Aspectos comparativos da localização, distribuição e irrigação do nó atrioventricular em suínos (Sus domesticus) da raça Landrace / Comparatives aspects of localization, distribution and irrigation of theatrioventricular node in pigs (Sus domesticus) of the Landrace race

A análise morfológica buscou verificar a localização do nó e do fascículo atrioventriculares, bem como sua distribuição sob oendocárdio dos ventrículos e descrever as artérias responsáveis pela nutrição do nó, comparando tais aspectos com característicasjá descritas em seres humanos. Foram coletados 30 corações de suínos Landrace, sendo fêmeas com idade entre 2,5 a 3 anos.Inicialmente, 10 corações foram dissecados a fresco, e outros 20 corações foram injetados com solução de neoprene látex,posteriormente fixados em formaldeído a 10% por 72 horas, para então serem dissecados. Foi observado que o nó atrioventricularlocaliza-se na região caudoventral do septo interatrial, próximo à abertura do seio coronário. Também foram observadas quatrotipos de irrigações, sendo que a principal irrigação encontrada nos suínos trata-se do primeiro ramo septal caudal, provenienteda artéria coronária direita. O fascículo atrioventricular atravessou o esqueleto fibroso em direção ao septo interventricular ese dividiu em dois ramos. O ramo direito desceu em direção ao ápice do coração sob o endocárdio, se distribuindo na paredelateral do ventrículo direito e o ramo esquerdo permaneceu único ou se dividiu em dois e três ramos, que se distribuíram naparede do ventrículo esquerdo. A localização e irrigação do nó atrioventricular, assim como a divisão e a distribuição do fascículoatrioventricular são semelhantes à anatomia humana, podendo ser viável a utilização de suínos como modelo experimental emestudos comparativos que investiguem esse sistema.(AU)

Morphological analysis aimed to verify the location of the node and the atrioventricular fasciculus, and its distribution in theendocardium of the ventricles and describe the arteries responsible for nourishing the node, comparing these aspects with features inhumans. Were collected 30 Landrace pig hearts, females, 2.5 to 3 years. Initially, 10 hearts were fresh dissected, and in 20 othershearts were injected with neoprene latex solution, later fixed in 10% formaldehyde for 72 hours, then were dissected. It was observedthat the atrioventricular node was located in the caudoventral region of the atrial septum, near the opening of the coronary sinus. Itwas also observed four types of irrigation, and the main irrigation found in pigs was the first septal branch caudal coming fromthe right coronary artery. The atrioventricular fascicle crossed the fibrous skeleton into the interventricular septum and split into twobranches. The right branch came down towards the apex of the heart under the endocardium, up by distributing itself in the lateralwall of the right ventricle, and the left branch remained single or divided in two and three branches, which are distributed in thewall of the left ventricle. Location and irrigation of the atrioventricular node, as well as the division and distribution of fascicle, aresimilar to Human Anatomy, being viable the use of pigs as an experimental model in comparative studies to investigate this system.(AU)

Conduction system in the swine heart: essential landmarks for gross dissection

Background: The components of the cardiac conduction system (CCS) were discovered almost two centuries and presentedin the diagrammatic forms. This should be due to the diffi culty in distinguishing the CCS from the surrounding cardiactissues and the lack of information concerning the precise landmarks for gross dissection. Furthermore the CCS in pig,the animal regarded as a suitable model for the assessment of catheter based intervention, has not been reported. The aimsof the present study were to demonstrate the gross anatomic architecture of CCS in the swine heart, and to provide thevaluable landmarks for the gross anatomic dissection of the CCS.Materials, Methods & Results: Twenty hearts of adult Large White pigs (Sus Scrofa domesticus) were used. Fifteen heartswere elucidated by gross anatomic dissection. The tissue blocks of the sinoatrial node (SAN) and atrioventricular conduction tissue of the fi ve hearts were prepared for histological investigation by staining with Massons trichrome. It was foundhistologically that the cardiac conduction tissues were clearly distinguishable from the surrounding cardiac myocardiumand connective tissue. Moreover, the histological information also navigated the location and anatomical architecture ofthe CCS which provided essential guideline for gross dissection. The SAN was somewhat spindle in shape which embedded in epicardial connective tissue of the terminal sulcus. In some cases, it was quite diffi cult to identifythe SAN, so thesinoatrial node artery was used as a clue. The AVN was an elliptical shaped which situated in subendocardial tissue atapex of the triangle of Koch on the atrial surface of the central fi brous body. The distal extremity of the AVN extended intothe central fi brous body to form the penetrating bundle of His. At the boundary between the membranous and muscularparts of the interventricular septum, the AV bundle of His divided into the right...(AU)

Conduction system in the swine heart: essential landmarks for gross dissection

Background: The components of the cardiac conduction system (CCS) were discovered almost two centuries and presentedin the diagrammatic forms. This should be due to the diffi culty in distinguishing the CCS from the surrounding cardiactissues and the lack of information concerning the precise landmarks for gross dissection. Furthermore the CCS in pig,the animal regarded as a suitable model for the assessment of catheter based intervention, has not been reported. The aimsof the present study were to demonstrate the gross anatomic architecture of CCS in the swine heart, and to provide thevaluable landmarks for the gross anatomic dissection of the CCS.Materials, Methods & Results: Twenty hearts of adult Large White pigs (Sus Scrofa domesticus) were used. Fifteen heartswere elucidated by gross anatomic dissection. The tissue blocks of the sinoatrial node (SAN) and atrioventricular conduction tissue of the fi ve hearts were prepared for histological investigation by staining with Masson’s trichrome. It was foundhistologically that the cardiac conduction tissues were clearly distinguishable from the surrounding cardiac myocardiumand connective tissue. Moreover, the histological information also navigated the location and anatomical architecture ofthe CCS which provided essential guideline for gross dissection. The SAN was somewhat spindle in shape which embedded in epicardial connective tissue of the terminal sulcus. In some cases, it was quite diffi cult to identifythe SAN, so thesinoatrial node artery was used as a clue. The AVN was an elliptical shaped which situated in subendocardial tissue atapex of the triangle of Koch on the atrial surface of the central fi brous body. The distal extremity of the AVN extended intothe central fi brous body to form the penetrating bundle of His. At the boundary between the membranous and muscularparts of the interventricular septum, the AV bundle of His divided into the right...

Morphology of the atrioventricular junction in Iguana iguana (Reptilia-Iguanidae) / Morfologia da junção atrioventricular em Iguana iguana (Reptilia-Iguanidae)

The atrioventricular junctional area (AVJA), including atrioventricular(AV) node and bundle was investigated in seven hearts of common or green iguana (Iguana iguana) using the light microscopy. Adult animals, both sexes, were captured in the Pantanal, Brazil. All hearts were fixed in buffered formaldehyde 10% (pH 7.2) for 24 hours, embedded in paraplast according to routine methods, and serially cutat 5 ?m thickness. In the Iguana iguana, the AVJA consists of a massof the fibers intermingled with variable amount of connective tissue and blood vessels surrounded by adjacent myocardium and theattachment of the right atrioventricular valve in the fibrous skeleton. By light microscopy, conducting cells of the AV node and bundle canbe distinguished from working cells by their much smaller size, palerstaining reaction and the presence of a sheath of connective tissue.The AV node and bundle and its branches were found to constitutea continuous tract. Histochemically, we found elastic fibers between cells of the conduction, mainly in the AV node. The PAS method reveals absence of glycogen in specialized cells. The fibrous skeleton, mainly the right trigone, showed a well-developed chondroid tissue,made by hyaline like cartilage (binucleated condrocytes included in thebig lacunas and extracellular matrix with fibrillar collagen). In conclusion, the nodal and Purkinje cells in heart iguana presented poorly morphological differentiation comparing mammals and birds, however the skeleton fibrous has a different cartilage kind.(AU)

A área da junção atrioventricular (AJAV), incluindo nó e feixe atrioventriculares foi investigada em sete corações de iguana comum ou verde (Iguana iguana), usando microscopia de luz. Animais adultos, de ambos os sexos, foram capturados no Pantanal, Brasil. Todos os corações foram fixados em formaldeído tamponado 10% (pH 7,2) por 24 horas, incluídos em parapast de acordo com métodos de rotina e seccionados com 5?m de espessura. Na iguana, a AJAV consiste de uma massa de fibras musculares mergulhada em uma quantidade variável de tecido conjuntivo e vasos sangüíneos, rodeada por miocárdio adjacente e aderida à valva atrioventricular direita no esqueleto fibroso. Através da microscopia de luz, células de conduçãodo nó e feixe atrioventriculares podem ser distinguidas das células de trabalho por serem menores, de coloração pálida e pela presença de um envoltório de tecido conjuntivo. O nó AV bem como o feixe AVe seus ramos formam um trato contínuo. Histologicamente, encontramos fibras elásticas entre as células de condução, principalmente no nó AV. O método do PAS revelou a presença de glicogênio nas células especializadas. O esqueleto fibroso, principalmente, o trígono direito, apresentou um tecido condróide bem desenvolvido, constituído de cartilagem semelhante à hialina (condrócitos binucleados inseridos em grandes lacunas e matriz extracelular com colágeno fibrilar). O esqueleto fibroso tem fibrascolágenas e cartilagem semelhante à hialina. Em conclusão, as células nodais e de Purkinje no coração de iguana apresentam pouca diferença morfológica quando comparadas às de mamíferos e aves, contudo o esqueleto fibroso tem um tipo diferente de cartilagem.(AU)