The role of vein grafts in reconstructive head and neck microsurgery

Abstract Objective: Free tissue transfer is widely used for head and neck reconstruction. In certain circumstances, vein grafting is required to elongate free flap pedicles to connect them to appropriate recipient vessels. Because of controversy regarding the use of interposition vein grafts in free tissue reconstruction, this paper reports vein graft indications, techniques, safety, and outcomes for head and neck microvascular surgery. Methods: Twenty-six patients (23 men and 3 women) who underwent interposition vein grafting concurrent with free tissue transfer were included in this study. The most common reason for head and neck reconstruction with vein graft was tumor recurrence, followed by flap salvage. The interposition vein grafts were applied in two manners as temporary arteriovenous (A-V) loop and conduit to extend the length of the free flap for venous drainage. Results: The most common reconstructions were anterolateral thigh flaps (15 cases), followed by vastus lateralis myocutaneous (3 cases) and radial forearm (2 cases) flaps. The common recipient vessels were superior thyroid artery, superficial temporal artery and external jugular vein. The free flap loss rate was 7.7% with vein grafts and 4.9 without vein grafts (p = 0.380). The free flap complication rate was 50.0% and 16.8% in patients with and without vein grafts, respectively (p < 0.001). Radiation therapy, chemotherapy, prior neck dissection, and prior free flap transfer were more common in the vein graft group (all p < 0.001). The hospital stay was significantly longer for the vein graft group than for the non-vein graft group (29.5 vs. 19.0 days; p = 0.001). Conclusion: Overall free flap survival rates of 92.3% and 95.1% in the vein and non-vein graft groups, respectively - indicating the reliability of the vein grafts in challenging head and neck reconstructions, particularly in salvage cases and patients with multiple reconstructions. Level of evidence: Level 3.

Cierre percutáneo de conducto arterioso mediante un asa arteriovenosa en un paciente con síndrome de la cimitarra / Percutaneous closure of ductus arteriosus through an arteriovenous loop in a patient with scimitar syndrome

Resumen: Introducción: El síndrome de la cimitarra consiste en una rara malformación, caracterizada por una conexión anómala parcial de una o ambas venas pulmonares derechas a la vena cava inferior, hipoplasia de pulmón derecho y circulación sistémica desde la aorta descendente. El síndrome de la cimitarra en ocasiones se asocia con otras malformaciones congénitas, entre las que se incluye la persistencia del conducto arterioso (PCA). Caso clínico: Paciente de sexo femenino de cuatro años de edad con síndrome de la cimitarra, variedad ''adulto'', asociado con PCA sintomático. Se realizó exitosamente oclusión del conducto mediante un asa arteriovenosa femoral con un dispositivo Amplatzer® PDA, sin complicaciones. Conclusiones: El manejo del síndrome de la cimitarra es complejo y amerita de un estudio hemodinámico completo para determinar el tratamiento adecuado. La hipertensión arterial pulmonar es un factor de mal pronóstico.

Abstract: Background: Scimitar syndrome consists in a rare malformation characterized by a partial abnormal connection in one or both right pulmonary veins to the inferior vena cava, right lung hypoplasia and systemic circulation from the descending aorta. Scimitar syndrome is occasionally associated to other congenital malformations, such as patent ductus arteriosus (PDA). Case report: We report a 4-year-old patient with ''adult'' variety of scimitar syndrome associated to symptomatic PDA, which was successfully occluded using retrograde guidewire-established femoral arteriovenous loop with an Amplatzer® PDA occluder, without complications. Conclusions: Scimitar syndrome is complex and requires a complete hemodynamic study for the determination of the appropriate treatment. Pulmonary arterial hypertension is a factor associated with poor prognosis.

Prefabrication of Axially Vascularized Bone by Combining β-Tricalciumphosphate, Arteriovenous Loop, and Cell Sheet Technique

The repair of bone defects poses a great challenge for reconstructive surgeons. Although the development of tissue engineering has exhibited promise in replacing damaged bone, the fabrication of large constructs with functional blood vessels remains an obstacle. From the orthopedic surgeon's point of view, the generation of axially vascularized bone, which can anastomose with the recipient vessel, might be a solution to this medical problem. In this study, we aimed to prefabricate an axially vascularized bone by combining a β-TCP scaffold, arteriovenous loop (AVL), and cell sheet in a bioreactor in vivo. Twelve rabbits were randomly allocated into two groups: the experimental group (presence of AVL) and the control group (absence of AVL). The constructs were explanted at 8 weeks postoperatively. The histomorphometric results showed 42.8±5.9% of the bone area in the AVL group and 26.6±3.5% in the control group. Similarly, vessel analysis revealed the average vessel density in the AVL group (12.5±3.3) was significantly more than that in the control group (6.1±1.5, p<0.05). Our research indicated that the combination of a β-TCP scaffold, AVL and cell sheet might engineer vascularized bone. This prefabrication strategy might facilitate clinical translation of bone tissue engineering in reconstructing large bone defects.

Experiencia multicéntrica colombiana durante tres años en el cierre percutáneo de la comunicación interventricular con diferentes dispositivos oclusores: propuesta para la simplicación de la técnica en pacientes seleccionados / Colombian multicentric experience during three years for percutaneous closure of interventricular septal defect with different occluder devices: proposal for technique simplification in selected patients

Objetivos: se describe la experiencia del cierre endovascular de comunicación interventricular realizada durante tres años en diferentes centros de cardiología intervencionista, y se destaca el resultado en un grupo de pacientes seleccionados en quienes dicho procedimiento se efectuó mediante el uso de un dispositivo de última generación diseñado para el cierre de ductus arterioso. Pacientes: entre junio de 2006 hasta octubre de 2009 se sometió un total de 34 pacientes a la técnica de oclusión de comunicación interventricular por vía endovascular. La indicación del procedimiento incluyó sobrecarga de volumen, sobrecarga de presión y volumen, falla cardiaca crónica, prolapso de válvula aórtica con insuficiencia y lesión traumática. La edad promedio fue de 12,9 años y el peso fue de 36 kilos. Se evidenció un predominio del sexo masculino (53 porciento. El promedio de cálculo de flujos demostró Qp/Qs de 1,71 a 1 y el de resistencias vasculares pulmonares fue 1,18 U Wood/m2. Materiales y Métodos: el dispositivo PM VSD Occluder se implantó con la técnica clásica (62,5 porciento) mientras que el dispositivo Duct Occluder II (28,1 porciento) se utilizó con la técnica simplificada propuesta. Se usó anestesia general en 98 porciento de los casos, 60 porciento fueron guiados con fluoroscopia y ecocardiografía transesofágica y 40 porciento con transtorácica. Resultados: el tamaño del defecto varió entre 4 y 12 mm. El 91 porciento de los pacientes tenía un defecto septal aislado. La mediana del tiempo quirúrgico se cuantificó en 56 minutos, siendo mayor en el grupo en el cual se utilizó la técnica clásica (85 min) en comparación con aquel grupo en el que se empleó la técnica simplificada con un promedio de 36 minutos...

Objectives: we describe the experience of the endovascular closure of interventricular communication performed for three years in different centers of interventional cardiology and highlight its result in a group of selected patients in whom such procedure was made by the use of a last generation device designed for the closure of ductus arteriosus. Methodology: between June 2006 and October 2009, a total of 34 patients underwent endovascular occlusion for interventricular septal defect. Indication of this procedure included volume overload, pressure and volume overload, chronic congestive heart failure, aortic valve prolapse with insufficiency and traumatic injury. Mean age was 12,9 years old and mean weight was 36 kg. A prevalence in male gender (53 porciento) was evidenced. Main blood flow calculation showed Qp / Qs of 1.71 to 1 and the pulmonary vascular resistance was 1.18 U Wood/m2. Materials and methods: PM VSD occluder device was implanted with the classic technique (62,5 porciento) while the Duct Occluder II (28,1 porciento) was used with the proposed simplified technique. General anesthesia was used in 98 porciento cases; 60 porciento were guided by fluoroscopy and transesophageal echocardiography and 40 porciento with transthoracic echocardiography. Results: size of the defect varied from 4 to 12 mm. 91 porciento of patients had an isolated septal defect. Mean surgical time was 56 min, being longer in the group in which the classic technique was used (85 min) compared with the group in which the technique used was the simplified one, with a mean duration of 36 min. Mean hospital stay was estimated in 36 hours. Follow up: complete closure was documented in 100 porciento of patients at 30 days. There were three adverse events due to minor complications related to transient rhythm disturbances...

Inducing angiogenesis at tissue engineered bone scaffold by an arteriovenous loop in rabbits / 中华创伤骨科杂志

Objective To compare the effects of 2 vascular carriers, arteriovenous loop and arteri-ovenous bundle, on inducing angiogenesis in coral scaffold of vascularized tissue-engineered bone in animal models.Methods Thirty-six adult male New Zealand rabbits were randomized into 2 even groups.In group A, an arteriovenous loop (AVL) was formed by microsurgical anastomosis at the proximal ends between the femoral poptiteal artery and vein, and placed in the circular side groove of the coral block (6 mm × 8 mm × 10 mm) .In group B, flow-through vessels bundles of both femoral artery and vein were placed in the side grooves of the coral block.All the implants in 2 groups were wrapped by a micro-porous expand-ed-polytetrafluoroethylene (ePTFE) membrane, and fixed subcutaneously by suturing.Evaluation methods included gross morphological observations, histological examinations, India ink perfusion and vascular casting after 2, 4, 6 weeks.The density of blood vessels was analyzed by the statistical software SPSS 10.0.Results All the corals were encased by newly formed fibrovascular tissues in 2 groups.Ink-stained vessels distributed the surfaces and side grooves, and invaded the interspaces of corals.The degree of vascularization increased over the course of experiment.Blood vessel density demonstrated a significant continuous increase between 2 and 6 weeks after implantation in group A.The mean value of blood vessel density in group A (2 weeks 276.60±4.67, 4 weeks 517.20±10.66, 6 weeks 707.00 ±11.87) was significantly higher than in group B (2 weeks 153.60 ±7.16, 4 weeks 269.40±6.80, 6 weeks 279.20±6.53) (P <0.01).Vascular casting showed that in group A, significant blood vessels sprouted from all areas of the loop, espe-cially at the entrance of the arteriovenous pediele where the small tubes were densely interconnected.In group B, however, no blood vessels sprouted from the arteriovenous bundles and only some small vessels grew from the entrance and exit.Conclusions A vascularized coral model can be constructed by inserting an ar-teriovenous loop or an arteriovenous bundle, useful in vascular bone tissue engineering.The former, however, have stronger abilities to induce angiogenesis than the latter.