Replacement of heart valves with frame-mounted tissue grafts

Ionescu, M. I., Pakrashi, B. C., Mary, D. A. S., Bartek, I. T., and Wooler, G. H. (1974). Thorax, 29, 56-67. Replacement of heart valves with frame-mounted tissue grafts. Between April 1969 and March 1973, 213 patients had heart valve replacement with frame-mounted autologous or homologous fascia lata or with heterologous pericardial grafts. There were 111 single aortic, 95 single mitral, and seven tricuspid valve replacements.     

A fascial frustum valve for aortic valve replacement

The promising qualities of autologous fascia lata in heart valve replacement have resulted in a search for improved methods of fascial heart valve manufacture. This paper describes a simply made and inserted and reliably competent unsupported fascial valve for aortic valve replacement.     

A two-year experience with supported autologous fascia lata for heart valve replacement

Over a two-year period 262 supported living fascia lata valves were implanted in 201 patients. Early results were satisfactory from the point of view of valve function. After several months it became obvious that autologous fascia lata valves behave very differently in each of the three positions. A critical analysis is presented of 193 valves that were available for follow-up. After two years' experience with this method of valve replacement, it is the opinion of the authors that supported, living fascia lata valves are unsuitable for tricuspid valve replacement. In the mitral position they have shown an increasing incidence of systolic murmurs and evidence of regurgitation. The supported fascia valves have given the best functional results in the aortic position; however, not enough time has elapsed to assess their long-term function.     

Autologous fascia lata for heart valve replacement

To obviate the drawbacks of prosthetic devices and in search of a better substitute for diseased heart valves a technique of using autologous fascia lata grafts attached to a support frame was developed. The technique of preparing mounted fascia lata grafts is briefly outlined and their surgical implantation into the mitral, tricuspid, and aortic areas is described. Since April 1969, 83 fascial grafts have been inserted into 76 patients with very good immediate and short-term results. Ten patients succumbed within the operative period. None of these deaths was due to failure of the graft per se. Thromboembolic manifestations have been completely absent although anticoagulants were not used. All sixty-six survivors are very much improved. Data concerning the structure and function of fascia are presented and the experimental and clinical use of fascia lata in extracardiac and cardiac surgery is reviewed. The use of autologous, living, fascia lata valves is considered to be a better approach for heart valve replacement because autologous fascia maintains its structure unchanged after transplantation and, being under mechanical stimulation, it retains its functional properties.     

Opening characteristics of three-cusp tissue heart valves

Since April 1969, frame-mounted three-cusp fascia lata and pericardial valves have been used in over 200 patients for heart valve replacement. Six autologous fascia lata valves have been removed from the mitral position because of regurgitation produced by shrinkage of one or two cusps. To elucidate the cause and mechanism of graft failure the opening characteristics of fascia lata and Silastic valves were studied in a steady state flow rig.     

Autologous fascia lata transplantation for heart valve replacement: A two-year experience at the National Heart Hospital, London

Between April 1969 and December 1970, 201 patients underwent 262 valve replacements with frame-mounted autologous fascia lata valves in the aortic, mitral, and/or tricuspid positions at the National Heart Hospital. A single fascia lata valve was inserted in 146 patients and multi-valve replacement was performed in 55 instances. Hospital and late mortality are comparable with that following other procedures of heart valve replacement. One hundred and fifty-four patients with 193 fascia lata valves were available for follow-up. A retrospective analysis of this method of valve replacement has been undertaken to assess the suitability of fascia lata as a heart valve substitute as well as the clinical results achieved by this method of valve replacement.     

Fascia lata valves: a clinicopathological study.

Sixteen frame-mounted fascia lata valves removed from the mitral, aortic or--in one patient--pulmonary position have been detailed histologically. These valves had remained in 15 patients (11 men and four women) for periods varying between 10 and 44 months. The reason for the original transplantation was either chronic rheumatic endocarditis or calcific aortic disease. In the mitral position, the leaflet in position nearest the site of the original anterior mitral valve cusp showed the least changes. The remaining two leaflets of the fascia lata valve in the mitral position, as well as those removed from the aortic or pulmonary position, showed more severe changes; these consisted of degeneration of collagen tissue and often a severe decrease of nuclei belonging to the fibroblastic series. These changes, as well as superimposition of fibrin or fibrous tissue, tended to become more pronounced the longer the valve had remained in the patient. Viability studies in valves removed from two patients have also been undertaken showing very greatly reduced activity. The possible causes for valve dysfunction have been reviewed, and the findings in this study suggest that contraction of fibrous tissue, which sandwiches the fascia lata valve cusps, may contribute to failure of satisfactory valve function. It is concluded that fascia lata forms a poor substitute for replacement of diseased cardiac valves.     

Aortic valve replacement with frame-supported autologous fascia lata grafts. II. Clinical and laboratory findings.

Thirty-five patients with a frame-supported autologous fascia lata graft implanted in the aortic annulus were investigated 11 to 36 months after operation. The group comprised 7 patients with pure aortic stenosis, 11 with combined stenosis and incompetence and 17 with pure aortic incompetence. Seven patients had concommitant mitral valve disease. The follow-up investigation included ECG, a work test on a bicycle ergometer, dynamic spirometry, roentgenological heart volume determination and haematological "screening tests" for intravascular haemolysis. Concomitant with a marked subjective improvement of the patients, there was a considerable objective improvement, as judged by physical working capacity, ECG signs of left ventricular hypertrophy and heart volume. The serum haptoglobin values were somewhat lower postoperatively (mean value 44 mg%), but no ahaptoglobinaemia occurred. Thus, no definite signs of intravascular haemolysis were noted. No thrombo-embolism occurred within this observation period, despite the fact that none of the patients with isolated aortic valve replacement were treated with anticoagulants. This investigation shows that a frame-supported autologous fascia lata valvular graft in the aorta can function well during a period of up to 3 years.     

Aortic valve replacement with frame-supported autologous fascia lata grafts. III. Haemodynamic and angiographic findings.

Thirty-two patients with a frame-supported, autologous, fascia lata graft implanted in the aortic annulus were investigated 11 to 36 months after the operation. The group comprised 7 patients with pure aortic stenosis, 10 with combined aortic stenosis and aortic incompetence and 15 with pure aortic incompetence. Six patients had concomitant mitral valve disease. The follow-up investigation included right heart and transseptal left heart catheterization, left ventricular angiocardiography through the transseptal route and a retrograde, supravalvular aortography with the cinétechnique. Cardiac output was essentially unchanged postoperatively. However, it had increased considerably in some patients in whom it was very low before the operation. Left ventricular systolic pressure decreased particularly in patients with pure aortic stenosis. Left ventricular enddiastolic pressure decreased from 12 to 7 mmHg at rest and from 25 to 18 mmHg during exercise. Left atrial (or pulmonary arterial wedge) mean pressure decreased from 14 to 2 mmHg at rest, and from 27 to 16 mmHg during exercise. In 76% of the patients a slight (grade I or II) central or paravalvular aortic regurgitation was observed on cinéangiograms. Regurgitation of grade III was found in one patient. Technical details in the construction of the valve, as well as structural changes in the fascia lata which may be responsible for stenosis and incompetence in some of these valves are discussed. Thus, although even patients with defective valves have shown considerable improvement, a close and continuous follow-up of these patients is necessary.     

Fascia lata aortic valve reconstruction: long-term results in 33 patients

Aortic valve reconstruction with autologous fascia lata was performed in 33 patients (mean age 35 years) in 1966 and 1967. Eighty-two per cent had cusp extension rather than replacement, while 33% required additional intracardiac procedures. There were seven hospital deaths (21%) and 11 late deaths (33%), a total mortality of 54% over four years. Six late deaths followed reoperation for recurrent incompetence, and two other patients survived reoperation. Endocarditis (rickettsial, fungal, and bacterial) occurred in five cases, all required reoperation for incompetence, and four died. Sixty-nine per cent of the survivors of operation left hospital with competent valves and did better than the 31% with leaking valves in terms of late deaths, endocarditis, and reoperation for incompetence. Of the 15 patients (45%) still alive, 13 still have their original fascial valve, and of these only two (or perhaps three) have no diastolic murmur. Seven have insignificant murmurs and three have aortic incompetence. These poor results, particularly in the long term, make us sceptical about current enthusiasm for fascia lata heart valves.     

Brucella melitensis endocarditis: successful treatment of an infected prosthetic mitral valve

O'Meara, J. B., Eykyn, Susannah, Jenkins, B. S., Braimbridge, M. V., and Phillips, I. (1974).Thorax, 29, 377-381. Brucella melitensis endocarditis: successful treatment of an infected prosthetic mitral valve. A 38-year-old man had a mitral valve replacement for rheumatic calcific mitral stenosis and regurgitation; following this operation he remained well for 10 months. He then presented with cough, abdominal pain, and rigors, and Brucella melitensis type 3 was repeatedly isolated from blood cultures. His clinical condition deteriorated rapidly and an emergency valve replacement was performed. He was then treated with co-trimoxazole for 12 months and made an excellent recovery. This is the first reported case of brucella endocarditis arising de novo on a prosthetic heart valve.     

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 number, 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 of 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 satisafactory valve substitute, then homograft valves are not acceptable either.     

Reconstruction of right ventricular outflow with a valved homograft conduit

Wheatley, D. J., Prusty, S., and Ross, D. N. (1974).Thorax, 29, 617-623. Reconstruction of right ventricular outflow with a valved homograft conduit. Since 1966 a conduit of homograft ascending aorta with its valve has been used for reconstruction of the right ventricular outflow. This technique has been applied to 123 operations for pulmonary autograft replacement of the aortic valve, 48 operations for correction of severe Fallot's tetralogy or pulmonary atresia, five operations for truncus arteriosus, two operations for transposition of the great arteries with ventricular septal defect, and six operations for tricuspid atresia or common ventricle. Ease of insertion and satisfactory function have encouraged us in the use of this form of conduit.     

Haemodynamic results of replacement of mitral and aortic valves with autologous fascia lata prostheses

Twelve patients undergoing aortic and 28 undergoing mitral valve replacement with autologous fascia lata valves were studied before and six months after surgery. One aortic and 10 mitral valves were found to be significantly incompetent. Of the incompetent mitral valves, two appeared to have perivalvular leaks. Six of the remainder were associated with abnormal ventricular filling patterns. Valve failure was much less common when the design was modified to provide a loose cusp structure; out of 12 such valves none was incompetent. Transvalvular gradients persist with fascial valves though they are lower than with most mechanical prostheses. Ventricular function was greatly improved in successful aortic replacement but remained impaired in the case of mitral replacement. Valve failure appeared to be associated with, or accelerated by, haemodynamic stress rather than due to inevitable degenerative pathological processes.     

Histopathology of `fresh'' human aortic valve allografts

Gavin, J. B., Barratt-Boyes, B. G., Hitchcock, G. C., and Herdson, P. B. (1973).Thorax, 28, 482-487. Histopathology of `fresh' human aortic valve allografts. Six aortic valve allografts were studied histologically after having functioned in patients as aortic valve replacements for 14 to 442 weeks. The grafts initially had been collected under sterile conditions from cadavers and stored in Hanks's balanced salt solution for 2 to 24 days before use. All grafts showed a cellular reaction along the host graft interface characterized by macrophages, lymphocytes, and organizing granulation tissue, and there was a progressive replacement of the donor aortic sleeve by host collagenous tissue. Sheaths of cellular, avascular host tissue extended from the margins of all grafts over their intimal surfaces and, in those which had been in place more than 36 weeks, this tissue had resulted in thickening of the proximal parts of one or more cusps. In one graft this thickening extended almost to the free margins of the cusps. While the leaflets of the graft at 14 weeks were virtually acellular, older grafts contained cellular areas with active fibroblasts in the proximal regions of the cusps as well as acellular regions which generally were more distally placed. Macrophages were always present along the interface between cellular and acellular areas. These observations indicate that there is a gradual replacement fibrosis of the graft by the host which proceeds in different grafts, and even different cusps in the same graft, at different rates.     

C-reactive protein as a marker of severe calcification among patients with bicuspid aortic valve disease

Background. Bicuspid aortic valve (BAV) may be associated with aneurysmal dilatation of the ascending aorta, even after successful aortic valve replacement. There are as yet no biomarkers that correlate with the progression of such disease. Elevated levels of C-reactive protein (CRP), a marker of acute inflammation, are seen in chronic rheumatic valve disease, especially those with multivalvular disease, and have been shown to return to normal after valve replacement. We hypothesized that dilatation of the ascending aorta with BAV would be associated with ongoing inflammation, and, accordingly, elevated levels of CRP. Methods. High-sensitivity CRP levels [normal 0.02-0.8 mg/dl] were assayed from blood samples drawn in the operating room prior to cardiopulmonary bypass in 25 patients (4 female and 21 male, mean age 50 years, range 18-72 years) with bicuspid aortic valve disease undergoing valve replacement or repair. Preoperative cardiovascular risk factors for coronary artery disease, as well as valve function, area, and ascending aortic diameter based on echocardiogram were noted. Degree of valve calcification (none to minimal or moderate to severe) was recorded based on surgical observation or pathology report. None of the patients had active infections, tumors, or acute myocardial infarction. Results. There was no correlation of the CRP level to aortic diameter, valve area, patient age, gender, or body mass index (BMI). CRP levels were higher among patients with moderate-to-severe valvular calcification (n = 13, mean 0.711 ± 2.22 mg/dl) compared with none or minimal valvular calcification (n = 12, mean CRP 3.071 ± 5.62 mg/dl) (P = 0.0065). This difference remained statistically significant after excluding patients with coronary artery disease (n = 13). There was a trend for higher CRP level among patients with aortic stenosis (mean CRP 5.378 mg/dl) compared to those with aortic regurgitation (mean CRP 0.103 mg/dl) (P = 0.058). Conclusions. Elevated CRP among patients with BAV did not correlate with aortic diameter, but was associated with advanced calcific valve disease. This assay may prove useful in understanding the pathogenesis of calcification in this group of patients and to identify those with BAV at risk for progressive aortic valve disease.     

Mitral Valve Replacement with Dura Mater Bioprostheses

Dura mater bioprostheses for cardiac valve replacement were first introduced in Brazil. They have been used since 1975 at the National Heart Hospital, London, as a mitral valve replacement instead of fascia lata valves or inverted aortic homograft valves. During this period 120 patients have had dura mater valves inserted in the mitral position; 29 also received an aortic valve replacement, 6 with dura mater, 20 with an aortic homograft, 2 with an aortic xeno-graft and 1 with a prosthetic valve. Perivalvular leaks occurred with seven of these mitral valves, and another seven presented with detached cusps. All but one of these 14 valves were replaced. Emboli have occurred in four of the patients, one of whom died after 35 months with thrombus on the aortic valve, but with an unaffected mitral valve. There were 15 early deaths, a hospital mortality of 12.5%. and 10 late deaths, a postoperative mortality of 9.5%. Actuarial analysis has shown a four-year postoperative survival of 78.970.     

Cusp degeneration in frame-supported autologous fascia lata mitral valves: Clinical results in 67 patients

Sixty-seven metal-frame-supported autologous fascia lata mitral valves were placed in 67 patients. There was an operative mortality of 25% and an overall mortality of 40% within 20 months. Most of the late deaths were due to valve malfunction which occurred in 50% of survivors. Female patients demonstrated a much higher rate of valve dysfunction than did men. This mal-function of the fascial valves in the mitral position, which has not been observed in the aortic position, may be due to inappropriate design for the mitral position. The fascia is not exposed to the continued and reproducible mechanical stimulation in the atrioventricular position that it has when used as an aortic valve substitute. The mechanical properties of fascia may make it suitable for human valve substitutes but it is clear that an inverted three-cusped semilunar fascial valve will not be adequate for mitral or tricuspid valve replacements because of the haemodynamic characteristics of the atrioventricular position.     

A comparison of antibiotic-sterilized, stent-mounted pulmonary and aortic valve allografts in the mitral region of dogs

Monro, J. L., Gavin, J. B., and Barratt-Boyes, B. G. (1974).Thorax, 29, 323-328. A comparison of antibiotic-sterilized, stent-mounted pulmonary and aortic valve allografts in the mitral region of dogs. The mitral valves of 40 dogs were replaced with antibiotic-sterilized, stent-mounted semilunar valve allografts. Twenty grafts were pulmonary valves and 20 were aortic valves. Six dogs in each group died from causes related to the operation. All remaining dogs with pulmonary valve grafts died of causes related to the allograft itself (vegetative endocarditis (5), peripheral leak (1), cusp rupture (4), cusp shrinkage (4)). In the aortic valve group there were seven deaths from allograft endocarditis and one from a peripheral leak, but six dogs had competent allografts when sacrificed up to 12 months after surgery. It is concluded that the inherent strength and bulk of the aortic valve cusps make this valve a more suitable mitral valve replacement than the more delicate pulmonary valves.     

A fascia lata mitral valve based on the `frustum'' principle

A newly designed strut-supported `frustum' fascia lata valve has been described for replacement of the mitral valve. It offers the advantages of autologous tissue leaflets, ease of construction and insertion, central flow through an unobstructed mobile annulus, no ventricular outflow obstruction, and minimal intracardiac prosthetic material. Initial clinical trials which have been carried out suggest that the action of this valve allows a close approximation of the haemodynamics and movement of the normal mitral valve.