Experience with St. Jude Medical valve prosthesis in children

J

THoRAc CARDIOVASC SURG

1987;93:73-9

Experience with 81. Jude Medical valve prosthesis in children A word of caution regarding right-sided placement Tbirty-six children aged 6 montm to 18 years, underwent insertion of 37 St. Jude Medical cardiac prostheses. In 20, the valve was placed in the aortic or mitral position, and in 16 in the pulmonary or tricuspid position. There was one (2.8 %) hospital death. All patients received maintenance doses of saIicylatesand dipyridamole after the operation. Follow-up data are available for all patients for 12 to 24 postoperative montm. There was no incidence of valve dysfunction or thromboembolic complication in any of the 20 patients with valves in the systemic (left) side of the circulation, and all manifested improvement in their functional class. In contrast, six (37%) of the 16 patients with valves in the pulmonary (right) side of the circulation developed dysfunction of the prosthesis 1 to 6 months after insertion. Prosthesis failure was associated with fibrous tissue growing into the struts, leading to leaflet immobilization. At 2 years, the actuarial functional life was 100% for mitral and aortic valves and 70% for pulmonary and tricuspid valves. The data illustrate the excellent hemodynamic function of the S1.Jude Medical valve in children. The absence of thromboembolic complications warrant continued implantation of the prothesis in the left side without warfarin anticoagulation therapy, but the high incidence of valve dysfunction in the pulmonary position does not justify its continued use in the right side.

Michel N. Ilbawi, M.D., C. Gregory Lockhart, M.D., Farouk S. Idriss, M.D., Serafin Y. DeLeon, M.D., Alexander J. Muster, M.D., C. Elise Duffy, M.D., and Milton H. Paul, M.D., Chicago. Ill.

As the number of children requmng heart valve replacement increases, the need for durable valve substitutes with good hemodynamic performance and low incidence of complications becomes more apparent. The recently developed St. Jude Medical valve prosthesis is a pyrolytic carbon valve designed to minimize thromboembolic phenomena and eliminate the need for anticoagulation therapy.' It has central flow characteristics

From the Divisions of Cardiovascular-Thoracic Surgery and Cardiology. The Children's Memorial Hospital, and the Departments of Surgeryand Pediatrics, Northwestern University Medical School, Chicago, Ill. Research supported in part by the A. C. Buehler Foundation, Park Ridge, Ill. Received for publication Jan. 6, 1986. Accepted for publication Feb. 18, 1986. Address for reprints: Michel N. Ilbawi, M.D., Division of Cardiovascular-ThoracicSurgery, The Children's Memorial Hospital, 2300 Children's Plaza, Chicago, Ill. 60614.

similar to the bioprosthetic valves, and is extremely low in profile so that it does not interfere with cavity volume.' These favorable characteristics have led to its widespread use in children as an alternative to the porcine valve, which has shown a very high incidence of early fibrocalcific degeneration." Experience with the valve in young patients, although limited by the paucity of long-term follow-up, has demonstrated its excellent hemodynamic properties," Controversy, however, still exists over the form of and need for anticoagulation therapy in pediatric patients with this prosthesis. We have encountered several cases of acute dysfunction of the St. Jude Medical valve prosthesis placed in the pulmonary position. This alarmingly high incidence of failure prompted us to review our total experience with the prosthesis in children in an attempt to evaluate its performance, especially in the right side of the circulation, and to establish guidelines for anticoagulation therapy when the valve is used in this age group. 73

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Ilbawi et al.

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Table I. Experience with St. Jude Medical valve Total

8.0 ± 37 87.0 ± 23.0 ± 8 6 12.7 ±

Age at operation (yr) No. of valves Preoperative ejection fraction'[ Valve diameter (mm) Valved conduits Failed prosthesis Duration of follow-up (mo)

Right-sided valves

Left-sided valves

p Value'

10.0 ± 5.9 21 91.0 ± 7.4 23.0 ± 3.0 I

<0.05

7.3 3.0

6.4 ± 4.3 16 85.0 ± 14.5 23.0 ± 3.0 7 6

6.3

12.7 ± 6.9

12.7 ± 6.1

5.5

o

NS NS NS <0.05 NS

Legend: NS. Not significant. 'Right-sided (pulmonary and tricuspid) versus left-sided (mitral and aortic) valves. tExpressed as percent of normal for the related ventricle.

Table II. Patients with prosthetic dysfunction Preop. Patient

Age (yr)

4

I

Lesion

TOF with hypoplastic PA

Postop.

I

Ventricular function'

90%

2

2

Truncus arteriosus

100%

3

~"

TOF with absent PV

92%

4

7

sip Truncus repair Stenotic porcine conduit

60%

5

4

sip TOF repair Severe PI

81%

6

3

TOF with hypoplastic PA

100%

Operation and valve size

Symptoms

I Onset I cardiogram EchoI (wk)

TOF repair PV 19 mm

[Exercise

Truncus repair Conduit 24 mm Total repair PV 19 mm

Absent valve sound

5

Immobile leaflets

Absent valve sound

4

Immobile leaflets

17

Immobtle leaflets

Replacement of RV-PA.~ conduit 24 mm PV insertion 25 mm

[Exercise

16

Leaflets in semi-open position

Absent valve sound

18

Immobile leaflets

Total repair PV 21 mm

Absent valve sound

7

Leaflets in semi-open position

Doppler

Moderate PS (45 mm) Severe PI Mild PS (25 mm) Severe PI Moderate PS (40 mm) Moderate PI Mild PS (30 mm) Severe PI Moderate PS (50 mm) Moderate PI Moderate PS (35 mm) Moderate PI

Outcome

..

Awaiting

operation Conduit replaced; well Valve replaced; well Awaiting operation

Awaiting operation Awaiting operation

Legend: PA. Pulmonary arteries. PI, Pulmonary regurgitation. PS, Pulmonary stenosis. PV, Pulmonary valve. RV, Right ventricle. sip, Statuspost. TOF, Tetralogy of Fallot. 'Ventricular function expressed as percent of normal ejection fraction of the related ventricle.

Patients and methods Between January 1983 and January 1985, 36 patients, aged 6 months to 18 years (mean 8.0 ± 5.5 years), underwent insertion of the St. Jude Medical cardiac valve prosthesis (Table I). Aortic valve replacement was performed in nine patients. The indications were congenital aortic stenosis in six, all of whom had undergone previous valvotomy or porcine valve insertion; severe aortic regurgitation secondary to prolapsing aortic valve cusp into a ventricular septal defect in two; and bacterial endocarditis in one. Mitral valve or left-sided atrioventricular valve replace-

ment was performed in nine patients. Underlying lesions were congenital mitral regurgitation in three, valvular insufficiency after repair of endocardial cushion defect in two, regurgitation caused by bacterial endocarditis in one, and tricuspid valve abnormalities associated with transposition in the remaining three. Pulmonary valve insertion was performed in eight patients because of significant pulmonary regurgitation and right ventricular dysfunction after repair of tetralogy of Fallot. Two of these patients have had absent pulmonary valve syndrome. Tricuspid valve insertion, as a part of a modified Fontan operation, was done in one

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patient with pulmonary atresia and intact ventricular septum. Concurrent double valve replacement (aortic and mitral) was performed in one case because of severe valvular insufficiency secondary to mucocutaneous lymph node syndrome (Kawasaki disease). St. Jude Medical valved conduits were used in eight patients, five of whom had a degenerated porcine valve conduit. A left ventricle-aorta conduit was used to bypass an outflow obstruction caused by abnormal mitral valve attachments in one patient with atrioventricular septal defect; and right ventricle-pulmonary arteryconduits were utilized in the repair of pulmonary atresia with ventricular septal defect in three, truncus arteriosus in three, and transposition of the great arteries with ventricular septal defect and pulmonary stenosis in one patient. Midstemotomy approach was used in all patients. The procedure was performed using cardiopulmonary bypass with hollow-fiber oxygenator, moderate hypothermia (25° to 28° C), and hemodilution. Cold blood cardioplegic solution infused into the aortic root at 4 ° C combined with topical hypothermia (iced saline solution) was used for myocardial protection. The prosthesis was secured in place by interrupted mattress sutures with Dacron pledgets. In cases of pulmonary valve insertion, the anulus was enlarged with a patch to accommodate the largest valve possible.' The techniques used for the insertion of right ventricle-pulmonary artery or left ventricle-aorta conduits have been previously reported." 9 All patients received maintenance doses of salicylates (aspirin) 10 mg/kg/day and dipyridamole (Persantine) 2.5 to 5 rug/kg/day after the operation. Serial postoperative echocardiograms and Doppler studies to evaluate pressure gradients and valve function were performed in all surviving patients at 6 month intervals. 10. 11 Valve dysfunction was defined as the appearance of a new significant systolic or diastolic murmur confirmed byechocardiography to originate from impaired motion of the prosthetic valve leaflets, and associated with a significant pressure gradient across the valve (>30 torr for aortic and pulmonary valves, and >5 torr for mitral and tricuspid valves). The incidence of valve-related problems was expressed by actuarial methods described by Grunkemeier and Starr," and confidence limits were determined by the method of Bodnar and associates." Comparison between continuous variables for two groups was made with the unpaired t test. Discrete variables were compared by means of chi square analysis by Fisher's exact test. A value of p < 0.05 was considered significant.

St. Jude Medical valve placement in children

75

Right Sided Valves

II

tTIJ

Pre-Op

III

~

IV

Fig. 1. Functional class of 28 patients before and after St. Jude Medical valve insertion. Absence of improvement in four patients with right-sided valves reflects prosthetic dysfunction. N.Y.H.A., New York Heart Association.

Results One (2.8%) of the 36 patients died: a 13-year old patient with advanced myocardial disease (Class III) secondary to severe aortic stenosis and insufficiency caused by a degenerated porcine valve. Follow-up is available on all survivors 12 to 24 months after operation, for a total of 516 months to aggregate risk. There were no late deaths, prosthetic endocarditis, or valverelated hemolysis. There was no incidence of valvular insufficiency, stenosis, or thromboembolic complication in any of the 20 patients with valves in the left (systemic) side of the circulation (mitral or aortic position), and all have manifested improvement in their functional class (Fig. 1). In contrast, six (37%) of the 16 patients with valves in the right (pulmonary) side of the circulation (pulmonary and tricuspid position) manifested acute dysfunction of the prosthesis 1 to 6 months after insertion (Table II). In one, the valve was within a right ventricle-pulmonary artery conduit. In the remaining five, it was in the pulmonary valve position. Echocardiography performed in these six patients demonstrated the impaired valve leaflet motion (Fig. 2). Cardiac catheterization and angiography in three patients confirmed the lack of leaflet movement and the presence of valvular stenosis and insufficiency (Fig. 3). Two patients underwent repeat operation; the remaining four are awaiting operation. Intraoperative inspection of the valves revealed similar pathologic findings. There was fibrous ingrowth from the anulus of the valve into the two short struts, impairing the movement of the leaflets and resulting in their fixation in the semi-open position (Fig. 4). The valves were replaced with porcine

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Ilbawi et al.

Thoracic and Cardiovascular Surgery

Fig. 2. Modified parasternal echocardiographic view (A) and Doppler wave tracing (B) in a patient with a malfunctioning St. Jude Medical valve (arrows) illustrating prosthetic stenosis and regurgitation. LA = Left atrium. C = conduit.

Fig. 3. Angiographic appearance of St. Jude Medical valve stuck in the semi-open position. Visualization of the right ventricle during diastolic is secondary to valvular insufficiency. A, Systole. B, Diastolic. MPAC = Right ventricle-pulmonary artery conduit. RVOT = Right ventricular outflow tract. a = Anterior leaflet. p = Posterior leaflet.

bioprostheses, and the patients had uneventful recoveries. There was no relationship between the incidence of valve malfunction and its size (Fig. 5). The calculated actuarial functional life of the St. Jude Medical valve at 2 years was 70% ± 11% in the right side and 100% in the left side of the circulation (Fig. 6).

Discussion

Valve replacement in children presents a unique constellation of considerations. 14 The size of the pediatric heart requires the placement of a prosthetic valve with the lowest profile and the largest orifice possibleso that it can accommodate the increasing flow requirements as the child grows. Prosthesis durability is important

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St. Jude Medical valve placement in children

January 1987

77

Fig. 4. Gross appearance of malfunctioning St. Jude Medical prosthesis. Note the fibrous tissue build-up (arrows) around the struts and into the hinges, resulting in leaflet immobilization. Process is limited to the periphery of the valve.

10

'~"

~

Left Sided Valves

• ·i

Right Sided Valves

•

Dysfunctional Valves

i3 2

::; c;; c a a

Q;

nc

E

c;;

(;

5

Right Sided Valves

La

::J

U.

D

:J

Lt

20

18

15

9

6

Rt

13

10

10

10

8

8

12

16

20

3

.~

Z

::J

ti

« Valve Diameter (rnrn)

4

Period of Follow-Up (Mos)

Fig. 5. Distribution of the valves used according to size and location. Smaller valves were not associated with an increased incidence of malfunction.

Fig. 6. Actuarial functional life (event-free performance) of St. Jude Medical valve in children.

because these patients have a long life expectancy. Multiple valve replacements over the course of 20 to 40 years, although much safer today, still carry the significant risks associated with reoperation. Anticoagulation therapy, which has been necessary with most mechanical heart valves, is another problem. The use of anticoagulants such as warfarin is difficult to control in the active child and presents well-documented risks in the young woman of childbearing age. Theuse of porcine xenografts was thought initially to obviate these problems. The incidence of valve failure, thromboembolism, hemolysis, and endocarditis was minimal. In recent years, however, there have been numerous reports of early fibrocalcific degeneration of bioprostheses placed in the mitral or aortic valve position in children. IS The causes of the accelerated failure in this age group, although not well defined, are multiple, and probably related to accelerated calcium metabolism, exaggerated immunologic responses, and turbulent

blood flow as a result of the relatively small valve size causing microtrauma to the valve leaflets.7 The high incidence of early porcine valve failure has led to a search for a better alternative in pediatric patients. The good hemodynamic characteristics and the long history of dependability of the 51. Jude Medical valve in adults resulted in its widespread use in children.":" Pass and associates" reported the implantation of 51. Jude Medical mechanical valves in 34 patients younger than 21 years of age who were observed for I to 50 months without the use of any anticoagulation therapy. All 31 patients with aortic or mitral valve prostheses manifested hemodynamic improvement, and questionable thrombosis developed in only one (3.5%). Our experience, although limited by the short follow-up period, emphasizes the excellent hemodynamic properties of the valve and the lack of thromboembolic complications when placed in the mitral or aortic position.

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78

Ilbawi et al.

In contrast and of major concern, St. Jude Medical valves placed in the pulmonary (right side) circulation did not perform as well as those in the systemic (left) side) circulation. One of the three (33%) valves in the pulmonary position reported by Pass" and six (37%) of the 16 right-sided valves in our experience developed early malfunction." This discrepancy in the performance of the valve depending on its implantation site raises questions concerning the cause of the problem. The early onset of valve failure might suggest the possibility of thrombus formation. However, the pattern of valve dysfunction in our two patients who underwent repeat operation consisted primarily of pannus ingrowth into the strut of the valve and secondary impairment of the hinge mechanism and leaflet movement. The histologic sections of the invading tissue revealed fibrous and inflammatory tissue without evidence of fibrin or platelet deposition, indicating that the primary pathologic process is probably not clotting but tissue overgrowth." Similar observations have been reported by Moulton," Bowen," Nunez," and their colleagues. The problem of tissue overgrowth as a cause of valve dysfunction appears to be more common in the younger patient population and has been emphasized previously.s"-" Regardless of whether clot formation or tissue invasion starts the process, it seems that the low profile structure of the St. Jude Medical valve predisposes to extension of the fibrous tissue into the delicate hinge mechanism. The relatively lower pressure and bloodstream velocity on the right side of the circulation allow such a build-up of tissue to occur on valves placed in the pulmonary or tricuspid position. In contrast, the higher left or systemic ventricular pressure results in a more forceful opening and closing of the leaflet and retards any tissue ingrowth into the valve, explaining the absence of prosthetic failure in the left side. Whether pediatric patients with St. Jude Medical valve prostheses should receive anticoagulation therapy with warfarin products or merely receive salicylates plus dipyridamole is not yet completely understood. Previous experiences with prosthetic valves in children suggest that thromboembolic complications are less likely in this age group," 27-30 Although no specific explanation for this low incidence of valve thrombosis has developed, it is likely that the relatively higher cardiac output, the faster heart rate, the lack of atrial arrhythmias, and the presence of good ventricular function may all playa role." The occasional reported cases of thrombosis or embolization of the St. Jude Medical valve have occurred with and without anticoagulation therapy and were mainly in older patients in whom atrial arrhythmias and ventricular dysfunction are common." Our

Thoracic and Cardiovascular Surgery

data, and those of Pass," Borkon, J3 and their associates indicate that antiplatelet therapy alone is sufficient to prevent the thromboembolic complications of St. Jude Medical valve prosthesis in young patients who have sinus rhythm and good myocardial function if the valve is used in the left (systemic) side of the circulation. The data also indicate that this form of therapy is not effective in preventing prosthesis dysfunction in patients with right-sided valves. The value of warfarin anticoagulation therapy in the latter group of patients remains speculative, because it is more likely that the initiating process of valve failure in the pulmonary position is tissue growth rather than clot formation. Although the follow-up period is still too short to draw definitive conclusions, the excellent hemodynamic performance of the St. Jude Medical valve in the young patient and the very low incidence of thromboembolic or hemorrhagic complications warrant its continued use in the mitral or aortic valve position without warfarin anticoagulation therapy." The use of this valve in the right side, however, is associated with frequent mechanical failure and therefore should be discouraged. The good long-term durability of the porcine valves when placed in the pulmonary and the tricuspid positions, excluding those in conduits, in our experience and in the experience of others, and the recent improvements in its preservation and mounting techniques, justify its use for pulmonary and tricuspid valve replacement. 7.34

2

3

4 5

6 7

REFERENCES Horstkotte D, Korfer R, Seipel L, Bircks W, Loogen F: Late complications in patients with Bjork-Shiley and St. Jude Medical heart valve replacement. Circulation 68:Suppl 2:175-184, 1983 Hehrlein FW, Gottwik M, Fraedrich G, Mulch J: First clinicalexperiencewith a new all-pyrolytic carbon bileaflet heart valve prosthesis. J THORAC CARDIOVASC SURG 79:632-636, 1980 Geha AS, Laks H, Stansel HC, Cornhill JF, Kilman JW, Buckley MJ, Roberts WC: Late failure of porcine valve heterografts in children. J THORAC CARDIOVASC SURG 78:351-365, 1979 Kutche LM, Oyer P, Shumway N, Baum D: An important complication of Hancock mitral valve replacementin children. Circulation 60:Suppl:98-103, 1979 William DB, DanielsonGK, McGoon DC, Puga FJ, Mair DD, Edwards WD: Porcine heterograft valve replacement in children. J THORAC CARDIOVASC SURG 84:446-450, 1982 Gardner T, Roland JM, Neill C, Donahoo 1: Valve replacement in children. A fifteen-year experience. J THORAe CARDIOVASC SURG 83: 178-185, 1982 I1bawi MN, Idriss FS, DeLeon SY, Muster AJ, BerryTE, Paul MH: Long-term results of porcine valve insertion for

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St. Jude Medical valve placement in children

January 1987

pulmonary regurgitation following tetralogy repair. Ann Thorac Surg 41:478-482, 1986 8 McGoon DC, Rastelli G, Ongley PA: An operation for the correction of truncus arteriosus. JAMA 205:69-73, 1968 9 Norman JC, Cooley D, Hallman G, Nihill M: Left ventricular apical-abdominal aortic conduits for left ventricular outflow tract obstructions. Clinical results in 11 patients with a special composite prosthesis. Circulation 56:Suppl 2:62-65, 1977 10 Depace N, Kotler M, Mintz G, Lichtenberg R, Goel I, Segal B: Echocardiographic and phonocardiographic assessment of the St. Jude cardiac valve prosthesis. Chest 80:272-284, 1981 II Panidis I, Ren J, Kotler M, Mintz G, Mundth E, Goel I, Ross J: Clinical and echocardiographic evaluation of the St. Jude cardiac valve prosthesis. Follow-up of 126 patients. J Am Coli Cardiol 4:454-462, 1984 12 Grunkemeier GL, Starr A: Actuarial analysis of surgical results. Rationale and methods. Ann Thorac Surg 24:404408, 1977 13 Bodnar E, Haberman S, Wain WH: Comparative method for actuarial analysis of cardiac valve replacement. Br Heart J 42:541-552, 1979 14 Berry BE, Ritter DG, Wallace RB, McGoon DC, Danielson GK: Cardiac valve replacement in children. J THORAC CARDIOVASC SURG 68:705-710,1974 15 Dunn JM: Porcine valve durability in children. Ann Thorac Surg 32:357-368, 1981 16 Baudet E, Oca C, Roques X, Laborde M, Hafez A, Collot M, Ghidoni I: A 5Y2 year experience with the St. Jude Medical cardiac prosthesis. J THORAC CARDIOVASC SURG 90:137-144,1985 17 Czer L, Metlaff J, Chaux A, DeRobertis M, Yagonathan A, Gray R: A six year experience with the St. Jude Medical valve. Hemodynamic performance, surgical results, biocompatibility and follow-up. J Am Coli Cardiol 6:904-912, 1985 18 Singh A, Christian F, Williams D, Cuores C, Riley R, Nanian K, Karlson K: Follow-up assessment of St. Jude Medical prosthesis valve in the tricuspid position. Clinical and hemodynamic results. Ann Thorac Surg 37:324-327, 1984 19 Chaux A, Czer LSC, Maltoff JM, DeRobertis M, Stewart M, Bateman T, Kass R, Lee M, Gray R: The St. Jude Medical bileaflet valve prosthesis. A five year experience. J THORAC CARDIOVASC SURG 88:706-717,1984 20 Pass H, Sade R, Crawford F, Hohn A: Cardiac valve prosthesis in children without anticoagulation. J THORAC CARDIOVASC SURG 87:832-835, 1984 21 Nunez L, Iglesias A, Sotillo J: Entrapment of leaflet of St.

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is 29

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32

33

34

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Jude Medical cardiac valve prosthesis by miniscule thrombus. Report of two cases. Ann Thorac Surg 29:567-569, 1980 Moulton AL, Singleton RT, Oster WF, Bosley J, Mergner W: Fatal thrombosis of an aortic St. Jude Medical valve despite "adequate" anticoagulation. Anatomic and technical considerations (letter). J THORAC CARDIOVASC SURG 83:472-473, 1982 Bowen TE, Tri TB, Worthman DC: Thrombosis of a St. Jude Medical tricuspid prosthesis. J THORAC CARDIOVASC SURG 82:257-262, 1981 Nunez L, Iglesias A, Sotillo J: Entrapment of leaflet of St. Jude Medical cardiac valve prosthesis by miniscule thrombus. Report of two cases. Ann Thorac Surg 29:566-569, 1980 Williams WG, Pollock JC, Geiss DM, Trusler GA, Fowler RS: Experience with aortic or mitral valve replacement in children. J THORAC CARDIOVASC SURG 81:326-333, 1981 Friedman S, Edmunds LH Jr, Cusso CC: Long-term mitral valve replacement in young children. Influence of somatic growth on prosthetic valve adequacy. Circulation 57:981-986, 1978 Iyer KS, Reddy S, Rao M, Venugopal P, Bhatia ML, Gopinath N: Valve replacement under twenty years of age. Experience with the Bjork-Shiley prosthesis. J THORAC CARDIOVASC SURG 88:217-224, 1984 Rufilanachas 11, Jaffe A, Miranda AL, Tellez G, Arosti J, Maronas JM, Figueroa D: Cardiac valve replacement with the Bjork-Shiley valve in young patients. Scand J Thorac Cardiovasc Surg 11: 11-14, 1977 Chen S, Laks H, Fagan L, Terchluse D, Kaiser G, Barner H, William VL: Valve replacement in children. Circulation 56:SuppI2:117-121, 1977 Stansel HC Jr, Nudel DB, Berman MA, Tolner NS: Prosthetic valve replacement in children. Arch Surg 110:1397-1400, 1975 Ebert P: Discussion of Gardner T, Roland JM, Neill C, Donahoo J: Valve replacement in children. A fifteen-year experience. J THORAC CARDIOVASC SURG 83:178-185, 1982 Commerford P, Lloyd BM, DeNobrege A: Thrombosis of St. Jude Medical cardiac valve in the mitral position. Chest 80:326-327, 1981 Borkon MA, Reitz BA, Gardner T: Five year follow-up of St. Jude Medical valve replacement in infants and children (abstr). Circulation 72:Suppl 3:149, 1985 Reiland J, Perier P, Leconte B: The third generation Carpentier-Edwards bioprosthesis. Early results. J Am Coli Cardiol 6:1149-1154, 1985