The Influence of the Maternal Heart Rate on the Uterine Artery Pulsatility Index in the Pregnant Ewe

Ochi, Hiroshi; Matsubara, Keiichi; Kusanagi, Yasuki; Furutani, Kouichi; Katayama, Tohru; M, Ito

doi:10.1159/000010066

Cited by 7 publications

(6 citation statements)

References 9 publications

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“…Therefore, the most likely explanation for increased DV pulsatility is that the fetal heart rate was significantly lower in the recovery phase, as a negative correlation is known to exist between heart rate and PI of vessels. 27 Our study has some limitations. The surgical procedures may constitute a significant stress on the sheep fetuses, and it may be argued that the conditions are quite different from human fetuses exposed to hypoxemia.…”

Section: Discussionmentioning

confidence: 89%

Effect of Sildenafil on Pulmonary Circulation and Cardiovascular Function in Near-Term Fetal Sheep During Hypoxemia

et al. 2019

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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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Section: Discussionmentioning

confidence: 89%

Effect of Sildenafil on Pulmonary Circulation and Cardiovascular Function in Near-Term Fetal Sheep During Hypoxemia

et al. 2019

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“…In a previous study, we investigated the influence of the maternal heart rate on the uterine artery PI in pregnant ewes5. We used an external pacemaker to alter the heart rate, and examined the effect this had on uterine artery blood flow.…”

Section: Discussionmentioning

confidence: 99%

“…Subsequently, we calculated normalized PI, and evaluated the effect of normalization. For normalization we used a formula that was derived from our previous study5 in which we investigated the influence of the maternal heart rate on the uterine artery PI in pregnant ewes using a pacemaker. Uterine blood flow velocity waveforms varied with the heart rate, and this was reflected in a decrease in uterine artery PI.…”

Section: Methodsmentioning

confidence: 99%

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Clinical significance of normalization of uterine artery pulsatility index with maternal heart rate for the evaluation of uterine circulation in pregnancy‐induced hypertension

Ochi

Kusanagi

Katayama

et al. 2003

Ultrasound in Obstet & Gyne

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“…As reported by Ochi et al , HR and uterine artery PI are inversely correlated; to correct for the influence of HR on the uterine artery PI we normalized PI for HR using the following formula derived from previous studies34, 35: normalized PI (NPI) = 0.693/(0.895 − 0.00241 × HR) × PI.…”

Section: Methodsmentioning

confidence: 99%

Acute efficacy of a sublingual dose of nifedipine on uterine arterial blood flow: preliminary data in prematurely menopausal women

Huissoud

Hadj

Bied-Damon

et al. 2004

Ultrasound in Obstet & Gyne

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The Influence of the Maternal Heart Rate on the Uterine Artery Pulsatility Index in the Pregnant Ewe

Cited by 7 publications

References 9 publications

Effect of Sildenafil on Pulmonary Circulation and Cardiovascular Function in Near-Term Fetal Sheep During Hypoxemia

Effect of Sildenafil on Pulmonary Circulation and Cardiovascular Function in Near-Term Fetal Sheep During Hypoxemia

Clinical significance of normalization of uterine artery pulsatility index with maternal heart rate for the evaluation of uterine circulation in pregnancy‐induced hypertension

Acute efficacy of a sublingual dose of nifedipine on uterine arterial blood flow: preliminary data in prematurely menopausal women

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