Subcoronary Position Research Articles

Replacement of the aortic valve with a pulmonary autograft: The “Switch” operation

The transfer of the patient's own pulmonary valve to the aortic position developed from our earlier work with aortic homografts. The valve shows no progressive tissue failure and offers the prospect of a permanent valve replacement for young people. Like homografts, the valves can be inserted in the subcoronary position or as a root replacement. In infants and growing children root replacement should be used to benefit from the valve's growth potential.

Viable and nonviable aortic homografts in the subcoronary position: A comparative study

One hundred fifty-five freeze-dried, 63 frozen, and 337 Hanks'-antibiotic solution preserved or nutrient-antibiotic solution preserved homografts used for isolated aortic valve replacement have been followed for 1 to 20 years (mean, 5.3 years), a total of 2, 931 patient-years of follow-up information. Overall survival, valve-related death, primary tissue failure, failure due to surgical technical error, infective endocarditis, and overall eventfree survival have been assented and compared. Overall survival 20 years after operation was 51.6% ± 8.1% with a low incidence of sudden death. The method and length of preservation did not have any effect on the long-term performance or the mode of failure of the homografts. The rate of primary tissue failure was apparently higher with valves preserved in a solution containing calf serum, but the difference was not significant. It is concluded that long-term patient survival and quality of life after aortic valve replacement with a homograft are excellent. The current study, however, could not verify the existence of a significant difference between the three assessed methods of homograft preservation. Furthermore, it could not prove the importance of cellular viability or the existence of clinically significant immunological factors other than the calf serum content of the nutrient medium.

The Fate of Aortic Valve Homografts 12 to 17 Years After Implantation

Results of long-term follow-up of an early cohort of patients receiving aortic valve homografts for aortic stenosis and aortic insufficiency are presented. All patients were operated upon by a single surgeon from 1966 to 1971. Eighty-three patients underwent insertion of 85 homograft aortic valves. Homografts were sterilized with either betapropiolactone (39 valves) or gamma irradiation (41 valves) and were inserted following storage in nutrient medium (16 valves) or after cryopreservation (51 valves). All homograft valves were sutured in the subcoronary position using a freehand technique. There was a 55 percent 15-year actuarial patient survival and a 16 percent 15-year actuarial homograft survival in this cohort. Homograft valve failure occurred gradually allowing the patients to be observed until they developed hemodynamic compromise at which time elective valve replacement was performed.

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.

Aortoventriculoplasty ad modum Konno. Experience with five cases.

We have performed Konno's aortoventriculoplasty in 5 children with congenital valvular aortic stenosis and extreme annular narrowing. There was one hospital death, unrelated to the surgical procedure per se. Bleeding from the stitch holes along the patches immediately after bypass was the sole problem associated with the Konno operation in our 4 surviving patients. Preclotting of the dacron patch or use of calf pericardium did not significantly influence this type of bleeding complication. Konno's aortoventriculoplasty permitted considerable enlargement of the original annular circumference and insertion of a size of prosthesis appropriate for adult life (at least 21 mm tissue diameter) in the 4 survivors. The results were still good 1 to 5 (mean 3) years after surgery. The Konno operation is a safe procedure, which widens the hypoplastic aortic annulus to a possible maximum, relieves most forms of ventricular outflow tract obstruction and maintains the prosthetic valve in anatomic sub-coronary position, so that a left ventricular apical-aortic conduit is not required.

15 years experience with 615 homograft and autograft aortic valve replacements

Homograft valve replacement of the diseased aortic valve with a homologous aortic valve inserted in the sub-coronary position was first performed in July 1962 (Ross 1962). The procedure of transferring the patients autologous pulmonary valve to the aortic position has been used since 1967 (Ross 1967). The long term performance of homograft valves has not been regarded as satisfactory in some centres (Cope-land 1977, Anderson & Hancock 1977) whereas others have shown it to be an excellent valve replacement (Barratt-Boyes, 1977, Bodnar et al 1979). The differing experiences may be the results of alternative methods of sterilization, preservation and surgical insertion. This paper presents information on isolated aortic valve replacements with either homograft or autograft valves over a 15 year period.

In vivo strain measurements of a prosthetic aortic valve

Up to the present, stress forces on prosthetic heart valves have been studied primarily in an in vitro state and have been derived with a fair amount of estimation. Because of the practical and clinical implications, such as forces that may cause fabric wear or material deterioration, we felt that in vivo determination would be worthy of investigation. A microminiature strain gauge was secured to each leg of a non-cloth-covered prosthetic aortic valve and connected to a dual-beam oscilloscope. Strain measurements were first determined in a pulse duplicator with a blood analogue solution and physiological pressures and flow. The valve was also implanted into a dog in the subcoronary position and strain again measured. In vivo strain was found to be approximately 57 per cent of strain on a prosthetic aortic valve, in vitro, under the conditions of this experiment. This represents the first time that strain and force on a prosthetic aortic valve have been determined directly in the intact animal.

Homotransplantation of the aortic valve.

Homotransplantation of heart valves has emerged as a logical consequence to the successful use of vascular homografts (1) (2). After the experimental experience of Lam(3) and Brewin(4), Gordon, Murray in 1956 (5) inserted fresh homograft valves in the descending aorta of 3 patients, and in 1962 Donald Ross implanted an aortic homograft in the subcoronary position for the first time (6).

Storage and function of the canine aortic valve homograft.

Persistent complications result relative to the mechanical nature of cardiac valve replacements. The most successful alternative presently available is the aortic valve homograft. In each of the several centers using homografts, a different method of preparation and storage is used. 1-5 A series of experiments was designed to compare some of these techniques with the fresh aortic valve homograft. To the authors' knowledge this represents the only published series of canine whole-valve homografts transplanted into the subcoronary position. Valve Procurement Donor dogs were anesthetized with sodium methohexital (Brevital Sodium), 5 mg/kg, and exsanguinated from the left carotid artery, the blood being subsequently used for cardiopulmonary bypass. The right chest was then prepared and draped and the heart removed under sterile conditions within an hour of death. The aortic valve was dissected from surrounding tissue and the aorta trimmed to within 3 mm of the valve annulus. All myocardial and fibrous

Pathological changes in human aortic valve homografts.

The pathological changes in 34 homograft valves transplanted to the subcoronary position are described. The valves had been in place up to 30 months and did not show evidence of graft rejection. There was evidence of repopulation of the graft by host cells and endothelialization of the leaflet in one case. There were ten instances of homograft valve failure with valve cusp rupture in eight. In four patients who died 7 to 17 months after implantation, unusual organisms were demonstrable in the thickened calcified valve, although no organisms could be isolated during life. An unidentified fungus was present in two cases and possible mycoplasma in two other cases. The demonstration of homograft infection with unusual organisms suggests that special attention needs to be placed on attempted isolation of organisms in patients with homografts. The relationship of the method of sterilization and storage of homografts used in this series to these infections is unclear.

Calf Aortic Valve Heterograft Replacement for Aortic Valvular Disease

The calf aortic valve heterograft was used to replace the damaged aortic valves in 15 patients. There were two deaths which occurred in the immediate postoperative period. The first seven of the 13 surviving patients were studied six months postoperatively. Results showed that the heterograft valves were working effectively. There was no systolic pressure gradient across the new valve. Clinical competence of the valves has been confirmed by retrograde aortograms. Heart size has decreased in all cases. All the patients have shown marked improvement. It is obviously too short a time to draw any definite conclusions regarding the eventual fate of the implanted heterograft. However, our early clinical and laboratory results have shown that the calf aortic valve heterograft placed in the subcoronary position functions effectively and is well tolerated by the human host. This is most encouraging and it is felt that in view of these results further clinical application of this technique is warranted.

Fresh aortic homografts for multiple valve replacement.

PROSTHETIC valve replacement is associated with persistent late complications related to the mechanical nature of artificial valves. 1-3 These difficulties continue to stimulate the search for better valve substitutes. Fresh aortic valve homografts have been found to be the ideal replacement for use in the subcoronary position. 4 Conversely until very recently no homograft substitute was available for use in the mitral area. 5-7 Our results with Starr-Edwards replacement in multiple valve disease have been reported. 8 The hospital mortality in this series is within a reasonable range. Complications associated with the prolonged use of mechanical valves, however, continue to be significant. The three year morbidity and mortality at our instituion is 20% for mitral, 10% for aortic, and 25% for multiple valve replacement. Nearly all complications are related to thrombosis, embolism, or hemorrhage from anticoagulation. Adaptation of the fresh aortic homograft for use in all intracardiac positions would alleviate

Surgical treatment of valvular heart disease: Part VI. Aortic valve surgery

Aortic valve replacement can be readily accomplished either with a prosthetic valve or a homo- or heterograft placed in the subcoronary position. The operative mortality rate of all procedures is under fifteen per cent. Complications of thrombosis, embolization, and ball variance have plagued the prosthetic ball valve. Fibrosis of valve leaflets, calcification, and late stenosis and insufficiency of the homo- and heterografts have been reported. The ideal aortic valve replacement has not yet been devised, but very satisfactory clinical relief of aortic valve disease is now possible with either prosthetic or grafted valves.

Surgical treatment of valvular heart disease: Part III. Surgical repair of the stenotic mitral valve

Abstract Aortic valve replacement can be readily accomplished either with a prosthetic valve or a homo- or heterograft placed in the subcoronary position. The operative mortality rate of all procedures is under fifteen per cent. Complications of thrombosis, embolization, and ball variance have plagued the prosthetic ball valve. Fibrosis of valve leaflets, calcification, and late stenosis and insufficiency of the homo- and heterografts have been reported. The ideal aortic valve replacement has not yet been devised, but very satisfactory clinical relief of aortic valve disease is now possible with either prosthetic or grafted valves.

Heterotransplantation of the aortic valve into the descending aorta.

HOMOLOGOUS transplantation of the aortic valve into the descending aorta has been successfully performed experimentally and clinically.^1,2Some patients in whom this operation has been done are still alive after many years. Homologous transplantation of the aortic valve into the subcoronary position has also been successfully carried out in a moderately large number of patients with good results up to more than four years postoperatively.^3,4The acquisition of suitable numbers of homologous aortic valves for transplantation could present a problem if this procedure replaced prosthetic replacement as the most favored operation for aortic valve disease. More than 12,000 Starr-Edwards aortic prostheses have been sold by Edwards Laboratories, Inc.; this figure gives an indication of the number of aortic valve operations that have been done. If it could be shown that heterologous valves could be tolerated indefinitely with adequate function, then some of the disadvantages of prostheses might be

TOTAL PROSTHETIC REPLACEMENT OF AORTIC VALVE IN CALVES.

Experimental evaluation of the long-term function and durability of various prostheses is required after total excision and subcoronary replacement of the aortic valve. Only short periods of survival have been reported after total replacement of the aortic valve in the dog. 1,12,27,28,37 Previous experiments in this laboratory demonstrated that the Holstein-Friesian calf could withstand well the extensive surgical procedure necessary for aortic valve replacement and indicated that prolonged survival following these procedures was possible. 23,24 The present study was undertaken to test three types of aortic valve prostheses which were inserted in the subcoronary position in 61 calves. Methods The 61 calves used in this study had a mean age of 23.3 days and a mean weight of 44.6 kg at the time of operation. They were divided into three groups according to the type of prosthesis employed for aortic valve replacement: group 1, 18 calves, bicuspid prostheses constructed of

A METHOD FOR PLACING A TOTAL HOMOLOGOUS AORTIC VALVE IN THE SUBCORONARY POSITION

A METHOD FOR PLACING A TOTAL HOMOLOGOUS AORTIC VALVE IN THE SUBCORONARY POSITION

AORTIC VALVULAR DISEASE

The calf aortic valve heterograft was used to replace the damaged aortlc valves in 15 patients. There were two deaths which occurred in the immediate postoperative period. The first seven of the 13 surviving patients were studied six months postoperatively. Results showed that the heterograft valves were working effectively. There was no systolic pressure gradient across the new valve. Clinical competence of the valves has been confinned by retrograde aortograms. Heart size has decreased in all cases. All the patients have shown marked improvement. It is obviously too short a time to draw any definite conclusions regarding the eventual fate of the implanted heterograft. However, our early clinical and laboratory results have shown that the calf aortlc valve heterograft placed in the subcoronary position functions effectively and Is well tolerated by the human host. This is most encouraging and it is felt that in view of these results further clinical application of this technique Is warranted.