The authors have no acknowledgements.

This prospective experimental trial with 21 anesthetized male and female domestic pigs (German landrace) at the age of 3&#8211;6 months with a body weight between 45-55 kg was approved by the Governmental Commission on the Care and Use of Animals of the City of Hamburg (Reference-No. 18/17). According to the ARRIVE guidelines, all experiments were carried out and all animals received care in compliance with the &#39;Guide for the Care and Use of Laboratory Animals&#39; (NIH publication No. 86-23, revised 1996)11.
1. Flow Probe Two-point Calibration
<ol>
	<li>Put flow probes in deionized water and connect the probe to the transonic flow probe system by putting the plug into the perivascular flow module.</li>
	<li>Open the data analysis software (e.g., LabChart 8).</li>
	<li>For a two-point calibration, start a measurement by setting the flow probe system to Zero and after a few seconds to Scale.</li>
	<li>In the data analysis software window, go to Units Conversion and choose two-point calibration. Mark a baseline to set to zero. Then, mark an area with 10 L/min and set to 1 V as a preset value.</li>
	<li>Repeat the procedure for the other probe.</li>
</ol>
2. Millar Catheter Calibration
<ol>
	<li>Prior to the zeroing and calibration, pre-soak the tip of the catheter in sterile body temperature warm water for 30 min.</li>
	<li>Connect the Millar catheter to the bridge amplifier by putting the plug into the bridge amplifier module.</li>
	<li>Start the data analysis software.</li>
	<li>Put the tip of the catheter into the pneumatic zeroing tool, set the value to 0 mmHg and start a measurement by clicking Start in the program.</li>
	<li>Keep the measurement running and set the pneumatic zeroing tool to 100 mmHg. Stop the measurement by clicking Stop.</li>
	<li>Run the data analysis software by pressing Start and then press Stop. Click Amplify in the window of bridge and choose Units. Set the baseline of 0 and 100 mmHg, accordingly. According to the preset value for calibration that the software provides, the catheter is now calibrated for all body pressures.</li>
	<li>Repeat the procedure for the other Millar catheter.</li>
</ol>
3. Preparation of the Pig
<ol>
	<li>Medicate the pig by injecting 20 mg/kg of Ketanest, 4 mg/kg of Azaperon and 0.1 mg/kg Midazolam intramuscularly and place a 20 G IV-line into a vein of the ear.</li>
	<li>Place ECG stickers on the chest and oxygen probe on the tail.</li>
	<li>Administer pure oxygen (15&#8211;18 L/min) via the pig&#39;s nose using a mask and surgically prepare down to the trachea.</li>
	<li>Put a loop around the trachea, use a scalpel (11 blade) to make an incision into the trachea and place an 8.5 Mallinckrodt tube into it for a safe airway. Fix the tube with the preset loop and close the skin with sutures.</li>
	<li>Begin anesthesia with Sevoflurane using a MAC of 0.9 (in adolescent pigs equivalent to an endexpiratory concentration of 2.0%)&#160;&#160;and infusion of 0.01 mg/(kg&#8729;h) Fentanyl. Start mechanical ventilation with a tidal volume of 10 mL/kg, a rate of 14/min, and a positive end expiratory pressure (PEEP) of 7 mmHg. Set the inspiratory oxygen rate (fiO2) to 0.3. After 10 min depth of anesthesia is deep enough to perform surgery safely. No elevation of HR and BP should be detected.</li>
	<li>Maintain fluid balance at basal volume rate of 10 mL/(kg&#8729;h) cristalloid using an infusion pump.</li>
	<li>Gently clean the pig&#39;s skin using soap water. Use a skin disinfection solution containing povidone-iodine to decrease skin contamination.</li>
</ol>
4. Vital Parameter Measurements
<ol>
	<li>Use an ultrasound for inserting a 5 F thermistor tipped arterial catheter into the right femoral artery, an 8 F introducer sheath into the left femoral artery, a central venous catheter and an 8 F introducer sheath into the jugular vein (Figure 1).</li>
	<li>Place the catheter placement using Seldinger&#39;s technique12.
	<ol>
		<li>Place a needle into the target vessel under ultrasound vision.</li>
		<li>Put a wire through the needle into the vessel, verify the correct placement of the wire using ultrasound and keep the wire in the vessel throughout the whole procedure. Remove the needle and place a dilator onto the wire.</li>
		<li>With gentle pressure, put the dilator through the skin into the vessel using the wire as guidance. Remove the dilator, put the catheter onto the wire, make sure to the end of the wire is seen at the end of the catheter and place the catheter it into the vessel.</li>
		<li>Remove the wire by gently pulling it out of the catheter.</li>
	</ol>
	</li>
	<li>Insert a 7F pulmonary artery catheter (PAC) into the 8F introducer sheath and place it in the RV. If needed for taking mixed venous blood gas samples, insert the PAC further into the PA until a pulmonary artery curve is shown on to the monitor and pull it back after receiving the samples.</li>
	<li>Insert the first Millar-tip catheter into the 8F introducer sheath in the left femoral artery and placing it in the aorta.</li>
	<li>Perform a mini-laparotomy (approximately 5&#8211;10 cm is enough) above the symphysis by using the electrocautery for prepping down to the linea alba.
	<ol>
		<li>Open the linea alba with scissors and pull out the bladder very gently.</li>
		<li>Put a purse string suture in the bladder using a 3/0 suture and make an incision into the bladder with a scalpel (11 blade).</li>
		<li>Insert a urinary catheter into the bladder, inflate the catheter&#39;s balloon with water and fix it using the purse-string suture. Close the abdomen with a 3/0 suture.</li>
	</ol>
	</li>
</ol>
5. Surgical Preparation of the Heart
<ol>
	<li>Before opening the chest increasing the fiO2 to 1.0 and administer 0.1 mg kg(-1) pancuronium initial bolus intravenously13.</li>
	<li>Perform a median sternotomy.
	<ol>
		<li>Use the electrocautery for prepping down to the sternum. Gently dissect the sternum from the surrounding tissue before dividing the bone with an oscillating saw.</li>
		<li>Use the electrocautery to reduce bleeding and seal the sternum with bone wax. Place a sternal rib spreader between the two halves of the opened sternum and widely open the chest as much as needed for surgery by twisting the handle on the device.</li>
	</ol>
	</li>
	<li>Open the pericardium gently using scissors and forceps and fix it to the skin with a 2/0 suture.</li>
	<li>Dissect down the pulmonary and the artery ascending aorta very gently to avoid bleeding. Carefully place the ultrasound flow probes around both arteries, respectively (Figure 2).</li>
	<li>Place 2 purse string sutures in the pulmonary artery using a 5/0 suture. Use a scalpel (11 blade) to make a small stitch incision (approximately 1 mm) in the middle of the purse strings and place the Millar catheter into the pulmonary artery before fixing it (Figure 3).</li>
	<li>Carefully clamp the LAA and place 2 purse string sutures in it using a 4/0 suture. Make a small incision and place a central venous line into the left atrium before fixing it using the purse string sutures (Figure 3).</li>
	<li>Close the pericardium by suturing a sterile glove onto it, to maintain hemodynamics reliable (Figure 4). Perform the sternal closure with wires and close the skin with a 3/0 suture.</li>
</ol>
6. Assessment and Data Acquisition
<ol>
	<li>Start each measurement with 2 min of AO and PA flow measurements, as well as AO and PA pressure measurements using the data analysis software by clicking Start and Stop button in the program.</li>
	<li>Perform transcardiopulmonary thermodilution to provide cardiac output (CO) as well as pulse pressure variance (PPV) and stroke volume variance (SVV) by using the PiCCO2 system. To start the measurement, click the TD | Start.</li>
	<li>Consecutive inject 15 mL of 10 &#176;C cold saline into a thermistor at the central venous line in the jugular vein three times for thermodilution at each measurement step.</li>
	<li>Take an arterial, central venous and mixed venous blood gas sample after each transcardiopulmonary thermodilution measurement step.</li>
</ol>
7. Volume Optimizing
<ol>
	<li>After a baseline measurement M0 (steps 6.1&#8211;6.4) of all parameters, administer a volume loading step using 5 mL/kg of colloidal infusion (Voluven) using an infusion pump that is connected to the central venous line.</li>
	<li>After 5 min of equilibration, start another measurement step M1 (steps 6.1&#8211;6.4). If the newly generated cardiac output measured by thermodilution using the PICCO2 system (see step 6.2&#8211;6.3) does not increase compared to the formerly measured CO by at least 10%, start another volume loading step (step 7.1).</li>
	<li>Continue with volume loading and equilibration steps until there is no more increase in CO of more than 10%. Now, a balanced fluid status is reached.</li>
</ol>
8. Induction of ARDS with Right Ventricular Dysfunction
<ol>
	<li>Increase the fiO2 to at least 0.5 to 0.8 as required to maintain a spO2 of at least 90%.</li>
	<li>Induce an ARDS with consecutive right ventricular dysfunction by infusion of oleic acid (OA) (0.03&#8211;0.06 mL/kg for about 2 h).</li>
	<li>Use continuous administration of adrenalin using a perfusor (3 mg of adrenalin in 50 mL of saline) to keep hemodynamics stable. Increase the infusion rate as required to maintain a mean arterial pressure of 50 mmHg.</li>
	<li>Add calcium, magnesium and antiarrhythmics (1% Lidocain) as required during the infusion of OA to maintain a stable sinus rhythm.</li>
</ol>
9. Volume Optimizing
<ol>
	<li>After induction of mild to moderate ARDS, perform another measurement of all parameters (M2) by completing steps 6.1&#8211;6.4. 
	NOTE: Now, the baseline model for hemodynamic measurements in ARDS in a pig model is set. For further investigation on volume responsiveness in ARDS and right ventricular dysfunction start to reduce volume load by taking as much blood as need per protocol or increasing volume load by adding a defined amount of infusion.</li>
</ol>
10. Finalization
<ol>
	<li>After finishing the measurements euthanize the pigs while under anesthesia by injecting 1mmol/kg potassium chloride intravenously.</li>
</ol>

<ol>
	<li>Kapur, N. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+Circulatory+Support+Devices+for+Acute+Right+Ventricular+Failure.">Mechanical Circulatory Support Devices for Acute Right Ventricular Failure.</a> Circulation. 136, 314-326 (2017).</li><li>Zochios, V., Jones, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+right+heart+syndrome+in+the+critically+ill+patient.">Acute right heart syndrome in the critically ill patient.</a> Heart Lung Vessel. 6 (3), 157-170 (2014).</li><li>Ranucci, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluid+responsiveness+and+right+ventricular+function+in+cardiac+surgical+patients.+A+multicenter+study.">Fluid responsiveness and right ventricular function in cardiac surgical patients. A multicenter study.</a> HSR Proceedings in Intensive Care and Cardiovascular Anesthesia. 1 (1), 21-29 (2009).</li><li>Mehta, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impact+of+right+ventricular+involvement+on+mortality+and+morbidity+in+patients+with+inferior+myocardial+infarction.">Impact of right ventricular involvement on mortality and morbidity in patients with inferior myocardial infarction.</a> Journal of the American College of Cardiology. 37, 37-43 (2001).</li><li>Vieillard-Baron, A., Charron, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preload+responsiveness+or+right+ventricular+dysfunction.">Preload responsiveness or right ventricular dysfunction.</a> Critical Care Medicine. 37 (9), 2662-2663 (2009).</li><li>Marik, P. E., Baram, M., Vahid, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+central+venous+pressure+predict+fluid+responsiveness?+A+systematic+review+of+the+literature+and+the+tale+of+seven+mares.">Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares.</a> Chest. 134 (1), 172-178 (2008).</li><li>Marik, P. E., Cavallazzi, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+the+central+venous+pressure+predict+fluid+responsiveness?+An+updated+meta-analysis+and+a+plea+for+some+common+sense.">Does the central venous pressure predict fluid responsiveness? An updated meta-analysis and a plea for some common sense.</a> Critical CareMedicine. 41 (7), 1774-1781 (2013).</li><li>Eskesen, T. G., Wetterslev, M., Perner, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systematic+review+including+re-analyses+of+1148+individual+data+sets+of+central+venous+pressure+as+a+predictor+of+fluid+responsiveness.">Systematic review including re-analyses of 1148 individual data sets of central venous pressure as a predictor of fluid responsiveness.</a> Intensive Care Medicine. 42 (3), 324-332 (2016).</li><li>Kilkenny, C., Browne, W. J., Cuthill, I. C., Emerson, M., Altman, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+bioscience+research+reporting:+the+ARRIVE+guidelines+for+reporting+animal+research.">Improving bioscience research reporting: the ARRIVE guidelines for reporting animal research.</a> Osteoarthritis and cartilage, Osteoarthritis Research Society. 20 (2), 56-60 (2012).</li><li>Akella, A., Sharma, P., Pandey, R., Deshpande, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+oleic+acid-induced+acute+respiratory+distress+syndrome+model+in+rat.">Characterization of oleic acid-induced acute respiratory distress syndrome model in rat.</a> Indian Journal of Experimental Biology. 52 (7), 712-719 (2014).</li><li>Meinhardt, J. P., Friess, U., Bender, H. J., Hirschl, R. B., Quintel, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+among+cardiac+index,+inspiration/expiration+ratio,+and+perfluorocarbon+dose+during+partial+liquid+ventilation+in+an+oleic+acid+model+of+acute+lung+injury+in+sheep.">Relationship among cardiac index, inspiration/expiration ratio, and perfluorocarbon dose during partial liquid ventilation in an oleic acid model of acute lung injury in sheep.</a> Journal of Pediatric Surgery. 40 (9), 1395-1403 (2005).</li><li>Zhu, Y. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atrial+natriuretic+peptide+attenuates+inflammatory+responses+on+oleic+acid-induced+acute+lung+injury+model+in+rats.">Atrial natriuretic peptide attenuates inflammatory responses on oleic acid-induced acute lung injury model in rats.</a> Chinese Medical Journal (English. 126 (4), 747-750 (2013).</li><li>Gould, D. A., Baun, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Role+of+the+Pulmonary+Afferent+Receptors+in+Producing+Hemodynamic+Changes+during+Hyperinflation+and+Endotracheal+Suctioning+in+an+Oleic+Acid-Injured+Animal+Model+of+Acute+Respiratory+Failure.">The Role of the Pulmonary Afferent Receptors in Producing Hemodynamic Changes during Hyperinflation and Endotracheal Suctioning in an Oleic Acid-Injured Animal Model of Acute Respiratory Failure.</a> Biology Research for Nursing. 1 (3), 179-189 (2000).</li><li>Galie, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2015+ESC/ERS+Guidelines+for+the+diagnosis+and+treatment+of+pulmonary+hypertension.">2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension.</a> European Heart Journal. 37, 67-119 (2015).</li><li>Galie, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2015+ESC/ERS+Guidelines+for+the+diagnosis+and+treatment+of+pulmonary+hypertension:+The+Joint+Task+Force+for+the+Diagnosis+and+Treatment+of+Pulmonary+Hypertension+of+the+European+Society+of+Cardiology+(ESC)+and+the+European+Respiratory+Society+(ERS),+Endorsed+by:+Association+for+European+Paediatric+and+Congenital+Cardiology+(AEPC),+International+Society+for+Heart+and+Lung+Transplantation+(ISHLT).">2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension: The Joint Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS), Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC), International Society for Heart and Lung Transplantation (ISHLT).</a> European Respiratory Journal. 46, 903-975 (2015).</li><li>Oliveira, R. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Usefulness+of+pulmonary+capillary+wedge+pressure+as+a+correlate+of+left+ventricular+filling+pressures+in+pulmonary+arterial+hypertension.">Usefulness of pulmonary capillary wedge pressure as a correlate of left ventricular filling pressures in pulmonary arterial hypertension.</a> Journal of Heart and Lung Transplantation. 33 (4), 459 (2014).</li><li>Hoeper, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+global+view+of+pulmonary+hypertension.">A global view of pulmonary hypertension.</a> Lancet Respiratory Medicine. 4, 306-322 (2016).</li><li>Nagy, A. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+pulmonary+capillary+wedge+pressure+accurately+reflects+both+normal+and+elevated+left+atrial+pressure.">The pulmonary capillary wedge pressure accurately reflects both normal and elevated left atrial pressure.</a> American Heart Journal. 167 (6), 876-883 (2014).</li><li>Daughters, G. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+the+pericardium+on+left+ventricular+diastolic+filling+and+systolic+performance+early+after+cardiac+operations.">Effects of the pericardium on left ventricular diastolic filling and systolic performance early after cardiac operations.</a> Journal of Thoracic and Cardiovascular Surgery. 104 (4), 1084-1091 (1992).</li><li>Zimmerman, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Posttransfusion+Increase+of+Hematocrit+per+se+Does+Not+Improve+Circulatory+Oxygen+Delivery+due+to+Increased+Blood+Viscosity.">Posttransfusion Increase of Hematocrit per se Does Not Improve Circulatory Oxygen Delivery due to Increased Blood Viscosity.</a> Anesthesia &amp; Analgesia. 124 (5), 1547-1554 (2017).</li><li>Giglioli, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hemodynamic+effects+in+patients+with+atrial+fibrillation+submitted+to+electrical+cardioversion.">Hemodynamic effects in patients with atrial fibrillation submitted to electrical cardioversion.</a> International Journal of Cardiology. 168 (4), 4447-4450 (2013).</li></ol>

Daniel A. Reuter is a member of Pulsion Medical Advisory Board. Constantin J.C. Trepte has received honorary award for lectures by Maquet. All other authors declare no conflicts of interest.

ARDS, complicated by pulmonary hypertension, is a very deadly disease. For patients suffering from this condition, further information about treating it is necessary. When working and researching with living creatures, it is very important to be as sensible as possible. In this case it is necessary to gather as much information as possible in one experiment.
There are some critical surgical steps in an open-beating heart model like this. To not use pigs unnecessarily, there must be an experienced surgeon to dissect the heart skeleton between the ascending aorta and the pulmonary artery while hemodynamics are unstable due to the pressure on the RV and RA. Another critical step is putting the Millar tip catheter into the pulmonary artery. To get a better exposure of the surgical field, the right ventricular outflow tract (RVOT) needs to be pushed away very gently. With the right amount of pressure, it is possible have good visualibility and stability of the PA. This makes it easier to take small bites with the 5.0 suture and decreases the risk of PA bleeding or injury.
When measuring hemodynamics, losing a great amount of blood and thus changing the hematocrit significantly can influence the measurements and the results20. When placing the catheter into the artery, using a tourniquet first and making a very small incision to fix the catheter quickly could prevent any blood loss. Ensure that all small bleedings are stopped before insertion of the Millar catheter, because electrocautery can damage the catheter (as described in the catheters manual). After closing of the pericardium and the sternum small bleedings can accumulate over time and cause changes in hematocrit or cause a pericardial tamponade with significant changes in hemodynamics. This could cause a termination of the experiment.
When cutting into the LA, one must be careful. The LA is the pacemaker of the heart and it can react with heart rhythm disturbances when touching it with cold metal instruments. Before putting the clamp gently around the LAA, administration of magnesium could prevent atrial fibrillation (AF). Rhythm disturbances like AF have great impact on left as well as right ventricular hemodynamics21.

Right ventricular (RV) dysfunction is a major cause of morbidity and mortality in patients with heart failure1, especially if the underlying cause is pulmonary hypertension2. The RV pumps blood into the low-resistance pulmonary system, which is normally associated with high compliance. Therefore, the RV is characterized by low peak systolic pressure. It also generates one sixth the stroke work compared with the left ventricle (LV)3. Due to its thinner muscle, the RV is very vulnerable to a change in pre- and afterload4,5. The isovolumic phases of contraction and relaxation during systole and diastole in the RV are not as distinct as in the LV. The examination of left and right ventricular hemodynamic parameters is highly important in therapy of critically ill patients with acute right heart distress4,7, because RV failure increases short-term mortality significantly6.
Preload parameters like the central venous pressure (CVP) and left ventricular preload parameters like pulmonary capillary wedge pressure (PCWP) have been used for a long time to determine volume status of patients. Lately, it has been shown that these parameters alone are not suitable to detect a patient&#39;s need of fluids8,9,10. Recognizing fluid responsiveness is essential to detect and treat volume deprivation and volume overload in patients with RV dysfunction. Avoiding volume overload is essential to decrease the mortality and length of intensive care unit (ICU) stay in these patients.
With this study, we established a pig model of right ventricular dysfunction that is consistent and replicable. Due to its similarity to humans, it is necessary to establish consistent and reproducible experimental large animal models of cardiac hemodynamics and measurements for research purpose.

<table><tbody><tr><td>Animal Bio Amp</td><td>ADInstruments</td><td>FE136</td><td></td></tr><tr><td>Quad BridgeAmp</td><td>ADInstruments</td><td>FE224</td><td></td></tr><tr><td>Power Lab 16/35</td><td>ADInstruments</td><td>5761-E</td><td></td></tr><tr><td>LabChart 8.1.8 Windows</td><td>ADInstruments</td><td></td><td></td></tr><tr><td>Pulmonary artery catheter 7 F</td><td>Edwards Lifesciences Corporation</td><td>&amp;nbsp;&amp;nbsp;131F7&amp;nbsp;</td><td></td></tr><tr><td>Prelude Sheath Introducer 8 F</td><td>Merit Medical Systems, Inc.</td><td>SI-8F-11-035</td><td></td></tr><tr><td>COnfidence Cardiac Output Flowprobes</td><td>Transonic</td><td>AU-IFU-PAUProbes-EN Rev. A 4/13</td><td></td></tr><tr><td>Adrenalin</td><td>Sanofi</td><td>6053210</td><td></td></tr><tr><td>Oleic acid</td><td>Sigma Aldrich</td><td>112-80-1</td><td></td></tr><tr><td>Magnesium Verla</td><td>Verla</td><td>7244946</td><td></td></tr><tr><td>Ketamin</td><td>Richter Pharma AG</td><td>BE-V433246</td><td></td></tr><tr><td>Azaperon</td><td>Sanochemia Pharmazeutika AG</td><td>QN05AD90</td><td></td></tr><tr><td>Midazolam</td><td>Roche Pharma AG</td><td>3085793</td><td></td></tr></tbody></table>

invasive hemodynamic monitoring of aortic and pulmonary artery hemodynamics in a large animal model of ards

One of the leading causes of morbidity and mortality in patients with heart failure is right ventricular (RV) dysfunction, especially if it is due to pulmonary hypertension. For a better understanding and treatment of this disease, precise hemodynamic monitoring of left and right ventricular parameters is important. For this reason, it is essential to establish experimental pig models of cardiac hemodynamics and measurements for research purpose. 
This article shows the induction of ARDS by using oleic acid (OA) and consequent right ventricular dysfunction, as well as the instrumentation of the pigs and the data acquisition process that is needed to assess hemodynamic parameters. To achieve right ventricular dysfunction, we used oleic acid (OA) to cause ARDS and accompanied this with pulmonary artery hypertension (PAH). With this model of PAH and consecutive right ventricular dysfunction, many hemodynamic parameters can be measured, and right ventricular volume load can be detected. 
All vital parameters, including respiratory rate (RR), heart rate (HR) and body temperature were recorded throughout the whole experiment. Hemodynamic parameters including femoral artery pressure (FAP), aortic pressure (AP), right ventricular pressure (peak systolic, end systolic and end diastolic right ventricular pressure), central venous pressure (CVP), pulmonary artery pressure (PAP) and left arterial pressure (LAP) were measured as well as perfusion parameters including ascending aortic flow (AAF) and pulmonary artery flow (PAF). Hemodynamic measurements were performed using transcardiopulmonary thermodilution to provide cardiac output (CO). Furthermore, the PiCCO2 system (Pulse Contour Cardiac Output System 2) was used to receive parameters such as stroke volume variance (SVV), pulse pressure variance (PPV), as well as extravascular lung water (EVLW) and global end-diastolic volume (GEDV). Our monitoring procedure is suitable for detecting right ventricular dysfunction and monitoring hemodynamic findings before and after volume administration.

Our animal model shows a broad variety of hemodynamic parameters in pigs. Due to its similarity in size and hemodynamics, one can easily use the exact same equipment as used in humans to get similar results.&#160;However, anesthesia values are based on experience and may change based on weight/ age/ strain of pig.&#160; A veterinarian should be consulted to evaluate anesthetic plan.
Results of previous OA induced acute lung injury (ALI) models were inconsistent13,14,15,16. Former protocols stated that OA has been administered mixing it with blood, normal saline, or purely administering it into the heart, a central vein or a peripheral vein in doses of 0.6&#8211;2 mL/kg bodyweight17,18. We tried all of the above methods and found out that purely administering low doses of OA (0.03&#8211;0.06 mL/kg for about 2 h) achieved the most consistent results of ARDS without losing any animals due to respiratory failure or severe acute right heart failure.
First, we were able to show that the intravenous infusion of OA is an easy and good model to induce ARDS as shown before. Depending on the amount of OA administered, one gets a mild to severe lung injury up to death13. It has been shown that an amount of about 0.1 mL/kg OA is mostly used to have a moderate ALI16,18.
To get a mild to moderate ARDS that can be used for further investigation, it is sufficient to inject 0.03-0.06 mL/kg OA. After the administration of this small amount of OA, the oxygenation index decreased from 516.83 &#177; 50.25 mmHg to 181.19 &#177; 32.25 mmHg (p = 0.0006) (Figure 6). The decrease of oxygenated blood is accompanied with a statistically significant increase in carboxylated blood from 36.71 &#177; 4.51 mmHg to 46.50 &#177; 6.87 mmHg (p = 0.008) (Figure 7).
Pulmonary hypertension is defined as a PAP of more than 25 mmHg, a PCWP (which equals the left arterial pressure) of &#8804; 15 mmHg and a pulmonary vascular resistance (PVR) &#62; 240 dyn &#215; s &#215; cm&#8722;5 19,20,21. There is a prevalence of about 1%17 with this common disease worldwide. The PCWP accurately reflects both normal and elevated LAP and vice versa18. In our open-heart animal model, we used a catheter placed in the left atrial to measure this value, because a PAC placed in the pulmonary artery through the pulmonary flow probe could cause incorrect flow measurements (Figure 5).
For a correct and especially consistent measurement of the PAP, we used a Millar catheter, which is put directly in the PA and placed in the main pulmonary artery (MPA) about 2 cm after the pulmonary valve.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57405/57405fig1.jpg" /> 
Figure 1: For safe and easy airway management during the whole surgery, perform a tracheotomy and placement of an 8.5 tube directly in the trachea. The bigger the inner diameter of the tube, the better for mechanical ventilation during ARDS. The catheters in the right jugular vein and both femoral arteries are placed by ultrasound using Seldinger&#39;s technique. <a href="/files/ftp_upload/57405/57405fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57405/57405fig2.jpg" /> 
Figure 2: After opening the pericardium, push the RV and RAA away gently for better visualization of the aorta and pulmonary artery. Hemodynamics must be monitored closely during these steps due to a decreased cardiac output. Dissect the connective tissue of the cardiac skeleton between the PA and the aorta gently, especially as the PA is very predisposed towards bleeding due to its thinner wall. Choose the right sized chronic lined low probes (mostly 18&#8211;20 mm) to put around the aorta and the pulmonary artery. <a href="/files/ftp_upload/57405/57405fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57405/57405fig3.jpg" /> 
Figure 3: Use a vascular clamp to fix the LAA and to avoid bleeding. For safe and secure surgery, place two purse string sutures around an edge of the LAA, making a small incision and putting the catheter into the heart. Quickly open the clamp to position the catheter approximately 5 cm deep into the left atrium while monitoring the pressure curve. Reposition the catheter as needed. Fix the catheter by using the purse string sutures. <a href="/files/ftp_upload/57405/57405fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57405/57405fig4.jpg" /> 
Figure 4: Very gently put two purse string sutures into the PA. To avoid unnecessary bleeding, use a tourniquet on one of the purse strings. Make a small incision and put the Millar catheter into the pulmonary artery and immediately pull down the tourniquet. Fix it using both sutures. Impose the probe shell on both aortal and pulmonary flow probes. <a href="/files/ftp_upload/57405/57405fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57405/57405fig5.jpg" /> 
Figure 5: Use a patch to close the pericardium. Because opening of the pericardium during cardiac surgery goes along with an increase in CO and stroke work index, we chose to close the pericardium using a patch to maintain hemodynamic conditions similar to the ones prior to surgery19. <a href="/files/ftp_upload/57405/57405fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/57405/57405fig6.jpg" /> 
Figure 6: Since we increased the oxygen fraction due to the pulmonary impairment of the ARDS, the oxygenation index was calculated for each measurement step. We were able to see a decrease from 516.83 &#177; 50.25 mmHg at the baseline measurement (1) to 181.19 &#177; 32.25 mmHg (p = 0.0006) after administration of OA (5). <a href="/files/ftp_upload/57405/57405fig6large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/57405/57405fig7.jpg" /> 
Figure 7: Along with the decrease of oxygenated arterial blood goes a statistically significant increase in carboxylated blood after induction of ARDS. The baseline measurement was at 36.71 &#177; 4.51 mmHg and increased to 46.50 &#177; 6.87 mmHg (p = 0.008) after administration of OA. <a href="/files/ftp_upload/57405/57405fig7large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Invasive Hemodynamic Monitoring of Aortic and Pulmonary Artery Hemodynamics in a Large Animal Model of ARDS at JoVE.com

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

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.

One of the leading causes of morbidity and mortality in patients with heart failure is right ventricular (RV) dysfunction, especially if it is due to ...

invasive-hemodynamic-monitoring-aortic-pulmonary-artery-hemodynamics

Nanyang Technological University

Research

JoVE Journal

Medicine

10.0K Views.  Universitatsklinikum Hamburg-Eppendorf. Deze methode kan helpen bij het beantwoorden van belangrijke vragen op het gebied van intensive care geneeskunde over hemodynamische monitoring, rechts-ventriculaire disfunctie, en ARDS. De belangrijkste voordelen van deze techniek zijn dat het eenvoudig en gemakkelijk te reproduceren is. De implicaties van deze techniek breiden zich uit tot de beoordeling van de status van patiënt in het kritieke gebied van ARDS.Hoewel deze methode inzicht kan geven in ziektepathogenese, monitoring e...

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

Hemodynamic Characterization of Rodent Models of Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle proliferation and obliteration of pulmonary arterioles. This in turn results in right ventricular (RV) failure, with significant morbidity and mortality. Rodent models of PAH, in the mouse and the rat, are important for understanding the pathophysiology underlying this rare disease. Notably, different models of PAH may be associated with different degrees of pulmonary hypertension, RV hypertrophy and RV failure. Therefore, a complete hemodynamic characterization of mice and rats with PAH is critical in determining the effects of drugs or genetic modifications on the disease. 
Here we demonstrate standard procedures for assessment of right ventricular function and hemodynamics in both rat and mouse PAH models. Echocardiography is useful in determining RV function in rats, although obtaining standard views of the right ventricle is challenging in the awake mouse. Access for right heart catheterization is obtained by the internal jugular vein in closed-chest mice and rats. Pressures can be measured using polyethylene tubing with a fluid pressure transducer or a miniature micromanometer pressure catheter. Pressure-volume loop analysis can be performed in the open chest. After obtaining hemodynamics, the rodent is euthanized. The heart can be dissected to separate the RV free wall from the left ventricle (LV) and septum, allowing an assessment of RV hypertrophy using the Fulton index (RV/(LV+S)). Then samples can be harvested from the heart, lungs and other tissues as needed.

Pulmonary arterial hypertension (PAH) is a disease of pulmonary arterioles that leads to their obliteration and the development of right ventricular failure. Rodent models of PAH are critical in understanding the pathophysiology of PAH. Here we demonstrate hemodynamic characterization, with right heart catheterization and echocardiography, in the mouse and rat.

Pulmonary arterial hypertension (PAH) is a rare disease of the pulmonary vasculature characterized by endothelial cell apoptosis, smooth muscle ...

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

Decompensated right ventricular failure (RVF) in pulmonary hypertension (PH) is fatal, with limited medical treatment options. Developing and testing novel therapeutics for PH requires a clinically relevant large animal model of increased pulmonary vascular resistance and RVF. This manuscript discusses the latest development of the previously published ovine PH-RVF model that utilizes left pulmonary artery (PA) ligation and main PA occlusion. This model of PH-RVF is a versatile platform to control not only the disease severity but also the RV&#39;s phenotypic response.
Adult sheep (60-80 kg) underwent left PA (LPA) ligation, placement of main PA cuff, and insertion of RV pressure monitor. PA cuff and RV pressure monitor were connected to subcutaneous ports. Subjects underwent progressive PA banding twice per week for 9 weeks with sequential measures of RV pressure, PA cuff pressures, and mixed venous blood gas (SvO2). At the initiation and endpoint of this model, ventricular function and dimensions were assessed using echocardiography. In a representative group of 12 animal subjects, RV mean and systolic pressure increased from 28 &#177; 5 and 57 &#177; 7 mmHg at week 1, respectively, to 44 &#177; 7 and 93 &#177; 18 mmHg (mean &#177; standard deviation) by week 9. Echocardiography demonstrated characteristic findings of PH-RVF, notably RV dilation, increased wall thickness, and septal bowing. The longitudinal trend of SvO2 and PA cuff pressure demonstrates that the rate of PA banding can be titrated to elicit varying RV phenotypes. A faster PA banding strategy led to a precipitous decline in SvO2 &#60; 65%, indicating RV decompensation, whereas a slower, more paced strategy led to the maintenance of physiologic SvO2 at 70%-80%. One animal that experienced the accelerated strategy developed several liters of pleural effusion and ascites by week 9. This chronic PH-RVF model provides a valuable tool for studying molecular mechanisms, developing diagnostic biomarkers, and enabling therapeutic innovation to manage RV adaptation and maladaptation from PH.

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

Decompensated right ventricular failure (RVF) in pulmonary hypertension (PH) is fatal, with limited medical treatment options. Developing and testing ...

Bioengineering

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

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The morphological and functional phenotyping of the right ventricle is of particular importance in the context of hemodynamic compromise in patients with ARHF. Here, we describe a method to induce ARHF in a previously described large animal model of chronic PH, and to phenotype, dynamically, right ventricular function using the gold standard method (i.e., pressure-volume PV loops) and with a non-invasive clinically available method (i.e., echocardiography). Chronic PH is first induced in pigs by left pulmonary artery ligation and right lower lobe embolism with biological glue once a week for 5 weeks. After 16 weeks, ARHF is induced by successive volume loading using saline followed by iterative pulmonary embolism until the ratio of the systolic pulmonary pressure over systemic pressure reaches 0.9 or until the systolic systemic pressure decreases below 90 mmHg. Hemodynamics are restored with dobutamine infusion (from 2.5 &#181;g/kg/min to 7.5 &#181;g/kg/min). PV-loops and echocardiography are performed during each condition. Each condition requires around 40 minutes for induction, hemodynamic stabilization and data acquisition. Out of 9 animals, 2 died immediately after pulmonary embolism and 7 completed the protocol, which illustrates the learning curve of the model. The model induced a 3-fold increase in mean pulmonary artery pressure. The PV-loop analysis showed that ventriculo-arterial coupling was preserved after volume loading, decreased after acute pulmonary embolism and was restored with dobutamine. Echocardiographic acquisitions allowed to quantify right ventricular parameters of morphology and function with good quality. We identified right ventricular ischemic lesions in the model. The model can be used to compare different treatments or to validate non-invasive parameters of right ventricular morphology and function in the context of ARHF.

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&#160;or to improve the understanding of acute right heart failure pathophysiology.

The development of acute right heart failure (ARHF) in the context of chronic pulmonary hypertension (PH) is associated with poor short-term outcomes. The ...

Simultaneous Electrocardiography Recording and Invasive Blood Pressure Measurement in Rats

For studies related to cardiovascular physiology or pathophysiology, blood pressure (BP) and electrocardiography are basic observational parameters. Research focusing on cardiovascular disease models, potential cardiovascular therapeutic targets or pharmaceutical agents requires assessment of systemic arterial pressure and heart rhythm changes. In situations where radio telemetry systems are not available or affordable, the technique of femoral artery cannulation is an alternative way to obtain intra-arterial pressure waveform recordings and systemic BP measurements. This technique is economical and can be performed with standard equipment in animal facilities. However, invasive arterial pressure recording requires cannulation of small arteries, which can be a challenging surgical skill. Here, we present step-by-step protocols for femoral artery cannulation procedures. Key procedures include the calibration of the data acquisition system, tissue dissection and femoral artery cannulation, and setup of the arterial cannulation system for pressure recording. Surface electrocardiography recording procedures are also included. We also present examples of BP recordings from normotensive and hypertensive rats. This protocol allows reliable direct recordings of systemic BP with simultaneous electrocardiography.

Here, we describe a setup for simultaneous recording of electrocardiography and intra-arterial blood pressure (BP) in experimental rats, which can be done with standard equipment in animal facilities and can be applied to physiological or pharmacological studies to investigate pathogenic or therapeutic mechanisms in cardiovascular medicine.

For studies related to cardiovascular physiology or pathophysiology, blood pressure (BP) and electrocardiography are basic observational parameters. ...

Invasive Hemodynamic Assessment for the Right Ventricular System and Hypoxia-Induced Pulmonary Arterial Hypertension in Mice

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. However, the evaluation of right ventricular pressure (RVP) and pulmonary artery pressure (PAP) remains technically challenging in mice. RVP and PAP are more difficult to measure than left ventricular pressure because of the anatomical differences between the left and right heart systems. In this paper, we describe a stable right heart hemodynamic measurement method and its validation using healthy and PAH mice. This method is based on open-chest surgery and mechanical ventilation support. It is a complicated procedure compared to closed chest procedures. While a well-trained surgeon is required for this surgery, the advantage of this procedure is that it can generate both RVP and PAP parameters at the same time, so it is a preferable procedure for the evaluation of PAH models.

Here, we present a protocol to perform an invasive hemodynamic assessment of the right ventricle and pulmonary artery in mice using an open-chest surgery approach.

Pulmonary arterial hypertension (PAH) is a chronic and severe cardiopulmonary disorder. Mice are a popular animal model used to mimic this disease. ...

Bronchoalveolar Lavage and Oleic Acid-Injection in Pigs as a Double-Hit Model for Acute Respiratory Distress Syndrome (ARDS)

The treatment of ARDS continues to pose major challenges for intensive care physicians in the 21st century with mortality rates still reaching up to 50% in severe cases. Further research efforts are needed to better understand the complex pathophysiology of this disease. There are different well-established animal models to induce acute lung injury but none has been able to adequately mimic the complex pathomechanisms of ARDS. The most crucial factor for the development of this condition is the damage to the alveolar capillary unit. The combination of two well-established lung injury models allow us to mimic in more detail the underlying pathomechanism. Bronchoalveolar lavage (BAL) leads to surfactant depletion as well as alveolar collapse. The repeated instillation of fluid volumes causes subsequent hypoxemia. Surfactant depletion is a key factor of ARDS in humans. BAL is often combined with other lung injury approaches, but not with a second hit followed by oleic acid injection (OAI) yet. Oleic acid injection leads to severely impaired gas exchange, a deterioration of lung mechanics and disruption of the alveolo-capillary barrier. The OAI mimics most of the expected effects of ARDS consisting of extended inflammation of lung tissue with an increase of alveolar leakage and gas exchange impairment. A disadvantage of the combination of different models is the difficulty to determine the influence to the lung injury caused by BAL alone, OAI alone or both together. The model presented in this report represents the combination of BAL and OAI as a new double-hit lung injury model. This new model is easy to implement and an alternative to study different therapeutic approaches in ARDS in the future.

Bronchoalveolar Lavage and Oleic Acid-Injection in Pigs as a Double-Hit Model for Acute Respiratory Distress Syndrome ARDS

Different, complex animal models exist to study the pathophysiology of acute respiratory distress syndrome (ARDS). Bronchoalveolar lavage and oleic acid injection induced lung injury is suitable as a new double-hit animal model for studying the acute respiratory distress syndrome.

The treatment of ARDS continues to pose major challenges for intensive care physicians in the 21st century with mortality rates still reaching up to 50% ...

Surfactant Depletion Combined with Injurious Ventilation Results in a Reproducible Model of the Acute Respiratory Distress Syndrome (ARDS)

Various animal models exist to study the complex pathomechanisms of the acute respiratory distress syndrome (ARDS). These models include pulmo-arterial infusion of oleic acid, infusion of endotoxins or bacteria, cecal ligation and puncture, various pneumonia models, lung ischemia/reperfusion models and, of course, surfactant depletion models, among others. Surfactant depletion produces a rapid, reproducible deterioration of pulmonary gas exchange and hemodynamics and can be induced in anesthetized pigs using repeated lung lavages with 0.9% saline (35 mL/kg body weight, 37 &#176;C). The surfactant depletion model supports investigations with standard respiratory and hemodynamic monitoring with clinically applied devices. But the model suffers from a relatively high recruitability and ventilation with high airway pressures can immediately reduce the severity of the injury by reopening atelectatic lung areas. Thus, this model is not suitable for investigations of ventilator regimes that use high airway pressures. A combination of surfactant depletion and injurious ventilation with high tidal volume/low positive end-expiratory pressure (high Tv/low PEEP) to cause ventilator induced lung injury (VILI) will reduce the recruitability of the resulting lung injury. The advantages of a timely induction and the possibility to perform experimental research in a setting comparable to an intensive care unit are preserved.

Surfactant Depletion Combined with Injurious Ventilation Results in a Reproducible Model of the Acute Respiratory Distress Syndrome ARDS

A combination of surfactant washout using 0.9% saline (35 mL/kg body weight, 37 &#176;C) and high tidal volume ventilation with low PEEP to cause moderate ventilator induced lung injury (VILI) results in experimental acute respiratory distress syndrome (ARDS). This method provides a model of lung injury with low/limited recruitability to study the effect of various ventilation strategies for extended periods.

Various animal models exist to study the complex pathomechanisms of the acute respiratory distress syndrome (ARDS). These models include pulmo-arterial ...

Multiple Intravenous Bolus Dosing and Invasive Hemodynamic Assessment in a Hypoxia-Induced Mouse Pulmonary Artery Hypertension Model

Pulmonary arterial hypertension (PAH) is a progressive life-threatening disease, primarily affecting small pulmonary arterioles of the lung. Currently, there is no cure for PAH. It is important to discover new compounds that can be used to treat PAH. The mouse hypoxia-induced PAH model is a widely used model for PAH research. This model recapitulates human clinical manifestations of PAH Group 3 disease and is an important research tool to evaluate the effectiveness of new experimental therapies for PAH. Research using this model often requires the administration of compounds in mice. For a compound that needs to be given directly into the bloodstream, optimizing intravenous (IV) administration is a key part of the experimental procedures. Ideally, the IV injection system should permit multiple injections over a set time course. Although the mouse hypoxia-induced PAH model is very popular in many laboratories, it is technically challenging to perform multiple IV bolus dosing and invasive hemodynamic assessment in this model. In this protocol, we present step-by-step instructions on how to carry out multiple IV bolus dosing via mouse jugular vein and perform arterial and right ventricle catheterization for hemodynamic assessment in mouse hypoxia-induced PAH model.

This protocol provides a step-by-step procedure for executing multiple intravenous bolus dose administration and invasive hemodynamic monitoring in mice. Investigators can use this protocol for future therapeutic compound screening for pulmonary artery hypertension.

Pulmonary arterial hypertension (PAH) is a progressive life-threatening disease, primarily affecting small pulmonary arterioles of the lung. Currently, ...

Ascending Aortic Banding for Studying Pressure-Overload Induced Heart Failure

A Minimally Invasive Model of Aortic Stenosis in Swine

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological similarities to humans. Efforts have been dedicated to creating a model of pressure-overload induced heart failure, and ascending aortic banding while still supra-coronary and not a perfect mimic of aortic stenosis in humans, closely resembling the human condition.
The purpose of this study is to demonstrate a minimally invasive approach to induce left ventricular pressure overload by placing an aortic band, precisely calibrated with percutaneously introduced high-fidelity pressure sensors. This method represents a refinement of the surgical procedure (3Rs), resulting in homogenous trans-stenotic gradients and reduced intragroup variability. Additionally, it enables swift and uneventful animal recovery, leading to minimal mortality rates. Throughout the study, animals were followed for up to 2 months after surgery, employing transthoracic echocardiography and pressure-volume loop analysis. However, longer follow-up periods can be achieved if desired. This large animal model proves valuable for testing new drugs, particularly those targeting hypertrophy and the structural and functional alterations associated with left ventricular pressure overload.

Author Spotlight: Development of a Minimally Invasive Large-Animal Model for Reliable and Reproducible Cardiovascular Research 

This protocol describes a minimally invasive surgical procedure for ascending aortic banding in swine.

Large animal models of heart failure play an essential role in the development of new therapeutic interventions due to their size and physiological ...

Surgically Induced Cardiac Volume Overload by Aortic Regurgitation in Mouse

Aortic regurgitation (AR) is a common valvular heart disease that exerts volume overload on the heart and represents a global public health problem. Although mice are widely applied to shed light on the mechanisms of cardiovascular disease, mouse models of AR, especially those induced by surgery, are still paucity. Here, a mouse model of AR was described in detail which is surgically induced by disruption of the aortic valves under high-resolution echocardiography. In accordance with regurgitated blood flow, AR mouse hearts present a distinctive and clinically relevant volume overload phenotype, which is characterized by eccentric hypertrophy and cardiac dysfunction, as evidenced by echocardiographic and invasive hemodynamic evaluation. Our proposal, in a reliable and reproducible manner, provides a practical guide on the establishment and assessment of a mouse model of AR for future studies on molecular mechanisms and therapeutic targets of volume overload cardiomyopathy.

This protocol presents a practical guide on the surgery for creation of aortic regurgitation (AR) in the mouse. Assessment of the AR mouse by echocardiography and invasive hemodynamic measurement recapitulates its clinically relevant characteristics of volume overload-induced eccentric hypertrophy, suggesting its promising application in the study of cardiac hypertrophy.

Aortic regurgitation (AR) is a common valvular heart disease that exerts volume overload on the heart and represents a global public health problem. ...

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

Samenvatting

Meer video's verkennen