Heterograft aortic valve replacement: initial follow-up studies

Twenty-three patients have had calf or pig heterograft aortic valve replacements. Eight of these patients have required Starr-Edwards mitral ball-valve prostheses for associated mitral valve disease. There have been two hospital deaths and one late death. The 20 surviving patients have shown symptomatic improvement. Clinical evidence of incompetence is present in one patient. Pre-operative and post-operative ciné-aortograms show valve mobility with a wide central orifice. Heterografts have the advantages of homografts in being free from thromboembolism and from the need for anticoagulants; they exhibit some resistance to infection as compared with prosthetic valves. We think that heterografts, because of their wider range of size, can offer a better haemodynamic result with little clinical aortic incompetence. The long-term fate of aortic valve heterografts is not known with certainty, although the durability of homografts is better known. There is a possibility of late degeneration or rupture. If the valve continues to function normally, then it would be justifiable to recommend operation at an earlier stage in the progression of the patient's disease. At present, despite encouraging early results, we think the use of heterografts should be limited, like that of other prostheses, to those patients who show severe cardiac disability.     

Double valve replacement for acute spontaneous left chordal rupture secondary to chronic aortic incompetence

A 54 years old male with undiagnosed chronic calcific degenerative aortic valve incompetence presented with acute left anterior chordae tendinae rupture resulting in severe left heart failure and cardiogenic shock. He was successfully treated with emergency double valve replacement using mechanical valves. The pathogenesis of acute rupture of the anterior chordae tendinae, without any evidence of infective endocarditis or ischemic heart disease seems to have been attrition of the subvalvular mitral apparatus by the chronic regurgitant jet of aortic incompetence with chronic volume overload. We review the literature with specific focus on the occurrence of this unusual event.     

Biomechanics of the pulmonary autograft valve in the aortic position.

Pulmonary autograft valve replacement has been simulated by implanting the pulmonary valve into the aortic position of the same cadaver heart from both human and porcine sources. The forces acting on the pulmonary valve leaflets have been calculated on the basis of a triaxial ellipsoid mathematical model. These forces on the pulmonary autograft valve were shown to be essentially similar to those previously reported for aortic valve leaflets. Biomechanical measurements have been made on the simulated autograft valves and on the isolated pulmonary valve cusps. The tensile strengths of the pulmonary valve cusps in both circumferential and radial directions were roughly three times greater than those of aortic valve cusps. This indicated the ability of the pulmonary valves to accept, ab initio, aortic valve closing pressures. Pressure-induced changes in dimension, calculated on the basis of diameters of the simulated pulmonary autograft root, also indicated that the distensibility of the autograft valve was limited. It reached a maximum at 30 mm Hg (4 kPa) without any suggestion of further distension to the point of distortion and incompetence. The combination of the calculated forces acting on the valve and the biomechanical measurements have shown that pulmonary valves used as autograft aortic valve replacements are able to tolerate aortic pressures from the time of implantation. These experimental results from simulated autografts support the clinical use of this valve over the past 13 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.     

Radiology of homograft aortic valves

A consecutive series of 93 patients had homograft aortic valve replacement at Green Lane Hospital over a six-month period. Except for 12 assessed at one or two months, the 85 survivors were examined at three months and the clinical degree of aortic incompetence was recorded. Thirty-four of the patients did not proceed to aortography for reasons unrelated to the state of the homograft valve. Fifty-one patients were submitted to cine aortography, using a technique designed to permit a radiological assessment of the degree of aortic incompetence and to reveal details of the anatomy of the homograft valve. Following a brief review of the surgical technique of homograft aortic valve insertion, the radiological anatomy of homograft aortic valves and the mechanism of peripheral aortic incompetence in this situation are described. A radiological method of grading aortic incompetence by cine aortography is presented an the results in the 51 patients are described. The incidence of peripheral space filling and incompetence was considerably lower in the second half of the consecutive series, apparently due to a modification of the surgical technique, namely, the addition of vertical mattress sutures beneath the valve commissures to promote closure of the potential peripheral space. In the whole series of 51 patients, 71% had no significant aortic incompetence. In the latter half of the study after the vertical mattress sutures had been introduced, 84% had no significant incompetence. These results were from operations by a total of six surgeons. A smaller series of patients operated on by one surgeon using vertical mattress sutures was studied by the same methods. Eighteen of 19 patients (95%) had no significant incompetence. Good agreement was found between the radiological and clinical assessment of aortic incompetence, indicating that standard clinical methods can be applied to patients with homograft aortic valve incompetence.     

Early results of cryopreserved pulmonary allografts as aortic valve substitute.

Excellent clinical results with pulmonary autografts and experimental evidence that the pulmonary valve can withstand the higher stress in the systemic circulation led us to use the cryopreserved pulmonary allograft for aortic valve replacement. From September 1988 to March 1991, 45 consecutive patients (59.9 +/- 12.0 years, 25 men and 20 women) received a cryopreserved pulmonary allograft in the aortic position from our hospital based valve bank. All allografts were inserted freehand in the subcoronary position. There were 3 in-hospital deaths (7%) and 1 patient had severe valvular incompetence immediately postoperatively requiring reoperation after 4 weeks. Forty-one patients were followed at 3-6 month interval for 14.7 +/- 7.8 months (3-28 months) and valve performance was assessed routinely by means of color flow Doppler echocardiography: 34 patients (83%) had no or trivial aortic valve regurgitation. Valvular incompetence class II was present in 2 patients (5%) whereas 3 (7%) demonstrated class II-III. Severe aortic regurgitation (class III-IV) could be detected in 2 patients (5%). Both had to undergo reoperation 4 months and 15 months, respectively, postoperatively. Macroscopic and histological evaluation of the explanted valves demonstrated absence of significant degeneration. We assume that a mismatch in size between allograft and aortic annulus could have lead to dilatation of the allograft valve ring and consequently to valvular incompetence. Pulmonary cryopreserved allografts achieve acceptable short-term results which can be improved if initial technical problems can be avoided.     

Aortic valve replacement with unsupported fascia lata

Hearn, K., Somerville, Jane, Sutton, R., Wright, J., and Ross, D. (1973).Thorax, 28, 603-607. Aortic valve replacement with unsupported fascia lata. Twenty-five patients in the National Heart Hospital have had aortic valve replacement with unsupported autologous fascia lata and have been followed for two to three and a half years. Three patients died before leaving hospital. Nine of the 22 survivors required re-operation for severe aortic regurgitation and the other 13 developed aortic incompetence. In 11, regurgitation dated from the operation and progressed; and in 11 it appeared later and progressed. In view of the disappointing results which were obvious within six months unsupported autologous fascia lata valves have not been used for aortic valve replacement since December 1970.     

Rheumatic heart disease in the young

Pattern of rheumatic heart disease below the age of 18 in 144 autopsies was studied. Mitral valve was affected in 100% of cases. Involvement of aortic, tricuspid and pulmonary valves was seen in 63.89%, 54.86% and 12.5% respectively. Mitral stenosis was present in 80.23% cases and was of severe degree in 45%. Pure mitral incompetence was noted in 12.79% of cases. Severe degree of subvalvular disease was present in 83%. Isolated aortic incompetence was observed only in 3.17%. Tricuspid lesions were minor in most of the cases with significant stenosis only in 7.50%. Multivalvular disease was noted in 75.69% cases; but double valve and triple valve disease which possibly would have required surgery was present in only 8.33% and 3.5% cases respectively. Pulmonary vasculature was affected in 75% cases with severe changes in 25%. Calcification of valves was uncommon and was present in 6% of mitral valves and 2% of aortic valves.     

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.     

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.     

Analysis of homograft valve failure in 311 patients followed up to 10 years.

Homograft aortic valve replacement was performed in 311 patients at the tnational Heart thospital, London, between 1964 and 1973. Valve failure has occurred in 61 patients (20%), 32 of whom survived reoperation. From 1963 through 1967, 156 valves were freeze-dried and account for 56 of the valve failures. From 1968 to 1973, 118 fresh or fresh-frozen valves resulted in only 5 failures. Six general types of failure have been identified: calcification (13), dehiscence (15), infective endocarditis (17), prolapse (6), cusp degeneration (5), and tear or perforation (5). Valve failure may be due to surgical technical error resulting in dehiscence or valve incompetence, or it may be related to degenerative changes in the homograft. The clinical results, supported by gross and histological examination and viability testing, enable us to conclude that fresh or fresh-frozen valves are superior to freeze-dried valves, having resulted in only 4% valve failure over the past five years.     

Seven year experience with mounted porcine valves.

From March, 1969, through June 1976, 108 porcine aortic xenograft valves were used for mitral or aortic valve replacement in 95 patients. This experience provides one of the longest follow-ups available for evaluation of the porcine bioprosthesis. The first fifteen valves were locally mounted on Cutter stents and preserved in buffered formalin. Subsequent valves were prepared by the Edwards and Hancock Companies with glutaraldehyde preservation. Oral anticoagulation was routinely used for the first 6 weeks following surgery. Hospital mortality was unrelated to the valve type. All but four of the surviving patients with formalin preserved valves have required reoperation because of valve failure. There have been two valve failures in the patients who received gluteraldehyde valves, but there have been no embolic or thrombotic complications. Late cardiac catheterization has shown hemodynamic results equal to or better than prosthetic valves. The continuing long-term results indicate that the porcine xenograft is the valve of choice for cardiac valve replacement.     

Management of Prosthetic Valves during Ventricular Assist Device Implantation

Abstract Background: An increasing number of patients requiring ventricular assist devices (VAD) have had previous valvular corrections, including valve repair and valve replacement with mechanical or bioprosthetic valves. The operative and peri‐operative management of these patients has been varied. Methods: A retrospective study of VADs between January 1994 and June 2008 revealed 10 patients with previous prosthetic valves requiring management during and after VAD placement. Three patients were supported postcardiotomy after valve surgery. Two patients were supported due to cardiogenic shock postoperatively. Four patients were supported as a bridge to transplantation. One patient was supported as a destination therapy (DT). Results: The mitral, valve was left untreated during VAD implantation regardless of valve repair or replacement. For aortic valves, the mechanical aortic valve was replaced with tissue valve in two patients and left untreated in one case. One patient had tricuspid valve repair previously and was left untouched. All patients with prosthetic valves in aortic, mitral and tricuspid position during VAD support received anticoagulation therapy. There were four deaths, and four went on to transplantation. One patient was weaned from VAD and discharged from the hospital. One patient received HeartMate I as DT. The most common causes of death were multisystem organ failure (MSOF) and sepsis. One patient had a thromboembolic event. Conclusions: The survival rate of 60% is encouraging when compared to overall survival rates. The most common cause of death was MSOF. Patients with prosthetic valves may be safely managed during VAD support. (J Card Surg 2010;25:601‐605)     

Surgical pathology of aortic valve disease. A study based on 602 specimens

A consecutive series of 602 surgically excised aortic valves was evaluated by means of macroscopic and histological study. Pure aortic stenosis was diagnosed in 140 patients, pure incompetence in 254 and combined dysfunction in 208. Of the cases with pure aortic stenosis, 38% were rheumatic, 34% were calcified bicuspid valves and 23% showed dystrophic calcification. Half the patients with pure aortic regurgitation showed aortic root dilatation. Most cases of combined aortic stenosis and regurgitation were the sequelae of rheumatic fever. A male prevalence was detectable in each group (mean male: female ratio = 2.6), and was highest in infective endocarditis and aortic root dilatation. Infective endocarditis was a frequent complication of congenitally bicuspid valves. In conclusion, rheumatic disease is still a frequent cause for surgical replacement of the aortic valve. At least half the explanted aortic valves have degenerative or congenital diseases which are often the site of a superimposed infective endocarditis.     

Pathology of the formalin-treated heterograft porcine aortic valve in the mitral position

The mitral valve was replaced by a pig aortic valve in 33 patients at Groote Schuur Hospital. Eleven of the failed heterograft aortic valves were examined at intervals of from 2 to 32 months after insertion. Fourteen control pig aortic valves were also examined. Electron microscopy was performed on two of the failed heterograft valves and three control pig valves. Failure of the heterograft was due to stretching and deformation of the cusps with resultant valvular incompetence. Stretching of the cusp was a result of reduction in the amount of its collagen content. The elastic tissue appeared little altered. A microscopic layer of fibrin thrombus was present on the surface of 8 of the 11 valves. Only 2 of the 11 valves showed invasion of the graft by immunologically competent cells. No valve showed any sign of infection or calcification. The denatured collagen of the heterograft has a low antigenicity and also, infortunately, a limited durability.     

The Marfan Syndrome: Surgical Technique and Follow-up in 50 Patients

Fifty patients with Marfan's syndrome underwent operation at the National Heart Hospital because of cardiovascular complications. Forty-six had an aneurysm of the ascending aorta, 13 had chronic dissection, and 6 had acute dissection of the aortic wall. Forty-three aortic valves were incompetent, and five were stenotic and incompetent. One mitral valve had minor regurgitation. The Starr-Edwards prosthesis was used in 36 patients, homograft valves in 4, fascia lata valves in 2, and xenograft valves in 6. The ascending aorta was replaced with a Dacron tube in 40 patients and with an aortic homograft in 2. Three patients required Dacron patches over the aneurysm, and 1 patient had plication of the aortic wall.Early mortality totaled 12% (6 patients). Only 1 of these patients died in the last five years. Reoperations for homograft incompetence, periprosthetic leak, and acute dissection of an unreplaced aorta resulted in 1 hospital death (33%). Forty-three patients have been followed for up to 8.5 years (mean, 3.5 years), with 7 late deaths (16.2%). The improvement in recent surgical results with decreased operative mortality supports an aggressive surgical approach to Marfan's syndrome in view of the poor prognosis for the natural history of this disease.     

Implantation of homologous and heterologous aortic valves in prosthetic vascular tubes : An experimental study

Freeze-dried dog and pig aortic valves sutured within tubes of woven Teflon and knitted Dacron have been inserted into the descending aorta of 56 dogs with aortic incompetence. All the valves placed inside woven Teflon were destroyed, with one exception, where six months after insertion the valve was competent and in good condition. Most of the valves in knitted Dacron remained in good condition for up to three months after surgery. The few bad results with knitted Dacron were related to infection or bad haemodynamic conditions. There was no observable difference in behaviour between the homologous and the heterologous valves during the short follow-up of these experiments.     

The Timing of Operation in Valvular Insufficiency

The timing of operation is discussed for aortic, mitral, and combined aortic and mitral insufficiency. The effect of surgical mortality on selection is assessed on the basis of the Green Lane Hospital results for valve replacement in the current cardioplegic era. Particular attention is paid to the effect of the preoperative symptomatic status. The criteria for selection of the patient who is essentially asymptomatic are documented in detail. It is concluded that they differ, depending upon whether there is aortic incompetence, mitral incompetence, or incompetence of both valves. The effect of the type of valve used for replacement on case selection includes an up-to-date assessment of the results achieved with freehand aortic homograft valve replacement.     

Mitral valve replacement with aortic heterografts in humans

The complications associated with the implantation of prosthetic valves and the experimental attempts to graft the mitral valve are described. Because of the disadvantages connected with the use of artificial valves and as the experimental methods of grafting the mitral valve did not prove satisfactory for clinical use, the authors developed a technique for mitral valve replacement using heterologous aortic valves—reinforced by a semirigid Teflon ring—placed above the mitral annulus inside the atrial cavity. The technique of collecting, preparing, and inserting these grafts is described in detail. Using this method, seven patients with mitral incompetence or mitral disease were operated upon between February and April, 1967. One patient died five weeks after the operation from bacterial endocarditis in a period of severe hospital infection with staphylococcus. The other six patients had a very good clinical result immediately after surgery. At the present time they are symptom-free and have normal heart sounds. Clinical and experimental data are discussed concerning the long-term fate of aortic heterografts in the mitral position.     

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.