Native Aortic Tissue Research Articles

Rapid prototyping of compliant human aortic roots for assessment of valved stents

Adequate in-vitro training in valved stents deployment as well as testing of the latter devices requires compliant real-size models of the human aortic root. The casting methods utilized up to now are multi-step, time consuming and complicated. We pursued a goal of building a flexible 3D model in a single-step procedure. We created a precise 3D CAD model of a human aortic root using previously published anatomical and geometrical data and printed it using a novel rapid prototyping system developed by the Fab@Home project. As a material for 3D fabrication we used common house-hold silicone and afterwards dip-coated several models with dispersion silicone one or two times. To assess the production precision we compared the size of the final product with the CAD model. Compliance of the models was measured and compared with native porcine aortic root. Total fabrication time was 3 h and 20 min. Dip-coating one or two times with dispersion silicone if applied took one or two extra days, respectively. The error in dimensions of non-coated aortic root model compared to the CAD design was <3.0% along X, Y-axes and 4.1% along Z-axis. Compliance of a non-coated model as judged by the changes of radius values in the radial direction by 16.39% is significantly different (P<0.001) from native aortic tissue--23.54% at the pressure of 80-100 mmHg. Rapid prototyping of compliant, life-size anatomical models with the Fab@Home 3D printer is feasible--it is very quick compared to previous casting methods.

Treatment of Delayed Retrograde Dissection after Endovascular Stenting of Thoracoabdominal Aortic Aneurysm: Graft-to-Endograft Anastomosis

Endovascular treatment of thoracic aortic aneurysms may be associated with procedure-related early and late complications. We describe the case of a 70-year-old man who developed acute retrograde dissection of the ascending aorta 30 days after endovascular stent grafting of a thoracoabdominal aortic aneurysm and prior revascularization of the left subclavian artery. The ascending aorta and aortic arch were successfully replaced with a Dacron graft; the distal part of the graft was partially anastomosed to the previously placed endograft. Surgical repair of dissections following a thoracic endovascular procedure is reliable with a graft-to-endograft anastomosis when native aortic tissue is not suitable.

Diffusion of Alexa Fluor 488-conjugated dendrimers in rat aortic tissue.

In this study, the distribution of labeled dendrimers in native and aneurysmal rat aortic tissue was examined. Adult male rats underwent infrarenal aorta perfusion with generation 5 (G5) acetylated Alexa Fluor 488-conjugated dendrimers for varying lengths of time. In a second set of experiments, rats underwent aortic elastase perfusion followed by aortic dendrimer perfusion 7 days later. Aortic diameters were measured prior to and postelastase perfusion, and again on the day of harvest. Aortas were harvested 0, 12, or 24 h postperfusion, fixed, and mounted. Native aortas were harvested and viewed as negative controls. Aortic cross-sections were viewed and imaged using confocal microscopy. Dendrimers were quantified (counts/high-powered field). Results were evaluated by repeated measures ANOVA and Student's t-test. We found that in native aortas, dendrimers penetrated the aortic wall in all groups. For all perfusion times, fewer dendrimers were present as time between dendrimer perfusion and aortic harvest increased. Longer perfusion times resulted in increased diffusion of dendrimers throughout the aortic wall. By 24 h, the majority of the dendrimers were through the wall. Dendrimers in aneurysmal aortas, on day 0 postdendrimer perfusion, diffused farther into the aortic wall than controls. In conclusion, this study documents labeled dendrimers delivered intra-arterially to native rat aortas in vivo, and the temporal diffusion of these molecules within the aortic wall. Increasing perfusion time and length of time prior to harvest resulted in continued dendrimer diffusion into the aortic wall. These preliminary data provide a novel mechanism whereby local inhibitory therapy may be delivered locally to aortic tissue.

A cautionary note regarding long-term sequelae of biologic glue

Postoperative hemorrhage remains a significant cause of mortality and morbidity after repair of acute aortic dissection. Accordingly, there has been great interest in the development and application of biologic hemostatic tissue sealants for use during this and other aortic surgical procedures. Among these agents, BioGlue (Cryolife, Inc, Kennesaw, Ga) appears remarkably effective and has rapidly gained wide acceptance. However, because it is composed of 45% (wt/vol) purified bovine albumin and 10% (wt/vol) glutaraldehyde in a 4:1 ratio, we have been concerned that it might not be completely innocuous. We have recently encountered a case of late anastomotic pseudoaneurysm potentially related to the use of BioGlue.

Reconstrução da artéria pulmonar na operação de Jatene

FUNDAMENTOS: A operação de Jatene é a técnica de escolha para correção da transposição das grandes artérias (TGA). A estenose da via de saída do ventrículo direto é a principal complicação encontrada no pós-operatório destas crianças. OBJETIVOS: Avaliar os resultados obtidos em uma série de pacientes portadores de TGA submetidos a operação de Jatene, nos quais a reconstrução da artéria pulmonar (AP) foi realizada com dois remendos de pericárdio autólogo, procurando-se preservar ao máximo a parede aórtica nativa. CASUÍSTICA E MÉTODOS: No período de Janeiro de 1998 a Fevereiro de 2000, foram operadas consecutivamente 52 crianças portadoras de TGA (38 TGA simples/14 TGA + CIV) pela técnica de Jatene, com idade variando de 3 dias a 17 meses (m=30,3 dias). Houve predomínio do sexo masculino (n=30 ou 57,7%) e peso variou de 2,400 kg a 7,400 kg (m=3,377 kg). Todos os pacientes foram operados com CEC em hipotermia moderada, normofluxo e com dose única de cardioplegia sangüínea para proteção miocárdica. O tempo médio de CEC foi de 110,6 min e o tempo médio de pinçamento aórtico de 72,5 min. A transferência coronária foi realizada em "botão", retirando-se o mínimo possível de parede aórtica nativa. A reconstrução foi realizada com dois remendos de pericárdio autólogo, ampliando-se a neo-artéria pulmonar. A avaliação da técnica foi feita através de estudo ecocardiográfico em 20 crianças com seguimento pós-operatório superior a 5 meses(m=12,7 meses). RESULTADOS: Houve 3 (5,8%) óbitos hospitalares, sendo 2 causados por infecção pulmonar (16º e 29º DPO) e 1 por obstrução do tubo endotraqueal (8º DPO). Em todos os casos a técnica foi efetiva para ampliação da neopulmonar, mesmo nos casos de TGA + CIV com importante desproporção dos vasos. O estudo ecocardiográfico pós-operatório apresentou evidências de estenose pulmonar supravalvar em apenas 1 (5%) criança e evidência de crescimento uniforme da AP em todas as outras. CONCLUSÃO: A técnica de reconstrução da AP, preservando-se ao máximo a parede aórtica nativa foi capaz de igualar as artérias mesmo na presença de desproporção significativa, além de propiciar resultados hemodinâmicos satisfatórios em período de até 2 anos de evolução pós-operatória.

Growth characteristics of the aortic arch after the Norwood operation.

We sought to characterize the growth of the reconstructed aortic arch after the Norwood operation (NO). The first stage of surgical palliation of hypoplastic left heart syndrome (HLHS), the NO, includes augmentation of the aortic arch with homograft. Growth characteristics of the reconstructed aortic arch, which is comprised of both native aortic tissue and homograft, have not been characterized. Retrospectively, we examined the serial echocardiograms of 50 patients with HLHS who underwent NO to determine the diameter of the reconstructed transverse arch. Measurements were taken immediately after NO and at two other points (1 to 11 years of age). In addition, the autopsy specimens of 10 other patients with HLHS who underwent NO were examined to determine the contribution of native aortic tissue to the overall size of the reconstructed arch at the time of death (12 to 34 months). The diameter of the transverse aorta increased after NO in all subjects. Its rate of growth paralleled that seen in the normal population, though the reconstructed arch had a significantly larger diameter throughout childhood. Examination of autopsy specimens demonstrated a mean increase in circumference of the native aortic tissue of 0.67 cm (p value <0.01), whereas there was no significant change in homograft circumference. After reconstruction of the aortic arch in HLHS, the diameter of the arch continues to increase throughout childhood, and this increase is due to growth of the native aortic tissue.

New operative method for distal aortopulmonary septal defect

A new technique is described for repairing distal aortopulmonary septal defect with aortic origin of the right pulmonary artery in a 26-day-old neonate. To prevent the narrowing of the proximal right pulmonary artery in the distal aortopulmonary septal defect caused by conventional intraluminal prosthetic patch reconstruction, rerouting of the right pulmonary artery using native aortic wall tissue without artificial material was performed. This method seems to be superior to the conventional method, especially during the neonatal period.