This work was supported by the National Science Foundation of China (no. 82200309) and the Innovation Project of Distinguished Medical Team in Ningbo (no. 2022020405)

All of the procedures presented here conformed to the principles outlined in the Declaration of Helsinki and were approved by the Animal Welfare and Human Studies Committee at Shanghai Children&#39;s Medical Center (SCMC-LAWEC-2023-003). C57BL/6 mice pups (P7, males, 3-4 g) were used for the present study. The animals were obtained from a commercial source (see Table of Materials). The mice pups and their nursing mothers (pups:mothers = 6:1 in a single cage) were kept under specific-pathogen-free laborat...

Modified Arteriovenous Fistula Surgery to Establish the RV Volume Overload Mouse Model

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Previously, the classic RV VO model was created using valve regurgitation21; however, compared to AVF, open-heart valve surgery may require more sophisticated techniques and may be associated with significantly higher mortality, particularly in postnatal mice. As animal studies have shown that the same effect of VO has been achieved by AVF22, modified abdominal fistula surgery with less trauma was used in this study.
Certain factors were consider...

Right ventricular (RV) volume overload (VO) is common in children with congenital heart disease (CHD), which leads to pathological myocardial remodeling and a poor long-term prognosis1,2,3. An in-depth understanding of RV remodeling and related early targeted interventions is essential for a good outcome in children with CHD. There are several differences in the molecular structures, physiological functions, and responses to stimuli in the hearts of adults and children1,4,5,6. For example, under the influence of pressure overload, cardiomyocyte proliferation is the main response in neonatal hearts, whereas fibrosis occurs in adult hearts5,6. In addition, many effective drugs in treating heart failure in adults have no therapeutic effect on heart failure in children, and may even cause further damage7,8. Therefore, conclusions drawn from adult animals cannot be directly applied to young animals.
The arteriovenous fistula (AVF) model has been used to induce chronic heart VO and corresponding cardiac dysfunction for decades in adult animals of different species9,10,11,12,13. However, little is known about the model in postnatal mice. In our previous studies, a VO postnatal mouse model was successfully generated by the creation of an abdominal AVF. The changed RV developmental track in the postnatal heart was also demonstrated14,15,16,17.
To explore the underlying modified surgical process and characteristics of the present model, a detailed protocol is presented; the model is evaluated for 3 months in this study.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>70% Ethanol</td>
			<td>Tiandz,Chia</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ACETAMINOPHEN Oral Solution</td>
			<td>VistaPharm, Inc. Largo, FL 33771, USA</td>
			<td>NDC 66689-054-01</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia machine</td>
			<td>RWD Life Science,China</td>
			<td>R550IP</td>
			<td></td>
		</tr>
		<tr>
			<td>Anesthesia mask</td>
			<td>RWD Life Science,China</td>
			<td>68680</td>
			<td></td>
		</tr>
		<tr>
			<td>C57BL/6 mice</td>
			<td>Xipu&#8217;er-bikai Experimental Animal Co., Ltd (Shanghai, China)</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hair removal cream</td>
			<td>Veet, France</td>
			<td>VT-200</td>
			<td></td>
		</tr>
		<tr>
			<td>Hematoxylin and eosin Kit&#160;</td>
			<td>Beyotime biotech&#160;</td>
			<td>C0105M&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>RWD Life Science,China</td>
			<td>R510-22-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>&#160;Yuyan Instruments, China</td>
			<td>SM-301</td>
			<td></td>
		</tr>
		<tr>
			<td>Surgical suture needles</td>
			<td>NINGBO MEDICAL NEEDLE CO.,LTD, China</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Thermostatic heating platform</td>
			<td>Qingdao Juchuang Environmental Protection Group Co., Ltd, China</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasound device</td>
			<td>FUJIFILM VisualSonics, Inc.</td>
			<td>Vevo 2100</td>
			<td>Image modes includes B-Mode, Color Doppler Mode and Pulsed Wave Doppler Mode</td>
		</tr>
		<tr>
			<td>Ultrasound gel</td>
			<td>Parker Laboratories,United States</td>
			<td>REF 01-08</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasound transducer</td>
			<td>FUJIFILM VisualSonics, Inc.</td>
			<td>MS 400</td>
			<td></td>
		</tr>
	</tbody>
</table>

establishment and confirmation of a postnatal right ventricular volume overload mouse model

Right ventricular (RV) volume overload (VO) is common in children with congenital heart disease. In view of distinct developmental stages,the RV myocardium may respond differently to VO in children compared to adults. The present study aims to establish a postnatal RV VO model in mice using a modified abdominal arteriovenous fistula. To confirm the creation of VO and the following morphological and hemodynamic changes of the RV, abdominal ultrasound, echocardiography, and histochemical staining were performed for 3 months. As a result, the procedure in postnatal mice showed an acceptable survival and fistula success rate. In VO mice, the RV cavity was enlarged with a thickened free wall, and the stroke volume was increased by about 30%-40% within 2 months after surgery. Thereafter, the RV systolic pressure increased, corresponding pulmonary valve regurgitation was observed, and small pulmonary artery remodeling appeared. In conclusion, modified arteriovenous fistula (AVF) surgery is feasible to establish the RV VO model in postnatal mice. Considering the probability of fistula closure and elevated pulmonary artery resistance, abdominal ultrasound and echocardiography must be performed to confirm the model status before application.

Author Spotlight: Establishment and Confirmation of a Postnatal Right Ventricular Volume Overload Mouse Model  

Establishment and Confirmation of a Postnatal Right Ventricular Volume Overload Mouse Model

Our research scope is the congenital heart disease and heart regeneration. We are trying to understand how volume or pressure overload affects the postnatal heart and lung development, including cardiomyocyte proliferation and maturation. We have developed various types of postnatal mouse or rat models of congenital heart disease.For example, ventricular overload, pressure overload, and the reduced pulmonary blood flow. These models are fascinating and would advance our understanding of pediatric congenital heart disease. For decades, the AVF model has been used to induce chronic heart VO in adult animals.However, little is known about the model in postnatal mice. This study generated a VO postnatal mouse model by creating an abdominal AVF. The morphological and the hemodynamic changes of the right ventricle are demonstrated.

Survival rate and AVF patency within 3 months 
A total of 30 (75%) mice in the VO group and 19 (95%) mice in the sham group survived the AVF surgery (Figure 4A). In the VO group, eight mice died within 1 day after surgery due to excessive bleeding (n = 5) or cannibalization (n = 3), whereas two mice died of unknown causes at 1 month.
Of the surviving VO mice (n = 30), ultrasound confirmed the successful establishment of fistulas in 21 mice po...

Watch this Scientific Journal Video about Establishment and Confirmation of a Postnatal Right Ventricular Volume Overload Mouse Model at JoVE.com

This protocol presents the establishment and confirmation of a postnatal right ventricular volume overload (VO) model in mice with abdominal arteriovenous fistula (AVF), which can be applied to investigate how VO contributes to postnatal heart development.

Right ventricular (RV) volume overload (VO) is common in children with congenital heart disease. In view of distinct developmental stages,the RV ...

establishment-confirmation-postnatal-right-ventricular-volume