Name: four-dimensional computed tomography-guided valve sizing for transcatheter pulmonary valve replacement
Uploaded: 2022-01-20T14:30:00
Description: Watch this Scientific Journal Video about Four-Dimensional Computed Tomography-Guided Valve Sizing for Transcatheter Pulmonary Valve Replacement at JoVE.com

Xiaolin Sun and Yimeng Hao contributed equally to this manuscript and share first authorship. Heartfelt appreciation is extended to all who contributed to this work, both past and present members. This work was supported by grants from the German Federal Ministry for Economic Affairs and Energy, EXIST - Transfer of Research (03EFIBE103). Xiaolin Sun and Yimeng Hao are supported by the China Scholarship Council (Xiaolin Sun- CSC: 201908080063, Yimeng Hao-CSC: 202008450028).

All cardiac CT data were obtained from GrOwnValve preclinical trials with the approval of the legal and ethical committee of the Regional Office for Health and Social Affairs, Berlin (LAGeSo). All animals received humane care in compliance with the guidelines of the European and German Societies of Laboratory Animal Science (FELASA, GV-SOLAS). In this study, the Pre-CT from sheep J was chosen to illustrate the procedures.
1. Perform 3D cardiac CT in sheep
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	<li>Intraveno...

<ol>
	<li>Baumgartner, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2020+ESC+Guidelines+for+the+management+of+adult+congenital+heart+disease:+The+Task+Force+for+the+management+of+adult+congenital+heart+disease+of+the+European+Society+of+Cardiology+(ESC).+Endorsed+by:+Association+for+European+Paediatric+and+Congenital+Cardiology+(AEPC),+International+Society+for+Adult+Congenital+Heart+Disease.">2020 ESC Guidelines for the management of adult congenital heart disease: The Task Force for the management of adult congenital heart disease of the European Society of Cardiology (ESC). Endorsed by: Association for European Paediatric and Congenital Cardiology (AEPC), International Society for Adult Congenital Heart Disease.</a> European Heart Journal. 42 (6), 563-645 (2021).</li><li>Gales, J., Krasuski, R. A., Fleming, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcatheter+Valve+Replacement+for+Right-sided+Valve+Disease+in+Congenital+Heart+Patients.">Transcatheter Valve Replacement for Right-sided Valve Disease in Congenital Heart Patients.</a> Progress in Cardiovascular Diseases. 61 (3-4), 347-359 (2018).</li><li>Goldstein, B. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adverse+Events,+Radiation+Exposure,+and+Reinterventions+Following+Transcatheter+Pulmonary+Valve+Replacement.">Adverse Events, Radiation Exposure, and Reinterventions Following Transcatheter Pulmonary Valve Replacement.</a> Journal of the American College of Cardiology. 75 (4), 363-376 (2020).</li><li>Ansari, M. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Percutaneous+Pulmonary+Valve+Implantation:+Present+Status+and+Evolving+Future.">Percutaneous Pulmonary Valve Implantation: Present Status and Evolving Future.</a> Journal of the American College of Cardiology. 66 (20), 2246-2255 (2015).</li><li>Nordmeyer, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+and+midterm+outcomes+of+the+post-approval+MELODY+Registry:+a+multicentre+registry+of+transcatheter+pulmonary+valve+implantation.">Acute and midterm outcomes of the post-approval MELODY Registry: a multicentre registry of transcatheter pulmonary valve implantation.</a> European Heart Journal. 40 (27), 2255-2264 (2019).</li><li>Shahanavaz, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intentional+Fracture+of+Bioprosthetic+Valve+Frames+in+Patients+Undergoing+Valve-in-Valve+Transcatheter+Pulmonary+Valve+Replacement.">Intentional Fracture of Bioprosthetic Valve Frames in Patients Undergoing Valve-in-Valve Transcatheter Pulmonary Valve Replacement.</a> Circulation. Cardiovascular Interventions. 11 (8), 006453 (2018).</li><li>Binder, R. K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+integration+of+a+multidetector+computed+tomography+annulus+area+sizing+algorithm+on+outcomes+of+transcatheter+aortic+valve+replacement:+a+prospective,+multicenter,+controlled+trial.">The impact of integration of a multidetector computed tomography annulus area sizing algorithm on outcomes of transcatheter aortic valve replacement: a prospective, multicenter, controlled trial.</a> Journal of the American College of Cardiology. 62 (5), 431-438 (2013).</li><li>Curran, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computed+tomography+guided+sizing+for+transcatheter+pulmonary+valve+replacement.">Computed tomography guided sizing for transcatheter pulmonary valve replacement.</a> International Journal of Cardiology. Heart &amp; Vasculature. 29, 100523 (2020).</li><li>Kidoh, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vectors+through+a+cross-sectional+image+(VCI):+A+visualization+method+for+four-dimensional+motion+analysis+for+cardiac+computed+tomography.">Vectors through a cross-sectional image (VCI): A visualization method for four-dimensional motion analysis for cardiac computed tomography.</a> Journal of Cardiovascular Computed Tomography. 11 (6), 468-473 (2017).</li><li>Schievano, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Four-dimensional+computed+tomography:+a+method+of+assessing+right+ventricular+outflow+tract+and+pulmonary+artery+deformations+throughout+the+cardiac+cycle.">Four-dimensional computed tomography: a method of assessing right ventricular outflow tract and pulmonary artery deformations throughout the cardiac cycle.</a> European Radiology. 21 (1), 36-45 (2011).</li><li>Lantz, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intracardiac+Flow+at+4D+CT:+Comparison+with+4D+Flow+MRI.">Intracardiac Flow at 4D CT: Comparison with 4D Flow MRI.</a> Radiology. 289 (1), 51-58 (2018).</li><li>Kobayashi, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Quantitative+analysis+of+regional+endocardial+geometry+dynamics+from+4D+cardiac+CT+images:+endocardial+tracking+based+on+the+iterative+closest+point+with+an+integrated+scale+estimation.">Quantitative analysis of regional endocardial geometry dynamics from 4D cardiac CT images: endocardial tracking based on the iterative closest point with an integrated scale estimation.</a> Physics in Medicine and Biology. 64 (5), 055009 (2019).</li><li>Grbic, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complete+valvular+heart+apparatus+model+from+4D+cardiac+CT.">Complete valvular heart apparatus model from 4D cardiac CT.</a> Medical Image Analysis. 16 (5), 1003-1014 (2012).</li><li>Hamdan, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deformation+dynamics+and+mechanical+properties+of+the+aortic+annulus+by+4-dimensional+computed+tomography:+insights+into+the+functional+anatomy+of+the+aortic+valve+complex+and+implications+for+transcatheter+aortic+valve+therapy.">Deformation dynamics and mechanical properties of the aortic annulus by 4-dimensional computed tomography: insights into the functional anatomy of the aortic valve complex and implications for transcatheter aortic valve therapy.</a> Journal of the American College of Cardiology. 59 (2), 119-127 (2012).</li><li>Kim, S., Chang, Y., Ra, J. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cardiac+Motion+Correction+for+Helical+CT+Scan+With+an+Ordinary+Pitch.">Cardiac Motion Correction for Helical CT Scan With an Ordinary Pitch.</a> IEEE Transactions on Medical Imaging. 37 (7), 1587-1596 (2018).</li></ol>

To date, this is the first study to illustrate a patient-specific measurement of the morphology and dynamic parameters of RVOT-PA with a straightened cardiac model generated from a 4D CT sequence, which can be applied to predict the optimal valve size for TPVR. This methodology wasillustrated using sheep J Pre-CT imaging to obtain the dynamic deformations, right ventricular volumes, right ventricular function, and magnitude of RVOT/PA change from the RVOT to the pulmonary trunk in five planes at every 10% reconstruction ...

Dysfunction of the right ventricular outflow tract (RVOT) and pulmonary valve abnormalities are two of the most frequent consequences of severe congenital heart disease, for example, patients with repaired tetralogy of Fallot (TOF), certain types of double outlet right ventricle (DORV), and transposition of the great arteries1,2,3. The majority of these patients face multiple operations throughout their lives and along with advancing age, the risks of complexity and comorbidities increase. These patients may benefit from transcatheter pulmonary valve replacement (TPVR) as a minimally invasive treatment4. To date, there has been a steady growth in the number of patients undergoing TPVR and several thousands of these procedures have been performed worldwide. Compared with traditional open-heart surgery, TPVR requires a more accurate anatomical measurement of the xenograft or homograft from the right ventricle (RV) to pulmonary artery (PA), as well as the repair of pulmonary and RVOT stenosis via transannular patch, by computed tomography angiography (CTA) prior to intervention and to ensure that the patients are free from stent fracture and paravalvular leak (PVL)5,6.
A prospective, multicenter study demonstrated that a multidetector CT annular sizing algorithm played an important role in selecting the appropriate valve size, which could decrease the degree of paravalvular regurgitation7. In recent years, quantitative analysis has been more and more applied in clinical medicine. Quantitative analysis has enormous potential to enable objective and correct interpretation of clinical imaging and to verify that patients are free of stent fracture and paravalvular leak, which can enhance patient-specific therapy and treatment response evaluation. In previous clinical practice, it was feasible to reconstruct CT imaging from three planes (sagittal, coronal, and axial) with two-dimensional (2D) CT to obtain a visualization model8. Contrast-enhanced electrocardiogram (ECG)-gated CT has become more important in the evaluation of RVOT/PA 3D morphology and function, as well as in the identification of patients with a suitable RVOT implantation site that is capable of maintaining TPVR stability throughout the cardiac cycle9,10.
However, in the contemporary standard clinical and preclinical settings, the acquired 4D CT data are usually translated into 3D planes for manual quantification and visual evaluation which cannot show 3D/4D dynamic information11. Furthermore, even with 3D information, the measurements obtained from multiplanar reconstruction (MPR) have various limitations, such as poor quality of visualization and lack of dynamic deformation due to the different directions of blood flow in the right heart12. Measurements are time-consuming to gather and prone to mistakes, as 2D alignment and sectioning can be imprecise, resulting in misinterpretation and distensibility. Currently, there is no consensus on which measurement of RVOT-PA could reliably provide accurate information about the indications and valve sizing for TPVR in patients with dysfunctional RVOT and/or pulmonary valve disease.
In this study, the method for measuring RVOT-PA using a straightened right heart model via a 4D cardiac CT sequence is provided to determine how best to characterize the 3D deformations of RVOT-PA throughout the cardiac cycle. The spatio-temporal correlation imaging was completed by including the temporal dimension and, therefore, were able to measure variations in RVOT-PA magnitude. Additionally, the deformation of the straightened models could positively impact TPVR valve sizing and procedural planning.

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four-dimensional computed tomography-guided valve sizing for transcatheter pulmonary valve replacement

The measurements of the right ventricle (RV) and pulmonary artery (PA), for selecting the optimal prosthesis size for transcatheter pulmonary valve replacement (TPVR), vary considerably. Three-dimensional (3D) computed tomography (CT) imaging for device size prediction is insufficient to assess the displacement of the right ventricular outflow tract (RVOT) and PA, which could increase the risk of stent misplacement and paravalvular leak. The aim of this study is to provide a dynamic model to visualize and quantify the anatomy of the RVOT to PA over the entire cardiac cycle by four-dimensional (4D) cardiac CT reconstruction to obtain an accurate quantitative evaluation of the required valve size. In this pilot study, cardiac CT from sheep J was chosen to illustrate the procedures. 3D cardiac CT was imported into 3D reconstruction software to build a 4D sequence which was divided into eleven frames over the cardiac cycle to visualize the deformation of the heart. Diameter, cross-sectional area, and circumference of five imaging planes at the main PA, sinotubular junction, sinus, basal plane of the pulmonary valve (BPV), and RVOT were measured at each frame in 4D straightened models prior to valve implantation to predict the valve size. Meanwhile, dynamic changes in the RV volume were also measured to evaluate right ventricular ejection fraction (RVEF). 3D measurements at the end of the diastole were obtained for comparison with the 4D measurements. In sheep J, 4D CT measurements from the straightened model resulted in the same choice of valve size for TPVR (30 mm) as 3D measurements. The RVEF of sheep J from pre-CT was 62.1 %. In contrast with 3D CT, the straightened 4D reconstruction model not only enabled accurate prediction for valve size selection for TPVR but also provided an ideal virtual reality, thus presenting a promising method for TPVR and the innovation of TPVR devices.

In sheep J, the 4D total heart and right heart models were successfully generated from the 4D cardiac CT sequence which showed the deformation throughout the entire cardiac cycle. For better visualization, the whole deformation of the beating heart and right heart is exhibited in every direction in Figure 3 - Figure 4 and in Video 1 - Video 2.
The str...

Watch this Scientific Journal Video about Four-Dimensional Computed Tomography-Guided Valve Sizing for Transcatheter Pulmonary Valve Replacement at JoVE.com

Four-Dimensional Computed Tomography-Guided Valve Sizing for Transcatheter Pulmonary Valve Replacement

This study assessed a new methodology with a straightened model generated from the four-dimensional cardiac computed tomography sequence to obtain the desired measurements for valve sizing in the application of transcatheter pulmonary valve replacement.

The measurements of the right ventricle (RV) and pulmonary artery (PA), for selecting the optimal prosthesis size for transcatheter pulmonary valve ...

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Computed Tomography-guided Time-domain Diffuse Fluorescence Tomography in Small Animals for Localization of Cancer Biomarkers

Small animal fluorescence molecular imaging (FMI) can be a powerful tool for preclinical drug discovery and development studies1. However, light absorption by tissue chromophores (e.g., hemoglobin, water, lipids, melanin) typically limits optical signal propagation through thicknesses larger than a few millimeters2. Compared to other visible wavelengths, tissue absorption for red and near-infrared (near-IR) light absorption dramatically decreases and non-elastic scattering becomes the dominant light-tissue interaction mechanism. The relatively recent development of fluorescent agents that absorb and emit light in the near-IR range (600-1000 nm), has driven the development of imaging systems and light propagation models that can achieve whole body three-dimensional imaging in small animals3.
Despite great strides in this area, the ill-posed nature of diffuse fluorescence tomography remains a significant problem for the stability, contrast recovery and spatial resolution of image reconstruction techniques and the optimal approach to FMI in small animals has yet to be agreed on. The majority of research groups have invested in charge-coupled device (CCD)-based systems that provide abundant tissue-sampling but suboptimal sensitivity4-9, while our group and a few others10-13 have pursued systems based on very high sensitivity detectors, that at this time allow dense tissue sampling to be achieved only at the cost of low imaging throughput. Here we demonstrate the methodology for applying single-photon detection technology in a fluorescence tomography system to localize a cancerous brain lesion in a mouse model.
The fluorescence tomography (FT) system employed single photon counting using photomultiplier tubes (PMT) and information-rich time-domain light detection in a non-contact conformation11. This provides a simultaneous collection of transmitted excitation and emission light, and includes automatic fluorescence excitation exposure control14, laser referencing, and co-registration with a small animal computed tomography (microCT) system15. A nude mouse model was used for imaging. The animal was inoculated orthotopically with a human glioma cell line (U251) in the left cerebral hemisphere and imaged 2 weeks later. The tumor was made to fluoresce by injecting a fluorescent tracer, IRDye 800CW-EGF (LI-COR Biosciences, Lincoln, NE) targeted to epidermal growth factor receptor, a cell membrane protein known to be overexpressed in the U251 tumor line and many other cancers18. A second, untargeted fluorescent tracer, Alexa Fluor 647 (Life Technologies, Grand Island, NY) was also injected to account for non-receptor mediated effects on the uptake of the targeted tracers to provide a means of quantifying tracer binding and receptor availability/density27. A CT-guided, time-domain algorithm was used to reconstruct the location of both fluorescent tracers (i.e., the location of the tumor) in the mouse brain and their ability to localize the tumor was verified by contrast-enhanced magnetic resonance imaging.
Though demonstrated for fluorescence imaging in a glioma mouse model, the methodology presented in this video can be extended to different tumor models in various small animal models potentially up to the size of a rat17.

Diffuse fluorescence tomography offers a relatively low-cost and potentially high-throughout approach to preclinical in vivo tumor imaging. The methodology of optical data collection, calibration, and image reconstruction is presented for a computed tomography-guided non-contact time-domain system using fluorescent targeting of the tumor biomarker epidermal growth factor receptor in a mouse glioma model.

Small animal fluorescence molecular imaging (FMI) can be a powerful tool for preclinical drug discovery and development studies1. However, light ...

Transplantation of Pulmonary Valve Using a Mouse Model of Heterotopic Heart Transplantation

Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed results. However, the cellular and molecular mechanisms of the neotissue development, valve thickening, and stenosis development are not researched extensively. To answer the above questions, we developed a murine heterotopic heart valve transplantation model. A heart valve was harvested from a valve donor mouse and transplanted to a heart donor mouse. The heart with a new valve was transplanted heterotopically to a recipient mouse. The transplanted heart showed its own heartbeat, independent of the recipient&#8217;s heartbeat. The blood flow was quantified using a high frequency ultrasound system with a pulsed wave Doppler. The flow through the implanted pulmonary valve showed forward flow with minimal regurgitation and the peak flow was close to 100 mm/sec. This murine model of heart valve transplantation is highly versatile, so it can be modified and adapted to provide different hemodynamic environments and/or can be used with various transgenic mice to study neotissue development in a tissue engineered heart valve.

In order to understand the cellular and molecular mechanisms underlying neotissue formation and stenosis development in tissue engineered heart valves, a murine model of heterotopic heart valve transplantation was developed. A pulmonary heart valve was transplanted to recipient using the heterotopic heart transplantation technique.

Tissue engineered heart valves, especially decellularized valves, are starting to gain momentum in clinical use of reconstructive surgery with mixed ...

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

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

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

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

Standardized Technique of Aortic Valve Re-implantation for Valve-sparing Aortic Root Replacement

Despite the obvious advantages of the preservation of a normal aortic valve during aortic root replacement, the complexity of valve sparing procedures prevents a number of cardiac surgeons from incorporating them into their practice. The aim of this protocol is to describe a simplified and user-friendly technique of an aortic valve-sparing root replacement (VSRR) procedure by re-implantation of the aortic valve. Proper selection of patients and limitations of the technique are discussed.
In 54 consecutive patients, normal appearing aortic valves were re-implanted in a commercially available polyester prosthesis with pre-shaped sinuses by a simplified and standardized technique. Placement of the first row of the proximal suture line, choice of the prosthesis size, and adjustment of the height of the commissures of the patient to the fixed height of the sinus portion of the prosthesis were slightly modified from the reference techniques with the aim of increasing its feasibility for use by other cardiac surgeons. Early mortality and morbidity as well as 5-year survival, freedom from aortic valve reoperation, and freedom from recurrent moderate regurgitation were collected in all patients.
Thirty-day mortality, re-sternotomy for bleeding, re-sternotomy for mediastinitis, and the incidence of stroke were very low, 1.8% for each (1 of 54). No patient required permanent pace-maker implantation. At 5 years, survival, freedom from aortic valve reoperation, and freedom from recurrent moderate regurgitation were 97.5%, 95.2%, and 91.6%, respectively.
Mid-term results of our standardized technique of re-implantation of the aortic valve for valve-sparing aortic root replacement are very good and compare with more complex techniques reported by experienced surgeons. By following the present protocol of the standardized re-implantation technique, a greater number of cardiac surgeons can perform this procedure with comparable good results.

Valve-sparing aortic root replacement has the advantage of preserving the patient&#39;s own aortic valve. The complexity of the reported techniques to date restricts their use to a limited number of cardiac surgeons. This protocol describes step-by-step a standardized technique reproducible by a greater number of cardiac surgeons.

Despite the obvious advantages of the preservation of a normal aortic valve during aortic root replacement, the complexity of valve sparing procedures ...

Technique and Patient Selection Criteria of Right Anterior Mini-Thoracotomy for Minimal Access Aortic Valve Replacement

Aortic valve stenosis has become the most prevalent valvular heart disease in developed countries, and is due to the aging of these populations. The incidence of the pathology increases with growing age after 65 years. Conventional surgical aortic valve replacement through median sternotomy has been the gold standard of patient care for symptomatic aortic valve stenosis. However, as the risk profile of patients worsens, other therapeutic strategies have been introduced in an attempt to maintain the excellent results obtained by the established surgical treatment. One of these approaches is represented by transcatheter aortic valve implantation. Although the outcomes of high-risk patients undergoing treatment for symptomatic aortic valve stenosis have improved with transcatheter aortic valve replacement, many patients with this condition remain candidates for surgical aortic valve replacement. In order to reduce the surgical trauma in patients who are candidates for surgical aortic valve replacement, minimally invasive approaches have garnered interest during the past decade. Since the introduction of right anterior thoracotomy for aortic valve replacement in 1993, right anterior mini-thoracotomy and upper hemi-sternotomy have become the predominant incisional approaches among cardiac surgeons performing minimal access aortic valve replacement. Beside the location of the incision, the arterial cannulation site represents the second major landmark of minimal access techniques for aortic valve replacement. The two most frequently used arterial cannulation sites include central aortic and peripheral femoral approaches. With the purpose of reducing surgical trauma in these patients, we have opted for a right anterior mini-thoracotomy approach with a central aortic cannulation site. This protocol describes in detail a technique for minimally invasive aortic valve replacement and provides recommendations for patient selection criteria, including cardiac computer tomography measurements. The indications and limitations of this technique, as well as its alternatives, are discussed.

The goal of this protocol is to describe in detail the technique of minimally invasive aortic valve replacement through a right anterior mini-thoracotomy and central aortic cannulation. This technique can potentially enhance patients&#39; comfort and, by reducing post-operative morbidity, promote lowering the length of stay and global costs.

Aortic valve stenosis has become the most prevalent valvular heart disease in developed countries, and is due to the aging of these populations. The ...

Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to facilitate anatomical guidance is of huge interest for complex cardiac interventions like TAVI procedures with cerebral protection. Co-registration of CTA and XR has been introduced either based on additional intraoperative non-/contrast-enhanced cone-beam computed tomography (CBCT) or two separate aortograms. With the related increase of radiation exposure and/or contrast agent (CA) dose, a potential additional risk for the patient is introduced. Here, we propose a modified co-registration approach making use of arteriograms of the iliofemoral arteries, routinely performed during the femoral puncture and sheath introduction. On-the-fly refinement of the co-registration during the on-going procedure enables accurate co-registration without any additional angiograms, thus reducing CA, XR dose and procedure time, while simultaneously improving operator confidence and procedure safety.

The aim of this study was to improve the co-registration for image fusion (IF) of pre-interventional CT data with real-time x-ray (XR) fluoroscopy during transfemoral transcatheter aortic valve implantation (TAVI).

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to ...

An Image Guided Transapical Mitral Valve Leaflet Puncture Model of Controlled Volume Overload from Mitral Regurgitation in the Rat

Mitral regurgitation (MR) is a widely prevalent heart valve lesion, which causes cardiac remodeling and leads to congestive heart failure. Though the risks of uncorrected MR and its poor prognosis are known, the longitudinal changes in cardiac function, structure and remodeling are incompletely understood. This knowledge gap has limited our understanding of the optimal timing for MR correction, and the benefit that early versus late MR correction may have on the left ventricle. To investigate the molecular mechanisms that underlie left ventricular remodeling in the setting of MR, animal models are necessary. Traditionally, the aorto-caval fistula model has been used to induce volume overload, which differs from clinically relevant lesions such as MR. MR represents a low-pressure volume overload hemodynamic stressor, which requires animal models that mimic this condition. Herein, we describe a rodent model of severe MR in which the anterior leaflet of the rat mitral valve is perforated with a 23G needle, in a beating heart, with echocardiographic image guidance. The severity of MR is assessed and confirmed with echocardiography, and the reproducibility of the model is reported.&#160;&#160;

A rodent model of left heart volume overload from mitral regurgitation is reported. Mitral regurgitation of controlled severity is induced by advancing a needle of defined dimensions into the anterior leaflet of the mitral valve, in a beating heart, with ultrasound guidance.&#160;

Mitral regurgitation (MR) is a widely prevalent heart valve lesion, which causes cardiac remodeling and leads to congestive heart failure. Though the ...

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 ...

A Simplified Model for Heterotopic Heart Valve Transplantation in Rodents

There is an urgent clinical need for heart valve replacements that can grow in children. Heart valve transplantation is proposed as a new type of transplant with the potential to deliver durable heart valves capable of somatic growth with no requirement for anticoagulation. However, the immunobiology of heart valve transplants remains unexplored, highlighting the need for animal models to study this new type of transplant. Previous rat models for heterotopic aortic valve transplantation into the abdominal aorta have been described, though they are technically challenging and costly. For addressing this challenge, a renal subcapsular transplant model was developed in rodents as a practical and more straightforward method for studying heart valve transplant immunobiology. In this model, a single aortic valve leaflet is harvested and inserted into the renal subcapsular space. The kidney is easily accessible, and the transplanted tissue is securely contained in a subcapsular space that is well vascularized and can accommodate a variety of tissue sizes. Furthermore, because a single rat can provide three donor aortic leaflets and a single kidney can provide multiple sites for transplanted tissue, fewer rats are required for a given study. Here, the transplantation technique is described, providing a significant step forward in studying the transplant immunology of heart valve transplantation.

This protocol describes a simple and efficient method for the transplantation of aortic valve leaflets under the renal capsule to allow for the study of alloreactivity of heart valves.

There is an urgent clinical need for heart valve replacements that can grow in children. Heart valve transplantation is proposed as a new type of ...

Combining 3D-Printing and Electrospinning to Manufacture Biomimetic Heart Valve Leaflets

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds with adjustable properties. The aim of this study was to create multilayered scaffolds mimicking the architectural fiber characteristics of human heart valve leaflets using conductive 3D-printed collectors.
Models of aortic valve cusps were created using commercial computer-aided design (CAD) software. Conductive polylactic acid was used to fabricate 3D-printed leaflet templates. These cusp negatives were integrated into a specifically designed, rotating electrospinning mandrel. Three layers of polyurethane were spun onto the collector, mimicking the fiber orientation of human heart valves. Surface and fiber structure was assessed with a scanning electron microscope (SEM). The application of fluorescent dye additionally permitted the microscopic visualization of the multilayered fiber structure. Tensile testing was performed to assess the biomechanical properties of the scaffolds.
3D-printing of essential parts for the electrospinning rig was possible in a short time for a low budget. The aortic valve cusps created following this protocol were three-layered, with a fiber diameter of 4.1 &#177; 1.6 &#181;m. SEM imaging revealed an even distribution of fibers. Fluorescence microscopy revealed individual layers with differently aligned fibers, with each layer precisely reaching the desired fiber configuration. The produced scaffolds showed high tensile strength, especially along the direction of alignment. The printing files for the different collectors are available as Supplemental File 1, Supplemental File 2, Supplemental File 3, Supplemental File 4, and Supplemental File 5.
With a highly specialized setup and workflow protocol, it is possible to mimic tissues with complex fiber structures over multiple layers. Spinning directly on 3D-printed collectors creates considerable flexibility in manufacturing 3D shapes at low production costs.

The presented method offers an innovative way for engineering biomimetic fiber structures in three-dimensional (3D) scaffolds (e.g., heart valve leaflets). 3D-printed, conductive geometries were used to determine shape and dimensions. Fiber orientation and characteristics were individually adjustable for each layer. Multiple samples could be manufactured in one setup.

Electrospinning has become a widely used technique in cardiovascular tissue engineering as it offers the possibility to create (micro-)fibrous scaffolds ...