HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Goldman, B. S. Articles by Petracek, M. R. Search for Related Content PubMed PubMed Citation Articles by Goldman, B. S. Articles by Petracek, M. R. Related Collections Valve disease

Ann Thorac Surg 2001;71:S302-S305
© 2001 The Society of Thoracic Surgeons

---

Bioprosthetic valves and conduits: new developments

Clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve

^a Sunnybrook and Women’s College Health Sciences Centre, Toronto, Ontario, Canada

Address reprint requests to Dr Bernard S. Goldman, Sunnybrook and Women’s College Health Sciences Centre, 2075 Bayview Ave, H410, Toronto, ON, M4N 3M5, Canada
e-mail: bernard.goldman{at}swchsc.on.ca

Presented at the VIII International Symposium on Cardiac Bioprostheses, Cancun, Mexico, Nov 3–5, 2000.

	Abstract

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Background. Hemodynamic benefits of the Toronto stentless porcine valve have been documented. Clinical well-being and freedom from major valve-related events have been less well defined.

Methods. A total of 447 patients were prospectively followed for up to 8 years (1,745.2 valve years total, 3.9 valve years/patient). The patient demographics included 66% men, mean age 65 years, New York Heart Association functional class III–IV 55%, concomitant coronary artery bypass grafting 41%.

Results. We found that 83.7% of patients were in New York Heart Association functional class I and 80.8% had 0 to 1+ aortic insufficiency. Mean gradient at 6 years (n = 75) was 4.4 mm Hg and mean effective orifice area (EOA) 2.4 cm². Late adverse event rates per patient per year were: embolism 1.0%, endocarditis 0.4%, thrombosis 0%, structural deterioration 0.2%, explant 0.3%, and valve-related death 0.6%. Freedom from valve-related death at 6 years was 95.8%; from cardiac death 96.3%. Freedom from endocarditis was 98.4%, from embolism 93.9%, from structural deterioration 97.4%, and freedom from explant 98.1%. For patients older than 60 years, freedom from structural deterioration was 100%.

Conclusions. These results confirm satisfactory clinical outcomes after aortic valve replacement with the Toronto stentless porcine valve, with a low incidence of valve-related adverse events as long as 96 months after valve replacement.

	Introduction

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
The first clinical implants of the Toronto stentless porcine valve (TSPV) manufactured by St. Jude Medical (St. Paul, MN) occurred in July 1991; nearly a decade of clinical experience has since accumulated. The early hemodynamic characteristics have been described [1] and are comparable to cryopreserved allografts [2]. Medium-term follow-up (5 to 10 years) has demonstrated excellent continued function and suggested the potential for satisfactory durability [3, 4]. Although patient well-being has been reported as improved and maintained, little emphasis has been placed on clinical events during follow-up [5, 6]. Clinical outcomes after valve operations are related not only to the type of prosthesis implanted, but also to the cardiac status and other comorbidities present in the patient. In this study, we examined the clinical events and significant outcomes of 447 patients with the TSPV followed for almost 9 years.

	Material and methods

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Patients were enrolled in a multicenter, prospective, observational clinical trial from six Investigational Device Exemption sites (see Appendix) supported by the manufacturer and followed after approval and market release, as mandated by the US Food and Drug Administration.

The preoperative clinical characteristics of the patient cohort are described in Table 1. Of the 447 patients, 75.8% had a calcified valve, and 70.7% were stenotic.

	Results

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Operative data
Operative data has been reported previously [3]. Concomitant coronary artery bypass grafting was performed in 41.4% of patients. Valve sizes of 25, 27, or 29 mm were implanted in 82.5% of patients. No intraoperative complications were recorded in 93.3% of patients.

Hemodynamics
The echocardiographic findings during follow-up (5 to 6 years) have been described elsewhere [2, 3]. The mean gradient for all valve sizes at 6 years (n = 75) was 4.4 mm Hg and the mean EOA was 2.4 cm². The mean (± SD) left ventricular mass index at hospital discharge was 151.4 ± 49.8 g/m² (n = 404) and at 7 years (n = 23) was 124.4 ± 33.4 g/m². At 7 years, 80.8% of patients had no (0) or trivial (1+) aortic insufficiency (AI) compared with 88.3% at hospital discharge.

Clinical outcome
At the time of this report, 96 patients had reached 6 years postoperative and 43 patients had reached 7 years postoperative. Of the 447 patients, 365 were active, 49 were dead, 30 were lost to follow-up, and 7 had undergone explantation.

Although 55.0% of patients were in New York Heart Association (NYHA) functional class III–IV before operation, at 7 years 83.7% were in class I and 14.0% were in class II. Only 6.8% of patients were taking warfarin (Coumadin), usually for atrial fibrillation, and 72.7% of patients were on antiplatelet therapy, usually aspirin.

Event rates
The early and late adverse event rates are noted in Table 2. Although there were 49 deaths in this series (4 early, 45 late), only 10 were valve related and 11 cardiac related, Twenty-seven patients died from other causes.

Cardiac-related deaths
Cardiac-related deaths were usually due to cardiac arrest from arrhythmia, congestive failure, or coronary artery disease with or without documented myocardial infarction.

Other causes of death
Other causes of death included malignancy, primarily lung (17 patients), cerebral vascular accidents (2 patients), respiratory complications (6 patients), and suicide (2 patients).

Freedom from valve-related complications
Actuarial survivals (Kaplan–Meier) and freedom from valve-related complications are listed in Table 2, and shown in Figures 1, 2, and 3. Actuarial survival at 6 years (freedom from all cause death) was 85.5%, and freedom from valve-related death (Fig 1), was 96.6% at 6 years. Freedom from structural deterioration overall (Fig 2) was 97.9% at 6 years, but for patients older than 60 years, there was 100% freedom from structural deterioration.

View larger version (21K): [in this window] [in a new window]   Fig 1. Freedom from valve-related death (Kaplan–Meier) in 447 patients followed-up for as long as 96 months.

View larger version (20K): [in this window] [in a new window]   Fig 2. Freedom from structural deterioration (Kaplan–Meier).

View larger version (19K): [in this window] [in a new window]   Fig 3. Freedom from structural deterioration in 323 patients older than 60 years followed-up for as long as 96 months showing 100% functional integrity.

	Comment

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
The TSPV is sized to the sinotubular junction, which is usually one to two sizes larger than the measured annulus in patients with aortic valve pathology. This sizing provides for a large leaflet coaptation surface and allows for some expansion of the debrided annulus [7]. There is thus a preponderance of "oversized" valves in this series, although it is recognized that the internal diameters are 4 mm less than the external, which corresponds to the manufacturer’s labeled size [8]. The resulting superb early hemodynamics of the TSPV appear to be well maintained over time with improved left ventricular mass regression and only a modest increase in the degree of AI. This finding is reflected in patient well-being, with 83.7% of patients categorized as NYHA I and 14.0% as NYHA II at 7 years. The stable functional integrity of the valve may be a result of its incorporation within the aortic root in a subcoronary position similar to that of an allograft. This positioning allows full excursion of the leaflets during systole and permits the aortic sinuses to participate in diastolic pressures during valve closure. Removal of a rigid stent allows normal aortic cusp motion and preserves the dynamic nature of the aortic root complex [9, 10]. This stable functional state is reflected in 98.4% freedom from explant at 72 months (and 91.7% at 84 months) with 97.9% freedom from structural deterioration at 72 months (93.8% at 84 months) and 100% for patients more than 60 years. Of the four explants because of structural deterioration at 5.8, 5.9, 6.8, and 7.0 years postoperatively, all were the result of late development of severe AI due to tears in a cusp, or a commissure. No significant valve or leaflet calcification was noted.

In one instance, the insufficiency developed after lifting weights up to 300 lbs, in another the right cusp was torn due to gross dilatation of the right aortic sinus, suggesting that excess aortic pressure or root distortion were causative factors. It is noteworthy that all these explants (including the patients with late AI because of aortic dilatation) were for patients in their sixth postoperative year, all relatively young (between 36 and 43 years of age), and all had congenital bicuspid valves. The inference that these patients may not be candidates for stentless valve insertion, perhaps due to the known aortopathy associated with bicuspid valves, requires further consideration.

The early and late adverse event rates were acceptably low. The linearized rate for all embolism was 1.0%/patient-year, structural deterioration 0.2%/patient-year, and endocarditis 0.4%/patient-year. No instances were noted of major paravalvular leaks, clinically significant hemolytic anemia, or valve thrombosis. Only 5 patients underwent reoperation for AI, a linearized rate of 0.3%/patient-year. There was a distinct increase in the incidence of trivial (1+) and mild (2+) AI, whereas the incidence of no AI (0+) decreased from 89% early to 68% postoperatively. This finding may have been due to subtle expansion of the aorta, although this assumption was unproved. Most late deaths were due to cancer or cardiac or respiratory complications.

Similar excellent clinical outcomes have been noted for other stentless aortic valves and therefore must reflect the superb hemodynamic characteristics, the lack of anticoagulants, an endothelial surface with central flow, and maintenance of the functional integrity of the dynamic aortic root components [6]. Nonetheless, unexplained and unexpected cusp tears have occurred, as has progressive aortic dilatation.

Progressive aortic dilatation has been addressed by fixation of the sinotubular ring by either a measured Dacron band, frequent "tucks," or complete transection of the aorta with a double layer closure (T.E. David: Fixation of the sinotubular junction after aortic valve replacement with the Toronto SPV valve. St. Jude Medical communication, 2000). The total freedom from structural deterioration in patients older than 60 years emphasizes the value of bioprosthetic implants for the elderly population. Little or no calcification was noted in the cusps or supporting porcine aortic tissue in explants. Whether the valve will continue to perform without deterioration over the next few years is speculative.

These results suggest that patients requiring aortic valve replacement, especially those older than 60 years, may have stentless valve implants with a low rate of postoperative clinical complications and 96.3% freedom from valve-related death at almost 9 years; the late deaths, attributed to coronary and vascular disease, cancer, and respiratory insufficiency, represent initial comorbidities of the patient population. The stable, functional well-being and excellent NYHA functional class without fear of valve thrombosis, embolism or deterioration, and without concern of major bleeding from anticoagulants, make the TSPV an attractive alternative for patients requiring aortic valve replacement.

	Acknowledgments

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
Bernard S. Goldman’s research interests are supported by the Milton and Ethel Harris Family Cardiovascular Research Fund and the Irving and Dorothy Shoichet Cardiovascular Fund, at the University of Toronto.

	Footnotes

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 
The authors are members of the Medical Advisory Board for the Stentless Porcine Valve of St. Jude Medical Inc, St. Paul, MN, and receive an honorarium for attendance at Board Meetings.

The data included in this study have been generated by St. Jude Medical Inc, from clinical information provided by the authors and their individual Study Coordinators. The follow-up activities are funded by St. Jude Medical for obtaining clinical information and echocardiographic data.

	Appendix

 
Investigational device exemption sites

Sunnybrook & Women’s College Health Sciences Centre, Toronto, Canada 89 Toronto General Hospital, Toronto, Canada 174 Queen Elizabeth II Health Sciences Centre, Halifax, Canada 39 Lankenau Hospital, Philadelphia, PA 33 University of Washington Medical Centre, Seattle, WA 57 St. Thomas Hospital, Nashville, TN 55 Total All Hospitals 447

	References

Top Footnotes Abstract Introduction Material and methods Results Comment Acknowledgments References

 

1. Del Rizzo D., Goldman B.S., Christakis G.T., et al. Haemodynamic benefits of the Toronto stentless valve. J Thorac Cardiovasc Surg 1996;112:1431-1438.[Abstract/Free Full Text]
2. Jin X.Y., Gibson D.G., Yacoub M., et al. Perioperative assessment of aortic homograft, Toronto stentless valve, and stented bioprosthesis in the aortic position. Ann Thorac Surg 1995;60:S395-S401.
3. Goldman B.S., Christakis G.T., David T.E., et al. Will stentless valves be durable? The Toronto valve (TSPV) at 5 to 6 years. Semin Thorac Cardiovasc Surg 1999;11:42-49.[Medline]
4. David T.E., Feindel C., Scully H.E., et al. Aortic valve replacement with stentless porcine aortic valves: a ten-year experience. J Heart Valve Dis 1998;7:250-254.[Medline]
5. Silberman S., Shaheen S., Fink D., et al. Comparison of exercise hemodynamics between non-stented aortic bioprostheses, mechanical valves, and normal native aortic valves. J Card Surg 1998;13:412-416.[Medline]
6. Westaby S., Huysmans H., David T.E. Stentless aortic bioprostheses. Compelling data from the Second International Symposium. Ann Thorac Surg 1990;65:235-240.[Abstract/Free Full Text]
7. Nagy Z.L., Fisher J., Walker P.G., Walterson K.G. The effect of sizing on the in vitro hydrodynamic characteristics and leaflet motion of the Toronto SPV stentless valve. J Thorac Cardiovasc Surg 1999;117:92-98.[Abstract/Free Full Text]
8. Christakis G.T., Buth K.J., Goldman B.S., et al. Inaccurate and misleading valve sizing: a proposed standard for valve size nomenclature. Ann Thorac Surg 1998;66:1198-1203.[Abstract/Free Full Text]
9. David T.E. Aortic valve replacement with stentless porcine bioprostheses. J Card Surg 1998;13:344-351.[Medline]
10. Westaby S., Horton M., Jin X.Y., et al. Survival advantage of stentless aortic bioprostheses. Ann Thorac Surg 2000;70:785-791.[Abstract/Free Full Text]

This article has been cited by other articles:

				S. Yadav, A. J. Hodge, A. D. Hilless, and P. D. Skillington Outcomes with Toronto stentless porcine aortic valve: the Australian experience Interactive CardioVascular and Thoracic Surgery, December 1, 2006; 5(6): 709 - 715. [Abstract] [Full Text] [PDF]

				N. D. Desai, O. Merin, G. N. Cohen, J. Herman, S. Mobilos, J. Y. Sever, S. E. Fremes, B. S. Goldman, and G. T. Christakis Long-Term Results of Aortic Valve Replacement With the St. Jude Toronto Stentless Porcine Valve Ann. Thorac. Surg., December 1, 2004; 78(6): 2076 - 2083. [Abstract] [Full Text] [PDF]

				D. B. Doty and J. R. Doty Stentless Aortic Valve Replacement: Bioprostheses Card. Surg. Adult, January 1, 2003; 2(2003): 889 - 898. [Full Text]

				A. R. Akar, A. Szafranek, C. Alexiou, R. Janas, M. J. Jasinski, J. Swanevelder, and A. W. Sosnowski Use of stentless xenografts in the aortic position: determinants of early and late outcome Ann. Thorac. Surg., November 1, 2002; 74(5): 1450 - 1457. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Goldman, B. S. Articles by Petracek, M. R. Search for Related Content PubMed PubMed Citation Articles by Goldman, B. S. Articles by Petracek, M. R. Related Collections Valve disease