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The porcine model is a commonly used animal model in cardiovascular research. Along with new innovative operative techniques, choice of the optimal imaging technique is crucial. Transesophageal echocardiography (TEE) is a reliable imaging tool is highly important in a large number of experimental evaluations. But so far, TEE data for swine are limited, and few standard values have been established for the porcine model. The experience and baseline results for TEE in 45 swine are presented in this study. A full TEE examination was conducted in 45 German landrace or German large white swine, with an average body weight of 49 ± 3 kg, before experimental off-pump mitral valved stent implantation. Additionally hemodynamic measurements were evaluated. The valve implantation procedure was guided solely by real-time 3-D TEE. Baseline values of standard echocardiographic parameters are provided and, where appropriate, compared with human reference values. TEE proved to be an adequate imaging technique in this experimental porcine animal model. The baseline TEE and hemodynamic parameters established for the widely used porcine model can serve as a reference in future studies., (Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.)

Objectives: Despite recent achievements, implantation of a transcatheter mitral valved stent remains challenging. In this study, we present a different approach for implantation of a percutaneous mitral valved stent., Methods: Percutaneous transapical access is combined with, respectively, a left-transatrial, right-transatrial/transseptal or transfemoral/transseptal approach for mitral valve stent implantation and secure fixation. The apical fixation and occlusion are ensured with an Amplatzer occluder. This novel approach was tested in 22 porcine hearts in an in vitro setting under the guidance of fluoroscopy ( n  = 11) and endoscopy ( n  = 11). The in vitro setup included continuous flushing at 37 °C. We determined the feasibility, time of implantation, stent deployment and stent fixation., Results: Percutaneous mitral valved stent implantation was successful in all cases. Good handling properties and precise positioning were achieved. Time of implantation was comparable in the fluoroscopic and endoscopic groups at 10:41 ± 3:18 and 10:09 ± 2:42 min, respectively. Apical fixation with the occluder was excellent in all 22 cases., Conclusions: The feasibility of percutaneous mitral valved stent implantation has been demonstrated in preliminary in vitro experiments. Subsequent studies are warranted to determine the efficacy of this minimally invasive catheter-based mitral valved stent implantation., (© The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Objectives: A large cohort of patients suffering from severe mitral regurgitation does not meet the indications for conventional surgery and would greatly benefit from a transcatheter approach in the beating heart. Consequently, off-pump transcatheter mitral valve procedures have been the focus of recent research. The aim of this study was the in vivo evaluation and comparison of subannular versus apical fixation of mitral valved stents to show the feasibility of subannular anchorage., Methods: Twenty-two pigs received a self-expanding valved stent in the mitral position in an off-pump procedure. The first design (design AP: n = 12) was anchored apically and served as the control group. The second design (design SA: n = 10) included additional sub-annular fixation elements. Echocardiographic and haemodynamic evaluations were conducted before and 1 h after stent implantation., Results: Haemodynamic stability was achieved, and the capillary wedge pressure was within a normal range (AP: 11 ± 4 mmHg, SA: 9 ± 4 mmHg). Paravalvular leakages were trace or less in 19 of 20 cases. The mean gradients across the valved stent increased (P ≤ 0.014) but remained within a physiological range in both groups (AP: 1.2 ± 0.6 mmHg, SA: 2.6 ± 2.0 mmHg). The longitudinal heart function remained within a physiological normal range (AP: 0.95 ± 0.1 cm, SA: 0.95 ± 0.1 cm) but was reduced in group SA. The ejection fraction decreased after stent implantation (AP: 52 ± 10%, SA: 48 ± 4%). The mean survival time was higher in group AP compared with group SA., Conclusions: The proof-of-principle for the subannular fixation was shown with haemodynamic stability, low gradients and physiological longitudinal function. A decreased ejection fraction, survival time and fractures identify potential areas for improvement. With regard to the long-term outcome, the group with subannular fixation did not reach the results of the group with apical fixation in this study., (© The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

In this case report, the value of real-time three-dimensional transesophageal echocardiography (TEE) for guidance and assessment of orthotopic tricuspid valved stent implantation in the beating heart is assessed in four pigs. A full two-dimensional TEE evaluation of standardized parameters was conducted. Three-dimensional TEE provided dependable imaging of anatomical structures of the right side of the heart, the delivery system, and the valved stent, allowing easier orientation and more accurate views for the surgical team. Although visualization of the tricuspid valve in the porcine model is challenging, it contributed highly to the successful implantation of the tricuspid valved stent.

Background/objectives: This study presents the recent results of transapical implantation of a new design of a mitral valved stent with up to three months follow-up., Methods: A self-expanding re-designed mitral valved stent was implanted via transapical approach into the beating heart of eight pigs. Echocardiographic- and hemodynamic parameters were assessed before (n=8), at 1h (n=8), at one month (n=6), at two months (n=2), and at three months (n=1) after implantation and a cardiac CT was conducted., Results: The stent was successfully deployed in all animals. Two animals died within the first month due to incorrect fixation force. Echocardiographic evaluation showed low gradients (3.9 ± 1.4 mm Hg and 1.9 ± 0.8 mm Hg across the valved stent and aortic valve) and a normal mitral annular plane systolic excursion (1.1 ± 0.2 cm) after one month. No paravalvular leakages (PVL) were detected after 1h. The pulmonary artery pressure did not increase after valved stent implantation (p ≥ 0.106). The pulmonary capillary wedge pressure (PCWP) slightly increased to 16 ± 3 mm Hg after one month (p=0.033). The left ventricular end-diastolic pressure was mildly elevated (15.8 ± 8.6 mm Hg) after one month., Conclusions: Secure deployment and correct position of the valved stents were reproducibly achieved in the off-pump implantation procedure. No paravalvular leakages after 1h as well as low gradients, few stent fractures and a normal longitudinal function after one month were achieved with this newly developed and well-aligned prototype. However, a number of challenges have been identified during this study and potential for improvement has been identified., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Objectives: Off-pump transcatheter valved stent implantation could be a treatment option for patients suffering from symptomatic tricuspid regurgitation (TR) who are classified as inoperable. In this study, we present our recent short-term results of transventricular tricuspid valved stent implantation and compare different stent types for atrial anchorage., Methods: Fifteen pigs received a self-expandable valved stent implantation off-pump via a transventricular access. Successfully implanted pigs were observed over a period of 6 h (n = 9), 48 h (n = 1) and 4 weeks (n = 1). Haemodynamic and full transoesophageal echocardiographic (TOE) evaluations were done before, 1 h, 3 h (n = 11; all successfully implanted pigs), and 6 h (n = 9; acute group) after implantation. Nine days postimplantation, one pig received additional angiography, computed tomography (CT) and transthoracic echocardiography (TTE). Post-mortem, gross examination was conducted to analyse the stent position and deformation. In two pigs (48 h and 4 weeks survival) histological staining and immunohistochemistry of surrounding myocardium was performed., Results: The heart rate significantly increased in all pigs postimplantation from 66.8 ± 13.6 to 101.8 ± 24.6 bpm, whereas cardiac output and pressure levels remained unchanged. Orthotopic positioning was reproducibly achieved. TOE showed an efficient reduction of paravalvular leakages from a mean grade of 1.4 1 h postimplantation to a mean of 0.9 at 6 h postimplantation due to a special sealing pouch. The ratio early and late ventricular filling velocities remained constant and the valvular gradient across the valved stent stayed low during the observation period. Angiography, CT and TTE confirmed orthotopic positioning and mild grade of paravalvular leakage after 9 days (n = 1). Only mild TR was observed here. The ventricular part of the stent was deformed to an oval shape in 7 of 14 animals as shown via post-mortem examination. The surrounding tissue after 1 month (n = 1) showed normal morphology, without inflammation or calcification., Conclusion: This study shows the feasibility of catheter-based replacement of the tricuspid valve by a valved stent in an off-pump procedure. The successive enhancements in this tricuspid valved stent design lead to a prototype being ready for mid- to long-term evaluations.

Objective: The aim of tissue engineering is, for instance, to create a new valve or organ that is similar to the native one. This new construct may have the capability of growth, repair, and remodeling. One instance where tissue engineering offers an enormous advantage is in the treatment of Tetralogy of Fallot. After repair of this defect, pulmonary valve regurgitation with late ventricular dysfunction is not uncommonly observed., Methods: In this study, we compared the use of endothelial cells (ECs) and smooth muscle cells (SMCs) derived from the carotid artery (group 1/n=5) with CD133+-cells derived from the bone-marrow (group 2/n=5) of juvenile sheep. Western blot analysis and histology were done before and after percutaneous pulmonary valved stent implantation. After seeding of the pulmonary valved stent with one of the cell groups, the construct was placed in a dynamic bioreactor for 16 days. After incubation, the valved stent was seeded again for 3 days. Finally, the valved stent was implanted percutaneously under angiographic control., Results: In group 1, α-actin and calponin were found in the EC and SMC population by using Western blot analysis. In contrast, CD31 was found in EC, but not in the SMC population. Cells from group 2 demonstrated a pure population. CD133+-cells were detected in the CD133+-cell population and no CD133+-cells were found in the negative fraction. Three months after implantation, the transvalvular gradient was significantly higher in group 1 compared to group 2. CD31-staining demonstrated a confluent monolayer in both groups. Immunohistochemistry revealed strong expression of α-smooth-muscle-actin and an in-growth into the leaflets of both groups (p=ns). CD3-, CD20-, CD45-, and CD68-staining confirmed no signs of inflammation in group 2, whereas in group 1 small amounts of inflammation were detected in all analyzed animals. Von Kossa staining revealed mild to moderate calcifications in the annular region of group 1. In contrast, less calcification was detected in group 2., Conclusion: Autologous CD133+-cells derived from bone marrow had a better outcome with regard to calcification, inflammation, and transvalvular gradient compared to autologous cells derived from the carotid artery. Therefore, CD133+-cells are more advantageous for tissue engineering of heart valves.

To date, transcatheter valve implantation is limited to the replacement of pulmonary and aortic valves. The aim of this study was to analyze a valved stent for minimally invasive implantation in the mitral position. A self-expanding mitral valved stent was designed for transapical implantation. Thirty pigs underwent off-pump mitral valved stent implantation with follow-up times of 60 minutes (n = 17) and seven days (n = 13). Transesophageal echocardiography and computed tomography were used to evaluate stent function and positioning. After valved stent deployment, accurate adjustment of the intra-annular position reduced paravalvular leakage in all animals. Accurate positioning was established in all but five animals. The average mean transvalvular gradient across the mitral valve and the left ventricular outflow tract recorded immediately after deployment, six hours and one week were 1.85 ± 0.95 mmHg, 3.45 ± 1.65 mmHg, 4.15 ± 2.3 mmHg and 1.35 ± 1.35 mmHg, 1.45 ± 0.7 mmHg, 1.9 ± 0.65 mmHg, respectively. No valved stent migration, embolization, systolic anterior movement or left ventricular outflow tract obstruction was observed. The mitral valved stent can be deployed in a reproducible manner to achieve reliable stent stability, minimal gradients across the left ventricular outflow tract and adequate stent function in acute and short term experimental settings.

Aims: Percutaneous implantation has already been used clinically and is a great option for treating young patients. The use of autologous tissue-engineered valved stents might solve the problem of degeneration and limited durability of biological heart valves., Methods and Results: Porcine pulmonary heart valves and small intestinal submucosa were obtained from a slaughterhouse. The intestinal submucosa was used to cover the inside of the porcine pulmonary valved stents. Endothelial cells (ECs) and autologous myofibroblasts (MFs) were used from carotid artery segments of juvenile sheep. After MF seeding, constructs were placed in a dynamic bioreactor system and cultured for 16 days. After additional EC seeding, tissue-engineered valved stents were percutaneously deployed into the annulus of the pulmonary valve (n = 9). Angiography was performed at implantation and 4-week follow-up. Constructs were analysed radiographically, by post-mortem examination, and microscopically. In all but one case, orthotopic positioning of the stents (n = 6) at the time of implantation and explantation was observed angiographically, macroscopically, and by computer tomography scan and demonstrated normal valve function (n = 7). Gross morphology confirmed excellent opening and closure characteristics of all leaflets after 4 weeks (n = 7). Strong expression of α-smooth muscle actin in neo-interstitial cells and of von Willebrand factor and PECAM-1 in ECs was revealed by immunocytochemistry., Conclusion: Good functioning and morphological characteristics were observed after percutaneous tissue-engineered valved stent implantation with autologous cells. This implantation of autologous tissue-engineered valved stents will become a valid future option in adolescents.

Objective: To date, transfemoral and trans-apical valved stent implantation techniques are limited to the replacement of pulmonary and aortic valves in a strictly selected group of patients. The current study was designed to assess the short-term follow-up using a mitral valved stent in off-pump technique., Methods: A self-expanding, repositionable mitral valved stent was created for trans-apical implantation. Five pigs underwent successful trans-catheter implantation. Data were gathered to assess the animals' haemodynamical stability after stent implantation (n=5), 6h (n=5) and 1 week (n=4). The valved stent function was assessed by trans-oesophageal echocardiography and ventriculogram. Cardiac computed tomography (CT) was used to evaluate positioning of the new implant., Results: Precise valved stent deployment and accurate subsequent adjustment of its intra-annular position allowed for reduction of paravalvular leakage in all animals. The deployment time ranged from 122 to 271 s and blood loss from 65 to 245 cc. Accurate positioning was established in all but one animal. The average mean transvalvular gradient and mean gradient across left ventricular outflow tract (LVOT) recorded immediately after deployment, 6 h and 1 week were 1.9 + or - 0.9 mmHg, 3.5 + or - 1.6 mmHg, 4.1 + or - 02.3 mmHg and 1.4 + or - 01.3 mmHg, 1.5 + or - 0.7 mmHg 1.9 + or - 0.7 mmHg, respectively. Mild regurgitation was present after valved stent deployment in one out of five animals after 1h, one out of five animals at 6h, and two out of four animals at 1 week. All animals exhibited normal haemodynamics after mitral valved stent implantation and maintained stability for the period of monitoring (6h). One animal died of unrecognised imperfect valved stent positioning after 1 day. In the subsequent animals, valved stent migration, embolisation, systolic anterior movement or LVOT obstruction was not observed after 1 week follow-up., Conclusions: The new mitral valved stent can be deployed in a reproducible manner to achieve reliable stent stability, minimal gradients across the LVOT and adequate valved stent function in short-term follow-up., (Copyright 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.)

Objectives: Transfemoral application of pulmonary heart valves has been studied for the past 10 years. Nevertheless, size restriction of percutaneous heart valved stents is still imminent., Methods: In this study we implanted percutaneously a novel, low-profile polyurethane valved stent. Percutaneous implantation in pulmonary position was evaluated in 7 sheep. The new valved stent fits into a 14F delivery device. The self-expanding nitinol stent was produced by using a dip-coating technique, and a modified commercially available endovascular stent graft system served as a delivery device. The valved stents were deployed directly over the native pulmonary valve under fluoroscopic control. Transthoracic echocardiography was performed after 4 weeks. At the time of explantation, the animals were reanalyzed and killed. Angiography was performed at implantation and at the end of the study. Explanted constructs were analyzed macroscopically and microscopically., Results: Angiography and echocardiography in all animals demonstrated orthotopic position of the stents at the time of implantation and after 4 weeks. During the deployment procedure, rhythm disturbances occurred in all animals. The peak-to-peak transvalvular gradient was 2.3 +/- 1.2 mm Hg initially and 4.1 +/- 2.4 mm Hg at follow-up. One-month follow-up confirmed competent neovalves without any paravalvular leakage. Gross morphology demonstrated good opening and closure characteristics. No calcification was seen macroscopically, and surrounding tissue was free of calcification., Conclusion: In the present study we demonstrated successful merging of 2 novel technologies for percutaneous treatment of pulmonary valve diseases using polyurethane stent valve constructs., (Copyright 2010 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Background: Transcatheter aortic and pulmonary valve replacement is currently being tested in human trials. Efforts to create a valved stent to replace the atrioventricular valves have shown limited success. This is due to their their complex anatomy and function., Methods: A self-expanding valved stent was created for transapical replacement of the atrioventricular valve. Ten pigs underwent transapical off-pump mitral valved stent implantation. Data were gathered to assess the animals' hemodynamic stability for 60 minutes after implantation. The valved stent function was assessed by transesophageal echocardiography (TEE) and contrast left ventriculogram., Results: All animals exhibited normal hemodynamics immediately after mitral valved stent implantation and maintained stability for the entire period of monitoring. Accurate positioning of the valved stent was established in all animals. Mild paravalvular regurgitation was found in three out of ten animals by TEE and in two animals during left ventriculogram. No left ventricular outflow tract obstruction was encountered., Conclusions: Transapical off-pump mitral valved stent implantation is feasible in an acute experimental setting. Long-term function of the new valved stent remains to be established.

Introduction: Percutaneous techniques to replace the pulmonary valve are emerging as an alternative to congenital cardiac surgical procedures. Promising experimental and early clinical results have been reported so far, focusing on technical feasibility and valved stent function. The present study aimed to describe the micropathology after experimental percutaneous valve replacement., Methods: Self-expanding nitinol stents carrying a valved bovine jugular vein were transfemorally implanted into the pulmonary position of nine sheep. After 3 months of survival, macro- and micropathological examinations were carried out using standard staining techniques and immunohistochemistry. Additionally, calcification characteristics were determined by X-ray examinations and von Kossa stainings., Results: Six of nine animals survived the 3-month study time with good angiographic and echocardiographic function. All valves were grossly functional at the time of explantation. Slight fibrous overgrowth was seen at the inflow portions of two valved stents. No cuspal perforations or intracuspal hematomas were observed. Light microscopy proved the absence of cellular inflammatory infiltrates in any tissue samples. The myocardium directly proximal to the stent appeared structurally normal without calcification. The overall structure of the native pulmonary artery was well preserved with few mineral deposits spread diffusely throughout the wall distal to the stent. Massive calcification appeared in the bovine jugular-vein wall together with increased numbers of T lymphocytes. Neither calcific deposits in the cusps nor extrinsic mineralization was noted., Conclusion: For the first time, micropathologic evaluation of percutaneously implanted heart valves is described. The results demonstrate that calcification of valved stents occurs in the wall portions without affecting the cusps. The cardiac structures in the vicinity had normal histology without inflammation.

Purpose: To analyze our experience with endovascular stent-grafting of descending aortic aneurysms in high-risk patients., Methods: Nineteen patients underwent endovascular stent-graft repair of descending aortic aneurysms using the Talent Stent Graft System (Medtronic). All patients were considered high-risk for open surgical repair due to their age, requirement for emergency surgery, and comorbidities. Computed tomography and/or MR tomography were performed at 3, 6 and 12 months postoperatively and thereafter every 12 months., Results: Secondary technical success was 100%. Thirty-day mortality was 5%. Incidence of postoperative stroke and paraplegia were 5% each. One patient required a second stent-graft due to a type I endoleak during the same hospital stay (primary technical success 95%). All patients have been followed for a median of 20 months. No migration, wire fractures or endoleak appeared during follow-up., Conclusion: Endovascular stent-grafting had a low 30-day mortality and morbidity in high-risk patients. One patient developed an aortoesophageal fistula 40 days after stent implantation. Stent-graft repair is a valuable supplement to surgical therapy in high-risk patients.

Purpose: In a recent study our group established an acute animal model of percutaneous pulmonary valve replacement using self-expanding nitinol stents. The present study was performed to evaluate these valved stents over a 3-month period., Description: Bovine jugular xenografts were sutured into nitinol stents. Transfemoral implantation in the pulmonary position using a modified commercially available application device (with a 22-French outer diameter) was evaluated in 9 sheep., Evaluation: Two sheep died shortly after successful valved stent implantation due to internal venous hemorrhage. Another 1 sheep died 2.5 months after the procedure due to vegetations on the neovalve leading to subtotal stenosis. All other animals survived the 3-month study time (n = 6). An orthotopic pulmonary valved stent position was achieved in 4 animals and a supravalvular position in 1. During the deployment procedure, rhythm disturbances occurred in all animals, and mean arterial blood pressure dropped from 83.9 +/- 26.0 mm Hg to 68.3 +/- 22.3 mm Hg (p = 0.006) (n = 5). The peak-to-peak transvalvular gradient was 5.1 +/- 4.0 mm Hg initially (n = 5), and 3.6 +/- 1.6 mm Hg at follow-up (n = 5). Three-month angiographic and echocardiographic follow-up confirmed competent neovalves without paravalvular leakages., Conclusions: After 3 months of implantation, percutaneously implanted memory nitinol valved stents demonstrated good function in the sheep.

Purpose: To compare the clinical outcomes of open surgery versus endovascular repair in patients with pathologies of the descending thoracic aorta (DTA)., Methods: This retrospective study included 44 patients (28 men; mean age 68+/-12 years, range 37-86) treated for DTA pathologies between 1995 and 2003. Twenty-two patients (15 men; mean age 68+/-13 years, range 37-86) undergoing stent-graft implantation were matched for sex, age, emergency operation, and comorbidities (coronary artery disease, chronic obstructive pulmonary disease) with a 22-patient contemporaneous surgical cohort (13 men; mean age 69+/-11 years, range 41-80)., Results: Thirty-day mortality was 5% in the stent-graft group and 27% in the open surgery group (p=0.047). The incidences of postoperative stroke and paraplegia were both 5% in the stent-graft group and 9%, respectively, in the open surgery cohort. One patient required a second stent-graft due to an endoleak during the same hospital stay, and 2 reoperations were performed in the standard operation group (p = NS). Lengths of stay in the intensive care unit (ICU) and hospital were 4.3+/-5.4 and 11.9+/-15.0 days, respectively, in the stent-graft group and 10.0+/-7.4 and 21.5+/-17.4 days, respectively, in the open surgery group (p<0.006)., Conclusions: Stent-graft repair was associated with lower 30-day mortality and comparable complication rates in older patients with significant comorbidities and a high percentage of emergency operations compared to open surgery. Stent-graft implantation shortens ICU and hospital stays significantly. In the future, subgroups of patients who may experience the greatest benefit from stent-graft repair in the long term should be defined.

Rationale and Objectives: To evaluate endothelial cell (EC) attachment on different stents and stent-grafts combined with different coating materials., Materials and Methods: Three segments (approximately 1cm(2) each) of Cragg-, Memotherm-, Palmaz-, Strecker-, and Wall-stents, uncovered or covered with polytetrafluoroethylene (PTFE), polyurethane (PU) or polyester (Dacron) were precoated with fibronectin and seeded in vitro under steady conditions with 2 x 10(5) human venous EC/cm(2) for 2 days. EC attachment and morphology was assessed by scanning electron microscopy., Results: Superior EC attachment on uncovered stents was seen on Memotherm-, Palmaz-, and Wall-stent. On uncovered Cragg- and Strecker-stent only a few single and rounded EC could be detected. PTFE-covering lead to an equal or decreased EC coverage in comparison with the uncovered prostheses. An increase in EC coverage on PU-covered stents was seen and on polyester covered stents as compared with uncovered stents., Conclusion: In vitro, EC attachment is clearly different on vascular stents and stent-grafts, probably depending on the material of the stents stent and unknown manufacturing related components. When EC adhesion is desired and stent covering is used, the choice of covering material may influence EC adhesion.

The article presents the European Society of Cardiology/European Association for Cardio-Thoracic Surgery (ESC/EASC) guidelines on myocardial revascularization therapy post-SYNTAX. Featured in the guidelines are the approach to calculate the SYNTAX score and the risk models to assess outcomes as well as the multidisciplinary decision pathways and timing of intervention in coronary artery disease (CAD). Also offered are the recommendations and strategies for diagnosis and treatment of CAD.