2.50
Hdl Handle:
http://hdl.handle.net/10755/159225
Type:
Presentation
Title:
Does Increased Blood Volume “Stretch” the Heart During Pregnancy?
Abstract:
Does Increased Blood Volume “Stretch” the Heart During Pregnancy?
Conference Sponsor:Midwest Nursing Research Society
Conference Year:2004
Author:Hines, Tina, PhD, RN
Title:Professor
Contact Address:SON, 2220 Holmes St, Kansas City, MO, 64108, USA
Co-Authors:Sarang Abhyankar, MS, Research Associate; Jessica Veeh, BS, Research Associate
Blood volume expands significantly during pregnancy. Yet, studies have shown that incoming signals from volume-sensitive atrial stretch receptors to the brain are reduced in pregnancy, in spite of marked increases in atrial pressure in response to volume expansion. Whether an alteration in atrial size could be responsible for the reduction in receptor firing has not been determined. To test the hypothesis that the atrium stretches less during volume expansion in the gravid rat, we compared the effects of blood volume expansion on right atrial pressure (RAP) and right atrial dimension (RAD) in pregnant and nonpregnant rats. Animals were anesthetized (Inactin, 100 mg/kg ip), artificially ventilated and a catheter was inserted into the right atrium for measuring pressure. Through a parasternal incision, the right atrium was isolated and the pericardium cleared. Sonomicrometer crystals (0.7 mm) were glued to the medial and lateral surfaces of the right atrium. RAD was determined from the transit time of an ultrasonic wave between the two crystals. Pressure and dimension were recorded for 30sec at baseline and during progressive intravenous blood volume expansion with 6% dextran (20%, 40% and 60% of initial blood volume, determined by dye dilution). Baseline RAP was not different in the two groups (P=2.82±0.4; V=3.2t±0.6mmHg); however, basal RAD was significantly higher (4.36±0.66 vs. 3.36±0.48mm) in pregnant vs. nonpregnant rats, reflecting the expanded blood volume (P=28.6±0.7; V=19.5±0.8ml). In spite of increased resting diameter in pregnant rats, the slope of the relationship between RAD and RAP during exogenous volume expansion was similar in the two groups. Our findings suggest that RAD is augmented by the significant volume expansion of pregnancy, but that the change in dimension during additional volume loads is similar to that in nonpregnant animals. Thus, alterations in right atrial stretch during pregnancy probably do not explain reduced activity in volume-sensitive receptors.
Repository Posting Date:
26-Oct-2011
Date of Publication:
17-Oct-2011
Sponsors:
Midwest Nursing Research Society

Full metadata record

DC FieldValue Language
dc.typePresentationen_GB
dc.titleDoes Increased Blood Volume “Stretch” the Heart During Pregnancy?en_GB
dc.identifier.urihttp://hdl.handle.net/10755/159225-
dc.description.abstract<table><tr><td colspan="2" class="item-title">Does Increased Blood Volume &ldquo;Stretch&rdquo; the Heart During Pregnancy? </td></tr><tr class="item-sponsor"><td class="label">Conference Sponsor:</td><td class="value">Midwest Nursing Research Society</td></tr><tr class="item-year"><td class="label">Conference Year:</td><td class="value">2004</td></tr><tr class="item-author"><td class="label">Author:</td><td class="value">Hines, Tina, PhD, RN</td></tr><tr class="item-author-title"><td class="label">Title:</td><td class="value">Professor</td></tr><tr class="item-address"><td class="label">Contact Address:</td><td class="value">SON, 2220 Holmes St, Kansas City, MO, 64108, USA</td></tr><tr class="item-co-authors"><td class="label">Co-Authors:</td><td class="value">Sarang Abhyankar, MS, Research Associate; Jessica Veeh, BS, Research Associate </td></tr><tr><td colspan="2" class="item-abstract">Blood volume expands significantly during pregnancy. Yet, studies have shown that incoming signals from volume-sensitive atrial stretch receptors to the brain are reduced in pregnancy, in spite of marked increases in atrial pressure in response to volume expansion. Whether an alteration in atrial size could be responsible for the reduction in receptor firing has not been determined. To test the hypothesis that the atrium stretches less during volume expansion in the gravid rat, we compared the effects of blood volume expansion on right atrial pressure (RAP) and right atrial dimension (RAD) in pregnant and nonpregnant rats. Animals were anesthetized (Inactin, 100 mg/kg ip), artificially ventilated and a catheter was inserted into the right atrium for measuring pressure. Through a parasternal incision, the right atrium was isolated and the pericardium cleared. Sonomicrometer crystals (0.7 mm) were glued to the medial and lateral surfaces of the right atrium. RAD was determined from the transit time of an ultrasonic wave between the two crystals. Pressure and dimension were recorded for 30sec at baseline and during progressive intravenous blood volume expansion with 6% dextran (20%, 40% and 60% of initial blood volume, determined by dye dilution). Baseline RAP was not different in the two groups (P=2.82&plusmn;0.4; V=3.2t&plusmn;0.6mmHg); however, basal RAD was significantly higher (4.36&plusmn;0.66 vs. 3.36&plusmn;0.48mm) in pregnant vs. nonpregnant rats, reflecting the expanded blood volume (P=28.6&plusmn;0.7; V=19.5&plusmn;0.8ml). In spite of increased resting diameter in pregnant rats, the slope of the relationship between RAD and RAP during exogenous volume expansion was similar in the two groups. Our findings suggest that RAD is augmented by the significant volume expansion of pregnancy, but that the change in dimension during additional volume loads is similar to that in nonpregnant animals. Thus, alterations in right atrial stretch during pregnancy probably do not explain reduced activity in volume-sensitive receptors. </td></tr></table>en_GB
dc.date.available2011-10-26T21:49:17Z-
dc.date.issued2011-10-17en_GB
dc.date.accessioned2011-10-26T21:49:17Z-
dc.description.sponsorshipMidwest Nursing Research Societyen_GB
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