Peculiaridades da estimulação cardíaca na infância / Peculiarities of cardiac stimulation in infancy

A estimulação cardíaca na população pediátrica possui peculiaridades que merecem destaque. O tamanho dos pacientes, o crescimento somático, as alterações morfológicas das cardiopatias congênitas e o longo período de estimulação são alguns aspectos que devem ser observados nos pacientes que necessitam de implante destes dispositivos. As técnicas de implante epicárdica e endocavitária são opções que devem ser consideradas a cada caso. A escolha pelos implantes epicárdicos esta mais relacionada aos pacientes de pequeno peso, com "shunts" intracavitários ou com anatomia desfavorável. Havendo condições, a opção por implantes endocavitários ou com anatomia desfavorável. Havendo condições, a opção por implantes endocavitários é feita de forma preferencial, principalmente por que esta via apresenta melhores evoluções em longo prazo.

Evaluation of the biological behavior of decellularized pulmonary homografts: an experimental sheep model.

INTRODUCTION: The cryopreserved homograft is a good valve substitute due attributes like excellent hemodynamics, low incidence of thromboembolic events, infection resistance and good mid-term durability. However, progressive homograft degeneration and fibrocalcification may occur, particularly in the childhood and young adults. Their antigenicity triggers an immunological reaction that plays an important role in their degeneration and failure. The decellularization process was proposed to decrease this antigenicity. By the action of detergents and enzymes, this process removes all cellular components from the homograft matrix, diminishing immunogenicity and probably delaying its degeneration. OBJECTIVE: The objective of this experimental and descriptive study is to evaluate the biological and functional behavior of decellularized pulmonary homografts (Decell-H), treated by a sodium dodecil sulfate solution (0.1%), developed in our University (Pontifícia Universidade Católica do Paraná). For the characterization of Decell-H performance, parameters like recellularization, calcification, and echocardiographic data will be analyzed. METHODS: Eight juvenile sheep were submitted to the implantation of the Decell-H sutured into orthotopic position, through a left thoracotomy and with cardiopulmonary bypass support. They were followed-up clinically and by periodical echocardiograms until the explantation, which were performed in different time for every two sheep: seven, 30, 90 and 180 postoperative days. For histological analysis we used Hematoxilin-eosin, Movat and Alizarin-Red staining. RESULTS: The sheep reached their follow-up period in a good clinical state. There was no valve regurgitation or stenonis by the echocardiogram. The animals submitted to the explantation in 90 and 180 days had a significant somatic growth and these Decell-H(s) had a diameter increase, without central valve insufficiency. Histologically, all homografts preserved their extra-cellular matrix organization and were progressively recellularized, without calcification. CONCLUSION: In this experimental model, the Decell-H behaved as an excellent valve substitute.

Avaliação do comportamento biológico de homoenxertos valvares pulmonares descelularizados: estudo experimental em ovinos / Evaluation of the biological behavior of decellularized pulmonary homografts: an experimental sheep model

INTRODUÇÃO: Não havendo um substituto valvar ideal, os homoenxertos criopreservados são considerados uma boa opção, pelo excelente perfil hemodinâmico, baixa incidência de tromboembolismo, resistência a infecções e durabilidade a médio prazo. Porém, estão sujeitos à progressiva degeneração, especialmente em crianças e adultos jovens. Sua antigenicidade desencadeia uma resposta imunológica que contribui para sua degeneração, calcificação e falência. Para diminuir esta antigenicidade, desenvolveu-se o processo de descelularização. Pela ação de detergentes e enzimas, este processo remove os componentes celulares do homoenxerto, diminuindo sua imunogenicidade e, provavelmente, retardando sua degeneração. OBJETIVO: O objetivo deste estudo, experimental e descritivo, é analisar o comportamento histológico e funcional de homoenxertos pulmonares ovinos descelularizados (H-descel) por uma nova solução, composta principalmente de dodecil sulfato de sódio a 0,1 por cento e desenvolvida na PUCPR. Para caracterizar este comportamento, serão avaliados o repovoamento celular, a ocorrência de calcificação e a função valvar ao ecocardiograma. MÉTODOS: A amostra foi constituída de oito ovinos, submetidos ao implante de H-descel em posição ortotópica, através de uma toracotomia esquerda, com auxílio de circulação extracorpórea. Os animais foram acompanhados clinicamente e por ecocardiogramas periódicos até o explante, realizados em prazos predefinidos para cada dois animais: sete, 30, 90 e 180 dias. A análise histológica foi realizada por colorações Hematoxilina-eosina, Pentacrômio de Movat e Alizarina Red. RESULTADOS: Todos os animais sobreviveram ao procedimento e atingiram seus períodos de seguimento. Não houve insuficiência ou estenose destes enxertos ao ecocardiograma. Os animais submetidos aos explantes em 90 e 180 dias tiveram significativos ganhos ponderais e estes H-descel aumentaram de diâmetro, sem desenvolver insuficiência. À histologia, todos mantiveram a organização de sua matriz extracelular, foram progressivamente repovoados e não apresentaram calcificação. CONCLUSÃO: Neste modelo experimental, os H-descel mostraram-se excelentes substitutos valvares a médio prazo.

INTRODUCTION: The cryopreserved homograft is a good valve substitute due attributes like excellent hemodynamics, low incidence of thromboembolic events, infection resistance and good mid-term durability. However, progressive homograft degeneration and fibrocalcification may occur, particularly in the childhood and young adults. Their antigenicity triggers an immunological reaction that plays an important role in their degeneration and failure. The decellularization process was proposed to decrease this antigenicity. By the action of detergents and enzymes, this process removes all cellular components from the homograft matrix, diminishing immunogenicity and probably delaying its degeneration. OBJECTIVE: The objective of this experimental and descriptive study is to evaluate the biological and functional behavior of decellularized pulmonary homografts (Decell-H), treated by a sodium dodecil sulfate solution (0.1 percent), developed in our University (Pontifícia Universidade Católica do Paraná). For the characterization of Decell-H performance, parameters like recellularization, calcification, and echocardiographic data will be analyzed. METHODS: Eight juvenile sheep were submitted to the implantation of the Decell-H sutured into orthotopic position, through a left thoracotomy and with cardiopulmonary bypass support. They were followed-up clinically and by periodical echocardiograms until the explantation, which were performed in different time for every two sheep: seven, 30, 90 and 180 postoperative days. For histological analysis we used Hematoxilin-eosin, Movat and Alizarin-Red staining. RESULTS: The sheep reached their follow-up period in a good clinical state. There was no valve regurgitation or stenonis by the echocardiogram. The animals submitted to the explantation in 90 and 180 days had a significant somatic growth and these Decell-H(s) had a diameter increase, without central valve insufficiency. Histologically, all homografts preserved their extra-cellular matrix organization and were progressively recellularized, without calcification. CONCLUSION: In this experimental model, the Decell-H behaved as an excellent valve substitute.

The use and midium-term evaluation of decellularized allograft cusp in the surgical treatment of the tetralogy of fallot.

OBJECTIVE: To describe the technique of implantation and to show the echocardiographic follow-up of the decellularized cusps allografts used in patients with tetralogy of fallot. METHODS: Fifteen patients underwent this implantation between March 2005 and August 2007 and they were clinically followed-up. An echocardiogram was performed to evaluate the morphofunctional result of the allografts. RESULTS: The mean follow-up was 12.7 months (1-25 months). The echocardiography results showed that pulmonary insufficiency was mild in nine (60%) patients, moderate in three (20%) patients, and severe in three (20%) patients. The results also showed that the systolic right ventricle function was normal in 13 (86.7%) and that there was mild dysfunction in two (13.3%). Eleven (73.4%) patients did not present any gradient in the right ventricular outflow tract and four (26.6%) presented mild stenosis. The mobility of the cusps were normal in all cases and there was no thickness larger than 1.5 mm. There was no calcification; 14 patients (93.3%) presented Z score between -1 and 0,7 and one patient presented dilated pulmonary annulus with a Z score of + 2.5. CONCLUSION: In midium-term follow-up, the decellularized allograft seemed to be a good option for right ventricle outflow tract enlargement in patients underwent tetralogy of Fallot.

Emprego e avaliação em médio prazo da cúspide de homoenxerto decelularizado na correção da tetralogia de Fallot / The use and midium-term evaluation of decellularized allograft cusp in the surgical treatment of the tetralogy of Fallot

OBJETIVO: Descrever a técnica de preparo e a evolução ecocardiográfica das cúspides de homoenxerto decelularizado utilizadas em pacientes com tetralogia de Fallot. MÉTODOS: No período de março de 2005 a agosto de 2007, 15 pacientes foram submetidos ao implante deste tipo de enxerto e foram acompanhados clinicamente e com ecocardiograma para avaliar o resultado morfofuncional dos enxertos. RESULTADOS: O acompanhamento médio foi de 12,7 meses (1-25 meses). A análise ecocardiográfica em médio prazo revelou: insuficiência pulmonar leve em nove (60 por cento) pacientes, moderada em três (20 por cento) e importante em três (20 por cento); a função sistólica do ventrículo direito esteve preservada em 13 (86,7 por cento) pacientes e com disfunção leve em dois (13,3 por cento); 11 (73,4 por cento) pacientes não apresentaram gradientes na via de saída do ventrículo direito (VD), e em quatro (26,6 por cento) pacientes evidenciou-se a presença de estenose leve; a mobilidade da cúspide foi normal em todos os pacientes; não houve espessamento maior de 1,5mm nas cúspides analisadas; não se detectou nenhuma calcificação nas cúspides. Catorze (93,3 por cento) pacientes apresentaram Z score entre -1 e 0,7 e um (6,7 por cento) paciente apresentou anel pulmonar com Z score de + 2,5. CONCLUSÃO: O retalho de homoenxerto decelularizado parece ser uma boa opção para a ampliação da via de saída do VD nos pacientes submetidos à correção total da tetralogia de Fallot em médio prazo.

OBJECTIVE: To describe the technique of implantation and to show the echocardiographic follow-up of the decellularized cusps allografts used in patients with tetralogy of Fallot. METHODS: Fifteen patients underwent this implantation between March 2005 and August 2007 and they were clinically followed-up. An echocardiogram was performed to evaluate the morphofunctional result of the allografts. RESULTS: The mean follow-up was 12.7 months (1-25 months). The echocardiography results showed that pulmonary insufficiency was mild in nine (60 percent) patients, moderate in three (20 percent) patients, and severe in three (20 percent) patients. The results also showed that the systolic right ventricle function was normal in 13 (86.7 percent) and that there was mild dysfunction in two (13.3 percent). Eleven (73.4 percent) patients did not present any gradient in the right ventricular outflow tract and four (26.6 percent) presented mild stenosis. The mobility of the cusps were normal in all cases and there was no thickness larger than 1,5mm. There was no calcification; 14 patients (93,3 percent) presented Z score between -1 and 0,7 and one patient presented dilated pulmonary annulus with a Z score of + 2.5. CONCLUSION: In midium-term follow-up, the decellularized allograft seemed to be a good option for right ventricle outflow tract enlargement in patients underwent tetralogy of Fallot.