Percutaneous and Minimally Invasive Valve Procedures

Improved Geometry of Decellularized Tissue Engineered Heart Valves to Prevent Leaflet Retraction

Recent studies on decellularized tissue engineered heart valves (DTEHVs) showed rapid host cell repopulation and increased valvular insufficiency developing over time, associated with leaflet shortening. A possible explanation for this result was found using computational simulations, which revealed radial leaflet compression in the original valvular geometry when subjected to physiological pressure conditions. Therefore, an improved geometry was suggested to enable radial leaflet extension to counteract for host cell mediated retraction. In this study, we propose a solution to impose this new geometry by using a constraining bioreactor insert during culture. Human cell based DTEHVs (n = 5) were produced as such, resulting in an enlarged coaptation area and profound belly curvature. Extracellular matrix was homogeneously distributed, with circumferential collagen alignment in the coaptation region and global tissue anisotropy. Based on in vitro functionality experiments, these DTEHVs showed competent hydrodynamic functionality under physiological pulmonary conditions and were fatigue resistant, with stable functionality up to 16 weeks in vivo simulation. Based on implemented mechanical data, our computational models revealed a considerable decrease in radial tissue compression with the obtained geometrical adjustments. Therefore, these improved DTEHV are expected to be less prone to host cell mediated leaflet retraction and will remain competent after implantation.

Hemodynamic changes following aortic valve bypass: a mathematical approach

Aortic valve bypass (AVB) has been shown to be a viable solution for patients with severe aortic stenosis (AS). Under this circumstance, the left ventricle (LV) has a double outlet. The objective was to develop a mathematical model capable of evaluating the hemodynamic performance following the AVB surgery. A mathematical model that captures the interaction between LV, AS, arterial system, and AVB was developed. This model uses a limited number of parameters that all can be non-invasively measured using patient data. The model was validated using in vivo data from the literature. The model was used to determine the effect of different AVB and AS configurations on flow proportion and pressure of the aortic valve and the AVB. Results showed that the AVB leads to a significant reduction in transvalvular pressure gradient. The percentage of flow through the AVB can range from 55.47% to 69.43% following AVB with a severe AS. LV stroke work was also significantly reduced following the AVB surgery and reached a value of around 1.2 J for several AS severities. Findings of this study suggest: 1) the AVB leads to a significant reduction in transvalvular pressure gradients; 2) flow distribution between the AS and the AVB is significantly affected by the conduit valve size; 3) the AVB leads to a significant reduction in LV stroke work; and 4) hemodynamic performance variations can be estimated using the model.

Minimally invasive primary aortic valve surgery: the OLV Aalst experience

BACKGROUND

The purpose of this study was to evaluate our in-hospital outcomes with primary J-sternotomy aortic valve surgery since the initiation of our program in 1997.

METHODS

Between October 1(st) 1997 and August 31(st) 2014, 768 patients (mean age: 69.1±11.2 years, 46.6% females, 15.6% aged greater than 80 years) underwent primary JS-AVS. Additional risk factors included diabetes mellitus (n=98, 12.2%), peripheral vascular disease (n=42, 5.5%) and body mass index greater than 30 (n=144, 18.8%). The mean logistical EuroSCORE I was 5.46%±4.5%.

RESULTS

Aortic valve replacement and repair were performed in 758 (98.7%) and 10 (1.3%) patients respectively, for isolated valve stenosis (n=472, 61.8%), incompetence (n=56, 7.3%) and mixed valve disease (n=236, 30.9%). Valve pathology included sclerosis (n=516, 67.2%), rheumatic disease (n=110, 14.3%) and endocarditis (n=10, 1.3%). Reasons for conversion to full sternotomy (n=23, 3.0%) included porcelain ascending aorta (n=3, 0.4%), inadequate visualization (n=2, 0.3%) and intra-operative complications (n=18, 2.3%). Mean length of hospital stay was 11.0±7.4 days. Morbidity included stroke (n=15, 2.0%), revision or re-exploration (n=52, 6.8%), atrial fibrillation (n=201, 26.2%) and sternitis (n=5, 0.7%). In-hospital mortality was 1.6% (n=12). Overall survival at 30 days was 98.0%.

CONCLUSIONS

JS-AVS is safe and is our routine approach for isolated aortic valve disease. Procedure related mortality is lower than predicted, conversion rates limited and significant morbidity minimal.

Minimally invasive aortic valve surgery: state of the art and future directions

Minimally invasive aortic valve replacement (MIAVR) is defined as an aortic valve replacement (AVR) procedure that involves a small chest wall incision as opposed to conventional full sternotomy (FS). The MIAVR approach is increasingly being used with the aim of reducing the "invasiveness" of the surgical procedure, while maintaining the same efficacy, quality and safety of a conventional approach. The most common MIAVR techniques are ministernotomy (MS) and right anterior minithoracotomy (RT) approaches. Compared with conventional surgery, MIAVR has been shown to reduce postoperative mortality and morbidity, providing faster recovery, shorter hospital stay and better cosmetics results, requires less rehabilitations resources and consequently cost reduction. Despite these advantages, MIAVR is limited by the longer cross-clamp and cardiopulmonary bypass (CPB) times, which have raised some concerns in fragile and high risk patients. However, with the introduction of sutureless and fast deployment valves, operative times have dramatically reduced by 35-40%, standardizing this procedure. According to these results, the MIAVR approach using sutureless valves may be the "real alternative" to the transcatheter aortic valve implantation (TAVI) procedures in high risk patients "operable" patients. Prospective randomized trials are required to confirm this hypothesis.

Review of Minimally Invasive Aortic Valve Surgery

Minimally invasive aortic valve surgery (MIAVS) has been developed for the last 20 years. The improvements in techniques have permitted cardiac surgeons to perform aortic valve replacement safely and efficiently with minimally incisions. Patients have become older and have multiple comorbidities and this is expected to grow in number. Less-invasive procedures are known to reduce the number of complications, together with smaller incisions, less pain, less blood loss and reduced length of hospital stay. Selective preoperative planning with computed tomography is key to the pre-investigation stage. Hybrid and staged procedures with interventional cardiologists are part of the armamentarium and may be appealing for the present and near future. Despite the nature of demanding procedures and longer learning curve with increased cardiopulmonary bypass times, the outcomes are comparable with same quality as conventional open surgery. Patient recovery is the ultimate purpose of these approaches.

Medical devices early assessment methods: systematic literature review

OBJECTIVES

The aim of this study was to get an overview of current theory and practice in early assessments of medical devices, and to identify aims and uses of early assessment methods used in practice.

METHODS

A systematic literature review was conducted in September 2013, using computerized databases (PubMed, Science Direct, and Scopus), and references list search. Selected articles were categorized based on their type, objective, and main target audience. The methods used in the application studies were extracted and mapped throughout the early stages of development and for their particular aims.

RESULTS

Of 1,961 articles identified, eighty-three studies passed the inclusion criteria, and thirty were included by searching reference lists. There were thirty-one theoretical papers, and eighty-two application papers included. Most studies investigated potential applications/possible improvement of medical devices, developed early assessment framework or included stakeholder perspective in early development stages. Among multiple qualitative and quantitative methods identified, only few were used more than once. The methods aim to inform strategic considerations (e.g., literature review), economic evaluation (e.g., cost-effectiveness analysis), and clinical effectiveness (e.g., clinical trials). Medical devices were often in the prototype product development stage, and the results were usually aimed at informing manufacturers.

CONCLUSIONS

This study showed converging aims yet widely diverging methods for early assessment during medical device development. For early assessment to become an integral part of activities in the development of medical devices, methods need to be clarified and standardized, and the aims and value of assessment itself must be demonstrated to the main stakeholders for assuring effective and efficient medical device development.

First clinical trial of a self-expandable transcatheter heart valve in Japan in patients with symptomatic severe aortic stenosis

BACKGROUND

Transcatheter aortic valve implantation (TAVI) may be a viable solution for inoperable or high-risk patients with aortic stenosis (AS), providing the benefit of valve replacement without the associated risks of surgery.

METHODS AND RESULTS

The prospective, multicenter MDT-2111 Japan Trial evaluated the efficacy and safety of a self-expandable TAV in patients with severe AS. A total of 55 patients were enrolled (October 2011 to October 2012). Mean age was 82.5±5.5 years; 30.9% male, 100% NYHA III/IV, and STS 8.0±4.2%. At 6 months, 91.7% of the iliofemoral patients had met the primary endpoint (an improvement of at least 1 NYHA class and an effective orifice area >1.2 cm(2) for iliofemoral patients). For all patients, freedom from all-cause mortality at 6 months was 90.8%. At 30 days, the Kaplan-Meier rate of major vascular complications was 10.9%, the rate of permanent pacemaker implantation was 22.2% and the rate of major stroke was 3.7%. The incidences of paravalvular regurgitation for all implanted patients at 6 months were: 38.3% (none), 25.5% (trace), 31.9% (mild), 4.3% (moderate), and 0.0% (severe).

CONCLUSIONS

This is the first study to evaluate a self-expandable TAV in a Japanese patient population. The data show successful achievement of the study's primary objective and demonstrate the functional and anatomical effectiveness of the MDT-2111 TAV system.

Barlow's mitral valve disease: results of conventional and minimally invasive repair approaches

Barlow's valve is a clinically important form of degenerative mitral valve (MV) disease that is characterized by unique clinical, echocardiographic and pathological features. Successful and durable repair of Barlow's MV represents a clinical challenge for most cardiac surgeons. An armamentarium of different MV repair techniques may be required, resectional, neochordal or plicational techniques. Although conventional sternotomy remains the mainstay approach for MV surgery in the majority of cardiac surgery centers, minimally invasive surgery (MIS) is becoming increasingly accepted amongst patients, referring physicians and practicing cardiac surgeons. As surgical approaches, instrumentation and operative experience develop, select centers are now performing MIS MV surgery for nearly all MV patients. Although successful Barlow's MV repair is more complex than that for most degenerative pathologies, several centers have published relatively large series of MIS MV repair for Barlow's disease. In this review article, we highlight and compare the early and long-term results of conventional and minimally invasive approaches to Barlow's and bileaflet mitral prolapse disease. Recent studies from various large volume centers around the world have demonstrated equivalent safety and efficacy outcomes of the MIS approach compared to conventional sternotomy surgery. In addition, MIS MV surgery may allow patients to benefit from a cosmetically appealing incision, a faster recovery and a quicker return to normal activities. However, a definite learning curve has been demonstrated for MIS MV surgery. If a patient with Barlow's disease or other complex MV pathology desires to undergo MIS MV surgery, referral to a center and/or surgeon with extensive experience in MIS MV surgery is recommended.

Transcatheter implantation of homologous "off-the-shelf" tissue-engineered heart valves with self-repair capacity: long-term functionality and rapid in vivo remodeling in sheep

OBJECTIVES

This study sought to evaluate long-term in vivo functionality, host cell repopulation, and remodeling of "off-the-shelf" tissue engineered transcatheter homologous heart valves.

BACKGROUND

Transcatheter valve implantation has emerged as a valid alternative to conventional surgery, in particular for elderly high-risk patients. However, currently used bioprosthetic transcatheter valves are prone to progressive dysfunctional degeneration, limiting their use in younger patients. To overcome these limitations, the concept of tissue engineered heart valves with self-repair capacity has been introduced as next-generation technology.

METHODS

In vivo functionality, host cell repopulation, and matrix remodeling of homologous transcatheter tissue-engineered heart valves (TEHVs) was evaluated up to 24 weeks as pulmonary valve replacements (transapical access) in sheep (n = 12). As a control, tissue composition and structure were analyzed in identical not implanted TEHVs (n = 5).

RESULTS

Transcatheter implantation was successful in all animals. Valve functionality was excellent displaying sufficient leaflet motion and coaptation with only minor paravalvular leakage in some animals. Mild central regurgitation was detected after 8 weeks, increasing to moderate after 24 weeks, correlating to a compromised leaflet coaptation. Mean and peak transvalvular pressure gradients were 4.4 ± 1.6 mm Hg and 9.7 ± 3.0 mm Hg, respectively. Significant matrix remodeling was observed in the entire valve and corresponded with the rate of host cell repopulation.

CONCLUSIONS

For the first time, the feasibility and long-term functionality of transcatheter-based homologous off-the-shelf tissue engineered heart valves are demonstrated in a relevant pre-clinical model. Such engineered heart valves may represent an interesting alternative to current prostheses because of their rapid cellular repopulation, tissue remodeling, and therewith self-repair capacity. The concept of homologous off-the-shelf tissue engineered heart valves may therefore substantially simplify previous tissue engineering concepts toward clinical translation.

Transcatheter aortic valve implantation: status and challenges

Calcific aortic valve disease of the elderly is the most prevalent hemodynamically-significant valvular disease, and the most common lesion requiring valve replacement in industrialized countries. Transcatheter aortic valve implantation is a less invasive alternative to classical aortic valve replacement that can provide a therapeutic option for high-risk or inoperable patients with aortic stenosis. These devices must be biocompatible, have excellent hemodynamic performance, be easy to insert, be securely anchored without sutures, and be durable, without increased risk of thrombosis or infection. To date, complications are related to the site of entry for insertion, the site of implantation (aorta, coronary ostia, base of left ventricle), and to the structure and design of the inserted device. However, as with any novel technology unanticipated complications will develop. Goals for future development will be to make the devices more effective, more durable, safer, and easier to implant, so as to further improve outcome for patients with severe aortic stenosis. The pathologist participating in research and development, and examination of excised devices will have a critical role in improving outcome for these patients.

Polymeric trileaflet prosthetic heart valves: evolution and path to clinical reality

Present prosthetic heart valves, while hemodynamically effective, remain limited by progressive structural deterioration of tissue valves or the burden of chronic anticoagulation for mechanical valves. An idealized valve prosthesis would eliminate these limitations. Polymeric heart valves (PHVs), fabricated from advanced polymeric materials, offer the potential of durability and hemocompatibility. Unfortunately, the clinical realization of PHVs to date has been hampered by findings of in vivo calcification, degradation and thrombosis. Here, the authors review the evolution of PHVs, evaluate the state of the art of this technology and propose a pathway towards clinical reality. In particular, the authors discuss the development of a novel aortic PHV that may be deployed via transcatheter implantation, as well as its optimization via device thrombogenicity emulation.

Matrix production and organization by endothelial colony forming cells in mechanically strained engineered tissue constructs

Aims

Tissue engineering is an innovative method to restore cardiovascular tissue function by implanting either an in vitro cultured tissue or a degradable, mechanically functional scaffold that gradually transforms into a living neo-tissue by recruiting tissue forming cells at the site of implantation. Circulating endothelial colony forming cells (ECFCs) are capable of differentiating into endothelial cells as well as a mesenchymal ECM-producing phenotype, undergoing Endothelial-to-Mesenchymal-transition (EndoMT). We investigated the potential of ECFCs to produce and organize ECM under the influence of static and cyclic mechanical strain, as well as stimulation with transforming growth factor β1 (TGFβ1).

Methods and Results

A fibrin-based 3D tissue model was used to simulate neo-tissue formation. Extracellular matrix organization was monitored using confocal laser-scanning microscopy. ECFCs produced collagen and also elastin, but did not form an organized matrix, except when cultured with TGFβ1 under static strain. Here, collagen was aligned more parallel to the strain direction, similar to Human Vena Saphena Cell-seeded controls. Priming ECFC with TGFβ1 before exposing them to strain led to more homogenous matrix production.

Conclusions

Biochemical and mechanical cues can induce extracellular matrix formation by ECFCs in tissue models that mimic early tissue formation. Our findings suggest that priming with bioactives may be required to optimize neo-tissue development with ECFCs and has important consequences for the timing of stimuli applied to scaffold designs for both in vitro and in situ cardiovascular tissue engineering. The results obtained with ECFCs differ from those obtained with other cell sources, such as vena saphena-derived myofibroblasts, underlining the need for experimental models like ours to test novel cell sources for cardiovascular tissue engineering.

In vitro evaluation of a novel hemodynamically optimized trileaflet polymeric prosthetic heart valve

Calcific aortic valve disease is the most common and life threatening form of valvular heart disease, characterized by stenosis and regurgitation, which is currently treated at the symptomatic end-stages via open-heart surgical replacement of the diseased valve with, typically, either a xenograft tissue valve or a pyrolytic carbon mechanical heart valve. These options offer the clinician a choice between structural valve deterioration and chronic anticoagulant therapy, respectively, effectively replacing one disease with another. Polymeric prosthetic heart valves (PHV) offer the promise of reducing or eliminating these complications, and they may be better suited for the new transcatheter aortic valve replacement (TAVR) procedure, which currently utilizes tissue valves. New evidence indicates that the latter may incur damage during implantation. Polymer PHVs may also be incorporated into pulsatile circulatory support devices such as total artificial heart and ventricular assist devices that currently employ mechanical PHVs. Development of polymer PHVs, however, has been slow due to the lack of sufficiently durable and biocompatible polymers. We have designed a new trileaflet polymer PHV for surgical implantation employing a novel polymer-xSIBS-that offers superior bio-stability and durability. The design of this polymer PHV was optimized for reduced stresses, improved hemodynamic performance, and reduced thrombogenicity using our device thrombogenicity emulation (DTE) methodology, the results of which have been published separately. Here we present our new design, prototype fabrication methods, hydrodynamics performance testing, and platelet activation measurements performed in the optimized valve prototype and compare it to the performance of a gold standard tissue valve. The hydrodynamic performance of the two valves was comparable in all measures, with a certain advantage to our valve during regurgitation. There was no significant difference between the platelet activation rates of our polymer valve and the tissue valve, indicating that similar to the latter, its recipients may not require anticoagulation. This work proves the feasibility of our optimized polymer PHV design and brings polymeric valves closer to clinical viability.

Predictors of one-year mortality after transcatheter aortic valve implantation for severe symptomatic aortic stenosis

Transcatheter aortic valve implantation (TAVI) is already an accepted option to treat elderly patients with severe symptomatic aortic stenosis who are inoperable or at high surgical risk. However, short- and long-term mortality after TAVI remains an important issue, raising the need to further improve the technology of TAVI as well as to identify patients who will not benefit from TAVI. A total of 1,391 patients treated with TAVI at 27 hospitals were included in the German Transcatheter Aortic Valve Interventions - Registry. One-year follow-up data were available for 1,318 patients (94.8%), with a mean follow-up period of 12.9 ± 4.5 months. One-year mortality was 19.9%. Survivors and nonsurvivors showed multiple differences in patient characteristics, indications for interventions, preintervention and interventional characteristics, and postintervention events. A higher logistic European System for Cardiac Operative Risk Evaluation score was associated with higher 1-year mortality (p <0.0001). Cox proportional-hazards analysis revealed the following independent predictors of mortality: among preintervention findings: previous mitral insufficiency ≥II° (p = 0.0005), low-gradient aortic stenosis (p = 0.0008), previous decompensation (p = 0.0061), previous myocardial infarction (p = 0.0138), renal failure (p = 0.0180), previous New York Heart Association class IV (p = 0.0254), and female gender (p = 0.0346); among procedural factors: intraprocedural conversion to surgery (p = 0.0009), peri-intervention stroke (p = 0.0003), and residual aortic insufficiency ≥II° (p = 0.0022); and among postprocedural events: postintervention myocardial infarction (p = 0.0009) and postintervention pulmonary embolism (p = 0.0025). In conclusion, 1-year mortality after TAVI was 19.9% in this series. Patient characteristics and procedural as well as postintervention factors associated with mortality were identified, which may allow better patient selection and better care for these critically ill patients.

Impact of aortic valve calcification severity and impaired left ventricular function on 3-year results of patients undergoing transcatheter aortic valve replacement

OBJECTIVES

To evaluate clinical pre-interventional predictors of 3-year outcome and mortality in high-risk patients with severe aortic valve stenosis treated with transcatheter aortic valve implantation (TAVI).

METHODS

Among 367 patients included in the Aachen TAVI registry, 76 patients with baseline dual-source computed tomography (DSCT) for the quantification of aortic valve calcification (AVC) and a 3-year follow-up were identified.

RESULTS

Survival at 30 days was 91 %, and it was 75 %, 66 % and 64 % at 1, 2 years and 3 years, respectively. Non-survivors at 3 years showed a significantly higher Agatston AVC score (2,854 ± 1,651) than survivors (1,854 ± 961, P = 0.007). Multivariate analysis including age, logistic EuroScore, glomerular filtration rate, Agatston AVC score, ejection fraction < 40 %, NYHA class, baseline medication, chronic lung disease and aortic regurgitation revealed that only the Agatston AVC score (P = 0.03) and impaired left ventricular function (P = 0.001) was significantly associated with mortality. Patients with Agatston AVC scores >2,000 had a significantly lower 3-year survival rate compared with patients with scores <2,000 (47 % vs 79 %, P = 0.004).

CONCLUSIONS

In patients referred for TAVI, aortic valve calcification severity and impaired left ventricular function may serve as a predictor of long-term mortality. Therefore, AVC scores easily determined from pre-procedural CT datasets may be used for patient risk stratification.

Toward optimization of a novel trileaflet polymeric prosthetic heart valve via device thrombogenicity emulation

Aortic stenosis is the most prevalent and life-threatening form of valvular heart disease. It is primarily treated via open-heart surgical valve replacement with either a tissue or a mechanical prosthetic heart valve (PHV), each prone to degradation and thrombosis, respectively. Polymeric PHVs may be optimized to eliminate these complications, and they may be more suitable for the new transcatheter aortic valve replacement procedure and in devices like the total artificial heart. However, the development of polymer PHVs has been hampered by persistent in vivo calcification, degradation, and thrombosis. To address these issues, we have developed a novel surgically implantable polymer PHV composed of a new thermoset polyolefin called cross-linked poly(styrene-block-isobutylene-block-styrene), or xSIBS, in which key parameters were optimized for superior functionality via our device thrombogenicity emulation methodology. In this parametric study, we compared our homogeneous optimized polcymer PHV to a prior composite polymer PHV and to a benchmark tissue valve. Our results show significantly improved hemodynamics and reduced thrombogenicity in the optimized polymer PHV compared to the other valves. These results indicate that our new design may not require anticoagulants and may be more durable than its predecessor, and validate the improvement, toward optimization, of this novel polymeric PHV design.

Posterior ventricular anchoring neochordal repair of degenerative mitral regurgitation efficiently remodels and repositions posterior leaflet prolapse

OBJECTIVES

Mitral valve repair techniques for degenerative disease typically entail leaflet resection or neochordal construction, which may require extensive resection, leaflet detachment/reattachment, reliance on diseased native chords or precise neochordal measuring. Occasionally, impaired leaflet mobility, reduced coaptation surface and systolic anterior motion (SAM) may result. We describe a novel technique for addressing posterior leaflet prolapse/flail, which both simplifies repair and addresses these issues.

METHODS

Fifty-four patients (age 62 ± 11 years) with degenerative MR underwent this new repair, 36 of whom minimally-invasively. A CV5 Gore-Tex suture was placed into the posterior left ventricular myocardium underneath the prolapsing segment as an anchor. This suture was then used to imbricate a portion of the prolapsed segment into the ventricle, creating a smooth, broad, non-prolapsed coapting surface on a leaflet with preserved mobility, additional neochordal support and posteriorly positioned enough to preclude SAM.

RESULTS

Repair was successful in all patients. The mean MR grade was reduced from +3.8 to +0.1 with 50 of 54 patients having zero MR and 4 of the 54 having trace or mild MR. All patients had proper antero-posterior location of the coaptation line of a mean length of 10.2 mm, and preserved posterior leaflet mobility. No patients had SAM or mitral stenosis. All patients were discharged and are currently doing well.

CONCLUSION

This new technique facilitated efficient single-suture repair of the prolapsed posterior leaflet mitral regurgitation without the need for resection or sliding annuloplasty. It precluded the need for precise neochordal measurement and preserved the leaflet coaptation surface.

Transcatheter aortic valve implantation in patients with "porcelain" aorta (from a Multicenter Real World Registry)

The presence of severe atherosclerosis of the ascending aorta, and its extreme form the "porcelain" aorta, is associated with a worse clinical outcome in patients undergoing surgical aortic valve replacement. Percutaneous transcatheter aortic valve implantation (TAVI) for severe symptomatic aortic stenosis can overcome this problem: 1,374 TAVI procedures were performed at 27 hospitals in 147 patients (10.7%) with and 1,227 (89.3%) without a porcelain aorta. The mean reported prevalence of a porcelain aorta at the hospitals was 7.8% ± 14.8% (range 0% to 70%). Diabetes mellitus (46.3% vs 33.2%, p = 0.00018), chronic obstructive pulmonary disease (43.5% vs 22.2%, p <0.0001), and peripheral arterial obstructive disease (34.7% vs 20.0%, p <0.0001) were more prevalent in patients with a porcelain aorta. In patients with a porcelain aorta, coronary ischemia occurred more often (2.0% vs 0.1%, p <0.0001), with a tendency toward a greater stroke rate (5.5% vs 2.8%, p = 0.08), greater in-hospital death rate (10.9% vs 8.1%, p = 0.24), and greater death or stroke rate (14.4% vs 10.2%, p = 0.12). On multivariate analysis, the presence of a porcelain aorta was not associated with in-hospital death (odds ratio 1.36, 95% confidence interval 0.72 to 2.55, p = 0.3441) nor in-hospital death or stroke (odds ratio 1.50, 95% confidence interval 0.81 to 2.47, p = 0.2207). In conclusion, in this real-world TAVI registry, a "porcelain" aorta was diagnosed in almost every tenth patient. Although differences were found in its frequency among the participating hospitals, the presence of a porcelain aorta was not associated with in-hospital death or stroke.

Transcatheter aortic valve implantation: recommendations for practice based on a multidisciplinary review including cost-effectiveness and ethical and organizational issues

Transcatheter aortic valve implantation (TAVI) is a relatively new technology for the treatment of severe and symptomatic aortic valve stenosis. TAVI offers an alternative therapy for patients unable to be treated surgically because of contraindications or severe comorbidities. It is being rapidly dispersed in Canada, as it is worldwide. The objective of this article is to present our recommendations for the use of TAVI, based on a multidisciplinary evaluation of recently published evidence. We systematically searched and summarized published data (2008-2011) on benefits, risks, and cost-effectiveness of TAVI. We also examined ethical issues and organizational aspects of delivering the intervention. We discussed the soundness and applicability of our recommendations with clinical experts active in the field. The published TAVI results for high-risk and/or inoperable patients are promising in terms of survival, function, quality of life, and cost-effectiveness, although we noted large variability in the survival rates at 1 year and in the frequency of important adverse outcomes such as stroke. Until more data from randomized controlled trials and registries become available, prudence and discernment are necessary in the choice of patients most likely to benefit. Patients need to be well-informed about gaps in the evidence base. Our recommendations support the use of TAVI in the context of strict conditions with respect to patient eligibility, the patient selection process, organizational requirements, and the tracking of patient outcomes with a mandatory registry.

Patients with aortic stenosis referred for TAVI: treatment decision, in-hospital outcome and determinants of survival

Aims

To assess treatment decision and outcome in patients referred for transcatheter aortic valve implantation (TAVI) in addition to predictive factors of mortality after TAVI.

Methods

Three-centre prospective observational study including 358 patients. Endpoints were defined according to the Valve Academic Research Consortium.

Results

Of the 358 patients referred for TAVI, TAVI was performed in 235 patients (65%), surgical aortic valve replacement (AVR) in 24 (7%) and medical therapy (MT) in 99 (28%). Reasons to decline TAVI in favour of AVR/MT were patient preference (29%), peripheral vascular disease (15%) and non-severe aortic stenosis (11%). The logistic EuroSCORE was significantly higher in patients who underwent TAVI and MT in comparison with those undergoing AVR (19 vs. 10%, p = 0.007). At 30 days, all-cause mortality and the combined safety endpoint were 9 and 24% after TAVI and 8 and 25% after AVR, respectively. All-cause mortality was significantly lower in the TAVI group compared with the MT group at 6 months, 1 year and 2 years (12% vs. 22%, 21% vs. 33% and 31% vs. 55%, respectively, p < 0.001). Multivariable analysis revealed that blood transfusion (HR: 1.19; 95% CI: 1.05–1.33), pre-existing renal failure (HR: 1.18; 95% CI: 1.06–1.33) and STS score (HR: 1.06; 95% CI: 1.02–1.10) were independent predictors of mortality at a median of 10 (IQR: 3–23) months after TAVI.

Conclusions

Approximately two-thirds of the patients referred for TAVI receive this treatment with gratifying short- and long-term survival. Another 7% underwent AVR. Prognosis is poor in patients who do not receive valve replacement therapy.

Decellularized homologous tissue-engineered heart valves as off-the-shelf alternatives to xeno- and homografts

Decellularized xenogenic or allogenic heart valves have been used as starter matrix for tissue-engineering of valve replacements with (pre-)clinical promising results. However, xenografts are associated with the risk of immunogenic reactions or disease transmission and availability of homografts is limited. Alternatively, biodegradable synthetic materials have been used to successfully create tissue-engineered heart valves (TEHV). However, such TEHV are associated with substantial technological and logistical complexity and have not yet entered clinical use. Here, decellularized TEHV, based on biodegradable synthetic materials and homologous cells, are introduced as an alternative starter matrix for guided tissue regeneration. Decellularization of TEHV did not alter the collagen structure or tissue strength and favored valve performance when compared to their cell-populated counterparts. Storage of the decellularized TEHV up to 18 months did not alter valve tissue properties. Reseeding the decellularized valves with mesenchymal stem cells was demonstrated feasible with minimal damage to the reseeded valve when trans-apical valve delivery was simulated. In conclusion, decellularization of in-vitro grown TEHV provides largely available off-the-shelf homologous scaffolds suitable for reseeding with autologous cells and trans-apical valve delivery.

Anesthetic considerations during minimally invasive mitral valve surgery

Advances in instruments and visualization tools as well as circulatory systems for cardiopulmonary bypass during the late 1990s have stimulated widespread adoption of minimally invasive mitral valve surgery (MIMVS). Today, MIMVS is the standard approach for many surgeons and institutions. There are multiple benefits of MIMVS. Patient satisfaction and improved cosmesis are important. Additionally, studies have consistently shown faster recovery times and less associated pain with MIMVS. Statistically significant improvement in bleeding, transfusion, incidence of atrial fibrillation, and time to resumption of normal activities with MIMVS has also been shown when comparing MIMVS with conventional mitral surgery. Most important, these benefits have been achieved without sacrificing perioperative safety or durability of surgical repair. Although a steep learning curve still exists given the high level of case complexity, continued development fueled by increasing patient demand may allow for even further expansion in the use of minimal invasive techniques.

Transcatheter aortic valve replacement: the changing paradigm of aortic stenosis treatment

Aortic stenosis is the most common cause for valvular surgery in the USA. For nearly 50 years, surgical aortic valve replacement has been the standard of care for symptomatic patients; unfortunately, a significant number of patients are not referred to surgery owing to advanced comorbidities and age. Transcatheter aortic valve replacement has emerged as an effective therapy for patients at high risk for surgery. Through device innovations and accumulated experience, the safety and efficacy of the procedure has improved since its inception. Transcatheter valve replacement has been found superior to medical therapy in inoperable patients with aortic stenosis, yet many questions remain as to which patients are appropriate for this exciting and novel therapy.

Local versus general anesthesia for transfemoral aortic valve implantation

BACKGROUND

Transcatheter aortic valve implantation (TAVI) represents a novel option for elderly with severe aortic valve stenosis who are denied surgical aortic valve replacement due to high perioperative risk. While transfemoral TAVI generally is being performed in general anesthesia (GA), TAVI under local anesthesia plus mild sedation (LAPS) might be an effective and safe alternative.

METHODS

In a single-centre analysis, we assessed clinical data, preoperative risk scores (STS-Score), echocardiography, periprocedural data and labor costs in 74 patients undergoing transfemoral TAVI under GA (n = 33) and LAPS (n = 41).

RESULTS

Patients who underwent TAVI in LAPS presented significantly more often with pulmonary hypertension and impaired renal function, and tended to have a higher STS score and more severe symptoms (higher NYHA class) versus the GA group. There were no significant differences in procedure-related 30-day mortality or complications between groups. The peak systolic and mean central aortic pressure were significantly higher in the LAPS group, while at the same time these patients required significantly less often periprocedural adrenergic support. Intervention time was shorter in the LAPS group due to avoidance of surgical cut-down of the access site. Moreover, total procedure time was significantly shorter and labor costs were lower in the LAPS group. Patients who underwent TAVI in LAPS could be mobilized significantly earlier.

CONCLUSION

Our study indicates that TAVI under LAPS is as effective and safe as TAVI under GA. Furthermore, total procedure time, intervention time and labor costs could be reduced by LAPS. Mobilization of patients could be achieved earlier. We therefore consider LAPS to be favorable in patients undergoing transfemoral TAVI.

[Percutaneous catheter-based implantation of artificial pulmonary valves in patients with congenital heart defects]

BACKGROUND

Percutaneous catheter-based implantation of artificial heart valves is a new technique that may supplement surgery and which may be used more in the future. We here report our first experience with implantation of artificial pulmonary valves in children with congenital heart defects.

MATERIAL AND METHODS

Eligible patients were those with symptoms of heart failure combined with stenosis and/or insufficiency in an established artificial right ventricular outflow tract. The valve was inserted through a catheter from a vein in the groin or neck. Symptoms, echocardiography, invasive measurements and angiography were assessed for evaluation of treatment effect. Our treatment results are reported for the period April 2007-September 2009.

RESULTS

Ten patients (seven men and three women, median age 17 years) were assessed. The procedure reduced pressure in the right ventricle (p = 0.008) and resolved the pulmonary insufficiency in all patients. The median time in hospital was two days. No patients had complications that were directly associated with the implantation procedure. One patient developed a pseudoaneurysm in the femoral artery, another had a short-lasting fever two days after the procedure and one patient experienced a stent fracture that required surgery 9 months after the implantation. After 6 months all patients had a reduced pressure gradient in the right ventricular outflow tract (p = 0.008), the pulmonary insufficiency had improved (p = 0.006) and they all reported improval of symptoms. These results persisted for at least 24 months for the four patients who were monitored until then.

INTERPRETATION

Percutaneous catheter-based implantation of artificial pulmonary valves improves hemodynamics in the right ventricle of selected patients with congenital heart defects. A randomized controlled study should be undertaken to provide a stronger evidence-base for usefulness of this procedure.

[Transapical aortic valve implantation--indications, risks and limitations]

Calcified aortic stenosis is the predominant valve disease in the western world. Currently, surgical aortic valve replacement is the gold standard procedure for symptomatic severe aortic stenosis that can be performed with low morbidity and mortality. The prevalence of aortic stenosis increases with age, and the incidence of several comorbidities also unavoidably elevates the risk of surgical treatment. Therefore, the most adequate and gentle treatment is needed especially for this population. Since the first transcatheter aortic valve implantation (TAVI) was performed in 2002, the main implanting routes are the transfemoral, retrograde access through the common femoral artery, and the antegrade, transapical approach via anterolateral minithoracotomy. Meanwhile, TAVI has become an alternative treatment for patients who are not suitable candidates for surgical therapy in some centers.The initial clinical results are promising and have confirmed the feasibility of this technique. Due to the restricted long-term data, conventional aortic valve replacement still remains the standard for the treatment of aortic stenosis. Selection of the suitable therapy approach (surgical replacement, transfemoral or transapical aortic valve implantation) must consider each patient's specific risk profile and individual indication. Prospective, randomized trials will be necessary to assess the individual survival benefit of TAVI for various risk populations and to extend the indication.

Transcatheter aortic valve implantation in a heart transplant recipient: a case report

Transcatheter aortic valve implantation (TAVI) has evolved into a feasible therapeutic option for the management of selected patients with severe aortic stenosis and high or prohibitive risk for standard surgery. Symptomatic severe aortic stenosis occasionally occurs in the allograft long after heart transplantation. Because of specific characteristics and comorbidities of heart transplant recipients, these patients may be considered candidates for this less invasive approach. We report a first case of successful transapical TAVI in a heart transplant recipient with symptomatic severe calcific aortic valvular disease and relevant comorbidities long after heart transplantation.

Incidence and treatment of procedural cardiovascular complications associated with trans-arterial and trans-apical interventional aortic valve implantation in 412 consecutive patients

OBJECTIVE

Trans-catheter aortic valve implantation (TAVI) technology is rapidly evolving, with 412 procedures having been performed at our institution. Herein, we report a complete, prospective analysis of complications occurring during transvascular and trans-apical implantations with two different prostheses.

METHODS

Between June 2007 and June 2010, 412 patients (258 female, mean age 80.3±7.2 years, logistic EuroSCORE (European System for Cardiac Operative Risk Evaluation) 20.2%±13.0%) underwent TAVI through either a retrograde (n=252 transfemoral, n=28 transaxillary, and n=5 transaortic) or antegrade (n=127 trans-apical) approach at our institution. The trans-apical access was chosen only in cases where transvascular implantation was not possible. As many as 283 CoreValve and 129 Edwards Sapien prostheses were implanted.

RESULTS

Thirty-day survival was 90.9%. Vascular complications occurred in 42 patients (10.2%). In four patients, lethal aortic root (n=3) or abdominal (n=1) aortic rupture occurred. Pericardial effusion developed in 53 patients (12.8%), which resulted in cardiac tamponade in 12 patients (2.9%). Twenty-three patients (5.6%) with valve malplacement were treated interventionally. In five patients (1.2%), emergency institution of cardiopulmonary bypass was required during the procedure for temporary support; all patients survived. Seventeen patients underwent re-intervention on the catheter valve (4.1%).

CONCLUSIONS

With growing experience, complications with TAVI may be avoided by proper patient selection and skillful management. Other complications, when they occur, require a specific treatment algorithm to avoid delay in decision making. A considerable number of complications after TAVI require surgical treatment. Therefore, the ideal environment for TAVI procedures is a hybrid operating room, where a multidisciplinary team of surgeons, cardiologists, and anesthesiologists is best fitted to meet the current needs associated with TAVI technology. A reduction in complications was seen after 300 cases. This finding attests to the complexity of the procedure in addition to the experience required to reduce the incidence of complications.

A novel method of ventricular closure following transapical access

AIM

left ventricular direct access and sheath placement through a minithoracotomy has been utilized to allow minimally invasive valvular surgery. One potential problem encountered is the closure of the ventricular puncture incision in a beating heart. Our aim was to develop a sutureless closure technique that does not leave behind a foreign body exposed on the endocardial surface.

MATERIALS & METHODS

we sought to evaluate this concept in vivo in the porcine model. Thoracotomy was performed with exposure of the beating heart. A total of six Fr sheaths were placed in the transapical territory in the left and right ventricle with fluoroscopy confirming sheath placement. The incisions were then closed using three types of commercially available femoral vascular closure systems (AngioLink, StarClose and Mynx).

RESULTS

one animal had one device placed in the left and right ventricle and closure was then immediately observed intraoperatively (AngioLink). Another animal had five devices (StarClose) placed in the left ventricle and one in the right ventricle, with closure observed within 1 min of application. A third animal had the sheath removed and spontaneous closure then observed at two sites. These two sites continued to bleed for 2-3 min. The same animal had an application of six Mynx devices at sheath sites using an extravascular bio-inert sealant. One site failed and the five others were immediately successful. Histopathology evaluation confirmed no evidence of device exposure on the endovascular surface in the first two animals. The Mynx device sealant was present on the endocardial surface at closure sites postmortem.

CONCLUSION

we have introduced a new concept of using vascular closure systems for closing ventricular wall stab incisions after transapical surgery. We intend to expand the scale of animal studies and evaluate the device for any modifications in the mechanism or technique for ultimate use in human subjects.

Standardized endpoint definitions for transcatheter aortic valve implantation clinical trials: a consensus report from the Valve Academic Research Consortium

OBJECTIVES

To propose standardized consensus definitions for important clinical endpoints in transcatheter aortic valve implantation (TAVI), investigations in an effort to improve the quality of clinical research and to enable meaningful comparisons between clinical trials. To make these consensus definitions accessible to all stakeholders in TAVI clinical research through a peer reviewed publication, on behalf of the public health.

BACKGROUND

Transcatheter aortic valve implantation may provide a worthwhile less invasive treatment in many patients with severe aortic stenosis and since its introduction to the medical community in 2002, there has been an explosive growth in procedures. The integration of TAVI into daily clinical practice should be guided by academic activities, which requires a harmonized and structured process for data collection, interpretation, and reporting during well-conducted clinical trials.

METHODS AND RESULTS

The Valve Academic Research Consortium established an independent collaboration between Academic Research organizations and specialty societies (cardiology and cardiac surgery) in the USA and Europe. Two meetings, in San Francisco, California (September 2009) and in Amsterdam, the Netherlands (December 2009), including key physician experts, and representatives from the US Food and Drug Administration (FDA) and device manufacturers, were focused on creating consistent endpoint definitions and consensus recommendations for implementation in TAVI clinical research programs. Important considerations in developing endpoint definitions included (i) respect for the historical legacy of surgical valve guidelines; (ii) identification of pathophysiological mechanisms associated with clinical events; (iii) emphasis on clinical relevance. Consensus criteria were developed for the following endpoints: mortality, myocardial infarction, stroke, bleeding, acute kidney injury, vascular complications, and prosthetic valve performance. Composite endpoints for TAVI safety and effectiveness were also recommended.

CONCLUSION

Although consensus criteria will invariably include certain arbitrary features, an organized multidisciplinary process to develop specific definitions for TAVI clinical research should provide consistency across studies that can facilitate the evaluation of this new important catheter-based therapy. The broadly based consensus endpoint definitions described in this document may be useful for regulatory and clinical trial purposes.

An assessment of the cost of percutaneous pulmonary valve implantation (PPVI) versus surgical pulmonary valve replacement (PVR) in patients with right ventricular outflow tract dysfunction

BACKGROUND

Percutaneous pulmonary valve implantation (PPVI) using the Melody * transcatheter pulmonary valve is a new procedure introduced in 2000 as a less invasive treatment for right ventricular outflow tract (RVOT) dysfunction. The aim of this new procedure is to restore pulmonary valve competence without the need of open-chest operation. By prolonging the conduit lifespan, it delays surgical pulmonary valve replacement (PVR) and it can therefore potentially reduce the number of open-chest interventions over a patient's lifetime. PPVI has been shown to be feasible and safe and can be performed with a low complication rate.

OBJECTIVES AND METHODS

The aim of this study is to assess the cost of PPVI and the cost of surgical pulmonary valve replacement (PVR) in patients with right ventricular outflow tract dysfunction using a cohort simulation model applied to the UK population.

RESULTS

The model resulted in an estimate of mean cost per patient of £5,791 when PPVI is unavailable as a treatment option and in an estimate of mean cost per patient of £8,734 when PPVI is available over the 25-year period of analysis. After sensitivity analysis was undertaken the results showed that the mean per patient cost difference in implementing PPVI over 25 years as compared to surgical PVR lies somewhere between £2,041 and £3,913.

LIMITATIONS

Given the lack of long-term data on treatment progression, the cost estimates derived here are subject to considerable uncertainty, and extensive sensitivity analysis has been used to counter this. Consequently this study is merely indicative of the levels of cost which can be expected in a cohort of 1,000 patients faced with a choice of treatment with PPVI or surgery. It is not a cost-effectiveness study but it helps place current knowledge on short-term benefits into context.

CONCLUSIONS

As this analysis shows PPVI is associated with a relatively small increase in treatment management costs over a long time period. It is left entirely to the reader to value whether this inferred increase in long-term cost is worthwhile given the known short-term benefits and any personal judgement formed over long-term benefit.

Apico-Aortic Conduit for severe aortic stenosis: Technique, applications, and systematic review

Patients referred for aortic valve replacement are often elderly and may have increased surgical risk associated with ascending aortic calcification, left ventricular dysfunction, presence of coronary artery disease, previous surgery, and/or presence of several co-morbidities. Some of these patients may not be considered candidates for conventional surgery because of their high risk profile. While transcatheter aortic valve replacement constitutes a widely accepted alternative, some patients may not be eligible for this modality due to anatomic factors. Apico-Aortic Conduit (AAC) insertion (aortic valve bypass surgery) constitutes a possible option in those patients. Apico-Aortic Conduit is not a new technique, as it has been used for decades in both pediatric and adult populations. However, there is a resurging interest in this technique due to the expanding scope of elderly patients being considered for the treatment of aortic stenosis. Herein, we describe our surgical technique and provide a systematic review of recent publications on AAC insertion, reporting that there is continued use and several modifications of this technique, such as performing it through a small thoracotomy without the use of the cardiopulmonary bypass.