Name: fetal echocardiography and pulsed-wave doppler ultrasound in a rabbit model of intrauterine growth restriction
Uploaded: 2013-06-29T14:00:00
Description: Watch this Scientific Journal Video about Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction at JoVE.com

This work is supported by a Hamilton-Fairley NHMRC Fellowship (RH, AL); the Victorian Government's Operational Infrastructure Support Program (RH, EW) and the Marie Curie Industria-Academia Partnership and Pathways grant sponsored by the European Commission (ME, PD). The authors would like to thank Dr. Andre Miyague, Dr. Francesca Russo, Ms. Rosita Kinnart and Mr. Ivan Laermans for their technical expertise in producing this video.

The following experimental protocol is approved by the Animal Ethics Committee, Katholieke Universiteit Leuven, Leuven, Belgium. We followed previously described surgical procedure13 including some methodological changes, especially in anesthesia procedure.
1. Inducing Intrauterine Growth Restriction (IUGR)
<ol>
	<li>Time dated pregnant rabbits (hybrid Dendermonde and New Zealand White) are housed in individual cages on a 12/12 hr light schedule with access to water and standard r...

We have used a previously validated approach of surgically reducing uteroplacental blood flow in a rabbit to produce IUGR13-16 and later examining fetal cardiac function14 to describe microultrasound technology and cardiac function analysis available on the VisualSonics VEVO 2100. The ability to reproduce fetoplacental Doppler changes of human IUGR fetuses in a small animal model and to then allow examination of cardiac function with recently described echocardiography is likely to progress fetal ca...

The burden of cardiovascular disease that results from fetal intrauterine growth restriction (IUGR) cannot be overstated. It is the leading cause of stillbirth after congenital abnormalities.1 IUGR refers to a fetus that fails to reach its growth potential and is commonly a result of placental insufficiency.2 In survivors, cardiovascular ill health is evident across the life span with myocardial dysfunction apparent in infancy and childhood3,4 and subsequent hypertension5, diabetes6, and obesity developing in adult life - all cumulative cardiac risk factors from birth towards premature death from ischemic heart disease.7
Developing animal models to characterize the maternal-fetal communication that establishes IUGR and the subsequent fetal response to reduced substrate availability is necessary if we are to both better understand the pathophysiology of IUGR-related cardiac impairment and to develop cardio-protective strategies to improve fetal and postnatal health. In this regard, many different models across different species have been described.8 IUGR is commonly induced by maternal under nutrition with a low protein diet in rodents,9 surgical ablation or ligation of uterine blood flow in rodents and guinea pigs10 or occlusion of the umbilical artery in sheep.11 However, it is apparent that no model fully recapitulates the human IUGR.12
In this current methodological study, we used a well validated approach of selective uteroplacental vascular interruption in a rabbit13-16 that not only produces fetal cardiovascular responses observed with ultrasound clinically14, but also allows interrogation of fetal cardiac function with novel echocardiography using microultrasound technology of the VisualSonics VEVO 2100. While Doppler ultrasound of fetoplacental vessels remains the cornerstone of current antenatal surveillance of IUGR fetuses17, functional echocardiography is increasingly being utilized to provide new insights into disease pathophysiology and to assess fetal wellbeing.18 Accordingly, here we take these advances from clinical research and describe an animal model that harbors not only this imaging sophistication but also provides the experimental platform to investigate mechanistic pathways and novel therapeutics.

<table border="1">
	<tbody>
 <tr>
 <td>Name of Reagent/Material</td>
 <td>Company</td>
 <td>Catalog Number</td>
 <td>Comments</td>
 </tr>
 <tr>
 <td>Ketamine</td>
 <td>Ceva Sante Animale</td>
 <td></td>
 <td><a href="http://www.ceva.com/en" target="_blank">http://www.ceva.com/en</a></td>
 </tr>
 <tr>
 <td>Xylazine</td>
 <td>Ceva Sante Animale</td>
 <td></td>
 <td><a href="http://www.ceva.com/en" target="_blank">http://www.ceva.com/en</a></td>
 </tr>
 <tr>
 <td>Depot Provera</td>
 <td>Pharmacia Upjohn</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Penicillin G</td>
 <td>Kela Pharma</td>
 <td></td>
 <td><a href="http://www.kela.be" target="_blank">http://www.kela.be</a></td>
 </tr>
 <tr>
 <td >Lidocaine</td>
 <td>B Braun Medical</td>
 <td></td>
 <td><a href="http://www.bbraun.com/" target="_blank">http://www.bbraun.com/</a></td>
 </tr>
 <tr>
 <td>Temgesic</td>
 <td>Schering-Plough</td>
 <td></td>
 <td><a href="http://www.merck-animal-health-usa.com/" target="_blank">http://www.merck-animal-health-usa.com/</a></td>
 </tr>
 <tr>
 <td>Isolurane</td>
 <td>Isoba Vet; Abbott Laboratories Ltd</td>
 <td></td>
 <td><a href="http://www.abbottanimalhealth.com/index.html" target="_blank">http://www.abbottanimalhealth.com/index.html</a></td>
 </tr>
 <tr>
 <td>Ethicon</td>
 <td>Johnson and Johnson</td>
 <td></td>
 <td><a href="http://www.ethiconproducts.co.uk/products/sutures" target="_blank">http://www.ethiconproducts.co.uk/products/sutures</a></td>
 </tr>
 <tr>
 <td>Ethicon</td>
 <td>Johnson and Johnson</td>
 <td></td>
 <td><a href="http://www.ethiconproducts.co.uk/products/sutures" target="_blank">http://www.ethiconproducts.co.uk/products/sutures</a></td>
 </tr>
 <tr>
 <td>Ethicon</td>
 <td>Johnson and Johnson</td>
 <td></td>
 <td><a href="http://www.ethiconproducts.co.uk/products/sutures" target="_blank">http://www.ethiconproducts.co.uk/products/sutures</a></td>
 </tr>
 <tr>
 <td>VEVO 2100</td>
 <td>VisualSonics</td>
 <td>SN100-0032</td>
 <td><a href="http://www.visualsonics.com/" target="_blank">http://www.visualsonics.com/</a></td>
 </tr>
 <tr>
 <td>Aquasonic Gel</td>
 <td>Parker Laboratories</td>
 <td>01 02</td>
 <td><a href="http://www.parkerlabs.com/ultrasound_products.html" target="_blank">http://www.parkerlabs.com/ultrasound_products.html</a></td>
 </tr>
 <tr>
 <td>Nellcor N-20PA Pulse oximeter</td>
 <td>Covidien</td>
 <td></td>
 <td><a href="http://www.nellcor.com/prod/PRODUCT.ASPX?S1=POX&amp;S2=MON&amp;id=282&amp;V" target="_blank">http://www.nellcor.com/prod/PRODUCT.ASPX?S1=POX&amp;S2=MON&amp;id=282&amp;V</a></td>
 </tr>
	 </tbody>
 </table>

fetal echocardiography and pulsed-wave doppler ultrasound in a rabbit model of intrauterine growth restriction

Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ultrasound and fetal echocardiography. Increasingly, these imaging modalities are being employed clinically to examine cardiac function and assess wellbeing in utero, thereby guiding timing of birth decisions. Here, we used a rabbit model of IUGR that allows analysis of cardiac function in a clinically relevant way. Using isoflurane induced anesthesia, IUGR is surgically created at gestational age day 25 by performing a laparotomy, exposing the bicornuate uterus and then ligating 40-50% of uteroplacental vessels supplying each gestational sac in a single uterine horn. The other horn in the rabbit bicornuate uterus serves as internal control fetuses. Then, after recovery at gestational age day 30 (full term), the same rabbit undergoes examination of fetal cardiac function. Anesthesia is induced with ketamine and xylazine intramuscularly, then maintained by a continuous intravenous infusion of ketamine and xylazine to minimize iatrogenic effects on fetal cardiac function. A repeat laparotomy is performed to expose each gestational sac and a microultrasound examination (VisualSonics VEVO 2100) of fetal cardiac function is performed. Placental insufficiency is evident by a raised pulsatility index or an absent or reversed end diastolic flow of the umbilical artery Doppler waveform. The ductus venosus and middle cerebral artery Doppler is then examined. Fetal echocardiography is performed by recording B mode, M mode and flow velocity waveforms in lateral and apical views. Offline calculations determine standard M-mode cardiac variables, tricuspid and mitral annular plane systolic excursion, speckle tracking and strain analysis, modified myocardial performance index and vascular flow velocity waveforms of interest. This small animal model of IUGR therefore affords examination of in utero cardiac function that is consistent with current clinical practice and is therefore useful in a translational research setting.

An asymmetrical growth restricted fetus and placenta from uteroplacental vascular ligation is compared to a normal control fetus and placenta in Figure 1F. Asymmetrical growth is confirmed by reduced neonatal birth weight and increased head circumference:abdominal circumference ratio to controls. Representative results from fetoplacental Doppler studies are shown in Figure 2. A normal low resistance pattern of positive end-diastolic flow in a control fetus is shown. With progressive incr...

Watch this Scientific Journal Video about Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction at JoVE.com

Fetal Echocardiography and Pulsed-wave Doppler Ultrasound in a Rabbit Model of Intrauterine Growth Restriction

We describe examination of fetal cardiac function with contemporary functional fetal echocardiography and fetoplacental Doppler ultrasound using the VisualSonics VEVO 2100 microultrasound in a surgically induced model of intrauterine fetal growth restriction in a rabbit.

Fetal intrauterine growth restriction (IUGR) results in abnormal cardiac function that is apparent antenatally due to advances in fetoplacental Doppler ...

Research

JoVE Journal

Medicine

Murine Echocardiography and Ultrasound Imaging

Rodent models of cardiac pathophysiology represent a valuable research tool to investigate mechanism of disease as well as test new therapeutics.1  ...

Assessing Teratogenic Changes in a Zebrafish Model of Fetal Alcohol Exposure

Fetal alcohol syndrome (FAS) is a severe manifestation of embryonic exposure to ethanol. It presents with characteristic defects to the face and organs, ...

A Novel Surgical Approach for Intratracheal Administration of Bioactive Agents in a Fetal Mouse Model

Prenatal pulmonary delivery of cells, genes or pharmacologic agents could provide the basis for new therapeutic strategies for a variety of genetic and ...

Murine Fetal Echocardiography

Transgenic mice displaying abnormalities in  cardiac development and function represent a powerful tool for the understanding  the molecular mechanisms ...

A Mouse Fetal Skin Model of Scarless Wound Repair

Early in utero, but not in postnatal life, cutaneous wounds undergo regeneration and heal without formation of a scar. Scarless fetal wound healing occurs ...

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. ...

Percutaneous Contrast Echocardiography-guided Intramyocardial Injection and Cell Delivery in a Large Preclinical Model

Cell and gene therapy are exciting and promising strategies for the purpose of cardiac regeneration in the setting of heart failure with reduced ejection ...

A Pleural Effusion Model in Rats by Intratracheal Instillation of Polyacrylate/Nanosilica

Pleural effusion is a prevalent clinical finding of many pulmonary diseases. Having a useful animal pleural effusion model is very important to study ...

Continuous Venous-Arterial Doppler Ultrasound During a Preload Challenge

A preload challenge (PC) is a clinical maneuver that, first, increases the cardiac filling (i.e., preload) and, second, calculates the change in cardiac ...

A Modified Sonographic Algorithm for Image Acquisition in Life-Threatening Emergencies in the Critically Ill Newborn

The use of routine point-of-care ultrasound (POCUS) is increasing in neonatal intensive care units (NICUs), with several centers advocating for 24 h ...