This work was supported by Charles University research grants GA UK No. 538216 and GA UK No. 1114213.

This experimental protocol was reviewed and approved by the Institutional Animal Expert Committee at First Faculty of Medicine, Charles University, and was performed at the University experimental laboratory, Department of Physiology, First Faculty of Medicine, Charles University in Prague, Czech Republic, in accordance with Act No. 246/1992 Coll., on the protection of animals against cruelty. All animals were treated and cared for in accordance with the Guide for the Care and Use of Laboratory Animals, 8th edition, published by National Academies Press, 2011. All procedures were performed according to standard veterinary conventions and at the completion of each study, the animal was sacrificed and a necropsy performed. Due to suitable anatomy, five healthy crossbred female swine (Sus scrofa domestica) up to 6 months of age were included in this experiment. Their mean body weight was 66 &#177; 20 kg at the day of data collection.
1. General Anesthesia
<ol>
	<li>After 1 day of fasting, initiate anesthesia by intramuscular administration of midazolam (0.3 mg/kg) and ketamine hydrochloride (15 - 20 mg/kg) to the gluteal region.</li>
	<li>Insert peripheral cannula into the marginal ear vein for intravenous drug applications.</li>
	<li>Administer intravenous boluses of propofol (2 mg/kg) and morphine (0.1 - 0.2 mg/kg).</li>
	<li>Provide animals with oxygen via a facial mask and advance orotracheal intubation with a cuffed endotracheal tube with a diameter of 6.5 - 7.5 mm.</li>
	<li>Continue the total intravenous anesthesia by combination of propofol (6 - 12 mg/kg/h), midazolam (0.1 - 0.2 mg/kg/h), and morphine (0.1 - 0.2 mg/kg/h), adjusting the doses according to individual responses - suppress spontaneous breaths, corneal reflexes, and motoric response. Protect the animal&#39;s eyes with ointment to prevent dryness.</li>
	<li>Operate the mechanical ventilation by a closed-loop automatic device set to adaptive support ventilation to maintain target end-tidal CO2 of 38 - 42 mmHg and adequate hemoglobin saturation of 95 - 99%. Monitor all vital functions, especially heart rate and body temperature.</li>
	<li>Attach the animal by securing its legs gently to the operation table in the supine position.</li>
	<li>Administer wide spectrum antibiotics - 1 g of cefazolin intravenously through the ear vein cannula.</li>
</ol>
2. Ventricular Lead Implantation
<ol>
	<li>Locate surgical sites and shave the skin properly using a razor at (1) the jugular region above the sternocleidomastoid muscle and (2) the unilateral paravertebral region on the back side of the animal&#39;s neck.</li>
	<li>Using the ultrasound vascular probe, visualize the external jugular vein and mark its location on the skin. Locate the carotid artery as well to prevent its injury.</li>
	<li>After the wide skin disinfection using povidone iodine, cover with a sterile surgical drape with the hole over the marked jugular region.</li>
	<li>Prepare all necessary tools for pacemaker implantation and keep them sterile. It is crucial to maintain a sterile environment throughout the procedure.</li>
	<li>Cut the skin parallel above the external jugular vein, form a shallow subcutaneous pocket in soft tissue not more than 10 mm deep. Do not expose any large vessels.</li>
	<li>From the bottom of the preformed pocket, insert a sheath into the external jugular vein, using the standard Seldinger technique. First, insert a soft-tip guidewire through a 12G puncture needle, and then over the guidewire introduce a 7-French plastic tear away introducer sheath with a dilator.</li>
	<li>Under fluoroscopic guidance, introduce a 58 cm pacing lead through this sheath and position its tip to the apex of the right ventricle. Then, remove the sheath and fixate the active tip of the electrode to the myocardium by screwing out its helix.</li>
	<li>Test the pacing parameters - the lead sensed signal from ventricular electrocardiogram and impedance must be stable, the pacing threshold should be below an amplitude of 1 V with 0.4 ms of pulse duration.</li>
	<li>Pull a rubber sleeve on the pacing lead and fix both together to the bottom of the preformed jugular subcutaneous pocket by two non-absorbable suture braided thread stitches. Importantly, enough length of the pacing lead must be inserted, considering the future possible growth of the animal.</li>
</ol>
3. Subcutaneous Lead Tunneling
<ol>
	<li>Turn the animal over on its side and disinfect the previously shaved skin region lateral to the backbone, then cover with a sterile surgical drape with a hole. Make sure the jugular subcutaneous pocket and the lead remain sterile.</li>
	<li>Cut the skin lateral to the backbone and form a deep, spacious, subcutaneous pocket. Use dull preparation and stop any possible bleeding.</li>
	<li>Take a soft rubber extension tube from a sterile infusion set and cut off both its ends. Using a tunneling tool, preform a direct subcutaneous tunnel connecting the jugular and dorsal subcutaneous pockets with this extension tube.</li>
	<li>Connect the tube&#39;s free end to the ventricular lead by pulling it onto its IS-1 connector and draw the lead through the preformed tunnel into the dorsal subcutaneous pocket by pulling the tube dorsally. It may be useful to secure the connection with a silk tie.</li>
	<li>Remove both the tunneling tool and the extension tube, exposing the ventricular lead from the dorsal subcutaneous pocket.</li>
</ol>
4. Pacemaker Implantation
<ol>
	<li>Set up the implantable dual-chamber heart pacemaker unit with the &#34;Y&#34; connecting part. The &#34;Y&#34; connection allows a convergent connection of both pacemaker outputs to be joined and connected together to the single pacing lead (Figure 1 and Figure 2). This setting will later provide a wide range of pacing frequencies.</li>
	<li>After connecting the pacing lead, fasten all the IS-1 connection screws in the pacemaker header unit and the &#34;Y&#34; lead connection.</li>
	<li>Hide the whole pacing system in the deep dorsal pocket. There must be enough space to comfortably accommodate the pacemaker unit and any redundant lead.</li>
	<li>Check the final pacing parameters. Make sure that cardiac ventricular pacing is possible from both pacemaker outputs.</li>
	<li>Flush with povidone iodine and close both subcutaneous pockets. Use absorbable braided thread to suture fibrous tissue layers and non-absorbable suture for skin adaptation.</li>
</ol>
5. Postoperative Care
<ol>
	<li>Observe the animal carefully until it regains sufficient consciousness.</li>
	<li>Continue in a wide spectrum intravenous antibiotic regimen until the wounds are healed - cefazolin 1 g every 12 h. Administer analgesics in appropriate dosing, e.g., morphine 0.2 mg/kg every 6 - 12 h for 3 days by subcutaneous injection. If necessary, make dose adjustments to adequately prevent pain.</li>
	<li>Place the animal in a comfortable, calm facility at room temperature. Allow free access to water and suitable alimentation.</li>
	<li>Dress the wounds with sterile scrubs regularly to preserve clean healing.</li>
	<li>To provide rest after the surgical procedure, keep the pacemaker inhibited by native heart rhythm&#160;for at least 3 days.</li>
	<li>Remove the non-absorbable skin sutures when fully healed, approximately 10 - 14 days after the procedure.</li>
</ol>
6. Pacing Protocol
<ol>
	<li>Start the pacing protocol after an adequate resting period. Initially, increase the paced ventricular heart rate to 200 beats/min by setting the dual-chamber pacemaker to mode D00, 100 beats/min, and concomitantly adjusting the AV delay to 300 ms (to exactly match the pace to pace interval, see Table 1). Select the unipolar pacing in both outputs.</li>
	<li>Increase stepwise the paced heart rate to 220 beats/min after 1 week and to 240 beats/min after 2 weeks (Figure 3). Keep continuous pacing at this frequency unless it is not hemodynamically tolerated. If the HF progresses too quickly, reduce the paced heart rate before increasing it again after another week.</li>
	<li>Use auscultation of heart beat, ECG, and pacemaker interrogation daily to verify the heart rate and constant pacing parameters, including battery life.</li>
</ol>
7. Heart Failure Induction and Monitoring
<ol>
	<li>Ensure regular care by a specialized veterinarian and monitor the animal&#39;s general health status. Clinical observations of increasing native heart and respiratory rates, evaluation of peripheral pulse oximetry, and reduction in spontaneous physical activity or appetite provide information about HF progression.</li>
	<li>Use the advantage of wireless transcutaneous pacemaker interrogation and, if possible, continuous ECG recording - frequent non-sustained ventricular tachycardias (VT) are a sign of severe HF progression.</li>
	<li>Use echocardiographic assessments to reveal the structural and functional heart changes. Pay attention to find an optimal image window according to porcine anatomy and heart dilation - for a typical 4 chamber view, place the transducer to the right just below the xiphoid and angle it to point to the neck or left shoulder. For short-axis views, use intercostal windows. Reduction of ventricular ejection fraction in native heart rhythm and atrioventricular regurgitations should be noticeable after a few weeks. 
	NOTE: Significant interindividual differences of high rate ventricular pacing tolerance exist. Therefore, frequent monitoring and individually adapted adjustment of the pacing protocol are necessary.</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57030/57030fig1.jpg" /> 
Figure 1: Heart pacing unit schematic. The dual-chamber pacemaker (1), a &#34;Y&#34; shaped adapter (2) conducting convergently both pacemaker outputs together to a single pacing lead (3). The tip of the lead is fixated into the apical part of the RV cavity (4). This setting provides a wide range of high pacing frequencies. <a href="//cloudfront.jove.com/files/ftp_upload/57030/57030fig1large.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/57030/57030fig2.jpg" /> 
Figure 2: Heart pacing unit. X-ray&#160;(A) and photography (B) of the dual-chamber pacemaker (1), a &#34;Y&#34; shaped adapter (2), and the ventricular pacing lead (3). <a href="//cloudfront.jove.com/files/ftp_upload/57030/57030fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Desired HR</td>
			<td>Set pacemaker rate</td>
			<td>Pace to pace interval</td>
		</tr>
		<tr>
			<td>beats/min</td>
			<td>beats/min</td>
			<td>ms</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>200</td>
			<td>100</td>
			<td>300</td>
		</tr>
		<tr>
			<td>220</td>
			<td>110</td>
			<td>270</td>
		</tr>
		<tr>
			<td>240</td>
			<td>120</td>
			<td>250</td>
		</tr>
		<tr>
			<td>250</td>
			<td>125</td>
			<td>240</td>
		</tr>
	</tbody>
</table>
Table 1: Pacemaker parameters. To allow high rate cardiac pacing with the implanted in-house-modified dual-chamber pacemaker unit, the table shows the desired paced heart rate (HR) and matching pace to pace interval values. The pacemaker must be set to D00 operation mode at a rate of half of the desired HR, and the AV delay set to the corresponding pace to pace interval in milliseconds.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57030/57030fig3.jpg" /> 
Figure 3: Pacing protocol. The progressive phase of the TIC induction starts after a resting period of 3 days. Then, the pacemaker is set to D00 mode with a pacing frequency of 50% of the desired paced frequency, and AV delay is set to the matching pace to pace interval (see Table 1). Thanks to the &#34;Y&#34; shaped adapter, both pacemaker outputs are conducted to a single pacing lead. bpm = beats/minute. <a href="//cloudfront.jove.com/files/ftp_upload/57030/57030fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

The authors have nothing to disclose.

Chronic HF is a major health problem that contributes greatly to morbidity and mortality. The pathogenesis and progression of HF in humans is complex, so an appropriate animal model is critical to investigate the underlying mechanisms and to test novel therapeutics that aim to interfere with native severe disease progression. To study its pathogenesis, large animal models are being used for experimental testing.
In general, surgical models of chronic HF closely mimic this disease. When compare...

The variety of new treatment methods for heart failure (HF), especially the growing worldwide use of mechanical circulatory supports and extracorporeal membrane oxygenation (ECMO) in clinical practice, is reflecting in preclinical experimental testing. The main focus has been on hemodynamic changes caused by the examined treatment modalities, namely on systemic blood pressure1, myocardial contractility, pressure and volume changes in heart chambers and heart work2,3, arterial blood flow in systemic and peripheral arteries, along with metabolic compensation4 - regional tissue saturation, pulmonary perfusion, and blood gas analysis. Other studies are directed on long-term effects of the circulatory support5, concomitant inflammation, or occurrence of hemolysis. All these types of study need a stable biomodel of congestive HF.
Most of the published experiments on left ventricular (LV) performance and hemodynamics of mechanical circulatory support have been performed on experimental models of acute HF2,6,7,8,9,10, or even on completely intact hearts. On the other hand, in clinical practice, mechanical circulatory supports are often being applied in a status of circulatory decompensation that develops on the grounds of previously present chronic heart disease. In such situations, the adaptation mechanisms are fully developed and can play important roles in inconsistency of outcomes observed according to the &#34;acuteness or chronicity&#34; of underlying cardiac disease11. Therefore, a stable model of chronic HF can offer new insights into pathophysiological mechanisms and hemodynamics. Although there are reasons why the use of chronic HF models is scarce - time consuming preparation, instability of heart rhythm, ethical questions, and mortality rate - their advantages are clear, as they offer presence of long-term neurohumoral activation, general systemic adaptation, functional changes of cardiomyocytes, and structural alterations of heart muscle and valves12,13.
In general, the availability and variety of animal models used for hemodynamic studies is wide and offers choice for many specific needs. For these experiments, mostly porcine, canine, ovine, or with smaller settings murine models, are being chosen and offer a good simulation of expected human bodily reactions14. Furthermore, forms of single organ experiments are becoming more frequent15. To reliably mimic the pathophysiology of HF, circulation is being artificially deteriorated. Damage to the heart can be caused by various methods, often by either ischemia, arrhythmia, pressure overload, or cardiotoxic effects of drugs, with any of these leading to hemodynamic deterioration of the model. To produce a true model of chronic HF, time has to be provided for developing the long-term adaptation of the whole organism. Such a reliable and stable model is represented well by tachycardia-induced cardiomyopathy (TIC), which can be produced by rapid cardiac pacing in experimental animals.
It has been shown that in predisposed hearts, long-lasting incessant tachyarrhythmias can lead to systolic dysfunction and dilation with decreased cardiac output. The condition referred to as TIC was first described in 191316, widely used in experiments since 196217, and is now a well-recognized disorder. Its origin can lie in various types of arrhythmias - both supraventricular and ventricular tachycardia can lead to progressive deterioration of systolic function, biventricular dilation, and progressive clinical signs of HF including ascites, edemas, lethargy, and ultimately cardiac decompensation leading to terminal HF and, if not treated, death.
Similar effects of circulatory suppression were observed by introduction of high rate cardiac pacing in animal models. In a porcine model, an atrial or ventricular heart rate over 200 beats/minute is potent enough to induce end-stage HF in a period of 3 - 5 weeks (progressive phase) with characteristics of TIC, though interindividual differences do exist18,19. These findings correspond well to decompensated cardiomyopathy and are, importantly, preserved also after the cessation of pacing (chronic phase)19,20,21,22,23.
Porcine, canine, or ovine TIC models were repeatedly prepared to study the pathophysiology of HF14, as changes to the LV mimic the characteristics of dilated cardiomyopathy24. The hemodynamic characteristics are well described - increased ventricular end-diastolic pressures, decreased cardiac output, increased systemic vascular resistance, and dilation of both ventricles. In contrast, wall hypertrophy is not observed consistently, and even wall thinning was described by some researchers25,26. With progression of ventricular dimensions, regurgitation on atrioventricular valves develops26.
In this publication, we present a protocol to produce a TIC by long-term fast cardiac pacing in swine. This biomodel represents potent means to study decompensated dilated cardiomyopathy, hemodynamics of progressive chronic HF with low cardiac output, and effects of applied treatment.

<table border="0" cellpadding="0" cellspacing="0" width="848">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:271px;">Medication</td>
			<td style="width:176px;"></td>
			<td style="width:119px;"></td>
			<td style="width:283px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">midazolam</td>
			<td>Roche</td>
			<td>Dormicum</td>
			<td>anesthetic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ketamine hydrochloride</td>
			<td>Richter Gedeon</td>
			<td>Calypsol</td>
			<td>anesthetic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">propofol</td>
			<td>B.Braun</td>
			<td>Propofol</td>
			<td>anesthetic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">cefazolin</td>
			<td>Medochemie</td>
			<td>Azepo</td>
			<td>antibiotic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Silver Aluminium Aerosol</td>
			<td>Henry Schein</td>
			<td>9003273</td>
			<td>tincture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">povidone iodine</td>
			<td>Egis Praha</td>
			<td>Betadine</td>
			<td>disinfection</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">morphine</td>
			<td>Biotika Bohemia</td>
			<td>Morphin 1% inj</td>
			<td>analgetic</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tools</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td colspan="3" height="21" style="height:21px;">Metzenbaum scissors, lancet with #22 blade, DeBakey forceps, needle driver</td>
			<td>basic surgical equipment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">cauterizer</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-0 Vicryl</td>
			<td>Ethicon</td>
			<td>V323H</td>
			<td>absorbable braided suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-0 Perma-Hand Silk</td>
			<td>Ethicon</td>
			<td>A185H</td>
			<td>silk tie suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">2-0 Prolene</td>
			<td>Ethicon</td>
			<td>8433H</td>
			<td>non-absorbable suture</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Diagnostic devices</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ESP C-arm</td>
			<td>GE Healthcare</td>
			<td>ESP</td>
			<td>X-ray fluoro C-arm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acuson x300</td>
			<td>Siemens Healthcare</td>
			<td></td>
			<td>ultrasound system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acuson P5-1</td>
			<td>Siemens Healthcare</td>
			<td></td>
			<td>echocardiographic probe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acuson VF10-5</td>
			<td>Siemens Healthcare</td>
			<td></td>
			<td>sonographic vascular probe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">3PSB, 4PSB and 6PSB</td>
			<td>Transonic Systems</td>
			<td></td>
			<td>perivascular flow probes</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TS420</td>
			<td>Transonic Systems</td>
			<td></td>
			<td>perivascular flow module</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TruWave&#160;</td>
			<td>Edwards Lifesciences</td>
			<td>T001660A</td>
			<td>fluid-filled pressure transducer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">7.0F VSL Pigtail</td>
			<td>Transonic Systems</td>
			<td></td>
			<td>pressure sensor catheter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">INVOS 5100C Cerebral/Somatic Oximeter</td>
			<td>Somanetics/Medtronic</td>
			<td></td>
			<td>near infrared spectroscopy</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CCO Combo Catheter</td>
			<td>Edwards Lifesciences</td>
			<td>744F75</td>
			<td>Swan-Ganz pulmonary artery catheter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vigillace II</td>
			<td>Edwards Lifesciences</td>
			<td>VIG2E</td>
			<td>cardiac output monitor</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">7.0F VSL Pigtail</td>
			<td>Transonic Systems</td>
			<td></td>
			<td>pressure-volume catheter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ADV500</td>
			<td>Transonic Systems</td>
			<td></td>
			<td>pressure-volume system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LabChart and PowerLab</td>
			<td>ADInstruments</td>
			<td></td>
			<td>data acquisition and analysis system</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Prism 6</td>
			<td>GraphPad</td>
			<td></td>
			<td>statistical analysis software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pacing devices</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ICS 3000</td>
			<td>Biotronic</td>
			<td>349528</td>
			<td>pacemaker programmer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ERA 3000</td>
			<td>Biotronic</td>
			<td>128828</td>
			<td>external pacemaker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Effecta DR</td>
			<td>Biotronic</td>
			<td>371199</td>
			<td>dual-chamber pacemaker</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tendril STS</td>
			<td>St. Jude Medical</td>
			<td>2088TC/58</td>
			<td>ventricular pacing lead</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lead permanent adapter</td>
			<td>Osypka</td>
			<td>Article 53422</td>
			<td>convergent &#34;Y&#34; connecting part</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lead permanent adapter</td>
			<td>Osypka</td>
			<td>Article 53904</td>
			<td>convergent &#34;Y&#34; connecting part</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tear-Away Introducer 7F</td>
			<td>B.Braun</td>
			<td>5210593</td>
			<td>tear away introducer sheath&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Split Cath Tunneler</td>
			<td>medComp</td>
			<td>AST-L</td>
			<td>tunneling tool</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">infusion line</td>
			<td>MPH Medical Devices</td>
			<td>2200045</td>
			<td>connecting line</td>
		</tr>
	</tbody>
</table>

tachycardia-induced cardiomyopathy as a chronic heart failure model in swine

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment methods. Here, we present such a model by tachycardia-induced cardiomyopathy, which can be produced by rapid cardiac pacing in swine.
A single pacing lead is introduced transvenously into fully anaesthetized healthy swine, to the apex of the right ventricle, and fixated. Its other end is then tunneled dorsally to the paravertebral region. There, it is connected to an in-house modified heart pacemaker unit that is then implanted in a subcutaneous pocket. 
After 4 - 8 weeks of rapid ventricular pacing at rates of 200 - 240 beats/min, physical examination revealed signs of severe heart failure - tachypnea, spontaneous sinus tachycardia, and fatigue. Echocardiography and X-ray showed dilation of all heart chambers, effusions, and severe systolic dysfunction. These findings correspond well to decompensated dilated cardiomyopathy and are also preserved after the cessation of pacing.
This model of tachycardia-induced cardiomyopathy can be used for studying the pathophysiology of progressive chronic heart failure, especially hemodynamic changes caused by new treatment modalities like mechanical circulatory supports. This methodology is easy to perform and the results are robust and reproducible.

Testing the model: After signs of decompensated chronic HF became prominent, anesthesia and artificial ventilation were administered again following the principles described above, but dosing was adjusted due to low cardiac output27. Due to possible cardiodepressive effects of anesthetics, careful intensive monitoring of vital functions is necessary.
The animal was attached in the supine ...

Watch this Scientific Journal Video about Tachycardia-Induced Cardiomyopathy As a Chronic Heart Failure Model in Swine at JoVE.com

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

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

A stable and reliable model of chronic heart failure is required for many experiments to understand hemodynamics or to test effects of new treatment ...

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13.4K Views.  Charles University. Here, we present a protocol to produce tachycardia-induced cardiomyopathy in swine. This model represents a potent way to study the hemodynamics of progressive chronic heart failure and the effects of applied treatment.

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

Gene Transfer for Ischemic Heart Failure in a Preclinical Model

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine their efficacy and safety.
Gene therapy using viral vectors is one of the most promising approaches for treating cardiac diseases. Viral delivery of various different genes by changing the carrier gene has immeasurable therapeutic potential.
In this video, the full process of an animal model of heart failure creation followed by gene transfer is presented using a swine model. First, myocardial infarction is created by occluding the proximal left anterior descending coronary artery. Heart remodeling results in chronic heart failure. Unique to our model is a fairly large scar which truly reflects patients with severe heart failure who require aggressive therapy for positive outcomes. After myocardial infarct creation and development of scar tissue, an intracoronary injection of virus is demonstrated with simultaneous nitroglycerine infusion. Our injection method provides simple and efficient gene transfer with enhanced gene expression. This combination of a myocardial infarct swine model with intracoronary virus delivery has proven to be a consistent and reproducible methodology, which helps not only to test the effect of individual gene, but also compare the efficacy of many genes as therapeutic candidates.

A method of gene transfer for the treatment of ischemic heart failure is described using a swine model of myocardial infarction. Our simple and reproducible method enables us to readily evaluate the efficacy of various gene transfers with a very simple and reproducible way.

Various emerging technologies are being developed for patients with heart failure. Well-established preclinical evaluations are necessary to determine ...

A Swine Model of Neonatal Asphyxia

Annually more than 1 million neonates die worldwide as related to asphyxia. Asphyxiated neonates commonly have multi-organ failure including hypotension, perfusion deficit, hypoxic-ischemic encephalopathy, pulmonary hypertension, vasculopathic enterocolitis, renal failure and thrombo-embolic complications. Animal models are developed to help us understand the patho-physiology and pharmacology of neonatal asphyxia. In comparison to rodents and newborn lambs, the newborn piglet has been proven to be a valuable model. The newborn piglet has several advantages including similar development as that of 36-38 weeks human fetus with comparable body systems, large body size (&tilde;1.5-2 kg at birth) that allows the instrumentation and monitoring of the animal and controls the confounding variables of hypoxia and hemodynamic derangements.
We here describe an experimental protocol to simulate neonatal asphyxia and allow us to examine the systemic and regional hemodynamic changes during the asphyxiating and reoxygenation process as well as the respective effects of interventions. Further, the model has the advantage of studying multi-organ failure or dysfunction simultaneously and the interaction with various body systems. The experimental model is a non-survival procedure that involves the surgical instrumentation of newborn piglets (1-3 day-old and 1.5-2.5 kg weight, mixed breed) to allow the establishment of mechanical ventilation, vascular (arterial and central venous) access and the placement of catheters and flow probes (Transonic Inc.) for the continuously monitoring of intra-vascular pressure and blood flow across different arteries including main pulmonary, common carotid, superior mesenteric and left renal arteries. Using these surgically instrumented piglets, after stabilization for 30-60 minutes as defined by Z&lt;10% variation in hemodynamic parameters and normal blood gases, we commence an experimental protocol of severe hypoxemia which is induced via normocapnic alveolar hypoxia. The piglet is ventilated with 10-15% oxygen by increasing the inhaled concentration of nitrogen gas for 2h, aiming for arterial oxygen saturations of 30-40%. This degree of hypoxemia will produce clinical asphyxia with severe metabolic acidosis, systemic hypotension and cardiogenic shock with hypoperfusion to vital organs. The hypoxia is followed by reoxygenation with 100% oxygen for 0.5h and then 21% oxygen for 3.5h. Pharmacologic interventions can be introduced in due course and their effects investigated in a blinded, block-randomized fashion.

Large animal models have good translational values in the examination of physiology and pharmacology of neonatal asphyxia. Using newborn piglets, we develop an experimental protocol to simulate neonatal asphyxia which has advantages of studying the systemic and regional hemodynamics, oxygen transport with biochemical and pathologic pathways and correlations.

Annually more than 1 million neonates die worldwide as related to asphyxia. Asphyxiated neonates commonly have multi-organ failure including hypotension, ...

Urinary Bladder Distention Evoked Visceromotor Responses as a Model for Bladder Pain in Mice

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized by increased urgency and frequency of urination, as well as nocturia and general pelvic pain, especially upon bladder filling or voiding. Despite years of research, the cause of IC/BPS remains elusive and treatment strategies are unable to provide complete relief to patients. In order to study nervous system contributions to the condition, many animal models have been developed to mimic the pain and symptoms associated with IC/BPS. One such murine model is urinary bladder distension (UBD). In this model, compressed air of a specific pressure is delivered to the bladder of a lightly anesthetized animal over a set period of time. Throughout the procedure, wires in the superior oblique abdominal muscles record electrical activity from the muscle. This activity is known as the visceromotor response (VMR) and is a reliable and reproducible measure of nociception. Here, we describe the steps necessary to perform this technique in mice including surgical manipulations, physiological recording, and data analysis. With the use of this model, the coordination between primary sensory neurons, spinal cord secondary afferents, and higher central nervous system areas involved in bladder pain can be unraveled. This basic science knowledge can then be clinically translated to treat patients suffering from IC/BPS.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition characterized in part by pelvic pain. In order to study nervous system contributions to the condition, a physiological model of urinary bladder pain is used in mice and rats.

Approximately 3-8 million people in the United States suffer from interstitial cystitis/bladder pain syndrome (IC/BPS), a debilitating condition ...

A Chronic Cardiac Ischemia Model in Swine Using an Ameroid Constrictor

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but regardless of the approach, an in vivo model is needed to test each treatment. The pig is one of the most used large animal models for cardiovascular disease. Its heart is very similar in anatomy and function to that of a human. The ameroid placement technique creates an ischemic area of the heart, which has many useful applications in studying myocardial infarction. This model has been used for surgical research, pharmaceutical studies, imaging techniques, and cell therapies.
There are several ways of inducing an ischemic area in the heart. Each has its advantages and disadvantages, but the placement of an ameroid constrictor remains the most widely used technique. The main advantages to using the ameroid are its prevalence in existing research, its availability in various sizes to accommodate the anatomy and size of the vessel to be constricted, the surgery is a relatively simple procedure, and the post-operative monitoring is minimal, since there are no external devices to maintain. This paper provides a detailed overview of the proper technique for the placement of the ameroid constrictor.

The purpose of this protocol is to demonstrate the placement of a delayed constricting device (an ameroid constrictor) around a coronary artery in a swine model. This device creates an ischemic area of the heart that is useful for studying new diagnostic imaging techniques and new methods of treatment.

Cardiovascular disease remains the number one cause of mortality in the United States. There are numerous approaches to treating these diseases, but ...

A Doxorubicin-induced Cardiomyopathy Model in Adult Zebrafish

The genetically accessible adult zebrafish (Danio rerio) has been increasingly used as a vertebrate model for understanding human diseases such as cardiomyopathy. Because of its convenience and amenability to high throughput genetic manipulations, the generation of acquired cardiomyopathy models, such as the doxorubicin-induced cardiomyopathy (DIC) model in adult zebrafish, is opening the doors to new research avenues, including discovering cardiomyopathy modifiers via forward genetic screening. Different from the embryonic zebrafish DIC model, both initial acute and later chronic phases of cardiomyopathy can be determined in the adult zebrafish DIC model, enabling the study of stage-dependent signaling mechanisms and therapeutic strategies. However, variable results can be obtained with the current model, even in the hands of experienced investigators. To facilitate future implementation of the DIC model, we present a detailed protocol on how to generate this DIC model in adult zebrafish and describe two alternative ways of intraperitoneal (IP) injection. We further discuss options on how to reduce variations to obtain reliable results and provide suggestions on how to appropriately interpret the results.

A method to generate a doxorubicin-induced cardiomyopathy model in adult zebrafish (Danio rerio) is described here. Two alternative ways of intraperitoneal injection are presented and conditions to reduce variations among different experimental groups are discussed.

The genetically accessible adult zebrafish (Danio rerio) has been increasingly used as a vertebrate model for understanding human diseases such as ...

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 ...

Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major causes of mortality and morbidity around the world. Cell-based therapies for cardiac repair and improvement of left ventricular function after MI have attracted considerable attention. Accordingly, the safety and efficacy of these cell transplantations should be tested in a preclinical large animal model of HF prior to clinical use. Pigs are widely used for cardiovascular disease research due to their similarity to humans in terms of heart size and coronary anatomy. Therefore, we sought to present an effective protocol for the establishment of a porcine chronic HF model using closed-chest coronary balloon occlusion of the left circumflex artery (LCX), followed by rapid ventricular pacing induced with pacemaker implantation. Eight weeks later, the stem cells were administered by intramyocardial injection in the peri-infarct area. Then the infarct size, cell survival, and left ventricular function (including echocardiography, hemodynamic parameters, and electrophysiology) were evaluated. This study helps establish a stable preclinical large animal HF model for stem cell treatment.

We sought to establish a swine model of heart failure induced by left circumflex artery blockage and rapid pacing to test the effect and safety of intramyocardial administration of stem cells for cell-based therapies.

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major ...

A Rat Model of Pressure Overload Induced Moderate Remodeling and Systolic Dysfunction as Opposed to Overt Systolic Heart Failure

In response to an injury, such as myocardial infarction, prolonged hypertension or a cardiotoxic agent, the heart initially adapts through the activation of signal transduction pathways, to counteract, in the short-term, for the cardiac myocyte loss and or the increase in wall stress. However, prolonged activation of these pathways becomes detrimental leading to the initiation and propagation of cardiac remodeling leading to changes in left ventricular geometry and increases in left ventricular volumes; a phenotype seen in patients with systolic heart failure (HF). Here, we describe the creation of a rat model of pressure overload induced moderate remodeling and early systolic dysfunction (MOD) by ascending aortic banding (AAB) via a vascular clip with an internal area of 2 mm2. The surgery is performed in 200 g Sprague-Dawley rats. The MOD HF phenotype develops at 8-12 weeks after AAB and is characterized noninvasively by means of echocardiography. Previous work suggests the activation of signal transduction pathways and altered gene expression and post-translational modification of proteins in the MOD HF phenotype that mimic those seen in human systolic HF; therefore, making the MOD HF phenotype a suitable model for translational research to identify and test potential therapeutic anti-remodeling targets in HF. The advantages of the MOD HF phenotype compared to the overt systolic HF phenotype is that it allows for the identification of molecular targets involved in the early remodeling process and the early application of therapeutic interventions. The limitation of the MOD HF phenotype is that it may not mimic the spectrum of diseases leading to systolic HF in human. Moreover, it is a challenging phenotype to create, as the AAB surgery is associated with high mortality and failure rates with only 20% of operated rats developing the desired HF phenotype.

We describe the creation of a rat model of pressure overload induced moderate remodeling and early systolic dysfunction where signal transduction pathways involved in the initiation of the remodeling process are activated. This animal model will aid in identifying molecular targets for applying early therapeutic anti-remodeling strategies for heart failure.

In response to an injury, such as myocardial infarction, prolonged hypertension or a cardiotoxic agent, the heart initially adapts through the activation ...

A Doxorubicin-Induced Murine Model of Dilated Cardiomyopathy In Vivo

Dilated cardiomyopathy (DCM) refers to a spectrum of heterogeneous myocardial disorders characterized by ventricular dilation and depressed cardiac performance in the absence of hypertension, valvular, congenital, or ischemic heart diseases, and which may be related to infection, autoimmune or metabolic abnormalities, or family inheritance. It can progress into congestive heart failure with a poor prognosis. Doxorubicin (Dox) is widely employed as a chemotherapeutic drug, but its use is limited because it causes DCM-like changes of the myocardium. Its myocardial toxicity is attributed to oxidative stress, chronic inflammation, and cardiomyocyte apoptosis. A model of DCM exploiting these Dox-induced DCM symptoms has not been established.

Described is a protocol to establish a Doxorubicin-induced dilated cardiomyopathy (DCM) model in mice via long-term intraperitoneal injection of Doxorubicin.

Dilated cardiomyopathy (DCM) refers to a spectrum of heterogeneous myocardial disorders characterized by ventricular dilation and depressed cardiac ...

Myocardial Infarction by Percutaneous Embolization Coil Deployment in a Swine Model

Myocardial infarction (MI) is the leading cause of mortality worldwide. Despite the use of evidence-based treatments, including coronary revascularization and cardiovascular drugs, a significant proportion of patients develop pathological left-ventricular remodeling and progressive heart failure following MI. Therefore, new therapeutic options, such as cellular and gene therapies, among others, have been developed to repair and regenerate injured myocardium. In this context, animal models of MI are crucial in exploring the safety and efficacy of these experimental therapies before clinical translation. Large animal models such as swine are preferred over smaller ones due to the high similarity of swine and human hearts in terms of coronary artery anatomy, cardiac kinetics, and the post-MI healing process. Here, we aimed to describe an MI model in pig by permanent coil deployment. Briefly, it comprises a percutaneous selective coronary artery cannulation through retrograde femoral access. Following coronary angiography, the coil is deployed at the target branch under fluoroscopic guidance. Finally, complete occlusion is confirmed by repeated coronary angiography. This approach is feasible, highly reproducible, and emulates the pathogenesis of human non-revascularized MI, avoiding the traditional open-chest surgery and the subsequent postoperative inflammation. Depending on the time of follow-up, the technique is suitable for acute, sub-acute, or chronic MI models.

Myocardial infarction (MI) animal models that emulate the natural process of the disease in humans are crucial to understanding pathophysiological mechanisms and testing the safety and efficacy of new emergent therapies. Here, we describe an MI swine model created by deploying a percutaneous embolization coil.

Myocardial infarction (MI) is the leading cause of mortality worldwide. Despite the use of evidence-based treatments, including coronary revascularization ...