Ablação septal com radiofrequência em paciente com obstrução dinâmica na via de saída do ventrículo esquerdo associado a pós operatório de cardiopatia congênita: relato de caso / Septal ablation with radiofrequency in a patient with dynamic obstruction in the left ventricular outflow tract associated with postoperative congenital heart disease: case report

INTRODUÇÃO: A obstrução da via de saída do ventrículo esquerdo (VSVE) é uma condição frequentemente descrita nos casos de cardiomiopatia hipertrófica obstrutiva (CMHO), gerando comprometimento da classe funcional, além de associação com morte súbita. Em pós- -operatório de cardiopatias congênitas com comprometimento da VSVE, podemos observar mecanismo fisiopatológico semelhante aos da CMHO. Atualmente é crescente a aplicação de medidas menos invasivas com objetivo terapêutico, como a ablação endocárdica por radiofrequência (RF) do septo interventricular, que apresenta resultados promissores, sendo uma alternativa à miectomia cirúrgica da VSVE. METODOLOGIA: estudo longitudinal do tipo estudo de caso. RELATO DO CASO: Escolar de 8 anos, portadora de síndrome de Williams, com diagnóstico de base de estenose subvalvar e supravalvar aórtica e ectasia da raiz aórtica, foi submetida aos 6 anos de idade, à ressecção de membrana subaórtica, miectomia da VSVE e ampliação da aorta ascendente. No ano subsequente ao procedimento cirúrgico, evoluiu com sinais de baixo débito cardíaco, associado a achado ecocardiográfico de obstrução dinâmica da VSVE, gerando gradiente sistólico máximo (GSM) inicial de 85mmHg, chegando, até período periprocedimento a 135mmHg. Inicialmente, realizado manejo medicamentoso com betabloqueador, porém paciente manteve sintomatologia a despeito da otimização farmacológica. Desta forma, levando em consideração risco cirúrgico e comportamento anatômico e fisiopatológico, associado a exames de imagem, como tomografia computadorizada com reconstrução tridimensional, optado por realização de procedimento de ablação septal por radiofrequência. Realizadas aplicações de RF em região de maior espessamento. Através da via retroaórtica, foram realizadas aplicações de RF, observando-se modificação do gradiente ecocardiográfico, com GSM final da VSVE de 45 mmHg. Paciente evoluiu com 16 dias após procedimento, com GSM de 13mmHg, ausência de sinais de baixo débito cardíaco e redução significativa da terapia medicamentosa com betabloqueador. Segue atualmente em acompanhamento clínico e ecocardiográfico regular. CONCLUSÕES: O tratamento intervencionista proposto para essa condição parece ser mais seguro. A ablação endocárdica por RF é um procedimento eficaz, seguro em longo prazo, que reduz o tempo de internação hospitalar e morbimortalidade quando comparada à abordagem cirúrgica, com melhora significativa ecocardiográfica e clínica, parecendo ser uma alternativa promissora nas lesões obstrutivas associadas ao pós-operatório de cardiopatias congênitas.

The influence of distance on movement of tabanids (Diptera: Tabanidae) between horses.

Two studies evaluated the potential use of spatial barriers to reduce the mechanical transmission of disease agents by tabanids in the Pantanal region of Brazil. Tabanids at stations separated by four different distances (5, 10, 25, and 50m) were marked. In the first study, tabanids were marked and allowed to feed until engorgement or natural interruption occurred and captured if they transferred to the other horse. A total of 2847 tabanids belonging to nine different species were marked. The percentage of tabanids that moved between horses was 10.5 at 5m, 6.8 at 10m, and 4.6 at 25m. In the second study, flies were marked, feeding was then interrupted, and the flies were released approximately 50cm from the host. A total of 1274 tabanids belonging to five different species were marked. The percentage of flies that moved between horses was 9.7 at 5m, 9.7 at 10m, and 4.6 at 25m. No tabanids transferred between animals separated by 50m in either experiment. The results of this study strongly support the recommendation that segregation of animals effectively prevents the mechanical transmission of pathogens by tabanids.

Seasonality and relative abundance of Tabanidae (Diptera) captured on horses in the Pantanal, Brazil.

Once a month, from June 1992 to May 1993, collections of tabanids on horse were conducted in the Nhecolândia, Pantanal State of Mato Grosso do Sul, Brazil. Tabanid catches using hand nets were conducted from sunrise to sunset at grassland and cerradão (dense savanna) habitats. A total of 3,442 tabanids from 21 species,12 genera, and 3 subfamilies were collected. Although species abundance varied seasonally depending on habitat, no habitat specificity was observed for the most abundant species. In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, while 1,817 (52.8%) tabanids from 17 species were caught in the cerradão. The number of tabanid species varied from 7 during winter (July/August) to 15 in the spring (October). Tabanus importunus (56%) was the most abundant species, followed by T. occidentalis (8.2%), and T. claripennis (8.1%). The tabanid peak, in October, coincided with the beginning of the rainy season. The population peak of most species, including those with higher vector potential, suggests that the rainy season can be considered as the period of potentially higher risk of mechanical transmission of pathogens by tabanids to horses in the region.

Dynamics of Haematobia irritans irritans (Diptera: Muscidae) infestation on Nelore cattle in the Pantanal, Brazil.

From June 1993 to May 1995, horn fly counts were conducted twice a month on untreated Nelore cattle raised extensively in the Pantanal. Horn fly population showed a bimodal fluctuation and peaks were observed every year after the beginning (November/December) and at the end (May/June) of the rainy season, which coincided with mid-late spring and mid-late fall, respectively. Horn flies were present on cattle throughout the year in at least 64% of the animals. Mean horn fly numbers on animals did not exceed 85 flies/cow during peaks and were under 35 flies/cow in most of the remaining periods. The highest infestations (population peaks) were short and dropped suddenly within two weeks. Less than 15% of the animals in both herds could be considered as "fly-susceptible" - showing consistently higher infestations, or "fly-resistant" - showing consistently lower infestations.

Horn fly (Diptera: Muscidae) resistance to organophosphate insecticides.

Insecticidal ear tags impregnated with organophosphate (OP) insecticides were used each year from 1989 to 1998 at Rosepine, LA. Weekly fly counts were conducted to evaluate control efficacy of the treatments, and bioassays were conducted at least twice per year to measure fly susceptibility to OP and pyrethroid insecticides. Between 1989 and 1992, the efficacy of 20% diazinon-impregnated ear tags was reduced from >20 to just 1 week of control. A high risk of control failure was observed when a resistance frequency of approximately 5% was measured in pre-season bioassays. Resistance to diazinon, fenthion, ethion, pirimiphos-methyl, and tetrachlorvinphos was observed. Esterase activity toward alpha-naphthyl acetate was significantly higher in flies collected at Rosepine in 1997 than in flies from a laboratory colony and from a susceptible field population.

Evaluation of a yearly insecticidal ear tag rotation for control of pyrethroid-resistant horn flies (Diptera: Muscidae).

From 1991 to 1997, the yearly alternated use of synergized pyrethroid (lambda-cyhalothrin + piperonyl butoxide) and organophosphate (pirimiphos-methyl) ear tags was evaluated for the control of two pyrethroid-resistant horn fly populations in Louisiana. At each site, weekly fly counts were used to assess product efficacy. Control achieved by synergized pyrethroid ear tag treatments was reduced from 7 to 2 weeks and from 4 to 0 weeks at St. Joseph and Winnsboro, respectively. Control by organophosphate ear tags decreased from 15 to 3 weeks and from 10 to 7 weeks at St. Joseph and Winnsboro, respectively. The rotation of synergized lambda-cyhalothrin and pirimiphos-methyl ear tags did not improve pyrethroid ear tag efficacy or prevent further development of resistance to the pyrethroid or OP compound.