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Eur J Cardiothorac Surg 2007;31:7-8. doi:10.1016/j.ejcts.2006.11.003
Copyright © 2007, European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved
Editorials |
Department of Cardiovascular Surgery, Albert-Ludwigs-University of Freiburg, Germany
Received 4 November 2006; received in revised form 4 November 2006; accepted 5 November 2006.
* Corresponding author. (Email: friedhelm.beyersdorf{at}uniklinik-freiburg.de).
Modern surgical treatment for aortic valve disease has undergone significant improvements in all areas of this procedure including the surgical techniques, durability of bioprothetic valves, techniques for myocardial protection, extracorporeal circulation, intraoperative echocardiography, anaesthesia, postoperative intensive care, as well as significant reduction in intensive care and hospital stay. This has resulted in very acceptable mortality and morbidity rates in most centers, even in high-risk patients. The major risk factors today for open heart aortic valve procedures are the number of co-morbidities of the patients and not age per se.
Despite these very promising results after aortic valve replacement (AVR), preliminary data point out that there seems to be a significant number of patients with aortic valve disease who are not referred for surgical treatment. This non-referral might be related to (a) a subjective lack of symptoms of older patients who would like to avoid open heart surgery in general and/or (b) the assumption of family physicians or cardiologists of a prohibitive operative risk, especially in older patients with several severe co-morbidities.
Balloon aortic valvuloplasty had been used as an alternative approach to non-surgical candidates. However, this treatment was associated with a high mortality and especially morbidity rate and a high return of symptoms and restenosis within months of the procedure [1] and has been abandoned.
Eventually the emerging field of endovascular stenting and the technology of integrating bioprothetic valves into a stainless steel stent has let to the transcatheter approach for AVR. After the first catheter-based aortic valve implantation in animals in 1992 [2,3] and further series of animal studies [4], the first successful catheter-based human aortic valve implantation was described in 2002 by Cribier and coworkers [5].
In the following years, three approaches have evolved as potential access routes to the aortic valve: antegrade femoral venous route, retrograde arterial route and transapical route.
The antegrade femoral venous route has the advantage that it may allow passage of large-profile valved stents and an antegrade crossing of the aortic valve. However, the severe disadvantages include a long and tortuous route from the femoral vein to the aortic valve, necessity to cross and dilate the atrial septum and the need to cross the mitral valve with the potential to induce acute mitral insufficiency by pushing against the anterior mitral leaflet. In high-risk patients the latter is often associated with severe reduction in cardiac output due to the creation of a high-grade mitral valve insufficiency [6].
The retrograde arterial approach requires retrograde crossing of the stenotic aortic valve and is limited to a low-profile system (24F in diameter). Frequently it results in vascular trauma [6], especially in older patients with their high incidence of peripheral artery as well as atherosclerotic disease in the thoracic and abdominal aorta.
Under these circumstances, the transapical approach seems to offer many potential advantages including that the native valve is crossed in an antegrade fashion, it permits a shorter and stiffer delivery system for more precise positioning and placement of the stented bioprosthesis. In addition, the lateral minithoracotomy and the transapical approach has been used by our group and others for LVAD [7] and apico-aortic conduit implantations, both with and without extracorporeal circulation.
In this volume of the European Journal of Cardiothoracic Surgery, a very interesting paper by Ye and coworkers [8] is published describing the clinical and echocardiographic follow-up after 6 months of transapical transcatheter aortic valve replacement in their initial seven patients. This report is a follow-up study of their initial description using left minithoracotomy and the transapical approach for aortic valve implantation in the first patient [9] and their initial experience after 1 month using this approach [10].
In this most current report of the Vancouver group [8], data are presented about seven patients with symptomatic aortic valve stenosis with a mean age of 77 years who were deemed to be non-surgical candidates for AVR for various reasons (logistic EuroSCORE predicted a 30-day mortality of 31%). The authors have used the transapical transcatheter approach in these patients using fluoroscopy and transesophageal echocardiography during the procedure. After balloon predilatation, a 26 mm Cribier–Edwards equine pericardial trileaflet valve mounted on a slotted stainless steel stent was implanted during rapid ventricular pacing. The authors report that valve implantation was successful in all seven patients without intra-procedural mortalities or complications. During the first 30 days of post surgery, one patient died on day 12 due to pneumonia (30-day mortality rate of 14%). Two further patients died on days 51 and 85 from non-cardiac causes. Therefore, four patients completed the 6-month follow-up protocol. After 6 months, aortic valve area increased from 0.7 ± 0.3 cm2 to 1.5 ± 0.5 cm2 and the mean transaortic gradient was reduced from 32 ± 8 mmHg to 11 ± 8 mmHg. In addition none or trivial, mild, and moderate aortic regurgitation was observed in 4, 2 and 1 patients, respectively. No valve-related complications occurred during the follow-up period.
The authors are to be congratulated for this innovative and new approach for a very sick patient group and their strict reporting of data on their first patient [9], their first follow-up of a small case series after 1 month [10] and now after 6 months [8]. Nevertheless some questions remain including the preoperative low transaortic gradient (33 ± 8 mmHg) in patients with good left ventricular ejection fractions (49 ± 9%) and very low aortic valve areas (0.7 ± 0.3 cm2). In addition, the authors did not observe any problems with obstructions of coronary ostia in their series after the deployment of the stented valve and this needs of course further observations. They also reported a decrease in valve area between 1 and 6 months postoperatively from 1.8 to 1.5 cm2, which needs further investigations down the line. Even though most patients had a very high logistic EuroSCORE [8] three patients had a score below 11. The authors reported that the indication for the transapical approach in these patients were porcelain aorta, multiple strokes with dementia and end-stage lung disease and therefore clear candidates for this innovative approach [8]. However, careful selection is of utmost importance if a standard safe surgical procedure is not used.
Further potential complications of valved stents should also be mentioned including migration, paravalvular leakage, rhythm disturbances, valve dysfunction after compression and re-expansion, impairment of coronary flow, embolisation, unknown durability of collapsible and compressible valves as well as potential problems with the delivery system or with the closure of the left ventricular apex. Interestingly, there are already reports about device closure of the left or even right ventricular apex after valved stent implantation [11–14].
In summary, the recent report of Ye and coworkers [8] is an innovative approach in a fast moving field in search for less invasive treatment modalities for high-risk patients with severe aortic valve disease. Currently, mini-thoracotomy and transapical delivery of stented valves seems to be superior to other approaches in this field (femoral venous antegrade route or arterial retrograde route), because (a) it is independent of the peripheral vascular tree and its atherosclerotic diseases, (b) larger and stiffer delivery catheters can be used and thereby allowing more precise deployment of the valved stent, (c) it can be used with or without extracorporeal circulation and (d) conversion to conventional surgery is possible at all times.
References
This article has been cited by other articles:
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  R. H. Bombien, M. Appel, T. Attmann, G.-R. Klaws, M. Schunke, C. Hass, J. Cremer, and G. Lutter Percutaneous aortic valve replacement: gross anatomy and histological findings after transapical and endoluminal resection of human aortic valves in situ Eur. J. Cardiothorac. Surg., July 1, 2009; 36(1): 112 - 117. [Abstract] [Full Text] [PDF]
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 R. Quaden, T. Attmann, M. Schunke, D. Theisen-Kunde, J. Cremer, and G. Lutter Percutaneous aortic valve replacement: Endovascular resection of human aortic valves in situ. J. Thorac. Cardiovasc. Surg., May 1, 2008; 135(5): 1081 - 1086. [Abstract] [Full Text] [PDF]
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