The authors thank Portuguese Foundation for Science and Technology (FCT), European Union, Quadro de Refer&#234;ncia Estrat&#233;gico Nacional (QREN), Fundo Europeu de Desenvolvimento Regional (FEDER) and Programa Operacional Factores de Competitividade (COMPETE) for funding UnIC (UID/IC/00051/2013) research unit. This project is supported by FEDER through COMPETE 2020 &#8211; Programa Operacional Competitividade E Internacionaliza&#231;&#227;o (POCI), the project DOCNET (NORTE-01-0145-FEDER-000003), supported by Norte Portugal regional operational programme (NORTE 2020), under the Portugal 2020 partnership agreement, through the European Regional Development Fund (ERDF), the project NETDIAMOND (POCI-01-0145-FEDER-016385), supported by European Structural And Investment Funds, Lisbon&#8217;s regional operational program 2020. Daniela Miranda-Silva and Patr&#237;cia Rodrigues are funded by Funda&#231;&#227;o para a Ci&#234;ncia e Tecnologia (FCT) by fellowship grants (SFRH/BD/87556/2012 and SFRH/BD/96026/2013 respectively). &#160;

All animal experiments comply with the Guide for the Care and Use of Laboratory Animals (NIH Publication no. 85&#8211;23, revised 2011) and the Portuguese law on animal welfare (DL 129/92, DL 197/96; P 1131/97). The competent local authorities approved this experimental protocol (018833). Seven-week-old male C57B1/J6 mice were maintained in appropriate cages, with a regular 12/12 h light-dark cycle environment, a temperature of 22 &#176;C and 60% humidity with access to water and a standard diet ad libitum.
1. Preparation of the surgical field
<ol>
	<li>Disinfect the operation site with 70% alcohol and place a disposable operating room table cover over the surgical area.</li>
	<li>Sterilize all the instruments before surgery. 
	NOTE: This procedure requires micro surgical scissors, 2 fine curved forceps, 3 fine straight forceps, a scalpel, small forceps, an angled dissector scissor, a needle holder, an ultrafine ligation aid, 2 hemostats and, lastly, a magnetic fixator retraction system is highly recommended (Figure 1A).</li>
	<li>Curve the tip of a 26 G blunted needle to 90&#176; for an easier approach to the aorta. A 26 G needle will create a 0.45 mm diameter aortic narrowing (Figure 1B).</li>
	<li>Adjust the heating pad temperature to 37 &#177; 0.1 &#176;C.</li>
</ol>
2. Mice preparation and intubation
<ol>
	<li>Anesthetize young C57B1/J6 mice (20-25 g) by inhalation of 8% sevoflurane with 0.5 - 1.0 L/min 100% O2 in a cone tube.</li>
	<li>Check the anesthesia depth using the toe pinch withdrawal reflex.</li>
	<li>Place the mouse at dorsal recumbency on an inclined plate and proceed to orotracheal intubation.</li>
	<li>Move the mouse to the heating pad and quickly connect the orotracheal tube to the ventilator to initiate the mechanical ventilation.</li>
	<li>Adjust the ventilator parameters to a frequency of 160 breaths/min and a tidal volume of 10 mL/kg.</li>
</ol>
3. Preparation for surgery (for both banding and debanding surgeries)
<ol>
	<li>Shave and apply the depilatory cream from the neckline to mid-chest level of the mice.</li>
	<li>Apply ophthalmic gel to the animals&#39;&#160;eyes to prevent drying out of the cornea.</li>
	<li>Place a rectal probe and the oximeter at the paw or tail for monitoring temperature and blood oxygenation, and heart rate, respectively. 
	NOTE: Anesthesia induces significant hypothermia, therefore, it is important to maintain normal body temperature during surgery to avoid a rapid decrease in heart rate.</li>
	<li>Maintain anesthesia with sevoflurane (2.0 - 3.0%). Check the correct level of anesthesia by the lack of the toe-pinch reflex.</li>
	<li>Place the mice in right-lateral decubitus on a heating pad and secure the limbs to the magnetic fixator retraction system with a tape to keep the animal in the correct position during the surgery (Figure 2, Figure 3A).</li>
	<li>Disinfect the mouse chest with 70% alcohol followed by providone-iodine solution.</li>
</ol>
4. Ascending aortic banding surgery
NOTE: For a detailed protocol description, consult 2,3,4,13. &#160;
<ol>
	<li>With a disposable blade, perform a small (~0.5 cm) skin incision on the left side immediately below the axilla level and dissect the skin.</li>
	<li>Gently dissect and separate the pectoralis muscle and other muscle layers until the ribs become visible. Use fine forceps and avoid cutting the muscle.</li>
	<li>Under a microscope, identify the intercostal spaces and open a small incision between the 2nd and 3rd intercostal space with fine forceps.</li>
	<li>Retract the ribs by placing the chest retractor (Figure 2A).</li>
	<li>Use small forceps to gently dissect and separate the thymic lobes until ascending aorta becomes visible. 
	NOTE: Cotton applicators should be handy in case of bleeding. Warm sterile saline should be given subcutaneously in case of significant bleeding (e.g., the mammary artery).</li>
	<li>Use small forceps to gently dissect the aorta. 
	NOTE: Aorta is considered to be dissected when there are no fat or other adhesions around it and it is possible to easily encircle the vessel with a small curve forceps.</li>
	<li>After aortic dissection, place a 7-0 polypropylene ligature around aorta by using ligation aid and curved forceps (Figure 2B).</li>
	<li>Position the blunted 26 G needle parallel to the aorta (tip pointed towards the mice head) (Figure 2B). For mice weighing 20-25 g, this needle induces a reproducible 65-70% aortic constriction.</li>
	<li>Make 2 loose knots around the aorta and the 26 G needle with the help of 2 forceps (Figure 2B).</li>
	<li>Tighten the 1st knot and, quickly after, the 2nd knot. Briefly confirm the right positioning of the constriction and quickly remove the needle to restore aortic blood flow. Finally, make a 3rd knot (BA group).</li>
	<li>Reposition the thymus and the muscles into their initial position.</li>
	<li>Perform the sham procedure identical to the constriction procedure but keeping the suture loose around the aorta (SHAM group).</li>
	<li>Cut the ends of the suture and remove the chest retractor. 
	NOTE: Short suture ends may increase the probability of knots loosening with aortic pressure, while long ends make the debanding procedure riskier since adhesions can occur between the suture and the left atrium.</li>
	<li>Close the chest wall using 6-0 polypropylene suture with a simple interrupted or continuous suture using the lowest number of stitches possible. Tighten the last chest knot with the lungs inflated at end inspiration by pinched off the outflow of the ventilator for 2s to re-inflate the lungs.</li>
	<li>Close the skin with a 6-0 silk/polypropylene suture in a continuous suture pattern.&#160; 
	NOTES: If a more recent ventilator is used, it is possible to programme it to pause in inspiration (Setup-Advanced-Pause-Inspiration)</li>
</ol>
5. Post-operative care
<ol>
	<li>Apply providone-iodine solution to the skin suture site.</li>
	<li>For proper analgesia, administer buprenorphine subcutaneously 0.1 mg/kg, twice daily, until the animal fully recovers (usually 2-3 days after surgery).</li>
	<li>Inject sterile saline intraperitoneally to prevent dehydration in case of significant bleeding during the surgery.</li>
	<li>Turn off the anesthesia (without deintubating the mouse) and wait until the animal recover the reflexes (whiskers movements are an awakening signal)&#160; and starts to breathe spontaneously.</li>
	<li>Remove the tracheal cannula.</li>
	<li>Let the animal recover in an incubator at 37 &#176;C.</li>
	<li>Return the animal to a 12 h light/dark cycle room after full recovery.</li>
</ol>
6. Aortic debanding surgery
<ol>
	<li>Seven weeks later, perform the debanding of the aorta in half of the BA&#160; animals and remove the loose suture from half of the SHAM mice, giving rise to 2 new groups --&#160;debanding (DEB) and debanding SHAMA (DESHAM), respectively. DESHAM&#160;represents the control for the DEB group (Figure 4).</li>
	<li>Repeat all the steps 2.1 to 3.6 mentioned above.</li>
	<li>Gently dissect the tissues, adhesions, and fibrosis around the aorta until its constriction becomes visible.</li>
	<li>Carefully dissect the aorta and separate the suture from the aorta. Cut the suture with angled one-probed spring scissors (Figure 3B).</li>
	<li>Close the chest wall using 6-0 polypropylene suture with a simple interrupted or continuous suture using the minimum number of stitches possible. 
	NOTE: Try to tighten the last chest suture when lungs are inflated to avoid pneumothorax.</li>
	<li>Close the skin with a 6-0 silk/polypropylene suture in a continuous suture pattern.&#160;</li>
	<li>Perform all post-operative care procedures as mentioned in 5.</li>
	<li>Sacrifice the animals 2 weeks later.</li>
</ol>
7. Echocardiography to assess cardiac function and left ventricular hypertrophy in vivo
<ol>
	<li>Perform the echocardiographic exam every 2-3 weeks to follow the progression of hypertrophy and cardiac function.</li>
	<li>Anesthetize the animals, as described, by inhalation of 5% sevoflurane with a nose cone. Adjust the anesthesia level by decreasing it to 2.5%.</li>
	<li>Shave and apply the depilatory cream from the neckline to mid-chest level.</li>
	<li>Place the animal on a heating pad and place the ECG electrodes. Assure a good ECG trace and maintain heart rate between 300 and 350 beats/min.</li>
	<li>Monitor the temperature (~37 &#176;C).</li>
	<li>Apply echo gel and position the animal at left lateral decubitus.</li>
	<li>Start the echocardiograph and adjust the settings.</li>
	<li>Position an ultrasound probe over the thorax.</li>
	<li>Assess the pressure gradient across the banding at 7 and 2 weeks after banding and debanding surgery, respectively. Position the probe at the LV long axis and place the beam over aorta. Press the button PW to activate pulsed wave Doppler echocardiography. After seven weeks of banding, aortic gradients will be &#62;25 mmHg in the banded animals.</li>
	<li>Record two-dimensional guided images of aorta showing the presence or absence of the ascending aorta constriction to anatomically visualize the efficacy of the banding and debanding. 
	NOTE: It is possible to visualize turbulent flow at the constriction level if the color mode is available.</li>
	<li>Assess hypertrophy by positioning the probe at an LV short axis, at papillary muscles level, and press M-mode tracing to visualize LV anterior wall (LVAW), LV diameter (LVD) and LV posterior wall (LVPW) in diastole (D) and systole (S) (Figure 5).</li>
	<li>Assess systolic function, calculate the ejection fraction and fractional shortening as previously described14,15.</li>
	<li>Assess diastolic function by 1) determining the peak of pulsed-wave Doppler of early and late mitral flow velocity (E and A waves, respectively) using an apical 4-chamber apical view just above the mitral leaflets; 2) recording lateral mitral annular myocardial early diastolic (E&#39;) and peak systolic (S&#39;) velocities using pulsed-TDI and apical 4-chamber apical view (Figure 5). &#160;</li>
	<li>Record at least three consecutive heartbeats to each parameter assessment. These values will be subsequently averaged.</li>
</ol>
8. Hemodynamic assessment
<ol>
	<li>At the end of the protocol (Figure 4), perform final echocardiography, as described in 7, before the terminal hemodynamic assessment.</li>
	<li>Repeat steps 2.1 to 3.6.</li>
	<li>Cannulate the right jugular vein and perfuse sterile saline at 64 mL/kg/h.</li>
	<li>Rotate slightly the animal to the left side and make a skin incision at the level of the xiphoid appendix.</li>
	<li>Separate the skin from the muscle with forceps or with a scissor.</li>
	<li>Make a lateral incision between the left ribs at the xiphoid appendix level.</li>
	<li>Perform a left lateral thoracotomy to expose the heart fully. 
	NOTE: To avoid bleeding and lung damage, insert a cotton swab into the thoracic cavity and push the lung gently while inserting two hemostats on the right and left side of the place to cut.</li>
	<li>Pre-heat the P-V loop catheters in a water-bath at 37 &#176;C.</li>
	<li>Calibrate the catheter (setup, channel setting, chose the correct channel for pressure and volume, units).</li>
	<li>Insert a catheter apically into the LV and assure the volume sensors are positioned between the aortic valve and the apex. Volumes can be assessed by echocardiography (Figure 5). Visualization of the pressure-volume loops helps to confirm the correct positioning of the catheter (Figure 6).</li>
	<li>Allow the animal to stabilize 20-30 min without significant changes in the shape of the pressure-volume loops.</li>
	<li>With ventilation suspended at end-expiration, acquire baseline recordings (Figure 6). Continuously acquire data at 1,000 Hz to be subsequently analyzed off-line by appropriate software.</li>
	<li>Compute parallel conductance after the hypertonic saline bolus (10%, 10 &#181;L).</li>
	<li>While anesthetized, sacrifice the animal by exsanguination, collect and centrifuge the blood.</li>
	<li>Lastly, excise and collect&#160;the heart. Weight the heart, the left, and the right ventricle separately and immediately store the samples in liquid nitrogen or formalin for subsequent molecular or histological studies, respectively.</li>
</ol>
9. Aortic banding/debanding procedure in rats
<ol>
	<li>Perform aortic banding in young Wistar (70-90 g) using a 22 G needle and 6-0 polypropylene ligature to constrict the aorta.</li>
	<li>Ensure a proper anesthetic and analgesic procedures with 3-4% of sevoflurane and 0.05&#8201;mg/kg of buprenorphine, respectively.</li>
	<li>During echocardiography, assure a heart rate always above 300 rate / min (ideally between 300 and 350).</li>
	<li>Before step 8.9, gently dissect the rat aorta, place a flow probe around it to measure cardiac output. The use of the aortic flow probe is the gold standard procedure for rats.</li>
	<li>For the hemodynamic evaluation, cannulate the jugular or femoral vein for fluid administration (32 mL/kg/h).</li>
	<li>Replace the pressure-volume catheter SPR-1035 by the SPR-847 or SPR-838, whose sizes better suit the rat ventricular dimensions.</li>
</ol>

<ol>
	<li>Arany, Z., 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=Transverse+aortic+constriction+leads+to+accelerated+heart+failure+in+mice+lacking+PPAR-gamma+coactivator+1alpha.">Transverse aortic constriction leads to accelerated heart failure in mice lacking PPAR-gamma coactivator 1alpha.</a> Proceedings of the National Academy of Science U. S. A. 103 (26), 10086-10091 (2006).</li><li>Tavakoli, R., Nemska, S., Jamshidi, P., Gassmann, M., Frossard, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technique+of+Minimally+Invasive+Transverse+Aortic+Constriction+in+Mice+for+Induction+of+Left+Ventricular+Hypertrophy.">Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy.</a> Journal of Visualized Experiment. (127), e56231 (2017).</li><li>Zaw, A. M., Williams, C. M., Law, H. K., Chow, B. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimally+Invasive+Transverse+Aortic+Constriction+in+Mice.">Minimally Invasive Transverse Aortic Constriction in Mice.</a> Journal of Visualized Experiment. (121), e55293 (2017).</li><li>Rockman, H. A., 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=Segregation+of+atrial-specific+and+inducible+expression+of+an+atrial+natriuretic+factor+transgene+in+an+in+vivo+murine+model+of+cardiac+hypertrophy.">Segregation of atrial-specific and inducible expression of an atrial natriuretic factor transgene in an in vivo murine model of cardiac hypertrophy.</a> Proceedings of the National Academy of Science. 88 (18), 8277-8281 (1991).</li><li>Koide, 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=Premorbid+determinants+of+left+ventricular+dysfunction+in+a+novel+model+of+gradually+induced+pressure+overload+in+the+adult+canine.">Premorbid determinants of left ventricular dysfunction in a novel model of gradually induced pressure overload in the adult canine.</a> Circulation. 95 (6), 1601-1610 (1997).</li><li>Rodrigues, P. G., Leite-Moreira, A. F., Falcao-Pires, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+reverse+remodeling:+how+far+can+we+rewind.">Myocardial reverse remodeling: how far can we rewind.</a> American Journal of Physiology-Heart and Circulatory Physiology. 310 (11), 1402-1422 (2016).</li><li>Weidemann, F., 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+myocardial+fibrosis+in+patients+with+symptomatic+severe+aortic+stenosis.">Impact of myocardial fibrosis in patients with symptomatic severe aortic stenosis.</a> Circulation. 120 (7), 577-584 (2009).</li><li>Bing, 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=Imaging+and+Impact+of+Myocardial+Fibrosis+in+Aortic+Stenosis.">Imaging and Impact of Myocardial Fibrosis in Aortic Stenosis.</a> JACC Cardiovascular Imaging. 12 (2), 283-296 (2019).</li><li>Conceicao, G., Heinonen, I., Lourenco, A. P., Duncker, D. J., Falcao-Pires, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+heart+failure+with+preserved+ejection+fraction.">Animal models of heart failure with preserved ejection fraction.</a> Netherlands Heart Journal. 24 (4), 275-286 (2016).</li><li>Weinheimer, C. J., 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=Load-Dependent+Changes+in+Left+Ventricular+Structure+and+Function+in+a+Pathophysiologically+Relevant+Murine+Model+of+Reversible+Heart+Failure.">Load-Dependent Changes in Left Ventricular Structure and Function in a Pathophysiologically Relevant Murine Model of Reversible Heart Failure.</a> Circulation Heart Failure. 11 (5), 004351 (2018).</li><li>Bjornstad, J. L., 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+mouse+model+of+reverse+cardiac+remodelling+following+banding-debanding+of+the+ascending+aorta.">A mouse model of reverse cardiac remodelling following banding-debanding of the ascending aorta.</a> Acta Physiologica (Oxford). 205 (1), 92-102 (2012).</li><li>Yarbrough, W. M., Mukherjee, R., Ikonomidis, J. S., Zile, M. R., Spinale, F. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Myocardial+remodeling+with+aortic+stenosis+and+after+aortic+valve+replacement:+mechanisms+and+future+prognostic+implications.">Myocardial remodeling with aortic stenosis and after aortic valve replacement: mechanisms and future prognostic implications.</a> Journal of Thoracic and Cardiovascular Surgery. 143 (3), 656-664 (2012).</li><li>deAlmeida, A. C., van Oort, R. J., Wehrens, X. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transverse+aortic+constriction+in+mice.">Transverse aortic constriction in mice.</a> Journal of Visualized Experiment. (38), 1729 (2010).</li><li>Hamdani, 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=Myocardial+titin+hypophosphorylation+importantly+contributes+to+heart+failure+with+preserved+ejection+fraction+in+a+rat+metabolic+risk+model.">Myocardial titin hypophosphorylation importantly contributes to heart failure with preserved ejection fraction in a rat metabolic risk model.</a> Circulation: Heart Failure. 6 (6), 1239-1249 (2013).</li><li>Li, L., 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=Assessment+of+Cardiac+Morphological+and+Functional+Changes+in+Mouse+Model+of+Transverse+Aortic+Constriction+by+Echocardiographic+Imaging.">Assessment of Cardiac Morphological and Functional Changes in Mouse Model of Transverse Aortic Constriction by Echocardiographic Imaging.</a> Journal of Visualized Experiment. (112), e54101 (2016).</li><li>Lygate, C. A., 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=Serial+high+resolution+3D-MRI+after+aortic+banding+in+mice:+band+internalization+is+a+source+of+variability+in+the+hypertrophic+response.">Serial high resolution 3D-MRI after aortic banding in mice: band internalization is a source of variability in the hypertrophic response.</a> Basic Research in Cardiology. 101 (1), 8-16 (2006).</li><li>Platt, M. J., Huber, J. S., Romanova, N., Brunt, K. R., Simpson, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathophysiological+Mapping+of+Experimental+Heart+Failure:+Left+and+Right+Ventricular+Remodeling+in+Transverse+Aortic+Constriction+Is+Temporally,+Kinetically+and+Structurally+Distinct.">Pathophysiological Mapping of Experimental Heart Failure: Left and Right Ventricular Remodeling in Transverse Aortic Constriction Is Temporally, Kinetically and Structurally Distinct.</a> Frontiers in Physiology. 9, 472 (2018).</li><li>Garcia-Menendez, L., Karamanlidis, G., Kolwicz, S., Tian, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Substrain+specific+response+to+cardiac+pressure+overload+in+C57BL/6+mice.">Substrain specific response to cardiac pressure overload in C57BL/6 mice.</a> American Journal of Physiology-Heart and Circulation Physiology. 305 (3), 397-402 (2013).</li><li>Melleby, A. O., 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+novel+method+for+high+precision+aortic+constriction+that+allows+for+generation+of+specific+cardiac+phenotypes+in+mice.">A novel method for high precision aortic constriction that allows for generation of specific cardiac phenotypes in mice.</a> Cardiovascular Research. 114 (12), 1680-1690 (2018).</li><li>Li, Y. H., 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=Effect+of+age+on+peripheral+vascular+response+to+transverse+aortic+banding+in+mice.">Effect of age on peripheral vascular response to transverse aortic banding in mice.</a> The Journal of Gerontology. Series A, Biological Sciences and Medical Sciences. 58 (10), 895-899 (2003).</li><li>Ruppert, 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=Myocardial+reverse+remodeling+after+pressure+unloading+is+associated+with+maintained+cardiac+mechanoenergetics+in+a+rat+model+of+left+ventricular+hypertrophy.">Myocardial reverse remodeling after pressure unloading is associated with maintained cardiac mechanoenergetics in a rat model of left ventricular hypertrophy.</a> American Journal of Physiology-Heart and Circulation Physiology. 311 (3), 592-603 (2016).</li><li>Treibel, T. A., 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=Reverse+Myocardial+Remodeling+Following+Valve+Replacement+in+Patients+With+Aortic+Stenosis.">Reverse Myocardial Remodeling Following Valve Replacement in Patients With Aortic Stenosis.</a> Journal of the American College of Cardiology. 71 (8), 860-871 (2018).</li><li>Dadson, 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=Cellular,+structural+and+functional+cardiac+remodelling+following+pressure+overload+and+unloading.">Cellular, structural and functional cardiac remodelling following pressure overload and unloading.</a> International Journal of Cardiology. 216, 32-42 (2016).</li><li>Krayenbuehl, H. P., 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=Left+ventricular+myocardial+structure+in+aortic+valve+disease+before,+intermediate,+and+late+after+aortic+valve+replacement.">Left ventricular myocardial structure in aortic valve disease before, intermediate, and late after aortic valve replacement.</a> Circulation. 79 (4), 744-755 (1989).</li><li>McCann, G. P., Singh, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Revisiting+Reverse+Remodeling+After+Aortic+Valve+Replacement+for+Aortic+Stenosis.">Revisiting Reverse Remodeling After Aortic Valve Replacement for Aortic Stenosis.</a> Journal of the American College of Cardiology. 71 (8), 872-874 (2018).</li><li>Miranda-Silva, D., 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=Characterization+of+biventricular+alterations+in+myocardial+(reverse)+remodelling+in+aortic+banding-induced+chronic+pressure+overload.">Characterization of biventricular alterations in myocardial (reverse) remodelling in aortic banding-induced chronic pressure overload.</a> Science Reports. 9 (1), 2956 (2019).</li></ol>

The authors have no conflict of interest.

The model proposed herein mimics the process of LV remodeling and RR after aortic banding and debanding, respectively. Therefore, it represents an excellent experimental model to advance our knowledge on the molecular mechanisms involved in the adverse LV remodeling and to test novel therapeutic strategies able to induce myocardial recovery of these patients. This protocol details steps on how to create a rodent animal model of aortic banding and debanding with a minimally invasive and highly conservative surgical techni...

The constriction of the transverse or ascending aorta in the mouse is a widely used experimental model for pressure overload-induced cardiac hypertrophy, diastolic and systolic dysfunction and heart failure1,2,3,4. Aortic-constriction initially leads to compensated left ventricle (LV) concentric hypertrophy to normalize wall stress1. However, under certain circumstances, such as prolonged cardiac overload, this hypertrophy is insufficient to decrease the wall stress, triggering diastolic and systolic dysfunction (pathological hypertrophy)5. In parallel, changes in extracellular matrix (ECM) lead to the collagen deposition and crosslinking in a process known as fibrosis, which can be subdivided into replacement fibrosis and reactive fibrosis. Fibrosis is, in most of the cases, irreversible and compromises myocardial recovery after overload relief6,7. Nevertheless, recent cardiac magnetic resonance imaging studies revealed that reactive fibrosis is able to regress in the long term8. Altogether, fibrosis, hypertrophy and cardiac dysfunction are part of a process known as myocardial remodeling that rapidly progresses towards heart failure (HF).
Understanding the features of myocardial remodeling has become a major objective for limiting or reversing its progression, the latter known as reverse remodeling (RR). The term RR includes any myocardial alteration chronically reversed by a given intervention, such pharmacological therapy (e.g., antihypertensive medication), valve surgery (e.g., aortic stenosis) or ventricular assist devices (e.g., chronic HF). However, RR is often incomplete due to the prevailing hypertrophy or systolic/diastolic dysfunction. Thus, the clarification of RR underlying mechanisms and novel therapeutic strategies are still missing, which is mostly due to the impossibility to access and study human myocardial tissue during RR in most of these patients.
To overcome this limitation, rodent models have played a significant role in advancing our understanding of the signaling pathways involved in HF progression. Specifically, aortic debanding of mice with an aortic constriction represents a useful model to study the molecular mechanisms underlying adverse LV remodeling9 and RR10,11 as it allows the collection of myocardial samples at different time points in these two phases. Moreover, it provides an excellent experimental setting to test potential novel targets that can promote/accelerate RR. For instance, in aortic stenosis context, this model might provide information about the molecular mechanisms involved in the vast diversity of myocardial response underlying the (in)completeness of the RR6,12, as well as, the optimal timing for valve replacement, which represents a major shortcoming of the current knowledge. Indeed, the optimal timing for this intervention is a subject of debate, mainly because it is defined based on the magnitude of aortic gradients. Several studies advocate that this time point might be too late for the myocardial recovery as fibrosis and diastolic dysfunction are often already present12.
To our knowledge, this is the only animal model that recapitulates the process of both myocardial remodeling and RR taking place in conditions such as aortic stenosis or hypertension before and after valve replacement or the onset of anti-hypertensive medication, respectively.
Seeking to address the challenges summarized above, we describe a surgical animal model that can be implemented both in mice and rats, addressing the differences between these two species. We describe the main steps and details involved when carrying out these surgeries. Finally, we report the most significant changes taking place in the LV immediately before and throughout RR.

<table border="0" cellpadding="0" cellspacing="0" style="width:965px;" width="964">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Absorption Spears</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">18105-03</td>
			<td style="width:393px;">To absorb fluids during the surgery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Blades</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">10011-00</td>
			<td>To perform the skin incision</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Buprenorphine</td>
			<td style="width:145px;">Buprelieve</td>
			<td style="width:161px;"></td>
			<td>Analgesia drug</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Catutery</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">18010-00</td>
			<td style="width:393px;">To prevent exsanguination</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Catutery tips</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">18010-01</td>
			<td style="width:393px;">To prevent exsanguination</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">cotton swab</td>
			<td style="width:145px;">Johnson&#39;s</td>
			<td style="width:161px;"></td>
			<td style="width:393px;">To absorb fluids during the surgery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Depilatory cream</td>
			<td style="width:145px;">Veet</td>
			<td style="width:161px;"></td>
			<td>To delipate the animal</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:18px;">Disposable operating room table cover</td>
			<td style="width:145px;">MEDKINE</td>
			<td style="width:161px;">DYND4030SB</td>
			<td>To cover the surgical area</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Echo probe</td>
			<td style="width:145px;">Siemens</td>
			<td>Sequoia 15L8W</td>
			<td>Ultrasound signal aquisition</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Echocardiograph</td>
			<td style="width:145px;">Siemens</td>
			<td>Acuson Sequoia C512</td>
			<td>Ultrasound signal aquisition</td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:265px;">End-tidal CO2 monitor</td>
			<td style="width:145px;">Kent Scientific</td>
			<td style="width:161px;">CapnoStat</td>
			<td>To control expiration gas saturation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Forcep/Tweezers</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">11255-20</td>
			<td>To dissect the tissues and aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Forcep/Tweezers</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">11272-30</td>
			<td>To dissect the tissues and aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Forcep/Tweezers</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">11151-10</td>
			<td>To dissect the tissues and aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Forcep/Tweezers</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">11152-10</td>
			<td>To dissect the tissues and aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Gas system</td>
			<td>Penlon Sigma Delta</td>
			<td style="width:161px;"></td>
			<td>To anesthesia and mechanical ventilation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Hemostats</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">13010-12</td>
			<td>To hold the suture before tight the aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Hemostats</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">13011-12</td>
			<td>To hold the suture before tight the aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Ligation aids</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">18062-12</td>
			<td>To place a suture around the aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Magnetic retractor</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">18200-20</td>
			<td>To help keep the animal in a proper position</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Needle holder</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">12503-15</td>
			<td>To suture the animal</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Needle 26G</td>
			<td style="width:145px;">B-BRAUN</td>
			<td style="width:161px;">4665457</td>
			<td>To serve as a molde of aortic constriction diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Oxygen</td>
			<td style="width:145px;">Air Liquide</td>
			<td style="width:161px;"></td>
			<td>To anesthesia and mechanical ventilation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Polipropilene suture</td>
			<td style="width:145px;">Vycril</td>
			<td style="width:161px;">W8304/W8597</td>
			<td>To suture the animal and to do the constriction</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;">Povidone-iodine solution</td>
			<td style="width:145px;">Betadine&#174;</td>
			<td style="width:161px;"></td>
			<td>Skin antiseptic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">PowerLab</td>
			<td>Millar instruments</td>
			<td>ML880 PowerLab 16/30</td>
			<td>PV loop Signal Aquisition</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Pulse oximeter</td>
			<td style="width:145px;">Kent Scientific</td>
			<td style="width:161px;">MouseStat</td>
			<td>To control heart rate and blood saturation</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">PVAN software</td>
			<td style="width:145px;">Millar Instruments</td>
			<td style="width:161px;"></td>
			<td>To analyse the haemodynamic data</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">PV loop cathether</td>
			<td>Millar instruments</td>
			<td>SPR-1035. 1.4 F</td>
			<td>PV loop Signal Aquisition</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Retractor</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">17000-01</td>
			<td>To provide a better overview of the aorta</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Scalpet handle</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">10003-12</td>
			<td>To perform the skin incision</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Scissors</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">15070-08</td>
			<td>To cut the suture in debanding surgery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Scissors</td>
			<td style="width:145px;">F.S.T</td>
			<td style="width:161px;">14084-09</td>
			<td>To cut other material during the surgery e.g. suture, papper</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Sevoflurane</td>
			<td style="width:145px;">Baxter</td>
			<td style="width:161px;">533-CA2L9117</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Temperature control module</td>
			<td style="width:145px;">Kent Scientific</td>
			<td style="width:161px;">RightTemp</td>
			<td>To control animal corporal temperature</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:265px;">Ventilator</td>
			<td style="width:145px;">Kent Scientific</td>
			<td style="width:161px;">PhysioSuite</td>
			<td>To ventilate the animal</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Water-bath</td>
			<td style="width:145px;">Thermo Scientific&#8482;</td>
			<td style="width:161px;">TSGP02</td>
			<td>To maintain water temperature adequate to heat the P-V loop catethers</td>
		</tr>
	</tbody>
</table>

studying left ventricular reverse remodeling by aortic debanding in rodents

To better understand the left ventricular (LV) reverse remodeling (RR), we describe a rodent model wherein, after aortic banding-induced LV remodeling, mice undergo RR upon removal of the aortic constriction. In this paper, we describe a step-by-step procedure to perform a minimally invasive surgical aortic debanding in mice. Echocardiography was subsequently used to assess the degree of cardiac hypertrophy and dysfunction during LV remodeling and RR and to determine the best timing for aortic debanding. At the end of the protocol, terminal hemodynamic evaluation of the cardiac function was conducted, and samples were collected for histological studies. We showed that debanding is associated with surgical survival rates of 70-80%. Moreover, two weeks after debanding, the significant reduction of ventricular afterload triggers the regression of ventricular hypertrophy (~20%) and fibrosis (~26%), recovery of diastolic dysfunction as assessed by the normalization of left ventricular filling and end-diastolic pressures (E/e&#39;&#160;and LVEDP). Aortic debanding is a useful experimental model to study LV RR in rodents. The extent of myocardial recovery is variable between subjects, therefore, mimicking the diversity of RR that occurs in the clinical context, such as aortic valve replacement. We conclude that the aortic banding/debanding model represents a valuable tool to unravel novel insights into the mechanisms of RR, namely the regression of cardiac hypertrophy and the recovery of diastolic dysfunction.

Post-operative and late survival 
The perioperative survival of the banding procedure is 80% and the mortality during the first month is typically &#60;20%. As previously mentioned, the success of the debanding surgery is highly dependent on how invasive the previous surgery was. After a learning curve, the mortality rate during the debanding procedures is around 25%. For this mortality accounts mostly deaths during the surgery procedure, including aorta or left atrium rupture (in rats, the survival...

Watch this Scientific Journal Video about Studying Left Ventricular Reverse Remodeling by Aortic Debanding in Rodents at JoVE.com

Studying Left Ventricular Reverse Remodeling by Aortic Debanding in Rodents

Here we describe a step-by-step protocol of surgical aorta debanding in the well-established mice model of aortic-constriction. This procedure not only allows studying the mechanisms underlying the left ventricular reverse remodeling and regression of hypertrophy but also to test novel therapeutic options that might accelerate myocardial recovery.

To better understand the left ventricular (LV) reverse remodeling (RR), we describe a rodent model wherein, after aortic banding-induced LV remodeling, ...

studying-left-ventricular-reverse-remodeling-aortic-debanding

Research

JoVE Journal

Medicine

5.0K Views.  Universidade do Porto. Here we describe a step-by-step protocol of surgical aorta debanding in the well-established mice model of aortic-constriction. This procedure not only allows studying the mechanisms underlying the left ventricular reverse remodeling and regression of hypertrophy but also to test novel therapeutic options that might accelerate myocardial recovery.

Video: Studying Left Ventricular Reverse Remodeling by Aortic Debanding in Rodents

Reverse Total Shoulder Arthroplasty

Reverse total shoulder arthroplasty was initially approved for use in rotator cuff arthropathy and well as chronic pseudoparalysis without arthritis in patients who were not appropriate for tendon transfer reconstructions. Traditional surgical options for these patients were limited and functional results were sub-optimal and at times catastrophic. The use of reverse shoulder arthroplasty has been found to effectively restore these patients function and relieve symptoms associated with their disease. The procedure can be done through two approaches, the deltopectoral or the superolateral. Complication rates associated with the use of the prosthesis have ranged from 8-60% with more recent reports trending lower as experienced is gained. Salvage options for a failed reverse shoulder prosthesis are limited and often have significant associated disability. Indications for the use of this prosthesis continue to be evaluated including its use for revision arthroplasty, proximal humeral fracture and tumor. Careful patient selection is essential because of the significant risks associated with the procedure.

Reverse total shoulder arthroplasty is indicated for the treatment of conditions that cannot be treated with conventional arthroplasty or other procedures. These primarily include degenerative and incapacitating conditions with irreparable rotator cuff and loss of the normal biomechanical coupling of the shoulder.

Reverse total shoulder arthroplasty was initially approved for use in rotator cuff arthropathy and well as chronic pseudoparalysis without arthritis in ...

Reduction in Left Ventricular Wall Stress and Improvement in Function in Failing Hearts using Algisyl-LVR

Injection of Algisyl-LVR, a treatment under clinical development, is intended to treat patients with dilated cardiomyopathy. This treatment was recently used for the first time in patients who had symptomatic heart failure. In all patients, cardiac function of the left ventricle (LV) improved significantly, as manifested by consistent reduction of the LV volume and wall stress. Here we describe this novel treatment procedure and the methods used to quantify its effects on LV wall stress and function.
Algisyl-LVR is a biopolymer gel consisting of Na+-Alginate and Ca2+-Alginate. The treatment procedure was carried out by mixing these two components and then combining them into one syringe for intramyocardial injections. This mixture was injected at 10 to 19 locations mid-way between the base and apex of the LV free wall in patients.
Magnetic resonance imaging (MRI), together with mathematical modeling, was used to quantify the effects of this treatment in patients before treatment and at various time points during recovery. The epicardial and endocardial surfaces were first digitized from the MR images to reconstruct the LV geometry at end-systole and at end-diastole. Left ventricular cavity volumes were then measured from these reconstructed surfaces.
Mathematical models of the LV were created from these MRI-reconstructed surfaces to calculate regional myofiber stress. Each LV model was constructed so that 1) it deforms according to a previously validated stress-strain relationship of the myocardium, and 2) the predicted LV cavity volume from these models matches the corresponding MRI-measured volume at end-diastole and end-systole. Diastolic filling was simulated by loading the LV endocardial surface with a prescribed end-diastolic pressure. Systolic contraction was simulated by concurrently loading the endocardial surface with a prescribed end-systolic pressure and adding active contraction in the myofiber direction. Regional myofiber stress at end-diastole and end-systole was computed from the deformed LV based on the stress-strain relationship.

This article describes procedures for implanting a novel hydrogel in failing hearts and quantifying its effect on left ventricular wall stress and function. These procedures have been successfully applied in dogs and humans.

Injection of  Algisyl-LVR, a treatment under clinical development, is intended to treat  patients with dilated cardiomyopathy. This treatment was recently ...

Retinal Detachment Model in Rodents by Subretinal Injection of Sodium Hyaluronate

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the occurrence of subretinal hemorrhage can affect photoreceptor cell death in the detached retina. Hence, it is advantageous to create reproducible RDs without subretinal hemorrhage for evaluating photoreceptor cell death. We modified a previously reported method to create bullous and persistent RDs in a reproducible location with rare occurrence of subretinal hemorrhage. The critical step of this modified method is the creation of a self-sealing scleral incision, which can prevent leakage of sodium hyaluronate after injection into the subretinal space. To make the self-sealing scleral incision, a scleral tunnel is created, followed by scleral penetration into the choroid with a 30 G needle. Although choroidal hemorrhage may occur during this step, astriction with a surgical spear reduces the rate of choroidal hemorrhage. This method allows a more reproducible and reliable model of photoreceptor death in diseases that involve RD such as rhegmatogenous RD, retinopathy of prematurity, diabetic retinopathy, central serous chorioretinopathy, and age-related macular degeneration (AMD).

Creating experimental retinal detachments with a reproducible and sustained height of detachment, and without subretinal hemorrhage, is important for studying the pathophysiology of photoreceptor cell loss in retinal disease and evaluating potential therapeutic interventions. Here, we report such a method in detail.

Subretinal injection of sodium hyaluronate is a widely accepted method of inducing retinal detachment (RD). However, the height and duration of RD or the ...

Transthoracic Speckle Tracking Echocardiography for the Quantitative Assessment of Left Ventricular Myocardial Deformation

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the examiners&#39; expertise. Speckle tracking Echocardiography (STE) is a promising but technically challenging method that can be used to quantitatively assess regional and global systolic and diastolic myocardial performance. Myocardial strain and strain rate can be measured in all three dimensions&#160;&#8212; radial, circumferential, longitudinal &#8212; of myocardial deformation. Standard cross-sectional two-dimensional B-mode images are recorded and subsequently postprocessed by automated continuous frame-by-frame tracking and motion analysis of speckles within the myocardium. Images are recorded as digital loops and synchronized to a 3-lead EKG for timing purposes. Longitudinal deformation is assessed in the apical 4-, 3-, and 2-chamber views. Circumferential and radial deformation are measured in the parasternal short axis plane.
Optimal image quality and accurate tissue tracking are paramount for the correct determination of myocardial performance parameters. Utilizing transthoracic STE in a healthy volunteer, the present article is a detailed outline of the essential steps and potential pitfalls of quantitative echocardiographic myocardial deformation analysis.

Speckle tracking echocardiography is an emerging diagnostic imaging technique for the quantitative assessment of global and regional myocardial performance. Standard view echocardiographic motion images are recorded and deformation parameters are subsequently measured by automated continuous frame-by-frame tracking and motion analysis of speckles within the B-mode images of the myocardium.

The value of conventional echocardiography is limited by differences in inter-individual image interpretation and therefore largely dependent on the ...

Reproducible Arterial Denudation Injury by Infrarenal Abdominal Aortic Clamping in a Murine Model

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These complications can be attributed to impairments in re-endothelialization within the wound margins. Yet, the cellular and molecular mechanisms of re-endothelialization remain to be defined. While several animal models to study re-endothelialization after arterial denudation are available, few are performed in the mouse because of surgical limitations. This undermines the opportunity to exploit transgenic mouse lines and investigate the contribution of specific genes to the process of re-endothelialization. Here, we present a step-by-step protocol for creating a highly reproducible murine model of arterial denudation injury in the infrarenal abdominal aorta using external vascular clamping. Immunocytochemical staining of injured aortas for fibrinogen and &#946;-catenin demonstrate the exposure of a pro-thrombotic surface and the border of intact endothelium, respectively. The method presented here has the advantages of speed, excellent overall survival rate, and relative technical ease, creating a uniquely practical tool for imposing arterial denudation injury in transgenic mouse models. Using this method, investigators may elucidate the mechanisms of re-endothelialization under normal or pathological conditions.

Understanding the cellular and molecular mechanisms of re-endothelialization following arterial denudation injury is of paramount importance in preventing thrombosis and restenosis of arteries. Here we describe a protocol for reproducible arterial denudation injury of the infrarenal abdominal aorta. The procedure was developed to investigate the underlying mechanisms that regulate endothelial regeneration using mouse models.

Percutaneous vascular interventions uniformly result in arterial denudation injuries that subsequently lead to thrombosis and restenosis. These ...

Full-root Aortic Valve Replacement by Stentless Aortic Xenografts in Patients with Small Aortic Roots

In patients with small aortic roots who need an aortic valve replacement with biological valve substitutes, the implantation of the stented pericardial valve might not meet the functional needs. The implantation of a too-small stented pericardial valve, leading to an effective orifice area indexed to a body surface area less than 0.85 cm2/m2, is regarded as prosthesis-patient mismatch (PPM). A PPM negatively affects the regression of left ventricular hypertrophy and thus the normalization of left ventricular function and the alleviation of symptoms. Persistent left ventricular hypertrophy is associated with an increased risk of arrhythmias and sudden cardiac death. In the case of predictable PPM, there are three options: 1) accept the PPM resulting from the implantation of a stented pericardial valve when comorbidities of the patient forbid the more technically demanding operative technique of implanting a larger prosthesis, 2) enlarge the aortic root to accommodate a larger stented valve substitute, or 3) implant a stentless biological valve or a homograft. Compared to classical aortic valve replacement with stented pericardial valves, the full-root implantation of stentless aortic xenografts offers the possibility of implanting a 3-4 mm larger valve in a given patient, thus allowing significant reduction in transvalvular gradients. However, a number of cardiac surgeons are reluctant to transform a classical aortic valve replacement with stented pericardial valves into the more technically challenging full-root implantation of stentless aortic xenografts. Given the potential hemodynamic advantages of stentless aortic xenografts, we have adopted full-root implantation to avoid PPM in patients with small aortic roots necessitating an aortic valve replacement. Here, we describe in detail a technique for the full-root implantation of stentless aortic xenografts, with emphasis on the management of the proximal suture line and coronary anastomoses. Limitations of this technique and alternative options are discussed.

Full-root aortic valve replacement by stentless aortic xenograft is a viable option in patients with small aortic roots. We describe, a technique for the full-root implantation of stentless aortic xenografts, with emphasis on the management of the proximal suture line and coronary anastomoses, and discuss its limitations and alternative options.

In patients with small aortic roots who need an aortic valve replacement with biological valve substitutes, the implantation of the stented pericardial ...

Technique of Minimally Invasive Transverse Aortic Constriction in Mice for Induction of Left Ventricular Hypertrophy

Transverse aortic constriction (TAC) in mice is one of the most commonly used surgical techniques for experimental investigation of pressure overload-induced left ventricular hypertrophy (LVH) and its progression to heart failure. In the majority of the reported investigations, this procedure is performed with intubation and ventilation of the animal which renders it demanding and time-consuming and adds to the surgical burden to the animal. The aim of this protocol is to describe a simplified technique of minimally invasive TAC without intubation and ventilation of mice. Critical steps of the technique are emphasized in order to achieve low mortality and high efficiency in inducing LVH.
Male C57BL/6 mice (10-week-old, 25-30 g, n=60) were anesthetized with a single intraperitoneal injection of a mixture of ketamine and xylazine. In a spontaneously breathing animal following a 3-4 mm upper partial sternotomy, a segment of 6/0 silk suture threaded through the eye of a ligation aid was passed under the aortic arch and tied over a blunted 27-gauge needle. Sham-operated animals underwent the same surgical preparation but without aortic constriction. The efficacy of the procedure in inducing LVH is attested by a significant increase in the heart/body weight ratio. This ratio is obtained at days 3, 7, 14 and 28 after surgery (n = 6 - 10 in each group and each time point). Using our technique, LVH is observed in TAC compared to sham animals from day 7 through day 28. Operative and late (over 28 days) mortalities are both very low at 1.7%.
In conclusion, our cost-effective technique of minimally invasive TAC in mice carries very low operative and post-operative mortalities and is highly efficient in inducing LVH. It simplifies the operative procedure and reduces the strain put on the animal. It can be easily performed by following the critical steps described in this protocol.

The aim of this protocol is to describe step-by-step the technique of minimally invasive transverse aortic constriction (TAC) in mice. By elimination of intubation and ventilation which are mandatory for the commonly used standard procedure, minimally invasive TAC simplifies the operative procedure and reduces the strain put on the animal.

Transverse aortic constriction (TAC) in mice is one of the most commonly used surgical techniques for experimental investigation of pressure ...

Utilizing Percutaneous Ventricular Assist Devices in Acute Myocardial Infarction Complicated by Cardiogenic Shock

Cardiogenic shock is defined as persistent hypotension, accompanied by evidence of end organ hypo-perfusion. Percutaneous ventricular assist devices (PVADs) are used for the treatment of cardiogenic shock in an effort to improve hemodynamics. Impella is currently the most common PVAD and actively pumps blood from the left ventricle into the aorta. PVADs unload the left ventricle, increase cardiac output and improve coronary perfusion. PVADs are typically placed in the cardiac catheterization laboratory under fluoroscopic guidance via the femoral artery when feasible. In cases of severe peripheral arterial disease, PVADs can be implanted through an alternative access. In this article, we summarize the mechanism of action of PVAD and the data supporting their use in the treatment of cardiogenic shock.

Percutaneous ventricular assist devices are increasingly being utilized in patients with acute myocardial infarction and cardiogenic shock. Herein, we discuss the mechanism of action and hemodynamic effects of such devices. We also review algorithms and best practices for the implantation, management and weaning of these complex devices.

Cardiogenic shock is defined as persistent hypotension, accompanied by evidence of end organ hypo-perfusion. Percutaneous ventricular assist devices ...

Use of a Percutaneous Ventricular Assist Device/Left Atrium to Femoral Artery Bypass System for Cardiogenic Shock

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the left ventricle by draining blood from the left atrium (LA) and returning it to the systemic arterial circulation via the femoral artery. It can provide flows ranging from 2.5-5 L/min depending on the size of the cannula. Here, we discuss the mechanism of action of LAFAB, available clinical data, indications for its use in cardiogenic shock, steps of implantation, post-procedural care, and complications associated with the use of this device and their management.
We also provide a brief video of the procedural component of device therapy, including the pre-placement preparation, percutaneous placement of the device via transseptal puncture under echocardiographic guidance and the post-operative management of device parameters.

The following article describes the stepwise procedure for placement of a device (e.g., Tandemheart) in cardiogenic shock (CS) that is a percutaneous left ventricular assist device (pLVAD) and a left atrial to femoral artery bypass (LAFAB) system that bypasses and supports the left ventricle (LV) in CS.

The left atrial to femoral artery bypass (LAFAB) system is a mechanical circulatory support (MCS) device used in cardiogenic shock (CS) that bypasses the ...

A Model of Reverse Vascular Remodeling in Pulmonary Hypertension Due to Left Heart Disease by Aortic Debanding in Rats

Pulmonary hypertension due to left heart disease (PH-LHD) is the most common form of PH, yet its pathophysiology is poorly characterized than pulmonary arterial hypertension (PAH). As a result, approved therapeutic interventions for the treatment or prevention of PH-LHD are missing. Medications used to treat PH in PAH patients are not recommended for treatment of PH-LHD, as reduced pulmonary vascular resistance (PVR) and increased pulmonary blood flow in the presence of increased left-sided filling pressures may cause left heart decompensation and pulmonary edema. New strategies need to be developed to reverse PH in LHD patients. In contrast to PAH, PH-LHD develops due to increased mechanical load caused by congestion of blood into the lung circulation during left heart failure. Clinically, mechanical unloading of the left ventricle (LV) by aortic valve replacement in aortic stenosis patients or by implantation of LV assist devices in end-stage heart failure patients normalizes not only pulmonary arterial and right ventricular (RV) pressures but also PVR, thus providing indirect evidence for reverse remodeling in the pulmonary vasculature. Using an established rat model of PH-LHD due to left heart failure triggered by pressure overload with subsequent development of PH, a model is developed to study the molecular and cellular mechanisms of this physiological reverse remodeling process. Specifically, an aortic debanding surgery was performed, which resulted in reverse remodeling of the LV myocardium and its unloading. In parallel, complete normalization of RV systolic pressure and significant but incomplete reversal of RV hypertrophy was detectable. This model may present a valuable tool to study the mechanisms of physiological reverse remodeling in the pulmonary circulation and the RV, aiming to develop therapeutic strategies for treating PH-LHD and other forms of PH.

The present protocol describes a surgical procedure to remove ascending-aortic banding in a rat model of pulmonary hypertension due to left heart disease. This technique studies endogenous mechanisms of reverse remodeling in the pulmonary circulation and the right heart, thus informing strategies to reverse pulmonary hypertension and/or right ventricular dysfunction.

Pulmonary hypertension due to left heart disease (PH-LHD) is the most common form of PH, yet its pathophysiology is poorly characterized than pulmonary ...