摘要:

AbstractSurgical treatment of truncus arteriosus has been demonstrated to be optimized when approached in early infancy. In the past, the materials available, namely the 12‐mm porcine valve Dacron conduit, restricted the size of the patient in whom early repair could be performed with increasing risk associated with decreasing age and size. The availability of homografts for reconstruction of right ventricular pulmonary artery continuity has allowed repair even in the neonatal period. Two hundred forty‐four patients with truncus arteriosus have been operated on at the University of California San Francisco since 1975. In the past 5 years, 49 have been repaired using homograft reconstruction. The method of repair differs markedly from that of Dacron conduits, and specific points concerning homograft insertion including orientation, method of proximal anastomosis, and sizing are discussed in detail and the difference in insertion from the Dacron bovine heterograft conduit are discus

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00770.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractPulmonary artery sling is an unusual anomaly. The results of surgical therapy have been unsatisfactory in the past because of poor long‐term left pulmonary artery patency and failure to address concomitant primary tracheobronchial stenoses. Refinement of suture materials and microsurgical techniques have allowed earlier surgical treatment of tracheal stenosis and have led to improved pulmonary artery patency rates. Intermediate results of primary one‐stage repair with tracheal resection and left pulmonary artery reimplantation or translocation in early childhood have been promising. It remains to be seen whether late anastomotic tracheal stenosis will be a problem. This constitutes the first report of a case of one‐stage repair with tracheal resection and left pulmonary artery reimplantation in an i

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00771.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractBetween April 1989 and March 1991, 237 CarboMedics bileaf let valve prosthesis carriers (165 aortic and 72 mitral valves, mean age 54.4 years) were studied prospectively with pulsed‐and continuous‐wave Doppler at a mean interval of 11.4 months following surgery in order to establish ranges of normal flow velocities and pressure gradients. Physical examination revealed no signs of prosthetic dysfunction or heart failure. Postoperative left ventricular function as measured by fractional shortening was 37% for aortic valve carriers and 30% for mitral valve carriers (p = N S). Mean peak velocity (± SD) across the aortic valve was 2.6 m/sec (± 0.4) and calculated instantaneous peak pressure gradient ranged from 11 to 58 mmHg (mean 28.1 ± 10.3). It has to be emphasized that occasional patients with normally functioning valve prostheses can show unusual high gradients. Ring diameters between 21 and 27 mm showed no significant difference with regard to flow velocities and pressure gradients, whereas in 19‐mm valves, significantly higher values could be demonstrated. The 123 aortic valve carriers with normal left ventricular function (fractional shortening>25%) showed significantly higher pressure gradients than the 19 patients with reduced left ventricular function (28.6 ± 11.6 mmHg vs 16.2 ± 5.1 mmHg, p<0.05). In the mitral position, the mean of peak velocity (± SD) was 1.7 ± 0.4 m/sec and pressure half‐time was 108 ± 26 msec, representing a calculated valve area between 1.4 to 3.1 cm2(mean orifice size 2.1 ± 0.5 cm2). No significant difference between valves of different sizes was found. Additionally, left ventricular function had no influence on Doppler‐derived hemodynamic measurements. Minimal valvular or paravalvular backflow (extension<1 cm from the prosthesis ring) as indicated by pulsed‐wave or color Doppler was present in 44% of aortic valve and 7% of mitral valve prostheses. Five patients (3%) with aortic valve prostheses and two patients (3%) with mitral valve prostheses demonstrated severe para‐valvular regurgitation without

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00772.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractThere is still no consensus as to how best to categorize and describe interventricular communications. In a series of three reviews, a system will be described showing how the anatomical criteria chosen for categorization will also serve as a guide for surgeons as to the location of the axis responsible for atrioventricular conduction tissue. In this first review, the defects described are not complicated by overriding of arterial or atrioventricular valves and are present in hearts that have basically normal segmental connections, or have some discordant connections (complete transposition or congenitally corrected transposition). The rims of the defect categorize the boundaries to which a surgeon may place a patch. Variations in these rims produce three classes of defect: perimembranous; muscular; and doubly committed and juxtaarterial (subarterial). The second part of the classification recognizes the further variation existing with respect to the component of the morphologically right ventricle into which the defect predominantly empties. Deficient atrioventricular septation can also lead to interventricular shunting in isolation, but the morphology is then quite different from hearts with simple deficiencies of the ventricular septum. We emphasize the abnormal location of the atrioventricular node in hearts with atrioventricular, as opposed to ventricular, septal defects.

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00773.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractSudden cardiac death remains the most common mode of mortality in the United States, accounting for up to 450,000 deaths per year. Survivors of cardiac arrest and patients who have recurrent ventricular tachycardia have a high mortality rate with or without antiarrhythmic therapy. The implantable cardioverter defibrillator (ICD) was introduced in 1980 by Mirowski as a potential treatment for these patients. There are presently over 24,000 implants worldwide and the device has proved to be an effective means of preventing sudden death. The components of an ICD include a generator, defibrillation patches or leads, and pacing/sensing leads. The devices can be implanted with acceptable mortality and morbidity either by median sternotomy, left anterior thoracotomy, subxiphoid, or left subcostal approaches. The long‐term results have been excellent with an actuarial incidence of sudden cardiac death of 3% at 5 years. Improvements in battery and capacitor technology, lead design, and tachycardia recognition, combined with the addition of hemodynamic sensors and a better understanding of the science of defibrillation, should lead to further improvements over the next several years in the IC

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00774.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractTreatment of glutaraldehyde‐fixed pericardium with L‐glutamic acid and storage in bacteriostatic preservatives (paraben) stably antagonizes free, reactive aldehyde groups within the fixed bioprosthetic heart valve tissue. In 63‐day subcutaneous implants in rats, the calcification rate of this treatment (13.3 ± 2 mg calcium/g wt tissue) was markedly reduced as compared to conventionally treated tissue (169 ± 24 mg/g; p<0.05). To test the influence of tissue released toxic aldehdyes on spontaneous endothelial cell ingrowth in vivo, vascular grafts (8‐cm long, 6‐mm diameter) from fixed pericardium treated with L‐glutamic acid were interposed into the carotid arteries in ten sheep. They were compared to grafts from conventionally treated pericardium implanted at the contralateral side. Following 3 months of implantation, planimetry revealed 49%± 20% of the surface of conventionally preserved pericardium to be covered with red thrombus, but only 12%± 5% in L‐glutamic acid treated pericardium (p<0.05). The ultrastructural findings of a closed endothelial cell layer on the graft surface reveals the new technique to be a promising approach towards increased biocompatibility of aldehyde‐fixed biopros

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00775.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractCalcification may be a cause of allograft valve degeneration. To determine whether immunological differences between donor and recipient affect the degree of calcification that occurs, adult Lewis rats received aortic valve allografts transplanted heterotopically into the abdominal aorta. All valves were transplanted immediately after harvest. The valves were not exposed to antibiotics or albumin before insertion. Valve donors were of the Lewis (syngeneic), F344 (weakly allogeneic, RT1 compatible, non‐RT1 incompatible), LBN F1 (moderately allogeneic, one haaplotype identical, one haplotype incompatible at the RT1 and non‐RT1 loci), and Brown Norway (strongly allogeneic, RT1 and non‐RT1 incompatible) strains. Valves were harvested 3–12 weeks following transplantation. Scanning electron microscopy and energy dispersion x‐ray microanalysis were performed on one leaflet of each valve to evaluate calcium content. Calcium content expressed in counts (mean ± standard error) according to donor strain were: Lewis, 1642 ± 233; F344, 4853 ± 1412; LBN F1, 4714 ± 823; and Brown Norway, 4358 ± 835. Significant differences (p<0.05) existed between valves from Lewis donors and those from each other strain. No differences among the other strains were statistically significant. It is concluded that syngeneic valve allografts calcify less than allogeneic grafts. However, the degree of allogenicity did not influence the magnitude of

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00776.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractMitral valve tissue was analyzed in uniaxial tension testing. Rectangular strips were excised from fresh, whole, porcine mitral valve leaflets, with the long axis in the following orientation: perpendicular to the annulus (posterior [PPERP] and anterior [APERP]), parallel to the annulus (posterior [PPAR] and anterior [CAPAR]), and parallel to the annulus and involving chordal insertions (anterior [MAPAR]). Basal and marginal chordae were also tested. These samples were tested in uniaxial tension (INSTRON Model 1000) at deformation rates of 5 and 10 mm/min, the load applied along the long axis of the strip. The specimens were preconditioned by cyclically loading from 0 to 4.0 g for five cycles, and then applying a final 50–9 load. Whole excised porcine mitral valves were previously examined by small angle light scattering, polarized light microscopy, and routine histologic examination in order to ascertain the collagen fiber orientation throughout the valve.1,2Groups tested in uniaxial tension with collagen fibers parallel to the applied stress are significantly stiffer than those with perpendicular fibers (p<0.001). Collagen fiber density is greater in the chordae than in the leaflets, and a corresponding increase in stiffness is demonstrated. This indicates that the mitral valve tissue behaves as a classic fiber reinforced composite, i.e., increasing mechanical stiffness (modulus) is related to density and direction of fibers. This information can be applied to the design of biosynthetic valve substitutes with a similar fiber reinforced composite structur

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00777.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractIn this in vitro study, the growth properties of cultured endothelial cells on conventionally treated pericardial valve material were measured. These data were compared to endothelial cell proliferation on an alternatively treated valve material. This alternative preservation procedure was developed in order to bind free, residual glutaraldehyde in the valve tissue by reaction with L‐glutamic acid. In order to optimize endothelial cell attachment and proliferation, fibronectin and fibrillar collagen type I were tested as surface precoating substances. Cell viability of the seeded cells was evaluated by means of proliferation kinetics, antithrombotic activity, and morphological appearance. Endothelial cell death occurred within the first 2 days after seeding on conventionally treated valve tissue, independent of the type of precoating. On alternatively treated tissue, regular endothelial cell proliferation was observed. Precoating with fibrillar collagen markedly increased endothelial cell attachment and proliferation as compared to fibronectin. Maintenance of antithrombotic activity of the seeded cells was proven by regular release of prostacycli

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00778.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

AbstractA major contributing factor in the degeneration of glutaraldehyde‐treated porcine xenograft bioprostheses is tearing of the valve cusps near their commissural attachment to the supporting stent. We have been examining aortic valves at the micromechanical level, and have developed several sensitive techniques to evaluate the biomechanical changes produced by the glutaraldehyde fixation process. Additionally, we have developed a mathematical modeling technique that simulates valve function during the entire cardiac cycle. Our micromechanical tests have shown that compressive buckling is common to all fixed tissues, occurs at physiological bending curvatures, and is likely to be the primary mode of mechanical failure of bioprosthetic valves. We have also shown that existing glutaraldehyde fixation techniques inhibit the natural internal shearing of the valve cusps, and disable the interaction of the fibrosa and the ventricularis. With our modeling technique, we have shown that flexural stresses are indeed concentrated near the valve commissures, and that appropriate modifications of the supporting stent can reduce flexural deformations. With these new, more revealing techniques at hand, prospective valve designs can be better evaluated prior to large scale animals and clinical testin

ISSN:0886-0440    

DOI:10.1111/j.1540-8191.1992.tb00779.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY