Name: Confirmation of Established Abdominal Arteriovenous Fistula by Ultrasound and Volume Overload by Echocardiography in Postnatal Mice
Uploaded: 2023-06-09T14:30:00
Description: Watch this Scientific Journal Video about Confirmation of Established Abdominal Arteriovenous Fistula by Ultrasound and Volume Overload by Echocardiography in Postnatal Mice at JoVE.com

confirmation of established abdominal arteriovenous fistula by ultrasound and volume overload by echocardiography in postnatal mice

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

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.

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.

Watch this Scientific Journal Video about Confirmation of Established Abdominal Arteriovenous Fistula by Ultrasound and Volume Overload by Echocardiography in Postnatal Mice at JoVE.com

Confirmation of Established Abdominal Arteriovenous Fistula by Ultrasound and Volume Overload by Echocardiography in Postnatal Mice  

To confirm the fistula by ultrasound, begin by taping down the anesthetized mouse in a supine position on the warm platform. Then connect the mouse to an ECG monitor with pre-warmed ultrasound gel. Use hair removal cream to depilate the chest and abdominal skin.Place a 24 megahertz transducer on the mid-abdominal line and rotate the transducer marker to the mouse head. Now, move the platform down to the left or right side of the mouse and use B-mode and Color Doppler mode to visualize the long axis view of the vessels and blood signals. Use the Pulsed-Wave Doppler mode to measure the blood flow velocity of the AA, IVC, and fistula to confirm arteriovenous fistula patency.To confirm ventricular volume overload, move the tail end of the platform downward. Then place the transducer on the chest rotating the marker to the right shoulder of the mouse. Use the B-mode and the Color Doppler modes to visualize the modified parasternal long axis view of the pulmonary artery or PA.Now using the Pulsed Wave Doppler mode measure the blood flow signals in the PA, including the velocity, time integral, PA valve diameter, pulmonary arterial acceleration, and right ventricular ejection time.Use the mean of three consecutive measurements in each case. The postnatal VO mice showed an acceptable perioperative survival rate in the early postoperative period. The AVF patency rates were 70%at one and two weeks, 46.7%at one month, and 40%at two months postoperatively.Both the PA valve diameter and the right ventricular stroke volume increased within two months. The PA velocity time integral was relatively higher in the VO group within two weeks postoperatively, but declined thereafter. The PA flow patterns changed with decreasing PA acceleration.The right ventricular systolic pressure significantly increased with pulmonary regurgitation two months after surgery. Microscopic analysis showed a significantly enlarged right ventricle of the VO group after AVF, while histological staining showed a thickened RV3 wall and enlarged RV cavity.

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Research

JoVE Journal

Medicine

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.

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 ...

Abdominal Arteriovenous Fistula Surgery in Postnatal Mice to Establish RV Volume Overload Model

Begin by testing for pinch reflexes on the anesthetized mouse pup's tail to confirm the depth of anesthesia. Next, disinfect the skin with three alternating rounds of Betadine and 70%ethanol using sterile cotton swabs. Cut the abdominal wall and peritoneum from the lower abdomen to the subxiphoid to fully expose the peritoneal cavity.Use cotton swabs to gently pull away the gastrointestinal tract and the bladder to visualize the vertical abdominal aorta or AA and the inferior vena cava or IVC under the retroperitoneum. After rotating the operating table 90 degrees counterclockwise, adjust the microscope magnification to view the two horizontal vessels clearly. Using an 11-0 suture needle having a 0.7 millimeter diameter, puncture the fistula obliquely from the AA into the IVC.Verify the successful puncture by observing the swelling and mixing of the venous and arterial blood in the IVC. Press the bleeding point with dry cotton swabs for 15 seconds to compress it rapidly. Immediately place the stomach, intestines and bladder back into the abdominal cavity to promote hemostatic compression.Make a blanket stitch on the abdominal wall and peritoneum using a 9-0 suture thread, then place the mouse on a warm pad.