Retrograde percutaneous aortic valve implantation for critical aortic stenosis

Native Aortic Valve Resection Using a Novel Blade-Based Device

OBJECTIVE

The aim of this study was to validate the use of a new resection device in patient candidates for surgical aortic valve replacement. We evaluated the efficacy of this new circular blade to resect the aortic valve and the efficacy to collect the debris during the resection.

METHODS

For this study, a single size instrument was used, with an external diameter of 22 mm, and patients were selected on the basis of the preoperative assessment of the aortic diameters.

RESULTS

From October 2018 to June 2019, 10 patient candidates for surgical aortic valve replacement were selected to undergo native aortic valve resection using a new device, before surgical valve implantation. The mean age of the patients was 74 ± 7.6 years, and 8 of 10 were male. The mean aortic annulus diameter, measured before the procedure, was 25.7 ± 1.57 mm. The resection was complete in 9 (90%) patients. In 1 patient, due to an imprecise positioning of the device, the valve resection was partial. None of the patients showed signs or symptoms due to debris embolism. In all patients, the postoperative course was uneventful.

CONCLUSIONS

These preliminary results show that resection of the aortic valve using a circular foldable blade is feasible. This prototype, used during conventional surgery even through a small incision, provided an efficient tool to easily resect the valve without debris release.

Alternative Access for Transcatheter Aortic Valve Replacement: A Comprehensive Review

Transfemoral is the most widely used access to perform transcatheter aortic valve replacement (TAVR). However, alternative access is needed in up to 21% of patients with TAVR because of a myriad of factors. The authors provide a comprehensive review on alternative access for TAVR, discussing the relevant data and providing the pros and cons of each access route.

Intentional Percutaneous Laceration of the Anterior Mitral Leaflet to Prevent Outflow Obstruction During Transcatheter Mitral Valve Replacement: First-in-Human Experience

OBJECTIVES

This study sought to use a new catheter technique to split the anterior mitral valve leaflet (AML) and prevent iatrogenic left ventricular outflow tract (LVOT) obstruction immediately before transcatheter mitral valve replacement (TMVR).

BACKGROUND

LVOT obstruction is a life-threatening complication of TMVR, caused by septal displacement of the AML.

METHODS

The procedure was used in patients with severe mitral valve disease and prohibitive surgical risk. Patients either had prior surgical mitral valve ring (n = 3) or band annuloplasty (n = 1) or mitral annular calcification with stenosis (n = 1). Iatrogenic LVOT obstruction or transcatheter heart valve dysfunction was predicted in all based on echocardiography and computed tomography. Transfemoral coronary guiding catheters directed an electrified guidewire across the center and base of the AML toward a snare in the left atrium. The externalized guidewire loop was then electrified to lacerate the AML along the centerline from base to tip, sparing chordae, immediately before transseptal TMVR.

RESULTS

Five patients with prohibitive risk of LVOT obstruction or transcatheter heart valve dysfunction from TMVR successfully underwent LAMPOON, with longitudinal splitting of the A2 scallop of the AML, before valve implantation. Multiplane computed tomography modeling predicted hemodynamic collapse from TMVR assuming an intact AML. However, critical LVOT gradients were not seen following LAMPOON and TMVR. Doppler blood flow was seen across transcatheter heart valve struts that encroached the LVOT, because the AML was split. Transcatheter heart valve function was unimpeded.

CONCLUSIONS

This novel catheter technique, which resembles surgical chord-sparing AML resection, may enable TMVR in patients with prohibitive risk of LVOT obstruction or transcatheter heart valve dysfunction.

Transcatheter aortic valve implantation

With the improvement in the overall life expectancy, the incidence of aortic stenosis has been increasing. Although aortic valve replacement is a standard therapy, many patients do not undergo surgery for various reasons, including advanced age or the presence of multiple comorbidities. Transcatheter aortic valve implantation (TAVI) has been proposed as a less invasive and equally effective treatment for inoperable or high-risk symptomatic aortic stenosis. Numerous rigorous global clinical trials, as well as a pivotal clinical trial in Japan, have been conducted. In this review, we provide data on the development of TAVI worldwide and discuss the prospects for TAVI in Japan.

Antegrade approach for TAVR with total occlusion of the descending aorta

The antegrade approach for aortic valve interventions is well known but has not been widely used for transcatheter aortic valve replacement (TAVR) procedures. We encountered a patient with no possibility of retrograde access due to a totally occluded abdominal aorta who had a failed attempt at apical TAVR. We describe antegrade TAVR despite occlusion of the abdominal aorta, with the arterial limb of the requisite veno-arterial loop created using bilateral arm access, a novel version of the previously described antegrade approach.

Percutaneous heart valves; past, present and future

Percutaneous heart valves provide a promising future for patients refused surgery on the grounds of significant technical challenges or high risk for complications. Since the first human intervention more than 10 years ago, over 50 different types of valves have been developed. The CoreValve and Edwards SAPIEN valves have both experienced clinical trials and the latter has gained FDA approval for implantation in patients considered inoperable. Current complications, such as major vascular bleeding and stroke, prevent these valves from being commonly deployed in patients considered operable in conventional surgery. This review focuses on the past and present achievements of these valves and highlights the design considerations required to progress development further. It is envisaged that, with continued improvement in valve design and with increased clinical and engineering experience, percutaneous heart valve replacement may one day be a viable option for lower-risk operable patients.

A new type of aortic valved stent with good stability and no influence on coronary artery

Background

To evaluated the feasibility and safety of new aortic valved stents in transcatheter aortic valve implantation (TAVI) using retrograde approach by in vitro testing and animal implantation.

Materials and Methods

The fluid passing test, expanding and releasing tests, static and releasing tests in tube were performed for new valved stents. Transvalvular pressure gradient, effective orifice area, pre-implantation and post-implantation regurgitant volume for the new stents were detected. Then, the new stents were implanted in six pigs using retrograde approach. These pigs were euthanized 12 h after the implantation for anatomic evaluation.

Results

In vitro tests showed that the closure of the new stents leaflets were effective, and stents could be released through catheter, then expanded completely and fixed fast in the tube. The coronary artery flow rates did not changed significantly after implantation (P > 0.05), while aortic regurgitant volumes were obviously reduced (P < 0.05). No significant difference in the transvalvular pressure gradient and effective orifice area of the new stents implanted within or above the valve leaflets was found (P > 0.05). In vivo experiments indicated that TAVI was successfully performed in six pigs using retrograde approach. However, one pig was died 10 h after the implantation since the stent was not expanded completely. The leaflets in stents were opening well and no valvular regurgitation was observed in the other five pigs. And thrombosis was not found.

Discussion and Conclusion

The new type of aortic valved stent designed in this study was characterized with good stability and could avoid the impact caused by valve leaflets on the coronary artery.

Which way in? The necessity of multiple approaches to transcatheter valve therapy

TAVI (transcatheter aortic valve implantation) is a less invasive treatment of the stenotic aortic valve while avoiding midline sternotomy and cardiopulmonary bypass. A crimped biological valve on a self-expanding or balloonexpandable stent is inserted antegradely or retrogradely under fluoroscopy, and deployed on the beating heart. Among the worldwide TAVI programs, many different concepts have been established for the choice of the access site. Whether retrograde or antegrade TAVI should be considered the superior approach is matter of an ongoing debate. The published literature demonstrates safety of all techniques if performed within a dedicated multidisciplinary team. Since there is no data providing evidence if one approach is superior to another, we conclude that an individualized patient-centered decision making process is most beneficial, taking advantage of the complementarity of the different access options. The aim of this article is to give an overview of the current practice of access techniques for transcatheter based valve treatment and to outline the respective special characteristics.

Transient severe aortic regurgitation and left ventricular dysfunction due to a stuck leaflet in a patient undergoing percutaneous transcatheter aortic valve implantation

We report the case of a 78-year-old patient who underwent transcatheter aortic valve implantation. During the deployment, the leaflets of the implanted valve appeared to be stuck in calcium protruding from the native aortic leaflets, resulting in transient severe aortic regurgitation leading to cardiac arrest with successful cardiac resuscitation. Transient severe aortic regurgitation secondary to the mechanical failure of the deployed valve can lead to serious clinical consequences.

Minimally invasive cardiac surgery: transapical aortic valve replacement

Minimally invasive cardiac surgery is less traumatic and therefore leads to quicker recovery. With the assistance of engineering technologies on devices, imaging, and robotics, in conjunction with surgical technique, minimally invasive cardiac surgery will improve clinical outcomes and expand the cohort of patients that can be treated. We used transapical aortic valve implantation as an example to demonstrate that minimally invasive cardiac surgery can be implemented with the integration of surgical techniques and engineering technologies. Feasibility studies and long-term evaluation results prove that transapical aortic valve implantation under MRI guidance is feasible and practical. We are investigating an MRI compatible robotic surgical system to further assist the surgeon to precisely deliver aortic valve prostheses via a transapical approach. Ex vivo experimentation results indicate that a robotic system can also be employed in in vivo models.

Transcatheter aortic valve replacement: transapical resection of the aortic valve in vivo

The resection of pulmonary valves has already been demonstrated in an experimental beating-heart model. The aim of this study was to analyse the transapical laser-assisted resection of aortic valves in an in vivo porcine model in a non-beating heart. The resection was performed in a porcine model (n = 10) using a Thullium:YAG laser. After establishing a standard extracorporeal circulatory support, the aortic valve isolation chamber (AVIC) system was inserted transapically. The resection of the aortic leaflets was carried out step-by-step in the arrested heart. The AVIC implantation, the resection process, and the gross anatomy of intracardiac lesions were analysed. The procedure for installing the AVIC took 5.8 ± 1.5 min. A sealed chamber was achieved in 9/10 cases. The resection of the valves was performed in 8/10 and completed in 7/10 cases. The resection took, on average, 7.4 ± 2.7 min/cusp. In 9/10 cases, the sealing was sufficient. Gross anatomy and histological analysis demonstrated only superficial damage to the surrounding tissue. In this study, the in vivo on-pump isolation of the left ventricular outflow tract and the laser resection of the native aortic valve could be demonstrated successfully. Nevertheless, this model is the next step towards a beating-heart resection of the aortic valve using the isolation chamber.

Percutaneous aortic valve replacement. Part 3: Balloon counterpulsation of a novel temporary aortic valve

A previously published two-part study described an engineering design of a percutaneous aortic valve (PAV) replacement system, which utilizes a novel temporary aortic valve (TAV) support to improve procedural outcomes and safety. Conceptually, this investigational approach can promote accurate PAV placement, procedural hemodynamic stability, smaller catheter delivery system, reduction in PAV regurgitation, reduction in conduction and vascular complications. The balloon TAV can potentially facilitate the PAV replacement procedure by serving as the patient's surrogate aortic valve while the native valve is pretreated and replaced. The original TAV is designed to function with an effective aortic stenosis and insufficiency in moderate ranges, which lessens from the patient's more critical valve condition, should be well tolerated when the native valve becomes nonfunctional during the replacement process. Further optimization of the TAV's hemodynamic profile could further improve the system's overall performance and enhance the realization of a truly minimally invasive, cath lab-based PAV replacement procedure comparable to that of percutaneous coronary intervention. This study explores design permutations from the original published TAV, including varying the number of balloons and adding balloon counterpulsations, to improve upon its hemodynamic profile to better serve as the patient's surrogate valve and the overall PAV replacement procedure.

Qualitative haemodynamic validation of a percutaneous temporary aortic valve: a proof of concept study

The concept of temporary aortic valves has been suggested in the clinical settings of acute aortic regurgitation and transcatheter aortic valve replacement procedure (TAVR). In TAVR, suggestions have been made to pre-treat or remove the diseased aortic valve prior to implantation of the replacement valve. A successful temporary aortic valve must demonstrate the ability to prevent life-threatening haemodynamics of massive aortic regurgitation. A novel temporary aortic valve (TAV) design, comprised of inflatable balloon elements as a check-valve, can readily be deployed and retrieved via a catheter-system. A simple flow model is set up to test the TAV's performance in severe aortic regurgitation. With induced aortic regurgitation, placement of the TAV is found to increase the distal aortic diastolic pressure, to reduce the widened pulse pressure, to protect proximal aorta-left ventricle from diastolic pressure elevation and to reduce the aortic regurgitant volume. In conclusion, continued development of the TAV system can lead to a successful temporary aortic valve to be used in various appropriate clinical settings.

Transapical aortic valve replacement under real-time magnetic resonance imaging guidance: experimental results with balloon-expandable and self-expanding stents

OBJECTIVE

Aortic valves have been implanted on self-expanding (SE) and balloon-expandable (BE) stents minimally invasively. We have demonstrated the advantages of transapical aortic valve implantation (tAVI) under real-time magnetic resonance imaging (rtMRI) guidance. Whether there are different advantages to SE or BE stents is unknown. We report rtMRI-guided tAVI in a porcine model using both SE and BE stents, and compare the differences between the stents.

METHODS

A total of 22 Yucatan pigs (45-57 kg) underwent tAVI. Commercially available stentless bioprostheses (21-25 mm) were mounted on either BE platinum-iridium stents or SE-nitinol stents. rtMRI guidance was employed as the intraoperative imaging. Markers on both types of stents were used to enhance visualization in rtMRI. Pigs were allowed to survive and had follow-up MRI scans and echocardiography at 1, 3, and 6 months postoperatively.

RESULTS

rtMRI provided excellent visualization of the aortic valve implantation mounted on both stent types. The implantation times were shorter with the SE stents (60 ± 14s) than with the BE stents (74 ± 18s), (p=0.027). The total procedure time was 31 and 37 min, respectively (p=0.12). It was considerably easier to manipulate the SE stent during deployment, without hemodynamic compromise. This was not always the case with the BE stent, and its placement occasionally resulted in coronary obstruction and death. Long-term results demonstrated stability of the implants with preservation of myocardial perfusion and function over time for both stents.

CONCLUSIONS

SE stents were easier to position and deploy, thus leading to fewer complications during tAVI. Future optimization of SE stent design should improve clinical results.

Percutaneous aortic valve replacement (part 2): Miniaturization of the delivery system based on the novel temporary valve technology

Percutaneous aortic valve replacement remains an investigational procedure challenged by multiple key issues. In part 1 of this 2 part series, the issue of precise placement of the percutaneous aortic valve was addressed by a novel design of a delivery and deployment system. The design and use of a hemodynamics supporting temporary aortic valve was highlighted, which can stabilize the hemodynamic and local flow conditions for a more controlled and precise placement of the percutaneous aortic valve. In this part 2 study, the issue of vascular access complications is addressed. The current large French size catheter systems can cause significant vascular injuries; the catheter diameter must be reduced for this procedure to be safe and routine. The hemodynamic support of the temporary aortic valve system allows for the formulation of a novel approach to reduce the catheter-delivery system. The miniaturization strategies consist of pretreatment of the aortic annulus and assembly of the percutaneous aortic valve apparatus in a piecemeal fashion of smaller components. Each component would, therefore, require a smaller diameter delivery catheter. The combined strategies as described in this 2 part series aim at realizing the percutaneous aortic valve replacement as a routine, fully percutaneous and cath lab-based.

Transcatheter aortic valve implantation: review of the nature, management, and avoidance of procedural complications

Transcatheter aortic valve implantation (TAVI) is becoming a reality in the management of patients with severe aortic stenosis and high or prohibitive risk for standard surgical management. Current understanding of the potential adverse events associated with this procedure is limited. Risks associated with TAVI differ from those related to surgical valve replacement and include vascular injury; stroke; cardiac injury such as heart block, coronary obstruction, and cardiac perforation; paravalvular leak; and valve misplacement. The clinical experience of multiple centers experience with different valve implantation systems and techniques was reviewed. Awareness of how complications occur might help in their avoidance, recognition, and management. Ultimately, improved understanding of the potential complications associated with TAVI might help improve outcomes and allow wider application of this therapy.

[Transcatheter-based aortic valve implantation. Present and future technologies]

The calcified aortic stenosis is the dominating valve disease. Patients affected are most common elderly people in the 8th or 9th decade of their life who often show associated comorbidities like reduced left ventricular function, impaired renal function, pulmonary hypertension, and further diseases (diabetes mellitus, stroke, chronic obstructive pulmonary disease). In many cases perioperative morbidity and mortality are too high for surgical valve replacement and patients are rejected. Nevertheless, prognosis of aortic stenosis is worse, if the typical symptoms like dyspnea on exertion, syncope, and angina occur. The transcatheter aortic valve implantation is an alternative treatment for this particular group of patients. The aortic valve bioprosthesis consists of a balloon-expandable stent or a self-expandable frame, in which a valve of bovine or porcine pericardium is incorporated. The implantation is performed by retrograde access via the femoral artery; the balloon-expandable prosthesis can also be implanted by transapical approach. Alternatively, the subclavian artery is chosen for access. More frequently, the implantation is performed in analgosedation with the patient awake that favors the transfemoral approach. A further reduction of the available prosthesis and new types of valves which are under current experimental tests and clinical evaluation contribute to this development.

Vascular access site complications after percutaneous transfemoral aortic valve implantation

BACKGROUND AND PURPOSE

Transcatheter aortic valve implantation (TAVI) is a rapidly emerging treatment option for patients with aortic valve stenosis and high surgical risk. Different access routes have been proposed for TAVI including transapical, transsubclavian and transfemoral, with percutaneous transfemoral being the preferred because least invasive and nonsurgical. However, vascular access site complications due to the large-bore delivery catheters remain an important clinical issue, particularly with respect to the elderly patient collective typically considered for TAVI. In the study, the authors analyzed their 4-year TAVI experience with respect to vascular complications and their management in patients undergoing completely percutaneous transfemoral TAVI procedures.

PATIENTS AND METHODS

Since 2006, TAVI was performed in 101 consecutive patients at the West German Heart Center Essen. 33 patients underwent transapical TAVI, eight patients transfemoral TAVI with surgical access or closure, and 60 patients percutaneous transfemoral TAVI using two commercially available prosthetic valve devices.

RESULTS

Completely percutaneous TAVI was technically successful in all but one patient with malpositioning in the aortic arch during valve retrieval. There was no intraprocedural death and 30-day mortality was 12% (7/60). Vascular access site complications occurred in 19 patients (32%), necessitating surgical repair in six of them (10%). Complications included retroperitoneal hematoma (n = 2), iliac or femoral artery dissection (n = 10), (pseudo)aneurysm formation (n = 3), and closure device-induced vessel stenosis/ occlusion (n = 6). Of these, 13 cases could be managed either conservatively (n = 5) or by contralateral endovascular treatment (n = 8).

CONCLUSION

Completely percutaneous TAVI has a high acute success rate with low intraprocedural and 30-day mortality. The patient collective appears to be prone to vascular complications which remain an important limitation of this novel technique. Although conservative or endovascular management is possible in the majority of cases, further technological developments are obliged to reduce the vascular complication rate.

A new cone-shaped aortic valve prosthesis for orthotopic position: an experimental study in Swine

The aim of this experimental study was to evaluate a newly designed cone-shaped aortic valve prosthesis (CAVP) for one-step transcatheter placement in an orthotopic position. The study was conducted in 15 swine using either the transcarotid (11 animals) or the transfemoral (4 animals) artery approach. A 12- or 13-Fr sheath was inserted via arterial cutdown. The CAVP was deployed under fluoroscopic control and its struts, by design, induced significant native valve insufficiency. CAVP function was evaluated by aortography and aortic pressure curve tracing. In 11 of 15 swine the CAVP was properly deployed and functioned well throughout the scheduled period of 2-3 h. In three swine the CAVPs were placed lower than intended, however, they were functional even in the left ventricular outflow tract position. One swine expired due to inadvertent low CAVP placement that caused both aortic regurgitation and immobilization of the anterior mitral valve leaflet by the valve struts. We conclude that this design of CAVP is relatively easy to deploy, works well throughout a short time period (2-3 h), and, moreover, seems to be reliable even in a lower-than-orthotopic position (e.g., infra-annulary space). Longer-term studies are needed for its further evaluation.

Percutaneous transcatheter aortic valve implantation: Evolution of the technology

Aortic stenosis (AS) is currently the most common valvular abnormality in developed countries. The gold standard treatment of severe symptomatic AS is surgical aortic valve replacement. Mechanical valves were initially the prostheses of choice; with improvement of surgical technique and results, and increased durability of bioprosthetic valves, there has been a trend toward increasing use of bioprostheses. Concurrently, percutaneous technology has advanced exponentially, and the first human percutaneous aortic valve replacement (PAVR) became a reality in 2002. Various groups have now reported their early experiences with PAVR using different technologies. This new treatment modality is evolving very rapidly. There are currently 2 devices being used in clinical trials; several more devices have first-in-man results and others in preclinical development. It appears that PAVR will most likely become a viable option for selected patients in the near future. For these technologies to continue to improve and benefit patients, cross-specialty teamwork is vital. Treatment of severe AS will greatly evolve as these new and emerging technologies improve. Enhancement in device designs and increasing operator experience will make this technology safer and allow its application to a wider patient population.

A modified "preclosure" technique after percutaneous aortic valve replacement

OBJECTIVES

To evaluate the feasibility, safety and efficacy of suture-mediated closure devices using a modified "preclosure" technique for access site management after percutaneous aortic valve replacement (PAVR).

BACKGROUND

PAVR using a retrograde transfemoral approach has recently evolved to an endovascular alternative to open surgery in high-risk patients. However, large-bore femoral artery access is required, commonly demanding surgical closure and general anesthesia. A truly percutaneous intervention would be desirable to reduce procedural complexity and diminish the need of vascular surgery and general anaesthesia.

METHODS

After direct puncture of the common femoral artery, three conventional suture-mediated closure devices (6F Perclose) were deployed. The preloaded sutures were tied at the end of the procedure. If no immediate hemostasis was achieved, an additional device was deployed thereafter.

RESULTS

PAVR with percutaneous access site closure was attempted in 15 consecutive patients and could successfully be achieved in all patients allowing conscious sedation in all but three cases. Following complications occurred: one retroperitoneal bleeding caused by removal of the valve delivery sheath requiring surgical repair, as well as two cases of femoral and iliac artery dissection caused by delivery sheath introduction and treated by stenting and vascular surgery, respectively. Vascular surgery became only necessary due to total vessel occlusion after suture closure and remains the only closure-related complication. However, treatment led to recovery in all patients.

CONCLUSIONS

The modified "preclosure" technique is a feasible and safe method for hemostasis after PAVR improving procedural management and diminishing the need for general anesthesia.

Percutaneous aortic valve replacement

Aortic valve replacement can produce dramatic benefit in the setting of aortic stenosis. The potential for morbidity and mortality associated with thoracotomy, cardiopulmonary bypass, and aortotomy has fostered a search for alternatives. Early experience with transcatheter endovascular aortic valve implantation demonstrated feasibility and durability, but the procedure was difficult to reproduce. However, equipment, techniques, and experience have evolved rapidly. Balloon-expandable and self-expanding prostheses and percutaneous femoral artery and open left ventricular apical access have found favor, each with potential advantages and disadvantages. Procedural success rates and clinical outcomes continue to improve. Current studies suggest that morbidity and mortality are competitive in comparison to conventional surgery in selected high-risk patients.

Percutaneous and Minimally Invasive Valve Procedures

The incidence of valvular heart disease is expected to increase over the next several decades as a large proportion of the US demographic advances into the later decades of life. At the same time, the next several years can be anticipated to bring a broad transition of surgical therapy to minimally invasive (minithoracotomy and small port) access and the more gradual introduction of percutaneous approaches for the correction of valvular heart disease. Broad acceptance of these technologies will require careful and sometimes perplexing comparisons of the outcomes of these new technologies with existing standards of care. The validation of percutaneous techniques, in particular, will require the collaboration of cardiologists and cardiac surgeons in centers with excellent surgical and catheter experience and a commitment to trial participation. For the near term, percutaneous techniques will likely remain investigational and will be limited in use to patients considered to be high risk or to inoperable surgical candidates. Although current-generation devices and techniques require significant modification before widespread clinical use can be adopted, it must be expected that less invasive and even percutaneous valve therapies will likely have a major impact on the management of patients with valvular heart disease over the next several years.

Percutaneous Aortic Valve Replacement

Objective

To improve the outcome of percutaneous valve replacement in aortic stenosis endovascular resection of calcified aortic valves will be necessary. In this study different sealing methods were evaluated. The focus of this research was feasibility and mechanical functionality in human anatomy.

Methods

The aortic valve isolation chamber (AVIC) is a catheter-based system to seal the aortic valve during resection, and was installed antegrade and retrograde. Firstly, AVIC was inserted antegrade via the cardiac apex in human postmortem models (n = 2), and secondly in porcine in vivo models under extra corporeal circulation (n = 5). Endoscopic inspection of the valve was recorded. AVIC was installed via a port system through the descending aorta. Micro- and macropathologies were performed.

Results

AVIC transapical deployment in the two human models took 3 and 4 minutes respectively and 2.2 ± 1.3 minutes in average in the porcine model. From the descending aorta, the deployment took 9.3 ± 5.5 minutes. Fluoroscopy and macroscopy demonstrated sealed chambers. Microscopic and histologic analysis demonstrated no profound damages of the surrounding tissue.

Conclusion

This study demonstrates the feasibility of transapical and retrograde endovascular sealing of the aortic valve in vitro and in vivo in nonbeating hearts.

Catheter-based modification of heart valve diseases: from experimental to clinical application

Efforts to modify cardiac valve defects using catheter-based techniques are increasing at the present time. We present observations on cardiac valve morphology and disease and review the progress being made to address valve defects with these innovative methods. Some new procedures developed through animal experimentation have already been put to use in clinical practice, but the newness of these techniques and the small number of cases in which they have been applied to date precludes an evaluation of their long-term durability. Although at the present time cardiac surgery remains the standard for treating most cases of valve disease, in certain situations a catheter-based treatment might provide a reasonable alternative, even if only temporary, especially for individuals with serious disease who are not suitable candidates for surgery.

Aortic valve replacement in elderly patients: what are the limits?

PURPOSE OF REVIEW

Increased life expectancy has led to a growing elderly population frequently presenting with aortic stenosis. This review focuses on modalities of aortic valve replacement designed to cope with the risks from multiple co-morbidities prevalent in the elderly.

RECENT FINDINGS

Cardiac surgery is safe in octogenarians; very low risks are associated with aortic valve replacement. Good short-term and medium-term results are seen with early surgical intervention for aortic stenosis in the relatively asymptomatic patient. The benefits seen with minimally invasive surgery make it more acceptable. A hybrid approach that deploys a drug-eluting stent for concomitant moderate coronary artery disease has shown promising results. An extension of this concept is the percutaneous aortic valve implantation that offers hope to the nonsurgical candidate. A systematic approach of minimally invasive surgery in patients with prior coronary artery bypass grafting minimizes injury to grafts. Bioprosthetic tissue valves are the valves of choice in all the above interventions.

SUMMARY

Cardiac surgery is used increasingly for aortic stenosis in elderly patients. Current experiences in minimally invasive and percutaneous approaches have opened the doors to hybrid strategies, which may be the mainstay of treatment for older patients needing aortic valve replacements in the future.

State of the art percutaneous intervention for the treatment of valvular heart disease: a review of the current technologies and ongoing research in the field of percutaneous valve replacement and repair

Technical developments in valvular intervention culminated in the first percutaneous valve replacement in the pulmonary position (2000) followed by replacement in the aortic position (2002). More recently, with the proven feasibility of percutaneous mitral valve repair, interventional cardiologists and cardiothoracic surgeons have begun to develop a new subspecialty dedicated to the percutaneous treatment of valvular disease. This review describes the clinical status of the current field, the applicability and limitations of new technologies, and the upcoming devices that will soon reach Phase I clinical trials.

Transapical Aortic Valve Implantation: An Animal Feasibility Study

BACKGROUND

Percutaneous aortic valve implantation has recently been performed in nonsurgical patients with severe aortic stenosis. Retrograde valve delivery has been problematic because of the size of the delivery system and concomitant peripheral vascular disease. We investigated a minimally invasive approach through the left ventricular apex for antegrade placement of a device-deliverable valve.

METHODS

Transapical aortic valve implantation was performed using a 23-mm equine valve mounted on a stainless steel stent in 24 swine (weight range, 35 to 45 kg). A limited or full sternotomy approach was used to access the apex of the heart. The crimped valve was introduced through a sheath in the left ventricular apex. Fluoroscopy and echocardiography were used for guidance. Deployments were performed on the beating heart either with ventricular unloading using femoral extracorporeal circulation or rapid ventricular pacing.

RESULTS

All valves were successfully delivered at the selected target site with acceptable visualization of the noncalcified aortic annulus. Valve migration occurred during eight deployments (two distal and six retrograde) secondary to persistent cardiac output, unfavorable annular anatomy, and dislodgement by the delivery catheter. Exact positioning of the nonmigrated valves at the aortic annulus was examined by necropsy of all animals at the end of the procedures. Paravalvular leak was noted in 14 of 18 (77.8%) valves remaining in situ.

CONCLUSIONS

The transapical approach was used for the successful antegrade placement of a stented valve, obviating the technical problems associated with a large delivery system transiting the peripheral vascular system. Stent design contributing to paravalvular leak remains problematic.

[Percutaneous cardiac valve replacement: a review]

Surgery is no longer the only technique to replace a cardiac valve. New percutaneous procedures allow aortic or pulmonary valve implantation. Even if the feasibility of these procedures has been proved, cases reported are very rare and selected. This emergent technology is still at an early stage of development and new prospective studies will be necessary to evaluate these procedures correctly before concluding their clinical benefit. At this time surgery remains the gold standard in terms of cardiac valve replacement.

Surgery Insight: current advances in percutaneous heart valve replacement and repair

Several advances have been made in interventional cardiology, particularly in the field of valvular heart disease. Among the procedures for which technologies are available, percutaneous replacement of the pulmonary and aortic valves, and percutaneous repair of the mitral valve, via annuloplasty or the Alfieri method, are the best known. Along with the excitement generated by these new subspecialties, however, there has also been skepticism. In this article we focus on the current innovations that have been applied to the procedures in humans, and discuss the advantages and disadvantages of the different strategies.

[Interventional cardiology in 2005]

Drug-eluting stents have been shown to reduce the rate of restenosis significantly in all types of lesion, patient and clinical context without increasing thrombotic complications. Although their high cost limits the extent to which they can replace bare-metal stents, their use will increase inexorably in coming years. In addition to stents containing sirolimus and paclitaxel, which have already been approved, two additional drug-eluting stents have appeared on the market this year: one elutes tacrolimus and the other, ABT578 (a rapamycin analogue). Now that the restenosis rate has been dramatically reduced, the main limitations on percutaneous coronary intervention (PCI) stem from problematic lesions such as those at bifurcations and chronic total occlusions. Although these lesions can be tackled more often and more successfully than in the past, the results obtained are very different from those achieved with other types of lesion. With improvements in safety and long-term efficacy, the number of indications for PCI has expanded to include patients with multivessel disease, left main coronary artery disease, left ventricular dysfunction, and diabetes, conditions in which surgical revascularization was thought necessary only a few years ago. Acute coronary syndromes now make up an increasing proportion of indications for PCI, both in absolute and relative terms. One future challenge is the early identification and treatment of vulnerable plaques before they manifest clinically in the form of irreversible complications such as sudden death or acute myocardial infarction. The use of multislice computed tomography, such as 64-slice detector systems, has considerably increased the sensitivity, specificity, and positive and negative predictive values of diagnosis to around 90%, though diagnostic accuracy may be considerably less in patients with severe coronary calcification, stents, or cardiac arrhythmias. Although the technique is straightforward for patients, the image reconstruction process is time-consuming, few centers currently offer the technique, and radiation exposure is several times that with conventional invasive coronary angiography. It appears that the main application of the technique is in ruling out coronary disease in low-risk patients rather than being part of the diagnostic work-up in those with a high probability of coronary artery disease.