Structured Exercise Regimen in Pulmonary Hypertension-Right Ventricular Failure in an Ovine Model
May 5th, 2026
This manuscript describes the structured exercise regimen developed to study the effects of exercise on the pathophysiology of pulmonary hypertension-right ventricular heart failure in an ovine model.
We are studying the effects of exercise on the pathophysiology of pulmonary hypertension-right ventricular failure in an ovine model. Exercise effects in pulmonary hypertension right ventricular failure is poorly characterized due to limited tolerance and risk of cardiopulmonary decompensation. However, this protocol enables controlled assessment.
To begin, collect the required reagents and set up the workspace for the experiment. Take three normal saline flushes. Remove one milliliter from each.
And add one milliliter of heparin solution containing 1, 000 units to each syringe. Prepare two 10 milliliter syringes, one for waste and one for blood collection, and five one milliliter syringes for blood gas collection. Using a five milliliter syringe, draw up five milliliters of heparin solution containing 5, 000 units heparin for locking the right ventricular or RV line.
Reconstitute two milligrams of alteplase with 2.2 milliliters of sterile water for use if needed. Obtain one one milliliter syringe and one five milliliter syringe and fill both with hypertonic saline using a 20 to 22 gauge needle. Obtain a pressure transducer and connect the female lure end of pressure tubing to the male lure end of the transducer.
Confirm that the transducer's bottom lure end is capped. Connect the tubing to a three-way stopcock and attach a 22 gauge Huber needle. Flush the line with hypertonic saline until fluid exits the needle.
Then adjust the stopcock to lock toward the needle and away from the blue cap to close the access to the cuff. Remove two milliliters of normal saline from a one liter bag and replace it with two milliliters of heparin solution containing 2, 000 units of heparin. Place the saline bag inside a pressure bag, then insert it into an access bag using an intravenous spike.
Hang the pressure bag approximately two meters above the ground. And turn the three-way stopcock on the pressure bag so that the handle is perpendicular to the tubing. Inflate the bag with the hand pump until the pressure indicator turns green at approximately 250 millimeters of mercury.
Turn the three-way stopcock towards the bag to maintain pressure. Connect the male end of the intravenous line to the female end of the transducer. Next, connect the female lure end of the pressure tubing to the male end of the transducer.
And then attach the male end of the tubing to the female lure end of the stopcock. After attaching a 22 gauge Huber needle to the male end of the three-way stopcock, open the heparin bag and flush the intravenous line until heparinized saline exits the hooper needle. Turn the three-way stopcock toward the Huber needle to lock it.
Use a sheep model of pulmonary hypertension RV failure, instrumented with a PA cuff and an RV pressure port. Following one week of postoperative recovery, transport the treadmill acclimatized sheep to the exercise room for testing. Place a halter on the sheep and use it to lead the animal onto the treadmill, positioning it near the front with its four legs resting on a small crate.
Palpate the ports and clean the skin with alcohol wipes. Use a Huber needle to access the PA port. After opening lab chart homepage, select New, click on set up, select devices and channels.
Set the number of channels to four and rename channel one to four as PA cuff pressure, RV pressure, RV systolic pressure and heart rate. Select cyclic measurements. Go to source and select channel two RV pressure, measurement to maximum and click OK.Repeat process for channel four heart rate, but change measurement to rate.
For channel one and two, confirm that no calculation is selected. Ensure correct access orientation with the PA port positioned closer to the head and the RV port positioned closer to the tail. Position transducers between the sheep and computer at the heart level and connect both pressure transducers to the interface cable.
Once the transducers are zeroed and calibrated, click start to begin recording the RV and PA cuff pressure wave forms at 400 hertz. Turn the stopcock upward to transduce the PA cuff pressure wave form. Then turn the stopcock off toward the sheep to close the waveform.
Place one heparin flush on the three-way stopcock for the RV line and flush the entire line into the RV port. Gently draw back on the syringe until dark blood returns. Turn the stopcock off toward the transducer.
First, use an empty 10 milliliter syringe to draw 10 milliliters of RV blood. Then use a one milliliter syringe to draw 0.2 to 0.4 milliliters of RV blood as the sample. Turn the stop to the upward position.
Pull the blue tab on the RV pressure transducer to open the valve and continue flushing until the line is clear of blood. Start the first exercise speed by setting the treadmill knob to 30, corresponding to 0.46 meters per second and maintain for 10 minutes. Open the PA cuff line periodically during the 10 minute interval to transduce PA cuff pressure.
Near the end of the 10 minute interval, obtain blood gas as demonstrated previously. Repeat the blood sampling, line flushing, and the exercise steps at treadmill settings 40, 50, 30, and zero. Use one milliliter of hypertonic saline to inflate the cuff to 150 to 200 millimeters of mercury.
Transduce RV pressure for a few minutes after inflation to ensure tolerance. Mixed venous oxygen saturation remained relatively stable at maximum treadmill speed from week one to week eight. RV systolic pressure increased from week one to week eight.
The distance traveled during exercise increased from week one to week eight despite the PA cuff pressure increasing to approximately 777 millimeters of mercury by week eight. At the selected treadmill speeds, mixed venous oxygen saturation decreased, and RV systolic pressure increased as exercise speed increased. This protocol allows us to measure hemodynamic values in real time while exercising.
A key challenge in this protocol is maintaining port access or exercise. In particular, maintaining PA cuff pressure. One parameter we hope to measure in greater detail in the future is oxygen consumption during exercise and recovery.
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Overview
This study investigates the physiological adaptations to exercise in a large animal model of chronic pulmonary hypertension-induced right ventricular failure (PH-RVF). Using an ovine (sheep) model, researchers implemented a structured exercise regimen to assess the effects of increased right ventricular afterload and the potential for adaptive responses during progressive disease.
Key Study Components
Area of Science
- Cardiovascular physiology
- Pulmonary hypertension research
- Exercise physiology
- Large animal models
Background
- Right heart failure (RHF) is a major complication of pulmonary hypertension (PH).
- Understanding exercise-induced stress responses in PH-RVF is critical for developing therapeutic strategies.
- Large animal models, such as sheep, provide translational insights into human disease.
- Previous models have not fully characterized exercise responses in PH-RVF.
Purpose of Study
- To characterize the physiological effects of exercise in a chronic PH-RVF ovine model.
- To determine whether exercise induces adaptive or maladaptive responses under increased right ventricular afterload.
- To enable future complex studies of exercise physiology in PH-RVF.
Methods Used
- Eight Dorset cross sheep underwent left pulmonary artery ligation and progressive main pulmonary artery occlusion using an inflatable cuff.
- Subcutaneous ports allowed repeated access to the cuff and right ventricular pressure lines.
- Weekly exercise regimens were performed over eight weeks, including working and recovery speeds.
- Hemodynamic measurements and right ventricular blood gases were collected during exercise and after induced increases in afterload.
Main Results
- Mixed venous oxygen saturation (SvO2) remained stable from week 1 to week 8 despite increased right ventricular systolic pressure (RVSP).
- RVSP increased from 78 ± 8 mmHg to 96 ± 8 mmHg over the study period.
- Distance traveled during exercise increased from 1390 ± 297 m to 1834 ± 189 m, even as pulmonary artery cuff pressure was raised to 777 ± 98 mmHg.
- Findings suggest exercise may promote adaptive compensation in PH-RVF despite increased afterload.
Conclusions
- The ovine PH-RVF model with exercise regimen provides novel insights into adaptive responses to exercise under chronic right ventricular stress.
- Exercise may facilitate compensation and improved functional capacity in PH-RVF.
- This model enables further investigation into exercise physiology and potential therapies for PH-RVF.
Frequently Asked Questions
Executive Industry Relevance
Understanding adaptive responses to exercise in pulmonary hypertension-induced right ventricular failure (PH-RVF) is critical for translational target validation and mechanistic de-risking in cardiopulmonary drug discovery. This ovine model with structured exercise regimens enables quantitative assessment of physiological adaptation under progressive right ventricular afterload, supporting predictive confidence for preclinical candidate selection. The approach informs early-stage portfolio decisions by clarifying disease-relevant compensatory mechanisms in a large animal system.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables interrogation of adaptive versus maladaptive responses in PH-RVF under exercise stress.
- Supports mechanistic de-risking by quantifying right ventricular compensation to increased afterload.
- Provides functional target validation in a disease-relevant large animal model.
Screening & Assay Development
- Establishes reproducible physiological endpoints such as SvO2 and RVSP for downstream screening workflows.
- Facilitates standardization of exercise-induced stress protocols for comparative compound evaluation.
- Enables quantitative measurement of functional capacity changes over time.
Translational & Preclinical Research
- Aligns with translational biomarker development by tracking hemodynamic and oxygenation parameters.
- Provides continuity from discovery through preclinical validation in a model mimicking human PH-RVF.
- Supports risk-adjusted advancement by revealing compensatory limits under chronic stress.
Pipeline & Workflow Integration
This structured exercise regimen positions the ovine PH-RVF model as a bridge from early discovery to preclinical validation, enabling hypothesis testing and functional endpoint measurement across the R&D continuum.
- Discovery Biology: Quantifies adaptive physiological responses to increased afterload, clarifying disease mechanisms.
- Screening: Delivers standardized, reproducible endpoints for evaluating intervention effects.
- Analytics: Provides quantitative outputs such as SvO2, RVSP, and exercise distance for robust statistical comparison.
- Translational Research: Aligns large animal findings with human disease features for biomarker and therapeutic validation.
- Enterprise Reuse: Establishes a reusable platform for future cardiopulmonary intervention studies.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in PH-RVF research.
- Operational Value: Enables standardized, scalable, and reproducible exercise protocols in large animal models.
- Strategic Value: Improves go/no-go decision-making and capital allocation by clarifying adaptive capacity.
- Portfolio Impact: Supports risk-adjusted prioritization of cardiopulmonary assets based on translational relevance.
Implementation Considerations
- Requires expertise in large animal cardiopulmonary physiology and exercise testing.
- Demands specialized instrumentation for hemodynamic monitoring and blood gas analysis.
- Necessitates cross-team standardization of exercise and measurement protocols.
- Adaptation to other species or disease models may require protocol optimization.
- Practical limitations include resource intensity and model-specific physiological constraints.