Surgical Treatment of Valvular Heart Disease
Lawrence H. Cohn, MD, Boston, Massachusetts
A review of valvular heart surgery has relevance to Doctor J. Englebert Dunphy’s distinguished surgical career? As a student, house officer, and professor he was closely associated with surgeons who made significant advances in the treatment of valvular heart surgery. As a student at the Harvard Medical School he worked in the clinic of Doctor Harvey Cushing, Professor of Surgery at the Peter Bent Brigham Hospital, who performed some of the first experiments to produce and correct mitral stenosis [I]. As a resident in surgery at the Peter Bent Brigham Hospital, Doctor Dunphy worked with Doctor Elliot Cutler, who performed the first successful clinical mitral valve operation in 1923 [2]. As a member of the senior staff of the hospital, he worked with Doctor Dwight Harken, who performed one of the first series of closed mitral commissurotomies [3] and developed the concept of the ball and cage heart valve [4]. Finally, while Doctor Dunphy was Chairman of Surgery at the University of Oregon, Doctor Albert Starr developed and successfully implanted the first consistently reliable heart valve prosthesis [5]. Historic Review
Surgical treatment of diseased human heart valves was first discussed by Sir Lauder Brunton [6] in the Lancet in 1902. His observations on human cadavers indicated that mitral stenosis might be correctable by merely cutting the stenosed commissures with a
From the Department of Surgery, Division of Thoracic and Cardiac Surgery, Harvard Medical School, and Peter Bent Brigham Hospital, Boston, Massachusetts. Reprint requests should be addressed to Lawrence H. Cohn, MD, Department of Surgery, Peter Bent Brigham Hospital, 721 Huntington Avenue, Boston, Massachusetts 02115. Presented in part at the Sixty-Second American College of Surgeons Cardiovascular Surgical Postgraduate Course, 1976.
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knife inserted via the chambers of the heart. Although his suggestion was rebuked in the next issue of the Lancet [7], it stimulated interest in the pathophysiology and surgical treatment of valvular heart disease. During 1902 to 1923 a number of surgical investigators, including Cushing and Branch [1] and Allen and Graham [a], performed experiments to surgically create and correct mitral stenosis. Cutler, Levine, and Beck [9] also performed basic cardiac surgical experiments to determine the amount of operative trauma that the heart could withstand. Cutler and Levine [2] by 1923 had formulated their concept of the pathology of mitral stenosis, concluding that there was a mechanical obstruction that could be corrected by excision of a segment from the valve; therefore, Beck and Cutler [IO] developed a special instrument, the cardiovalvulotome. (Figure 1.) They believed that the congestive failure associated with mitral stenosis was due to the mechanical obstruction of the valve rather than myocardial disease, the commonly held theory of the time, Cutler and Levine in May 1923 operated on their first patient, a twelve year old girl dying of mitral stenosis. After median sternotomy, Doctor Cutler inserted a tenotomy knife (his cardiovalvulotome had not yet arrived) through the apex of the left ventricle and bindly cut both mitral commissures. The patient survived, recovered, and lived for four and a half years [2]. Cutler performed six additional operations in the 192Os, using his cardiovalvulotome; all six patients died in the immediate postoperative period from massive mitral regurgitation. In 1925, two years after Cutler’s first operation, an important operation was performed by Henry Souttar [II] at the London Hospital (ironically, the hospital of Sir Brunton): he inserted his index finger through the atria1 appendage to enlarge the opening in the mitral valve. Despite the suc-
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cessful outcome, he received no further patients. Cutler and Beck [12] in 1929 reviewed all twelve patients with cardiac valvular disease operated on to that time and suggested a moratorium because of the high mortality. The amount of valve tissue removed with the cardiovalvulotome had created deleterious mitral regurgitation. However, they prophetically suggested that Souttar’s finger fracture technic might eventually prove to be the best. In 1948, Harken et al [3] began performing mitral valvuloplasties at the Peter Bent Brigham Hospital, utilizing the left atria1 approach. At the same time, Charles Bailey [12A] of Philadelphia began his series of closed mitral operations. These surgeons began the “modern” era of cardiac surgery, and from 1948 to date there has been continuous modification and improvement in the treatment of valvular heart disease. After the development of the heart-lung machine in 1953 by Gibbon, surgeons debrided calcific aortic valves and inserted a small number of artificial leaflet valves or implanted Hufnagle’s ball and cage valve in the descending aorta for partial correction of aortic regurgitation [13]. These operations were only moderately successful and for only a small number of carefully selected patients. The first artificial ball and cage aortic valve for the subcoronary position was conceived, fabricated, and implanted by Harken et al [4] in 1959. The first series of successful aortic and mitral valve prosthetic replacements was accomplished by Starr and Edwards [5] in 1960 using the Starr-Edwards ball and cage valve. This achievement opened the way for effective treatment of large numbers of patients with severe valvular heart disease with a hemodynamically safe and durable prosthetic device. Subsequently, low profile disc and cage valves [14] and tilting disc central flow valves [15] were developed with improved hemodynamics. Concurrent with the development of prosthetic heart valves, homograft tissue heart valves were developed because of their decreased proclivity to thromboemboli. In 1956, Murray [16] placed fresh homograft aortic valves in the descending thoracic aorta, which were found to be still functioning normally seven years later [ 171. In 1960, Barrett-Boyes [18] and Ross [19] began performing subcoronary aortic valve replacement with free sewn homografts. However, the valves, prepared and sterilized by a variety of chemicals, lacked durability, causing high reoperation rates. Fresh, antibiotic-treated homografts [20,21] or frozen, irradiated valves [22] were more durable, but the late failure rates led to the discontinuation of homograft valve replacement except in special situations. In 1965, after experi-
Volume 135, March 1370
mental work by Binet, Carpentier, and Langlois [23], porcine heterograft valves were sterilized with formaldehyde and sewn on stents for clinical valve replacement [24]; however, frequent early graft failure from collagen disruption made this form of preservation unacceptable [25]. In 1968, Carpentier, Lemaigre, and Robert [26] fixed and sterilized porcine heart valves in glutaraldehyde and documented satisfactory six year durability. In 1969 Reis et al [27] fabricated a semiflexible valve stent upon which porcine heterografts treated with a special glutaraldehyde process were sewn. The Hancock valve, now widely used, became the first quality-controlled, mass-produced tissue valve. Other forms of biologic material utilized for fabrication of cardiac valves have included fascia lata [28], homologous dura mater [29], and heterologous glutaraldehyde-fixed pericardium [30]. The last two of these have been successfully used by their originators for more than five years with excellent durability, low incidence of thromboembolism, and satisfactory hemodynamic performance. Evaluation of Cardiac Valve Devices
If surgery results in satisfactory hemodynamic performance, it is preferable to preserve and reconstruct the patient’s own valve whenever possible because the ideal replacement valve has not yet been developed. Since the development sixteen years ago of the first reliable device for valve replacement, one fact has emerged: for patients with severe valvular heart lesions, long-term survival after aortic, mitral, or multiple valve replacement is superior to that after medical treatment [31]. Following is an evaluation of the durability, thromboembolic potential, and hemodynamic per-
Figure 1. The cardiovalvulotome circa 1923.
of Doctor Elliot Cut/er,
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formance of the ball and cage valve, tilting disc, and glutaraldehyde-treated porcine xenograft. Durabllity
Aortic Values. (Table I). Of all heart valves presently in use, the Starr-Edwards bare strut ball valve model 1260, developed in 1965 after the first StarrEdwards valve demonstrated silicone ball variance from cholesterol absorption [32], has the longest continuous durability record. The cloth-covered Starr-Edwards valve was introduced in 1967 to reduce the incidence of thromboembolism, because experimental data [33] suggested that the struts might become endothelialized. This valve, however, introduced new durability problems from cloth wear and hemolysis, requiring several model changes; the incidence of reoperations for these complications was estimated at 10 per cent at five years [34,35]. The Smeloff-Cutter full orifice bare strut ball and cage valve [36], developed in 1966, had a slightly better hemodynamic performance than the StarrEdwards valve. It has been used for ten years and has an excellent durability record [37,38] and no ball variance. In 1969 the low profile semicentral flow disc valves were introduced to improve the effective orifice area and relieve obstruction at secondary and tertiary outflow areas (39,401. The Bjork-Shiley tilting disc valve now employs a pyrolite-occluding disc, after initially using a delrin disc which was discontinued
TABLE I
because of fatigue problems [41,42]. The LilleheiKaster tilting disc valve, although similar in design, has a theoretical hemodynamic advantage because the disc occluder opens to a more central position. Durability of these aortic valves has been uniformly good, with no reported cases of valve dysfunction [43,44]. The Hancock glutaraldehyde-stabilized porcine heterograft valve has been reliable in the aortic position since 1970, and actuarial survival data have been equal to those of artificial prosthetic valves [45-471. A recent postoperative pathologic examination of Hancock aortic valves by Fishbein et al [48] indicated that in the absence of infection, collagen durability is satisfactory to 6 years. They observed only one abnormal aortic valve in a patient on chronic dialysis who developed microscopic valvular calcification. Mitral Values. Table II summarizes actuarial survival data on the following mitral prostheses currently in use: Starr-Edwards valve [34,49], Smeloff-Cutter valve [50,51], Beall disc and cage [52,53], Bjork-Shiley valve [42,54], Lillehei-Kaster valve [43,44], and Hancock porcine xenograft [45,47,55]. Strut cloth wear of the Starr-Edwards valve, a significant problem in the aortic position, has not occurred with the mitral prosthesis. Acceptable durability and patient survival have been achieved with the Hancock porcine valve; a 0.1 per cent incidence of primary valvular dysfunction has occurred with
Aortic Valve Replacement Devices
Valve S-E 1260 2310 2400 S-E 1260 S-C S-C B-S B-S L-K L-K Hancock Hancock
Authors Bonchek and Starr [34] Barnhorst et al [ 351 Davey and Smeloff [ 371 Lee, Barr, and Callaghan [ 381 Stalpaert and Daenen [ 421 Bjork. Henze, and Holmgren [ 4 I] Starek, McLaurin, and Wilcox [ 431 Mitha et al [ 441 Stinson et al [ 451 Cohn, Sanders, and Collins [46]
No. of Patients
Years FU
(%)
Emboli1100 Patient-Years
132 116 132 962 160 187
9 6 2.5 0 10 8
72’ 80’ 73’ 65’ 90’ 60
4.2 0 anticoagI8.8no a/c 6.1 3.5 1.0+ 3.6
140
5
90
0.7+
160
5
86
1.5
61
5
95
0
3 4 3.5
a2 91 04
6.0 2.1 1.0
49 167 71
Survival
Note: Representative clinical series of 5 most popular aortic valves prostheses. S-E = Starr-Edwards; S-C = Smeloff-Cutter; B-S = Bjork-Shiley; L-K = Lillehei-Kaster. Operative mortality omitted. + Estimate. l
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approximately 30,000 such valves in clinical use. In our own experience with 250 Hancock mitral valves, there has been one primary tissue failure due to a torn leaflet from the strut of the flexible stent in a mitral valve in place for eighteen months [48]. Hannah and Reis [57] and Levitsky [58] have documented a total of five cases of primary tissue fatigue. lhromboembolism
Despite improvements in valve durability, thromboembolism continues to be a significant problem, particularly in patients with replacement of the mitral valve. Warfarin anticoagulation, which has an estimated yearly morbidity and mortality of 1 per cent, has been necessary for all patients with prosthetic valves. The incidence of thromboembolic complications is expressed as the number of thromboemboli per 100 patient-years of follow-up. Aortic Values. Thrombolic complications with ball valves, tilting disc valves, and porcine bioprosthetic valves are indicated in Table I. The addition of a cloth covering to the Starr-Edwards valve decreased the incidence of thromboembolism; however, patients with these valves still require long-term anticoagulation [34]. Even though tilting disc valves have had a low incidence of thromboembolism, totally thrombosed Bjork-Shiley and Lillehei-Kaster aortic valves have been reported [46,59]. Discontinuation
TABLE II
Mitral
or change in the regimen of chronic anticoagulation seems to precipitate this event, and thrombectomy is the treatment of choice [59]. Patients with porcine aortic valves have not undergone anticoagulation and their rate of thromboembolism is low, typical of tissue valves in the aortic position. In the Brigham series of 152 Hancock aortic valve replacements, one seventy year old patient in chronic atria1 fibrillation had a nonfatal embolus and one eighty year old man who was taking estrogens for prostatic carcinoma had fatal thrombotic stenosis [46]. Mitral Values. Table II shows the thromboembolic rate for the ball and cage valve, disc and cage, tilting disc, and porcine valve. The ball and cage valve with cloth-covered struts produces emboli less often than the bare strut ball valve, but it still requires anticoagulation. Nonfatal emboli are uncommon with the tilting disc valve, but the rate of total thrombosis has been relatively high. The 10 per cent reported incidence of massive thrombosis of the Lillehei-Kaster valve [43,44] was perhaps due to insertion of too large a prosthesis. Mitral bioprosthetic valves have the lowest incidence of thromboemboli even when most patients do not undergo long-term anticoagulation. It is important, however, to emphasize that in patients with an enlarged left atrium and chronic atria1 fibrillation, particularly those with preoperative mitral regurgitation, the incidence of thromboemboli after tissue valve replacement is similar to that of
Valve Replacement Devices
Valve S-E 6120 6310 6400 S-E 6120 s-c s-c Beall Beall B-S B-S L-K L-K Hancock Hancock
No. of Patients
Authors Bonchek and Starr [34] Barnhorst et al [ 491 Fishman et al [ 501 Oxman, Connolly, and Ellis [ 5 I] Beall et al [ 52] Salomon, Steele, and Paton [ 531 Stalpaert and Daenen Lepley et al [ 541 Mitha et al [ 441 Starek, McLaurin, and Wilcox [ 431 Stinson et al [45] Cohn, Sanders, and Collins [ 551
[ 421
Years Followed
Survival (%)
Emboli/lOO Patient-Years
64 171 90 311 132 79
9 5 2 6 5 6
75’ 80’ 89’ 80’ 60 70
6.0 1.5 8.8 7.4 8.0 6.1
100 76
2 5
87 89
4.0 1.1’
117 242 75 59
5 5 4 4
78 89’ 78 86
1.o+ 1.5 7+
244 56
4.5 4
85 94
5.3 1.6
6.7
Note: Representative clinical series of the commonly used mitral prosthetic and bioprosthetic valves. S-E = Starr-Edwards: S-C = Smeloff-Cutter; B-S = Bjork-Shiley; L-K = Lillehei-Kaster. Operative mortality omitted. + Estimate. l
Volums 135, March 1978
447
Cohn
cs 24
j
0
6
12
18
MONTHS
c 48
II
36
36
AFTER
42
I
1
54
60
66
patients with artificial prosthetic valves [55]. Under these circumstances, long-term anticoagulation should be used regardless of the type of valve employed: the emboli are a consequence of the cardiac lesion rather than the type of valvular prosthesis. In our experience with the Harken disc valve and the Hancock porcine heterograft (Figure 2), patients who maintained a sinus rhythm postoperatively had a significantly lower incidence of thromboembolism if they had a porcine valve (no anticoagulants). If patients were in chronic atria1 fibrillation postoperatively, there was no difference between the Hancock and Harken valves in the incidence of thromboembolism over the four year follow-up period [55].
OPERATION
Figure 2A. Overall incidence of emboii in patients undergoing mitral valve replacement wifh porcine or disc valve.
Hemodynamics
All prosthetic and bioprosthetic valves produce varying degrees of hemodynamic obstruction, depending upon the size of the annulus diameter, the patient’s cardiac output, and the effective orifice area of the valve. A considerable amount of hemodynamic data have been accumulated from patients with ball, tilting disc, and tissue valves; over a wide range of diameters, they are generally nonobstructive, except when the annulus is small. In vitro studies of aortic and atrioventricular valves have shown that most valves are effective in relieving hemodynamic obstructions over a wide range of heart rates and flows
W’l.
65 f f 0
I,,
6
12
16
*
24
MONTHS
*
30
I1
1..
36
42
AFTER
48
,
64
60
66
OPERATION
Figure 28. Incidence of emboli in patients wifh postoperafive sinus rhythm after porcine or disc mitral valve re-
Aortic Valves. A small aortic annulus may produce hemodynamic obstruction with some heart valves. In addition, when the aortic root is small, hemodynamic obstruction may occur at the secondary and tertiary orifices above the aortic annulus. These areas may become obstructed with high profile valves, such as ball and cage valves, unless the aorta is patched with a prosthetic gussett. The Bjork-Shiley and Lillehei-Kaster central flow valves have the lowest transvalvular gradients and the largest effective orifice areas at any annulus diameter and are currently favored by many surgeons when a small annulus is encountered. This can be
TABLE III
Prosthetic Aortic Valves
a@ 85.
0
-
6
12
18
24
MONTHS
30 AFTER
36
42
48
64
60
66
OPERATION
Figure 2C. Incidence of emboii in patients with postoperative chronic afriai fibrillation after porcine or disc valve repiacemenf. (Figures 2A, B, and C reproduced wifh permission from the American Heart Association from [ 551,
44%
Valve
Size
Annulus Diameter (mm)
Bjork-Shiley Lillehei-Kaster Starr-Edwards Smeloff-Cutter Starr-Edwards
19 l4A 8A A2 9A
19 21 21 21 23
0 DISC & (11.27)
Note: Abstracted from
Effective Orifice Area (cm? 1.50 1.50 1.41 1.54 1.70
[ 6 I].
The American Journal of Surgery
Valvular Heart Disease
F/gure 3. Modified orifice Hancock aotiic valve and standard model Hancock aotiic valve (ieft hand). Free-sewn leaflet replaces septai muscle bar of right coronary leaflet a//owing complete mobiiity with systo/e.
Summary
appreciated by comparing diameters of various prosthetic valves in Table III (abstracted from Roschke and Harrison [61]). Hannah and Reis [58], Jones, Craver, and Hatcher [62], and Cohn, Sanders, and Collins [46] documented significant transvalvular gradients in the 21 and 23 mm sizes of the conventional Hancock aortic valve. The gradients are due to the immobile right ventricular muscle on the inferior aspect of the right coronary leaflet. Thus, the smaller the valve, the more obstruction caused by this fixed segment. Recently, Hancock Laboratories modified the aortic valve by removing the muscular cusp and inserting a free-sewn nonmuscular cusp from another porcine aortic valve into the stent. This arrangement has the effect of allowing all three cusps to open completely during systole, thus obviating hemodynamic obstruction [63]. (Figure 3.) Mitral Valves. Hemodynamic obstruction of prosthetic mitral valves is uncommon in adults unless: (1)thrombotic obstruction occurs; (2) there is annular dysproportion (a large individual with a high cardiac output and a congenitally small tissue annulus); or (3) too large a valve is placed in a patient with a small left ventricular cavity [64], a factor which may be responsible for valve thromboses. The Hancock porcine mitral valve behaves in a similar fashion hemodynamically at rest and exercise as the artificial prosthetic valve of the same size [57,65]. In children with endocardial cushion defects or aortic valve endocarditis, hemodynamic obstruction by an artificial or tissue valve may be significant. This has stimulated fabrication of possibly less obstructive tissue valves [29,30,63] and left ventricular-aortic.conduits [66].
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135, March 1878
Surgeons are presently able to choose from a variety of satisfactory valve prostheses, depending on the individual situation. The durability, thromboembolic potential, and hemodynamic properties of any valve must be balanced against specific anatomic and clinical factors. Thus, if a surgeon is most concerned about durability, he might choose the bare strut Starr-Edwards ball valve or the Smeloff-Cutter valve, the most proven valves by length of service. However, the Bjork-Shiley, Lillehei-Kaster, and Hancock valves all have good durability records to seven years. Thromboembolic potential is markedly decreased with tissue valves such as the Hancock porcine xenograft, Carpentier-Edwards porcine xenograft, Ionescu-Shiley pericardial valve, or dura mater valve. Patients with these valves do not usually require chronic anticoagulation, which is associated with significant morbidity and mortality. In clinical situations that contraindicate long-term anticoagulation or when the threat of thromboembolism or bleeding is very high, the use of a tissue valve is particularly indicated. Hemodynamic considerations may be paramount in some patients with restrictive anatomy; the small diameter, tilting disc valves have the best hemodynamic performance, although new modifications in the Hancock porcine heterograft may reduce the hemodynamic obstruction in these small diameter valves and allow their implantation without longterm anticoagulation. A number of durable and effective devices exist today for valve replacement, and the type of valve used can be individualized according to the valve characteristics, clinical indications, and anatomic considerations.
449
Cohn
References 1. Cushing l-l, Branch JRB: Experimental and clinical notes on chronic valvular lesions in the dog and their possible relation to future surgery of the cardiac valves. J Med Res 7: 47 1, 1907. 2. Cutler EC, Levine SA: Cardiotomy and valvulotomy for mitral stenosis. Experimental observations and clinical notes concerning an operated case with recovery. Boston Med Surg J 188: 1023. 1923. 3. Harken DE, Ellis LB, Ware PF, Norman LR: The surgical treatment of mitral stenosis. I. Valvuloplasty. New Er@ J Med 239: 801.1948. 4. Harken DE, Soroff HS, Taylor WF, et al: Partial and complete prostheses in aortic insufficiency. J Thorac Cardiovasc Surg 40: 744, 1960. 5. Starr A, Edwards ML: Mitral replacement: clinical experience with a ball-valve prosthesis. Ann Surg 154: 726. 196 1. 6. Brunton L: Preliminary note on the possibility of treating mitral stenosis by surgical methods. Lancef 1: 352, 1902. 7. Editorial. Lancef 1: 461, 1902. 8. Allen DS. Graham EA: Intracardiac surgery: a new method. JAMA 79: 1028.1922. 9. Cutler EC, Levine SA, Beck CS: Surgical treatment of mitral stenosis: experimental and clinical studies. Arch Surg 9: 689, 1924. 10. Beck CS, Cutler EC: A cardiovalvulotome. J Exp Med 40: 375, 1924. 11. Souttar HS: The surgical treatment of mitral stenosis. Br Med J 2: 603, 1925. 12. Cutler EC, Beck CS: The present status of surgical procedures in chronic valvular disease of the heart: final report of all surgical cases. Arch Surg 18: 403, 1929. 12A. Bailey CP: The surgical treatment of mitral stenosis (commissurotomy). Dis Chest 15: 377. 1949. 13. Hufnagle CA, Harvey WP: The surgical correction of aortic regurgitation. Bull Georgetown Univ Med Center 6: 60, 1953. 14. Kay EB, Suzuki A, Demaney M, et al: Comparison of ball and disc valves for mitral valve replacement. Am J Cardioll8: 504, 1966. 15. Wada J: Knotless suture method and Wada Hingleless valve. Jpn J Thorac Surg 15: 88, 1967. 16. Murray G: Homologous aortic valve, segment transplants as surgical treatment for aortic and mitral insufficiency. Angioiogy 7: 446, 1956. 17. Kerwin AJ, Lenkei SC, Wilson DR: Aortic valve homograft in the treatment of aortic insufficiency. New Errg/ J Med 266: 852, 1962. 18. Barrett-Boyes BG: Homograft aortic valve replacement in aortic incompetence and stenosis. Thorax 19: 131, 1964. 19. Ross DN: Homograft replacement of the aortic valve. Lancet 2: 487, 1962. 20. Angel1 WW, Shumway NE, Kosek JC: Five-year study of viable aortic valve homografts. J Thorac Cardiovasc Surg 64: 329, 1972. 21. Barrett-Boyes BG. Roche AHG, Whitlock HML: Six-year review of results of freehand aortic valve replacement using an antibiotic sterilized homograft valve. Circulation 55: 353, 1977. 22. Wallace RB: Tissue valves. Am J Cardiol35: 866, 1975. 23. Binet JP, Carpentier A, Langlois J: Implantation de valves heterogenes dans le traitement des cardiopathies aortiques. CR Acad SC (Paris) 261: 5733, 1965. 24. O’Brien MF, Clarebrough JK: Heterograft aortic valve transplantation for human valve disease. Med J Aust 2: 228. 1966. 25. Buch S, Kosek JC, Angel1Ww: Deterioration of formalin-treated aortic heterografts. J Thorac Cardiovasc Surg 69: 673, 1970.
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26. Carpentier A, Lemaigre G, Robert L: Biological factors affecting long-term results of valvular heterografts. J Thorac Cardiovast Surg 58: 467, 1969. 27. Reis RL, Hancock WD. Yarbrough JW, et al: The flexible stent: a new concept in the fabrication of tissue heart valve prostheses. J Thorac Cardiovasc Surg 62: 683. 197 1. 28. Senning A: Fascia lata replacement of the aortic valve. J Thorac Cardiovasc Surg 54: 465. 1967. 29. Puig LB, Verginelli G, lryia K, et al: Homologous dura mater cardiac valves. J Thorac Cardiovasc Surg 69: 722, 1975. 30. lonescu MI, Tandon AP. Mary DAS, et al: Heart valve replacement with the lonescu-Shiiey pericardial xenograft. J Thorac Cardiovasc Surg73: 31, 1977. 37. Symposium: Evaluation of Results of Cardiac Surgery (Dexter L, ed). Circulation 37 (Suppl V), 1968. 32. Starr A, Pierie UR, Raible DA, et al: Cardiac valve replacement. Experience with the durability of silicone rubber. Circuiafion 33, 34 (Suppl I): 1, 1966. 33. Braunwald NS, Broncheck LI: Controlled tissue ingrowth in prosthetic cardiac valves. Rev Surg 23: 200, 1966. 34. Bonchek LI, Starr A: Ball valve prostheses: current appraisal of late results. Am J Cardiol35: 843, 1975. 35. Barnhorst DA, Oxman HA, Connolly DC: Isolated replacement of the aortic valve with the Starr-Edwards prosthesis: a 9year review. J Thorac Cardiovasc Surg 70: 113, 1975. 36. McHenry MM, Smeloff EA. Davey TB: Hemodynamic results with full-flow orifice prosthetic valves. Circulation 35, 36 (Suppl I): 24, 1967. 37. Davey TB, Smeloff EA: Development of a cardiac valve substitute: the Smeloff-Cutter prosthesis. Med lnstrum 11: 95, 1977. 38. Lee SJK, Barr C, Callaghan JC: Long-term survival after aortic valve replacement using Smeloff-Cutter prosthesis. Circulation 52: 113, 1975. 39. Bjork VO: A new tilting disc valve prosthesis. Stand J Thorac Cardiovasc Surg 3: 1, 1969. 40. Lillehei CW, Kaster RL, Block JH: Clinical experience with the new central flow pivoting disc aortic and mitral prosthesis. Chest 60: 290, 1971. 41. Bjork VO, Henze A, Holmgren A: Five years experience with the Bjork-Shiley tilting disc valve in isolated aortic valvular disease. J Thorac Cardiovasc Surg 68: 393, 1974. 42. Stalpaert G, Daenen W: Experience with the Bjork-Shiley prosthesis: 365 cases. (Unpublished data.) 43. Starek PJK, Mclaurin LP, Wilcox BR: Clinical evaluation of the Lillehei-Kaster pivoting disc valve. Ann Thomc Surg 22: 362, 1976. 44. Mitha AS, Matisonn RE, le Roux BT, et al: Clinical experience with the Lillehei-Kaster pivoting disc prosthesis. J Thorac Cardiovasc Surg 72: 401, 1976. 45. Stinson EB, Griepp RB, Oyer PE, et al: Long-term experience with porcine aortic valve xenografts. J Thorac Cardiovasc Surg 73: 54, 1977. 46. Cohn LH, Sanders JH Jr, Collins JJ Jr: Aortic valve replacement with the Hancock porcine xenograft. Ann Thorac Surg 22: 221, 1976. 47. Zuhdi N: Personal communication, 1977. 48. Fishbein MC, Gissen SA, Collins JJ, et al: Pathology of cardiac valve replacement with glufaraldehyde-fixed porcine valves. Am JCardiol40: 331, 1977. 49. Barnhorst DA, Oxman HA, Connolly DC, et al: Isolated replacement of the mitral valve with the Starr-Edwards prosthesis. J Thorac Cardiovasc Surg 71: 230, 1976. 50. Fishman NH, Edmunds LH, Hutchinson JC, et al: Five-year experience with the Smeloff-Cutter mitral prosthesis. J Thorac Cardiovasc Surg 62: 345, 1971. 51. Oxman HA, Connolly DC, Ellis FH: Mitral valve replacement with the Smeloff-Cutter prosthesis. J Tfwrac Cardiovasc Surg 69: 247,1975. 52. Beall AC, Morris GC, Howell JF, et al: Clinical experience with an improved mitral valve prosthesis. Ann Thorac Surg 15:
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601, 1973. 53. Salomon NW, Steele PP, Paton BC: Thromboembolism after Beall valve replacement of the mitral valve. Ann Thorax Surg 19: 33. 1975. 54. Lepley D, Flemma RJ, Muller DC, et al: Late evaluation of patients undergoing valve replacement with the Bjork-Shiley prosthesis. Ann Thorac Surg 24: 131, 1977. 55. Cohn LH, Sanders JJ Jr, Collins JJ Jr: Actuarial comparison of Hancock porcine and prosthetic disc valves for isolated mitral valve replacement. Circulation 54 (Suppl Ill): 60. 1976. 56. Clark RE, Grubbs FL, McKnight RC: Late clinical problems with Beall model 103 and 104 mitral valve prostheses: hemolysis and valve wear. Ann Thorac Surg 21: 475, 1976. 57. Hannah H, Reis RL: Current status of porcine heterograft prostheses. Circulation 54 (Suppl Ill): 27, 1976. 56. Levitsky S: In discussion of [ 451. 59. Byrd CL, Yahr WZ, Greenberg JJ: Long-term results of “simple” thrombectomy for thrombosed Bjork-Shiley aortic valve prostheses. Ann Thorac Surg 20: 265, 1975.
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60. Wright JTM, Brown MC: A method for measuring the mean pressure gradient across prosthetic heart valves under in vitro pulsatile flow conditions. A&d lnstfum 11: 110, 1977. 61. Roschke EJ, Harrison EC: Size comparisons of commercial prosthetic heart valves. Med Instrum 7: 277, 1973. 62. Jones EL, Craver JM, Hatcher CR: Clinical experience with the Hancock porcine xenograft valve. Am J Car&o/ 39: 303, 1977. 63. Wright JTM: A pulsatile flow study comparing the Hancock porcine xenograft aortic valve prostheses models 242 and 250. hkdlnstrum 11: 114, 1977. 64. Roberts WC: Choosing a substitute cardiac valve: type, size, surgeon. Am J Cardiol38: 633, 1976. 65. McIntosh CL, Michaelis LL, Morrow AG: Atrioventricular valve replacement with the Hancock porcine xenoqatt: a fife-year clinical experience. Surgery 76: 766, 1975. 66. Cooley DA, Norman JC, Mullins CE: Left ventricle to abdominal aorta conduit for relief of aortic stenosis. Bull Texas Heart lnst 2: 376. 1975.
451
Lawrence H. Cohn, MD, Boston, Massachusetts
A review of valvular heart surgery has relevance to Doctor J. Englebert Dunphy’s distinguished surgical career? As a student, house officer, and professor he was closely associated with surgeons who made significant advances in the treatment of valvular heart surgery. As a student at the Harvard Medical School he worked in the clinic of Doctor Harvey Cushing, Professor of Surgery at the Peter Bent Brigham Hospital, who performed some of the first experiments to produce and correct mitral stenosis [I]. As a resident in surgery at the Peter Bent Brigham Hospital, Doctor Dunphy worked with Doctor Elliot Cutler, who performed the first successful clinical mitral valve operation in 1923 [2]. As a member of the senior staff of the hospital, he worked with Doctor Dwight Harken, who performed one of the first series of closed mitral commissurotomies [3] and developed the concept of the ball and cage heart valve [4]. Finally, while Doctor Dunphy was Chairman of Surgery at the University of Oregon, Doctor Albert Starr developed and successfully implanted the first consistently reliable heart valve prosthesis [5]. Historic Review
Surgical treatment of diseased human heart valves was first discussed by Sir Lauder Brunton [6] in the Lancet in 1902. His observations on human cadavers indicated that mitral stenosis might be correctable by merely cutting the stenosed commissures with a
From the Department of Surgery, Division of Thoracic and Cardiac Surgery, Harvard Medical School, and Peter Bent Brigham Hospital, Boston, Massachusetts. Reprint requests should be addressed to Lawrence H. Cohn, MD, Department of Surgery, Peter Bent Brigham Hospital, 721 Huntington Avenue, Boston, Massachusetts 02115. Presented in part at the Sixty-Second American College of Surgeons Cardiovascular Surgical Postgraduate Course, 1976.
444
knife inserted via the chambers of the heart. Although his suggestion was rebuked in the next issue of the Lancet [7], it stimulated interest in the pathophysiology and surgical treatment of valvular heart disease. During 1902 to 1923 a number of surgical investigators, including Cushing and Branch [1] and Allen and Graham [a], performed experiments to surgically create and correct mitral stenosis. Cutler, Levine, and Beck [9] also performed basic cardiac surgical experiments to determine the amount of operative trauma that the heart could withstand. Cutler and Levine [2] by 1923 had formulated their concept of the pathology of mitral stenosis, concluding that there was a mechanical obstruction that could be corrected by excision of a segment from the valve; therefore, Beck and Cutler [IO] developed a special instrument, the cardiovalvulotome. (Figure 1.) They believed that the congestive failure associated with mitral stenosis was due to the mechanical obstruction of the valve rather than myocardial disease, the commonly held theory of the time, Cutler and Levine in May 1923 operated on their first patient, a twelve year old girl dying of mitral stenosis. After median sternotomy, Doctor Cutler inserted a tenotomy knife (his cardiovalvulotome had not yet arrived) through the apex of the left ventricle and bindly cut both mitral commissures. The patient survived, recovered, and lived for four and a half years [2]. Cutler performed six additional operations in the 192Os, using his cardiovalvulotome; all six patients died in the immediate postoperative period from massive mitral regurgitation. In 1925, two years after Cutler’s first operation, an important operation was performed by Henry Souttar [II] at the London Hospital (ironically, the hospital of Sir Brunton): he inserted his index finger through the atria1 appendage to enlarge the opening in the mitral valve. Despite the suc-
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cessful outcome, he received no further patients. Cutler and Beck [12] in 1929 reviewed all twelve patients with cardiac valvular disease operated on to that time and suggested a moratorium because of the high mortality. The amount of valve tissue removed with the cardiovalvulotome had created deleterious mitral regurgitation. However, they prophetically suggested that Souttar’s finger fracture technic might eventually prove to be the best. In 1948, Harken et al [3] began performing mitral valvuloplasties at the Peter Bent Brigham Hospital, utilizing the left atria1 approach. At the same time, Charles Bailey [12A] of Philadelphia began his series of closed mitral operations. These surgeons began the “modern” era of cardiac surgery, and from 1948 to date there has been continuous modification and improvement in the treatment of valvular heart disease. After the development of the heart-lung machine in 1953 by Gibbon, surgeons debrided calcific aortic valves and inserted a small number of artificial leaflet valves or implanted Hufnagle’s ball and cage valve in the descending aorta for partial correction of aortic regurgitation [13]. These operations were only moderately successful and for only a small number of carefully selected patients. The first artificial ball and cage aortic valve for the subcoronary position was conceived, fabricated, and implanted by Harken et al [4] in 1959. The first series of successful aortic and mitral valve prosthetic replacements was accomplished by Starr and Edwards [5] in 1960 using the Starr-Edwards ball and cage valve. This achievement opened the way for effective treatment of large numbers of patients with severe valvular heart disease with a hemodynamically safe and durable prosthetic device. Subsequently, low profile disc and cage valves [14] and tilting disc central flow valves [15] were developed with improved hemodynamics. Concurrent with the development of prosthetic heart valves, homograft tissue heart valves were developed because of their decreased proclivity to thromboemboli. In 1956, Murray [16] placed fresh homograft aortic valves in the descending thoracic aorta, which were found to be still functioning normally seven years later [ 171. In 1960, Barrett-Boyes [18] and Ross [19] began performing subcoronary aortic valve replacement with free sewn homografts. However, the valves, prepared and sterilized by a variety of chemicals, lacked durability, causing high reoperation rates. Fresh, antibiotic-treated homografts [20,21] or frozen, irradiated valves [22] were more durable, but the late failure rates led to the discontinuation of homograft valve replacement except in special situations. In 1965, after experi-
Volume 135, March 1370
mental work by Binet, Carpentier, and Langlois [23], porcine heterograft valves were sterilized with formaldehyde and sewn on stents for clinical valve replacement [24]; however, frequent early graft failure from collagen disruption made this form of preservation unacceptable [25]. In 1968, Carpentier, Lemaigre, and Robert [26] fixed and sterilized porcine heart valves in glutaraldehyde and documented satisfactory six year durability. In 1969 Reis et al [27] fabricated a semiflexible valve stent upon which porcine heterografts treated with a special glutaraldehyde process were sewn. The Hancock valve, now widely used, became the first quality-controlled, mass-produced tissue valve. Other forms of biologic material utilized for fabrication of cardiac valves have included fascia lata [28], homologous dura mater [29], and heterologous glutaraldehyde-fixed pericardium [30]. The last two of these have been successfully used by their originators for more than five years with excellent durability, low incidence of thromboembolism, and satisfactory hemodynamic performance. Evaluation of Cardiac Valve Devices
If surgery results in satisfactory hemodynamic performance, it is preferable to preserve and reconstruct the patient’s own valve whenever possible because the ideal replacement valve has not yet been developed. Since the development sixteen years ago of the first reliable device for valve replacement, one fact has emerged: for patients with severe valvular heart lesions, long-term survival after aortic, mitral, or multiple valve replacement is superior to that after medical treatment [31]. Following is an evaluation of the durability, thromboembolic potential, and hemodynamic per-
Figure 1. The cardiovalvulotome circa 1923.
of Doctor Elliot Cut/er,
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formance of the ball and cage valve, tilting disc, and glutaraldehyde-treated porcine xenograft. Durabllity
Aortic Values. (Table I). Of all heart valves presently in use, the Starr-Edwards bare strut ball valve model 1260, developed in 1965 after the first StarrEdwards valve demonstrated silicone ball variance from cholesterol absorption [32], has the longest continuous durability record. The cloth-covered Starr-Edwards valve was introduced in 1967 to reduce the incidence of thromboembolism, because experimental data [33] suggested that the struts might become endothelialized. This valve, however, introduced new durability problems from cloth wear and hemolysis, requiring several model changes; the incidence of reoperations for these complications was estimated at 10 per cent at five years [34,35]. The Smeloff-Cutter full orifice bare strut ball and cage valve [36], developed in 1966, had a slightly better hemodynamic performance than the StarrEdwards valve. It has been used for ten years and has an excellent durability record [37,38] and no ball variance. In 1969 the low profile semicentral flow disc valves were introduced to improve the effective orifice area and relieve obstruction at secondary and tertiary outflow areas (39,401. The Bjork-Shiley tilting disc valve now employs a pyrolite-occluding disc, after initially using a delrin disc which was discontinued
TABLE I
because of fatigue problems [41,42]. The LilleheiKaster tilting disc valve, although similar in design, has a theoretical hemodynamic advantage because the disc occluder opens to a more central position. Durability of these aortic valves has been uniformly good, with no reported cases of valve dysfunction [43,44]. The Hancock glutaraldehyde-stabilized porcine heterograft valve has been reliable in the aortic position since 1970, and actuarial survival data have been equal to those of artificial prosthetic valves [45-471. A recent postoperative pathologic examination of Hancock aortic valves by Fishbein et al [48] indicated that in the absence of infection, collagen durability is satisfactory to 6 years. They observed only one abnormal aortic valve in a patient on chronic dialysis who developed microscopic valvular calcification. Mitral Values. Table II summarizes actuarial survival data on the following mitral prostheses currently in use: Starr-Edwards valve [34,49], Smeloff-Cutter valve [50,51], Beall disc and cage [52,53], Bjork-Shiley valve [42,54], Lillehei-Kaster valve [43,44], and Hancock porcine xenograft [45,47,55]. Strut cloth wear of the Starr-Edwards valve, a significant problem in the aortic position, has not occurred with the mitral prosthesis. Acceptable durability and patient survival have been achieved with the Hancock porcine valve; a 0.1 per cent incidence of primary valvular dysfunction has occurred with
Aortic Valve Replacement Devices
Valve S-E 1260 2310 2400 S-E 1260 S-C S-C B-S B-S L-K L-K Hancock Hancock
Authors Bonchek and Starr [34] Barnhorst et al [ 351 Davey and Smeloff [ 371 Lee, Barr, and Callaghan [ 381 Stalpaert and Daenen [ 421 Bjork. Henze, and Holmgren [ 4 I] Starek, McLaurin, and Wilcox [ 431 Mitha et al [ 441 Stinson et al [ 451 Cohn, Sanders, and Collins [46]
No. of Patients
Years FU
(%)
Emboli1100 Patient-Years
132 116 132 962 160 187
9 6 2.5 0 10 8
72’ 80’ 73’ 65’ 90’ 60
4.2 0 anticoagI8.8no a/c 6.1 3.5 1.0+ 3.6
140
5
90
0.7+
160
5
86
1.5
61
5
95
0
3 4 3.5
a2 91 04
6.0 2.1 1.0
49 167 71
Survival
Note: Representative clinical series of 5 most popular aortic valves prostheses. S-E = Starr-Edwards; S-C = Smeloff-Cutter; B-S = Bjork-Shiley; L-K = Lillehei-Kaster. Operative mortality omitted. + Estimate. l
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approximately 30,000 such valves in clinical use. In our own experience with 250 Hancock mitral valves, there has been one primary tissue failure due to a torn leaflet from the strut of the flexible stent in a mitral valve in place for eighteen months [48]. Hannah and Reis [57] and Levitsky [58] have documented a total of five cases of primary tissue fatigue. lhromboembolism
Despite improvements in valve durability, thromboembolism continues to be a significant problem, particularly in patients with replacement of the mitral valve. Warfarin anticoagulation, which has an estimated yearly morbidity and mortality of 1 per cent, has been necessary for all patients with prosthetic valves. The incidence of thromboembolic complications is expressed as the number of thromboemboli per 100 patient-years of follow-up. Aortic Values. Thrombolic complications with ball valves, tilting disc valves, and porcine bioprosthetic valves are indicated in Table I. The addition of a cloth covering to the Starr-Edwards valve decreased the incidence of thromboembolism; however, patients with these valves still require long-term anticoagulation [34]. Even though tilting disc valves have had a low incidence of thromboembolism, totally thrombosed Bjork-Shiley and Lillehei-Kaster aortic valves have been reported [46,59]. Discontinuation
TABLE II
Mitral
or change in the regimen of chronic anticoagulation seems to precipitate this event, and thrombectomy is the treatment of choice [59]. Patients with porcine aortic valves have not undergone anticoagulation and their rate of thromboembolism is low, typical of tissue valves in the aortic position. In the Brigham series of 152 Hancock aortic valve replacements, one seventy year old patient in chronic atria1 fibrillation had a nonfatal embolus and one eighty year old man who was taking estrogens for prostatic carcinoma had fatal thrombotic stenosis [46]. Mitral Values. Table II shows the thromboembolic rate for the ball and cage valve, disc and cage, tilting disc, and porcine valve. The ball and cage valve with cloth-covered struts produces emboli less often than the bare strut ball valve, but it still requires anticoagulation. Nonfatal emboli are uncommon with the tilting disc valve, but the rate of total thrombosis has been relatively high. The 10 per cent reported incidence of massive thrombosis of the Lillehei-Kaster valve [43,44] was perhaps due to insertion of too large a prosthesis. Mitral bioprosthetic valves have the lowest incidence of thromboemboli even when most patients do not undergo long-term anticoagulation. It is important, however, to emphasize that in patients with an enlarged left atrium and chronic atria1 fibrillation, particularly those with preoperative mitral regurgitation, the incidence of thromboemboli after tissue valve replacement is similar to that of
Valve Replacement Devices
Valve S-E 6120 6310 6400 S-E 6120 s-c s-c Beall Beall B-S B-S L-K L-K Hancock Hancock
No. of Patients
Authors Bonchek and Starr [34] Barnhorst et al [ 491 Fishman et al [ 501 Oxman, Connolly, and Ellis [ 5 I] Beall et al [ 52] Salomon, Steele, and Paton [ 531 Stalpaert and Daenen Lepley et al [ 541 Mitha et al [ 441 Starek, McLaurin, and Wilcox [ 431 Stinson et al [45] Cohn, Sanders, and Collins [ 551
[ 421
Years Followed
Survival (%)
Emboli/lOO Patient-Years
64 171 90 311 132 79
9 5 2 6 5 6
75’ 80’ 89’ 80’ 60 70
6.0 1.5 8.8 7.4 8.0 6.1
100 76
2 5
87 89
4.0 1.1’
117 242 75 59
5 5 4 4
78 89’ 78 86
1.o+ 1.5 7+
244 56
4.5 4
85 94
5.3 1.6
6.7
Note: Representative clinical series of the commonly used mitral prosthetic and bioprosthetic valves. S-E = Starr-Edwards: S-C = Smeloff-Cutter; B-S = Bjork-Shiley; L-K = Lillehei-Kaster. Operative mortality omitted. + Estimate. l
Volums 135, March 1978
447
Cohn
cs 24
j
0
6
12
18
MONTHS
c 48
II
36
36
AFTER
42
I
1
54
60
66
patients with artificial prosthetic valves [55]. Under these circumstances, long-term anticoagulation should be used regardless of the type of valve employed: the emboli are a consequence of the cardiac lesion rather than the type of valvular prosthesis. In our experience with the Harken disc valve and the Hancock porcine heterograft (Figure 2), patients who maintained a sinus rhythm postoperatively had a significantly lower incidence of thromboembolism if they had a porcine valve (no anticoagulants). If patients were in chronic atria1 fibrillation postoperatively, there was no difference between the Hancock and Harken valves in the incidence of thromboembolism over the four year follow-up period [55].
OPERATION
Figure 2A. Overall incidence of emboii in patients undergoing mitral valve replacement wifh porcine or disc valve.
Hemodynamics
All prosthetic and bioprosthetic valves produce varying degrees of hemodynamic obstruction, depending upon the size of the annulus diameter, the patient’s cardiac output, and the effective orifice area of the valve. A considerable amount of hemodynamic data have been accumulated from patients with ball, tilting disc, and tissue valves; over a wide range of diameters, they are generally nonobstructive, except when the annulus is small. In vitro studies of aortic and atrioventricular valves have shown that most valves are effective in relieving hemodynamic obstructions over a wide range of heart rates and flows
W’l.
65 f f 0
I,,
6
12
16
*
24
MONTHS
*
30
I1
1..
36
42
AFTER
48
,
64
60
66
OPERATION
Figure 28. Incidence of emboli in patients wifh postoperafive sinus rhythm after porcine or disc mitral valve re-
Aortic Valves. A small aortic annulus may produce hemodynamic obstruction with some heart valves. In addition, when the aortic root is small, hemodynamic obstruction may occur at the secondary and tertiary orifices above the aortic annulus. These areas may become obstructed with high profile valves, such as ball and cage valves, unless the aorta is patched with a prosthetic gussett. The Bjork-Shiley and Lillehei-Kaster central flow valves have the lowest transvalvular gradients and the largest effective orifice areas at any annulus diameter and are currently favored by many surgeons when a small annulus is encountered. This can be
TABLE III
Prosthetic Aortic Valves
a@ 85.
0
-
6
12
18
24
MONTHS
30 AFTER
36
42
48
64
60
66
OPERATION
Figure 2C. Incidence of emboii in patients with postoperative chronic afriai fibrillation after porcine or disc valve repiacemenf. (Figures 2A, B, and C reproduced wifh permission from the American Heart Association from [ 551,
44%
Valve
Size
Annulus Diameter (mm)
Bjork-Shiley Lillehei-Kaster Starr-Edwards Smeloff-Cutter Starr-Edwards
19 l4A 8A A2 9A
19 21 21 21 23
0 DISC & (11.27)
Note: Abstracted from
Effective Orifice Area (cm? 1.50 1.50 1.41 1.54 1.70
[ 6 I].
The American Journal of Surgery
Valvular Heart Disease
F/gure 3. Modified orifice Hancock aotiic valve and standard model Hancock aotiic valve (ieft hand). Free-sewn leaflet replaces septai muscle bar of right coronary leaflet a//owing complete mobiiity with systo/e.
Summary
appreciated by comparing diameters of various prosthetic valves in Table III (abstracted from Roschke and Harrison [61]). Hannah and Reis [58], Jones, Craver, and Hatcher [62], and Cohn, Sanders, and Collins [46] documented significant transvalvular gradients in the 21 and 23 mm sizes of the conventional Hancock aortic valve. The gradients are due to the immobile right ventricular muscle on the inferior aspect of the right coronary leaflet. Thus, the smaller the valve, the more obstruction caused by this fixed segment. Recently, Hancock Laboratories modified the aortic valve by removing the muscular cusp and inserting a free-sewn nonmuscular cusp from another porcine aortic valve into the stent. This arrangement has the effect of allowing all three cusps to open completely during systole, thus obviating hemodynamic obstruction [63]. (Figure 3.) Mitral Valves. Hemodynamic obstruction of prosthetic mitral valves is uncommon in adults unless: (1)thrombotic obstruction occurs; (2) there is annular dysproportion (a large individual with a high cardiac output and a congenitally small tissue annulus); or (3) too large a valve is placed in a patient with a small left ventricular cavity [64], a factor which may be responsible for valve thromboses. The Hancock porcine mitral valve behaves in a similar fashion hemodynamically at rest and exercise as the artificial prosthetic valve of the same size [57,65]. In children with endocardial cushion defects or aortic valve endocarditis, hemodynamic obstruction by an artificial or tissue valve may be significant. This has stimulated fabrication of possibly less obstructive tissue valves [29,30,63] and left ventricular-aortic.conduits [66].
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135, March 1878
Surgeons are presently able to choose from a variety of satisfactory valve prostheses, depending on the individual situation. The durability, thromboembolic potential, and hemodynamic properties of any valve must be balanced against specific anatomic and clinical factors. Thus, if a surgeon is most concerned about durability, he might choose the bare strut Starr-Edwards ball valve or the Smeloff-Cutter valve, the most proven valves by length of service. However, the Bjork-Shiley, Lillehei-Kaster, and Hancock valves all have good durability records to seven years. Thromboembolic potential is markedly decreased with tissue valves such as the Hancock porcine xenograft, Carpentier-Edwards porcine xenograft, Ionescu-Shiley pericardial valve, or dura mater valve. Patients with these valves do not usually require chronic anticoagulation, which is associated with significant morbidity and mortality. In clinical situations that contraindicate long-term anticoagulation or when the threat of thromboembolism or bleeding is very high, the use of a tissue valve is particularly indicated. Hemodynamic considerations may be paramount in some patients with restrictive anatomy; the small diameter, tilting disc valves have the best hemodynamic performance, although new modifications in the Hancock porcine heterograft may reduce the hemodynamic obstruction in these small diameter valves and allow their implantation without longterm anticoagulation. A number of durable and effective devices exist today for valve replacement, and the type of valve used can be individualized according to the valve characteristics, clinical indications, and anatomic considerations.
449
Cohn
References 1. Cushing l-l, Branch JRB: Experimental and clinical notes on chronic valvular lesions in the dog and their possible relation to future surgery of the cardiac valves. J Med Res 7: 47 1, 1907. 2. Cutler EC, Levine SA: Cardiotomy and valvulotomy for mitral stenosis. Experimental observations and clinical notes concerning an operated case with recovery. Boston Med Surg J 188: 1023. 1923. 3. Harken DE, Ellis LB, Ware PF, Norman LR: The surgical treatment of mitral stenosis. I. Valvuloplasty. New Er@ J Med 239: 801.1948. 4. Harken DE, Soroff HS, Taylor WF, et al: Partial and complete prostheses in aortic insufficiency. J Thorac Cardiovasc Surg 40: 744, 1960. 5. Starr A, Edwards ML: Mitral replacement: clinical experience with a ball-valve prosthesis. Ann Surg 154: 726. 196 1. 6. Brunton L: Preliminary note on the possibility of treating mitral stenosis by surgical methods. Lancef 1: 352, 1902. 7. Editorial. Lancef 1: 461, 1902. 8. Allen DS. Graham EA: Intracardiac surgery: a new method. JAMA 79: 1028.1922. 9. Cutler EC, Levine SA, Beck CS: Surgical treatment of mitral stenosis: experimental and clinical studies. Arch Surg 9: 689, 1924. 10. Beck CS, Cutler EC: A cardiovalvulotome. J Exp Med 40: 375, 1924. 11. Souttar HS: The surgical treatment of mitral stenosis. Br Med J 2: 603, 1925. 12. Cutler EC, Beck CS: The present status of surgical procedures in chronic valvular disease of the heart: final report of all surgical cases. Arch Surg 18: 403, 1929. 12A. Bailey CP: The surgical treatment of mitral stenosis (commissurotomy). Dis Chest 15: 377. 1949. 13. Hufnagle CA, Harvey WP: The surgical correction of aortic regurgitation. Bull Georgetown Univ Med Center 6: 60, 1953. 14. Kay EB, Suzuki A, Demaney M, et al: Comparison of ball and disc valves for mitral valve replacement. Am J Cardioll8: 504, 1966. 15. Wada J: Knotless suture method and Wada Hingleless valve. Jpn J Thorac Surg 15: 88, 1967. 16. Murray G: Homologous aortic valve, segment transplants as surgical treatment for aortic and mitral insufficiency. Angioiogy 7: 446, 1956. 17. Kerwin AJ, Lenkei SC, Wilson DR: Aortic valve homograft in the treatment of aortic insufficiency. New Errg/ J Med 266: 852, 1962. 18. Barrett-Boyes BG: Homograft aortic valve replacement in aortic incompetence and stenosis. Thorax 19: 131, 1964. 19. Ross DN: Homograft replacement of the aortic valve. Lancet 2: 487, 1962. 20. Angel1 WW, Shumway NE, Kosek JC: Five-year study of viable aortic valve homografts. J Thorac Cardiovasc Surg 64: 329, 1972. 21. Barrett-Boyes BG. Roche AHG, Whitlock HML: Six-year review of results of freehand aortic valve replacement using an antibiotic sterilized homograft valve. Circulation 55: 353, 1977. 22. Wallace RB: Tissue valves. Am J Cardiol35: 866, 1975. 23. Binet JP, Carpentier A, Langlois J: Implantation de valves heterogenes dans le traitement des cardiopathies aortiques. CR Acad SC (Paris) 261: 5733, 1965. 24. O’Brien MF, Clarebrough JK: Heterograft aortic valve transplantation for human valve disease. Med J Aust 2: 228. 1966. 25. Buch S, Kosek JC, Angel1Ww: Deterioration of formalin-treated aortic heterografts. J Thorac Cardiovasc Surg 69: 673, 1970.
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26. Carpentier A, Lemaigre G, Robert L: Biological factors affecting long-term results of valvular heterografts. J Thorac Cardiovast Surg 58: 467, 1969. 27. Reis RL, Hancock WD. Yarbrough JW, et al: The flexible stent: a new concept in the fabrication of tissue heart valve prostheses. J Thorac Cardiovasc Surg 62: 683. 197 1. 28. Senning A: Fascia lata replacement of the aortic valve. J Thorac Cardiovasc Surg 54: 465. 1967. 29. Puig LB, Verginelli G, lryia K, et al: Homologous dura mater cardiac valves. J Thorac Cardiovasc Surg 69: 722, 1975. 30. lonescu MI, Tandon AP. Mary DAS, et al: Heart valve replacement with the lonescu-Shiiey pericardial xenograft. J Thorac Cardiovasc Surg73: 31, 1977. 37. Symposium: Evaluation of Results of Cardiac Surgery (Dexter L, ed). Circulation 37 (Suppl V), 1968. 32. Starr A, Pierie UR, Raible DA, et al: Cardiac valve replacement. Experience with the durability of silicone rubber. Circuiafion 33, 34 (Suppl I): 1, 1966. 33. Braunwald NS, Broncheck LI: Controlled tissue ingrowth in prosthetic cardiac valves. Rev Surg 23: 200, 1966. 34. Bonchek LI, Starr A: Ball valve prostheses: current appraisal of late results. Am J Cardiol35: 843, 1975. 35. Barnhorst DA, Oxman HA, Connolly DC: Isolated replacement of the aortic valve with the Starr-Edwards prosthesis: a 9year review. J Thorac Cardiovasc Surg 70: 113, 1975. 36. McHenry MM, Smeloff EA. Davey TB: Hemodynamic results with full-flow orifice prosthetic valves. Circulation 35, 36 (Suppl I): 24, 1967. 37. Davey TB, Smeloff EA: Development of a cardiac valve substitute: the Smeloff-Cutter prosthesis. Med lnstrum 11: 95, 1977. 38. Lee SJK, Barr C, Callaghan JC: Long-term survival after aortic valve replacement using Smeloff-Cutter prosthesis. Circulation 52: 113, 1975. 39. Bjork VO: A new tilting disc valve prosthesis. Stand J Thorac Cardiovasc Surg 3: 1, 1969. 40. Lillehei CW, Kaster RL, Block JH: Clinical experience with the new central flow pivoting disc aortic and mitral prosthesis. Chest 60: 290, 1971. 41. Bjork VO, Henze A, Holmgren A: Five years experience with the Bjork-Shiley tilting disc valve in isolated aortic valvular disease. J Thorac Cardiovasc Surg 68: 393, 1974. 42. Stalpaert G, Daenen W: Experience with the Bjork-Shiley prosthesis: 365 cases. (Unpublished data.) 43. Starek PJK, Mclaurin LP, Wilcox BR: Clinical evaluation of the Lillehei-Kaster pivoting disc valve. Ann Thomc Surg 22: 362, 1976. 44. Mitha AS, Matisonn RE, le Roux BT, et al: Clinical experience with the Lillehei-Kaster pivoting disc prosthesis. J Thorac Cardiovasc Surg 72: 401, 1976. 45. Stinson EB, Griepp RB, Oyer PE, et al: Long-term experience with porcine aortic valve xenografts. J Thorac Cardiovasc Surg 73: 54, 1977. 46. Cohn LH, Sanders JH Jr, Collins JJ Jr: Aortic valve replacement with the Hancock porcine xenograft. Ann Thorac Surg 22: 221, 1976. 47. Zuhdi N: Personal communication, 1977. 48. Fishbein MC, Gissen SA, Collins JJ, et al: Pathology of cardiac valve replacement with glufaraldehyde-fixed porcine valves. Am JCardiol40: 331, 1977. 49. Barnhorst DA, Oxman HA, Connolly DC, et al: Isolated replacement of the mitral valve with the Starr-Edwards prosthesis. J Thorac Cardiovasc Surg 71: 230, 1976. 50. Fishman NH, Edmunds LH, Hutchinson JC, et al: Five-year experience with the Smeloff-Cutter mitral prosthesis. J Thorac Cardiovasc Surg 62: 345, 1971. 51. Oxman HA, Connolly DC, Ellis FH: Mitral valve replacement with the Smeloff-Cutter prosthesis. J Tfwrac Cardiovasc Surg 69: 247,1975. 52. Beall AC, Morris GC, Howell JF, et al: Clinical experience with an improved mitral valve prosthesis. Ann Thorac Surg 15:
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601, 1973. 53. Salomon NW, Steele PP, Paton BC: Thromboembolism after Beall valve replacement of the mitral valve. Ann Thorax Surg 19: 33. 1975. 54. Lepley D, Flemma RJ, Muller DC, et al: Late evaluation of patients undergoing valve replacement with the Bjork-Shiley prosthesis. Ann Thorac Surg 24: 131, 1977. 55. Cohn LH, Sanders JJ Jr, Collins JJ Jr: Actuarial comparison of Hancock porcine and prosthetic disc valves for isolated mitral valve replacement. Circulation 54 (Suppl Ill): 60. 1976. 56. Clark RE, Grubbs FL, McKnight RC: Late clinical problems with Beall model 103 and 104 mitral valve prostheses: hemolysis and valve wear. Ann Thorac Surg 21: 475, 1976. 57. Hannah H, Reis RL: Current status of porcine heterograft prostheses. Circulation 54 (Suppl Ill): 27, 1976. 56. Levitsky S: In discussion of [ 451. 59. Byrd CL, Yahr WZ, Greenberg JJ: Long-term results of “simple” thrombectomy for thrombosed Bjork-Shiley aortic valve prostheses. Ann Thorac Surg 20: 265, 1975.
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60. Wright JTM, Brown MC: A method for measuring the mean pressure gradient across prosthetic heart valves under in vitro pulsatile flow conditions. A&d lnstfum 11: 110, 1977. 61. Roschke EJ, Harrison EC: Size comparisons of commercial prosthetic heart valves. Med Instrum 7: 277, 1973. 62. Jones EL, Craver JM, Hatcher CR: Clinical experience with the Hancock porcine xenograft valve. Am J Car&o/ 39: 303, 1977. 63. Wright JTM: A pulsatile flow study comparing the Hancock porcine xenograft aortic valve prostheses models 242 and 250. hkdlnstrum 11: 114, 1977. 64. Roberts WC: Choosing a substitute cardiac valve: type, size, surgeon. Am J Cardiol38: 633, 1976. 65. McIntosh CL, Michaelis LL, Morrow AG: Atrioventricular valve replacement with the Hancock porcine xenoqatt: a fife-year clinical experience. Surgery 76: 766, 1975. 66. Cooley DA, Norman JC, Mullins CE: Left ventricle to abdominal aorta conduit for relief of aortic stenosis. Bull Texas Heart lnst 2: 376. 1975.
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