Surgical management of acute aortic root endocarditis with viable homograft: 13-year experience.

OBJECTIVE: Cryopreserved homograft valves have been used for acute infective aortic root endocarditis with great success but it is compounded by its availability in all sizes. The long-term clinical results of geometric mismatched homografts are not well defined and addressed. METHODS: Over a 15-year period (April 1986-June 2001), 816 patients presented with active infective endocarditis. One hundred and eighty-two of the patients aged between 9 and 78 years (mean: 51.0 +/- 1.13 years) consisting of 142 males and 40 females received homograft aortic valves. One hundred and ten patients were in NYHA functional class III and 72 in class IV and in cardiogenic shock. Of the patients, 2.7% suffered from septic embolism. One hundred and twenty-four (68.1%) patients presented with periannular abscesses and 58 (31.9%) with no abscess while 107 native valve (NVE) and 75 prosthetic valve (PVE) endocarditis were diagnosed preoperatively by transesophageal echocardiography (TEE) and confirmed intraoperatively. Freehand subcoronary implantation (FSCI) was used in 106 patients and root replacement in 76 patients. RESULTS: The operative death was 8.5% and for patients in NYHA functional class IV and in cardiogenic shock was 14.5%. Late mortality rate was 7.9%. Patient survival after discharge from hospital at 1 year was 97% and at 10 years was 91%, respectively. Thirty-one (22.1%) patients underwent reoperation after 1.7 years (mean) with two deaths (6.4%). Early (< or = 60 days) and late reinfection rate was 2.7 and 3.6%, respectively. Freedom from reoperation for matched and undersized homografts at 10-13 years was 85 and 55%, respectively. The univariate model identified undersized homograft (P=0.002), FSCI (P=0.09) and reinfection (P=0.0001) as independent risk factors for developing early and late valve dysfunction resulting in reoperation and homograft explant. CONCLUSION: Early aggressive valve replacement with homograft for active infective aortic root endocarditis with periannular abscesses is more successful than delayed last resort surgery. Homografts exhibit excellent clinical performance and durability with a low rate of reinfection, if properly inserted. Undersized homograft is an incremental risk factor for early and late reoperation.

Geometric mismatch between homograft (allograft) and native aortic root: a 14-year clinical experience.

OBJECTIVES: We evaluated the effect of homograft/native aortic root geometric matching and mismatching on valve survival and myocardial remodeling. METHODS: Between January 1, 1987 and March 2000, a total of 292 patients, aged 1.5-78 years (mean, 46.2 years), underwent freehand subcoronary aortic valve (AVR; n=207) and root (ARR; n=85) replacement with matched and mismatched cryopreserved homografts. All patients had pre- and postoperative two-dimensional Doppler echocardiographic studies. Two-hundred and forty-three survivors, excluding children with complete data on sizing, were followed at a total follow-up time of 1269 patient-years. Seventy percent received matched and 30% received mismatched aortic homografts. The homograft valve sizes ranged from 19 to 28 mm. RESULTS: Hospital death for elective first operation was 2.3%, and late death after a mean follow-up of 52 months was 7.9%. The patient survival at 14 years was 92+/-2%. By linear regression analysis, matched homografts were equal to or 1-2 mm less than the native aortic annulus (r(2)=0.73). The valve survival in patients with AVR and ARR was 72+/-4 and 80+/-8% at 14 years, respectively. The freedom from reoperation was 92+/-5, 77+/-4 and 48+/-10% at 14 years for matched, oversized and undersized homografts, respectively (P=0.001). The postoperative cardiac index of patients with 22 and 24 mm homografts was 3.8-4.1 l/m(2), and there was a regression of the left ventricular mass and end-diastolic diameter (P=0.001). CONCLUSIONS: The aortic homograft offers an excellent long-term clinical result. A mismatched homograft is a risk factor for postoperative aortic incompetence, reinfection with pseudoaneurysmal formation and reoperation for the freehand subcoronary implantation technique during the first 7 years of the postoperative period. It is prudent therefore to avoid mismatched homografts and use rather a properly sized stentless xenograft if a root replacement is not indicated.

Comparison of porcine xenografts and homografts for pulmonary valve replacement in children.

BACKGROUND: Due to the limited availability of homografts, different alternatives are used for replacement of the pulmonary valve. This study investigates the value of porcine stentless pulmonary xenografts in pediatric cardiac patients. METHODS: Twenty-three pediatric xenograft (size 10 to 21 mm) recipients were compared with 23 homograft (size 9 to 21 mm) recipients. RESULTS: Hospital mortality was 2 of 23 patients in the xenograft group and 3 of 23 in the homograft group (NS). Six out of 20 xenografts and 1 of 19 homografts were stenotic after 1 year (p = 0.011). Xenograft stenoses were mainly located at the distal anastomosis, while the leaflets were preserved. Homografts showed valvular stenoses and wall calcification. The 1 year freedom from reoperation was 77% in the xenograft and 93% in homograft recipients (NS), and from transcatheter intervention 84% and 100% (p = 0.004), respectively. Transcatheter intervention in 7 xenograft patients and 1 homograft recipient improved stenosis gradients from 65 to 40 mm Hg (mean) in 6 out of 8 patients. Explanted xenografts showed a loss of elastic membranes and proliferating connective tissue scars coated with activated endothelium. CONCLUSIONS: Xenografts demonstrated a higher incidence of supravalvular obstructions, which were possibly due to unfavorable hemodynamics at the distal anastomosis. Histological findings additionally indicated a pronounced immunological response. Interventional angioplasty lowered the rate of reoperation. Thus, the use of xenografts in children can be accepted as a second choice when a homograft is unavailable.

Tricuspid valve dysfunction and surgery after orthotopic cardiac transplantation.

OBJECTIVE: The study examines the prevalence of tricuspid regurgitation and biopsy-induced flail tricuspid leaflets after orthotopic heart transplantation and evaluates the results of the tricuspid valve surgery. METHODS: By a computerized search of the databases 647 of 889 patients who survived heart transplantation for more than 30 days were identified for this study. The primary tool for rejection monitoring in our institution is the daily observation of intramyocardial ECG (IMEG) based on day-by-day changes of the maximal QRS complex amplitude. Endomyocardial biopsy with 45-cm-long sheath bioptome was performed only in doubtful IMEG and echocardiographic data and at times of annual routine heart catheterization. Tricuspid regurgitation was diagnosed clinically and by echocardiography as mild, moderate and severe. Eleven patients received prosthetic valve replacements (four bioprostheses and seven mechanical valves) and six patients underwent valve reconstruction. The choice of xenograft valve was dictated by the condition of renal function. Patient survival and incidence of tricuspid regurgitation and freedom from operation for severe tricuspid regurgitation were analyzed with Kaplan-Meier method. RESULTS: The prevalence of tricuspid regurgitation was 20.1%. Mild and moderate tricuspid regurgitation was seen in 14.5 and 3.1% of the patients, respectively, who were responsive to medical therapy and remained clinically stable in NYHA class I-II. Severe tricuspid regurgitation was seen in 16 (2.5%) patients who presented signs of an acute right heart dysfunction. Tricuspid valve pathology at operation revealed biopsy-induced rupture of the Chordae tendineae at various valve segments mostly the anterior and posterior leaflets. There was one hospital death (<30 day) and five late deaths due to infection, arrhythmia and trauma and no procedural-related or directly cardiac related death. Ten patients (62.5%) are alive at a mean follow-up time of 29.9 months (range 4-81 months) and nine survivors are in NYHA class I-II and one in class III. CONCLUSIONS: Severe tricuspid regurgitation in transplanted hearts is associated mainly with biopsy-induced injury or endocarditis. Other regimes of rejection monitoring may help to eliminate this complication. Apart from our preference of valve repair, the choice of valve substitute may be influenced by the presence or the prospect of chronic renal failure. Heart transplant patients can safely undergo valve surgery with acceptable mortality, low morbidity and excellent intermediate-term clinical results. Mild to moderate functional tricuspid regurgitation is responsive to medical therapy and non-progressive and occur in 17.6% of orthotopic transplanted hearts without having a detrimental effect on the right ventricular performance.

Surgical treatment of active infective aortic valve endocarditis with associated periannular abscess--11 year results.

AIMS: The aim of the study was to evaluate the long-term results of allograft and prosthetic valve replacement in the treatment of infective aortic valve endocarditis with periannular abscess. METHODS: Between March 1988 and March 1996, 65 patients underwent surgery for active aortic valve endocarditis and paravalvular abscess. The indications for surgery were congestive heart failure, systemic emboli and atrioventricular block III. The pre-operative evaluation was performed with transoesophageal echocardiography. Aortic valve replacement was performed with allografts in 47 cases, with mechanical valves in 15, and bioprosthetic valves in three cases. All patients with total ventricular-aortic dehiscence and prosthetic valve endocarditis were treated with allografts. RESULTS: The 30-day mortality rate was 23.5% in the prosthetic group, when compared with 8.5% in the patients treated with allografts. The rate of recurrent valve infections during the 11-year follow-up period was 27.1% in the prosthetic group and 3.2% in the allograft group. The actuarial 11-year survival rate was 82.1% in the allograft group and 64.7% in the prosthetic group. CONCLUSION: Aortic allografts are an effective treatment for infective aortic valve endocarditis with associated periannular abscess. The operative mortality and recurrent infection rates are lower than in the prosthetic group, resulting in a significantly higher survival rate. Diagnosis and surgical management of these cases should be based on pre-operative transoesophageal echocardiography.

Allograft conduit wall calcification in a model of chronic arterial graft rejection.

Early allograft vascular wall degeneration has emerged as a major important complication in young patients. To explain this mechanism, we reviewed studies on explants of allograft valved conduits implanted heterotopically into the infrarenal aorta in inbred rats (LEW; RT1I and CAP-RT1C). The following strain combinations (isografts and allografts) were used: syngeneic, LEW- > LEW, strongly allogeneic, and CAP > LEW (RT1- and non-RT1-incompatible). Second-set skin grafting was performed 3 weeks after the heterotrophic implant to test for immunogenicity and presensitization. The animals (LEW) were sacrificed serially on days 20, 30, 50, and 100 for immunofluorescence and SEM studies. Endothelial disruption was observed on day 30, while valve leaflets appeared normal. Humoral allograft rejection was demonstrated and associated with production of antibodies (IgG) against the endothelial cells and around the smooth muscle cells, and in areas of smooth cell necrosis, through 100 days. Neointimal repopulation by host cells and migrated smooth muscle cells was also observed in both viable and allovital grafts. Allovital grafts demonstrated more disorganized collagen and elastic fibers, as well as calcific degeneration in the media and neointima on day 50; the viable conduits showed such structural changes on day 100. In conclusion, vascular walls of allovital conduits calcified earlier than the viable conduits without discernible calcification of the valves. There is therefore evidence to prove causative relationships between cellular viability, immune response, and fibroproliferative calcific degeneration in allograft vascular conduits.

Risk factors for early degeneration of allografts in pulmonary circulation.

OBJECTIVE: The aim of this study was to define risk factors for early degeneration of allografts in pulmonary circulation and to recommend some guidelines to minimize them. METHODS: Between January 1988 and March 1995, 202 patients with various types of congenital heart disease received cryopreserved allograft conduits for reconstruction of their right ventricular outflow tract. We report on 63 patients receiving allografts ranging from 9-24 mm size within the first 2 years of life. RESULTS: Survivors have been followed for 4-67 months. Survival at 5 years, including hospital mortality, was 66%. Two patients died at reoperation. Of the patients 19.6% (9/46) had early structural deterioration (SD) of their vascular allografts at a mean of 15.2 months after implantation. Seven of these have already been reoperated with allograft exchange. Freedom of reoperation was 66% at 5 years. Infants showed 48% freedom of reoperation at 5 years compared to 90% in the 1-2 years age group, while freedom of SD was 59% in infants at 48 months compared to 87% in the 1-2 years age group. Of allografts with SD in the infant group 66% had an allograft size of < 14 mm. In aortic allografts freedom of SD was 62% compared to 93% in pulmonary allografts. Freedom of allograft wall calcification was 46% at 18 months in all patients. In the statistical analysis, only infant age (P = 0.03) and aortic allograft (P = 0.02) were shown to be significant risk factors for early SD. CONCLUSION: The use of pulmonary allografts, avoidance of relatively short and small conduits of < 14 mm in diameter, might improve the durability of allografts in infants and small children.

Freehand subcoronary aortic valve and aortic root replacement with cryopreserved homografts: intermediate term results.

BACKGROUND AND AIMS OF THE STUDY: The traditional method of aortic valve replacement with a homograft has been free-hand insertion in the subcoronary position. Recently, total root replacement has become increasingly popular. We present our experiences with both methods in this study. MATERIAL AND METHODS: Between January 1, 1987 and March 31, 1996, 208 patients underwent homograft replacement of the aortic valve (free-hand subcoronary technique, n = 147 and root replacement, n = 61). The age of the patients ranged between 1.5 and 78 years with a mean age of 41 years. There were 55 females and 153 males. Ninety-four patients had infected aortic root (with 47 ring abscesses) and 114 patients had sterile aortic roots. In these series, patients with small aortic root, complicated endocarditis, dilated aortic annulus and aneurysm received aortic root replacement. RESULTS: The hospital mortality of patients with non-infected and infected roots was 2.6% and 8.5% respectively making an overall hospital mortality of 5.2%. In patients with free-hand subcoronary valve implantation (AVR) and root replacement (ARR) techniques the hospital mortality was 3.4% and 9.8% respectively. The major risk factor for death was New York Heart Association functional class IV with sepsis. Eight years patient survival in patients with AVR and ARR was 95% +/- 2% and 86% +/- 4% respectively. Freedom from structural deterioration in patients with AVR and ARR was 96.5% +/- 2% and 98% +/- 3% whereas freedom from reoperation was identical 94% +/- 2% and 93% +/- 4% respectively. However, the incidence of reoperation in patients under 40 years of age, particularly in children (< 16 years of age) during the eight years' follow up was 27%. The rate of recurrent endocarditis was 3.6% in ARR patients and development of postoperative pseudoaneurysm formation occurred in 1.4% of AVR patients with endocarditis. CONCLUSION: In conclusion, ARR technique provides low rate of reoperation in the early postoperative period. Cryopreserved homografts in the subcoronary position in adult patients < 40 years of age showed excellent medium term durability and hemodynamic performance providing evidence that long term outcome with a meticulous subcoronary implantation technique is comparable to that with the ARR technique.

Mycotic aortic aneurysms after orthotopic heart transplantation: a three-case report and review of the literature.

Mycotic aortic aneurysm is a rare yet life-threatening complication after orthotopic heart transplantation. This article reviews three cases of mycotic aortic aneurysm in heart transplant recipients developing in the first year after heart transplantation. Excision of the aneurysm and in situ reconstruction of the ascending aorta were performed with a patch of glutaraldehyde-fixed pericardium or cryopreserved aortic allograft material as a patch or conduit replacement. These cases show that early diagnosis by computed tomographic scanning, surgical treatment, high-dose parenteral antibiotics, and close follow-up are essential for successful treatment.

Using aortic allograft material to treat mycotic aneurysms of the thoracic aorta.

BACKGROUND: Although mycotic aneurysms are rare in this age of antibiotics, they nevertheless represent life-threatening lesions of the aortic wall because of their high incidence of rupture and significantly high rate of recurrence. METHODS: Between March 1988 and August 1994, cryopreserved allograft material was used to treat 8 patients (mean age, 62.5 years; range, 47 to 80 years) with mycotic aneurysms of the thoracic aorta at our institution. Two patients had emergency operations; the other operations in 6 patients were elective. The aneurysms were located at the previous cannulation site of the aorta (n = 1) or at the donor/recipient aortic anastomosis (n = 1) in the patients who had heart transplantation, in the ascending aorta in 3 patients with aortic valve endocarditis, in the aortic arch in 2, and in the descending aorta in 1. The operative technique consisted of excision of the mycotic aneurysm followed by allograft patch reconstruction in 5 patients, an allograft composite graft replacement of the ascending aorta in 2 patients with endocarditis, and combined aortic allograft root replacement and allograft patch reconstruction of the ascending aorta in 1 patient. RESULTS: The underlying infections of the aorta were treated successfully in 6 patients. One heart transplant recipient had reoperation because of recurrent mycotic aneurysm after allograft patch reconstruction at the donor/recipient anastomosis. There was one early death involving a patient with Salmonella sp sepsis. CONCLUSIONS: The use of aortic allograft material for repairing mycotic aortic aneurysms is a promising and effective operative concept for managing thoracic aortic infections.

Short-course cyclosporin A therapy for definite allograft valve survival immunosuppression in allograft valve operations.

This study was designed to determine the effect of short-course cyclosporin A therapy (10 mg/kg daily for 14 days) on allograft valve survival across the histocompatibility barriers in the following rat models; (1) syngeneic Lewis to Lewis (herein referred to as autografts), (2) weakly allogeneic AS to Lewis (RT1 compatible, non-RT1-incompatible), and (3) strongly allogeneic CAP to Lewis (RT1 and non-RT1-incompatible). Cyclosporin A-treated and untreated recipient animals (Lewis) received allovital and antibiotic-treated viable allografts implanted into the infrarenal aorta. Second-set skin grafting was performed 3 weeks after heterotopic valve implantation to test for immunogenicity and presensitization. The animals (Lewis) were sacrificed serially on days 20, 50, 100, and 150 for immunofluorescence study using mouse monoclonal antibodies (OX6) directed at class II endothelial surface antigens. The allografts in weakly allogenic strains showed no humoral response under a short course of cyclosporin A. The cyclosporin A-untreated allovital grafts and the viable (antibiotic-treated) valves demonstrated fibrocalcification on the 100th and 150th postoperative days, respectively. In conclusion, it seems that a short course of nontoxic immunosuppression could arrest allograft rejection and thus prevent early degeneration of allografts. Furthermore, antibiotic-treated viable allografts seemed to be more durable than allovital grafts.

Accelerated degeneration of allografts in the first two years of life.

Between January 1988 and May 1994, 53 of 159 patients have received cryopreserved aortic and pulmonary allografts for reconstruction of the pulmonary circuit in the first 2 years of life with body weight ranging from 2.2 to 18 kg (mean, 8.2 +/- 3.4 kg). The implanted allografts ranged in internal diameter from 9 to 23 mm (mean, 16.3 +/- 3.5 mm). Of the 38 survivors who regularly had postoperative echocardiographic examinations 15 (39.5%) underwent cardiac catheterization 1 to 31 months after operation. Allograft dysfunction (gradient > or = 50 mm Hg with or without pulmonary insufficiency) was confirmed in 9 patients leading to reoperation in 5 and valvulo-angioplasty in 4. At 48 months actuarial survival was 64%. In the aortic and pulmonary allografts freedom from wall calcification at 20 months was 19% and 100%, respectively. Freedom from valve dysfunction in patients with aortic and pulmonary allografts was 53% and 88%, respectively; it was 49% in allografts with an internal diameter of 17 mm or smaller. Freedom from reoperation in all patients was 78%. In conclusion, young age, antigenicity (ABO compatibility), and type of allograft seemed to be independent risk factors for early allograft conduit degeneration and late valve dysfunction. Pulmonary allografts seemed to be more resistant to early wall calcification and valve dysfunction than aortic allografts.

Performance of aortic and pulmonary homografts in the right ventricular outflow tract in children.

Cryopreserved homografts have been used at the German Heart Institute Berlin since October 1986. Until 31st May 1994, cryopreserved aortic (AA) or pulmonary (PA) homografts were implanted in the pulmonary position and followed up in 104 patients. The mean age at operation was 5.5 years. The patients were treated with 3-5 mg/kg aspirin daily after the operation for three months. They all had routine echocardiographic evaluation of their homografts, 47 patients were studied by heart catheterization. Excellent functional results of the homograft valves were found in 92 patients (88.5%). Early degeneration of the homograft conduit leading to reoperation was observed in 12 patients. Freedom from wall calcification was 18% in aortic and 78% in pulmonary homografts while freedom from valve dysfunction in aortic and pulmonary homografts at 60 months was 60% and 67%, respectively. Freedom from reoperation was 81% overall, 78% and 84% in patients with aortic and pulmonary homografts respectively (p < 0.05). In conclusion, pulmonary homograft has proved to be more durable than the aortic homograft in the pulmonary position, hence it is the preferential valve for RVOT reconstruction in children.

Clinical report on stentless mitral allografts.

Three patients aged 43, 64 and 54 years (two females and one male) underwent allograft mitral valve replacement including the subvalvular apparatus in 1984 at the Department of Cardiovascular Surgery, University of Kiel. Transpapillary epicardial suture technique was used to support the graft-native papillary muscle union site. Early postoperative course was uneventful in all three patients. There was no early or late postoperative death. Trivial mitral regurgitation was recorded by color Doppler echocardiography but it was not progressive. The regurgitant volume measured at the postoperative catheterization by videodensitometry was less than 10% of the total stroke volume. Two patients were in NYHA class II, nine and 44 months and the third patient was in class III two months after the operation before they suddenly developed severe mitral incompetence which led to emergency reoperations and explantation of their grafts. The early graft failures (two and nine months after insertion) were due to chordal rupture caused by technical error in one and endocarditis in the other, while the late graft failure (44 months after operation) was due to rupture of the scarred graft papillary muscle. No postoperative anticoagulation was given while the homograft mitral valves were in place, and thromboembolic episodes were not observed during that period. All the three patients are alive with prosthetic valves. Although the stentless mitral allograft reinstituted the functional unit of the native mitral valve after replacement and was non-thrombogenic, the graft failure was sudden and unpredictable.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of different preservation and storage conditions on aortic valves: introduction of a quantitative measuring method of the integrity of endothelial cells.

The fate of human allogeneic aortic valves depends mainly on their histological and immunological condition at the time of transplantation. A screening test making novel use of Alcian Blue was used to determine the integrity of endothelial cells as a prerequisite to their function. The dye uptake into the nucleus was measured quantitatively. The test was used to compare the effect of different storage mediums and temperatures (+4 degrees C, -30 degrees C, -80 degrees C, DMSO, FCS, RPMI, antibiotic solution) on aortic valves of rats. The cell integrity decreased with increasing storage time and higher storage temperature. The cryoprotective agent DMSO had no essential effect on the maintenance of cell integrity.

Prognostic importance of viability and a study of a second set allograft valve: an experimental study.

An experimental study of transplantation of first and second set aortic valve allografts in heterotopic infrarenal aortic position in inbred rats with varying histocompatibility is described. On the 20th and 50th postoperative days, there was deposition of donor-specific antibodies on the allograft endothelia of the weakly allogeneic, non-MHC group, as evidenced by immunofluorescence studies, whereas the nonviable grafts showed no identifiable antibodies on their endothelia. The endothelia were mostly lost at day 100; previous focal mononuclear cellular infiltrates disappeared. The ground substances, however, were maintained until the 250th day. In the nonviable allografts, the media was completely acellular on the 50th day with collagen disintegration and changes in ground substance on the 100th day. Loss of endothelia and replacement by fibrin deposits with transient focal cellular infiltrations were the most significant early microscopic findings. Acellularity, fibrous neointima, and leaflet thickening due to varying degrees of fibrosis with changes in ground substance and focal infiltrations of macrophages around degenerated collagenous matrix of aortic valve allografts are the significant late changes. The second set allograft valves showed no difference in the rate or type of healing, but early degeneration while the second set skin grafts underwent accelerated rejection, thus confirming prior sensitization. This finding confirms the weak antigenicity of cardiac valve allografts. Therefore, the use of cardiac valve allografts for secondary valve replacement might be favorable if properly used. Limitation of antigen incompatibility by considering at least the ABO matching and reduction of a recipient's immunological reactivity might be a proper step to achieve a longer survival of viable allografts.

Transplantation of aortic and pulmonary allografts, enhanced viability of endothelial cells by cryopreservation, importance of histocompatibility.

Fresh heart valve allografts were preserved at 4 degrees C for 14 days, cryopreserved and stored for 63 days, and studied for endothelial viability and antigenicity, in order to obtain some information on the immunobiological status of allografts before transplantation. The surgical technique described by Ross for subcoronary position is preferred and briefly outlined. Four explanted incompatible allografts were studied by light and scanning electron microscopy and immunohistochemistry to assess the immunological reactions and tissue changes that occurred between 9 days and 16 weeks postoperatively. Valve leaflet motion and opening velocities were studied by echocardiography postoperatively to establish a baseline with which to distinguish early leaflet degeneration. Distensibility of the aortic annulus was studied postoperatively by supraaortic angiography to justify one of the goals of reconstruction of the aortic root with allografts. Antibiotic preserved allografts at 4 degrees C showed no viable endothelial cells after 8 days while the cryopreserved allografts demonstrated a high rate of viable endothelial cells capable of expressing surface antigens (HLA class I and II). Although the valve explants showed focal mononuclear cell infiltrations with T-lymphocytes, the allografts healed in place. The "classic" findings of rejection could not therefore be demonstrated. In summary, cryopreserved valve allografts, like the fresh, are antigenic. It is therefore recommended to use compatible valve grafts, when possible, which might be a positive step to improve the functional longevity of valve allografts. Immune response after valve allograft transplantation does not cause acute valvular dysfunction but rather chronic tissue changes which might lead to early degeneration of the allograft. The opening velocities of preserved aortic and pulmonary allografts were normal at 3-4 years postoperatively irrespective of histocompatibility. Echocardiography might be a useful tool to detect early degenerative changes of incompatible valve leaflets. The aortic root is distensible after allograft transplantation.

Allogeneous transplantation of the mitral valve. An open question.

To overcome the disadvantages of mechanical valves and bioprostheses, especially in the mitral position, transplantation of an allogeneous mitral valve was performed in 3 patients. One transplant had to be removed 8 weeks postoperatively, most probably due to maladjustment of the anterior leaflet during surgery. The histology of this specimen showed not clear signs of rejection. In 2 patients, echocardiography showed a normal motion pattern of the mitral valves 6 months postoperatively. Regurgitation was less than 10% of the total stroke volume as calculated by videodensitometry. Both patients were in excellent clinical condition. Mitral valve transplantation can be performed with excellent short-term results. Further studies including immunologic monitoring are necessary to evaluate the long-term behavior of the transplant.

Late results of valve xenograft conduits between the right ventricle and the pulmonary arteries in patients with pulmonary atresia and extreme tetralogy of Fallot.

Between 1975 and 1982, valve xenograft conduits were used to establish continuity between the right ventricle and the pulmonary arteries in 28 patients between the ages of 3 to 39 years (mean 14.7 years) with 4 hospital deaths (14%). The indications for operation were pulmonary atresia types I and II in 7, extreme tetralogy of Fallot with hypoplastic pulmonary artery and valvular ring in 10, secondary obliteration of the infundibulum following Waterston shunt in 4, pulmonary valve insufficiency after transannular right ventricular outflow tract patch in 5 and tetralogy of Fallot with anomalous coronary artery in 2. Twenty-one patients (87%) between 9 and 41 years of age (mean 17.4 years) were available for follow-up 1/2 to 8 years after operation. The late death incidence during the follow-up period was 8% (2/24). Postoperative cardiac catheterization, which included right and left ventriculogram and measurements of gradients, was performed in 14 patients 4 months to 6 years after operation. Four patients were in New York Heart Association (NYHA) class 1, 6 in class II and 4 in class III. The other 7 non-catheterized patients were in class II. There were resting peak systolic gradients of 15 to 35 mmHg in 4, 36 to 55 mmHg and more than 55 mmHg across the xenograft valve and the proximal anastomosis in 4 other patients. The right and left ventricular end-diastolic pressures (RVEDP, LVEDP) averaged 18 and 17.5 mmHg, respectively, in 3 patients. The mean ratio of PRV/PLV quotient in NYHA class I group was 0.3, in class II 0.45 to 0.7 and in class III greater than 0.7 (including 2 with residual VSD and pulmonary hypertension). Late densitometric studies for assessing pulmonary valve competence revealed regurgitant fraction of up to 40% of the total stroke volume in the absence of a residual shunt 2 to 4 years after conduit implantation. Three children underwent uneventful surgical replacement of calcified xenograft conduit 1 1/2 to 4 1/2 years after surgery with antibiotic-sterilized valve allograft. Four other patients have residual ventricular septal defects (VSD), 2 of them underwent surgical reclosure while the other 2 patients with pulmonary hypertension still have their residual VSD open.(ABSTRACT TRUNCATED AT 400 WORDS)