A Surgical Model of Heart Failure with Preserved Ejection Fraction in Tibetan Minipigs
February 18th, 2022
The present protocol describes a step-by-step procedure to establish a minipig model of heart failure with preserved ejection fraction using descending aortic constriction. The methods for evaluating cardiac morphology, histology, and function of this disease model are also presented.
More than half of heart failure cases worldwide are classified as heart failure with preserved blood ejection fraction or HFpEF. This video presents a step by statist procedure to model HFpEF minipigs as well as echocardiography techniques for assessing cardiac function. This model has a single predisposing filter.
There is aortic constriction, induced pressure overload. Hence, the model is helpful for studying a certain type of HFpEF. In addition to surgical technique per operation planning, animal quality control and post-operation animal care are critical steps.
The biochemical tests and electrocardiography help in monitoring animal health and changes in her structure and function. Xiaohui Li, a clinical cardiac surgeon. Weijiang Tan, a trained animal surgeon.
Xiang Li, a trained anesthetist for this operation. Shuang Chen, a trained operating room nurse. And Honghua Chen, a trained operating room nurse will be demonstrating the procedure.
To begin acclimatize the animals to the facility for 14 days before surgery. Prepare the surgical room and devices. Restrain and place the minipig in the right lateral recumbent position on the operating surgery table.
Turn on the heating system to maintain the body temperature of the animal. Perform the echocardiography and collect a two milliliter blood sample. Initiate the ventilation at eight milliliters per kilograms of tidal volume and 30 breaths per minute.
Establish intravenous cannulation using a peripheral intravenous catheter from an ear vein. Then connect the animal to a veterinary monitor. Shave the left thoracic area.
Apply 0.7%iodine and 75%alcohol to aseptically prepare the skin from the scapula to the diaphragm. Place sterile drapes over the surgical area. Mark approximately a 15 centimeter long incision along the fourth intercostal space.
Then make the skin incision using electrocautery. Open the chest using a combination of cautery and blunt dissection of the muscle and connective tissue. Use a rib retractor to spread the ribs.
Locate the thoracic descending aorta segment and determine the constriction site and use two three OTT surgical sutures to loop around the segment twice. Set up pressure measurement units. To determine the degree of constriction, tighten the surgical suture surrounding the descending aorta segment gradually to achieve the desired constriction degree.
Allow the pressure readings to stabilize for 20 minutes and permanently tighten the surgical knots. Use a drainage chest tube to evacuate the air and excess fluids in the chest cavity. Monitor the presence of eye blinking and limb movement of the animal.
Disconnect the ventilator, but leave the endotracheal tube and monitor the presence of spontaneous breathing. Place the animal in a mobile restraint unit with a canvas cover. Shave the left chest of the animal.
Place fingers on the left center of the chest to feel the epical pulse. Apply the ultrasonic gel to the surrounding area. Place the ultrasound system's phased array transducer in the third intercostal space.
Move the transducer toward an anterior or posterior direction and adjust the notch angle. Identify the atria, ventricles and aorta and record the B mode and M mode perasternal long axis images. Next in the parasternal short axis view, identify the interventricular septum, left ventricular posterior wall and papillary muscle, and record the B mode and M mode images.
Use the workstation provided by the manufacturer of the ultrasound system to assess the cardiac structure and function. The cardiac structure and function evaluation showed the displayed B mode and M mode recordings of the perasternal short axis. The ventricular septum thickness increased in the descending aortic constriction hearts, whereas the posterior wall thickness increased and then decreased during the observation period, suggesting the hypertrophic remodeling in the left ventricle of the descending aortic constriction minipigs.
The left ventricular internal dimension at end diastole decreased in weeks four and six, and then gradually increased after week eight, suggesting that the ventricles underwent concentric hypertrophy before dilation. The left ventricular ejection fraction of the model hearts was maintained at more than 50%during the 12 weeks. Compared with sham hearts, enlargement of the descending aortic constriction hearts was observed.
The heart failure marker, cardiac troponin I, was significantly higher at weeks 4, 8 and 12 in the descending aortic constriction group than in the sham group at the corresponding time points. Cardiomyocytes in the atria ventricular septum and ventricles displayed hypertrophy with pignosis. Muscular layers were reduced in endometrial valve and vascular endothelial hyperplasia was observed in the aorta.
Moreover, descending aortic constriction induced extensive fibrosis in the myocardium of the minipigs, accompanied by infiltration of inflammatory cells in the left ventricles, right atrium, and aortic walls. This model is a powerful tool to study tissues damage, fibrosis, inflammation, and concentric dysfunction in pressure overload induced HFpEF.
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Overview
This protocol outlines a method for establishing a minipig model of heart failure with preserved ejection fraction (HFpEF) through descending aortic constriction. It details the evaluation of cardiac morphology, histology, and function in this disease model.
Key Study Components
Area of Science
- Cardiology
- Animal Models
- Heart Failure Research
Background
- HFpEF accounts for over half of heart failure cases globally.
- The minipig model is useful for studying specific types of HFpEF.
- Aortic constriction induces pressure overload, simulating HFpEF conditions.
- Proper surgical technique and animal care are essential for model success.
Purpose of Study
- To develop a reliable minipig model for HFpEF research.
- To assess cardiac function using echocardiography techniques.
- To provide a framework for evaluating cardiac morphology and histology.
Methods Used
- Descending aortic constriction to induce heart failure.
- Echocardiography for assessing cardiac function.
- Evaluation of cardiac morphology and histology.
- Post-operative animal care and quality control measures.
Main Results
- Successful establishment of a minipig model for HFpEF.
- Demonstrated techniques for evaluating cardiac function.
- Insights into the morphological and histological changes in HFpEF.
- Emphasized the importance of surgical precision and animal welfare.
Conclusions
- The minipig model is a valuable tool for HFpEF research.
- Proper methodology ensures reliable results in cardiac studies.
- Future studies can build on this model to explore HFpEF mechanisms.
Frequently Asked Questions
Executive Industry Relevance
Large animal models that recapitulate heart failure with preserved ejection fraction (HFpEF) are critical for translational research and preclinical evaluation of therapeutic strategies. The Tibetan minipig DAC model enables mechanistic de-risking and target validation in a physiologically relevant system, supporting predictive confidence for portfolio advancement. This model addresses a key inflection point in cardiovascular drug discovery by bridging early discovery and preclinical validation.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables interrogation of HFpEF pathophysiology in a large animal system.
- Supports functional target validation through controlled induction of pressure overload.
- Facilitates mechanistic de-risking by modeling fibrosis, inflammation, and hypertrophy.
- Provides a platform for evaluating molecular and cellular disease drivers.
Screening & Assay Development
- Establishes a reproducible in vivo system for downstream biomarker and functional assay development.
- Delivers quantitative echocardiographic and biochemical outputs for assay standardization.
- Enables screening of candidate interventions in a disease-relevant context.
- Supports scalability and cross-study comparability through standardized surgical and imaging protocols.
Translational & Preclinical Research
- Aligns with human HFpEF features, enhancing translational biomarker validation.
- Provides continuity from discovery through preclinical efficacy and safety assessment.
- Enables risk-adjusted advancement decisions based on large animal data.
- Supports evaluation of cardiac remodeling and functional endpoints relevant to clinical translation.
Pipeline & Workflow Integration
This DAC-induced HFpEF model fits between early discovery and preclinical lead validation, enabling hypothesis testing and translational continuity for cardiovascular programs.
- Discovery Biology: Facilitates hypothesis-driven investigation of pressure overload-induced cardiac remodeling and dysfunction.
- Screening: Provides quantitative echocardiographic and biochemical readouts for candidate evaluation.
- Analytics: Supports statistical comparison of cardiac structure, function, and biomarker levels across experimental groups.
- Translational Research: Bridges mechanistic studies and preclinical efficacy testing in a clinically relevant model.
- Enterprise Reuse: Offers a standardized, reusable platform for cardiovascular target and biomarker research.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in HFpEF research.
- Operational Value: Delivers reproducible, scalable, and standardized large animal data for cross-functional teams.
- Strategic Value: Improves go/no-go decision quality and capital efficiency in cardiovascular portfolios.
- Portfolio Impact: Enables risk-adjusted prioritization and advancement of HFpEF therapeutic candidates.
Implementation Considerations
- Requires expertise in large animal surgery, echocardiography, and post-operative care.
- Demands access to veterinary monitoring, imaging, and biochemical analysis infrastructure.
- Necessitates rigorous cross-team standardization of surgical and analytical protocols.
- Adaptation to other large animal species may require protocol optimization.
- Model is specific to pressure overload-induced HFpEF and may not capture all disease subtypes.
