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a Center for Aortic Surgery, Marfan Syndrome and Connective Tissue Disorders Clinic, and Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, Cleveland, Ohio
b Medical City Hospital, Dallas, Texas
c Columbia Presbyterian Medical Center, New York, New York
d Consultant, Lake Forest, California
Accepted for publication April 9, 2008.
* Address correspondence to Dr Svensson, Center for Aortic Surgery, Marfan and Connective Tissue Disorder Clinic, Department of Thoracic and Cardiovascular Surgery, Cleveland Clinic, 9500 Euclid Avenue, Desk F25, Cleveland, OH 44195 (Email: svenssl{at}ccf.org).
Presented at the Forty-fourth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2008.
| Drs Anderson, Dewey, Roselli, Smith, and Williams disclose that they have a financial relationship with Edwards Lifesciences.
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Abstract |
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Methods: Between December 2006 and February 18, 2008, 40 patients underwent transcatheter insertion of a balloon expandable stainless-steel stent with an internally mounted three-leaflet equine pericardial valve (Edwards Sapien Transcatheter Heart Valve; Edwards Lifesciences, Irvine, CA) into the aortic annulus using a transapical left ventricular insertion (TA-AVI). Patients were inoperable by conventional surgery, or extremely high risk based on Society of Thoracic Surgeons score greater than 15% or other documented risk factors.
Results: All 40 valves were successfully delivered and 35 were successfully seated. Two valves embolized and required open aortic valve replacement (AVR), and one case of severe regurgitation later required AVR. In a further two patients placed on cardiopulmonary support, one valve later embolized and one migrated. There were 7 (17.5%) deaths within 30 days, and a further 2 (5%) deaths before discharge at 42 and 72 days. There were no immediate postoperative strokes after successful deployment. Valve area improved from 0.62 cm2 (SD of 0.13) to 1.61 cm2 (SD 0.37) at 30 days (p = <0.0001), with mean perivalvular regurgitation of 1.19 (SD 0.80). Mean follow-up was 143 days (SD 166 days) with 6 further deaths from comorbid disease, none valve or cardiac related. The Kaplan-Meier survival was 81.8% ± 6.2% at 1 month and 71.7% ± 7.7% at 3 months.
Conclusions: Transapical insertion of a balloon expandable stented valve is feasible but carries considerable risk and will be further evaluated in the PARTNER (Placement of AoRTic traNscathetER valve) randomized trial.
In the realm of cardiovascular disease, there are few other disease entities that benefits as much from a cardiovascular procedure as symptomatic aortic stenosis [1–14]. Aortic valve replacement both improves quality of life by eliminating symptoms and by dramatically improving long-term survival. Yet, in a European study (Euro Heart Survey) [5], only 31.8% of patients underwent aortic valve replacement and even more disconcerting, in a study from Southern California [1, 2], 61% of patients with critical aortic stenosis, either symptomatic or asymptomatic (<0.8 cm2), never underwent aortic valve replacement. Clearly, with some 48,000 patients undergoing aortic valve replacement annually in the US, from a population of some 125,000 estimated patients with severe aortic valve stenosis [4], a large population of patients is not undergoing surgery because of various reasons. This is most probably because of comorbid disease in the elderly, with some 2.2% of elderly patients with critical aortic stenosis. The likelihood is that only one third of symptomatic patients will be alive by one year [6]. Alternative methods like balloon valvuloplasty and apico-descending valve conduits have been used with varying success for technically high-risk patients and have led to the search for alternative methods [15–26].
Based on the initial success of the study of Andersen and colleagues [15] in an animal model, a human percutaneous insertable valve was developed and later deployed by Cribier and colleagues [21, 22] in April 2002 through a transfemoral vein approach. Although this route was technically challenging, research by both Lichtenstein and colleagues [18] and Webb and colleagues [19] in Vancouver, Canada, and us [17] resulted in animal studies showing that a trans-left ventricular apex aortic valve insertion (TA-AVI) was feasible. The transapical approach was then used in two patients in Leipzig followed by conventional aortic valve replacement [16]. Subsequently, Lichtenstein and colleagues [18] successfully permanently inserted a transapical valve in a patient. Introduction of the TA-AVI procedure in the US was delayed by regulatory issues, and, in the mean time, a transfemoral aortic valve insertion (TF-AVI) approach, using a retrograde arterial approach, was pioneered by Webb's group in Canada [19]. This TF-AVI approach was then adopted in the US and the Food and Drug Administration (FDA) approved the percutaneous endovascular implantation of valves study (REVIVAL) at Columbia Medical Center, Cleveland Clinic, and William Beaumont hospitals for a total of 55 TF-AVI patients. After the completion of the REVIVAL study, the FDA approved a feasibility study of 20 patients in the US of the TA-AVI approach at Dallas Medical Center, Columbia Medical Center, and Cleveland Clinic. In late 2007, another 20 patients were approved for further study.
This manuscript reports our methods and outcomes for the US FDA approved TA-AVI feasibility study using the Edwards balloon expanded stainless-steel stent (Edwards Lifesciences, Irvine, CA) with xenograft leaflets, either equine or bovine pericardial leaflets.
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Patients and Methods |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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Myocardial infarction was classified as follows: Q-wave MI = development of new, pathological Q waves in 2 or more contiguous leads (as assessed by the ECG core laboratory) with CK or CK-MB levels elevated above normal; non-Q wave MI = elevation of CK to more than twice normal with elevated CK-MB. Major adverse cardiac and cerebrovascular events (MACCE) was defined as death, myocardial infarction (Q wave and non-Q wave), emergent cardiac surgery, valvular thrombosis, structural valve deterioration, and hemorrhagic or ischemic stroke.
Statistical Analysis
Standard methods for descriptive statistics have been used. The p values for comparison to baseline are computed using the two-sample t test. Standard errors for Kaplan-Meier analysis use the Greenwood algorithm, and for binary variables the exact confidence limits are used. Percentages reflect the actual denominators; for baseline variables the denominator is generally 40.
Operative Technique
All patients underwent extensive screening including the following: pulmonary function testing, computer tomography studies to study aortic and aortic valve calcium, arterial access, the possibility of calcium occluding coronary artery ostia, and cardiac catheterization to study coronary vascular anatomy and the nadir of valve sinuses. The nadir of the valve sinus was used to obtain the best fluoroscopy plane to visualize the low points of each sinus and to have all three nadir planes in alignment for valve placement.
The TA-AVI was performed in sterile operating conditions, mostly in hybrid fluoroscopy operating rooms. Early attempts to perform the procedure with mobile fluoroscopy units were abandoned. Double lumen intubation, general anesthesia, and transesophageal echocardiography were used in all patients. Cardiopulmonary bypass machines were available, and 10 patients required cardiopulmonary bypass because of intraoperative problems.
In all patients, the femoral vessels were exposed in case cardiopulmonary bypass was required. In addition, a pigtail catheter was inserted into the femoral artery for aortic root aortography and fluoroscopic imaging of the aortic valve leaflet nadirs. Either transfemoral venous or epicardial pacing leads were placed and tested at between 180 beats per minute to 220 beats per minute to check thresholds and for rapid pacing abolishing cardiac ejection.
An anterior sixth or fifth intercostal space minithoracotomy was performed to expose the left ventricular apex. The incision was determined by chest X-ray, palpation, and echocardiography. Two to three purse string sutures were then placed in the left ventricular apex using strong deep pledgeted Prolene sutures (Ethicon, Somerville, NJ), avoiding the left anterior descending artery. Apical epicardial echocardiography and transesophageal echocardiography were used to determine the best site for inserting the initial needle puncture and guide wires, with the aortic valve lined up with the axis of insertion. Care was taken to avoid the mitral subvalvular apparatus and displacement by the left ventricular outflow tract muscle bar.
After insertion of the ventricular wire through the needle, a Berman balloon catheter was inserted (Cleveland Clinic) or a guide wire was fed through the aortic valve and around the aortic arch. Exchange was made for an extra stiff guide wire to the renal arteries. This was inserted in order to maintain control of the stent valve device should it embolize during insertion and also to prevent it from tumbling and obstructing and occluding the descending aorta.
A 12-14 French sheath was then inserted over the guide wire and used for insertion of a 20 mm to 22 mm balloon for dilation of the native aortic valve. The critical sequences for both balloon valvuloplasty and stent valve insertion were the following: fluoroscopy on, cine on, holding of ventilation by anesthesia, rapid pacing to 180 beats per minute to 220 beats per minute, balloon insufflation when the pressure dropped to below 50 mm Hg, balloon deflation, balloon withdrawal, stopping pacing, cine off and then restarting patient ventilation. Balloon inflation for valvuloplasty was repeated until it was neither displaced "ventricular" nor "aortic" direction. The balloon positioning was checked with dilute contrast medium during fluoroscopy and by transesophageal echocardiography. Stent valve selections size was based on transesophageal diameter measurements at the valve hinge points. For 22 mm or less, a size 23 mm valve was selected and for larger diameters the 26 mm valve was selected. However, for a size larger than 24 mm, valve insertion was contraindicated because of the risk of dislodgement.
After successful balloon valvuloplasty, the balloon was withdrawn and exchanged for the large bore sheath (33 French gauge sheath in the first 20 patients and 26 Fr in the second 20) with internal dilator over the guide wire and the dilator withdrawn. The stainless-steel stent and valve device (Edwards Sapien Transcatheter Heart Valve; Edwards Lifesciences, Irvine, CA) was prepared by a technician on a back table and crimped onto the balloon and inserted into a loading connector. This preparatory process was confirmed by visual inspection by the operating team in every instance because a valve could easily be inserted backwards. The loading connector was then attached to the large sheath, the valve advanced into the sheath with a pusher catheter, air was removed, and then the stent valve advanced to the native aortic valve. Removal of air of the valve loading device is of critical importance. The pusher and sheath were withdrawn back into the apex and balloon clearance was checked by fluoroscopy.
The stent valve was centered on the valve hinge points using both fluoroscopy of calcium deposits on the valve, root aortography, and transesophageal echocardiography. On transesophageal echocardiography, this tended to be 60% "ventricular." Root contrast aortography, using the previously determined nadir plane of all three leaflets, was then used to check accurate positioning. A "dry run" of holding ventilation, rapid pacing, and checking for valve displacement was then performed to make sure that the valve did not move during the deployment sequence. When every member of the team agreed on positioning (surgeon, cardiologist, echocardiographer, and technicians) the deployment sequence was again commenced, and during rapid pacing of about 15 seconds to 25 seconds, and when the blood pressure fell no further with pacing and there was a pressure of less than 50 mm Hg, the balloon was inflated and the stent valve deployed. Immediately after deployment the deflated balloon was withdrawn from inside the stent valve and valve competence and perivalvular leaks were assessed for by echocardiography.
In those patients with a significant perivalvular leak, balloon inflation with an additional 0.5 cm3 to 1 cm3 was repeated. Larger volumes should not be used because this may excessively splay the aortic side of the stent, which is unrestricted, whereas the collar on the ventricular side prevents over expansion. Splaying of the stents can result in central valve regurgitation. After root aortography to check valve competence, the large bore sheath was withdrawn and the purse string sutures tied. If the patient was hypertensive, had a fragile ventricle or severe thinning, the purse string sutures were tied down during rapid pacing. One pleural chest tube was inserted and the patient closed.
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Results |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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In one patient, in whom the cine was automatically switched off and failed during the critical moment of deployment, the valve embolized distally shortly after deployment. Retrospective analysis revealed the valve became displaced during breath holding and pacing and it was situated too high within the native valve leaflets. This patient underwent successful open retrieval of the valve on the guide wire in the ascending aorta and open aortic valve insertion; however, he required prolonged ventilation and hospitalization for severe associated pulmonary disease.
In another patient, the valve embolized back into the ventricle and a second valve was deployed, but it also embolized. The patient was placed on cardiopulmonary bypass and cooled to 20° C, reoperated (previous coronary bypass), and the two valves retrieved by an open transseptal approach and an open valve replacement performed with a balloon in the arch because of a porcelain aorta. The patient suffered a severe stroke diagnosed on the second postoperative day but was discharged from hospital to home care. Another patient embolized the left main coronary artery during deployment but without the valve or leaflets obstructing left main flow, required extracorporeal membrane oxygenation and balloon pump. Two to three hours after insertion, during a period of asystole, the valve embolized back into the left ventricle and subsequently the patient died from heart infarction and failure on the fourth day after surgery.
There were seven 30-day deaths (17.5%; 7 of 40) and nine (22.5%; 9 of 40) in-hospital/30-day deaths (Table 2). There were 3 deaths on the day of the operation. Of note, 2 deaths were related to embolization or migration, 1 from failure of leaflet apposition, 1 from aortic dissection, and 1 from heart failure and multiple organ failure. The others were from predominantly noncardiac complications.
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Of the 71 patients referred to Medical City Hospital, 14.1% (n = 10) received a conventional open inserted valve and 21% (n = 15) TA-AVI or TF-AVI with no conventional operative patient deaths, and 13.3% mortality for TA-AVI or TF-AVI. For the 92 patients referred to the Cleveland Clinic, 20% (n = 19) had conventional open surgery with no operative deaths, 19.6% (n = 18) underwent TA-AVI or TF-AVI with 5% 30-day deaths, and 20% (n = 19) underwent balloon valvuloplasty with 4% mortality. The late survival by Kaplan-Meier analysis was best for conventional valves followed by TA-AVI or TF-AVI (Fig 2).
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Comment |
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TopAbstractIntroductionPatients and MethodsResultsCommentDiscussionReferences |
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Clinically, after successful insertion, patients showed remarkable improvement in New York Heart Association functional class, decrease in gradients, improved orifice area, improved quality of life and return to a better functional performance. Survival in this series, and in the European and Vancouver transapical series [16, 18, 19] with over 60% at one year, compares favorably with a reported survival of only approximately 30% in symptomatic patients with aortic valve stenosis, especially when the severe comorbid disease in these elderly patients is considered. Based on our data for patients referred for screening for percutaneous aortic valves (TA-AVI or TF-AVI), open conventional surgery is preferable if deemed feasible by experienced surgeons, with no deaths in our experience. The TA-AVI or TF-AVI nevertheless offer very good one-year survival in this high-risk group of patients and better survival than that of medical management or balloon valvuloplasty (Fig 2).
The current iteration of the valve device has undergone changes over time from an equine to bovine pericardial valve, and also an increased cuff height. The leaflet attachment to the stent posts is similar to other Edwards pericardial valves (Edwards Lifesciences). The current iteration of the valve has been in a pulse duplicator to 400 million cycles, approximately equal to 10.4 years. With the conventional inserted Edwards pericardial valves, for patients over 70 years of age, the Kaplan-Meier freedom from reoperation due to valve failure is 93% at 12 years and 70% at 20 years [9, 11]. In this same age group, the actual proportion of patients needing reoperation for valve failure is 2% at 12 years and 4% at 20 years. Whether the new Sapien valve will be as durable remains to be seen. With over 500 valve insertions, there have been no late leaflet failures. Furthermore, "valve-in-valve" has been used acutely by us in 2 patients (one TA-AVI and one TF-AVI) and would be a late option for failed valves.
The technique of TA-AVI requires particular attention to detail, especially with respect to positioning of the stent valve within the native valve. The accumulated experience has shown that the hinge points of the native leaflets are the most useful landmark for positioning. This is also the site where the width of the annulus is measured by transesophageal echocardiography, even though the native leaflet is not perfectly planar or circular but oval, as seen by computed tomographic (CT) angiography. The CT angiography is helpful in evaluating the root for calcium, potentially blocking the coronary ostia or displacing the inflation balloon, such as a circumferential calcium bar at the sinotubular junction, which was implicated in causing embolization or migration in 3 patients. On retrospective careful review of cines and open surgical findings, in the one patient in whom 2 valves were placed, it was found that a concentric band of solid boney calcium at the sinotubular junction probably resulted in prevention of expansion of the deploying balloon and "watermelon seeding" of the valve in a "ventricular" direction. This resulted in embolization of the valves into the left ventricle.
The TA-AVI approach has most frequently been used for patients who lack an adequate femoral artery access. Indeed, patients with peripheral vascular disease have a greater risk of stroke and death either after conventional primary valve open replacement or after reoperative valve replacement [25]. This may negatively bias results with TA-AVI when patients with poor access are chosen for TA-AVI rather than TF-AVI. Conversely, TA-AVI, using a mini left anterior thoracotomy, may also be too invasive in some patients on high flow rates of home oxygen for chronic lung disease.
In the present study, the second series of patients appeared to do worse, but not significantly so, than the initial series, including 3 intraoperative deaths occurring in the second series. Furthermore, the results were not as good as those reported from Europe. There are several potential reasons for this. In the second series, most were patients who were not candidates for TF-AVI and the PARTNER study, largely because of ileofemoral artery access problems and peripheral vascular disease. Thus, there were more females because they were more frequently excluded from the TF-AVI PARTNER study. Patients with a porcelain aorta were more frequent because these patients also often had poor iliac artery access. There were also technical reasons for exclusion from TF-AVI such as bicuspid aortic valves, unfurled or ectatic aorta, and arch atherosclerosis. Indeed, patients included in TA-AVI had to have a higher STS score (>15% vs >10%) and a smaller aortic valve orifice area (0.6 cm2 vs 0.7 cm2). Moreover, 47.5% had previously undergone coronary artery bypass surgery and 45% had undergone percutaneous coronary interventions. The long period between completing the first series in April 2007 and then restarting again in October 2007 undoubtedly also contributed to the lack of continued improvement because the teams had to relearn the flow of the operation, and some of the personnel had changed. In comparison to the European series, it is noteworthy that the EuroSCORE in the present series was 36.6% versus 27% for the European series [16]. Of note, the European series has shown that the second series of patients did better than the initial series of patients, and this can be partly be attributed to the study not being interrupted. There is clearly a learning curve associated with the procedure. As with the European series, the risk of stroke was low and indeed none occurred early after successful deployment, suggesting this maybe a safer approach as far as stroke risk when compared to TF-AVI (9.2% in REVIVAL).
The limitation of this study is that this is an early feasibility study and thus no fair comparisons can be made to conventional open surgical replacement, balloon valvuloplasty, or best medical treatment. Nevertheless, TA-AVI patients will be enrolled in the FDA-approved current PARTNER high-risk surgical arm. Thus, TA-AVI patients will be randomly compared to high-risk surgery.
In conclusion, this feasibility study is encouraging. This new method may offer previously untreated patients or turned-down patients a new avenue of treatment provided procedural difficulties can be overcome.
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Discussion |
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I have no financial disclosures. However, I am a participant in the femoral approach to transcatheter AVR [aortic valve replacement] in the PARTNER trial. I receive no financial compensation for doing so.
I would like to provide the following comments and questions for Dr Svensson. The data clearly show a high-risk profile for these patients. The mortality at 30 days was 6 of 34, or 17.6%, 18 of whom were considered operable and 16 were considered inoperable. We know that the predicted mortality for the operable patients was higher (14.4%) than the inoperable patients, because several of the inoperable patients did not meet the 10% predicted risk of mortality criterion. So one could ask the question, what was the actual mortality in the 18 operable patients? In other words, how many out of those 6 patients that died within the first 30 days were operable and how many were inoperable?
In addition, it appears that, with respect to the immediate procedural success rate, there was a higher success rate seen in the first 20 patients than in the second group of 14 patients. Was there some change in the operative strategy, technique, or operator roles during that time that would accounted for that change. I would have expected a learning curve improvement over time.
Addressing procedural hemodynamics, 10 of the 34 patients required cardiopulmonary bypass, so I ask whether you have some comments of why that number was so high. Do you believe that the predilation strategy impacts significantly on the hemodynamics? In effect, if the annulus is not predilated adequately, does this increase the risk of hemodynamic instability postimplantation? To this point, would you comment on the valve sizing and on how that has a role in the postimplantation response?
Renal failure appeared to play a contributory role in a significant number of the adverse events. How much dye was used and what was the preoperative renal function in these patients.
Half the patients experienced a major adverse cardiac event, death, stroke, myocardial infarction, need for an open AVR, approximately two-thirds of the patients experienced adverse events, and 15 of these patients had device-related adverse events. It would be important to know in this early stage of investigation, precisely how many patients at 6 months have actually benefited from the procedure? Alternately stated, how many patients were free of MACCE [major adverse cardiac and cerebrovascular events], thriving with improved symptoms and quality of life?
I commend the centers for their excellent work and my congratulations to Dr Svensson for an outstanding presentation. Thank you.
DR SVENSSON: Thank you for your comments. As I explained, the patients who were inoperable obviously did not have necessarily a high STS [Society of Thoracic Surgeons] score, and that is clearly because those patients normally wouldn't be entered into the database because they wouldn't have had surgery. So, for example, a patient with Child's B cirrhosis or an extensive porcelain aorta or for other comorbid reasons may not be operated, that patient would never have been entered into the database, and therefore we would not have an appropriate calculated STS score on those patients. There were also some patients who were excluded from having a conventional open operation because of technical reasons that did not allow for a safe operation.
As far as looking at the outcomes in the patients who were potentially high risk but operable with an STS score of 15, I don't have that data broken down because the series is fairly small at this stage, nor have we looked at it. However, that will be answered now in the randomized study, because the patients will be randomized to high-risk surgery or transapical approach. So we hope to answer that question down the road.
As far as the early versus late results, when we include the total series of 36 patients there is no major difference between the early series and the late series. However, I will make a comment that the 6 months of downtime did affect our results I think in the sense that we had to relearn the procedure and we had a change in staffing from both the technical side and the nursing staff. We also had to reestablish the flow and rhythm of the operation, and I think that did set us back. If you look at the Leipzig series, there clearly is improvement in their second series versus their early series, and hopefully once we get going now and keep up the rhythm, we will continue to have good results. I would also point out that in the second series of patients, the patients were patients who could not be included in the transfemoral approach, and therefore these latter patients, in a sense, had been screened out to be too high risk, for various reasons, for the transfemoral approach.
As far as cardiopulmonary bypass, we decided right from the beginning that if we had even any minor hemodynamic problems we would put patients on pumps. We routinely either put wires into the femoral artery and vein for the procedure or at the Cleveland Clinic we routinely exposed the femoral artery and vein so we could immediately put the patients on pump; for example, if there was a problem with seating of the valve.
Renal function certainly was a problem after the procedure, but remember most of these patients to get to an STS score of 15 essentially have to have severe lung disease, they had to have renal dysfunction, diabetes, and be very elderly. Those comorbid factors come into play in increasing the risk of doing this procedure. Indeed, we actually tend to use less dye for the transapical approach when compared to the transfemoral approach.
As far as the MACCE events, I think I covered a lot of those. Many of them (10) were related to CPK leakage without the diagnosis of STEMI [ST-elevation myocardial infarct]/Q wave infarction based on the a priori definition of myocardial infarction. The enzyme level thresholds I believe were set too low and furthermore were not based on CK[creatine kinase]-MB or troponin levels.
There certainly is a learning curve to this procedure and hopefully we will reduce the incidence of complications. What is gratifying, at least in this series and also in the Leipzig series, is that the incidence of early stroke has been very low, and this I believe will be an advantage with this approach. Thank you for your questions.
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M. R. Reynolds, E. A. Magnuson, Y. Lei, M. B. Leon, C. R. Smith, L. G. Svensson, J. G. Webb, V. C. Babaliaros, B. S. Bowers, W. F. Fearon, et al. Health-Related Quality of Life After Transcatheter Aortic Valve Replacement in Inoperable Patients With Severe Aortic Stenosis Circulation, November 1, 2011; 124(18): 1964 - 1972. [Abstract] [Full Text] [PDF]
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J. Dunning, H. Gao, J. Chambers, N. Moat, G. Murphy, D. Pagano, S. Ray, J. Roxburgh, and B. Bridgewater Aortic valve surgery: Marked increases in volume and significant decreases in mechanical valve use--an analysis of 41,227 patients over 5 years from the Society for Cardiothoracic Surgery in Great Britain and Ireland National database J. Thorac. Cardiovasc. Surg., October 1, 2011; 142(4): 776 - 782.e3. [Abstract] [Full Text] [PDF]
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J. Kempfert, A. Rastan, D. Holzhey, A. Linke, G. Schuler, A. van Linden, J. Blumenstein, F. W. Mohr, and T. Walther Transapical Aortic Valve Implantation: Analysis of Risk Factors and Learning Experience in 299 Patients Circulation, September 13, 2011; 124(11_suppl_1): S124 - S129. [Abstract] [Full Text] [PDF]
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J. Higgins, J. Ye, K. H. Humphries, A. Cheung, D. A. Wood, J. G. Webb, and S. V. Lichtenstein Early clinical outcomes after transapical aortic valve implantation: A propensity-matched comparison with conventional aortic valve replacement J. Thorac. Cardiovasc. Surg., August 1, 2011; 142(2): e47 - e52. [Abstract] [Full Text] [PDF]
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S. Bleiziffer, N. Piazza, D. Mazzitelli, A. Opitz, R. Bauernschmitt, and R. Lange Apical-access-related complications associated with trans-catheter aortic valve implantation Eur J Cardiothorac Surg, August 1, 2011; 40(2): 469 - 474. [Abstract] [Full Text] [PDF]
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M. Thomas, G. Schymik, T. Walther, D. Himbert, T. Lefevre, H. Treede, H. Eggebrecht, P. Rubino, A. Colombo, R. Lange, et al. One-Year Outcomes of Cohort 1 in the Edwards SAPIEN Aortic Bioprosthesis European Outcome (SOURCE) Registry: The European Registry of Transcatheter Aortic Valve Implantation Using the Edwards SAPIEN Valve Circulation, July 26, 2011; 124(4): 425 - 433. [Abstract] [Full Text] [PDF]
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K. A. Horvath, D. Mazilu, O. Kocaturk, and M. Li Transapical aortic valve replacement under real-time magnetic resonance imaging guidance: experimental results with balloon-expandable and self-expanding stents Eur J Cardiothorac Surg, June 1, 2011; 39(6): 822 - 828. [Abstract] [Full Text] [PDF]
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G. Bruschi, F. De Marco, P. Fratto, J. Oreglia, P. Colombo, L. Botta, S. Klugmann, and L. Martinelli Alternative approaches for trans-catheter self-expanding aortic bioprosthetic valves implantation: single-center experience Eur J Cardiothorac Surg, June 1, 2011; 39(6): e151 - e158. [Abstract] [Full Text] [PDF]
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V. Falk, T. Walther, E. Schwammenthal, J. Strauch, D. Aicher, T. Wahlers, J. Schafers, A. Linke, and F. W. Mohr Transapical aortic valve implantation with a self-expanding anatomically oriented valve Eur. Heart J., April 1, 2011; 32(7): 878 - 887. [Abstract] [Full Text] [PDF]
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M. B. Leon, N. Piazza, E. Nikolsky, E. H. Blackstone, D. E. Cutlip, A. P. Kappetein, M. W. Krucoff, M. Mack, R. Mehran, C. Miller, et al. Standardized endpoint definitions for transcatheter aortic valve implantation clinical trials: a consensus report from the Valve Academic Research Consortium Eur. Heart J., January 6, 2011; (2011) ehq406v2. [Abstract] [Full Text] [PDF]
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J. Webb and A. Cribier Percutaneous transarterial aortic valve implantation: what do we know? Eur. Heart J., January 2, 2011; 32(2): 140 - 147. [Abstract] [Full Text] [PDF]
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L. G. Svensson Percutaneous aortic valves: Effective in inoperable patients, what price in high-risk patients? J. Thorac. Cardiovasc. Surg., December 1, 2010; 140(6_suppl): S10 - S13. [Full Text] [PDF]
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S. Geisbusch, S. Bleiziffer, D. Mazzitelli, H. Ruge, R. Bauernschmitt, and R. Lange Incidence and Management of CoreValve Dislocation During Transcatheter Aortic Valve Implantation Circ Cardiovasc Interv, December 1, 2010; 3(6): 531 - 536. [Abstract] [Full Text] [PDF]
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A. Vahanian, D. Himbert, and E. Brochet Transcatheter valve implantation for patients with aortic stenosis Heart, November 1, 2010; 96(22): 1849 - 1856. [Full Text] [PDF]
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E. E. Roselli, E. G. Soltesz, T. Mastracci, L. G. Svensson, and B. W. Lytle Antegrade Delivery of Stent Grafts to Treat Complex Thoracic Aortic Disease Ann. Thorac. Surg., August 1, 2010; 90(2): 539 - 546. [Abstract] [Full Text] [PDF]
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A. S. Petronio, M. De Carlo, F. Bedogni, A. Marzocchi, S. Klugmann, F. Maisano, A. Ramondo, G. P. Ussia, F. Ettori, A. Poli, et al. Safety and Efficacy of the Subclavian Approach for Transcatheter Aortic Valve Implantation With the CoreValve Revalving System Circ Cardiovasc Interv, August 1, 2010; 3(4): 359 - 366. [Abstract] [Full Text] [PDF]
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E. M. Tuzcu, S. R. Kapadia, and L. G. Svensson "SOURCE" of Enthusiasm for Transcatheter Aortic Valve Implantation Circulation, July 6, 2010; 122(1): 8 - 10. [Full Text] [PDF]
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M. Thomas, G. Schymik, T. Walther, D. Himbert, T. Lefevre, H. Treede, H. Eggebrecht, P. Rubino, I. Michev, R. Lange, et al. Thirty-Day Results of the SAPIEN Aortic Bioprosthesis European Outcome (SOURCE) Registry: A European Registry of Transcatheter Aortic Valve Implantation Using the Edwards SAPIEN Valve Circulation, July 6, 2010; 122(1): 62 - 69. [Abstract] [Full Text] [PDF]
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A. N. Azadani, N. Jaussaud, P. B. Matthews, L. Ge, T. A. M. Chuter, and E. E. Tseng Transcatheter aortic valves inadequately relieve stenosis in small degenerated bioprostheses Interact CardioVasc Thorac Surg, July 1, 2010; 11(1): 70 - 77. [Abstract] [Full Text] [PDF]
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J. Kempfert, A. Van Linden, A. Linke, M. A. Borger, A. Rastan, C. Mukherjee, J. Ender, G. Schuler, F. W. Mohr, and T. Walther Transapical Off-Pump Valve-in-Valve Implantation in Patients With Degenerated Aortic Xenografts Ann. Thorac. Surg., June 1, 2010; 89(6): 1934 - 1941. [Abstract] [Full Text] [PDF]
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T. D. Yan, C. Cao, J. Martens-Nielsen, R. Padang, M. Ng, M. P. Vallely, and P. G. Bannon Transcatheter aortic valve implantation for high-risk patients with severe aortic stenosis: A systematic review J. Thorac. Cardiovasc. Surg., June 1, 2010; 139(6): 1519 - 1528. [Abstract] [Full Text] [PDF]
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T. M. Dewey, D. L. Brown, M. A. Herbert, D. Culica, C. R. Smith, M. B. Leon, L. G. Svensson, M. Tuzcu, J. G. Webb, A. Cribier, et al. Effect of Concomitant Coronary Artery Disease on Procedural and Late Outcomes of Transcatheter Aortic Valve Implantation Ann. Thorac. Surg., March 1, 2010; 89(3): 758 - 767. [Abstract] [Full Text] [PDF]
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 J. G. Webb and F. Nietlispach Chapter 39 Transcatheter aortic valve replacement Oxford Textbook of Interventional Cardiology, January 1, 2010; 1(1): med-9780199569083-chapter - med-9780199569083-chapter. [Abstract] [Full Text]
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A. N. Azadani, N. Jaussaud, P. B. Matthews, L. Ge, T. S. Guy, T. A.M. Chuter, and E. E. Tseng Energy Loss Due to Paravalvular Leak With Transcatheter Aortic Valve Implantation Ann. Thorac. Surg., December 1, 2009; 88(6): 1857 - 1863. [Abstract] [Full Text] [PDF]
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 A. A. Klein, S. T. Webb, S. Tsui, C. Sudarshan, L. Shapiro, and C. Densem Transcatheter aortic valve insertion: anaesthetic implications of emerging new technology Br. J. Anaesth., December 1, 2009; 103(6): 792 - 799. [Abstract] [Full Text] [PDF]
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S. Bleiziffer, H. Ruge, D. Mazzitelli, A. Hutter, A. Opitz, R. Bauernschmitt, and R. Lange Survival after transapical and transfemoral aortic valve implantation: Talking about two different patient populations J. Thorac. Cardiovasc. Surg., November 1, 2009; 138(5): 1073 - 1080. [Abstract] [Full Text] [PDF]
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A.-P. Kappetein, N. Piazza, J.-C. Laborde, P. P. de Jaegere, and P. W. Serruys Transapical implantation of a self-expanding aortic valve bioprosthesis -- animal feasibility study Eur J Cardiothorac Surg, November 1, 2009; 36(5): 813 - 817. [Abstract] [Full Text] [PDF]
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S. Salizzoni, P. Bajona, K. J. Zehr, W. D. Anderson, S. Vandenberghe, and G. Speziali Transapical off-pump removal of the native aortic valve: a proof-of-concept animal study. J. Thorac. Cardiovasc. Surg., August 1, 2009; 138(2): 468 - 473. [Abstract] [Full Text] [PDF]
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H. Gasparovic Prosthesis-Patient Mismatch in the Elderly Ann. Thorac. Surg., August 1, 2009; 88(2): 709 - 710. [Full Text] [PDF]
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T. Walther, V. Falk, M. A. Borger, J. Kempfert, J. Ender, A. Linke, G. Schuler, and F. W. Mohr Transapical aortic valve implantation in patients requiring redo surgery Eur J Cardiothorac Surg, August 1, 2009; 36(2): 231 - 235. [Abstract] [Full Text] [PDF]
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N. Al-Attar, W. Ghodbane, D. Himbert, C. Rau, R. Raffoul, D. Messika-Zeitoun, E. Brochet, A. Vahanian, and P. Nataf Unexpected Complications of Transapical Aortic Valve Implantation Ann. Thorac. Surg., July 1, 2009; 88(1): 90 - 94. [Abstract] [Full Text] [PDF]
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 F. Aregger, P. Wenaweser, G. J. Hellige, A. Kadner, T. Carrel, S. Windecker, and F. J. Frey Risk of acute kidney injury in patients with severe aortic valve stenosis undergoing transcatheter valve replacement Nephrol. Dial. Transplant., July 1, 2009; 24(7): 2175 - 2179. [Abstract] [Full Text] [PDF]
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J. G. Webb, L. Altwegg, R. H. Boone, A. Cheung, J. Ye, S. Lichtenstein, M. Lee, J. B. Masson, C. Thompson, R. Moss, et al. Transcatheter Aortic Valve Implantation: Impact on Clinical and Valve-Related Outcomes Circulation, June 16, 2009; 119(23): 3009 - 3016. [Abstract] [Full Text] [PDF]
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V. Kurra, P. Schoenhagen, E. E. Roselli, S. R. Kapadia, E. M. Tuzcu, R. Greenberg, M. Akhtar, M. Y. Desai, S. D. Flamm, S. S. Halliburton, et al. Prevalence of significant peripheral artery disease in patients evaluated for percutaneous aortic valve insertion: Preprocedural assessment with multidetector computed tomography. J. Thorac. Cardiovasc. Surg., May 1, 2009; 137(5): 1258 - 1264. [Abstract] [Full Text] [PDF]
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 F. T. Billings IV, S. K. Kodali, and J. S. Shanewise Transcatheter Aortic Valve Implantation: Anesthetic Considerations Anesth. Analg., May 1, 2009; 108(5): 1453 - 1462. [Abstract] [Full Text] [PDF]
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 A. Vahanian, B. Iung, L. Pierard, R. Dion, and J. Pepper CHAPTER 21 Valvular Heart Disease ESC Textbook of Cardiovascular Medicine, January 1, 2009; 2(1): med-9780199566990-chapter - med-9780199566990-chapter. [Abstract] [Full Text] [PDF]
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H. C. Herrmann Transcatheter Aortic Valve Implantation: Past, Present, and Future Circ Cardiovasc Interv, December 1, 2008; 1(3): 159 - 160. [Full Text] [PDF]
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 L. G. SVENSSON Evolution and results of aortic valve surgery, and a 'disruptive' technology Cleveland Clinic Journal of Medicine, November 1, 2008; 75(11): 802 - 804. [Full Text] [PDF]
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