Name: cox-maze iv procedure concomitant with valvular surgery in situs inversus dextrocardia: a single-center experience in china
Uploaded: 2022-02-11T14:45:00.000+00:00
Duration: 8 min 42 s
Description: Watch this Scientific Journal Video about Cox-Maze IV Procedure Concomitant with Valvular Surgery In Situs Inversus Dextrocardia: A Single-Center Experience in China at JoVE.com

We thank the patients for participating in this study. We are also grateful to the Biomedicine Electron Microscopy Laboratory of Basic Medical Science School of Central South University, particularly to Xiaoying Wu and Jin Li for technical support. This work was supported by the National Key Research and Development Program (No. 2018YFC1311204).

The Institutional Review Board approved the study protocol, and samples of the dilated left atrium (LA) tissues in the dextrocardia cases were collected for electron microscopy after written informed consent had been obtained.
1. Surgical procedure and ablation
<ol>
	<li>Perform a median sternotomy and suspend the left lateral pericardium after opening.
	<ol>
		<li>Cannulate the ascending aorta and the superior and inferior vena cava (SVC, IVC) to establish mild hypothermic cardiopulmonary bypass (CPB).</li>
		<li>Have the operator switch position from the right side to the left of the operating table after establishing the bypass.</li>
		<li>Give antegrade cold blood cardioplegia intermittently from the aortic root to achieve cardioplegic arrest.</li>
		<li>Perform the right atrial (RA) incision on the left side of the heart, parallel to the atrioventricular sulcus, providing exposure for subsequent RA ablation and tricuspid valve surgery. Ensure the left-sided left atriotomy is located parallelly under the interatrial groove.</li>
		<li>Place a retractor on the wall of LA for sufficient exposure to perform LA ablation and approach the mitral valve (MV).</li>
		<li>Make an aortic incision via a transverse aortotomy performed specially for selective antegrade cardioplegia into the left and right coronary orifices and subsequent AV surgery. 
		NOTE: This was done for the second patient.</li>
	</ol>
	</li>
	<li>Cryoablation 
	NOTE: In the previous two patients, cryoablation was performed exclusively using a flexible, 10 cm long, metal cryoprobe (see the Table of Materials). The cryoprobe uses nitrous oxide (N2O) gas to achieve rapid atrial tissue freezing to a target of -60 &#176;C10.
	<ol>
		<li>Design the cryolesion set to replicate the mirror image of the CMP-IV lesion set. Set the duration of the LA cryoablation for each lesion at -60 &#176;C for 2 min.
		<ol>
			<li>Ensure the posterior LA box lesion is composed of the LA incision and the cryolesion encircling the left and right pulmonary veins.</li>
			<li>Apply a cryolesion line to connect the left superior pulmonary vein with the left atrial appendage (LAA).</li>
			<li>Form an ice ball to mark the coronary sinus using cryoablation from the epicardium (Figure 2). When performing the mitral isthmus line, place the cryoprobe at the inferior aspect of the left atriotomy and direct it to the mitral annulus at the 8 o&#39;clock position, across the posterior LA and coronary sinus, as marked with the ice ball (Figure 3A).</li>
			<li>Apply right-sided LAA amputation.</li>
			<li>After the LA cryoablation, sample 4 x 8 mm tissue of the cryoablated LA for electron microscopic examination. In addition, sample a similar, large, nonablated tissue from the margin of the LA incision for the control test. 
			NOTE: Nonablated tissue was sampled in the second case.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform prosthetic valve replacement surgery with a 27 mm mechanical MV using a 2-0 polypropylene running suture. Replace a 23 mm mechanical AV with 2-0 polypropylene running sutures. 
	NOTE: The mechanical MV replacement surgery was performed on the first patient, whereas the replacement with the mechanical AV was done for the second patient.</li>
	<li>Perform the RA cryoablation during the CPB, with the heart warm and beating, for 2 min at -60 &#176;C for each ablation lesion.
	<ol>
		<li>Create the linear cryoablation lines from the inferior aspect of the left-sided right atriotomy up onto the SVC and down to the IVC (Figure 3B).</li>
		<li>Make the tricuspid isthmus linear cryolesion from the midportion of the right atriotomy, directed endocardially toward the tricuspid annulus at the 10 o&#39;clock position (Figure 3B and Figure 4).</li>
		<li>Make a lateral cryolesion from the midportion of the right atriotomy up to the tip of the right atrial appendage (RAA).</li>
	</ol>
	</li>
	<li>Perform three-dimensional (3D) printing of the heart in advance, using the derived cardiac CT data (Figure 5)11. 
	NOTE: This was done for the third patient.
	<ol>
		<li>Access the left atrium through the interatrial groove during the operation. Extend the mitral isthmus lesion to the posterior mitral annulus for the left atrial lesion sets and ablate the coronary sinus in the endocardium and epicardium with a bipolar radiofrequency pen.
		<ol>
			<li>Make other lesions using bipolar radiofrequency clamps: (i) bilateral pulmonary vein isolation; (ii) ablation lines connecting the left atrial appendage and the left superior pulmonary vein; (iii) ablation lines connecting the right and the left superior pulmonary veins; (iv) ablation lines connecting the right and the left inferior pulmonary veins, and (v) mitral line lesions (Figure 3A).</li>
			<li>Dissect the Marshall ligament, and separate the left atrial appendage using an epicardial atrial clamp closure device. Use bipolar radiofrequency forceps to ablate the entire right atrial lesion sets, including the annular tricuspid valve lesions, superior and inferior vena cava lesion lines, and lesion lines connecting the right atrium incision to the right atrial appendage (Figure 3B).</li>
		</ol>
		</li>
		<li>Resect the A1 ruptured chordae, implant a single, flexible, artificial chord with 4-0 expanded polytetrafluoroethylene in situ (see the Table of Materials), and close the residual leak of the anterior commissure and the A2 leaflet cleft.
		<ol>
			<li>Implant a 32 mm, rigid mitral ring to stabilize the annulus. Ensure that the coaptation height is 9 mm after the mitral valve reconstruction. After de-airing and closure of the interatrial sulcus incision, remove the aortic clamp, then make a longitudinal incision on the surface of the right atrium.</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Perform the tricuspid annuloplasty with a 30 mm tricuspid ring or with a 28 mm band, implanting them in an &#34;upside-down&#34; and particularly &#34;mirror-image inversion&#34; manner using 2-0 polyester interrupted sutures (Figure 6). Remove the holder before fixation of the annuloplasty ring. 
	NOTE: Tricuspid annuloplasty was performed in the previous two patients, while the band was used in the third case.</li>
	<li>Ensure that sinus rhythm is restored in all patients without any atrioventricular block before cardiopulmonary bypass weaning. Fix temporary epicardial pacing wires after the cardiac surgery.</li>
</ol>
2. Postoperative management and follow-up
<ol>
	<li>Monitor all patients by continuous ECG recordings during hospitalization to ensure no early AF recurrence occurs.</li>
	<li>Administer antiarrhythmic drugs (AADs) orally, with 200 mg/day of amiodarone routinely, for the first 3-6 months to prevent recurrence of AF.</li>
	<li>Administer warfarin for oral anticoagulation and test prothrombin time (PT) regularly.</li>
	<li>Perform chest roentgenogram, TTE, ECG, and 24 h Holter before discharge.</li>
	<li>After hospital discharge, follow all patients with clinical examination, PT test, TTE, ECG, and 24 h Holter at 3, 6, 12, 18, 24, 36, and 48 months after surgery. 
	NOTE: The third patient was followed during a 12-month follow-up period.</li>
</ol>

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A., Guler, A., Kaya, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitral+valve+replacement+in+a+patient+with+situs+inversus+and+dextrocardia.">Mitral valve replacement in a patient with situs inversus and dextrocardia.</a> The Thoracic and Cardiovascular Surgeon. 59 (5), 305-306 (2011).</li><li>Uchimuro, T., Fukui, T., Matsuyama, S., Tabata, M., Takanashi, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitral+valve+replacement+in+dextrocardia+and+situs+inversus.">Mitral valve replacement in dextrocardia and situs inversus.</a> Kyobu Geka. 65 (10), 858-861 (2012).</li><li>Atsumi, Y., Tokunaga, S., Yasuda, S., Fushimi, K., Masuda, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mitral+valve+surgery+in+a+patient+with+dextrocardia+and+180+degrees+counter-clockwise+rotated+heart+due+to+congenital+agenesis+of+the+right+lung.">Mitral valve surgery in a patient with dextrocardia and 180 degrees counter-clockwise rotated heart due to congenital agenesis of the right lung.</a> Journal of Cardiac Surgery. 28 (6), 635-637 (2013).</li><li>Kikon, M., Kazmi, A., Gupta, A., Grover, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Left-sided+approach+for+mitral+valve+replacement+in+a+case+of+dextrocardia+with+situs+solitus.">Left-sided approach for mitral valve replacement in a case of dextrocardia with situs solitus.</a> Interactive Cardiovascular and Thoracic Surgery. 17 (5), 900-902 (2013).</li><li>Khan, J. 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The authors have no conflicts of interest to disclose.

Dextrocardia is a group of rare heart defects in which the heart is situated on the right side of the thoracic cavity instead of on the left side. One-third of all dextrocardia cases are mirror-image cases, which means the orientation of the cardiac chambers is a mirror image to levocardia (normally situated heart)12. It is estimated that situs inversus dextrocardia associated with situs inversus totalis occurs with an incidence of much less than 1 in 10,000-50,000 births1,2. Exposing and reaching the intracardiac structures was difficult for the three patients in this study presenting with situs inversus dextrocardia and situs inversus. The malposition made it impossible to perform the classic atriotomy incision on the right. Hence, the best method for intracardiac surgery was via the left-sided atriotomy by an operator standing on the left, which is opposite to the normal situation.
AF is the most common cardiac arrhythmia related to systemic or pulmonary thromboembolism and is associated with substantial morbidity and mortality3. The CMP has proven to be the most effective therapeutic method in SR restoration and maintenance13,14. Over a decade of evolution, the modern conception of the Maze procedure was redefined by Damiano, with the new, facilitated iteration termed as the Cox-Maze IV procedure (CMP-IV)15. A prospective study conducted over a decade demonstrated that the CMP-IV gave excellent results and can achieve high success rates in the therapy of AF, with 90-93% freedom from AF and 82-84% freedom from AF off AADs16. The CMP-IV is considered the gold standard for the surgical therapy of AF17. The Society of Thoracic Surgeons 2017 Clinical Practice Guidelines for the surgical treatment of AF recommend CMP-IV with radiofrequency (RF) and cryothermal energy at the time of concomitant cardiac valvular operations to restore SR18. The optimal scheme of ablative energy sources applied for CMP-IV is either cryothermia alone or combined bipolar RF and cryothermia18,19,20.
Cryoablation can be used adjacent to coronary arteries and valve tissue without causing injury, maintaining the structural integrity of the atrial tissue and leaving a smooth endocardial surface21. Moreover, cryoablation allows for the completion of full LA lesion sets via only a left atriotomy, which simplifies the operating steps compared with bipolar RF ablation. Along with its safety and the above features that help replace bipolar RF with cryoablation, cryoablation facilitates establishing the biatrial lesion set of CMP-IV22,23,24. A recent study by Ad and colleagues demonstrated that cryo-CMP achieved a high success rate with 93% SR restoration and 85% SR off-AADs at 2 years after surgery25.
In 2013, our cardiovascular surgery center introduced cryo-CMP-IV in China and has accumulated the largest series of 161 cases to date. Liu and colleagues carried out a retrospective study on the first 62 cases, which included many patients associated with giant LA, and many underwent a second operation. The study resulted in a successful restoration rate of 83.3% of SR off-AADs at the 18-month follow-up26. Recently, the center reached a high annualized volume of CMP of approximately 400 patients per year, with a satisfactory rate of 89.58% freedom from AF at 2 years after surgery27.
In this study, all patients were diagnosed as mirror-image dextrocardia, which means the anatomy of all intracardiac and extracardiac structures is mirror-imaged versus normal, such as the distribution of coronary artery, location of the conducting system, and the geometry of the cardiac valvular structure. The anatomic malposition of situs inversus dextrocardia impacted all technical aspects of the surgical procedure in the intracardiac operation. It made it inconvenient to perform tricuspid annuloplasty and challenging to establish the sophisticated lesion set of CMP-IV. After extensive preoperative evaluation and discussion, we chose cryothermal energy to generate the biatrial lesions of CMP-IV for the first two cases, as it was an energy source capable of producing reliable transmural lesions in a safer and more convenient manner.
However, to accurately understand the anatomical structure and guide surgical ablations in the third case, a 3D printing heart model was made for dynamically displaying the spatial relationship between the specific ablation lines and the key anatomical references, such as the coronary sinus, mitral isthmus, posterior mitral annulus, and right coronary artery. In addition, the rehearsal process provided an intuitive perspective on feasible ablation strategies, including the position, direction, and length for each clamping, to ensure continuous lesion sets and avoid potential damage to the surrounding structures.
We marked the coronary sinus by epicardial cryoablation during the LA lesion set in the first two cases. To protect the circumflex coronary artery, the mitral isthmus lesion is usually adjacent to the P3 cusp of the posterior leaflet of the MV, at about 4 o&#39;clock position on the mitral annulus in the majority of patients21,28. As far as the mirror-image dextrocardia was concerned, we displaced the mitral isthmus lesion in a mirror-image inversion manner to the 8 o&#39;clock position on the mitral annulus for each case in this study (Figure 3A). Similarly, the tricuspid isthmus lesion was displaced from the 2 o&#39;clock to the 10 o&#39;clock position on the tricuspid annulus in these dextrocardia cases (Figure 3B).
Consistent with the experience of others, we had learned that integrity, continuity, and transmurality of CMP-IV are critical for successful cryoablation of AF29. In these rare cases, we operated in a mirror-image inversion manner to integrate the biatrial lesions of CMP-IV and exclusion of LAA. To guarantee the continual lesions, it is important to stretch the atrium to flatten the atrial folds, so that the cryoprobe can adhere closely to the atrium wall during ablation. Transmural ablation was done at -60 &#176;C for 2 min (cooled by nitrous oxide) for each cryolesion.
Additionally, electron microscopy revealed almost full-thickness tissue, except for necrosis of the epicardium of the cryoablated left atrium. Cox and colleagues proclaimed that transmural lesions are ensured with cryothermy at -60 &#176;C for 2 min on an arrested heart, whereas epicardial cryothermy on a beating heart does not guarantee a transmural lesion30. Our experience is consistent with that of Ad and others that it is important to give particular attention to keep an endocardial, bloodless, surgical field during cryoablation for better effect29, especially in the RA ablation while the heart is beating. However, the major disadvantage of using cryothermal energy to ablate remains that there is no qualitative method to detect with certainty whether a given lesion is transmural simultaneously during the cryoablation procedure.
Experience suggests that the surgeon simply had must look at the cryolesion to see when it has become transmural at the time of cryoablation16,30. Thus, during the cryoablation of the first two cases, we waited until the entire desired lesion was frozen transmurally at -60 &#176;C and then counted 2 min by the clock. However, the incomplete or non-full-thickness transmural atrial necrosis in this study may be due to the cryoablation LA epicardium immediately encountering the ice water in the pericardial cavity during mild hypothermic CPB. The heat sink effect of the ice water can limit the epicardial cryolesion formation. Hence, drainage of the ice water during LA cryoablation will be helpful to achieve transmural necrosis. Overall, cryoablation allows for the more convenient achievement of a complete CMP-IV lesion set, and it was efficacious in eliminating AF in these reported cases of situs inversus dextrocardia.
The intraoperative findings in the first two patients revealed that repair of the MV and AV was difficult and infeasible because of chordal fusion and thickened leaflets; hence, prosthetic valve replacement surgeries were performed. We also delineated an optimal method of tricuspid annuloplasty in this study. The Sovering ring, designed asymmetrically according to tricuspid features, was placed elaborately in a mirror-image inversion manner in compliance with tricuspid valve anatomy in each situs inversus dextrocardia (Figure 5). Attention must be paid to remove the holder before fixing the annuloplasty ring. The intraoperative regurgitation water test showed good coaptation of the tricuspid leaflets without leakage. The TTE demonstrated no tricuspid regurgitation before discharge and at mid-term follow-up.
In conclusion, we reported three cases of patients with situs inversus dextrocardia. CMP-IV appeared to be effective in eliminating AF and preserving atrial function in these cases. CMP-IV was performed concomitantly with valvular surgery, safely and effectively. Moreover, the 3D printed heart model helps simulate and modify the CMP-IV procedure, especially in patients with rare malformations, and supports preoperative planning and training for surgical ablation of AF.

Dextrocardia is a rare, congenital cardiac malformation in which the axis of the heart is indexed to the right side of the thoracic cavity. Dextrocardia with situs inversus totalis refers to all visceral organs, including the heart, being mirrored and is extremely rare1,2. Atrial fibrillation (AF) is the most common arrhythmia that affects millions of people and causes substantial morbidity and mortality, especially with respect to the increased risk of stroke3.
A literature survey was unable to demonstrate a definitive approach for the concomitant Cox-Maze procedure (CMP) and valve surgery in dextrocardia with situs inversus. There are only a few reports of mitral valve replacement in cases of dextrocardia with situs solitus and even less in situs inversus4,5,6,7,8,9. However, those strategies are not applicable to tricuspid valve surgery, not to mention the complex CMP-IV in dextrocardia.
This paper reports the surgical techniques and experience in three cases concerning the biatrial lesion set of the CMP-IV operation using cryoablation or radiofrequency ablation concomitantly with valve surgery in situs inversus dextrocardia. All surgeries succeeded in the maintenance of sinus rhythm (SR) at 12 months follow-up to each patient and at 48 months follow-up to the previous two. Electron microscopy was used to investigate the transmurality of the atrial cryoablation.
CASE PRESENTATION:
Patients and preoperative examination 
From February 2016 to September 2020, a 48-year-old female patient, a 55-year-old male patient, and a 39-year-old male patient were successively admitted to the cardiac center with similar complaints of palpitation, dyspnea, and easy fatigability on exertion lasting for years (Table 1). They all denied any familiar history of situs inversus dextrocardia or other cardiac health comorbidities. All patients were referred to electrocardiography (ECG), chest roentgenography (Figure 1), computed tomography (CT), and Doppler transthoracic echocardiography (TTE) routinely for preoperative examination.
Case 1: A 48-year-old woman presented with complaints of palpitation, dyspnea, and easy fatigability on exertion lasting for years. The anamnesis was unremarkable. During the physical examination, a grade 3 systolic blowing murmur was heard in the fifth intercostal space outside the midline of the right clavicle. X-ray plain film and CT scan showed that the contour of the dextrocardia was enlarged and situs inversus totalis. Transesophageal echocardiography revealed moderate to severe mitral regurgitation and mild tricuspid regurgitation after moderate mitral valve prolapse and tricuspid annular dilation. There was no thrombosis, and the diameter of the left atrium was 5.3 cm. AF with a rapid ventricular rate was detected by ECG.
Case 2: A 55-year-old man presented with similar symptoms for years. There was no history of cardiac health comorbidities; however, he had had a stroke about six months ago. On physical examination, a diastolic blowing murmur was heard at the left second intercostal space, radiating to the neck. Plain X-ray and CT scan revealed dextrocardia with an enlarged contour and situs inversus totalis. Transesophageal echocardiography showed moderate aortic valve regurgitation and mild to moderate tricuspid regurgitation following mild aortic prolapse and tricuspid annular dilation. The diameter of the left atrium was 4.5 cm without atrial thrombosis. AF with a rapid ventricular rate was detected by ECG.
Case 3: A 39-year-old male presented with progressive exertional dyspnea and intermittent palpitation without any history of situs inversus dextrocardia or other cardiac health complications. During the physical examination, a grade 3 systolic blowing murmur was heard in the fifth intercostal space outside the midline of the right clavicle. X-ray plain film and CT scan revealed that the contour of dextrocardia was enlarged and situs inversus totalis. Transesophageal echocardiography showed severe mitral valve regurgitation and tricuspid regurgitation after annular enlargement. There was no atrial thrombosis, and the left atrium diameter was 5.8 cm. A 24 h ambulatory ECG demonstrated paroxysmal AF with a total load of 165 min.
Diagnosis, assessment, and plan 
Case 1: A biatrial cryo-Cox-Maze IV procedure (cryo-CMP-IV) with mechanic mitral valve replacement and tricuspid annuloplasty were simultaneously performed.
Case 2: A biatrial cryo-CMP-IV procedure with concomitant mechanic aortic valve (AV) replacement and tricuspid annuloplasty was performed.
Case 3: A biatrial CMP-IV procedure, mitral valvuloplasty, and tricuspid annuloplasty were performed simultaneously.

<table><tbody><tr><td>CryoICE</td><td>AtriCure, Cincinnati, Ohio</td><td>CRYO2</td><td>Cryoablation in case 1 and case 2 was performed exclusively using it with a flexible 10cm in length metal cryoprobe.</td></tr><tr><td>Medtronic Open Pivot Standard mechanical MV</td><td>Medtronic, Minneapolis, Minn</td><td>709291 / MHV 500DM27 STD MITRAL</td><td>A 27-mm MV was adopted in case 1.</td></tr><tr><td>Medtronic Open Pivot Standard mechanical AV</td><td>Medtronic, Minneapolis, Minn</td><td>646871 / MHV 500FA23 STD AORTIC</td><td>A 23-mm AV was adopted in case 2.</td></tr><tr><td>bipolar radiofrequency pen</td><td>AtriCure Inc., Cincinnati, OH</td><td></td><td>Maze-IV in case 3</td></tr><tr><td>bipolar radiofrequency clamps</td><td>AtriCure Inc., Cincinnati, OH</td><td></td><td>Maze-IV in case 3</td></tr><tr><td>Goretex</td><td>W.L. Gore &amp;amp; Associates, Inc., Elkton, Maryland</td><td></td><td>A surgical suture made of polytetrafluoroethylene.</td></tr><tr><td>rigid mitral ring</td><td>Kingstron Bio, Suzhou, China</td><td>Element Force ARM32</td><td>A 32 mm ring was adopted in case 3.</td></tr><tr><td>Tricuspid Sovering Band</td><td>Sorin Group Italia S.r.l., VC, Italy</td><td>SBG0730 / SB30T</td><td>A 30 mm ring was adopted in case 1.</td></tr><tr><td>Tricuspid Sovering Band</td><td>Sorin Group Italia S.r.l., VC, Italy</td><td>SQB0240 / SB30T</td><td>A 30 mm ring was adopted in case 2.</td></tr><tr><td>Tricuspid Sovering Band</td><td>Sorin Group Italia S.r.l., VC, Italy</td><td>SBF0930 / SB28T</td><td>A 28 mm band was adopted in case 3.</td></tr></tbody></table>

cox-maze iv procedure concomitant with valvular surgery in situs inversus dextrocardia: a single-center experience in china

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The use of ablation technologies made the Cox-Maze IV procedure (CMP-IV) technically easier, faster, becoming the gold standard for the surgical treatment of AF. However, the efficacy and safety of CMP-IV in situs inversus dextrocardia are largely unknown. This paper summarizes the CMP-IV procedure performed concomitantly with valvular surgery in patients with situs inversus dextrocardia at this institution.
From February 2016 to September 2020, three dextrocardia patients with persistent AF and valvular diseases were referred to this institution for valvular and CMP-IV surgery. CMP-IV was performed using either cryoablation with a nitrous oxide (N2O)-based cryoprobe or a bipolar radiofrequency clamp and bipolar radiofrequency pen. Mechanical valve replacement or mitral vavuloplasty was performed in another patient in addition to tricuspid annuloplasty. Transmurality of the ablated atrial tissues was evaluated by electron microscopy. Heart function was assessed by transthoracic echocardiography. Cardiac rhythm was monitored by 24 h Holter at 3, 6, 12, 18, 24, and 48 months follow-up. 
All the AF was successfully eliminated in the ablation procedure without recurrence or other complications during hospitalization. The mean bypass and crossclamp times were similar in all the patients. The postoperative ventilator support time, the duration of stay in the ICU, and postoperative residence time were also not significantly different among the patients. Transmural atrial necrosis was detected in the ablated atrial tissues. Sinus rhythm maintenance was achieved at 3, 6, 12, 18, 24, and 48 months follow-up in all the patients. All valve protheses switched freely; no tricuspid regurgitation was observed. The results of the present study demonstrate that the CMP-IV is safe and effective in eliminating AF in dextrocardia patients concomitant with valvular surgery.

Surgical procedure and early postoperative period 
A mechanic MV replacement, tricuspid annuloplasty, and concomitant cryo-CMP-IV were performed simultaneously for the first patient. The second had undergone surgery of mechanic AV replacement, tricuspid annuloplasty, and concomitant cryo-CMP-IV. In the third patient, a biatrial CMP-IV procedure was performed simultaneously with mitral valvuloplasty and tricuspid annuloplasty. All operations were smooth, and each beating heart restored SR after resuscitation (Table 2).
The postoperative course was uneventful. AF did not recur during the hospital stay. The temporary pacemaker was not indicated as atrioventricular block did not develop. No other complications occurred in any patient. TTE revealed no valve regurgitation, and all implanted valvular prostheses worked well. The New York Heart Association (NYHA) class improved from class III preoperatively to class II before discharge. Each patient was discharged in normal SR by ECG and 24 h Holter on postoperative day 12 and day 16, respectively (Table 2).
Follow-up 
All patients were followed up for 1-4 years. At the 3, 6, 12, 18, 24, 36, and 48 months follow-up in the first two and at 3, 6, and 12 months follow-up in the third patient, the maintenance of SR and atrial contractility were demonstrated by 24 h Holter and TTE. All heart functional capacities were improved to NYHA class I by 3 months after surgery (Table 2). To date, all patients have an improved quality of life, and no heart failure, ischemic or hemorrhagic stroke, or other postoperative complications occurred in any patient at the last follow-up visit.
Electron microscopy 
Tissue necrosis was observed by electron microscopy in the full-thickness of the endocardium and almost full-thickness muscularis from the cryoablated left atrium. However, only edema and degeneration were observed in the epicardium and neighboring muscularis. The control sample from the nonablated left atrial tissue showed eumorphism in electron microscopy-normal cell morphology (Figure 7).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/63597/63597fig01.jpg" /> 
Figure 1: Chest roentgenogram of the dextrocardia. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig01large.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/63597/63597fig02.jpg" /> 
Figure 2: Coronary sinus lesion in the mirror-image dextrocardia. The ice ball was formed using cryoablation epicardially. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/63597/63597fig03.jpg" /> 
Figure 3: Cryo-CMP-IV lesion set in the mirror-image dextrocardia. (A) Left atrial lesion set. The mitral isthmus cryolesion was directed toward the 8 o&#39;clock position of the mitral annulus endocardially. The white spot represents the ice ball. (B) Right atrial lesion set. The tricuspid isthmus cryolesion was directed toward 10 o&#39;clock position of the tricuspid annulus endocardially. Abbreviation: Cryo-CMP-IV = cryo-Cox-Maze IV procedure. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/63597/63597fig04.jpg" /> 
Figure 4: Right atrial cryoablation in the mirror-image dextrocardia. The tricuspid isthmus cryolesion was directed toward 10 o&#39;clock position of the tricuspid annulus endocardially. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/63597/63597fig05.jpg" /> 
Figure 5:&#160;3D printed heart model. (A) Preprinting 3D model digital file embedded with designated ablation lines. (B) View of the 3D printed model. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/63597/63597fig06.jpg" /> 
Figure 6: Tricuspid annuloplasty in the mirror-image dextrocardia. The tricuspid ring was implanted in an upside-down and mirror-image inversion manner by interrupted sutures. The holder was removed before implantation of the annuloplasty ring. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig06large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/63597/63597fig07.jpg" /> 
Figure 7: Electron micrographs of cryoablated left atrium. (A, B) Myonecrosis adjoins the endometrium from the female and male patients, respectively. (C, D) Myodegeneration near the epicardium from the female and male, respectively. Scale bars = 5 &#181;m (A, B), 10 &#181;m for C, 20 &#181;m for D. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/63597/63597fig07large.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></td>
			<td>Patient 1</td>
			<td>Patient 2</td>
			<td>Patient 3</td>
		</tr>
		<tr>
			<td>Sex</td>
			<td>Female</td>
			<td>Male</td>
			<td>Male</td>
		</tr>
		<tr>
			<td>Age (years)</td>
			<td>48</td>
			<td>55</td>
			<td>39</td>
		</tr>
		<tr>
			<td>NYHA class</td>
			<td>III</td>
			<td>III</td>
			<td>II</td>
		</tr>
		<tr>
			<td>Anamnesis</td>
			<td>No</td>
			<td>Stroke</td>
			<td>No</td>
		</tr>
		<tr>
			<td>AF pattern</td>
			<td>Long-standing, persistent</td>
			<td>Long-standing, persistent</td>
			<td>Paroxysmal</td>
		</tr>
		<tr>
			<td>AF duration (years)</td>
			<td>5</td>
			<td>3</td>
			<td>2</td>
		</tr>
		<tr>
			<td>TTE</td>
			<td>Mirror-image dextrocardia</td>
			<td>Mirror-image dextrocardia</td>
			<td>Mirror-image dextrocardia</td>
		</tr>
		<tr>
			<td>Left atrial diameter* (mm)</td>
			<td>53/84</td>
			<td>45/69</td>
			<td>58</td>
		</tr>
		<tr>
			<td>Left ventricular diameter (mm)</td>
			<td>67</td>
			<td>61</td>
			<td>54</td>
		</tr>
		<tr>
			<td>Ejection fraction (%)</td>
			<td>46</td>
			<td>49</td>
			<td>68</td>
		</tr>
		<tr>
			<td>Mitral regurgitation</td>
			<td>Moderate to severe</td>
			<td>No</td>
			<td>Moderate</td>
		</tr>
		<tr>
			<td>Aortic regurgitation</td>
			<td>No</td>
			<td>Moderate</td>
			<td>No</td>
		</tr>
		<tr>
			<td>Tricuspid regurgitation</td>
			<td>Mild</td>
			<td>Mild to moderate</td>
			<td>Mild</td>
		</tr>
		<tr>
			<td>CT</td>
			<td>Situs inversus totalis</td>
			<td>Situs inversus totalis</td>
			<td>Situs inversus totalis</td>
		</tr>
		<tr>
			<td colspan="3">* Left atrial diameter is demonstrated as antero-posterior / left-right diameter.</td>
			<td></td>
		</tr>
	</tbody>
</table>
Table 1: Patient preoperative characteristics. Abbreviations: NYHA = New York Heart Association; CT = computed tomography; AF = atrial fibrillation.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td colspan="2"></td>
			<td>Patient 1</td>
			<td>Patient 2</td>
			<td>Patient 3</td>
		</tr>
		<tr>
			<td colspan="2">Concomitant procedures</td>
			<td>Mitral valve replacement</td>
			<td>Aortic valve replacement</td>
			<td>Mitral valvuloplasty</td>
		</tr>
		<tr>
			<td colspan="2"></td>
			<td>Tricuspid annuloplasty</td>
			<td>Tricuspid annuloplasty</td>
			<td>Tricuspid annuloplasty</td>
		</tr>
		<tr>
			<td colspan="2">Aortic cross-clamping time (min)</td>
			<td>95</td>
			<td>92</td>
			<td>140</td>
		</tr>
		<tr>
			<td colspan="2">Cardiopulmonary bypass time (min)</td>
			<td>155</td>
			<td>147</td>
			<td>203</td>
		</tr>
		<tr>
			<td colspan="2">NYHA class before discharge</td>
			<td>II</td>
			<td>II</td>
			<td>II</td>
		</tr>
		<tr>
			<td colspan="2">NYHA class at 3, 6, and 12 months follow-up</td>
			<td>I</td>
			<td>I</td>
			<td>I</td>
		</tr>
		<tr>
			<td colspan="2">NYHA class at 18, 24, and 36 months follow-up</td>
			<td>I</td>
			<td>I</td>
			<td>-</td>
		</tr>
		<tr>
			<td colspan="2">Early AF recurrence</td>
			<td>No</td>
			<td>No</td>
			<td>No</td>
		</tr>
		<tr>
			<td colspan="2">Complications</td>
			<td>No</td>
			<td>No</td>
			<td>No</td>
		</tr>
		<tr>
			<td colspan="2">Temporary pacemaker</td>
			<td>No</td>
			<td>No</td>
			<td>No</td>
		</tr>
		<tr>
			<td colspan="2">TTE</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="2">Left atrial diameter* (mm)</td>
			<td>37/63</td>
			<td>43/55</td>
			<td>36</td>
		</tr>
		<tr>
			<td colspan="2">Left ventricular diameter (mm)</td>
			<td>55</td>
			<td>53</td>
			<td>51</td>
		</tr>
		<tr>
			<td colspan="2">Ejection fraction (%)</td>
			<td>53</td>
			<td>68</td>
			<td>68</td>
		</tr>
		<tr>
			<td colspan="2">Valvular prosthesis function</td>
			<td>Normal</td>
			<td>Normal</td>
			<td>-</td>
		</tr>
		<tr>
			<td colspan="2">Mitral regurgitation</td>
			<td>-</td>
			<td>-</td>
			<td>No</td>
		</tr>
		<tr>
			<td colspan="2">Tricuspid regurgitation</td>
			<td>No</td>
			<td>No</td>
			<td>No</td>
		</tr>
		<tr>
			<td colspan="2">Sinus rhythm restoration</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td colspan="2">3 months follow-up</td>
			<td>Yes</td>
			<td>Yes</td>
			<td>Yes</td>
		</tr>
		<tr>
			<td colspan="2">6 months follow-up</td>
			<td>Yes</td>
			<td>Yes</td>
			<td>Yes</td>
		</tr>
		<tr>
			<td colspan="2">12 months follow-up</td>
			<td>Yes</td>
			<td>Yes</td>
			<td>Yes</td>
		</tr>
		<tr>
			<td colspan="2">18 months follow-up</td>
			<td>Yes</td>
			<td>Yes</td>
			<td>-</td>
		</tr>
		<tr>
			<td colspan="2">24 months follow-up</td>
			<td>Yes</td>
			<td>Yes</td>
			<td>-</td>
		</tr>
		<tr>
			<td colspan="2">36 months follow-up</td>
			<td>Yes</td>
			<td>Yes</td>
			<td>-</td>
		</tr>
		<tr>
			<td colspan="5">* Left atrial diameter is demonstrated as antero-posterior / left-right diameter.</td>
		</tr>
	</tbody>
</table>
Table 2: Operative and postoperative characteristics of cryo-CMP-IV. Abbreviation: Cryo-CMP-IV = cryo-Cox-Maze IV procedure; AF = atrial fibrillation; NYHA = New York Heart Association; TTE = transthoracic echocardiography.

Watch this Scientific Journal Video about Cox-Maze IV Procedure Concomitant with Valvular Surgery In Situs Inversus Dextrocardia: A Single-Center Experience in China at JoVE.com

Cox-Maze IV Procedure Concomitant with Valvular Surgery In Situs Inversus Dextrocardia: A Single-Center Experience in China

We summarize the Cox-Maze IV procedure concomitant with valvular surgery performed in patients with situs inversus dextrocardia at this institution.

Atrial fibrillation (AF) is the most common cardiac arrhythmia. The use of ablation technologies made the Cox-Maze IV procedure (CMP-IV) technically ...

cox-maze-iv-procedure-concomitant-with-valvular-surgery-situs

Nanyang Technological University

Research

JoVE Journal

Medicine

3.3K Views.  Central South University. De werkzaamheid en veiligheid van de Cox-Maze IV-procedure bij dextrocardie zijn grotendeels onbekend. Dit protocol vat de procedure samen gelijktijdig met de vulvulaire operatie die werd uitgevoerd bij drie patiënten met dextrocardie. CMP4 is veilig en effectief in het elimineren van atriumfibrilleren bij dextrocardie.Bovendien helpt het 3D-geprinte hartmodel bij het preoperatief simuleren en plannen van de chirurgische ablatie van AF. Begin de chirurgische procedure voor een mediane...

Video: Cox-Maze IV Procedure Concomitant with Valvular Surgery In Situs Inversus Dextrocardia: A Single-Center Experience in China

Biventricular Assessment of Cardiac Function and Pressure-Volume Loops by Closed-Chest Catheterization in Mice

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) generated by recording both pressure and volume during cardiac catheterization are vital when assessing both systolic and diastolic cardiac function. Left and right heart function are closely related, reflected in ventricular interdependence. Thus, recording biventricular function in the same animal is important to get a complete assessment of cardiac function. In this protocol, a closed chest approach to cardiac catheterization consistent with the way catheterization is performed in patients is adopted in mice. While challenging, the closed chest strategy is a more physiological approach, because opening the chest results in major changes in preload and afterload that create artifacts, most notably a fall in systemic blood pressure. While high-resolution echocardiography is used to assess rodents, cardiac catheterization is invaluable, particularly when assessing diastolic pressures in both ventricles.
Described here is a procedure to perform invasive, closed chest, sequential left and right ventricular pressure-volume (PV) loops in the same animal. PV loops are acquired using&#160;admittance technology with a mouse pressure-volume catheter and pressure-volume system acquisition. The procedure is described, beginning with the neck dissection, which is required to access the right jugular vein and the right carotid artery, to the insertion and positioning of the catheter, and finally the data acquisition. Then, the criteria required to ensure the acquisition of high-quality PV loops are discussed. Finally, the analysis of the left and right ventricular PV loops and the different hemodynamic parameters available to quantify systolic and diastolic ventricular function are briefly described.

Presented here is a protocol to assess biventricular heart function in mice by generating pressure-volume (PV) loops from the right and left ventricle in the same animal using closed chest catheterization. The focus is on the technical aspect of surgery and data acquisition.

Assessment of cardiac function is essential to conduct cardiovascular and pulmonary-vascular preclinical research. Pressure-volume loops (PV loops) ...

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 ...

Operating Transverse Aortic Constriction with Absorbable Suture to Obtain Transient Myocardial Hypertrophy

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate cardiomyocyte hypertrophy and slow down progression to heart failure. For novices, however, the MHP model is usually quite difficult to establish because of the technical obstacles in ventilator operation, opening the chest repeatedly, and bleeding caused by debanding. To facilitate this model, to increase the surgical success rate and to reduce the incidence of bleeding, we switched to absorbable sutures for the first TAC combing with a ventilator-free technique. Using a 2-week absorbable suture, we demonstrated that this procedure could cause significant myocardial hypertrophy in 2 weeks; and 4 weeks after surgery, myocardial hypertrophy was almost completely regressed to the baseline. Using this protocol, the operators could master the MHP model easily with a lower operation mortality.

This protocol presents an improved method to obtain transient myocardial hypertrophy with absorbable suture, simulating left ventricular hypertrophy decrease after removing pressure overload. It could be valuable for the studies on myocardial hypertrophic preconditioning.

Based on twice transverse aortic constrictions (TACs) in mice, it is proved that myocardial hypertrophic preconditioning (MHP) could attenuate ...

A Simplified Stepwise Approach to Echo Guidance during Percutaneous Mitral Valve Repair

Percutaneous transcatheter edge-to-edge reconstruction of the mitral valve is a safe and well-established therapy for severe symptomatic mitral regurgitation in patients with high surgical risk. Echocardiographic guidance in addition to fluoroscopy is the gold standard and should be performed using a standardized technique.
This article lays out our reproducible step by step echocardiographic guide including views, measurements as well as highlighting possible difficulties that may arise during the procedure.
This article provides detailed and chronological echocardiographic views for each step of the procedure, especially preferences between 2D and 3D imaging. If needed, pulse wave, continuous wave and color doppler measurements are described. Furthermore, as there are no official recommendations for the quantification of mitral regurgitation during the percutaneous edge-to-edge-repair procedure, advice is also included for echocardiographic quantification after grasping the mitral leaflets and after device deployment. In addition, the article deals with important echocardiographic views to prevent and deal with possible complications during the procedure.
Echocardiographic guidance during transcatheter mitral valve repair is mandatory. A structured approach improves the collaboration between interventionist and imager and is indispensable for a safe and effective procedure.

This protocol presents in detail how to perform real-time echocardiographic guidance during transcatheter mitral valve repair. The fundamental views and the necessary measurements are described for each stage of the procedure.

Percutaneous transcatheter edge-to-edge reconstruction of the mitral valve is a safe and well-established therapy for severe symptomatic mitral ...

Modifications of the Langendorff Method for Simultaneous Isolation of Atrial and Ventricular Myocytes from Adult Mice

A single cardiomyocyte is a vital tool in the cellular and subcellular level studies of cardiac biology and diseases as a fundamental unit of contraction and electrical activity. Hence, isolating viable, high-quality cardiomyocytes from the heart is the initial and most crucial experimental step. Comparing the various protocols for isolating the cardiomyocytes of adult mice, the Langendorff retrograde perfusion is the most successful and reproducible method reported in the literature, especially for isolating ventricular myocytes. However, isolating quality atrial myocytes from the perfused heart remains challenging, and few successful isolation reports are available. Solving this complicated problem is extremely important because apart from ventricular disease, atrial disease accounts for a large part of heart diseases. Therefore, further investigations on the cellular level to reveal the mechanisms are warranted. In this paper, a protocol based on the Langendorff retrograde perfusion method is introduced and some modifications in the depth of aorta cannulation and the steps that may affect the digestion process to isolate atrial and ventricular myocytes were simultaneously made. Moreover, the isolated cardiomyocytes are confirmed to be amenable to patch clamp investigation.

This protocol describes modifications of the Langendorff method including the depth of aorta cannulation for simultaneous Isolation of atrial and ventricular myocytes from adult mice.

A single cardiomyocyte is a vital tool in the cellular and subcellular level studies of cardiac biology and diseases as a fundamental unit of contraction ...

Generation and Characterization of Right Ventricular Myocardial Infarction Induced by Permanent Ligation of the Right Coronary Artery in Mice

Right ventricular infarction (RVI) is a common presentation in clinical practice. Severe RVI can lead to fatal hemodynamic dysfunction and arrhythmia. In contrast to the extensively used mouse myocardial infarction (MI) model generated by left coronary artery ligation, the RVI mouse model is rarely employed due to the difficulty associated with model generation. Research on the mechanisms and treatment of RVI-induced RV remodeling and dysfunction requires animal models to mimic the pathophysiology of RVI in patients. This study introduces a feasible procedure for RVI model generation in C57BL/6J mice. Further, this model was characterized based on the following: infarct size evaluation at 24 h after MI, assessment of cardiac remodeling and function with echocardiography, RV hemodynamics assessment, and histology of the infarct zone at 4 weeks after RVI. In addition, a coronary vasculature cast was performed to observe the coronary arterial arrangement in RV. This mouse model of RVI would facilitate the research on mechanisms of right heart failure and seek new therapeutic targets of RV remodeling.

There are several differences between the right and left ventricles. However, the pathophysiology of right ventricular infarction (RVI) has not been clarified. In the present protocol, a reproducible method for RVI mouse model generation is introduced, which may provide a means to explain the mechanism of RVI.

Right ventricular infarction (RVI) is a common presentation in clinical practice. Severe RVI can lead to fatal hemodynamic dysfunction and arrhythmia. In ...

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

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

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

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

Fully Endoscopic Mitral Valve Repair with Percutaneous Cannulation of Groin Vessels

Endoscopic mitral valve surgery (EMS) has become a standard of care at specialized heart centers, further reducing surgical trauma compared to a traditional minimally invasive, thoracotomy-based approach. Exposure of the groin vessels for the establishment of cardiopulmonary bypass (CPB) via surgical cutdown in minimally invasive surgery (MIS) may result in wound healing disorders or seroma formation. The avoidance of surgical exposure of the groin vessels by using fully percutaneous techniques for the insertion of a CPB cannula with the implementation of vascular pre-closure devices has the potential to reduce these complications and improve clinical results. Herein, we present the utilization of a novel plug based vacsular closure device with a resobable collagen plug and the absence of suture material for closure of the arterial access for CPB in MIS. While this device was initially predominantly used in transcatheter aortic valve implantation (TAVI) procedures, with its safety and feasibility shown, we herein show that it can be used in CPB cannulation, since it is capable of closing arterial access sites up to 25 French (Fr.) in size. This device may be suitable to significantly reduce groin complications in MIS and simplify the establishment of CPB. Here, we describe the fundamental steps of EMS, including percutaneous groin cannulation and decannulation using a vascular closure device.

This protocol demonstrates in detail how to perform fully endoscopic mitral valve surgery (EMS) with percutaneous cannulation of the groin vessels, using a percutaneous plug-based vascular closure device. Fundamental steps and useful instructions are described in detail for each step.

Endoscopic mitral valve surgery (EMS) has become a standard of care at specialized heart centers, further reducing surgical trauma compared to a ...

Surgically Induced Cardiac Volume Overload by Aortic Regurgitation in Mouse

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

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

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

Biology

A Modified Technique for Transverse Aortic Constriction in Mice

Transverse aortic constriction (TAC) is a frequently used surgery in research regarding heart failure and cardiac hypertrophy based on the formation of pressure overload in mouse models. The main challenge of this procedure is to clearly visualize the transverse aortic arch and precisely band the target vessel. Classical approaches perform a partial thoracotomy to expose the transverse aortic arch. However, it is an open-chest model that causes a rather large surgical trauma and requires a ventilator during the surgery. To prevent unnecessary trauma and simplify the operating procedure, the aortic arch is approached via the proximal proportion of the sternum, reaching and binding the target vessel using a small self-made retractor that contains a snare. This procedure can be conducted without entering the pleura cavity and does not need a ventilator or microsurgical operation, which leaves the mice with physiological breathing patterns, simplifies the procedure, and significantly reduces operation time. Due to the less invasive approach and less operation time, mice can undergo fewer stress reactions and recover rapidly.

The present protocol describes a modified and simplified technique with a minimally invasive transverse aortic constriction (TAC) procedure using a self-made retractor. This procedure can be conducted without a ventilator or microscope and introduces pressure overload, eventually leading to cardiac hypertrophy or heart failure.

Transverse aortic constriction (TAC) is a frequently used surgery in research regarding heart failure and cardiac hypertrophy based on the formation of ...

Cox-Maze IV Procedure Concomitant with Valvular Surgery In Situs Inversus Dextrocardia: A Single-Center Experience in China

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