Percutaneous and Minimally Invasive Valve Procedures

Transcatheter aortic valve implantation: first results from a multi-centre real-world registry

AIMS

Treatment of elderly symptomatic patients with severe aortic stenosis and co-morbidities is challenging. Transcatheter aortic valve interventions [balloon valvuloplasty and transcatheter aortic valve implantation (TAVI)] are evolving as alternative treatment options to surgical valve replacement. We report the first results of the prospective multi-centre German Transcatheter Aortic Valve Interventions-Registry.

METHODS AND RESULTS

Between January 2009 and December 2009, a total of 697 patients (81.4 ± 6.3 years, 44.2% males, and logistic EuroScore 20.5 ± 13.2%) underwent TAVI. Pre-operative aortic valve area was 0.6 ± 0.2 cm² with a mean transvalvular gradient of 48.7 ± 17.2 mmHg. Transcatheter aortic valve implantation was performed percutaneously in the majority of patients [666 (95.6%)]. Only 31 (4.4%) procedures were done surgically: 26 (3.7%) transapically and 5 (0.7%) transaortically. The Medtronic CoreValve™ prosthesis was used in 84.4%, whereas the Sapien Edwards™ prosthesis was used in the remaining cases. Technical success was achieved in 98.4% with a post-operative mean transaortic pressure gradient of 5.4 ± 6.2 mmHg. Any residual aortic regurgitation was observed in 72.4% of patients, with a significant aortic insufficiency (≥Grade III) in only 16 patients (2.3%). Complications included pericardial tamponade in 1.8% and stroke in 2.8% of patients. Permanent pacemaker implantation after TAVI became necessary in 39.3% of patients. In-hospital death rate was 8.2%, and the 30-day death rate 12.4%.

CONCLUSION

In this real-world registry of high-risk patients with aortic stenosis, TAVI had a high success rate and was associated with moderate in-hospital complications. However, careful patient selection and continued hospital selection seem crucial to maintain these results.

Percutaneous mitral valve repair: potential in heart failure management

As a large portion of the US demographic advances into the later decades of life, the incidence of valvular heart disease is expected to increase. Mitral regurgitation (MR) caused by primary valve abnormality (degenerative) or secondary to cardiomyopathy (functional) is an important cause of heart failure. Management of valvular heart disease is expected to account for a large segment of services provided to heart failure patients. Recent years have seen a transition from surgical therapy to minimally invasive techniques, specifically percutaneous approaches for the correction of heart valve disease. The double orifice technique of mitral valve repair using the MitraClip System (Abbott Vascular, Menlo Park, CA) is one of many percutaneous approaches to treat significant MR. This technique is effective in patients with both degenerative and functional MR, reducing MR severity and improving heart failure symptoms. Broad acceptance of this percutaneous technology requires collaboration among cardiologists and cardiac surgeons in centers with superior catheter experience and knowledge of echocardiography.

Early and midterm hemodynamics after aortic valve bypass (apicoaortic conduit) surgery

BACKGROUND

Aortic valve bypass (AVB [apicoaortic conduit]) relieves aortic stenosis (AS) by connecting the apex of the left ventricle to the descending thoracic aorta with a valved conduit. AVB is performed through a small left thoracotomy, without cardiopulmonary bypass, aortic cross-clamping, cardiac arrest, or debridement of the native aortic valve. Little is known about hemodynamics, including ventricular performance, relative conduit blood flow, and progression of native AS after AVB.

METHODS

Forty-seven very high risk patients underwent AVB for AS between 2003 and 2009. The mean age was 82 years. Predismissal and interval transthoracic quantitative two-dimensional and Doppler echocardiography was performed in a core laboratory.

RESULTS

No patient had obstruction of the native aortic valve or the conduit during follow-up. The AVB effectively relieved left ventricular outflow tract obstruction (average peak gradient across the conduit was 5.6 +/- 3.8 mm Hg). Native aortic valve stenosis did not progress after AVB (0.63 +/- 0.16 cm(2) before surgery to 0.7 +/- 0.24 cm(2) at latest follow-up more than 6 months; p = 0.16). Total stroke volume increased after AVB from 60 mL +/- 22 mL to 107 mL +/- 27 mL (p < 0.0001). Left ventricular outflow was distributed in a predictable fashion between the conduit and the native aortic valve, with 63% +/- 10% of the flow directed to the conduit. Relative conduit flow remained stable (68% +/- 8%) at latest follow-up more than 6 months (p = 0.17).

CONCLUSIONS

Aortic valve bypass effectively relieves the outflow tract obstruction of AS. Placement of an apical valved conduit halts the biologic progression of AS.

Percutaneous mitral valve repair: the beginning of the end or the end of the beginning?

The new percutaneous mitral valve repair techniques are at an early stage. Preliminary series show that they are feasible; however, they need to be further evaluated in comparison with contemporary treatment to accurately assess their efficiency. Potential applications may benefit high-risk patients after thorough evaluation.

Transcatheter aortic valve implantation: role of multimodality cardiac imaging

Current evidence based on more than 8000 high-risk patients with severe aortic stenosis has demonstrated that transcatheter aortic valve implantation (TAVI) is a feasible alternative to surgical aortic valve replacement in selected patients. Despite current promising results on hemodynamic and clinical improvements, there are several unresolved safety issues, such as the frequency of vascular complications, postprocedural paravalvular leak, atrioventricular heart block and stroke. Multimodality cardiac imaging may help to minimize these complications and may play a central role before (optimizing patient selection, selection of appropriate prosthesis size and anticipating the procedural approach), during and after TAVI (evaluating the immediate and long-term procedural results). This article reviews the state-of-the-art TAVI procedures and the role that multimodality cardiac imaging plays before, during and after TAVI.

[Transcatheter aortic valve implantation: surgeon's view]

BACKGROUND AND PURPOSE

The technology of catheter- based aortic valve implantation is a new, less invasive therapeutic option for patients with symptomatic high-grade aortic stenosis. The present paper aims to demonstrate that optimal therapy should be provided by a multidisciplinary team consisting of cardiac surgeons, cardiologists and cardioanesthesiologists in a hybrid suite.

PATIENTS AND METHODS

From June 2007 to April 2009, 234 patients have been treated by transcatheter aortic valve implantation through different access sites (n = 168 femoral artery, n = 56 left ventricular apex, n = 7 subclavian artery, n = 3 ascending aorta) at the German Heart Center Munich, Germany. An algorithm for the choice of the most appropriate access site for the individual patient was established.

RESULTS

The 30-day mortality was 11.2% in this high-risk patient cohort. A certain number of periprocedural complications required surgical management. There was a considerable clinical improvement of the patients 6 months after the procedure.

CONCLUSION

Integrating the new methods of aortic valve implantation into a cardiac surgery program, all kinds of surgical and interventional treatment options may be offered to the patient with aortic stenosis by one multidisciplinary team. A qualified and safe performance of transcatheter aortic valve implantation and the management of potential complications require the presence of a hybrid suite.

Survival after transapical and transfemoral aortic valve implantation: talking about two different patient populations

OBJECTIVE

Recently, suspicion had been expressed that survival might be impaired after antegrade transapical as opposed to retrograde transfemoral valve implantation in high-risk patients with aortic stenosis. We analyzed survival in patients undergoing transcatheter aortic valve implantation with special emphasis on the access site for implantation.

METHODS

Between June 2007 and February 2009, 203 high-risk patients (EuroSCORE, 22% +/- 14%; mean age, 81 +/- 7 years) underwent transcatheter aortic valve implantation via a transapical (n = 50) or transfemoral (n = 153) access. The transapical implantation technique was chosen only in patients who had no access through diseased femoral arteries.

RESULTS

Thirty-day survival was 88.8% after transfemoral versus 91.7% after transapical implantation (P = .918). The transapical group had a significantly higher preoperative brain natriuretic peptide value and a significantly higher incidence of peripheral vessel, cerebrovascular, and coronary heart disease. Death within 30 days was valve related in 25% (transapical) and 31% (transfemoral), cardiac in 25% and 13%, and noncardiac in 50% and 56%, respectively (no significant difference). Complications specific to the access site (peripheral vessel injury or apex complications) occurred in both groups, whereas neurologic events did not occur in the transapical group (P = .041).

CONCLUSIONS

Our patient and access site selection process, with the transfemoral technique considered the access site of first choice, results in comparable survival and morbidity for either transfemoral or transapical transcatheter aortic valve implantation. Both techniques are associated with certain access site-specific complications that require highly qualified management. The neurologic risk profile of the patients should be included in the decision-making process before transcatheter aortic valve implantation, inasmuch as neurologic events may be reduced with the transapical access.

Development and evaluation of a novel artificial catheter-deliverable prosthetic heart valve and method for in vitro testing

BACKGROUND

This work presents a novel artificial prosthetic heart valve designed to be catheter or percutaneously deliverable, and a method for in vitro testing of the device. The device is intended to create superior characteristics in comparison to tissue-based percutaneous valves.

METHODS

The percutaneous heart valve (PhV) was constructed from state-of-the-art polymers, metals and fabrics. It was tested hydrodynamically using a modified left heart simulator (Lhs) and statically using a tensile testing device.

RESULTS

The PhV exhibited a mean transvalvular pressure gradient of less than 15 mmhg and a mean regurgitant fraction of less than 5 percent. It also demonstrated a resistance to migration of up to 6 N and a resistance to crushing of up to 25 N at a diameter of 19 mm. The PhV was crimpable to less than 24 F and was delivered into the operating Lhs via a 24 F catheter.

CONCLUSION

An artificial PhV was designed and optimized, and an in vitro methodology was developed for testing the valve. The artificial PhV compared favorably to existing tissue-based PhVs. The in vitro test methods proved to be reliable and reproducible. The PhV design proved the feasibility of an artificial alternative to tissue based PhVs, which in their traditional open-heart implantable form are known to have limited in vivo durability.

Safety of percutaneous aortic valve insertion. A systematic review

Background

The technique of percutaneous aortic valve implantation (PAVI) for the treatment of severe aortic stenosis (AS) has been introduced in 2002. Since then, many thousands such devices have worldwide been implanted in patients at high risk for conventional surgery. The procedure related mortality associated with PAVI as reported in published case series is substantial, although the intervention has never been formally compared with standard surgery. The objective of this study was to assess the safety of PAVI, and to compare it with published data reporting the risk associated with conventional aortic valve replacement in high-risk subjects.

Methods

Studies published in peer reviewed journals and presented at international meetings were searched in major medical databases. Further data were obtained from dedicated websites and through contacts with manufacturers. The following data were extracted: patient characteristics, success rate of valve insertion, operative risk status, early and late all-cause mortality.

Results

The first PAVI has been performed in 2002. Because of procedural complexity, the original transvenous approach from 2004 on has been replaced by the transarterial and transapical routes. Data originating from nearly 2700 non-transvenous PAVIs were identified. In order to reduce the impact of technical refinements and the procedural learning curve, procedure related safety data from series starting recruitment in April 2007 or later (n = 1975) were focused on. One-month mortality rates range from 6.4 to 7.4% in transfemoral (TF) and 11.6 to 18.6% in transapical (TA) series. Observational data from surgical series in patients with a comparable predicted operative risk, indicate mortality rates that are similar to those in TF PAVI but substantially lower than in TA PAVI. From all identified PAVI series, 6-month mortality rates, reflecting both procedural risk and mortality related to underlying co-morbidities, range from 10.0-25.0% in TF and 26.1-42.8% in TA series. It is not known what the survival of these patients would have been, had they been treated medically or by conventional surgery.

Conclusion

Safety issues and short-term survival represent a major drawback for the implementation of PAVI, especially for the TA approach. Results from an ongoing randomised controlled trial (RCT) should be awaited before further using this technique in routine clinical practice. In the meantime, both for safety concerns and for ethical reasons, patients should only be subjected to PAVI within the boundaries of such an RCT.

Future of cardiac surgery: minimally invasive techniques in sutureless valve resection

Aortic valve replacement with mechanical or biological heart valves is the treatment of choice for aortic valve stenosis when it is symptomatic or with severe aortic stenosis (≤ 0.6 cm2/m2) or with left ventricular dysfunction. In an effort to improve the outcomes of patients with stented biological valves, stentless valves were introduced to clinical practices in the early 1990s. Theses valves were designed to be less obstructive, and thus result in a lower transvalvular gradient. Technically the implantations of these valves are more demanding resulting in longer cross clamp and bypass times. However, important comorbid conditions in elderly patients referred for aortic valve replacement require alternative treatment options with possible reductions of the extracorporeal bypass time and reliable hemodynamic features. In order to comply with these requirements, percutaneous valves and sutureless surgical valves have been developed. The percutaneous technique has the advantage of being performed without circulatory bypass but leaving the aortic calcifications in place, thereby resulting in a high degree of paravalvular insufficiency, atrioventricular block and strokes. The surgical approach has the advantage of removing all calcifications and the valves can be optimally implanted, resulting in minimal paravalvular leak with a low incidence of atrioventricular block and strokes; however, it requires cardiopulmonary bypass. In addition, it can be performed with a low mortality (<3% in isolated aortic replacement, even in older patients). This article reviews the various techniques, strength and limitations of these sutureless valves implanted in the aortic position.

Job Matters

Background— Percutaneous aortic valve replacement (PAVR) for aortic stenosis is an attractive alternative to operative valve replacement. Several devices are evaluated, but their efficacy and safety are critically discussed. An interdisciplinary approach with collaboration of cardiac surgeons and cardiologists is widely requested. We analyzed how cardiologists and cardiac surgeons assess the possibilities and risks of PAVR and whether there are substantial differences between the judgments of these 2 groups.

Methods and Results— Fifty-one cardiologists and 54 cardiac surgeons from German hospitals completed an online questionnaire consisting of 11 questions dealing with typical risks and benefits of PAVR. Answers to all questions differed significantly between surgeons and cardiologists. Risks as impaired hemodynamic outcome, paravalvular leakage, or embolic events were deemed higher for PAVR than for an operation from both groups, but cardiologists rated those risks significantly lower than cardiac surgeons ( P <0.01 for all questions). A regression analysis with a latent variable approach for possible advantages of PAVR (like minor operative trauma, faster recovery, less pain) showed that the fact of being a cardiologist has a significant impact on the rating of PAVR advantages ( r =0.719, P <0.01), whereas personal experience showed no significant effect.

Conclusions— Cardiologists and cardiac surgeons agree on possible risks and advantages of PAVR, but the extent differs significantly between the 2 groups. Cardiologists have a far more optimistic view of PAVR and are likely to favor an interventional approach. More and better evidence based information may help to overcome group related prejudices.

Comparison of heavier versus lighter operatively excised stenotic aortic valves in adults with aortic stenosis and implications for percutaneous aortic valve implantation without replacement

To better understand aortic valves amenable to percutaneous aortic valve implantation, operatively excised stenotic aortic valves were examined and divided into 2 groups: heavier and lighter valves. Among 2,247 operatively excised stenotic aortic valves in adults aged >20 years without associated mitral stenosis or mitral valve replacement, 1,608 valves were weighed; 1,241 (77%) weighed <4 g, and 367 (23%) weighed > or =4 g. Of the valves from 1,038 men, 717 (69%) weighed <4 g, and 321 (31%) weighed > or =4 g; of the valves from 570 women, 524 (92%) weighed <4 g, and 46 (8%) weighed > or =4 g. The patients with heavier (> or =4 g) valves had higher transvalvular peak gradients (78 +/- 28 vs 55 +/- 27 mm Hg, p <0.0001), smaller valve areas (0.69 +/- 0.30 vs 0.75 +/- 0.27 cm(2), p <0.0001), and more often congenitally malformed valves (327 of 367 [89%] vs 638 of 1,241 [51%], p <0.0001). In patients aged 81 to 90 years, 44 of the 195 valves (23%) were congenitally unicuspid or bicuspid; in those aged 41 to 50 years, 112 of 128 valves (88%) were congenitally malformed. In conclusion, compared with patients whose stenotic aortic valves weighed <4 g, those with valves weighing > or =4 g were younger, had higher transvalvular peak systolic pressure gradients, had smaller valve areas, and usually (about 90%) had congenitally unicuspid or bicuspid valves. It seems reasonable to avoid percutaneous aortic valve implantation in patients with heavily calcified stenotic aortic valves, most of which are either congenitally unicuspid or bicuspid.

Bone modifiers and the quest to slow progression of aortic stenosis

Aortic stenosis (AS) will likely become increasingly frequent with the aging of the American population. The difficulties in treating elderly patients with critical AS emphasize the potential value of a strategy to slow the advancement of aortic valve calcification. Recent prospective trials of statins and angiotensin-converting enzyme inhibitors have been disappointing. New options are needed to achieve a truly effective strategy for retarding the advancement of AS. In this context, the observations of Skolnick et al appearing in this issue of The American Journal of Cardiology are particularly intriguing. In a retrospective review of patients followed for mild or moderate AS, these investigators found that 18 patients receiving treatment for osteoporosis had significantly less decrement in aortic valve area on follow-up echocardiography than 37 not receiving such treatment. The most attractive explanation is an action of drug therapy for osteoporosis, most often bisphosphonates, to retard aortic valve calcification. The mechanism for this action is not clear, although numerous possibilities can be postulated on the basis of the multiple complex processes controlling tissue calcification. In conclusion, the investigators' findings deserve further study to clarify drug impact on aortic valve calcification as well as confirm the clinical findings in a larger and more diverse population. Such investigation should also assess the role of vitamin D and calcium supplementation, common features of treatment for osteoporosis. Currently available results are too preliminary to justify the use of bisphosphonates or other osteoporosis therapies to slow the progression of AS.

Valve implantation on the beating heart: catheter-assisted surgery for aortic stenosis

BACKGROUND

For an increasing number of patients with severe symptomatic aortic stenosis, advanced age and comorbidity make the risk of surgery unacceptably high. In such cases, catheter-based techniques for aortic valve implantation are a new therapeutic option. In this paper, we describe the initial results obtained at the German Heart Center, Munich, with a new technique of this kind.

METHODS

From June 2007 to September 2008, 152 patients underwent transcatheter aortic valve implantation at the German Heart Center, Munich (121 transfemorally, 26 transapically, and 5 through other sites of access). In this technique, a stent-mounted valve is crimped onto a catheter and then positioned and deployed in the aortic annulus under fluoroscopic control.

RESULTS

The 30-day mortality was 11.8% in this group of patients at high risk. The more common post-procedural complications were third-degree atrioventricular block leading to pacemaker implantation (31/152, 20%), vascular complications (25/152, 16%), and cerebrovascular events (8/152, 5%). Six months after the procedure, the patients had recovered clinically to a considerable extent, and the implanted prostheses exhibited good hemodynamic function.

CONCLUSIONS

The technical feasibility of catheter-based aortic valve implantation has been demonstrated at multiple centers around the world. Its indications still need to be refined on the basis of the short- and long-term results of the randomized and observational studies that are currently in progress. It is already apparent that catheter-based aortic valve implantation can bring about clinical improvement in patients who are deemed ineligible for open surgery.

[Update on interventional cardiology]

Percutaneous intervention, whether coronary or noncoronary, continues to be a highly active area of medicine. This article contains an overview of the most notable developments reported in recent months. Drug-eluting stents (DESs) have provided one of the major advances in interventional cardiology as they have very effectively reduced the restenosis rate. Both randomized clinical trials and large observational studies have confirmed their safety, and their use has been extended to include highly complex conditions. Although thrombosis is one complication that can affect both conventional stents and DESs, the rate of late stent thrombosis is slightly, though significantly, higher with DESs. Primary angioplasty is the treatment of choice for patients with acute myocardial infarction if carried out under appropriate conditions, within a reasonable time period in a specialized center by experienced personnel. Use of thrombectomy devices can improve procedural outcomes and it appears that DES implantation is safe and effective, though more data are still needed. In patients with non-ST-elevation acute coronary syndrome, early treatment using an invasive approach coupled to the administration of various combinations of antiplatelet and antithrombotic drugs continues to be fundamental. Although left main coronary artery lesions are generally treated surgically, advances in percutaneous techniques and the use of DESs mean that an increasing number of patients are being treated using percutaneous coronary interventions. A number of studies have shown good results in other lesions and in high-risk patients with, for example, bifurcation lesions, chronic occlusions or diabetes. Intracoronary ultrasound is the predominant intracoronary diagnostic technique and it can be used to assist in optimizing DES implantation. In addition, measurement of the fractional flow reserve is helpful in evaluating the severity of moderate lesions whereas the high-resolution images provided by optical coherence tomography are particularly informative. Multislice computed tomography enables the presence of coronary artery disease to be ruled out and the technique is also useful as a complementary tool for interventional cardiologists. Research into regenerative techniques is promising but remains experimental at present. With regard to noncoronary interventions, new data have become available that support the use of a percutaneous approach in patients with patent foramen ovale. In addition, clinical experience with percutaneous aortic valve replacement, via either the transfemoral or transapical route, is increasing.

Valvular regurgitation and stenosis: when is surgery required?

Valvular heart disease is a growing public health problem, with an increasing prevalence due to an ageing population. Despite advances, the medical management of symptomatic valvular heart diseases remains suboptimal, necessitating surgical correction. The challenge remains in identifying an asymptomatic or mildly symptomatic patient who will benefit from timely surgery before irreversible changes in cardiac function have occurred. The potential risks of surgery versus watchful expectancy require careful decision-making. This review is a focused update on the existing guidelines and identifies the knowledge gaps and avenues of future research in the management of patients with valvular heart diseases.

Transcatheter valve implantation for patients with aortic stenosis: a position statement from the European Association of Cardio-Thoracic Surgery (EACTS) and the European Society of Cardiology (ESC), in collaboration with the European Association of Percutaneous Cardiovascular Interventions (EAPCI)

AIMS

To critically review the available transcatheter aortic valve implantation techniques and their results, as well as propose recommendations for their use and development.

METHODS AND RESULTS

A committee of experts including European Association of Cardio-Thoracic Surgery and European Society of Cardiology representatives met to reach a consensus based on the analysis of the available data obtained with transcatheter aortic valve implantation and their own experience. The evidence suggests that this technique is feasible and provides haemodynamic and clinical improvement for up to 2 years in patients with severe symptomatic aortic stenosis at high risk or with contraindications for surgery. Questions remain mainly concerning safety and long-term durability, which have to be assessed. Surgeons and cardiologists working as a team should select candidates, perform the procedure, and assess the results. Today, the use of this technique should be restricted to high-risk patients or those with contraindications for surgery. However, this may be extended to lower risk patients if the initial promise holds to be true after careful evaluation.

CONCLUSION

Transcatheter aortic valve implantation is a promising technique, which may offer an alternative to conventional surgery for high-risk patients with aortic stenosis. Today, careful evaluation is needed to avoid the risk of uncontrolled diffusion.