Comparative analysis of isolated aortic valve replacement with fascia lata and homograft valves

Comparative analysis of isolated aortic valve replacement with fascia lata and homograft valves Thirty-eight consecutive patients who underwent isolated replacement of the aortic valve with fascia lata in 1970 were compared with a similar series of patients undergoing homograft replacement of the aortic valve. These series were well matched in numbers, age. sex of patients, symptomatology, valvular disease, electrocardiographic and roentegenographic changes, and preoperative cardiac catheterization data. The mean follow-up time was 73 months in the fascia lata series and 69.1 months in the homograft series, and all the post-operative survivors were reviewed. The early and long-term results were similar in the two series, and there was no statistical difference in the operative and late mortality, the incidence of early and late diastolic murmurs, valve failure necessitating valve replacement, infective endocarditis, thromboembolism, over-all survival, and survival with an intact valve. It is concluded that the long-term results of valve replacement using these two tissues, in the aortic position, are similar and there is little to choose between the two types of valves. If fascia lata, as we believe, is no longer acceptable as a satisfactory valve substitute, then homograft valves are not acceptable either.

Ajaib S. Soorae, M . B . , B.S., F.R.C.S. (Edin.), F.R.C.S. (Eng.), Hugh O'Kane, B . S c , F.R.C.S., M.Ch., Patrick J. Molloy, F.R.C.S., and Jack Cleland, M . B . , F.R.C.S., Belfast, Northern Ireland

V alve replacement is accepted as a logical treatment for the grossly diseased aortic valve in patients with a significant functional disability or hemodynamic abnormality. The choice of a suitable prosthesis varies between two main groups, tissue valves and prosthetic valves. The greatest advantage of tissue heart valves over prosthetic devices is that, with their use, the incidence of thromboembolism is minimal. Because longterm use of anticoagulants is not necessary, these valves have become more acceptable to many surgeons. Tissue valves, however, are subject to early and late failure owing to tissue degeneration or infection. Hence there has been a continuing search for a suitable tissue that will be free from these problems. GlutarFrom the Cardiac Surgical Unit, Royal Victoria Hospital, Grosvenor Road, Belfast, BTI2 6BA, Northern Ireland. Read at the Annual Meeting of The Society of Thoracic and Cardiovascular Surgeons of Great Britain and Ireland, London, October 13 and 14, 1977. Received for publication Feb. 24, 1978. Accepted for publication March 13, 1978. Address for reprints: Jack Cleland, M.B., F.R.C.S., Cardiac Surgical Unit, Royal Victoria Hospital, Grosvenor Road, Belfast, BT12 6BA, N. Ireland. 46

aldehyde-preserved heterograft valves are gaining widespread acceptance at present; however, for a period of time, homograft and fascia lata valves were also widely used as a replacement for the aortic valve. It is of interest, therefore, to review the early and longterm results with these two tissues inserted in the aortic position by one cardiac surgical team and followed up for a prolonged period of time. Patients and methods A total of 38 consecutive patients underwent isolated aortic valve replacement with fascia lata valves in 1970. No case selection was made, and the series comprises all the patients in whom fascia lata was used for aortic valve replacement in this unit. After 1970, the use of this valve in the aortic postion was discontinued because of early valve failure, especially in the mitral and tricuspid positions. Homograft valves were the first choice for aortic valve replacement when the Cardiac Surgical Unit at Royal Victoria Hospital was first established in June, 1968. However, the decision to use homografts also depended upon several factors: An adequate-sized valve had to be available, the patient had to be 0022-5223/78/0176-0046$01.00/0 © 1978 The C. V. Mosby Co.

Volume 76 Number 1 July, 1978

Aortic valve replacement

Table I. Preoperative patient data

Table II. Age distribution by decades Type of valve

Type of valve

No. of patients Age (yr.) Mean Range Sex Male Female Follow-up (mo.) Mean Range Symptoms Dyspnea Angina Syncope Functional disability* Class I Class II Class III Class IV Pathology Aortic stenosis Aortic incompetence Mixed ECG LVH LVH and strain Atrial fibrillation History Rheumatic fever Infective endocarditis Congenital defect

47

Fascia lata

Homograft

38

38

45.5 16-65

44 19-65

21 17

18 20

73 3-82

69 3-100

36 19 6

37 20 6

2 14 20 2

1 16 19 2

12 18 8

13 14 11

38 25 1

38 23 3

20 5 3

21 1 1

Legend: ECG, Electrocardiogram. LVH, Left ventricular hypertrophy. *New York Heart Association functional classes.

comparatively young, only a single valve had to be replaced, and long-term anticoagulation had to be relatively contraindicated. The first 38 patients in a consecutive series who had homograft replacement of the aortic valve were selected for comparison with the fascia lata series, and the results were analyzed in January, 1977. No attempt was made to match the two series. The patients who were selected for operation had either advanced functional disability or severe nemodynamic abnormality as shown by cardiac catheterization. No patient was turned down for operation because of advanced cardiac disease. The preoperative and postoperative data were collected from the patients' case notes, and the follow-up was complete in all the patients. These retrospective series were similar in number of patients (38), age, sex ratio, symptomatology, New York Heart Association functional class, electrocar-

Age (yr.)

Fascia lata (n = 38)

Homograft (n = 38)

11-20 21-30 31-40 41-50 51-60 61-70

2 3 8 13 10 2

2 3 8 10 12 3

Table III. Preoperative cardiothoracic ratio Type of valve

Cardiothoracic ratio Less than 50% 50 - 55% 56 - 60% More than 60% Range

Fascia lata (n = 38)

Homograft
10 14 8 6 43 - 71%

9 13 9 7 42 - 70%

diographic changes, and valvular disease (Table I). The mean follow-up was 73 months in the fascia lata series and 69.1 months in the homograft series, and the ranges were similar in the two series. The distribution of patients was evenly divided in each decade in both series, most of the patients being in the fifth and sixth decades (Table II). The cardiothoracic ratio was determined by measurement of the greatest transverse diameter of the heart and the internal diameter of the chest on a posteroanterior chest roentgenogram at the level of the diaphragm. The patients were divided into four groups for analysis according to the cardiothoracic ratio: less than 50 percent, 51 to 55 percent, 56 to 60 percent, and greater than 60 percent. The number of patients in each group and the range of cardiothoracic ratio were similar in the two series (Table III). Preoperative cardiac catheterization was carried out in all the patients. The peak systolic gradient across the aortic valve was measured, and the patients were divided into three main groups: those with dominant aortic stenosis, those with dominant aortic incompetence, and those with a mixture of stenosis and incompetence. The mean gradients were similar in each group of patients in both series (Table IV). Aortic regurgitation on angiography was graded as none, mild, moderate, and severe according to the amount of contrast material filling the left ventricle during diastole; the numbers of

The Journal of Thoracic and Cardiovascular Surgery

4 8 Soorae et al.

Table IV. Preoperative aortic gradients Fascia lata

Homograft

Valve pathology

No. of patients

Peak systolic gradient (mm. Hg)

No. of patients

Peak systolic gradient (mm. Hg)

Aortic stenosis Mixed Aortic regurgitation Totals

12 8 18 38

70-140(97) 20-80 (43) 0-24 (18)

13 11 14 38

60-136(87) 15-77 (35) 0-30 (10)

Table V. Aortic regurgitation on preoperative angiography Aortic regurgitation None Mild Moderate Severe

Fascia lata (n = 38) 5 9 16

Table VI. Macroscopic pathology of aortic valve at operation Type of valve

Homograft (n = 38) 6 7

11 14

patients in each group were again similar in the two series (Table V). Postoperative cardiac catheterization was carried out only in patients who developed clinically significant valve incompetence. Digoxin and diuretics were discontinued 48 hours preoperatively unless the patient was too sick to allow withdrawal, but the potassium supplements were usually continued until the day of the operation. Antibiotics were given for 5 days postoperatively and were started immediately before bypass was begun. Three-cusp autologous fascia lata valves were mounted on support frames made of titanium and covered with Dacron velour. The valves were constructed free hand under sterile conditions in the operating theater immediately after induction of anesthesia and were used in all 38 patients under review. The method of construction was essentially similar to that described by Ionescu and Ross.1 The homograft aortic valves were removed under unsterile but clean conditions in the mortuary within 24 hours of death of the donors, who had died either of trauma or of noninfectious disease. The valves were kept in a freezer at —70° C. before they were dissected. After dissection, the size was recorded and the valves were stored at 4° C. in an antibiotic solution consisting of neomycin (1 Gm.), streptomycin (1 Gm.), Mycostatin (125,000 units), and penicillin (2,000,000 units) made up in 150 ml. of normal saline. If not used, the valves were discarded after 6 weeks. The average period of preservation before insertion was 23 days. All valve constructions and replacements were car-

Pathology Calcific Rheumatic Bicuspid Infective endocarditis Others Marfan syndrome Syphilitic

Fascia lata (n = 38)

Homograft (n = 38)

12 14 4 6

18 14 2 4 0 0

ried out by two of us (J. C. and P. J. M.). The operation was performed with the aid of moderate hypothermia and cardiopulmonary bypass, for which a disposable bubble oxygenator* and hemodilution were used; physiological flow rates were maintained with roller pumps.2 During cardiopulmonary bypass, the aorta was cross-clamped and continuous coronary perfusion was used for myocardial protection. The types of valvular disease seen at operation are listed in Table VI. After valve excision, the unmounted homografts were inserted with interrupted sutures over the lower part of the valve and continuous sutures over the upper part. The stented fascia lata valves were inserted with a single row of interrupted sutures. An analysis of valve sizes inserted in both series is shown in Fig. 1. Twenty-nine of the fascia lata valves were less than 23 mm. in internal diameter, whereas 28 of the homograft valves were 23 mm. or larger (p = 0.001). The mean time on cardiopulmonary bypass was 96 minutes in the fascia lata group and 130 minutes in the homograft series. Anticoagulants (Persantin and warfarin) were used in the fascia lata series for the first 3 months *Rygg-Kyvsgaard disposable bubble oxygenator (Polystan, Copenhagen, Denmark).

Volume 76 Number 1 July, 1978

Aortic valve replacement

49

'2n FASCIA LATA HOMOGRAFTS 10-

8-

z

UJ I—

<

o 2

2-

0J

L_ 18

19

20

21

22

23

24

25

26

27

VALVE SIZE (INTERNAL DIAMETER in mm.)

Fig. 1. Analysis of fascia lata and homograft valve sizes. postoperatively, after which they were discontinued. No anticoagulants were used in the homograft series. After discharge from the hospital, the patients were followed in the out patient department at 6 weeks, 4 months, 6 months and, subsequently, if they remained well, at yearly intervals. Assessment of symptoms and full clinical examination, with particular attention to the appearance of new diastolic murmurs, were made at all these follow-up visits. A posteroanterior chest roentgenogram and an electrocardiogram were taken at all these visits. Statistical techniques such as chi square analysis, exact probability test, and t test were used for comparison of the data. Actuarial curves for survival of patients with a normally functioning valve and no diastolic murmurs were constructed. We are aware of the retrospective nature of this study and the problems of interpretation of the statistical analysis associated with small groups. Results The early and late mortality rates are compared in Table VII. The operative mortality rate was higher in patients with fascia lata valves than in patients with homografts (13 compared to 8 percent), but this difference was not statistically significant (p = 0.7). There

Table VH. Deaths Homograft

Fascia Lata No. of deaths

Percent

No. of deaths

Early Late

5 3

13 8

3 3

8 8

Totals

8

21

6

16

Deaths

Percent

were three late deaths in each of the series, for a late mortality rate of 8 percent in each. The total mortality rate for the fascia lata series was 21 percent and that for the homograft series, 16 percent. All those patients who died in the hospital symptomatically belonged to Class III or IV, had left ventricular hypertrophy with a strain pattern on the electrocardiogram, and had a mean cardiothoracic ratio of 60 percent on a posteroanterior chest roentgenogram. The causes of early and late death are analyzed in Table VIII. There were three valve-related deaths in the fascia lata series and two in the homograft valve series. The valve-related deaths in the fascia lata series occurred late, at 3 months, \Vi years, and 5% years, whereas the two valve-related deaths among patients with a homograft valve occurred in the early post-

The Journal of Thoracic and Cardiovascular Surgery

5 0 Soorae et al.

Table VIII. Analysis of deaths Fascia lata Deaths Early

Late

Valve-related deaths

No. of deaths

Homograft No. of deaths

Cause of death

5(13%) 2 2 1

Dysrhythmias Technical Septicemia

3 (8%) 1 1 1*

Fungal endocarditis (3 mo.) Cusp rupture (l'/i yr.) CHF, pulm. embolus (5% yr.)

Cause of death

3 (8%)

3

1 2 3 (8%) 1 1 1

Myocardial infarction Endocarditis Dysrhythmia (3 mo.) Gunshot wounds (5 yr.) Carcinomatosis, ca of body of uterus (7VS yr.)

2

Legend: CHF, Congestive heart failure. ♦Died while awaiting reoperation.

Table IX. Incidence of complications in early postoperative period Type of valve Complications Hemorrhage Infection Arrhythmias Neurological Others Totals

Fascia lata

Homografts

2 6 7 1 4

1 7 10 3 4

20

25

operative period, and both were due to infective endocarditis. None of the late deaths in the homograft series could be attributed to valve failure. One patient with a fascia lata valve who died of pulmonary embolism while awaiting reoperation had gross aortic regurgitation with left ventricular failure. The early postoperative complications are analyzed in Table IX. More patients with homograft valves had complications, but there was no significant difference between the two series. In two patients with fascia lata valves, minor thromboembolic episodes 4 months and 7 months postoperatively resulted in transient left hemiparesis and transient blindness. Only one patient in the homograft series had transient left hemiparesis at 4 months. No long-term anticoagulants were necessary. Both of these valves were susceptible to infective endocarditis. The incidence of early and late endocarditis is given in Table X. Early endocarditis was defined as endocarditis occurring within 30 days of operation. One patient with a fascia lata valve contracted endocarditis early in the postoperative period, as compared with three patients with homograft valves, but

this difference was not statistically significant (p = 0.4). The incidence of late endocarditis was also similar: two cases in the fascia lata series and three in the homograft series (Table X). Streptococcus viridans was the most common causative organism for endocarditis. Other organisms encountered were Staphylococcus (coagulase negative), Escherichia coli, Proteus, and Klebsiella aerogenes; one patient with E. coli endocarditis, treated with large doses of broad-spectrum antibiotics, died of monilial fungal endocarditis. The over-all incidence of aortic valve regurgitation indicative of tissue deterioration or paravalvular leak in the two series is shown in Fig. 2. At the conclusion of the series, 14 patients (42.5 percent) with fascia lata valves had diastolic murmurs as compared with 16 patients (46 percent) in the homograft series. Nineteen patients in each of the series had no aortic diastolic murmurs. The time of appearance of aortic diastolic murmurs in the two series are compared in Fig. 3. The incidence of new murmurs appearing each year after the first year is similar in the two series: one or two murmurs appeared per year until, at the end of 6 years, there were 14 diastolic murmurs in the fascia lata series and 16 in the homograft series. Categorization of aortic diastolic murmurs into those that were hemodynamically insignificant, those that were significant, and those that resulted in valve replacement is shown in Fig. 4. An insignificant murmur was defined as a nonprogressive low-grade murmur in an asymptomatic patient with normal diastolic and pulse pressures and an unchanging electrocardiogram and chest roentgenogram; all other aortic diastolic murmurs were considered significant. An early murmur was defined as one which developed during the first

Volume 76 Number 1 July, 1978

Aortic valve replacement

5 1

Table X. Analysis of postoperative infective endocarditis Homograft

Fascia lata Infective endocarditis

No. of cases

Time of onset

Outcome

No. of cases

Time of onset

Outcome

Early

1 (2.5%)

5th day

Died (3 mo.)

3 (8%)

6th day 10th day 21st day

Died A&W Died

4 yr. 5'/2 yr.

A& W A& W

3 (8%)

2yr. 4 yr. 6 yr.

A&W A& W A&W

Late

6(16%)

Total incidence Legend: A & W, Alive and well following valve replacement.

Table XI. Analysis offunctional state preoperatively and at the conclusion of the series January, 1977 Preoperative

Original valve, noA.D.M.

Original valve, A.D.M.

N.Y.HA. Class

F.L.

H.G.

F.L.

H.G.

F.L.

1 11 III IV

2 14 20 2

1 16 19 2

14 2 0 0

10 5 1 0

Totals

38

38

16

16

Original valve replaced

Total

H.G.

F.L.

H.G.

F.L.

H.G.

4 2 2 0

6 3 1 0

5 1 0 0

5 1 0 0

23 5 2 0

21 9 2 0

8

10

6

6

30

32

Legend: N.Y.H.A., New York Heart Association. A.D.M., Aortic diastolic murmur. F.L., Fascia lata. H.G., Homograft.

postoperative year. Further analysis showed that early significant murmurs developed in three patients (fascia lata none, homograft three) and de novo late significant murmurs developed in five patients (fascia lata three, homograft two). Six of the 13 early insignificant murmurs became significant (fascia lata four, homograft two), and four of the nine late insignificant murmurs became significant (fascia lata two, homograft two). At the conclusion of the study, five patients with fascia lata valves and seven with homograft valves had hemodynamically trivial aortic regurgitation, and three patients in each series who had clinically significant aortic incompetence were awaiting cardiac catheterization. Six patients in each series who had significant murmurs required reoperation for a grossly incompetent valve; none of them died. Valve failure in these series was defined as replacement of the valve with another device, valve-related death, and significant aortic regurgitation clinically or on cardiac catheterization. Twelve (31.5 percent) fascia lata valves failed and 11 (29 percent) homograft valves. Six patients with fascia lata valves required reoperation for valvular incompetence. Cusp detachment from the pillar was noted in four patients, although the fascia lata appeared healthy. Histologically, all of these cusps

were found to be acellular, and avascular dense collagenous tissue with deposition of calcium was noted in two of the valves studied. In the other two patients the valvular tissue was disorganized by infective endocarditis. In the homograft series, one valve failed because of cusp shortening, which resulted in a triangular orifice, another failed because of cusp detachment, and a third failed because of a split through the middle of the right coronary cusp giving rise to incompetence. The other three valves were found to be affected by endocarditis. Valve stenosis has not been a cause of valve failure in these series, although low-grade, localized basal systolic murmurs have been noted in all of the patients. The number of survivors with a normally functioning valve and without a diastolic murmur was subjected to actuarial analysis (Fig. 5). There is a difference between the two series in the first year, but thereafter the two graphs are parallel and almost coincide at 6 years. Evidently, there is very little difference between the over-all incidence and the time of appearance of valve deterioration. Table XI analyzes the functional state of the patients preoperatively and at the conclusion of the series. The patients were subgrouped into those without aortic dia-

The Journal of Thoracic and Cardiovascular Surgery

5 2 Soorae et al.

Fig. 2. Incidence of aortic diastolic murmurs (ADM).

S

OFASCIA LATA

14 (42.5%)

• HOMOGRAFTS 16 (46%) 2 ■

o 4i—i 0 6/12

1 1

1 2

1 3

1 4

1 5

1 6YRS.

TIME

Fig. 3. Time of appearance of aortic diastolic murmurs. stolic murmurs, those with aortic diastolic murmurs, and those who have had their valve replaced. Preoperatively, the majority of patients in both series were in Class II or III, and there were a similar number in each class. In January, 1977, the majority of patients in both series were in Class I, with a similar number of patients in this class. The number of patients in the three subgroups was also similar in both the series, the majority of patients being in Class I. The symptomatic patients had coronary artery disease, hypertension, or other associated valvular lesions. Discussion Survival after aortic valve replacement is dependent upon pre-existing heart disease, the operative technique, the long-term mechanical function of the valve, and the incidence of complications. There is no control over pre-existing heart disease, and the operative risks

for all types of valve replacements are similar in most centers. Therefore, the incidence of complications such as thromboembolism, hemodynamic function of the valve, and late valve failure become of paramount importance in valve selection. The development of tissue valves was a natural step in the search for an "ideal valve," because of the problems of hemolysis, mechanical failure, residual gradients, infection, and, most important, thromboembolism associated with the use of prosthetic valves. Murray3 discussed the long-term function of an aortic homograft in the descending aorta. Ross4 in 1962 and Barratt-Boyes5 in 1964 first advocated the use of homograft aortic valves in the subcoronary position. Senning and Tsakiris6 first used autologous fascia lata strips to construct aortic valve cusps in 1964. Ionescu and Ross1 subsequently developed frame-mounted fascia lata valves which permitted replacement of all the cardiac valves. There is universal disagreement about the superiority of one type of heart valve over another, and various comparative studies between prosthetic and tissue valves have been conducted. Pine and associates7 found that in two series of patients at equal risk, mortality and valve failure were similar for homograft and prosthetic aortic valve replacement. Angell, Angell, and Sywak,8 in a prospective, randomized study, found that there was no significant functional or hemodynamic difference between the homograft and prosthetic valve but there was improvement in patient morbidity and mortality rates with the homografts. Karp and associates9 showed that the cloth-covered prosthesis in unanticoagulated patients is not as satisfactory a substitute as the homograft valve, whereas Wallace10 concluded that mechanical prostheses were a better choice than homografts for most of his patients. However, there is a

Volume 76

Aortic valve replacement

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53

July, 1978

FASCIA

LATA

HOMOGRAFT

Fig. 4. Analysis of aortic diastolic murmurs. *One patient died while awaiting reoperation. lack of comparative long-term follow-up data regarding the fate of isolated homografts and fascia lata valves in the aortic position, especially from one surgical unit in which all the patients have been operated upon by the same surgeons. The early clinical results with fascia lata valves were encouraging.11, 12 As clinical experience grew, it became evident that there was a delayed incidence of valve failure owing to degenerative changes and infective endocarditis. Fascia lata valves in the mitral position are subject to early cusp shrinkage and thickening and thus early valve failure, but they continue to function well in the aortic position.13, H As a result of this difference, Trimble and colleagues15 consider that fascia lata valves offer a suitable alternative to other forms of aortic valve replacement. There are others, however, who believe that homografts are better for aortic valve replacement than fascia lata.16 The incidence of homograft valve degeneration varies with the type of sterilization techniques used. These have varied from procurement under sterile conditions to sterilization by gamma irradiation, ethylene oxide, propiolactone, mercurate and tanning agents like formalin and glutaraldehyde. The incidence of valve failure owing to rupture or tearing of cusps is lower if the valve is treated with antibiotics than if it is irradiated or treated chemically.17 Technical errors may well cause valve failure, not only from dehiscence, but also from calcification, cusp prolapse, tears, and perforation.18 The incidence of homograft and fascia lata valve failure was similar in our series. The number of patients developing diastolic murmurs, the time of appearance of the murmur after operation, and the severity of the murmurs were also similar in both types of valves (Fig. 3). There was a high incidence of diastolic murmurs in both series in the early postoperative period. This high

.FASCIA LATA

53%

• HOMOGRAFTS 5 1 %

0+i—i r 0 6/12 1

3

6 YRS.

TIME

Fig. 5. Actuarial analysis of survivors without aortic diastolic murmurs. early incidence is most likely due to technical errors in valve construction with fascia lata and greater difficulties of homograft insertion. Approximately 40 percent of the patients, seven with homografts and five with fascia lata valves, who developed diastolic murmurs had hemodynamically insignificant, nonprogressive aortic regurgitation at the conclusion of the study. Some of these valves undoubtedly will develop increasing regurgitation and eventually will have to be replaced. Therefore, the need for regular reviews and indefinite follow-up is mandatory in all cases of aortic valve replacement. Systemic hypertension in the homograft series has not been a contributary cause of late aortic regurgitation, as has been reported.19

54

Soorae et al.

There was a higher incidence of both early and late endocarditis in the homograft series, although the differences were not statistically significant. The higher incidence of early endocarditis in the homograft series could well be due to inadequate sterilization of the valve. There is a possibility of contamination of the valve during construction in one case of early endocarditis in the fascia Iata series. However, this does not explain the late susceptibility to this complication in both types of valves. Early endocarditis carried a poor prognosis. Three out of four such patients died whereas all five patients with late endocarditis were treated successfully by antibiotics and valve replacement. Rothlin and Senning 20 have made a similar observation from their experience with fascia lata valves, describing the poor prognosis of endocarditis in the first postoperative year when eight of their 10 patients died. On the other hand, seven of their nine patients who had late endocarditis survived. The total incidence of bacterial endocarditis of 16 percent in patients with homografts is relatively higher than that in some other series of homografts 18,21 and prosthetic valves. 22 The over-all 69 month survival rate of 84 percent in the homograft series is similar to that of some of the larger series reported in the literature with follow-up periods of from 48 to 120 months. 21, 23, 24 BarrattBoyes and associates 23 had a 77 percent 6 year survival rate, and Anderson and Hancock 21 reported a 79 percent 5 year survival rate with homografts. The mean 73 month survival rate with frame-mounted autologous fascia lata valves was 79 percent in our series. Trimble, 1 5 Joseph, 16 and their colleagues reported 86 percent survival rates at Vh and 3 to 4 years, respectively. It is difficult to make any valid comparisons, because no long-term follow-up comparative data for fascia lata aortic valves are available in the literature. Almost 50 percent of the survivors in both of our series had a normally functioning valve after 6 years. In the series reported by Barratt-Boyes and associates, 23 48 percent of the patients had perfect valve function at 6 years. The actuarial curves for patients surviving with a normally functioning valve run almost parallel after 1 year; this indicates that the incidence and the time of appearance of valve deterioration is similar in the two types of tissues. Late hemodynamic studies were not performed in our series, but postoperative cardiac catheterization carried out by others 13 ' 16 has shown no progressive stenosis and no valve calcification radio logically in the fascia lata valves; where systolic gradients were found, they were related to the small orifice size of the valve.

The Journal of Thoracic and Cardiovascular Surgery

The incidence of thromboembolism was also relatively small in the present series and has not been a major problem. Tissue valves have a distinct advantage over prosthetic valves in this regard. Homografts offered two main advantages over fascia lata valves: First, it was possible to insert homograft valves with a bigger internal diameter (Fig. 1), which can be of great importance in patients with narrow aortic roots. Second, there were no late valve-related deaths in the homograft series, whereas all the late deaths in the fascia lata series were valve related. The two valve-related deaths in the homograft series occurred in the early postoperative period, both due to infective endocarditis. The long-term results of aortic valve replacement with fascia lata and homograft valves are remarkably similar with regard to early and late mortality, susceptibility to infective endocarditis, incidence of thromboembolism, long-term durability, over-all survival, and survival with an intact valve. It is therefore concluded that there is little to choose between the two types of valves for aortic valve replacement and that the search for an ideal valve should continue. If fascia lata, as we believe, is no longer acceptable as a satisfactory valve substitute, then homograft valves should be placed in the same category. REFERENCES 1 Ionescu MI, Ross DN: Heart valve replacement with autologous fascia lata. Lancet 2:335, 1969 2 Cleland J, Molloy PJ: Thrombo-embolic complications of the cloth-covered Starr-Edwards prostheses No. 2300 aortic and No. 6300 mitral. Thorax 28:41, 1973 3 Murray G: Homologous aortic valve-segment transplants as surgical treatment for aortic and mitral insufficiency. Angiology 7:466, 1956 4 Ross DN: Homograft replacement of the aortic valve. Lancet 2:487, 1962 5 Barratt-Boyes BG: Homograft aortic valve replacement in aortic incompetence and stenosis. Thorax 19:131, 1964 6 Senning A, Tsakiris A: Erste Ergebnisse einer neuen operativen Korrektur der Aortenklappenfehler. Cardiologia (Basel) 44:259, 1964 7 Pine M, Hahn G, Paton B, Pappas G, Davies DH, Steele P, Pryor R, Blount SG: Homograft and prosthetic aortic valve replacement. A comparative study. Circulation 54:Suppl 3:84, 1976 8 Angell WW, Angell JD, Sywak A: Selection of tissue or prosthetic valve. A five-year prospective, randomized comparison. J THORAC CARDIOVASC SURG 73:43, 1977

9 Karp RB, Kirklin JW, Kouchoukos NT, Pacifico AD: Comparison of three devices to replace the aortic valve. Circulation 49,50:Suppl 2:163, 1974 10 Wallace RB: Tissue valves. Am J Cardiol 35:866, 1975

Volume 76 Number 1 July, 1978

11 Edwards WS, Karp RB, Robillard D, Kerr AR: Mitral and aortic valve replacement with fascia lata on a frame. J THORAC CARDIOVASC SURG 58:854, 1969

12 Ionescu MI, Ross DN, Deac R, Grimshaw VA, Taylor SH, Whitaker W, Wooler GH: Autologous fascia lata for heart valve replacement. Thorax 25:46, 1970 13 Petch M, Somerville J, Ross D, Ross K, Emanuel R, McDonald L: Replacement of the mitral valve with autologous fascia lata. Br Heart J 36:177, 1974 14 Ionescu MI, Pakrashi BC, Mary DAS, Bartek IT, Wooler GH: Replacement of heart valves with frame-mounted tissue grafts. Thorax 29:56, 1974 15 Trimble AS, Gunstensen J, Silver MD, Aldridge HE, Schwartz L, Morch JE: Aortic valve replacement with fascia lata. An encouraging late study. J THORAC CARDIOVASC SURG 68:219, 1974

16 Joseph S, Somerville J, Emanuel R, Ross D, Ross K: Aortic valve replacement with frame-mounted autologous fascia lata. Long-term results. Br Heart J 36:760, 1974 17 Gonzalez-Lavin L, Ross D: Homograft aortic valve replacement. A five-year experience at the National Heart Hospital, London. J THORAC CARDIOVASC SURG 60:1,

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18 Moore CH, Martelli MD, Al-Janabi N, Ross DN: Analysis of homograft valve failure in 311 patients followed up to 10 years. Ann Thorac Surg 20:274, 1975 19 Layton C, Brigden W, McDonald L, Monro J, McDonald A, Weaver J: Systemic hypertension after homograft aortic valvar replacement. Lancet 2:1343, 1973 20 Rothlin M, Senning A: Ten years' follow up after fascia lata replacement of the aortic valve. J Cardiovasc Surg Spec. No. 339, 1973 21 Anderson ET, Hancock EW: Long-term follow-up of aortic valve replacement with the fresh aortic homograft. J THORAC CARDIOVASC SURG 72:150, 1976

22 Armoury RA, Bowman FO, Malm JR: Endocarditis associated with intracardiac prostheses. J THORAC CARDIOVASC SURG 51:36, 1966

23 Barratt-Boyes BG, Roche AHG, Whitlock RML: Six year review of the results of freehand aortic valve replacement using an antibiotic sterilized homograft valve. Circulation 55:353, 1977 24 Ross D: Long term results in aortic homografts. J Cardiovasc Surg Spec. No. 350, 1973