Hospital, Pori, Finland
| | - Heikki Huhta
- Department of Surgery, Oulu University Hospital, Oulu, Finland
| | - Hanna-Marja Voipio
- Laboratory Animal Centre, Experimental Surgery, Oulu University Hospital and University of Oulu, Oulu, Finland
| | - A Roger Hohimer
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Lowell E Davis
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA
| | - Ganesh Acharya
- Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Science, University of Norway and University Hospital of Northern Norway, Tromsø, Norway.,Department of Clinical Science, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
| | - Juha Räsänen
- Department of Obstetrics and Gynecology, Oulu University Hospital and University of Oulu, Oulu, Finland.,Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, OR, USA.,Department of Obstetrics and Gynecology, Helsinki University Hospital and University of Helsinki, Helsinki, Finland
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5
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Bhide A, Alanne L, Rasanen J, Huhta H, Junno J, Kokki M, Erkinaro T, Ohtonen P, Haapsamo M, Acharya G. Effect of Sildenafil on Pulmonary Circulation and Cardiovascular Function in Near-Term Fetal Sheep During Hypoxemia. Reprod Sci 2018; 26:337-347. [PMID: 29716434 DOI: 10.1177/1933719118773412] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sildenafil is a potential new treatment for placental insufficiency in human pregnancies as it reduces the breakdown of vasodilator nitric oxide. Pulmonary vasodilatation is observed in normoxemic fetuses following sildenafil administration. Placental insufficiency often leads to fetal hypoxemia that can cause pulmonary vasoconstriction and fetal cardiac dysfunction as evidenced by reduced isovolumic myocardial velocities. We tested the hypotheses that sildenafil, when given directly to the hypoxemic fetus, reverses reactive pulmonary vasoconstriction, increases left ventricular cardiac output by increasing pulmonary venous return, and ameliorates hypoxemic myocardial dysfunction. We used an instrumented sheep model. Fetuses were made hypoxemic over a mean (standard deviation) duration of 41.3 (9.5) minutes and then given intravenous sildenafil or saline infusion. Volume blood flow through ductus arteriosus was measured with an ultrasonic transit-time flow probe. Fetal left and right ventricular outputs and lung volume blood flow were calculated, and ventricular function was examined using echocardiography. Lung volume blood flow decreased and the ductus arteriosus volume blood flow increased with hypoxemia. There was a significant reduction in left ventricular and combined cardiac outputs during hypoxemia in both groups. Hypoxemia led to a reduction in myocardial isovolumic velocities, increased ductus venosus pulsatility, and reduced left ventricular myocardial deformation. Direct administration of sildenafil to hypoxemic fetus did not reverse the redistribution of cardiac output. Furthermore, fetal cardiac systolic and diastolic dysfunction was observed during hypoxemia, which was not improved by fetal sildenafil treatment. In conclusion, sildenafil did not improve pulmonary blood flow or cardiac function in hypoxemic sheep fetuses.
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Affiliation(s)
- Amarnath Bhide
- 1 Women's Health & Perinatal Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway
| | - Leena Alanne
- 2 Department of Obstetrics and Gynecology, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland
| | - Juha Rasanen
- 3 Department of Obstetrics and Gynecology, Helsinki University Hospital, Helsinki, Finland.,4 Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
| | - Heikki Huhta
- 4 Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
| | - Juulia Junno
- 4 Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland
| | - Merja Kokki
- 5 Department of Anesthesiology, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland
| | - Tiina Erkinaro
- 6 Department of Anesthesiology, Oulu University Hospital, Oulu, Finland
| | - Pasi Ohtonen
- 7 Department of Statistics, Oulu University Hospital, Oulu, Finland
| | - Mervi Haapsamo
- 8 Department of Obstetrics and Gynecology, Lapland Central Hospital, Finland
| | - Ganesh Acharya
- 1 Women's Health & Perinatal Research Group, Department of Clinical Medicine, UiT-The Arctic University of Norway, Tromsø, Norway.,9 Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institute, Stockholm, Sweden
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6
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Huhta H, Junno J, Haapsamo M, Erkinaro T, Ohtonen P, Davis LE, Hohimer AR, Acharya G, Rasanen J. Fetal sheep central haemodynamics and cardiac function during occlusion of the ascending aorta. Exp Physiol 2017; 103:58-67. [DOI: 10.1113/ep086500] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 10/31/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Heikki Huhta
- Department of Obstetrics and Gynecology; University of Oulu; Oulu Finland
| | - Juulia Junno
- Department of Obstetrics and Gynecology; University of Oulu; Oulu Finland
| | - Mervi Haapsamo
- Department of Obstetrics and Gynecology; University of Oulu; Oulu Finland
| | - Tiina Erkinaro
- Department of Anesthesiology and Surgery; Oulu University Hospital; Oulu Finland
| | - Pasi Ohtonen
- Division of Operative Care and Medical Research Center Oulu; Oulu University Hospital and University of Oulu; Finland
| | - Lowell E. Davis
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology; Oregon Health & Science University; Portland OR USA
| | - A. Roger Hohimer
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology; Oregon Health & Science University; Portland OR USA
| | - Ganesh Acharya
- Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Science; University of Norway and University Hospital of Northern Norway; Tromsø Norway
- Department of Clinical Science, Intervention and Technology; Karolinska Institute; Stockholm Sweden
| | - Juha Rasanen
- Department of Obstetrics and Gynecology; University of Oulu; Oulu Finland
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology; Oregon Health & Science University; Portland OR USA
- Department of Obstetrics and Gynecology; Helsinki University Hospital; Helsinki Finland
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7
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Bhide A, Vuolteenaho O, Haapsamo M, Erkinaro T, Rasanen J, Acharya G. Effect of Hypoxemia with or without Increased Placental Vascular Resistance on Fetal Left and Right Ventricular Myocardial Performance Index in Chronically Instrumented Sheep. ULTRASOUND IN MEDICINE & BIOLOGY 2016; 42:2589-2598. [PMID: 27544438 DOI: 10.1016/j.ultrasmedbio.2016.07.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 06/09/2016] [Accepted: 07/06/2016] [Indexed: 06/06/2023]
Abstract
Myocardial performance index (MPI) is increased in growth-restricted fetuses with placental insufficiency, but it is unknown if this is due to fetal hypoxemia or increased placental vascular resistance (Rplac). We used chronically instrumented sheep fetuses (n = 24). In 12 fetuses, placental embolization was performed 24 h before experiments. On the day of the experiment, left (LV) and right (RV) ventricular MPIs were obtained by pulsed Doppler at baseline and in the hypoxemia and recovery phases. At baseline, Rplac was greater and fetal pO2 lower in the placental embolization group, but RV and LV MPIs were comparable to those of the control group. During hypoxemia, mean LV MPI increased significantly only in fetuses with an intact placenta (0.34 vs. 0.46), returning to baseline during the recovery phase. Right ventricular MPI was unaffected. We conclude that fetal LV function is sensitive to acute hypoxemia. Exposure to chronic hypoxemia could pre-condition the fetal heart and protect its function with worsening hypoxemia.
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Affiliation(s)
- Amar Bhide
- Women's Health & Perinatal Research Group, UiT-The Arctic University of Norway, Tromsø, Norway; Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway.
| | - Olli Vuolteenaho
- Biomedicine Unit, Department of Physiology, University Hospital of Oulu, Oulu, Finland
| | - Mervi Haapsamo
- Department of Obstetrics and Gynecology, University Hospital of Oulu, Oulu, Finland
| | - Tiina Erkinaro
- Department of Anesthesiology, University Hospital of Oulu, Oulu, Finland
| | - Juha Rasanen
- Department of Obstetrics and Gynecology, University of Eastern Finland, Kuopio, Finland; Oregon Health and Sciences University, Portland, Oregon, USA
| | - Ganesh Acharya
- Women's Health & Perinatal Research Group, UiT-The Arctic University of Norway, Tromsø, Norway; Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway; Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institute, Stockholm, Sweden
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8
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Hashima JN, Rogers V, Langley SM, Ashraf M, Sahn DJ, Ohtonen P, Davis LE, Hohimer AR, Rasanen J. Fetal ventricular interactions and wall mechanics during ductus arteriosus occlusion in a sheep model. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:1020-1028. [PMID: 25701524 PMCID: PMC4407698 DOI: 10.1016/j.ultrasmedbio.2014.11.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 11/04/2014] [Accepted: 11/06/2014] [Indexed: 06/04/2023]
Abstract
We investigated the effect of fetal sheep ductus arteriosus occlusion (DO) on the distribution of cardiac output and left and right ventricular function by tissue and pulsed Doppler at baseline; after 15 and 60 min of DO induced with a vascular occluder; and 15 min after release of DO. Ductal occlusion decreased fetal pO2. Mean left ventricular output increased (p < 0.001) from 725 to 1013 mL/min, and right ventricular (1185 mL/min vs. 552 mL/min) and systemic (1757 mL/min vs. 1013 mL/min) cardiac outputs fell (p < 0.001) after 15 min of DO, compared with baseline. Pulmonary vascular impedance decreased and volume blood flow increased more than threefold during DO, whereas foramen ovale volume blood flow remained unchanged. Left ventricular systolic function was unaffected, whereas isovolumic relaxation velocity deceleration decreased. Right ventricular functional indices remained unchanged. We conclude that DO increased pulmonary volume blood flow, not foramen ovale volume blood flow. Left ventricular output increased, although not as much as right ventricular output fell, resulting in decreased systemic cardiac output. During DO, left ventricular function exhibited diminished relaxation.
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Affiliation(s)
- Jason N Hashima
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, USA
| | - Vanessa Rogers
- Division of Cardiothoracic Surgery, Department of Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Stephen M Langley
- Division of Cardiothoracic Surgery, Department of Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Muhammed Ashraf
- Division of Pediatric Cardiology, Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, USA
| | - David J Sahn
- Division of Pediatric Cardiology, Department of Pediatrics, Oregon Health & Science University, Portland, Oregon, USA
| | - Pasi Ohtonen
- Department of Anesthesiology and Surgery, Oulu University Hospital, Oulu, Finland
| | - Lowell E Davis
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, USA
| | - A Roger Hohimer
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, USA
| | - Juha Rasanen
- Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon, USA; Department of Obstetrics and Gynecology, Oulu University Hospital, Oulu, Finland; Department of Obstetrics and Gynecology, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.
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Fetal cardiac function after labetalol or pindolol for maternal hypertension in a sheep model of increased placental vascular resistance. Eur J Obstet Gynecol Reprod Biol 2013; 166:18-22. [DOI: 10.1016/j.ejogrb.2012.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 08/06/2012] [Accepted: 09/03/2012] [Indexed: 11/17/2022]
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Junno J, Bruun E, Gutierrez JH, Erkinaro T, Haapsamo M, Acharya G, Räsänen J. Fetal sheep left ventricle is more sensitive than right ventricle to progressively worsening hypoxemia and acidemia. Eur J Obstet Gynecol Reprod Biol 2012; 167:137-41. [PMID: 23266204 DOI: 10.1016/j.ejogrb.2012.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Accepted: 11/24/2012] [Indexed: 01/15/2023]
Abstract
OBJECTIVE In a sheep model we tested the hypothesis that the fetal left ventricle is less tolerant to worsening acidemia than the right ventricle. STUDY DESIGN At 106-124/145 days of gestation, 12 fetuses were instrumented. After a 4-day recovery, placental vascular resistance was increased by fetal angiotensin (AT) II infusion. After a 2h ATII infusion, to further deteriorate fetal oxygenation, maternal hypoxemia was induced. Fetal cardiac function and hemodynamics were assessed by tissue Doppler imaging (TDI) and pulsed Doppler imaging. Ultrasonography was performed at baseline, at 1 and 2h after the beginning of ATII infusion and during the ATII+hypoxemia phase. RESULTS Fetal pH and pO₂ decreased significantly and progressively during the experiment. Left ventricular TDI-derived isovolumic relaxation velocity (IVRV) was lower during ATII 2h and ATII+hypoxemia phases than at baseline. The IVRV deceleration was significantly less during the ATII+hypoxemia phase than at baseline. Right ventricular IVRV was significantly lower during the ATII+hypoxemia phase than at baseline. IVRV deceleration did not change. Only left ventricular IVRV deceleration correlated with fetal pO₂ (R=0.36, p<0.05). Fetal right and left ventricular cardiac outputs, as well as umbilical artery, aortic isthmus and ductus venosus pulsatility indices remained unchanged during the experiment. CONCLUSION Our results show that signs of cardiac dysfunction develop earlier in the left ventricle than in the right ventricle. The fetal left ventricle seems to be more sensitive to progressively worsening hypoxemia and acidemia than the right ventricle.
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Affiliation(s)
- Juulia Junno
- Department of Obstetrics and Gynecology, University of Oulu, Oulu, Finland
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11
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Bernard LS, Hashima JN, Hohimer AR, Sahn DJ, Ashraf M, Vuolteenaho O, Davis LE, Rasanen J. Myocardial performance and its acute response to angiotensin II infusion in fetal sheep adapted to chronic anemia. Reprod Sci 2011; 19:173-80. [PMID: 22051849 DOI: 10.1177/1933719111415545] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Fetal chronic anemia causes lengthening of cardiomyocytes. In adults, severe left ventricular overload may lead to irreversible ventricular dysfunction. We hypothesized that in sheep fetuses with chronic anemia, remodeled myocardium would less successfully respond to angiotensin II (AT II) infusion than in fetuses without anemia. A total of 14 ewes with twin pregnancy underwent surgery at 113 ± 1 days of gestation. After a recovery period, anemia was induced by isovolumic hemorrhage in 1 fetus of each pair. At 126 ± 1 days of gestation, longitudinal myocardial velocities of the right (RV) and left (LV) ventricles were assessed at the level of the atrioventricular valve annuli via tissue Doppler imaging. Cardiac outputs were calculated by pulsed Doppler ultrasound. All measurements were performed at baseline and during fetal AT II infusion. Fetal serum cardiac natriuretic peptide (N-terminal peptide of proatrial natriuretic peptide [NT-proANP] and B-type natriuretic peptide [BNP]) concentrations were determined. Nine ewes successfully completed the experiment. At baseline, ventricular free wall thicknesses, cardiac outputs, and NT-proANP levels were significantly greater in the anemic fetuses than in the controls. The LV isovolumic contraction velocity (IVCV) acceleration and isovolumic relaxation velocity (IVRV) deceleration were lower (P < .05) in the anemic fetuses than in the controls. In the anemic fetuses, there was a positive correlation (R = .93, P < .01) between RV IVRV deceleration and NT-proANP concentration. Angiotensin II infusion increased (P < .05) LV IVCV acceleration in the anemic fetuses. We conclude that in anemic sheep fetuses, myocardial adaptation is associated with impaired LV early contraction and relaxation. However, the LV can improve its contractility with an inotropic stimulus, even in the presence of increased afterload.
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Affiliation(s)
- Leah S Bernard
- Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland, OR 97239, USA
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12
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Effect of angiotensin II on the left ventricular function in a near-term fetal sheep with metabolic acidemia. J Pregnancy 2011; 2011:634240. [PMID: 22132338 PMCID: PMC3206332 DOI: 10.1155/2011/634240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 08/17/2011] [Accepted: 08/17/2011] [Indexed: 11/18/2022] Open
Abstract
We tested the hypothesis that, in acute metabolic acidemia, the fetal left ventricle (LV) has the capacity to increase its contractility in response to angiotensin II infusion. Eleven ewes and their fetuses were instrumented at 127–138/145 days of gestation. The effect of angiotensin II on fetal LV function was assessed using intraventricular pressure catheter and tissue Doppler imaging (TDI). Angiotensin II increased fetal arterial blood pressure, whereas pH and pO2 decreased. The heart rate and systemic venous pressure were not affected significantly. The LV end-diastolic and end-systolic pressures, as well as dP/dtmax, increased. The TDI-derived LV longitudinal myocardial isovolumic contraction velocity and its acceleration and velocity during early filling were higher than those at baseline. The incidence of absent isovolumic relaxation velocity was greater during angiotensin II infusion. In summary, during acute metabolic acidemia, the fetal left ventricle could increase its contractility in response to inotropic stimulus even in the presence of increased afterload. The diastolic LV function parameters were altered by angiotensin II.
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13
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Xiong L, Bernard LS, Hashima JN, Deng YB, Zhou Z, Ashraf M, Hohimer AR, Davis LE, Shentu W, Sahn DJ, Rasanen J. Regional myocardial function and response to acute afterload increase in chronically anemic fetal sheep: evaluation by two-dimensional strain echocardiography. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:2042-2047. [PMID: 20950931 DOI: 10.1016/j.ultrasmedbio.2010.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Revised: 08/20/2010] [Accepted: 08/23/2010] [Indexed: 05/30/2023]
Abstract
We hypothesized that in chronic fetal anemia, remodeling of the myocardium is related to abnormalities in regional wall motion and acutely increased afterload further disturbs myocardial strain. Chronic anemia was induced in one fetus of each of seven sheep twin pregnancies. The fetuses were studied by two-dimensional (2-D) strain echocardiography at baseline and during increased afterload via angiotensin II (AT II) infusion. At baseline, the peak systolic longitudinal, radial and circumferential strains in the left ventricular lateral wall in anemic fetuses were lower than those in the controls (all p<0.05). During AT II, the circumferential strain of right ventricular free wall decreased significantly both in the control and anemic fetuses. Left ventricular free wall systolic strains were not affected by AT II. Fetal myocardial remodeling in chronic anemia decreases left ventricular systolic free wall strains. The myocardial adaptation does not change ventricular responses to acutely increased afterload.
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Affiliation(s)
- Li Xiong
- Wuhan General Hospital of Guangzhou Command, Wuhan, China
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14
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Mäkikallio K, Acharya G, Erkinaro T, Kavasmaa T, Haapsamo M, Huhta JC, Räsänen J. Ductus venosus velocimetry in acute fetal acidemia and impending fetal death in a sheep model of increased placental vascular resistance. Am J Physiol Heart Circ Physiol 2010; 298:H1229-34. [DOI: 10.1152/ajpheart.01299.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether hypoxemia without acidemia affects ductus venosus (DV) blood velocity waveform pattern in sheep fetuses with intact placenta and whether worsening acidemia and impending fetal death are related to changes in DV velocimetry in fetuses with increased placental vascular resistance. A total of 34 fetuses were instrumented at 115–136/145 days of gestation. Placental embolization was performed in 22 fetuses on the fourth postoperative day, 24 h before the experiment. The control group was comprised of 12 fetuses with intact placenta. The experimental protocol consisted of fetal hypoxemia that was induced by replacing maternal inhaled oxygen with medical air. To further deteriorate fetal oxygenation and blood-gas status, uterine artery volume blood flow was reduced by maternal hypotension. Fetuses that underwent placental embolization were divided into two groups according to fetal outcome. Group 1 consisted of 12 fetuses that completed the experiment, and group 2 comprised 10 fetuses that died during the experiment. DV pulsatility index for veins (PIV) and fetal cardiac outputs (COs) were calculated. Placental volume blood flow, fetal blood pressures, and acid base and lactate values were monitored invasively. On the experimental day, the mean gestational age did not differ significantly between the groups. In groups 1 and 2, the baseline mean DV PIV and fetal COs were not statistically significantly different from the control group. In the control group, the DV PIV values increased significantly with hypoxemia. In groups 1 and 2, the DV PIV values did not change significantly, even with worsening acidemia and imminent fetal death in group 2. During the experiment, the fetal COs remained unchanged. We conclude that fetal hypoxemia increases the pulsatility of DV blood velocity waveform pattern. In fetuses with elevated placental vascular resistance, DV pulsatility does not increase further in the presence of severe and worsening fetal acidemia and impending fetal death.
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Affiliation(s)
| | - Ganesh Acharya
- Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, and Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway
| | | | | | | | - James C Huhta
- Women's Health and Perinatology Research Group, Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø, and Department of Obstetrics and Gynecology, University Hospital of Northern Norway, Tromsø, Norway
- Congenital Heart Institute of Florida, Tampa Bay, Florida; and
| | - Juha Räsänen
- Departments of 1Obstetrics and Gynecology,
- Physiology, University of Oulu, Oulu, Finland
- Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland, Oregon
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15
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Erkinaro T, Kavasmaa T, Ylikauma L, Mäkikallio K, Haapsamo M, Acharya G, Ohtonen P, Alahuhta S, Räsänen J. Placental and Fetal Hemodynamics After Labetalol or Pindolol in a Sheep Model of Increased Placental Vascular Resistance and Maternal Hypertension. Reprod Sci 2009; 16:749-57. [DOI: 10.1177/1933719109335068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Tiina Erkinaro
- Department of Anesthesiology, Oulu University Hospital, Finland,
| | - Tomi Kavasmaa
- Department of Anesthesiology, Oulu University Hospital, Finland
| | - Laura Ylikauma
- Department of Anesthesiology, Oulu University Hospital, Finland
| | - Kaarin Mäkikallio
- Department of Obstetrics and Gynecology, Oulu University Hospital, Finland
| | - Mervi Haapsamo
- Department of Obstetrics and Gynecology, Oulu University Hospital, Finland
| | - Ganesh Acharya
- Department of Obstetrics and Gynecology, Institute of Clinical Medicine, University of Tromsø and University Hospital of Northern Norway, Tromsø, Norway
| | - Pasi Ohtonen
- Department of Surgery, Oulu University Hospital, Finland
| | - Seppo Alahuhta
- Department of Anesthesiology, Oulu University Hospital, Finland
| | - Juha Räsänen
- Department of Obstetrics and Gynecology, Oulu University Hospital, Finland
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16
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Kavasmaa T, Mäkikallio K, Erkinaro T, Acharya G, Haapsamo M, Alahuhta S, Räsänen J. Significance of retrograde diastolic uterine artery blood flow during regional anesthesia in instrumented pregnant sheep. Acta Anaesthesiol Scand 2008; 52:1291-7. [PMID: 18823471 DOI: 10.1111/j.1399-6576.2008.01764.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND We studied the interactions between uterine and placental hemodynamics during maternal hypotension in chronically instrumented fetal sheep. In addition, we investigated maternal hemodynamic characteristics, fetoplacental hemodynamics and fetal acid-base status when a retrograde diastolic uterine artery blood flow pattern is present during maternal hypotension. METHODS Invasive maternal and fetal hemodynamic parameters, uterine (Q(UtA)) and placental (Q(UA)) volume blood flows and acid-base values were examined in 24 chronically instrumented sheep at baseline and during epidural-induced maternal hypotension at 117-132 (term 145) days of gestation. Uterine artery blood flow velocity waveforms were obtained by Doppler ultrasonography. RESULTS Maternal hypotension decreased Q(UtA) without affecting Q(UA). During hypotension, eight out of 24 sheep demonstrated a retrograde diastolic blood flow velocity waveform pattern in the uterine artery. Maternal systolic, diastolic and mean arterial blood pressures were significantly lower in the retrograde group than in the antegrade group. No statistically significant differences in Q(UtA), Q(UA) and fetal blood gas values were detected between the two groups during hypotension. CONCLUSIONS An acute decrease in uterine artery volume blood flow during maternal hypotension is not compensated by increased placental volume blood flow. A retrograde diastolic blood flow pattern in the uterine artery is related to lower maternal arterial pressures, especially during diastole. A uterine artery retrograde diastolic blood flow pattern does not have any additional detrimental short-term effects on fetal acid-base status.
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Affiliation(s)
- T Kavasmaa
- Department of Anaesthesiology, University of Oulu, Oulu, Finland
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17
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Erkinaro T, Mäkikallio K, Acharya G, Päkkilä M, Kavasmaa T, Huhta JC, Alahuhta S, Räsänen J. Divergent effects of ephedrine and phenylephrine on cardiovascular hemodynamics of near-term fetal sheep exposed to hypoxemia and maternal hypotension. Acta Anaesthesiol Scand 2007; 51:922-8. [PMID: 17488314 DOI: 10.1111/j.1399-6576.2007.01327.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND We hypothesized that the administration of ephedrine and phenylephrine for maternal hypotension modifies cardiovascular hemodynamics in near-term sheep fetuses. METHODS At 115-136 days of gestation, chronically instrumented, anesthetized ewes with either normal placental function or increased placental vascular resistance after placental embolization were randomized to receive boluses of ephedrine (n = 12) or phenylephrine (n = 12) for epidural-induced hypotension after a short period of hypoxemia. Fetal cardiovascular hemodynamics were assessed by Doppler ultrasonography at baseline, during hypotension and after vasopressor treatment. RESULTS During hypotension, fetal PO(2) decreased and proximal branch pulmonary arterial and pulmonary venous vascular impedances increased. Additionally, in the embolized fetuses, the time-velocity integral ratio between the antegrade and retrograde blood flow components of the aortic isthmus decreased. These parameters were restored to baseline conditions by ephedrine but not by phenylephrine. With phenylephrine, weight-indexed left ventricular cardiac output and ejection force decreased in the non-embolized fetuses, and the proportion of isovolumetric contraction time of the total cardiac cycle was elevated in the embolized fetuses. CONCLUSIONS After exposure to hypoxemia and maternal hypotension, ephedrine restored all fetal cardiovascular hemodynamic parameters to baseline. Phenylephrine did not reverse fetal pulmonary vasoconstriction or the relative decrease in the net forward flow through the aortic isthmus observed in fetuses with increased placental vascular resistance. Moreover, fetal left ventricular function was impaired during phenylephrine administration.
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Affiliation(s)
- T Erkinaro
- Department of Anesthesiology, Oulu University Hospital, Oulu, Finland.
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18
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Mäkikallio K, Erkinaro T, Niemi N, Kavasmaa T, Acharya G, Päkkilä M, Räsänen J. Fetal oxygenation and Doppler ultrasonography of cardiovascular hemodynamics in a chronic near-term sheep model. Am J Obstet Gynecol 2006; 194:542-50. [PMID: 16458659 DOI: 10.1016/j.ajog.2005.08.028] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 07/15/2005] [Accepted: 08/11/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE We hypothesized that a decrease in fetal oxygenation without acidemia in a near-term fetal sheep leads to cardiovascular hemodynamic changes that are detectable by Doppler ultrasonography. STUDY DESIGN Twelve ewes and fetuses were instrumented at 112 to 127 days of gestation. After a 5-day recovery period, experiments were performed with general anesthesia. Uterine and placental volume blood flows and fetal arterial and venous blood pressures were measured. Fetal cardiovascular hemodynamics was assessed by Doppler ultrasonography. All the measurements were performed at baseline, during fetal hypo-oxygenation, and at recovery phase. RESULTS A drop in fetal Po2 was related to increased (P < .05) weight-indexed right ventricular and combined cardiac outputs and proximal branch pulmonary artery pulsatility index values. The increase in proximal branch pulmonary artery pulsatility index values correlated (R = .59; P < .05) with the decrease in fetal oxygen saturation. In the aortic isthmus, the time-velocity integral ratio between antegrade and retrograde blood flow components decreased (P < .05) when fetal Po2 dropped. CONCLUSION During decreased fetal oxygenation Doppler ultrasonography demonstrated increased fetal cardiac output and pulmonary arterial vascular impedance and a relative increase in the retrograde blood flow component in the aortic isthmus.
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Affiliation(s)
- Kaarin Mäkikallio
- Department of Obstetrics and Gynecology, University of Oulu, Oulu, Finland.
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19
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Hikasa Y, Saito K, Takase K, Ogasawara S. Clinical, cardiopulmonary, hematological and serum biochemical effects of sevoflurane and isoflurane anesthesia in oxygen under spontaneous breathing in sheep. Small Rumin Res 2000; 36:241-249. [PMID: 10781740 DOI: 10.1016/s0921-4488(99)00121-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Effects of sevoflurane and isoflurane anesthesia in oxygen on clinical, cardiopulmonary, hematological, and serum biochemical findings were compared in sheep breathing spontaneously undergoing minor surgical operations during short-term (60-80min) or long-term (3-4h) anesthesia. All sheep were premedicated with atropine sulfate (0.1mg/kg) intramuscularly, and 10min later, induced to anesthesia by intravenous infusion of sodium thiopental (mean 14.1+/-3.4 S.D. mg/kg). After intubation, they were anesthetized with either isoflurane or sevoflurane in oxygen at a total gas flow rate of 1.5l/min. The results revealed that recovery time with sevoflurane was more rapid than with isoflurane. Respiration rates, tidal volume, minute ventilation and heart rates during sevoflurane anesthesia were similar to those during isoflurane anesthesia. The degree of respiratory acidosis during sevoflurane anesthesia was also similar to that during isoflurane anesthesia. There were no significant differences between sevoflurane and isoflurane anesthesia in hematological and serum biochemical values.
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Affiliation(s)
- Y Hikasa
- Department of Veterinary Internal Medicine, Faculty of Agriculture, Tottori University, 4-101 Koyama-Minami, Tottori-shi, Tottori, Japan
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