Last twenty-years activity of cardiovascular tissue banking in Barcelona.

The Barcelona Tissue Bank was established from the merge of two previous multi-tissue banks. Potential donors are screened by Donor Center staff and multi-tissue retrieval is performed by specialized own teams. Tissue processing and preservation is performed in clean room facilities by specialised personnel. After quality control of both donor and all tissues results, the heart valves and vascular segments are stored until medical request. The aim of this report is to present the cardiovascular tissue activity and retrospectively evaluate the outcomes of the changes performed in last 20 years. Cardiovascular tissue from 4088 donors was received, specifically 3115 hearts and 2095 vascular segments were processed and evaluated. A total of 48% of the aortic valves, 68% of the pulmonary valves and 75% of the vascular segments were suitable for transplant. The main reason for discarding tissue was macroscopic morphology followed by microbiological results, for both valves and arteries. Altogether, 4360 tissues were distributed for transplantation: 2032 (47%) vascular segments, 1545 (35%) pulmonary valves and 781 (18%) aortic valves. The most common indication for aortic valve surgery was the treatment of endocarditis, while for pulmonary valves, it was congenital malformation reconstruction. Vascular segments were mainly used for reconstruction after ischemia. During this period, a number of changes were made with the goal of enhancing tissue quality, safety and efficacy. These improvements were achieved through the use of a new antibiotic cocktail, increasing of donor age criteria and changing the microbiological control strategy.

Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene.

We evidence by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. We calculate the complex conductivity of graphene under optical pumping and determine the proper conditions for terahertz amplification in single layer graphene. It is shown that amplification in graphene occurs up to room temperature for moderate pump intensities at telecommunication wavelength λ = 1.5 µm. Furthermore, we investigate the coupling between a plasmonic split ring resonator (SRR) metamaterial and optically pumped graphene at a temperature T = 77 K and a pump intensity I = 300 mW/mm(2). We find that the loss of a SRR metamaterial can be compensated by optically stimulated amplification in graphene. Moreover, we show that a hybrid material consisting of asymmetric split-ring resonators and optically pumped graphene can emit coherent THz radiation at minimum output power levels of 60 nW/mm(2).

Tricuspid valve surgery.

INTRODUCTION: The tricuspid valve has been taken as a non-critical valve in terms of acute or late mortality in a number of conditions. Tricuspid functional regurgitation is a cause of late operations with an increased morbidity. A number of techniques have been described and used in clinical practice in the past forty years and include simple suture techniques and the use of support for annuloplasty with the use of different types of prosthetic rings. The experience accumulated over the years indicates that tricuspid annuloplasty is mandatory to improve late results, which are superior, in general, to replacement of the valve. METHODS: The role of echocardiography in defining surgical planning, intraoperative results and follow-up is reviewed as echocardiography is a fundamental tool in cardiac surgery. Surgery for isolated lesions of the tricuspid valve has not received much attention and herein we report the results of the follow-up of a limited series of patients undergoing isolated tricuspid surgery. RESULTS: The correlation between echocardiographic measurements and surgical measurements was confirmed and was helpful at the time of the confirmation of repair (r=0.53). Forty-seven patients (18 repair, 29 replacement) underwent isolated surgery. Results of isolated tricuspid repair seemed to be superior when compared to those of tricuspid replacement. Survival was 20.7% for tricuspid valve replacement (N=18) and 50% for tricuspid valve repair (N=29) (p=0.04). Freedom from reoperation was 94.4±5.4% for repair and 67.3±12.1% for replacement (p= 0.0011). CONCLUSIONS: The tricuspid valve continues to be a surgical challenge.

Fully valley-polarized electron beams in graphene.

We propose a device to break the valley degeneracy in graphene and produce fully valley-polarized currents that can be either split or collimated to a high degree in a experimentally controllable way. The proposal combines two recent seminal ideas: negative refraction and the concept of valleytronics in graphene. The key new ingredient lies in the use of the specular shape of the Fermi surface of the two valleys when a high electronic density is induced by a gate voltage (trigonal warping). By changing the gate voltage in a n-p-n junction of a graphene transistor, the device can be used as a valley beam splitter, where each of the beams belong to a different valley, or as a collimator. The result is demonstrated through an optical analogy with two-dimensional photonic crystals.

CarboMedics Mitroflow pericardial aortic bioprosthesis - performance in patients aged 60 years and older after 15 years.

BACKGROUND: The purpose of this study was to carry out a current assessment of the Mitroflow pericardial bioprosthesis (model 11) according to the durability of the prosthesis after 15 years in patients aged 60 years or older. METHODS: This bioprosthesis was implanted in 161 patients (mean age 69.5 +/- 6.3 years; range 60 - 94 years) undergoing aortic valve replacement (AVR) between 1982 and 1992. There were 84 patients aged 60 - 69 years (mean 64.5 +/- 3.1years) and 77 patients aged 70 years or older (mean 74.8 +/- 4.3 years). Of the total population, concomitant procedures were performed in 63 patients (39.1 %); of these, coronary artery bypass grafting was performed in 39 (24.2 %). RESULTS: Early mortality was 4.8 % (4 patients) in the 60 - 69 year age group and 10.4 % (8) in patients aged 70 years or older ( P = 0.290). Late mortality was 4.5 %/patient-year (35) for those aged 60 - 69 years and 8.1 %/patient-year (49) for those aged 70 years or older ( P = 0.007). Patient survival at 15 years of patients aged 60 - 69 years was 47.6 +/- 6.3 % and of patients aged 70 years or older was 20.9 +/- 5.4 % ( P = 0.003) ( ). Freedom from valve-related mortality for patients in the 60 - 69 year age group was 92.1 +/- 3.5 % at 15 years (0.6 %/patient-year [5]), and in the patient group aged 70 years or older it was 84.4 +/- 5.3 % (1.3 %/patient-year [8]; P = 0.194). Freedom from reoperation for patients in the 60 - 69 year age group was 73.9 +/- 5.0 % (2.6 %/patient-year [20]), and for patients aged 70 years or older it was 91.4 +/- 3.4 % (1.0 %/patient-year [6]; P = 0.029). The structural valve deterioration (SVD) rate for patients in the 60 - 69 year age group was 2.4 %/patient-year (19), and for patients aged 70 years or older it was 1.0 %/patient-year (6) ( P = 0.041). Actuarial freedom from structural valve deterioration at 15 years for patients aged 60 - 69 years was 62.0 +/- 7.3 %, and 80.8 +/- 7.9 % for patients aged 70 years and older ( P = 0.049) (actual freedom 73.9 +/- 5.2 % and 91.4 +/- 3.4 %, respectively). CONCLUSIONS: The Mitroflow pericardial bioprosthesis can still be recommended for aortic valve replacement in patients 70 years and older.

Clinical implications of late mitral valve regurgitation appearance in the follow-up of heart transplantation.

BACKGROUND: Tricuspid regurgitation is frequently observed after orthotopic heart transplantation (OHT), in association with severe pulmonary hypertension. However, the incidence of left-sided valvular disease has not been addressed. AIM: We analyzed the incidence and prognostic implications of left-sided valve disease in 141 patients after OHT. METHODS: Echocardiography was performed with every endomyocardial biopsy during the first year after OHT and every 6 months thereafter. Mitral regurgitation (MR) grade II or III was considered significant. Graft vasculopathy was assessed using coronary angiography. RESULTS: Eight patients (6%) developed significant left-sided valvular disease, namely, MR in 6 (4%) and aortic regurgitation (AR) in 2 (1.4%). The 2 cases with AR were diagnosed the first week after OHT, whereas significant MR was diagnosed at mean follow- up of 34 +/- 6 months. Mean regurgitant orifice and volume were 34 +/- 14 mm2 and 41 +/- 15 mL/beat, respectively. Patients with significant MR had experienced a greater number of acute rejection episodes >or=3A, (1.8 +/- 1.7 vs 0.8 +/- 1.05; P = .02) and were associated with allograft vasculopathy in 83% vs 6% among unaffected patients (P = .0001). Four of 6 patients with significant MR died during follow-up (67%) and 1 of the living patients underwent reparative mitral valve surgery. The probability of survival using Kaplan-Meier curves was significantly lower when patients developed late significant MR (54% vs 76%; P = .0001). CONCLUSIONS: The incidence of significant left-sided valvular disease after OHT was low. MR was associated with a higher degree of previous acute rejection, of graft vasculopathy, and mortality. The presence of moderate or severe MR of late appearance identified a group of OHT patients with poor outcomes.

Imaging properties of photonic crystals.

We observe, by means of finite element calculations, that some photonic crystals produce negative refraction with almost circular isofrequency lines of their band diagram, so that a slab of this structure presents a large degree of isoplanatism and thus can behave like an imaging system. However, it has aberrations on comparison with a model of ideal lossless left-handed material within an effective medium theory. Further, we see that it does not produce subwavelength focusing. We discuss the limitations and requirements for such photonic crystal slabs to yield superresolved images of extended objects.

In vitro evaluation of platelet reactivity toward annuloplasty devices treated with heparin coating: studies under flow conditions.

We have applied an in vitro perfusion model to explore the potential thrombogenicity of polyester annulolasty fabric used in valve repair and to investigate the possible thromboresistance characteristics conferred by a special heparin coating (Duraflotrade mark treatment). Samples of human blood from i) untreated or ii) heparin-coated extracorporeal circuits were recirculated through annular perfusion chambers containing a) untreated or b) treated annuloplasty cloth material. Perfusion experiments were performed at a shear rate of 600 s(-1) for 20 min. Platelet interaction with the material was morphometrically evaluated. In experiments performed with blood from untreated circuits and cloth material, the average cross-sectional area of platelet mass was 615 +/- 135 microm2. Treatment of cloth material with Duraflotrade mark statistically decreased the area of interacting platelets to 319 +/- 101 microm2 (*p < 0.05, n = 10). Blood samples from heparin-coated extracorporeal circuits showed a decrease of total area of platelets (308 +/- 58 microm2 vs 138 +/- 30 microm2, *p < 0.05, n = 9). The combined treatment of Duraflotrade mark in extracorporeal circuits and cloth material caused a more consistent reduction (p < 0.05). The in vitro perfusion experimental model was sensitive to evaluate the thrombogenic potential of Duraflotrade mark treatment. Our results indicate that the heparin coating of cloth material and extracorporeal circuits improves the biocompatibility of the original material and reduces the thrombogenic profile.

[Comparative study of amniotic membrane transplantation, with and without simultaneous application of mitomycin C in conjunctival fornix reconstruction]. / Estudio comparativo entre transplante de membrana amniótica con y sin aplicación simultánea de mitomicina c en reconstrucción de fondo de saco conjuntival.

OBJECTIVE: To describe the results of amniotic membrane (AM) transplantation, using the simultaneous application of 0.02% Mitomycin C (MMC), in conjunctival fornix reconstruction. MATERIAL: We compared two groups of patients: group A, who were treated only with AM and group B, in whom MMC (0.02%) was also applied. Operative technique used: In group A, the surgical procedure involved a careful removal of the cicatricial tissue, followed by AM transplantation. In group B, following the careful removal of the cicatricial tissue, 0.02% MMC was then applied to the surgical field for 60 seconds, and this was followed by extensive irrigation with saline solution. AM transplantation was then performed. We ultimately evaluated the depth of the conjunctival fornix and ocular motility. RESULTS: Group A: eleven eyes of eleven patients were evaluated. Seven had chemical injuries, three had traumatic symblepharon and one had Stevens-Johnson syndrome. In two cases a 7 mm or greater conjunctival fornix depth was observed. In four cases the ocular motility was better than -1. Group B: Twelve eyes of twelve patients were evaluated. Seven had chemical injuries, 2 had traumatic symblepharon and 3 had Stevens-Johnson syndrome. In nine cases a 7 mm or greater conjunctival fornix depth was obtained. In 9 cases the ocular motility restriction was resolved. Poor results of fornix reconstruction, as well as ocular motility, were observed in those patients with autoimmune diseases, irrespective of the treatment used. CONCLUSIONS: The simultaneous combination of AM and MMC results in better conjunctival fornix reconstruction than with the use of AM alone.

Estudio comparativo entre trasplante de membrana amniótica con y sin aplicación simultánea de mitomicina C en reconstrucción de fondo de saco conjuntival / Comparative study of amniotic membrane transplantation, with and without simultaneous application of mitomycin C in conjunctival fornix reconstruction

Objetivo: Describir la eficacia en la reconstrucción de fondos de saco y mejoramiento de la movilidad ocular mediante el uso del transplante de membrana amniótica (MA) y la aplicación transoperatoria de Mitomicina C (MMC) al 0,02%.Material: Se han comparado dos grupos, Grupo A al cual se le realizó liberación de simbléfaron y transplante de MA y Grupo B al que además del transplante se aplicó MMC al 0,02%. Técnica: El tejido conjuntival cicatrizal fue escindido aplicando MMC 0,02% por 1 minuto y lavado exhaustivo posterior a la aplicación. Se colocó MA cubriendo el defecto (grupo A y B). Las variables medidas fueron profundidad de saco conjuntival y movilidad ocular.Resultados: Grupo A once ojos de once pacientes. Siete con quemaduras químicas, tres con simbléfaron traumático y uno con antecedente de Síndrome de Stevens-Johnson. En dos pacientes se obtuvo una profundidad de fondo de saco de 7 mm o mayor. En cuatro pacientes encontramos una limitación a la movilidad ocular menor a –1. Grupo B: Doce ojos de doce pacientes. Siete con quemaduras químicas, dos con simbléfaron traumático y tres con antecedente de síndrome de Stevens-Johnson. En nueve casos se obtuvo profundidad de fondo de saco de 7 mm o mayor. En nueve casos la restricción a la movilidad se eliminó. Los resultados más pobres en ambos grupos se obtuvieron en aquellos con trastornos autoinmunes.Conclusiones: La combinación de MA y MMC demostró resultados más favorables en la reconstrucción de fondos de saco conjuntival que cuando se empleo únicamente MA

Objective: To describe the results of amniotic membrane (AM) transplantation, using the simultaneous application of 0.02% Mitomycin C (MMC), in conjunctival fornix reconstruction. Material: We compared two groups of patients: group A, who were treated only with AM and group B, in whom MMC (0.02%) was also applied. Operative technique used: In group A, the surgical procedure involved a careful removal of the cicatricial tissue, followed by AM transplantation. In group B, following the careful removal of the cicatricial tissue, 0.02% MMC was then applied to the surgical field for 60 seconds, and this was followed by extensive irrigation with saline solution. AM transplantation was then performed. We ultimately evaluated the depth of the conjunctival fornix and ocular motility. Results: Group A: eleven eyes of eleven patients were evaluated. Seven had chemical injuries, three had traumatic symblepharon and one had Stevens-Johnson syndrome. In two cases a 7 mm or greater conjunctival fornix depth was observed. In four cases the ocular motility was better than –1. Group B: Twelve eyes of twelve patients were evaluated. Seven had chemical injuries, 2 had traumatic symblepharon and 3 had Stevens-Johnson syndrome. In nine cases a 7 mm or greater conjunctival fornix depth was obtained. In 9 cases the ocular motility restriction was resolved. Poor results of fornix reconstruction, as well as ocular motility, were observed in those patients with autoimmune diseases, irrespective of the treatment used. Conclusions: The simultaneous combination of AM and MMC results in better conjunctival fornix reconstruction than with the use of AM alone

Transmission study of prisms and slabs of lossy negative index media.

Within an effective medium theory, we numerically study by means of a finite element method the transmission properties of prisms and slabs of media with negative refractive index. The constitutive parameters employed are similar to those of recent experiments that confirmed the existence of negative refraction as well as the focusing property of flat slabs. In this way, we further analyze in detail the influence of diffraction and scattering due to the large wavelength of the radiation in use, and its suppression by employing waveguide configurations with absorbing walls. Also, we address the effects of different amounts of absorption on both the angle of refraction, (for which we derive a new refraction law in prisms), and on the position, resolution and isoplantism of the focus produced by flat slabs.

Cryopreservation alters antigenicity of allografts in a porcine model of transplant vasculopathy.

UNLABELLED: The need for arterial grafts in coronary surgery to complement autologous vessels has generated interest in cryopreservation of small diameter allografts. We evaluated functional and histologic changes occurring in cryopreserved allografts 3 months after porcine femoral artery transplants. METHODS: Twenty recipient and 15 donor pigs included a control group of 16 fresh and 12 cryopreserved nonimplant arteries were used. Fresh (n=5) and cryopreserved (n=5) autografts were implanted to assess cryopreservation effects in the absence of rejection. Fresh allografts with or without treatment with cyclosporine (CsA) (n=6 of 8) and cryopreserved allografts with or without treatment with CsA (n=6 of 10) were performed to study the antigenicity of cryopreserved allografts. Arteries were stained with hematoxylin and eosin, Masson's trichrome, and orcein for morphometric analyses and immunostained to identify endothelial cells, smooth muscle cells, T lymphocytes, and macrophages. RESULTS: Among nonimplant arteries, cryopreservation reduced alpha-actin expression and increased the luminal area. All implanted autografts were patent. Cryopreserved autografts showed reduced alpha-actin expression and developed intimal hyperplasia compared to fresh autografts. Treatment with CsA improved the patency of fresh allografts from 0% to 83% (P <.01) and of cryopreserved allografts from 40% to 100% (P <.05). Cryopreserved allografts showed substantial intimal hyperplasia, and fresh allografts had more T lymphocyte infiltration in the intimal layer with aneurysmal dilatation. CONCLUSIONS: Cryopreservation reduces the deposition of inflammatory cells and prevents the thrombosis or aneurysmal lesions observed in fresh allografts. Therefore, cryopreservation modifies the antigenicity of vascular allografts.

Orbital and periorbital infections.

Infections of the orbit and periorbital tissues are not uncommon. Trauma, skin infections, and sinusitis are frequently the underlying cause. Studies have shown changes in epidemiology and pathogens in the last decade. Although classical manifestations are usually present, atypical cases without specific signs and symptoms may confound the diagnosis. A high index of suspicion, aided by ultrasonography, computed tomography, and magnetic resonance imaging, is frequently required for an accurate diagnosis. Prompt diagnosis and treatment may lead to resolution of the infection, thus avoiding ocular sequelae. Orbital infections may spread into the globe, causing endophthalmitis. Some patients may even need an enucleation or evisceration. New materials and techniques may improve the final result of an anophthalmic socket.

Aortocardiac fistulas complicating infective endocarditis.

This study sought to determine the clinical and echocardiographic features, surgical approach, and outcome of patients with infective endocarditis complicated with aortocardiac fistulas among a series of 346 consecutive cases between 1988 and 1998. Nine patients (2%) were found to have aortocardiac fistulas complicating infective endocarditis caused by highly pyogenic pathogens (4 patients had ruptured abscesses of the right sinus of Valsalva, 3 had fistulous communications from the left coronary sinus, and 1 had a fistulized abscess in the noncoronary sinus). Mortality in these patients was very high (55%), even when surgery was attempted early in the course of the disease and reconstructive procedures were implemented.

Early clinical experience with the On-X prosthetic heart valve.

BACKGROUND AND AIM OF THE STUDY: The study was designed to investigate the clinical performance of the On-X prosthetic heart valve in a multicenter experience. METHODS: Between September 1996 and September 1999, 301 patients (56% males) underwent isolated On-X valve replacement (184 isolated aortic (AVR), 117 isolated mitral (MVR)) at 11 European centers under a standardized protocol. Average age at implant was 60.2 years. Office or hospital follow up was required by the protocol; average follow up on all patients was 11 months. RESULTS: Thirty-day mortality in the study was 2.2% for AVR and 6.0% for MVR, with valve-related mortality of 0.5% for AVR. There were eight late deaths (0.7%/pt-yr AVR and 2.3%/pt-yr MVR). Two of these deaths were sudden, and thus possibly valve-related (one AVR, one MVR). Early total valve-related morbidity was 3.5% for AVR and 2.6% for MVR. In total, 13 thromboembolic events occurred; one early event in AVR resulted in death (0.5%), and one transient early event occurred in MVR (0.9%). There were 11 late events (seven AVR (1.7%/pt-yr) and four MVR (1.8%/pt-yr)), for a two-year freedom from thromboembolism of 96.6% after AVR and 97.1% after MVR. Three late bleeding events occurred, all after AVR (0.7%/pt-yr and 98.9% free at two years). Major paravalvular leaks requiring reoperation occurred on two occasions early (one AVR (0.5%), one MVR (0.8%)) and once late in MVR (0.5%/pt-yr). Late minor, untreated paravalvular leaks occurred in three AVR patients (0.7%/pt-yr) and in one MVR patient (0.5%/pt-yr). Prosthetic endocarditis occurred four times (two AVR (0.5%/pt-yr), two MVR (0.9%/pt-yr)), all within the first 12 months of surgery. Actuarial freedom from all valve-related events at two years was 88.7% for AVR and 88.1% for MVR. NYHA class was improved in 75.8% of AVR patients and 70.6% of MVR patients at two years after surgery. CONCLUSION: These early results indicate that the On-X valve provides satisfactory clinical outcome in the immediate postoperative period, and that the valve is both safe and effective.

[Vancomycin and teicoplanin use as antibiotic prophylaxis in cardiac surgery: pharmacoeconomic study]. / Vancomicina y teicoplanina como profilaxis antibiótica en cirugía cardíaca: estudio farmacoeconómico.

BACKGROUND: To assess the economical impact of vancomycin use versus teicoplanin use as antibiotic prophylaxis for patients undergoing cardiac surgery for valve replacement (VR) and coronary artery by-pass (CABS) procedures. PATIENTS AND METHODS: This is an ancillary cost minimization analysis of a double blinded, parallel groups, randomised clinical trial (RCT), with the main objective of comparing the safety and efficacy of these antibiotics. 500 patients were included in the study; 267 in the CABS group and 233 in the VR group. The CABS patients received 1 g vancomicin or 400 mg teicoplanin, plus 150 mg netilmicin. The VR group received a second dose of each drug after extracorporeal circulation. In order to calculate the costs we considered the direct cost of the drug, the i.v. mix and the administration costs, together with personnel and structure costs. We considered two different situations: the administration of drugs within the surgical room theatre and in the medical ward. RESULTS: The demographic data of both groups were comparable. The frequency of severe adverse drug reactions (ADR) were similar (0.4%) in both groups, as well as the post-operative infection rates (8.6%). Differences were seen in the frequencies of low severity ADRs: 20.4% in the vancomycin group and 1.6% in the teicoplanin group. When the antibiotics were administered in the surgical room, among CABS patients the costs were 8,265 pts. for the teicoplanin group and 12,005 pts. for the vancomycin group; while among VR patients, costs were respectively 11,661 pts. and 14,528 pts. Administration costs of teicoplanin and vancomycin within a medical ward setting, however, the costs were 6,740 pts. and 2,809 pts. for CABS patients, and 5,308 pts. and 10,140 pts. for VR patients, respectively. CONCLUSIONS: The costs of antibiotic prophylaxis among cardiac surgery patients heavily depends on the setting and circumstances of drug administration. The minimization cost analysis indicates that teicoplanin is the most cost-effective option if the drug is administered within the surgical area, while vancomycin is the less costly option when administered within the medical ward. However, if the second option is to be chosen, it is necessary to assure the right plasmatic drug levels of the antibiotic at the beginning of the surgical procedure.

Cardiovascular tissue banking in the non-cadaveric setting: ten-year experience of a university hospital-based bank with active organ donation program.

BACKGROUND AND AIM OF THE STUDY: Today, transplantation of cardiovascular tissues is common practice, and tissue banking has become routine. Consequently, many institutions exist which carry out high-quality tissue banking. METHODS: The Hospital Clinico of the University of Barcelona established its cardiovascular tissue bank in 1989. The bank follows international and national regulations, and functions as a non-profit-making organization. Organ and tissue donors are recruited by the Transplant Coordination unit, which works closely with the Catalonian Organ Transplant Network (OCAT) and the Spanish National Organ Transplantation Network (ONT). The hearts are removed during multi-organ donation and processed using aseptic techniques in a laminar flow hood. Hearts are only accepted from brain-dead multiorgan and non-beating-heart donors. The heart valves are dissected, decontaminated, cryopreserved in specific media and stored in liquid nitrogen at -196 degrees C under strict bacteriological and serological control. RESULTS: Between 1989 and 1999, a series of 1,005 cardiovascular donors from within Spain was identified, from which 840 hearts were processed. After evaluation, 1,099 (65.4%) valves were cryopreserved, and 1,023 (61.5%) given clearance for implantation. In total, 534 aortic, 530 pulmonary, 33 mitral and two tricuspid valves were processed; ultimately 92.8% of aortic and 93.9% of pulmonary valves were accepted for clinical implantation. The rejection rate was 39.1%. Homografts were transported to their destination in dry ice in a cryogenic container. Overall, 608 valves were implanted at our own institution and at hospitals in Barcelona and Europe. Only two cases of complaint were received from implanting surgeons. CONCLUSION: After ten years' experience, the degree of satisfaction of implanting surgeons appears to be adequate. Strict control of the entire tissue banking process has permitted the availability of high-quality homografts for clinical implantation.

Changes in the cooling rate and medium improve the vascular function in cryopreserved porcine femoral arteries.

PURPOSE: The purpose of this study was to design an adequate technique with which to cryopreserve pig femoral arteries and to assess the influence of storage times in vascular function. METHODS: Fifty-two femoral arteries were distributed in seven groups. In group A (control), 10 arteries were studied after harvest; in groups B1 and B2, 19 arteries were suspended in RPMI 1640 plus fetal calf serum plus dimethylsulfoxide and were cryopreserved at 1 degrees C per minute or 0.3 degrees C per minute, respectively. In groups C1 to C4, 23 arteries were suspended in modified Krebs-Henseleit plus dimethylsulfoxide plus sucrose, cryopreserved at 0.7 degrees C per minute, and kept frozen for 1, 15, 60, or 180 days, respectively. After being thawed, arteries were examined for contraction and endothelial-dependent vasodilation (organ bath studies), antithrombotic properties of the endothelial layer(perfusion studies), and vessel structure (electron microscopy). RESULTS: Endothelial cells were present in both cryopreserved and control arteries. The control vessels showed a mean contraction to norepinephrine (10(-7) mol/L) of 13010 +/- 3181 mg. Arteries in groups B1 and B2 did not respond to norepinephrine. Contraction in groups C1 to C4 was as follows: C1, 5354 +/- 1222 mg; C2, 5187 +/- 2672 mg; C3, 6867 +/- 2292 mg; C4, 7000 +/- 2858 mg, which represent 50% of the control values (P <.001). Vasodilation was similar in control (99% +/- 3%) and cryopreserved arteries (C1, 90% +/- 13%; C2, 93% +/- 12%; C3, 89% +/- 15%; C4, 88% +/- 22%). Storage time did not influence vascular function. Platelet interaction was almost absent and similar in all groups. CONCLUSION: A modified cryopreservation technique preserves endothelial function independently of the storage time up to 6 months.

Examination of hemolytic potential with the On-X(R) prosthetic heart valve.

BACKGROUND AND AIM OF THE STUDY: Mechanical valves are known to produce chronic, subclinical hemolysis in most patients. Generally, haptoglobin is reduced to below normal in most patients, while lactate dehydrogenase (LDH) is increased to as much as 200% above the upper normal, sometimes resulting in anemia. The study was designed to investigate the clinical hemolysis of the On-X(R) prosthetic heart valve in a multicenter experience with a standard protocol and a single clinical laboratory. METHODS: Between September 1996 and August 1998, 248 patients underwent isolated valve replacement at 10 European centers. Blood samples were collected from these preoperatively and at 3-6 months and one year postoperatively. All samples were analyzed at a central laboratory, thus assuring poolability of the data. In total, 151 patients were tested at 3-6 months, and 62 at one year. Blood parameters measured were LDH, haptoglobin, hematocrit, total hemoglobin, red cell count and reticulocyte count. Paired analysis was used to compare preoperative baseline values with 3-6-month and one-year values. Data were analyzed with regard to both valve position and size. RESULTS: At 3-6 months and one year after surgery, average values for hematocrit, hemoglobin, red cell count and reticulocyte count were all near the center of the normal range, regardless of valve position or size. Statistically significant increases in red cell count and decreases in reticulocyte count occurred after both aortic valve replacement (AVR) and mitral valve replacement (MVR). These changes were of no clinical importance, but indicate that anemia has not occurred in these patients. At 3-6 months, haptoglobin was reduced to below normal in 86% of both AVR and MVR patients; this also occurred after one year and was statistically significant. Postoperatively, the mean LDH value in AVR was 228 U/l (91% of upper normal, 250 U/l) at 3-6 months, and 246 U/l (98% of upper normal) at one year. In MVR, these LDH values were 271 U/l (108% of upper normal) and 265 U/l (106% of upper normal). CONCLUSIONS: These results indicate that the On-X valve causes lower levels of chronic hemolysis in the immediate postoperative period and up to one year after surgery, especially when compared with reports of LDH elevations up to 200% of upper normal. Hemolytic anemia has not occurred in this patient population.