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Clinical experience with stentless pericardial aortic monopatch for aortic valve replacement
J THORAC CARDIOVASC SURG 1987;93:19-26
Clinical experience with stentless pericardial aortic monopatch for aortic valve replacement A stentless pericardial aortic monopatch was used in 60 consecutive patients undergoing aortic valve replacement The monopatch is constructed of a sheet of glutaraldehyde-treated bovine pericardium, tailored and shaped to fit the aortic anolus, and is sutured in place without a stent or sewing ring. The valve area is effectively preserved by this method. Results indicate that this technique is simple, inexpemive,and applicable to all cases of aortic valvedisease. It does not require anticoagulation and may allow for annular growth when used in children. This technique is particularly suitable for patients with infective endocarditis because the amount of foreign material is minimized.
Randas J. Vilela Batista, M.D. (by invitation), Alexander Dobrianskij, M.D. (by invitation), Marino Comazzi, Jr., M.D. (by invitation), Luiz T. Lessa Neto, M.D. (by invitation), Gilberto Rocha, M.D. (by invitation), Fernando Sartori, M.D. (by invitation), Ricardo Westphal, M.D. (by invitation), Jorge R. Timi, M.D. (by invitation), Ricardo Moreira, M.D. (by invitation), and Paulo F. Oliveira, M.D. (by invitation), Curitibia, Brazil Sponsored by Tomas A. Salerno, M.D., Toronto, Ontario, Canada
h e cost and complication rates for aortic valve replacement (A VR) with a mechanical prosthesis in our environment led us to use a glutaraldehyde-treated bovine pericardium without a stent or sewing ring for AVR. The present study is the review of our clinical experience with this method of A VR.
Table I. Distribution of aortic valve lesions and
associated cardiac lesions in 60 patients undergoing AVR with the stentless monopatch Lesions Aortic valve lesions Aortic regurgitation Aortic stenosis Mixed lesions Associated lesions Mitral valve Mitral and tricuspid valve Ascending aortic aneurysm CAD CAD + LV aneurysm Infective endocarditis Total
Materials and patients From August 1983 to April 1986, the aortic valve of
60 consecutive patients was replaced with a stentless pericardial aortic monopatch. There were 40 male and 20 female patients aged 15 to 74 (mean 36 years). The indications for operation are shown in Table I. Preoperative cardiac catheterization was performed in all patients with the exception of three who were in severe pulmonary edema because of bacterial endocarditis. Twenty-nine patients were in New York Heart Association Class IV, 30 in Class III, and one patient in Class II preoperatively. From the Hospital Nossa Senhora das Gracas, Curitiba, Brazil. Read at the Sixty-sixth Annual Meeting of The American Association for Thoracic Surgery, New York, N. Y., April 28-30, 1986. Address for reprints: Dr. R. J. V. Batista, Hospital Nossa Senhora das Gracas, Rua Alcides Munhoz 433, Merces, Curitiba, PR, Brazil.
Legend:
No.
32 (53%) 10 (16%) 18 (30%)
17 3
3 2 I 4 30 (50%)
CAD, Coronary artery disease. LV, Left ventricular.
Operative techniques. Bovine pericardium, obtained from 2-year-old calves, was treated with 0.6% glutaraldehyde for 7 days and preserved in 20% formaldehyde. Cardiopulmonary bypass with systemic hypothermia to 28 0 C was used in all patients. Cardioplegic arrest was achieved with a crystalloid solution (l L of 5% glucose in water, 20 mEq of potassium chloride, sodium bicarbonate to produce a pH of 8, temperature 4 0 C) without left 19
The Journal of
2 0 Vilela Batista et al.
Thoracic and Cardiovascular Surgery
Fig. 1. Configuration of stentless pericardial aortic monopatch after tailoring of patient's native valve leaflets superimposed on the monopatch. Note the excess valve above the native commissure.
Fig. 2. Cadaver model of monopatch after it has been sewn to the anulus. Note that the valve is still inverted into the left ventricle at this stage.
ventricular venting. The aortotomy was made transversely 2 em above the right coronary artery and was extended vertically toward the middle of the noncoronary cusp. After excision of the native aortic valve and decalcification of the anulus, the diameter of the anulus was measured. The necessary length of the pericardial patch was determined by multiplying by three to obtain the approximate circumference (C = D X 11"); then 1 to 2 cm was added, depending on the shape of the aortic root, to allow for suturing. The width of the patch was approximately one third of the patch length. The patch was then folded lengthwise in thirds and tailored to fit the shape of one cusp. This resulted in a patch consisting of three cusps united by two commissures (Fig. I). The patch was then inverted into the left ventricle, and three running sutures of 4-0 braided material were used to sew it to the anulus, starting at each commissure (Fig. 2). After being sutured, the patch was everted back into the aorta. The width of the patch was greater than the height of the native commissures by I to 1.5 ern, This
maneuver elongated the commissures. However, the leaflet part of the patch was tailored so that the point of coaptation was lower than the new commissure by 0.5 em. Tailoring the leaflet in this manner exaggerated the area of leaflet coaptation to allow for remodeling after insertion and thereby minimized the chance of postoperative aortic regurgitation. The reversed funnel shape of the valve was created by progressively gathering more pericardium as the patch was anchored to the free aortic wall. Once the new commissures were completed, the sutures were exteriorized so that the knots could be tied outside the aorta (Fig. 3). The cross-clamp time for this series of patients ranged from 36 to 80 minutes (mean 45 minutes). Gradients were measured in the immediate post-pump period by fluid-filled catheters with a 19 gauge needle in the left ventricle and ascending aorta. Results Four patients died within 48 hours of operation (6%). Three of them had low output syndrome with severe
Volume 93 Number 1 January 1987
Stentless pericardial aortic monopatch 2 1
Fig. 3. A, Cadaver model after commissures of the monopatch have been sewn to aorta. Note that the sutures have been exteriorized and the knots are outside the aorta. B, Completed monopatch with aorta filled and pressurized. Note competence of the monopatch.
myocardial dysfunction evident shortly after reperfusion. The cause was unclear because they both had a short ischemic period (less than 45 minutes) with adequate myocardial protection. The fourth patient died of a perioperative myocardial infarction associated with coronary artery revascularization. Autopsies were performed in all four patients and the valves and bypass grafts appeared normal. Two late deaths occurred (4%). One patient, with phlegmasia cerulea dolens, died of a pulmonary embolus 40 days postoperatively. The other patient had a history of severe peripheral and cerebrovascular disease and underwent coronary bypass grafting and left ventricular aneurysmectomy; he died of a recurrent cerebral vascular accident 45 days postoperatively. The actuarial survival curve is shown in Fig. 4.
Table II. Morbidity associated with AVR with the stentless monopatch No. A-V block Dissection of ascending aorta Sternal dehiscence Stroke with normal CT scan
2 I I I
Legend: A-V. Atrioventricular. CT, Computed tomographic.
Postoperative complications are listed in Table II. One patient required reoperation 18 months later for repair of dissection of the ascending aorta. Another patient had a stroke postoperatively; results of computed tomo-
The Journal of Thoracic and Cardiovascular
2 2 Vilela Batista et al.
Surgery
100 900i~
•
90 ~
80 70
»:
10{60
56
1 12
47
lS
)(1
1 2
::i
2
Yr\
Fig. 4. Actuarial survival curve for patients undergoing AVR with the stentless monopatch.
I
48 '85'%'
7 26
29
1
III
Fig. 5. New York Heart Association classification of all surviving patients before and after AVR with the stentless monopatch.
graphic scanning were normal in this patient and he recovered within a week. Functional improvement was observed in all patients (Fig. 5). All patients were treated with aspirin, 500 mg daily, for the first 6 months without other forms of anticoagulation. No major thromboembolic phenomena were noted in any patient and there were no valve thromboses. Pressure gradients across the aortic valve were sought in the first 20 patients and no gradient was observed. Four patients were recatheterized 18 months after operation and no pressure gradients were observed. A diastolic murmur developed postoperatively in two patients: One had an
associated aortic dissection. The other, a soccer player, was noted to have the murmur during severe exertion and was reoperated on by another surgeon, who found a well-preserved stentless pericardial aortic monopatch. Four patients had AVR with the stentless pericardial aortic monopatch despite active infective endocarditis and severe congestive failure. All recovered without recurrence of infection or valvular regurgitation. One patient, aged 15 years, was admitted with pulmonary edema and severe aortic insufficiency and underwent AVR with the monopatch. On follow-up 2 years later he had grown from a body surface area of 1.3
Volume 93 Number 1
January 1987
Stentless pericardial aortic monopatch
23
Fig. 6. A. Echocardiograms before and 2 years afteroperation showing change in leftventricular dimensions (7.8 cmto 4.8 em). B. Echocardiograms before and 2 years afteroperation showing change in leftatrium (4.8 em to 2.5 em) and aortic annular growth.
to 2.0 m', Echocardiography showed that the left ventricular sizehad decreased from 7.8 em preoperatively to 4.8 em postoperatively and the left atrial size from 4.8 to 2.5 em. In contrast, the aortic root had grown 0.2 em during that period (Fig. 6). Cardiac angiography revealed a markedly improved ejection fraction and a competent aortic valve(Fig. 7). The stentlesspericardial aortic monopatch was made redundant to allow for possible growth. This patient had a systolic murmur immediately postoperatively, which gradually disappeared. Discussion
Both mechanicaland biological valves have been used clinically for the treatment of aortic valve disease.
Long-term results have been excellent with currently available stented pericardial valves, such as the IonescuShiley valve, I without anticoagulation. Unstented tissue valves, such as the autologous pulmonary valve,' the fresh homograft,' and the frozen preserved homograft,' have been promoted because they appear to have better hemodynamic function. Stentlessvalves also have the advantage of having less prosthetic material, which makes them more appealing for the management of patients with infective endocarditis. We have pursued the development of a stentless pericardial valve because it provides a larger effective orifice area than the same valve with a sewing ring. A No. 21 Ionescu-Shiley prosthesis has an effective valve area of 1.38 cm-, Our technique allows for an effective
The Journal of Thoracic and Cardiovascular Surgery
2 4 Vilela Batista et al.
Fig. 7. Angiograms before (top) and 2 years after (bottom) monopatch insertion. Left. Left ventricular injection during diastole. Middle, Left ventricular injection at end-systole. Right, Aortic root injection.
area of greater than 3 cm-, the same as that of a No. 29 prosthesis.' Therefore, this technique obviates the need for an annuloplasty procedure to enlarge the anulus to accommodate a prosthetic valve one to two sizes larger. 6• 7 This is of particular importance in pediatric patients in whom the size of the anulus and gradients across currently available mechanical and biological valves make an annuloplasty procedure mandatory. Because the stentless monopatch is sewn directly to the anulus, there is less chance for coronary ostial obstruction, as may occur with currently available supraannular valves.' Previously described stentless valves have been constructed of autologous fascia lata,9,10 silicone-covered Teflon fabric, I I molded Dacron fabric," and preserved bovine pericardium (Yacoub MH: Personal communication). We have preferred preserved bovine pericardium because of its proven durability I in both stented and unstented valves as well as maintenance of pliability over several years. The stentless pericardial aortic monopatch, may be superior to a single-leaflet configuration (Yacoub MH: Personal communication), because of its preformed commissures. This valve is further strengthened by the lengthening of the commissure height, which increases the area of leaflet coaptation. In pediatric patients there is concern for insertion of a larger prosthesis to accommodate annular growth. This has led us to use a larger stentless monopatch. We have done this in the hope that, if the anulus grows, a larger patch will maintain valvular competence. Four children have undergone this procedure and a 2 year follow-up is
available in one patient (Fig. 6). This child initially had an 18 mm aortic anulus, and a monopatch for a 23 mm valve was inserted. His subsequent growth and clinical improvement (disappearance of systolic murmur and improvement in left ventricular function) have encouraged us to pursue this technique in the pediatric population. Further experience and follow-up are required with this technique in children. Experience with the stentless pericardial aortic monopatch has led us to recommend it as an alternative approach to the management of patients with aortic valve disease. It is particularly applicable for the small aortic anulus, for patients in whom long-term anticoagulation is contraindicated, or in patients with active infective endocarditis. It is conceivable that annul-r growth may occur, which makes the monopatch particularly suitable to pediatric patients. REFERENCES
2
3
4
5
Ionescu MI, Tandon AP, Mary OAS, Abid A: Heart valve replacement with the Ionescu-Shiley pericardial xenograft. J THORAC CARDIOV ASC SURG 73:31-42, 1977 Gula G, Wain WH, Ross ON: Ten years' experience with pulmonary autograft replacements for aortic valve disease. Ann Thorac Surg 28:392-396, 1979 Penta A, Qureshi S, Radley-Smith R, Yacoub MH: Patient status 10 or more years after "fresh" homograft replacement of the aortic valve. Circulation 70: 182-186, 1984 Ross ON, Yacoub MH: Homograft replacement of the aortic valve. A critical review. Prog Cardiovasc Dis 9:275-279, 1969 Morgan RJ, Davis JT, Fraker TO: Current status of valve prosthesis. Surg Clin North Am 65:699-720, 1985
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Stentless pericardial aortic monopatch
January 1987
6 Manouguian S, Seybold-Epting W: Patch enlargement of the aortic valve ring by extending the aortic incision into the anterior mitral leaflet. J THORAC CARDIOVASC SURG 78:402-412, 1979 7 Kono S, Imai Y, Iida Y, Nakajima M, Tatsuno K: A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J THORAC CARDIOVASC SURG 70:909-917, 1975 8 Rothkopf M, Davidson T, Lipscomb K, Narahara K, Hillis LD, Wilkinson JT, Estrera A, Platt M, Mills L: Hemodynamic evaluation of the Carpentier-Edwards bioprosthesis in the aortic position. Am J Cardiol44:209-214, 1979 9 Yates AK: A facial frustrum valve for aortic valve replacement. Thorax 26:184-189, 1971 10 Senning A: Fascia lata replacement of aortic valves. J THORAC CARDIOVASC SURG 54:465-470, 1967 II Hufnagel CA, Conrad PW: The direct approach for the correction of aortic insufficiency. JAMA 178:275-279, 1961 12 Bahnson HT, Spencer FC, Busse EFG, Davis FW: Cusp replacement and coronary artery perfusion in operations on the aortic valve. Ann Surg 152:494-505, 1960
Discussion DR. RADU C. DEAC Tirgu-Mures, Romania
Concerning the terminology, I think the most appropriate term for this type of valvular substitute is "free pericardial aortic graft" rather than "monocusp." The absence of early residual aortic regurgitation in this series is remarkable, because it is very difficult to obtain and maintain a perfectly competent aortic valve with a technique based on measurements at the operating table with the aorta empty. The hemodynamic conditions change after AVR and the dimensions of the aorta change as well. Such a technique is advantageous in a small aortic root and probably causes less mechanical stress without a rigid or flexible support. However, the follow-up is too short to draw any valid conclusions. I would offer a word of caution about the use of bovine pericardium treated with glutaraldehyde in pediatric patients because of calcification complications. Dr. Vilela Batista, have you had any technical failure at the commissural stitches? With a similar technique applied in five patients since 1983, we had one case of endocarditis, and early aortic incompetence occurred in the rest of the patients. DR. SCHLOMO GABBA Y Newark. N. J.
The pericardial xenograft has excellent hemodynamic characteristics and low thrombogenicity, although its long-term durability has not been totally proved. This experience shows that to tailor a valve or to mount a valve, even in manufacturing facilities, is very difficult and requires very strict quality control;yet many of these valves when tested can show failure, prolapse, or unacceptable coaptation features.
25
There are obviously enough pericardial valves already in use, and experience in vitro and in vivoshows that even smaller pericardial valves for the small aortic root still have an acceptable gradient. The gradient is apparently not the problem. A significant gradient can be measured with porcine valves, especially in small sizes, but not with pericardial valves. The real problem with the pericardial valve or any bioprosthesis is the durability. We have compared four types of pericardial valves in our fatigue tester. There was a wide variation in the number of cycles attained until failure, with a wide standard deviation. These are valves that were manufactured by a laboratory with sophisticated quality control. For example, one valve with a mean of 49 million cycles has a mean standard deviation of 20 million cycles. All of the valves show the same pattern. The durability of all valves is unpredictable, even valves that are manufactured in the best conditions. If two pericardial valves of the same type and size are implanted in two patients, there is no way of knowing which one will last longer. Dr. Vilela Batista has described a very elegant way to construct a three-leaflet pericardial valve. I still think it is difficult to manufacture a valve when the aorta is crossclamped, for the reasons that I have described, I do not think this method should be widely used. I see a merit to this method in case a valve is not available. When cost is a major factor, then this method can be a good alternative. I have several questions for Dr. Vilela Batista: How many patients have a diastolic murmur or had reoperation? Were there any children in this series? What was the rate of calcification? DR. ROBERT W. M. FRATER Bronx. N. Y.
The authors have produced an elegant imitation of nature. In particular, their technique takes advantage of the fact that the aortic root is dynamic. John Hunter in the 1760s showed that the aortic valve in diastole is narrower than it is in systole; it widens in systole. He said the diameter increased by one fifth. Stanton Nolan in the 1970s proved this scientifically. That means the difference between a 20 mm and a 24 mm diameter, and it is only a free-form valve of the kind that Dr. Vilela Batista has described that can take advantage of this dynamic aspect of the aortic valve function. I do, however, have misgivings. My colleagues and I have used tanned xenograft pericardium as a free graft within the heart, experimentally and clinically, many times. It certainly heals beautifully. It heals to the papillary muscle, to the aorta, and to the cusp. In young animals it can calcify. In children it thickens. The loss of mobility is not important in many applications, but when xenograft pericardium is used to make a three-cusp valve, it may well be important. As Dr. Carpentier pointed out many years ago, when we mount a biological tissue on a stent, we protect it from the effects of healing; we protect it from the tissues. [Slide] In this lonescu-Shiley valve, explanted after 8 years, one cusp was protected from the effects of tissue ingrowth by
The Journal of
2 6 Vilela Batista et al.
the stent and this cusp stayed pliable. The other two cusps were reached by the tissue growing in over the stent and were rendered immobile, thickened, and essentially useless. It is my fear that what is obviously a tour de force of Dr. Vilela Batista's in implanting these valves will ultimately be defeated by tissue ingrowth. The very fact that makes it possible for him to implant the tanned xenograft pericardium, namely that tissue heals to leather, is also the fact I suspect that will ultimately render it useless. I hate to sound a critical note, but I would ask Dr. Vilela Batista what he foresees for the future of his freehand xenograft aortic valves. DR. VILELA BATISTA (Closing) Dr. Deac, I agree that this valve should not be called stentless, because we use the "aorta" itself as a stent, as nature has done for millions of years. As to your other question, if any of these sutures have pulled out, the answer is, "No." The reason is that we have left these leaflets more redundant for better cusp coaptation. This way, the blood pressure closes the valve side to side and that takes the tension off the suture line. lt is the same principle as that used for flight: What holds an
Thoracic and Cardiovascular Surgery
airplane in the air is not the wings but the air itself. For another example, if someone is climbing up a well wall alone, he will depend a lot on the strength of his own hand grip (suture line). However, if there are two persons climbing up with their backs against each other, they will do it by just walking up, with no need to use their hands. Dr. Gabbay, there must be a misunderstanding here. We never said this valve is "monocuspid." We said that this valveis monopatch and we form three cusps" as suturing goes along. Consequently it is tricuspid. With regard to gradients, I think that a small postoperative gradient with relatively normal left ventricular function and normal cardiac index is not too important. On the other hand, the same small gradient immediately after the operation with very poor left ventricular function and low cardiac index can be a big problem. Dr. Frater, we have not encountered commissure tissue overgrowth so far. However, we cannot say much about it yet, because we have seen only the one patient with a dissected aorta, and those commissures had healed nicely. I guess even if commissure overgrowth eventually happens it will not cause a gradient because the monopatch's effective valve area is much larger than the effective valve areas of stented valves.
Clinical experience with stentless pericardial aortic monopatch for aortic valve replacement A stentless pericardial aortic monopatch was used in 60 consecutive patients undergoing aortic valve replacement The monopatch is constructed of a sheet of glutaraldehyde-treated bovine pericardium, tailored and shaped to fit the aortic anolus, and is sutured in place without a stent or sewing ring. The valve area is effectively preserved by this method. Results indicate that this technique is simple, inexpemive,and applicable to all cases of aortic valvedisease. It does not require anticoagulation and may allow for annular growth when used in children. This technique is particularly suitable for patients with infective endocarditis because the amount of foreign material is minimized.
Randas J. Vilela Batista, M.D. (by invitation), Alexander Dobrianskij, M.D. (by invitation), Marino Comazzi, Jr., M.D. (by invitation), Luiz T. Lessa Neto, M.D. (by invitation), Gilberto Rocha, M.D. (by invitation), Fernando Sartori, M.D. (by invitation), Ricardo Westphal, M.D. (by invitation), Jorge R. Timi, M.D. (by invitation), Ricardo Moreira, M.D. (by invitation), and Paulo F. Oliveira, M.D. (by invitation), Curitibia, Brazil Sponsored by Tomas A. Salerno, M.D., Toronto, Ontario, Canada
h e cost and complication rates for aortic valve replacement (A VR) with a mechanical prosthesis in our environment led us to use a glutaraldehyde-treated bovine pericardium without a stent or sewing ring for AVR. The present study is the review of our clinical experience with this method of A VR.
Table I. Distribution of aortic valve lesions and
associated cardiac lesions in 60 patients undergoing AVR with the stentless monopatch Lesions Aortic valve lesions Aortic regurgitation Aortic stenosis Mixed lesions Associated lesions Mitral valve Mitral and tricuspid valve Ascending aortic aneurysm CAD CAD + LV aneurysm Infective endocarditis Total
Materials and patients From August 1983 to April 1986, the aortic valve of
60 consecutive patients was replaced with a stentless pericardial aortic monopatch. There were 40 male and 20 female patients aged 15 to 74 (mean 36 years). The indications for operation are shown in Table I. Preoperative cardiac catheterization was performed in all patients with the exception of three who were in severe pulmonary edema because of bacterial endocarditis. Twenty-nine patients were in New York Heart Association Class IV, 30 in Class III, and one patient in Class II preoperatively. From the Hospital Nossa Senhora das Gracas, Curitiba, Brazil. Read at the Sixty-sixth Annual Meeting of The American Association for Thoracic Surgery, New York, N. Y., April 28-30, 1986. Address for reprints: Dr. R. J. V. Batista, Hospital Nossa Senhora das Gracas, Rua Alcides Munhoz 433, Merces, Curitiba, PR, Brazil.
Legend:
No.
32 (53%) 10 (16%) 18 (30%)
17 3
3 2 I 4 30 (50%)
CAD, Coronary artery disease. LV, Left ventricular.
Operative techniques. Bovine pericardium, obtained from 2-year-old calves, was treated with 0.6% glutaraldehyde for 7 days and preserved in 20% formaldehyde. Cardiopulmonary bypass with systemic hypothermia to 28 0 C was used in all patients. Cardioplegic arrest was achieved with a crystalloid solution (l L of 5% glucose in water, 20 mEq of potassium chloride, sodium bicarbonate to produce a pH of 8, temperature 4 0 C) without left 19
The Journal of
2 0 Vilela Batista et al.
Thoracic and Cardiovascular Surgery
Fig. 1. Configuration of stentless pericardial aortic monopatch after tailoring of patient's native valve leaflets superimposed on the monopatch. Note the excess valve above the native commissure.
Fig. 2. Cadaver model of monopatch after it has been sewn to the anulus. Note that the valve is still inverted into the left ventricle at this stage.
ventricular venting. The aortotomy was made transversely 2 em above the right coronary artery and was extended vertically toward the middle of the noncoronary cusp. After excision of the native aortic valve and decalcification of the anulus, the diameter of the anulus was measured. The necessary length of the pericardial patch was determined by multiplying by three to obtain the approximate circumference (C = D X 11"); then 1 to 2 cm was added, depending on the shape of the aortic root, to allow for suturing. The width of the patch was approximately one third of the patch length. The patch was then folded lengthwise in thirds and tailored to fit the shape of one cusp. This resulted in a patch consisting of three cusps united by two commissures (Fig. I). The patch was then inverted into the left ventricle, and three running sutures of 4-0 braided material were used to sew it to the anulus, starting at each commissure (Fig. 2). After being sutured, the patch was everted back into the aorta. The width of the patch was greater than the height of the native commissures by I to 1.5 ern, This
maneuver elongated the commissures. However, the leaflet part of the patch was tailored so that the point of coaptation was lower than the new commissure by 0.5 em. Tailoring the leaflet in this manner exaggerated the area of leaflet coaptation to allow for remodeling after insertion and thereby minimized the chance of postoperative aortic regurgitation. The reversed funnel shape of the valve was created by progressively gathering more pericardium as the patch was anchored to the free aortic wall. Once the new commissures were completed, the sutures were exteriorized so that the knots could be tied outside the aorta (Fig. 3). The cross-clamp time for this series of patients ranged from 36 to 80 minutes (mean 45 minutes). Gradients were measured in the immediate post-pump period by fluid-filled catheters with a 19 gauge needle in the left ventricle and ascending aorta. Results Four patients died within 48 hours of operation (6%). Three of them had low output syndrome with severe
Volume 93 Number 1 January 1987
Stentless pericardial aortic monopatch 2 1
Fig. 3. A, Cadaver model after commissures of the monopatch have been sewn to aorta. Note that the sutures have been exteriorized and the knots are outside the aorta. B, Completed monopatch with aorta filled and pressurized. Note competence of the monopatch.
myocardial dysfunction evident shortly after reperfusion. The cause was unclear because they both had a short ischemic period (less than 45 minutes) with adequate myocardial protection. The fourth patient died of a perioperative myocardial infarction associated with coronary artery revascularization. Autopsies were performed in all four patients and the valves and bypass grafts appeared normal. Two late deaths occurred (4%). One patient, with phlegmasia cerulea dolens, died of a pulmonary embolus 40 days postoperatively. The other patient had a history of severe peripheral and cerebrovascular disease and underwent coronary bypass grafting and left ventricular aneurysmectomy; he died of a recurrent cerebral vascular accident 45 days postoperatively. The actuarial survival curve is shown in Fig. 4.
Table II. Morbidity associated with AVR with the stentless monopatch No. A-V block Dissection of ascending aorta Sternal dehiscence Stroke with normal CT scan
2 I I I
Legend: A-V. Atrioventricular. CT, Computed tomographic.
Postoperative complications are listed in Table II. One patient required reoperation 18 months later for repair of dissection of the ascending aorta. Another patient had a stroke postoperatively; results of computed tomo-
The Journal of Thoracic and Cardiovascular
2 2 Vilela Batista et al.
Surgery
100 900i~
•
90 ~
80 70
»:
10{60
56
1 12
47
lS
)(1
1 2
::i
2
Yr\
Fig. 4. Actuarial survival curve for patients undergoing AVR with the stentless monopatch.
I
48 '85'%'
7 26
29
1
III
Fig. 5. New York Heart Association classification of all surviving patients before and after AVR with the stentless monopatch.
graphic scanning were normal in this patient and he recovered within a week. Functional improvement was observed in all patients (Fig. 5). All patients were treated with aspirin, 500 mg daily, for the first 6 months without other forms of anticoagulation. No major thromboembolic phenomena were noted in any patient and there were no valve thromboses. Pressure gradients across the aortic valve were sought in the first 20 patients and no gradient was observed. Four patients were recatheterized 18 months after operation and no pressure gradients were observed. A diastolic murmur developed postoperatively in two patients: One had an
associated aortic dissection. The other, a soccer player, was noted to have the murmur during severe exertion and was reoperated on by another surgeon, who found a well-preserved stentless pericardial aortic monopatch. Four patients had AVR with the stentless pericardial aortic monopatch despite active infective endocarditis and severe congestive failure. All recovered without recurrence of infection or valvular regurgitation. One patient, aged 15 years, was admitted with pulmonary edema and severe aortic insufficiency and underwent AVR with the monopatch. On follow-up 2 years later he had grown from a body surface area of 1.3
Volume 93 Number 1
January 1987
Stentless pericardial aortic monopatch
23
Fig. 6. A. Echocardiograms before and 2 years afteroperation showing change in leftventricular dimensions (7.8 cmto 4.8 em). B. Echocardiograms before and 2 years afteroperation showing change in leftatrium (4.8 em to 2.5 em) and aortic annular growth.
to 2.0 m', Echocardiography showed that the left ventricular sizehad decreased from 7.8 em preoperatively to 4.8 em postoperatively and the left atrial size from 4.8 to 2.5 em. In contrast, the aortic root had grown 0.2 em during that period (Fig. 6). Cardiac angiography revealed a markedly improved ejection fraction and a competent aortic valve(Fig. 7). The stentlesspericardial aortic monopatch was made redundant to allow for possible growth. This patient had a systolic murmur immediately postoperatively, which gradually disappeared. Discussion
Both mechanicaland biological valves have been used clinically for the treatment of aortic valve disease.
Long-term results have been excellent with currently available stented pericardial valves, such as the IonescuShiley valve, I without anticoagulation. Unstented tissue valves, such as the autologous pulmonary valve,' the fresh homograft,' and the frozen preserved homograft,' have been promoted because they appear to have better hemodynamic function. Stentlessvalves also have the advantage of having less prosthetic material, which makes them more appealing for the management of patients with infective endocarditis. We have pursued the development of a stentless pericardial valve because it provides a larger effective orifice area than the same valve with a sewing ring. A No. 21 Ionescu-Shiley prosthesis has an effective valve area of 1.38 cm-, Our technique allows for an effective
The Journal of Thoracic and Cardiovascular Surgery
2 4 Vilela Batista et al.
Fig. 7. Angiograms before (top) and 2 years after (bottom) monopatch insertion. Left. Left ventricular injection during diastole. Middle, Left ventricular injection at end-systole. Right, Aortic root injection.
area of greater than 3 cm-, the same as that of a No. 29 prosthesis.' Therefore, this technique obviates the need for an annuloplasty procedure to enlarge the anulus to accommodate a prosthetic valve one to two sizes larger. 6• 7 This is of particular importance in pediatric patients in whom the size of the anulus and gradients across currently available mechanical and biological valves make an annuloplasty procedure mandatory. Because the stentless monopatch is sewn directly to the anulus, there is less chance for coronary ostial obstruction, as may occur with currently available supraannular valves.' Previously described stentless valves have been constructed of autologous fascia lata,9,10 silicone-covered Teflon fabric, I I molded Dacron fabric," and preserved bovine pericardium (Yacoub MH: Personal communication). We have preferred preserved bovine pericardium because of its proven durability I in both stented and unstented valves as well as maintenance of pliability over several years. The stentless pericardial aortic monopatch, may be superior to a single-leaflet configuration (Yacoub MH: Personal communication), because of its preformed commissures. This valve is further strengthened by the lengthening of the commissure height, which increases the area of leaflet coaptation. In pediatric patients there is concern for insertion of a larger prosthesis to accommodate annular growth. This has led us to use a larger stentless monopatch. We have done this in the hope that, if the anulus grows, a larger patch will maintain valvular competence. Four children have undergone this procedure and a 2 year follow-up is
available in one patient (Fig. 6). This child initially had an 18 mm aortic anulus, and a monopatch for a 23 mm valve was inserted. His subsequent growth and clinical improvement (disappearance of systolic murmur and improvement in left ventricular function) have encouraged us to pursue this technique in the pediatric population. Further experience and follow-up are required with this technique in children. Experience with the stentless pericardial aortic monopatch has led us to recommend it as an alternative approach to the management of patients with aortic valve disease. It is particularly applicable for the small aortic anulus, for patients in whom long-term anticoagulation is contraindicated, or in patients with active infective endocarditis. It is conceivable that annul-r growth may occur, which makes the monopatch particularly suitable to pediatric patients. REFERENCES
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Ionescu MI, Tandon AP, Mary OAS, Abid A: Heart valve replacement with the Ionescu-Shiley pericardial xenograft. J THORAC CARDIOV ASC SURG 73:31-42, 1977 Gula G, Wain WH, Ross ON: Ten years' experience with pulmonary autograft replacements for aortic valve disease. Ann Thorac Surg 28:392-396, 1979 Penta A, Qureshi S, Radley-Smith R, Yacoub MH: Patient status 10 or more years after "fresh" homograft replacement of the aortic valve. Circulation 70: 182-186, 1984 Ross ON, Yacoub MH: Homograft replacement of the aortic valve. A critical review. Prog Cardiovasc Dis 9:275-279, 1969 Morgan RJ, Davis JT, Fraker TO: Current status of valve prosthesis. Surg Clin North Am 65:699-720, 1985
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Stentless pericardial aortic monopatch
January 1987
6 Manouguian S, Seybold-Epting W: Patch enlargement of the aortic valve ring by extending the aortic incision into the anterior mitral leaflet. J THORAC CARDIOVASC SURG 78:402-412, 1979 7 Kono S, Imai Y, Iida Y, Nakajima M, Tatsuno K: A new method for prosthetic valve replacement in congenital aortic stenosis associated with hypoplasia of the aortic valve ring. J THORAC CARDIOVASC SURG 70:909-917, 1975 8 Rothkopf M, Davidson T, Lipscomb K, Narahara K, Hillis LD, Wilkinson JT, Estrera A, Platt M, Mills L: Hemodynamic evaluation of the Carpentier-Edwards bioprosthesis in the aortic position. Am J Cardiol44:209-214, 1979 9 Yates AK: A facial frustrum valve for aortic valve replacement. Thorax 26:184-189, 1971 10 Senning A: Fascia lata replacement of aortic valves. J THORAC CARDIOVASC SURG 54:465-470, 1967 II Hufnagel CA, Conrad PW: The direct approach for the correction of aortic insufficiency. JAMA 178:275-279, 1961 12 Bahnson HT, Spencer FC, Busse EFG, Davis FW: Cusp replacement and coronary artery perfusion in operations on the aortic valve. Ann Surg 152:494-505, 1960
Discussion DR. RADU C. DEAC Tirgu-Mures, Romania
Concerning the terminology, I think the most appropriate term for this type of valvular substitute is "free pericardial aortic graft" rather than "monocusp." The absence of early residual aortic regurgitation in this series is remarkable, because it is very difficult to obtain and maintain a perfectly competent aortic valve with a technique based on measurements at the operating table with the aorta empty. The hemodynamic conditions change after AVR and the dimensions of the aorta change as well. Such a technique is advantageous in a small aortic root and probably causes less mechanical stress without a rigid or flexible support. However, the follow-up is too short to draw any valid conclusions. I would offer a word of caution about the use of bovine pericardium treated with glutaraldehyde in pediatric patients because of calcification complications. Dr. Vilela Batista, have you had any technical failure at the commissural stitches? With a similar technique applied in five patients since 1983, we had one case of endocarditis, and early aortic incompetence occurred in the rest of the patients. DR. SCHLOMO GABBA Y Newark. N. J.
The pericardial xenograft has excellent hemodynamic characteristics and low thrombogenicity, although its long-term durability has not been totally proved. This experience shows that to tailor a valve or to mount a valve, even in manufacturing facilities, is very difficult and requires very strict quality control;yet many of these valves when tested can show failure, prolapse, or unacceptable coaptation features.
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There are obviously enough pericardial valves already in use, and experience in vitro and in vivoshows that even smaller pericardial valves for the small aortic root still have an acceptable gradient. The gradient is apparently not the problem. A significant gradient can be measured with porcine valves, especially in small sizes, but not with pericardial valves. The real problem with the pericardial valve or any bioprosthesis is the durability. We have compared four types of pericardial valves in our fatigue tester. There was a wide variation in the number of cycles attained until failure, with a wide standard deviation. These are valves that were manufactured by a laboratory with sophisticated quality control. For example, one valve with a mean of 49 million cycles has a mean standard deviation of 20 million cycles. All of the valves show the same pattern. The durability of all valves is unpredictable, even valves that are manufactured in the best conditions. If two pericardial valves of the same type and size are implanted in two patients, there is no way of knowing which one will last longer. Dr. Vilela Batista has described a very elegant way to construct a three-leaflet pericardial valve. I still think it is difficult to manufacture a valve when the aorta is crossclamped, for the reasons that I have described, I do not think this method should be widely used. I see a merit to this method in case a valve is not available. When cost is a major factor, then this method can be a good alternative. I have several questions for Dr. Vilela Batista: How many patients have a diastolic murmur or had reoperation? Were there any children in this series? What was the rate of calcification? DR. ROBERT W. M. FRATER Bronx. N. Y.
The authors have produced an elegant imitation of nature. In particular, their technique takes advantage of the fact that the aortic root is dynamic. John Hunter in the 1760s showed that the aortic valve in diastole is narrower than it is in systole; it widens in systole. He said the diameter increased by one fifth. Stanton Nolan in the 1970s proved this scientifically. That means the difference between a 20 mm and a 24 mm diameter, and it is only a free-form valve of the kind that Dr. Vilela Batista has described that can take advantage of this dynamic aspect of the aortic valve function. I do, however, have misgivings. My colleagues and I have used tanned xenograft pericardium as a free graft within the heart, experimentally and clinically, many times. It certainly heals beautifully. It heals to the papillary muscle, to the aorta, and to the cusp. In young animals it can calcify. In children it thickens. The loss of mobility is not important in many applications, but when xenograft pericardium is used to make a three-cusp valve, it may well be important. As Dr. Carpentier pointed out many years ago, when we mount a biological tissue on a stent, we protect it from the effects of healing; we protect it from the tissues. [Slide] In this lonescu-Shiley valve, explanted after 8 years, one cusp was protected from the effects of tissue ingrowth by
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the stent and this cusp stayed pliable. The other two cusps were reached by the tissue growing in over the stent and were rendered immobile, thickened, and essentially useless. It is my fear that what is obviously a tour de force of Dr. Vilela Batista's in implanting these valves will ultimately be defeated by tissue ingrowth. The very fact that makes it possible for him to implant the tanned xenograft pericardium, namely that tissue heals to leather, is also the fact I suspect that will ultimately render it useless. I hate to sound a critical note, but I would ask Dr. Vilela Batista what he foresees for the future of his freehand xenograft aortic valves. DR. VILELA BATISTA (Closing) Dr. Deac, I agree that this valve should not be called stentless, because we use the "aorta" itself as a stent, as nature has done for millions of years. As to your other question, if any of these sutures have pulled out, the answer is, "No." The reason is that we have left these leaflets more redundant for better cusp coaptation. This way, the blood pressure closes the valve side to side and that takes the tension off the suture line. lt is the same principle as that used for flight: What holds an
Thoracic and Cardiovascular Surgery
airplane in the air is not the wings but the air itself. For another example, if someone is climbing up a well wall alone, he will depend a lot on the strength of his own hand grip (suture line). However, if there are two persons climbing up with their backs against each other, they will do it by just walking up, with no need to use their hands. Dr. Gabbay, there must be a misunderstanding here. We never said this valve is "monocuspid." We said that this valveis monopatch and we form three cusps" as suturing goes along. Consequently it is tricuspid. With regard to gradients, I think that a small postoperative gradient with relatively normal left ventricular function and normal cardiac index is not too important. On the other hand, the same small gradient immediately after the operation with very poor left ventricular function and low cardiac index can be a big problem. Dr. Frater, we have not encountered commissure tissue overgrowth so far. However, we cannot say much about it yet, because we have seen only the one patient with a dissected aorta, and those commissures had healed nicely. I guess even if commissure overgrowth eventually happens it will not cause a gradient because the monopatch's effective valve area is much larger than the effective valve areas of stented valves.