Name: Structured Exercise Regimen in Pulmonary Hypertension-Right Ventricular Failure in an Ovine Model (Video) | JoVE Journal
Uploaded: 2026-05-05T13:20:00.000+00:00
Duration: 8 min 33 s
Description: Learn structured exercise assessment in pulmonary hypertension-right ventricular failure using an ovine model. This method enables controlled hemodynamic monitoring during progressive disease to study adaptive physiological responses.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

This work was funded by the following institutions and awards: National Institutes of Health R01HL171577, National Institute of General Medical Sciences of the NIH grant T32 GM007347, National Institutes of Health grant T32 HL160508, Vanderbilt Faculty Research Scholar Award, American Heart Association Second Century Early Faculty Independence Award 24SCEFIA1255079, Vanderbilt University Medical Center Cardiothoracic Research Fund, Vanderbilt University Medical Center Mrs. Shelley F. Kleiner and Dr. Fredric Kleiner Fund, Vanderbilt University Medical Center Ms. Dorothy Thomas Research Fund, and the Vanderbilt University Medical Center David M. Livingston Lung Transplant Memorial Fund. Additionally, this work would not have been possible without the Vanderbilt University Animal Care and Use Program and the staff of the S.R. Light Laboratory: Jamie Adcock, Susan Fultz, Azia Tanks, and Eiman Barsoum for their technical support.

The Institutional Animal Care and Use Committee at Vanderbilt University Medical Center approved the following protocol. The described procedures were conducted in accordance with the U.S. National Research Council&#8217;s Guide for the Care and Use of Laboratory Animals9. All sheep were Dorset cross species, female, weighed 55&#8211;65 kg, and were between 1 and 2 years of age. See Figure 1 for the full regimen timeline and exercise session protocol.
1. Treadmill acclimation
<ol>
	<li>After appropriate in-house quarantine and prior to surgery, begin treadmill acclimation.</li>
	<li>Transfer sheep to the exercise room via transport cage.</li>
	<li>Place the halter on the sheep and gently lead the sheep onto the treadmill.</li>
	<li>After the sheep is comfortable, have the sheep place its front legs on the treadmill crate and tie the halter to the front of the treadmill.</li>
	<li>Turn the treadmill on, turn the speed dial to its lowest position of 10, and incentivize sheep with animal-approved food.</li>
	<li>As the treadmill runs, only the sheep&#8217;s back legs should be moving as the front legs are resting on the treadmill crate (Supplementary Video 1).</li>
	<li>After a minute of walking, turn the treadmill off. Repeat turning the treadmill on and walking the sheep for a minute, and increase the speed to 30.</li>
	<li>Repeat steps 1.2&#8211;1.7 two to three times on separate days over the week before surgery. 
	NOTE: Exclude the animals that show signs of severe distress or agitation during the acclimation period.</li>
</ol>
2. Surgical model to initiate the PH-RVF model
<ol>
	<li>Refer to our previous publication that provides details about this surgery, as well as the regular maintenance and titration of the PA cuff8. Nevertheless, this protocol includes the key steps in this first surgery so that the reader can better contextualize them during exercise. 
	NOTE: Anesthesia and analgesia are provided according to the previous publication describing the surgical details, and follow the institutional guidelines.</li>
	<li>Surgical exposure
	<ol>
		<li>Perform a mini left anterior thoracotomy.</li>
		<li>Retract the left&#160;lung and incise the pericardium longitudinally to expose the key structures: the right ventricle and pulmonary artery.</li>
	</ol>
	</li>
	<li>LPA ligation and MPA occluder placement
	<ol>
		<li>Dissect around the main PA and isolate it.</li>
		<li>Follow the main PA up to the bifurcation to expose the LPA. Then, isolate and ligate the LPA with umbilical tape.</li>
		<li>Place the heavy-duty silicon vascular occluder and perivascular flow probes around the MPA. This occluder is also referred to as the PA cuff.</li>
	</ol>
	</li>
	<li>RV pressure line
	<ol>
		<li>Follow the MPA artery down the RV outflow tract free wall to locate the RV.</li>
		<li>Select a location where a pressure line can be secured in the middle of the RV. This line will be used for transducing RV pressures and taking blood gas samples. 
		&#8203;NOTE: The blood gas taken from the RV will serve as a surrogate mixed venous gas. While blood from the PA is true mixed venous blood, blood from the RV is also a mixture of blood from the systemic circulation and the coronary sinus. In the absence of intracardiac shunting, the difference in SvO2 from a PA or RV source is negligible10,11.</li>
	</ol>
	</li>
	<li>Port tunneling
	<ol>
		<li>Bring the RV pressure and PA occluder lines through through one intercostal space below the incision and tunnel in the subcutaneous layer to the left dorsum of the sheep.</li>
		<li>Connect both lines to two separate ports and secure the ports under a layer of subcutaneous tissue. The PA port will be closer to the head&#160;and the RV port closer to the tail.</li>
	</ol>
	</li>
</ol>
3. Postoperative recovery
<ol>
	<li>Allow the sheep to recover for 1 week postoperatively with appropriate pain management and antibiotics per protocol.</li>
	<li>Once the sheep recovers appropriately, proceed forward with the first exercise session.</li>
</ol>
4. Set up for exercise session and cuff check
 
NOTE: Prepare all the materials aseptically.
<ol>
	<li>Make heparin flushes that will be needed to power flush the RV line.
	<ol>
		<li>Acquire 3 normal saline flushes.</li>
		<li>Remove 1 mL of normal saline from flushes.</li>
		<li>Add 1 mL of heparin (1000 units) to syringes.</li>
		<li>Repeat this process to make 3 flushes.</li>
	</ol>
	</li>
	<li>Gather supplies for blood gas samples, a machine for data acquisition, and lab samples.
	<ol>
		<li>Prepare two 10 mL syringes: one will be used for waste, and the other will be used to remove 10 mL of blood for labs (CBC, CMP).</li>
		<li>Prepare five 1 mL syringes for blood gas samples to be run on the arterial blood gas machine of choice.</li>
	</ol>
	</li>
	<li>Administer heparin and alteplase.
	<ol>
		<li>Use a 5 mL syringe to draw up 5 mL of heparin (5000 units) that will be used to lock the RV line at the end of exercise or cuff check to prevent clotting.</li>
		<li>Alteplase will only be needed if the RV line has clotted or the waveform is dampened.</li>
		<li>If alteplase is needed, it will need to be reconstituted with 2.2 mL of sterile water to make 2 mg of alteplase.</li>
	</ol>
	</li>
	<li>Set up the PA cuff (Figure 2) line access.
	<ol>
		<li>Acquire one 1 mL syringe and one 5 mL syringe.</li>
		<li>Using a small needle (20&#8211;22 G), fill both syringes with hypertonic saline. Use the 1 mL syringe to inflate the cuff&#160;and the 5 mL syringe to prime the line.</li>
		<li>Acquire a pressure transducer and connect the female Luer end of pressure tubing (at least 36 inches) to the male Luer end of the transducer.</li>
		<li>Make sure the bottom Luer end of the transducer is capped (Figure 2A).</li>
		<li>Connect the male end of the pressure tubing to the female Luer connection that has the white cap on a three-way stopcock.</li>
		<li>Connect a 22-G Huber needle to the male end of the three-way stopcock.</li>
		<li>Using the 5 mL syringe of hypertonic saline, access the port on the pressure transducer and open it to the Huber needle set.</li>
		<li>Flush the pressure line and Huber needle until hypertonic saline comes out of the needle.</li>
		<li>Turn the three-way stopcock toward the Huber needle to lock the stopcock to ensure no air gets into the line for access to the PA cuff (Figure 2B). Turn the three-way stopcock toward the blue cap to open access to the cuff (Figure 2C).</li>
	</ol>
	</li>
	<li>Set up RV line access.
	<ol>
		<li>Remove 2 mL of normal saline from a 1 L normal saline bag and add 2 mL of heparin (2000 units) for a total concentration of 2 units/mL.</li>
		<li>Place the normal saline bag into a pressure bag and an access bag with an IV spike.</li>
		<li>Turn the three-way stopcock on the pressure bag so the handle is perpendicular to the tubing, then inflate the bag using the hand pump until the pressure indicator turns green at approximately 250 mmHg.</li>
		<li>Turn the three-way stopcock toward the bag to maintain pressure and place the bag on the IV pole about 2 m above the ground.</li>
		<li>Connect the male end of the IV line on the pressure bag to the female end of the pressure transducer.</li>
		<li>Connect the female Luer end of the pressure tubing (at least 36 inches) to the male end of the transducer.</li>
		<li>Connect the male end of the pressure tubing to the female Luer connection on a three-way stopcock.</li>
		<li>Connect a 22 G Huber needle to the male end of the three-way stopcock.</li>
		<li>Open the heparin bag IV line and flush the entire line until heparinized saline comes out of the Huber needle. Lock the three-way stopcock connected to the Huber needle by turning it toward the Huber needle to ensure no air gets into the line for access to the RV port.</li>
	</ol>
	</li>
	<li>Transfer the sheep.
	<ol>
		<li>Transfer sheep to the exercise room via transport cage.</li>
		<li>Gently lead the sheep onto the treadmill and place a halter on the sheep.</li>
		<li>Use a halter to keep sheep at the front of the treadmill with the front legs on a small crate.</li>
	</ol>
	</li>
	<li>Access PA and RV ports.
	<ol>
		<li>Palpate ports and find the center of the port, and clean overlying skin thoroughly with alcohol wipes.</li>
		<li>Access the PA port with a Huber needle.</li>
		<li>Repeat steps 4.7.1 and 4.7.2 for RV port access.</li>
	</ol>
	</li>
	<li>Final computer set up.
	<ol>
		<li>Turn on the computer, open LabChart, and use the specifications in the supplementary methods (Supplementary File 1, Supplementary Figure 1, Supplementary Figure 2, and Supplementary Figure 3) to set up the following channels: PA Cuff, RV Pressure, RV Systolic Pressure, and Heart Rate (Figure 3A).</li>
		<li>Ensure everything is accessed correctly with the PA port closer to the head and the RV port closer to the tail (Figure 3B).</li>
		<li>Transducers should be between the computer and the sheep, with transducers at the level of the sheep&#8217;s heart (Figure 3C).</li>
		<li>Connect both pressure transducers to the interface cable and zero/calibrate the transducers as specified in the supplementary methods (Supplementary File 1, Supplementary Figure 1, Supplementary Figure 2, and Supplementary Figure 3).</li>
	</ol>
	</li>
</ol>
5. Port access
<ol>
	<li>Be sure step 4.8 is complete, and click Start on the top right of the software window to start recording the data acquisition software to capture RV and PA cuff pressure waveforms at 400 Hz.</li>
	<li>Open the PA cuff by turning the stopcock up to transduce the PA cuff pressure waveform (Figure 4A) and then turn the stopcock off toward the sheep to close the waveform (Figure 4B).
	<ol>
		<li>Keep the stopcock for PA cuff pressure off for most of the time to ensure the PA cuff does not deflate due to high pressures.</li>
	</ol>
	</li>
	<li>Place one of the heparin flushes on the three-way stopcock for the RV line and flush line with the entire flush into the RV port.</li>
	<li>Gently draw back on the syringe until the return of dark blood.
	<ol>
		<li>If it is difficult to draw back blood, power flush with another 5&#8211;10 mL of heparinized saline and then draw back with a large empty syringe such as 20 mL or 30 mL.</li>
		<li>If the clogging persists, inject 1&#8211;2 mg of alteplase into the line and wait about 10 min.</li>
	</ol>
	</li>
	<li>Open the three-way stopcock connected to the RV line to transduce RV pressure and waveform. Waveforms will vary at rest, exercise, and recovery speeds (Figure 4C).</li>
</ol>
6. Exercise regimen
<ol>
	<li>Draw blood for the baseline blood gas at initial speed 0 by turning the stopcock off towards the transducer, and use an empty 10 mL syringe to draw back 10 mL of RV blood for waste, and then 0.2&#8211;0.4 mL of RV blood with a 1 mL syringe for the blood sample.</li>
	<li>Use the 1 mL sample of RV blood for blood gas analysis and then return 10 mL of RV blood back to the sheep.</li>
	<li>Turn the stopcock to the upward position. Flush the RV line by pulling the blue&#160;tab on the RV pressure transducer to open the valve until all blood has cleared from the pressure line.</li>
	<li>Start the first exercise speed at the treadmill knob 30, which is 0.46 m/s for 10 min.</li>
	<li>Throughout the 10 min, open the PA cuff line periodically to transduce PA cuff pressures.</li>
	<li>Near the end of 10 min, obtain blood gas by performing steps 6.1&#8211;6.3.</li>
	<li>Repeat steps 6.1&#8211;6.6 for treadmill settings of 40 (0.78 m/s), 50 (1.1 m/s), 30, and 0.</li>
	<li>At the conclusion of the exercise session, use 1 mL of hypertonic saline to inflate the cuff by 150&#8211;200 mmHg.</li>
	<li>Transduce the RV pressure for a few minutes after inflation to make sure the sheep tolerates inflation.</li>
</ol>
7. Disconnecting from ports
<ol>
	<li>Remove the Huber needle from the PA cuff port quickly to prevent a pressure leak of the cuff.</li>
	<li>Inject 5 mL of heparin into the RV line, but do not flush the line so that heparin stays in the RV line and port.</li>
	<li>Remove access to the RV port quickly and clean both ports with alcohol wipes.</li>
</ol>
8. Cuff check
<ol>
	<li>Transfer the sheep to a small enclosure.</li>
	<li>Repeat steps 4.1&#8211;4.8, omitting the extra 10 mL syringe from step 4.2.1, as labs are only obtained during exercise sessions.</li>
	<li>Repeat steps 5.1&#8211;5.5 and transduce PA cuff pressure and RV waveform.</li>
	<li>Draw blood from the RV port as outlined in steps 6.1&#8211;6.3.</li>
	<li>Open the PA cuff line to ensure that the PA cuff is retaining its pressure from the previous exercise session inflation by turning the stopcock perpendicular to the pressure line.</li>
	<li>Inflate the PA cuff as needed following step 6.8 to reinflate to the cuff pressure that was obtained at that week&#8217;s exercise session.</li>
	<li>Transduce the RV pressure for a few minutes after inflation to make sure the sheep tolerates cuff inflation.</li>
	<li>Follow steps 7.1&#8211;7.3 to conclude the cuff check.</li>
</ol>
9. Complete the entire regimen 
<ol>
	<li>Repeat exercise and cuff checks weekly over the course of 8 weeks (Figure 1A,B).</li>
</ol>
10. Ending the exercise session early
<ol>
	<li>If during exercise SvO2 drops below 30% or baseline SvO2 is below 50%, immediately end the exercise session and deflate the cuff to mitigate the risk for acute irreversible decompensation of the sheep.</li>
	<li>Additionally, if the animal displays symptoms of pallor, tachypnea, grunting, teeth grinding, or mouth breathing, end the exercise session and deflate the cuff. These could be early signs of decompensation.</li>
</ol>

<ol><li>Mocumbi, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pulmonary+hypertension%5BTitle%5D)+AND+%22Nat+Rev+Dis+Primers%22%5BJournal%5D)">Pulmonary hypertension.</a> Nat Rev Dis Primers. 10 (1), 1(2024).</li>
<li>Sahni, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pulmonary+rehabilitation+and+exercise+in+pulmonary+arterial+hypertension%3A+an+underutilized+intervention%5BTitle%5D)+AND+%22J+Exerc+Rehabil%22%5BJournal%5D)">Pulmonary rehabilitation and exercise in pulmonary arterial hypertension: an underutilized intervention.</a> J Exerc Rehabil. 11 (2), 74-79 (2015).</li>
<li>Fox, B. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ambulatory+rehabilitation+improves+exercise+capacity+in+patients+with+pulmonary+hypertension%5BTitle%5D)+AND+%22J+Card+Fail%22%5BJournal%5D)">Ambulatory rehabilitation improves exercise capacity in patients with pulmonary hypertension.</a> J Card Fail. 17 (3), 196-200 (2011).</li>
<li>Zeng, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effectiveness+and+safety+of+exercise+training+and+rehabilitation+in+pulmonary+hypertension%3A+a+systematic+review+and+meta-analysis%5BTitle%5D)+AND+%22J+Thorac+Dis%22%5BJournal%5D)">Effectiveness and safety of exercise training and rehabilitation in pulmonary hypertension: a systematic review and meta-analysis.</a> J Thorac Dis. 12 (5), 2691-2705 (2020).</li>
<li>Cassady, S., Ramani, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Right+heart+failure+in+pulmonary+hypertension%5BTitle%5D)+AND+%22Cardiol+Clin%22%5BJournal%5D)">Right heart failure in pulmonary hypertension.</a> Cardiol Clin. 38 (2), 243-255 (2020).</li>
<li>Pahal, P., Sharma, S. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aPahal%2C+P+%22Idiopathic+Pulmonary+Artery+Hypertension%22">Idiopathic Pulmonary Artery Hypertension</a>. , StatPearls Publishing. Treasure Island, FL. (2023).</li>
<li>Hussain, K., Mandras, S., Desai, S. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aHussain%2C+K+%22Right+Heart+Failure%22">Right Heart Failure</a>. , StatPearls Publishing. Treasure Island, FL. (2024).</li>
<li>Ukita, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+large+animal+model+for+pulmonary+hypertension+and+right+ventricular+failure%3A+left+pulmonary+artery+ligation+and+progressive+main+pulmonary+artery+banding+in+sheep%5BTitle%5D)+AND+%22J+Vis+Exp%22%5BJournal%5D)">A large animal model for pulmonary hypertension and right ventricular failure: left pulmonary artery ligation and progressive main pulmonary artery banding in sheep.</a> J Vis Exp. (173), e62694(2021).</li>
<li>Institute for Laboratory Animal Research. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=%22Guide+for+the+Care+and+Use+of+Laboratory+Animals%22">Guide for the Care and Use of Laboratory Animals</a>. , National Academies Press. Washington, DC. (2011).</li>
<li>Musch, T. I., Larach, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((O2+content+of+blood+sampled+from+different+venous+compartments+of+the+rat%5BTitle%5D)+AND+%22J+Appl+Physiol%22%5BJournal%5D)">O2 content of blood sampled from different venous compartments of the rat.</a> J Appl Physiol. 65 (2), 988-991 (1998).</li>
<li>Ohlsson, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Monitoring+of+mixed+venous+oxygen+saturation+and+pressure+from+biosensors+in+the+right+ventricle%3A+a+24+hour+study+in+patients+with+heart+failure%5BTitle%5D)+AND+%22Eur+Heart+J%22%5BJournal%5D)">Monitoring of mixed venous oxygen saturation and pressure from biosensors in the right ventricle: a 24 hour study in patients with heart failure.</a> Eur Heart J. 16 (9), 1215-1222 (1995).</li>
<li>Johnson, C. A., et al. A Dynamic Sheep Model to Induce Pulmonary Hypertension and Right Ventricular Failure. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aJohnson%2C+CA+%22Experimental+Models+of+Cardiovascular+Diseases%3A+Methods+and+Protocols%22">Experimental Models of Cardiovascular Diseases: Methods and Protocols</a>. , Springer. New York. (2024).</li>
<li>Shanmukhappa, S. C., Lokeshwaran, S. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aShanmukhappa%2C+SC+%22Venous+Oxygen+Saturation%22">Venous Oxygen Saturation</a>. , StatPearls Publishing. Treasure Island, FL. (2024).</li>
<li>Boucherat, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+latest+in+animal+models+of+pulmonary+hypertension+and+right+ventricular+failure%5BTitle%5D)+AND+%22Circ+Res%22%5BJournal%5D)">The latest in animal models of pulmonary hypertension and right ventricular failure.</a> Circ Res. 130 (9), 1466-1486 (2022).</li>
<li>Long, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Skeletal+muscle+blood+flow+during+exercise+is+reduced+in+a+rat+model+of+pulmonary+hypertension%5BTitle%5D)+AND+%22Am+J+Physiol%22%5BJournal%5D)">Skeletal muscle blood flow during exercise is reduced in a rat model of pulmonary hypertension.</a> Am J Physiol. 323 (4), R561-R570 (2022).</li>
<li>Rothman, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Challenges+in+the+development+of+chronic+pulmonary+hypertension+models+in+large+animals%5BTitle%5D)+AND+%22Pulm+Circ%22%5BJournal%5D)">Challenges in the development of chronic pulmonary hypertension models in large animals.</a> Pulm Circ. 7 (1), 156-166 (2017).</li>
<li>Stam, K., Clauss, S., Taverne, Y., Merkus, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chronic+thromboembolic+pulmonary+hypertension%3A+what+have+we+learned+from+large+animal+models%5BTitle%5D)+AND+%22Front+Cardiovasc+Med%22%5BJournal%5D)">Chronic thromboembolic pulmonary hypertension: what have we learned from large animal models.</a> Front Cardiovasc Med. 8, 574360(2021).</li>
<li>Stam, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Exercise+facilitates+early+recognition+of+cardiac+and+vascular+remodeling+in+chronic+thromboembolic+pulmonary+hypertension+in+swine%5BTitle%5D)+AND+%22Am+J+Physiol%22%5BJournal%5D)">Exercise facilitates early recognition of cardiac and vascular remodeling in chronic thromboembolic pulmonary hypertension in swine.</a> Am J Physiol. 314 (3), H627-H642 (2017).</li>
<li>Stam, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Exercise+response+in+a+new+porcine+model+of+chronic+embolic+pulmonary+hypertension%5BTitle%5D)+AND+%22FASEB+J%22%5BJournal%5D)">Exercise response in a new porcine model of chronic embolic pulmonary hypertension.</a> FASEB J. 29 (S1), LB597(2015).</li>
<li>Morris, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Exercise-based+rehabilitation+programmes+for+pulmonary+hypertension%5BTitle%5D)+AND+%22Cochrane+Database+Syst+Rev%22%5BJournal%5D)">Exercise-based rehabilitation programmes for pulmonary hypertension.</a> Cochrane Database Syst Rev. 3 (3), CD011285(2023).</li>
<li>Rusakova, Y., Zhuravleva, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Functional+anatomy+of+the+sheep+heart+as+a+model+for+testing+cardiovascular+devices%5BTitle%5D)+AND+%22Sovrem+Tekhnol+Med%22%5BJournal%5D)">Functional anatomy of the sheep heart as a model for testing cardiovascular devices.</a> Sovrem Tekhnol Med. 17 (2), 13-22 (2025).</li>
<li>Divincenti, L., Westcott, R., Lee, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sheep+%28Ovis+aries%29+as+a+model+for+cardiovascular+surgery+and+management+before%2C+during+and+after+cardiopulmonary+bypass%5BTitle%5D)+AND+%22J+Am+Assoc+Lab+Anim+Sci%22%5BJournal%5D)">Sheep (Ovis aries) as a model for cardiovascular surgery and management before, during and after cardiopulmonary bypass.</a> J Am Assoc Lab Anim Sci. 53 (5), 439-448 (2014).</li>
<li>Ukita, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ambulatory+seven-day+mechanical+circulatory+support+in+sheep+model+of+pulmonary+hypertension+and+right+heart+failure%5BTitle%5D)+AND+%22J+Heart+Lung+Transplant%22%5BJournal%5D)">Ambulatory seven-day mechanical circulatory support in sheep model of pulmonary hypertension and right heart failure.</a> J Heart Lung Transplant. 43 (2), 293-302 (2025).</li>
<li>Heerdt, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Right+ventricular+pressure+waveform+analysis%3A+clinical+relevance+and+future+directions%5BTitle%5D)+AND+%22J+Cardiothorac+Vasc+Anesth%22%5BJournal%5D)">Right ventricular pressure waveform analysis: clinical relevance and future directions.</a> J Cardiothorac Vasc Anesth. 38 (10), 2433-2445 (2024).</li>
<li>Heerdt, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Integrating+right+ventricular+pressure+waveform+analysis+with+two-point+volume+measurement+for+quantification+of+systolic+and+diastolic+function%3A+experimental+validation+and+clinical+application%5BTitle%5D)+AND+%22J+Cardiothorac+Vasc+Anesth%22%5BJournal%5D)">Integrating right ventricular pressure waveform analysis with two-point volume measurement for quantification of systolic and diastolic function: experimental validation and clinical application.</a> J Cardiothorac Vasc Anesth. 37 (10), 1929-1937 (2023).</li>
</ol>

The authors have no conflicts of interest to disclose.

The presented sheep PH-RVF model has been updated from the previous version by combining it with a treadmill exercise platform to study the interaction between exercise and disease development8. Because each animal may respond differently to cuff inflation, for consistent exercise conditioning across animals, treadmill speeds during an exercise session were adjusted to include working speeds and recovery speeds. Increasing treadmill speed gradually with three progressive working speeds and then tw...

Pulmonary hypertension (PH) is a complex disease that causes a wide array of symptoms. Symptoms can be mild, such as dyspnea and exercise intolerance, to severe, such as respiratory decline and overt right ventricle failure (RVF)1. As the right heart afterload increases, the right ventricle (RV) begins to dilate, causing systolic dysfunction and reduced ejection fraction. This mismatch in cardiac demand and output makes activities of daily living and exercise intolerable, leading to both physical and mental decline. Previously, exercise in the setting of pulmonary hypertension was thought to be detrimental2. Recently, many studies have demonstrated that a pulmonary rehabilitation program with exercise could reduce dyspnea and improve overall quality of life both physically and mentally2,3,4. However, the study of exercise in patients with PH has been limited to those with stable disease due to potential cardiopulmonary decompensation.
Rapid decompensation is a feared complication of PH-RVF. Some people with PH may have a period of adequate compensation and only have mild symptoms, with decompensation slowly happening over a period of months to years. Others, unfortunately, may have more severe PH and can decompensate rapidly with any type of exertion. Exercise can exacerbate the disease and cause rapid cardiopulmonary collapse due to a cycle of increased RV metabolic demand, decreased ejection fraction, and ongoing RV ischemia. This is a very serious complication because patients who develop decompensated RVF&#160;require hospital admission and have mortality rates as high as 40%5. PH can affect people of any age with most cases developing from left heart disease (Group 2) and lung disease (Group 3). In rare instances, PH can develop from idiopathic causes and is more common in females in their fourth decade of life (Group 1)6. While disease progression can be tempered with medical management, there is no definitive pharmacological cure. Once patients reach end-stage RVF, the only definitive treatment is lung or heart-lung transplantation7.
Due to the morbidity and mortality of PH and subsequent RVF, we previously created a clinically relevant PH-RVF model in sheep to develop novel therapies8. In this model, we ligated the left pulmonary artery (LPA) and placed an inflatable cuff that served as a vascular occluder around the main pulmonary artery (MPA). Over the course of 8 weeks, we increased the pressure inside this cuff to decrease flow through the main pulmonary artery to increase RV afterload and induce RV remodeling. This model has now been further developed by incorporating an exercise regimen to better study the interaction between PH and exercise. This protocol is unique because it captures changes in hemodynamic parameters such as right ventricular systolic pressure (RVSP) and heart rate (HR) in real time. RV blood was used as a surrogate for mixed venous blood to analyze changes in SvO2 to compare oxygen extraction at varying exercise speeds. The exercise regimen and data acquisition methods are outlined below as a resource for investigators to further develop a better understanding of the complex pathophysiology of PH-RVF.

<table><tbody><tr><td>0.9% Normal Saline, 1000 mL</td><td>Baxter Healthcare Corp</td><td>0338-0049-04</td><td>Medication, Chronic PH</td></tr><tr><td>16 mm Heavy Duty Occluder with actuating tubing</td><td>Access Technologies</td><td>OC-16HD</td><td>Disposable, Chronic PH</td></tr><tr><td>70% isopropyl alcohol prep pads</td><td>Medline</td><td>MDS090670</td><td>Disposable, Chronic PH</td></tr><tr><td>Aluminum Lamb and Goat Treadmill</td><td>Livestock Performance Products</td><td>&amp;nbsp;DC314</td><td>Equipment</td></tr><tr><td>Bags, Infusion: Nonsterile Novaplus Infusion Bag, 500 mL</td><td>Medline</td><td>TCV4005H</td><td>Disposable, Chronic PH</td></tr><tr><td>Blue Clave</td><td>Medline</td><td>BOPC1000</td><td>Disposable, Chronic PH</td></tr><tr><td>Cathflo Activase (alteplase) 2 mg</td><td>Cathflo</td><td>NDC 50242004164</td><td>Medication, Chronic PH</td></tr><tr><td>Computer</td><td>&amp;nbsp;Dell</td><td>&amp;nbsp;Lattitude 7400</td><td>Equipment</td></tr><tr><td>Data acquisition hardware</td><td>ADInstruments</td><td>PowerLab 16/30</td><td>Equipment</td></tr><tr><td>EPOC Point-of-care blood gas analyzer</td><td>Siemens Healthineers</td><td>Siemens-Epoc-R</td><td>Equipment</td></tr><tr><td>Flow Meter</td><td>Transonic</td><td>https://www.transonic.com/tubing-flow-meters-manufacturers</td><td></td></tr><tr><td>Gauze Sponges: Sterile X-ray Compatible Gauze Sponges, 16-Ply, 4&amp;rdquo; &amp;times; 4&amp;rdquo;</td><td>Medline</td><td>PRM21430LFH</td><td>Disposable, Chronic PH</td></tr><tr><td>GEM 7000 with iQM3</td><td>Werfen</td><td>6000228442</td><td>Equipment</td></tr><tr><td>Heparin</td><td>Fresenius Kabi</td><td>63323-540-31</td><td>Medication, Chronic PH</td></tr><tr><td>Hospira Primary IV Sets, 80&amp;rdquo;</td><td>Patterson Veterinary</td><td>07-835-0123</td><td>Disposable, Chronic PH</td></tr><tr><td>Hypertonic saline 3%</td><td>Baxter Healthcare Corp.</td><td>0338-0054-03</td><td>Medication, Chronic PH</td></tr><tr><td>Hypodermic Needle with Bevel and Regular Wall, 20 G &amp;times; 1&amp;rdquo;</td><td>Medline</td><td>B-D305175Z</td><td>Disposable, Chronic PH</td></tr><tr><td>Interface Cable, Edwards LifeScience Transducer to ADInstruments Bridge Amplifier</td><td>Fogg System</td><td>0395-2434</td><td>Equipment</td></tr><tr><td>Labchart software</td><td>ADInstruments</td><td>Labchart 8</td><td>Equipment</td></tr><tr><td>Needles: Hypodermic Needle with Regular Bevel, Sterile, 18 G &amp;times; 1.5&amp;rdquo;</td><td>Medline</td><td>B-D305185Z</td><td>Disposable, Chronic PH</td></tr><tr><td>Octal Bridge Amplifier</td><td>ADInstruments</td><td>FE228</td><td>Equipment</td></tr><tr><td>Port-A-Cath Huber Needle, Straight, 22 G &amp;times; 1-1/2&amp;rdquo;</td><td>Medline</td><td>AAKM21200724</td><td>Disposable, Chronic PH</td></tr><tr><td>Sheep Halter</td><td>Weaver Livestock</td><td>&amp;nbsp;35-7840-S20</td><td>Equipment</td></tr><tr><td>Sterile Leur-Lock Syringe, 1 mL</td><td>Fisher Scientific</td><td>BD309628</td><td>Disposable, Chronic PH</td></tr><tr><td>Sterile Luer-Lock Syringe, 10 mL</td><td>Medline</td><td>SYR110010Z</td><td>Disposable, Chronic PH</td></tr><tr><td>Sterile Luer-Lock Syringe, 3 mL</td><td>Medline</td><td>SYR103010Z</td><td>Disposable, Chronic PH</td></tr><tr><td>Sterile Luer-Lock Syringe, 5 mL</td><td>Medline</td><td>SYR105010Z</td><td>Disposable, Chronic PH</td></tr><tr><td>Sterile Water</td><td>Fresenius Kabi</td><td>918550</td><td>Medication</td></tr><tr><td>Stopcock: 3-Way Stopcock with Handle in OFF Position, Rotating Adaptor Male Collar Fitting, 45 PSI</td><td>Medline</td><td>DYNJSC301</td><td>Disposable, Chronic PH</td></tr><tr><td>Transducer clip</td><td>Edwards LifeScience</td><td>TCLIP05</td><td>Equipment</td></tr><tr><td>Transonic Perivascular Flow Probe (PAU Series)</td><td>ADInstruments</td><td>https://www.adinstruments.com/products/perivascular-flowprobes</td><td></td></tr><tr><td>Transport Cage/ Large Animal Caging</td><td>Ancare</td><td>&amp;nbsp;ANAT305660SS</td><td>Equipment</td></tr><tr><td>Trigger Aneroid Gauge (Sphygmomanometer)</td><td>Patterson Veterinary</td><td>07-815-0464</td><td>Equipment</td></tr><tr><td>TruWave Disposable Pressure Transducer Kits by Edwards Lifesciences</td><td>Medline</td><td>VSYPX260</td><td>Disposable, Chronic PH</td></tr><tr><td>Tubing: Pressure Monitoring Tubing with Fixed Male Luer Lock and Female Fitting, Low Pressure, 72&amp;rdquo; L</td><td>Medline</td><td>DYNJPMTBG72MF</td><td>Disposable, Chronic PH</td></tr><tr><td>Umbilical Tape, Cotton, 3-Strand, 1/8 x 36&quot;</td><td>Medline</td><td>DYNJPMTBG72MF</td><td>Disposable, Chronic PH</td></tr></tbody></table>

structured exercise regimen in pulmonary hypertension-right ventricular failure in an ovine model

Structured Exercise Regimen in Pulmonary Hypertension-Right Ventricular Failure in an Ovine Model

Right heart failure (RHF) is a significant cause of morbidity and mortality from pulmonary hypertension (PH). To better understand the pathophysiology and implications of exercise-induced stress, we implemented an exercise regimen to further characterize this disease using our previously developed ovine model of chronic pulmonary hypertension-right ventricular failure (PH-RVF). To this end, eight Dorset cross sheep underwent the PH-RVF model via ligation of the left pulmonary artery (LPA) and progressive occlusion of the main pulmonary artery (MPA) with an inflatable cuff. The cuff and right ventricle (RV) pressure lines were subcutaneously tunneled to a port for access. Over eight weeks, each sheep underwent a weekly exercise regimen and cuff check (CC). The exercise regimen consisted of working speeds and recovery speeds for 10 min each. During exercise, we accessed both ports to transduce cuff pressure, hemodynamics, and take RV blood gases. At exercise conclusion, the PA cuff was inflated by 150-200 mmHg to increase RV afterload. A CC and RV blood gas were performed a few days after inflation to confirm cuff pressure and ensure compensation. Over the course of eight weeks, the SvO2 remained relatively stable at maximum intensity at week 1 vs week 8: 62.7 &#177; 4.5% vs 69.8 &#177; 4.0% despite the RVSP increasing from week 1 to week 8: 78 &#177; 8 mmHg vs 96 &#177; 8 mmHg. Additionally, the distance traveled increased from week 1 to week 8: 1390 &#177; 297 m vs 1834 &#177; 189 m, despite the PA cuff pressure at week 8 being increased to 777 &#177; 98 mmHg. This suggests that despite increased RV afterload, exercise may aid in an adaptive response and compensation to exercise in the setting of PH-RVF. This exercise regimen provides novel information about the effects of exercise in PH-RVF and enables complex studies of exercise physiology in a large animal model of PH-RVF.

All data are represented as mean±SEM. Over the course of eight weeks, the SvO2 remained relatively stable at maximum treadmill speed at week 1 vs week 8: 62.7 ± 4.5% vs 69.8 ± 4.0% (Figure 5A), despite the RVSP increasing from week 1 to week 8: 78 ± 8 mmHg vs 96 ± 8 mmHg (Figure 5B). The distance traveled during exercise increased from week 1 to week 8: 1390 ± 297 m vs 1834 ± 189 m (Figure 5C), despite the PA c...

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.

Right heart failure (RHF) is a significant cause of morbidity and mortality from pulmonary hypertension (PH). To better understand the pathophysiology and ...

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.

structured-exercise-regimen-pulmonary-hypertension-right-ventricular

Research

JoVE Journal

Medicine

Chronic Thromboembolic Pulmonary Hypertension (CTEPH) and Right Ventricular (RV) dysfunction were induced in piglets by progressive obstruction of the pulmonary arteries. Consequences were remarkably similar to those observed in CTEPH patients. This animal model would be a very useful tool for pathophysiology and therapeutic experiments on CTEPH and RV failure.

Chronic Thromboembolic Pulmonary Hypertension and Assessment of Right Ventricular Function in the Piglet

Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine

We present a protocol of creating right ventricular dysfunction in a pig model by inducing ARDS. We demonstrate invasive monitoring of left and right ventricular cardiac output using flow probes around the aorta and the pulmonary artery, as well as blood pressure measurements in the aorta and pulmonary artery.

Invasive Hemodynamic Monitoring of Aortic and Pulmonary Artery Hemodynamics in a Large Animal Model of ARDS

We present a protocol to induce and phenotype an acute right heart failure in a large animal model with chronic pulmonary hypertension. This model can be used to test therapeutic interventions, to develop right heart metrics or to improve the understanding of acute right heart failure pathophysiology.

Induction and Phenotyping of Acute Right Heart Failure in a Large Animal Model of Chronic Thromboembolic Pulmonary Hypertension

Here, we provide a useful approach for studying the mechanism of right ventricular failure. A more convenient and efficient approach to pulmonary artery constriction is established using surgical instruments made inhouse. In addition, methods to evaluate the quality of this approach by echocardiography and catheterization are provided.

Induction of Right Ventricular Failure by Pulmonary Artery Constriction and Evaluation of Right Ventricular Function in Mice

Here we present a closed chest approach to admittance-based bi-ventricular pressure-volume loop recordings in pigs with acute right ventricular dysfunction.

Closed Chest Biventricular Pressure-Volume Loop Recordings with Admittance Catheters in a Porcine Model

This manuscript describes the surgical technique and experimental approach to develop severe right ventricular pressure overload to model their adaptive and maladaptive phenotypes.

A Large Animal Model for Pulmonary Hypertension and Right Ventricular Failure: Left Pulmonary Artery Ligation and Progressive Main Pulmonary Artery Banding in Sheep

The present protocol describes the echocardiographic characterization of right ventricular morphology and function in a rat model of pulmonary arterial hypertension.

Comprehensive Echocardiographic Assessment of Right Ventricle Function in a Rat Model of Pulmonary Arterial Hypertension

Right ventricular failure and functional tricuspid regurgitation are associated with left-sided heart disease and pulmonary hypertension, which contribute significantly to morbidity and mortality in patients. Establishing a chronic ovine model to study right ventricular failure and functional tricuspid regurgitation will help in understanding their mechanisms, progression, and possible treatments.

Chronic Ovine Model of Right Ventricular Failure and Functional Tricuspid Regurgitation

We describe a murine model of right ventricular pressure overload-induced by pulmonary trunk banding. Detailed protocols for intubation, surgery, and phenotyping by echocardiography are included in the paper. Custom-made instruments are used for intubation and surgery, allowing for fast and inexpensive reproduction of the model.

A Murine Model of Pressure Overload-Induced Right Ventricular Hypertrophy and Failure by Pulmonary Trunk Banding

The presentation of detailed methods for the evaluation of right ventricle function will enhance the quality and reliability of pulmonary hypertension research, offering a robust framework for future studies and enhancing reproducibility across different laboratories.

Evaluation of Right Ventricular Function in Experimental Models of Pulmonary Arterial Hypertension

Learn structured exercise assessment in pulmonary hypertension-right ventricular failure using an ovine model. This method enables controlled hemodynamic monitoring during progressive disease to study adaptive physiological responses.

Structured Exercise Regimen in Pulmonary Hypertension-Right Ventricular Failure in an Ovine Model

Explore More Videos