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J Thorac Cardiovasc Surg 1994;108:1030-1036
© 1994 Mosby, Inc.

SURGERY FOR ACQUIRED HEART DISEASE

Aortic valve replacement with a stentless porcine aortic valveA six-year experience

Toronto, Ontario, Canada

From the Divisions of Cardiovascular Surgery and Cardiology of The Toronto Hospital and the University of Toronto, Toronto, Ontario, Canada.

Address for reprints: Tirone E. David, MD, 200 Elizabeth St.— 13EN219, Toronto, Ontario M5G 2C4, Canada.

Abstract

A stentless porcine aortic valve was used for aortic valve replacement in 123 patients from 1987 to 1993. The mean age of 86 men and 37 women was 61 ± 12 years. Most patients had aortic stenosis; one-third had coronary artery disease and six had mitral valve disease. The stentless valve was secured in the subcoronary position by the same technique used for a freehand aortic valve homograft. The size of valve was based largely on the diameter of the sinotubular junction of the aortic root. The mean valve size was 26.5 mm (range 19 to 29 mm) and 87% were 25 mm or larger. Two operative deaths occurred, one the result of myocardial infarction and the other the result of infective endocarditis. Patients have been followed up from 3 to 77 months, mean 22 months. Three late deaths, none related to the valve, have occurred. The actuarial survival at 6 years was 91% ± 4%. Four transient cerebral ischemic events have occurred, but two patients had extracranial cerebrovascular disease. One patient had endocarditis late in the postoperative period and required reoperation. All patients had Doppler echocardiographic studies before discharge from the hospital, 3 to 6 months later and annually. Only 15 patients have aortic insufficiency, trivial in 6 and mild in 9. The peak and mean systolic gradients decreased significantly during the first 3 to 6 months after implantation (p < 0.001), and the effective valve areas increased significantly during this time interval (p < 0.001). This improvement in valve hemodynamics is believed to be due to remodeling of the aortic root and regression of left ventricular hypertrophy. The results of aortic valve replacement with this stentless bioprosthesis have been excellent and justify its continued use in older patients. (J THORAC CARDIOVASC SURG 1994;108:1030-6)

Aortic valve replacement (AVR) with a stentless biologic valve was first reported by Ross ¹ in 1962 and Barratt-Boyes ² in 1964. These surgeons implanted an aortic valve homograft in the subcoronary position using a technique described by Duran and Gunning. ³ Binet and associates ⁴ described five patients who had AVR with stentless heterologous aortic valves in 1965. O'Brien and colleagues ⁵ accumulated a formidable experience with formaldehyde-preserved porcine stentless valves. With the development of tissue fixation with glutaraldehyde ⁶ and with the availability of commercially stented porcine valves, the interest in stentless porcine valves vanished.

In an attempt to improve the hemodynamic features and durability of heterologous tissue valves, we ^7,8 began a clinical trial on AVR with a stentless porcine aortic valve in 1987. Since then interest in stentless porcine aortic bioprostheses has been renewed, and all major heart valve manufacturers now have their version of the stentless porcine aortic valve available for clinical investigation in the United States and in other countries. Herewith we report our experience with the stentless porcine aortic valve that we originally described. ^7,8 This valve is now made by St. Jude Medical, Inc. (St. Paul, Minn.) and its trademark is the Toronto SPV bioprosthesis.

PATIENTS AND METHODS

From October 1987 to December 1993, 123 patients underwent AVR with a stentless porcine aortic valve. Table I shows the preoperative clinical data of these patients. Left ventricular ejection fraction was estimated by echocardiography or contrast ventriculography. Table II shows the operative data. The stentless porcine aortic valve was secured in the patient's aortic root with two layers of sutures, similar to what is done during AVR with a freehand sewn aortic valve homograft. The selection of the size of the stentless porcine aortic valve was based on the diameter of the aortic anulus in the first 29 patients, and it was based largely on the diameter of the sinotubular junction in the remaining 94. In 11 patients it was necessary to reduce the diameter of the sinotubular junction because it exceeded the diameter of the aortic anulus.

Statistical analyses were performed with BMDP software (BMDP Statistical Software, Los Angeles, Calif.). Actuarial survival and freedom from complications were calculated by the life table method. Results were expressed in percentages of the means and the percentages of the standard errors of the means. Echocardiographic parameters were expressed as the means and standard deviation of the means. The temporal changes in these parameters were compared by Student's t tests.

RESULTS

Operative mortality and morbidity
Two operative deaths occurred. One patient with isolated AVR had a cardiac arrest soon after the operation and could not be resuscitated. Autopsy showed papillary muscles necrosis. The second patient had an uneventful AVR and was discharged from the hospital 1 week after the operation. She was readmitted during the fourth postoperative week with the diagnosis of acute infective endocarditis caused by Staphylococcus aureus. At reoperation, an extensive aortic root abscess involving the tricuspid valve was found. She died 2 days after reoperation.

Eleven patients had one or more postoperative complications. Two patients had perioperative myocardial infarction. Four patients had low output syndrome for which they were treated with intraaortic balloon pumping; ischemia of the leg developed in one of them and resulted in permanent foot drop. One patient had a stroke after spontaneous cardioversion of atrial fibrillation but recovered completely. Two patients had respiratory failure necessitating prolonged assisted ventilation. And three patients had fever and positive blood cultures (Staphylococcus aureus, Enterococcus faecalis, and Listeria monocytogenes) without clinical or echocardiographic evidence of endocarditis and were treated with intravenous antibiotics for 6 weeks.

Late mortality
Patients have been observed from 3 to 75 months, mean 22 months. Three late deaths have occurred, all in patients older than 75 years of age: A 79-year-old man died of skin cancer 9 months after AVR and repeat coronary artery bypass; an 81-year-old man died of ventricular arrhythmias and heart failure 17 months after AVR and mitral valve repair with poor left ventricular function; and a 77-year-old woman died of myocardial infarction 32 months after AVR and triple coronary artery bypass. The stentless porcine aortic valve was functioning normally in these three patients.

Fig. 1 shows the acturial survival; at 6 years 91% ± 4% of the patients were alive.

View larger version (12K): [in this window] [in a new window]   Fig. 1. Actuarial survival after AVR with the stentless pocine aortic valve.

Infective endocarditis
One patient had infective endocarditis because of Streptococcus viridans 53 months after the operation. He was reoperated on at another hospital; the operative report indicated that the infection resembled that on a native aortic valve, that it was limited to the leaflets of the stentless porcine aortic valve, and that no difficulty was encountered in explanting the valve. This patient recovered uneventfully.

Reoperation
The only patient who had required repeat AVR was the one with infective endocarditis just described. However, two other patients have required further cardiac operations. A 55-year-old woman needed mitral valve replacement for mitral stenosis 22 months after AVR. The stentless porcine aortic valve was functioning normally and was left in place, but consent was obtained to inspect and photograph it (Fig. 2). A 26-year-old man underwent heart transplantation for end-stage dilated cardiomyopathy 32 months after AVR. The stentless porcine aortic valve had a minimal peak systolic gradient and mild aortic insufficiency by Doppler echocardiography. The pathologic examination of the explanted valve disclosed mild calcification of a leaflet close to a commissural area, which caused abrasion of the opposing leaflet (Fig. 3).

View larger version (162K): [in this window] [in a new window]   Fig. 2. Intraoperative photograph of a stentless porcine aortic valve 22 months after implantation.

View larger version (141K): [in this window] [in a new window]   Fig. 3. Photograph of a stentless porcine aortic valve 32 months after implantation in a 26-year-old patient who required heart transplantation.

Hemodynamic assessment by Doppler echocardiography
Among the first 29 patients who had AVR with a stentless porcine aortic valve, aortic insufficiency was detected in 7 of 28 survivors (25%). It was graded trivial in 3 patients and mild in 4. In these 29 patients the selection of the size of the stentless porcine aortic valve was based solely on the diameter of the aortic anulus. In the last 94 patients aortic insufficiency was detected in only 8 of 93 survivors (8.6%). It was graded trivial in 3 and mild in 5. In these 94 patients the diameter of the sinotubular junction was taken into consideration when the size of the stentless porcine aortic valve was selected.

Table III shows the effective valve areas as well as the mean and peak systolic gradients obtained by Doppler echocardiography soon after the operation, 3 to 6 months later, and 11 to 14 months later in patients with valves of 23 mm and larger. The effective valve areas increased significantly during the first 3 to 6 months after implantation (p < 0.001). In addition, the mean and peak systolic gradients across the stentless porcine aortic valve decreased significantly during the first 3 to 6 months after implantation (p < 0.001).

One of the most gratifying features of the Toronto SPV bioprosthesis has been its hemodynamic performance. As shown in Table III, the resistance to flow across the stentless porcine aortic valve decreases during the first 3 to 6 months after implantation. These findings are probably explained by remodeling of the aortic root after implantation of the stentless porcine aortic valve and by rapid regression of left ventricular hypertrophy in patients with aortic stenosis. The aortic root is traumatized during implantation of a stentless porcine aortic valve with consequent inflammatory reaction. The edema and induration may limit the opening of the leaflets. As the valve heals in the aortic root, its leaflets open more freely. Sequential Doppler echocardiographic studies showed that the flow across the left ventricular outflow tract becomes laminar after 3 to 6 months in almost all patients who had AVR with the Toronto SPV bioprosthesis. With the exception of aortic valve homografts and pulmonary valve autografts, we have not seen other tissue or mechanical valves with such hemodynamic features.

Aortic insufficiency after implantation of stentless biological valves is common. ^8-10 Although the aortic insufficiency is usually mild, it may however predispose the valve to premature failure because of either increased mechanical stress or infective endocarditis. When we first started implanting the stentless porcine aortic valve we used the diameter of the aortic anulus to select the size of the valve as we did during AVR with aortic valve homografts. This approach works so long as the patient's aortic root is normal. However, most patients with aortic valve disease have an abnormal aortic root, and implantation of a normal aortic valve in an abnormal aortic root will result in aortic insufficiency. Therefore, other factors must be considered during AVR with a stentless biologic valve such as the Toronto SPV bioprosthesis. In human beings with a normal aortic root the diameter of the aortic anulus is approximately 10% to 15% larger than the diameter of the sinotubular junction. ^11,12 In pigs the relationship between these two diameters is similar to that in human beings. ^12-14 Because the spatial relationships of the three commissures of the aortic valve are crucial for proper leaflet coaptation, the diameter of the sinotubular junction is more important than the diameter of the aortic anulus for aortic valve competence after implantation of a stentless porcine aortic valve. Therefore, we use the diameter of the sinotubular junction to select the size of the Toronto SPV bioprosthesis. If the aortic anulus is one size smaller than the sinotubular junction, a Toronto SPV bioprosthesis of same diameter as the sinotubular junction can be easily implanted. Greater discrepancies between these two diameters require tailoring of the sinotubular junction after implantation of the Toronto SPV bioprosthesis. We have accomplished that by simply plicating the sinotubular junction at the level of the commissures of the stentless porcine aortic valve. This is done with one or two pledget-supported sutures. We have reduced the diameter of the sinotubular junction to the diameter of the stentless porcine aortic valve.

Another anatomic feature that may influence the hemodynamics of the Toronto SPV bioprosthesis is its orientation within the aortic root of the patient. In human beings, the noncoronary cusp and its sinus is frequently larger than the right and left cusps and sinuses. ^12-14 In pigs, the right cusp is usually the largest of the three. ¹² The right cusp of a porcine aortic valve is the one attached to the muscular septum and is easily recognizable. During implantation of the Toronto SPV bioprosthesis we orient the cusp attached to the muscle shelf toward the noncoronary aortic sinus of the patient. Because the noncoronary aortic sinus is frequently enlarged and sagging on the roof of the left atrium in patients with long-standing aortic valve disease, suturing the inflow of the stentless porcine aortic valve in a supraannular position along the noncoronary sinus allows for implantation of a larger valve than the diameter of the aortic anulus, and it also corrects the unevenness of the level of the aortic anulus among the three aortic sinuses.

Another gratifying feature of the Toronto SPV bioprosthesis has been its low rate of valve-related complications and relatively high actuarial survival of the patients. In a similar patient population who had AVR with the Hancock II bioprosthesis (Johnson & Johnson Cardiovascular, King of Prussia, Pa.) in our institution, the actuarial survival at 6 years was 81% ± 2%. ¹⁵ Because these two groups of patients may not have been comparable, we developed a case-matched study using age ±5 years, aortic valve lesion, New York Heart Association functional class, left ventricular ejection fraction ±10%, and coronary artery disease. One hundred one patients were matched from each group and the actuarial survival at 5 years was 93% ± 4% for the patients with the Toronto stentless porcine valve bioprosthesis and 86% ± 5% for those with the Hancock II bioprosthesis. This difference did not reach statistical significance, but proportional hazard analysis revealed that valve-related complications were twice as common among patients with stented porcine valves as in those with stentless valves during the same follow-up interval. If this trend continues, AVR with stentless porcine valves will result in statistically better long-term survival than AVR with stented porcine valves.

In experimental animals stentless porcine aortic valves are less likely to calcify than are stented ones. ¹⁶ Although our experience is anecdotal, an explanted stentless porcine aortic valve from a 26-year-old patient revealed signs of early calcification (see Fig. 3). Since 1991, we have implanted this valve only in older patients. The Toronto SPV bioprosthesis is being implanted in Canada and in the United States under an Investigation Device Exemption (IDE) and it cannot be used in patients younger than 35 years of age.

The issue of durability of stentless porcine aortic valves remains unresolved. ^8,17 Further follow-up will be required to determine whether they are more durable than stented porcine valves. The experience with aortic valve homografts suggests that the durability of this valve is shortened when it is mounted in a stent before implantation. ¹⁸ By extrapolation, one would expect the stentless porcine aortic valve to be more durable than the stented porcine valve.

We are indebted to Dr. A. Kerwin and Ms. J. David for their assistance in the preparation of this manuscript.

Appendix: APPENDIX

The following formulas were used for calculation of gradients and valve areas by Doppler echocardiography.

Peak systolic gradient (mm Hg) = 4 (Va² - Vo²)

where Va is the peak velocity in the aortic valve and Vo is the peak velocity in the left ventricular outflow.

Mean systolic gradient (mm Hg) = 4 ([0.65Va]² - [0.65Vo]²)

where Va is the peak velocity in the aortic valve and Vo is the peak velocity in the left ventricular outflow.

where V₁ is the mean velocity in the left ventricular outflow, V₂ is the mean velocity in the aortic valve and A_LVOF is the area of the left ventricular outflow tract.

Footnotes

Read at the Seventy-fourth Annual Meeting of The American Association for Thoracic Surgery, New York, N.Y., April 25-28, 1994.

References

1. Ross DN. Homograft replacement of the aortic valve. Lancet 1962;2:487.[Medline]
   
2. Barratt-Boyes BG. Homograft aortic valve replacement in aortic valve incompetence and stenosis. Thorax 1964;19:131-50.
   
3. Duran CG, Gunning AJ. A method for placing a total homologous aortic valve in the subcoronary position. Lancet 1962;2:488.[Medline]
   
4. Binet JP, Duran CG, Carpentier A, Langlois J. Heterologous aortic valve transplantation. Lancet 1965;2:1275.[Medline]
   
5. O'Brien MF, Neilson GH, Galea EG, et al. Heterograft valves: an analysis of clinical results of valve replacement. Circulation 1970;16,17(Suppl):II16-9.
   
6. Carpentier A, Lemaigre G, Robert L, et al. Biological factors affecting long-term results of valvular heterografts. J THORAC CARDIOVASC SURG 1969;58:467-83.[Medline]
   
7. David TE, Ropchan GC, Butany JW. Aortic valve replacement with stentless porcine bioprostheses. J Cardiac Surg 1988;3:501-5.[Medline]
   
8. David TE, Pollick C, Bos J. Aortic valve replacement with stentless porcine aortic bioprosthesis. J THORAC CARDIOVASC SURG 1990;99:113-8.[Abstract]
   
9. Casabona R, De Paulis R, Zattera GF, et al. Stentless porcine and pericardial valve in aortic position. Ann Thorac Surg 1992;54:681-5.[Abstract]
   
10. Kirklin JK, Smith D, Novick W, et al. Long-term function of cryopreserved aortic homografts: a ten-year study. J THORAC CARDIOVASC SURG 1993;106:154-66.[Abstract]
    
11. Kunzelman KS, Grande KJ, David TE, Cochran RP, Verrier ED. Aortic root and valve relationship: impact on surgical repair. J THORAC CARDIOVASC SURG 1994;107:162-70.[Abstract/Free Full Text]
    
12. Grande KJ, Kunzelman KS, Cochran RP, David TE, Verrier ED. Porcine aortic leaflet arrangement may contribute to clinical xenograft failure. ASAIO J 1993;39:918-22.[Medline]
    
13. Sands MP, Rittenhouse EA, Mohri H, Merendino KA. An anatomical comparison of human, pig, calf and sheep aortic valves. Ann Thorac Surg 1969;8:407-14.[Medline]
    
14. Silver MA, Roberts WC. Detailed anatomy of the normally functioning aortic valve in hearts of normal and increased weight. Am J Cardiol 1985;55:454-61.[Medline]
    
15. David TE, Armstrong S, Zhao S. Clinical and hemodynamic assessment of the Hancock II bioprosthesis. Ann Thorac Surg 1992;54:661-8.[Abstract]
    
16. Hazekamp MG, Goffin YA, Huysmans HA. The value of the stentless biovalve prosthesis: an experimental study. Eur J Cardiothorac Surg 1993;7:514-9.[Abstract]
    
17. Hofig M, Nellessen U, Mahmoodi M, et al. Performance of a stentless xenograft aortic bioprosthesis up to four years after implantation. J THORAC CARDIOVASC SURG 1992;103:1068-73.[Abstract]
    
18. Angell WW, Oury JH, Lamberti JJ, Koziol J. Durability of the viable aortic allograft. J THORAC CARDIOVASC SURG 1989;98:48-56.[Abstract]
    

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This Article Abstract 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 Author home page(s): Tirone E. David Christopher M. Feindel Hugh E. Scully Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by David, T. E. Articles by Rakowski, H. Search for Related Content PubMed PubMed Citation Articles by David, T. E. Articles by Rakowski, H.