3D models of the cardiac conduction system in healthy neonatal human hearts.

Iatrogenic damage to the cardiac conduction system (CCS) remains a significant risk during congenital heart surgery. Current surgical best practice involves using superficial anatomical landmarks to locate and avoid damaging the CCS. Prior work indicates inherent variability in the anatomy of the CCS and supporting tissues. This study introduces high-resolution, 3D models of the CCS in normal pediatric human hearts to evaluate variability in the nodes and surrounding structures. Human pediatric hearts were obtained with an average donor age of 2.7 days. A pipeline was developed to excise, section, stain, and image atrioventricular (AVN) and sinus nodal (SN) tissue regions. A convolutional neural network was trained to enable precise multi-class segmentation of whole-slide images, which were subsequently used to generate high- resolution 3D tissue models. Nodal tissue region models were created. All models (10 AVN, 8 SN) contain tissue composition of neural tissue, vasculature, and nodal tissues at micrometer resolution. We describe novel nodal anatomical variations. We found that the depth of the His bundle in females was on average 304 µm shallower than those of male patients. These models provide surgeons with insight into the heterogeneity of the nodal regions and the intricate relationships between the CCS and surrounding structures.

The anatomy of the atrioventricular nodal artery: A meta-analysis with implications for cardiothoracic surgery and ablation procedures.

The objective of the present meta-analysis was to evaluate recent and applicable data regarding the location and variation of the atrioventricular nodal artery (AVNA) in relation to adjacent structures. In order to minimize postoperative risks and maintain physiological anastomosis for proper cardiac function, understanding such possible variations of vascularization of the AV node is of immense importance prior to cardiothoracic surgery as well as ablations. In order to perform this meta-analysis, a systematic search was conducted in which all articles regarding, or at least mentioning, the anatomy of the AVNA was searched. In general, the results were based on 3919 patients. AVNA was found to originate only from the RCA in 82.41% (95% CI: 79.46%-85.18%). The pooled prevalence of AVNA originating only from LCA was found to be 15.25% (95% CI: 12.71%-17.97%). The mean length of AVNA was found to be 22.64 mm (SE = 1.60). The mean maximal diameter of AVNA at its origin was found to be 1.40 mm (SE = 0.14). In conclusion, we believe that this is the most accurate and up-to-date study regarding the highly variable anatomy of the AVNA. The AVNA was found to originate most commonly from the RCA (82.41%). Furthermore, the AVNA was found to most commonly have no (52.46%) or only one branch (33.74%). It is hoped that the results of the present meta-analysis will be helpful for physicians performing cardiothoracic or ablation procedures.

Morphological variations of the conduction system in the atrioventricular zone and its clinical relationship in different species.

Atrioventricular node is responsible for delaying the passage of the electrical impulse to ventricles in order to protect them from fast depolarizations coming from the atria. The importance of this study is to identify the morphological variations of the components of atrioventricular zone that affect the conduction system and its clinical relationship in different species of mammals. We analyzed ten human hearts, nine from horses, eight from pigs, and five from dogs without a clinical history of cardiac pathologies. Histological section thickness of 5 µm were obtained with a microtome and stained with hematoxylin-eosin and Masson's trichrome. We observed both an increase in collagen fibers and a decrease in the size of P cells (nodal pacemaker cells) within the atrioventricular node in dogs, horses and pigs in cases that presented cartilage in fibrous body. The percentage of fundamental substance in atrioventricular node was significantly higher in dogs and the percentage of collagen fibers was higher in pigs, both than in humans. The presence of cartilaginous metaplasia in cardiac fibrous skeleton from different species decreases the size of atrioventricular node and its cells and increases the percentage of collagen fibers within the node, which can reduce the transmission of the electrical impulse to ventricles and therefore predispose to the presentation of ventricular arrhythmias. Morphometric analysis has allowed us to objectively quantify each of the components of AV node and compare them in the different species.

Localization of the sinoatrial and atrioventricular nodal region in neonatal and juvenile ovine hearts.

Localization of the components of the cardiac conduction system (CCS) is essential for many therapeutic procedures in cardiac surgery and interventional cardiology. While histological studies provided fundamental insights into CCS localization, this information is incomplete and difficult to translate to aid in intraprocedural localization. To advance our understanding of CCS localization, we set out to establish a framework for quantifying nodal region morphology. Using this framework, we quantitatively analyzed the sinoatrial node (SAN) and atrioventricular node (AVN) in ovine with postmenstrual age ranging from 4.4 to 58.3 months. In particular, we studied the SAN and AVN in relation to the epicardial and endocardial surfaces, respectively. Using anatomical landmarks, we excised the nodes and adjacent tissues, sectioned those at a thickness of 4 µm at 100 µm intervals, and applied Masson's trichrome stain to the sections. These sections were then imaged, segmented to identify nodal tissue, and analyzed to quantify nodal depth and superficial tissue composition. The minimal SAN depth ranged between 20 and 926 µm. AVN minimal depth ranged between 59 and 1192 µm in the AVN extension region, 49 and 980 µm for the compact node, and 148 and 888 µm for the transition to His Bundle region. Using a logarithmic regression model, we found that minimal depth increased logarithmically with age for the AVN (R2 = 0.818, P = 0.002). Also, the myocardial overlay of the AVN was heterogeneous within different regions and decreased with increasing age. Age associated alterations of SAN minimal depth were insignificant. Our study presents examples of characteristic tissue patterns superficial to the AVN and within the SAN. We suggest that the presented framework provides quantitative information for CCS localization. Our studies indicate that procedural methods and localization approaches in regions near the AVN should account for the age of patients in cardiac surgery and interventional cardiology.

Morphological study of the atrioventricular conduction system and Purkinje fibers in yak.

We studied the morphology of the atrioventricular conduction system (AVCS) and Purkinje fibers of the yak. Light and transmission electron microscopy were used to study the histological features of AVCS. The distributional characteristics of the His-bundle, the left bundle branch (LBB), right bundle branch (RBB), and Purkinje fiber network of yak hearts were examined using gross dissection, ink injection, and ABS casting. The results showed that the atrioventricular node (AVN) of yak located in the right side of interatrial septum and had a flattened ovoid shape. The AVN of yak is composed of the slender, interweaving cells formed almost entirely of the transitional cells (T-cells). The His-bundle extended from the AVN, and split into left LBB and RBB at the crest of the interventricular septum. The LBB descended along the left side of interventricular septum. At approximately the upper 1/3 of the interventricular septum, the LBB typically divided into three branches. The RBB ran under the endocardium of the right side of interventricular septum, and extended to the base of septal papillary muscle, passed into the moderator band, crossed the right ventricular cavity to reach the base of anterior papillary muscle, and divided into four fascicles under the subendocardial layer. The Purkinje fibers in the ventricle formed a complex spatial network. The distributional and cellular component characteristics of the AVCS and Purkinje fibers ensured normal cardiac function.

Identification of nodal tissue in the living heart using rapid scanning fiber-optics confocal microscopy and extracellular fluorophores.

BACKGROUND: Risks associated with pediatric reconstructive heart surgery include injury of the sinoatrial node (SAN) and atrioventricular node (AVN), requiring cardiac rhythm management using implantable pacemakers. These injuries are the result of difficulties in identifying nodal tissues intraoperatively. Here we describe an approach based on confocal microscopy and extracellular fluorophores to quantify tissue microstructure and identify nodal tissue. METHODS AND RESULTS: Using conventional 3-dimensional confocal microscopy we investigated the microstructural arrangement of SAN, AVN, and atrial working myocardium (AWM) in fixed rat heart. AWM exhibited a regular striated arrangement of the extracellular space. In contrast, SAN and AVN had an irregular, reticulated arrangement. AWM, SAN, and AVN tissues were beneath a thin surface layer of tissue that did not obstruct confocal microscopic imaging. Subsequently, we imaged tissues in living rat hearts with real-time fiber-optics confocal microscopy. Fiber-optics confocal microscopy images resembled images acquired with conventional confocal microscopy. We investigated spatial regularity of tissue microstructure from Fourier analysis and second-order image moments. Fourier analysis of fiber-optics confocal microscopy images showed that the spatial regularity of AWM was greater than that of nodal tissues (37.5 ± 5.0% versus 24.3 ± 3.9% for SAN and 23.8 ± 3.7% for AVN; P<0.05). Similar differences of spatial regularities were revealed from second-order image moments (50.0 ± 7.3% for AWM versus 29.3 ± 6.7% for SAN and 27.3 ± 5.5% for AVN; P<0.05). CONCLUSIONS: The study demonstrates feasibility of identifying nodal tissue in living heart using extracellular fluorophores and fiber-optics confocal microscopy. Application of the approach in pediatric reconstructive heart surgery may reduce risks of injuring nodal tissues.

Relaciones biométricas del anillo atrioventricular izquierdo y las arterias coronarias en el hombre / Biometric relationships between the left atrioventricular ring and the coronary arteries in man

La relación de las arterias coronarias con los anillos atrioventriculares se torna importante en casos de reemplazo o plastía de la valva correspondiente. La proximidad de la rama circunfleja de la arteria coronaria izquierda al anillo atrioventricular izquierdo, a nivel de la comisura anterior, ha traído complicaciones quirúrgicas, en algunos casos con resultados fatales. Basado en lo anterior, estudiamos las relaciones biométricas entre las arterias coronarias y el anillo atrioventricular izquierdo. Utilizamos 58 corazones de individuos chilenos, 28 fijados en formaldehído al 10 por ciento y 30 frescos de individuos brasileños, de edades comprendidas entre 18 y 84 años, de ambos sexos y sin aparente cirugía cardíaca. Disecamos la región de ambos surcos coronarios, para luego clasificar las piezas según el tipo de dominancia coronaria. Luego, los atrios fueron resecados dejando visibles los anillos atrioventriculares y su relación con las arterias coronarias. Se efectuaron mediciones de la distancia de las arterias coronarias y sus ramas en relación al anillo atrioventricular izquierdo. Se establecieron 5 puntos en la porción posterior del anillo, distribuidos en sentido antihorario. Los puntos 1 y 5 localizados a nivel de las comisuras anterior y posterior, respectivamente. La menor distancia entre las ramas de las arterias coronarias y el anillo atrioventricular izquierdo se presentó en corazones con dominancia coronaria izquierda, y fue de 3,8 mm (corazones fijados) y 3,0 mm (corazones frescos).El tercio proximal de la rama circunfleja, asociado a una mayor proximidad al anillo mitral, constituye el área de mayor predisposición a una lesión iatrogénica durante un reemplazo y/o plastía valvar.

The relationships between the coronary arteries and the atrioventricular rings are important in cases of substitution or plastic of the corresponding valve. The vicinity of the circumflex branch of the left coronary artery to the left atrioventricular ring, at level of the previous corner, it has brought surgical complications, in some cases with fatal results. Due to this, we consider necessary to study the relationships biometric between the coronary arteries and the left atrioventricular ring. We use 58 hearts, 28 fixed hearts of Chilean individuals and 30 fresh hearts of Brazilian individuals, of ages between 18 and 84 years, of both sexes and without apparent heart surgery. The region of both coronary sulcus was dissected and we classified the pieces according to the type of coronary dominance. Later on, the atrium were dried up leaving visible the atrioventricular rings and their relationship with the coronary arteries. Measurement of the distances were made (in mm) of the coronary arteries and their branches, in relation to the left atrioventricular ring. Five points settled down in the later portion of the ring, distributed in having felt anti-timetable. The points 1 and 5 located at level of the previous and later corners, respectively. The smallest distance between the branches of the coronary arteries and the left atrioventricular ring was presented in hearts with left coronary dominance, and it was of 3,8 mm (fixed hearts) and 3,0 mm (fresh hearts).

Origem das artérias dos nós sinoatrial e atrioventricular em população do sul da Índia: um estudo angiográfico / Origin of the sinoatrial and atrioventricular nodal arteries in South Indians: an angiographic study / Origen de las arterias de los nódulos sinusal y atrioventricular en población del Sur de la India: un estudio angiográfico

Fundamento: Estudar o suprimento arterial do sistema condutor e sua correlação com a dominância das artérias coronárias em população do sul da Índia. Objetivo: Determinar angiograficamente as origens da artéria do nó sinoatrial (AnSA) e artéria do nó atrioventricular (AnAV) em indianos.Métodos: O estudo incluiu 300 pacientes consecutivos (114 do sexo feminino e 186 do sexo masculino; idade média, 55 anos), habitantes da região costeira ao sul da Índia, submetidos a cineangiocoronariografia devido a sintomas como dor no peito, angina pectoris ou teste ergométrico positivo. As angiografias incluíram ambas as artérias coronárias (direita e esquerda) em posição oblíqua anterior direita e esquerda. A origem da AnSA e AnAV a partir das artérias coronárias foi observada e correlacionada à dominância arterial. Resultados: O nó SA (sinoatrial) recebeu suprimento pela artéria coronária direita (ACD) em 53% dos casos, pelo ramo circunflexo (Cx) da artéria coronária esquerda (ACE) em 42,66% dos casos, e em 4,33% dos casos esse nó foi irrigado por ambas as artérias coronárias. O nó AV (atrioventricular) também recebeu suprimento sanguíneo com mais frequência da ACD (72,33% dos casos) do que do ramo Cx da ACE (27,66%). Surpreendentemente, em nenhum caso este nó recebeu suprimento de ambas as artérias coronárias. Conclusão: Os resultados do presente estudo podem auxiliar os cirurgiões cardíacos, sobretudo em cirurgias relacionadas a valvopatias, devido à franca proximidade entre os ramos nodais e o complexo valvar.

Background: To study the arterial supply of the conducting system and its correlation with the dominance of the coronary arteries in the South Indian population. Objective: To determine angiographically the origins of the sinoatrial nodal artery (SAna) and atrioventricular nodal artery (AVna) in Indians. Methods: The study included 300 consecutive patients (114 females, 186 males; mean age, 55 years) living in the southern coastal region of India, who underwent coronary angiography either for the symptoms of chest pain, angina pectoris or positive Treadmill Test. The angiograms contained both coronary arteries (right and left) in the right and left anterior oblique position. The origin of SAna and AVna from the coronary arteries was observed and correlated with the arterial dominance.Results: The SA (sinoatrial) node was supplied by the right coronary artery (RCA) in 53% of the cases, by the circumflex (Cx) branch of left coronary artery (LCA) in 42.66%, and by both coronary arteries in 4.33% of cases. The AV (atrioventricular) node was also more often supplied by the RCA (72.33% of cases) than by the Cx branch of the LCA (27.66%), and surprisingly in none of the cases was this node supplied by both coronary arteries. Conclusion: The results of the present study may help cardiac surgeons, particularly in surgeries related to certain valvular disorders, due to the proximity of the nodal branches to the valve complex.

Fundamento: Estudiar el suministro arterial del sistema conductor y su correlación con la dominancia de las arterias coronarias en población del Sur de la India. Objetivo: Determinar angiográficamente los orígenes de la arteria del nódulo sinusal (AnSA) y la arteria del nódulo atrioventricular (AnAV) en indios. Métodos: El estudio incluyó 300 pacientes consecutivos (114 del sexo femenino y 186 del sexo masculino; edad promedio, 55 años), habitantes de la región costera al Sur de la India, sometidos a cineangiocoronariografía debido a síntomas como dolor en el pecho, angina pectoris o test ergométrico positivo. Las angiografías incluyeron ambas arterias coronarias (derecha e izquierda) en posición oblicua anterior derecha e izquierda. El origen de la AnSA y AnAV a partir de las arterias coronarias se observó y se correlacionó con la dominancia arterial. Resultados: El nódulo SA (sinusal) recibió suministro por la arteria coronaria derecha (ACD) en el 53% de los casos, por la rama circunfleja (Cx) de la arteria coronaria izquierda (ACI) en el 42,66% de los casos, y en el 4,33% de los casos este nódulo fue irrigado por ambas arterias coronarias. El nódulo AV (atrioventricular) también recibió suministro sanguíneo con más frecuencia de la ACD (72,33% de los casos) que la rama Cx de la ACI (27,66%). Sorprendentemente, en ningún caso este nódulo recibió suministro de ambas arterias coronarias.Conclusión: Los resultados del presente estudio pueden auxiliar a los cirujanos cardíacos, sobre todo en cirugías relacionadas a valvulopatías, debido a la franca proximidad entre las ramas nodales y el complejo valvular.

Modification of atrioventricular conduction in dogs by laser irradiation of Koch's triangle guided by balloon-tipped cardioscope.

PURPOSE: This study assessed the feasibility of modification of atrioventricular (AV) conduction under direct vision with a new ablation system using laser energy. METHODS AND RESULTS: In 23 anesthetized dogs, a combined laser and balloon-tipped endoscope was introduced into the right atrium after right thoracotomy. Koch's triangle was easily identified in all dogs endoscopically. Nd:YAG laser energy was delivered through an optical fiber positioned inside the saline-filled balloon to the middle portion of Koch's triangle in eight dogs (mid-Koch group) and to the posterior portion in 12 dogs (postero-Koch group). Complete AV block was achieved in five of eight dogs in the mid-Koch group. In the postero-Koch group, anterograde Wenckebach cycle length increased significantly from 178+/-23 ms to 202+/-37 ms (P = 0.008). CONCLUSION: Selective laser ablation of Koch's triangle is feasible with a combined laser and balloon-tipped endoscope.

Anatomic aspects of the atrioventricular junction influencing radiofrequency Cox maze IV procedures.

OBJECTIVE: This study analyzes the anatomic structure of the mitral and tricuspid annuli, their relationship with the coronary arteries and veins, and how this anatomic distribution may affect atrial ablation with bipolar radiofrequency clamps, the only technology that ensures transmurality. METHODS: Nine explanted fresh human hearts were studied, two of them with left coronary dominance. Two types of bipolar radiofrequency clamps were positioned to reach the mitral and tricuspid annuli, and relationships within the atrioventricular junction were analyzed, including coronary sinus and coronary arteries. RESULTS: In all hearts studied, the coronary arteries and veins within the adipose tissue of the right or left atrioventricular groove lay in the atrial side, 3 to 18 mm away from the mitral or tricuspid annuli. When the bipolar radiofrequency clamp was closed toward the mitral annulus, the coronary sinus was always included between the jaws, and in left coronary-dominant hearts, the circumflex artery was also included. Nevertheless, the clamp never reached the annulus owing to the increase in thickness of the adipose tissue around the groove and the ventricular mass, leaving 5 to 10 mm of atrial myocardium free from the radiofrequency electrodes. In the right atrium, clamp placement toward the tricuspid annulus excluding the right coronary left 8 to 18 mm of atrial muscle free from the bipolar electrodes. CONCLUSIONS: Bipolar radiofrequency clamps are not sufficient to complete a Cox maze IV procedure. Moreover, they may compromise coronary arteries in patients with left coronary dominance. Lines to the atrioventricular annuli need to be completed with the cut-and-sew technique or with alternative monopolar energy devices.

Anatomical aspects of the arterial blood supply to the sinoatrial and atrioventricular nodes of the human heart.

Classic anatomical dissection of 150 hearts from adults aged 18 - 80 years was performed. The sinoatrial (SA) node artery was most frequently a large atrial branch of the right coronary artery (63%), arising at a mean distance of 1.2 cm (range 0.2 - 2.2 cm) from its beginning, with a mean external diameter of 1.7 mm (range 1 - 3 mm). In 37% of cases the SA node artery was a branch of the left coronary artery or one of its branches, with an initial mean external diameter of 2.2 mm (range 2 - 3 mm). The origin of the SA node artery was not related to coronary arterial dominance. The atrioventricular (AV) node artery was the first and longest inferior septal perforating branch of the right (90%) or left (10%) coronary artery, arising from the U- or V-shaped segment of the corresponding artery at the level of the crux cordis. Mean external diameter was 2 mm (range 1 - 3.5 mm). The origin of the AV node artery was dependent on coronary arterial dominance. Identification of the anatomical variants of the arterial blood supply to the SA and AV nodes may help in overcoming potential difficulties in treating arrhythmias and in mitral valve surgery.

Incidence and pathophysiology of atrioventricular block following mitral valve replacement and ring annuloplasty.

BACKGROUND: In this retrospective study we evaluate the causative mechanisms underlying postoperative atrioventricular block (AVB) following mitral valve replacement and mitral valve annuloplasty. METHODS: Between January 1990 and December 2003, 391 patients underwent mitral valve replacement or ring annuloplasty and quadrangular resection. Exclusion criteria were preoperative AV block, two or three valvular procedures, reoperations and procedures combined with coronary artery bypass grafting. The presence of the postoperative AVB was compared with preoperative and intraoperative variables. On 55 post-mortem specimens the relationship between the AV node, AV node artery and mitral valve annulus was investigated. RESULTS: The mean age was 59+/-14 years and 44% of patients were female. Postoperatively AVB occurred in 92 (23.5%) patients. AVB III was found in 17 (4%) patents, in whom a pacemaker was implanted within median interval of 4 days. Second degree AVB occurred and first degree AVB in five (1.3%) and in 70 (18%) patients respectively. In dry dissected human hearts in 23% of investigated cases the AV node artery was discovered to run close to the annulus of the mitral valve. CONCLUSIONS: Data collected in this study showed that, sotalol and amiodarone as well as a prolonged cross-clamp time may slightly influence the 23% incidence of postoperative AVB. The morphological investigation showed that the AV node artery runs in close proximity to the annulus in 23% of cases. We speculate that damage of the AV node artery may play a role in development of AVB.

Morphology of the atrioventricular junction in 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.

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.

Anatomia do aparelho valvar atrioventricular direito em ovinos / Anatomical of the right atrioventricular valve apparatus in sheep

Objetivo: Este estudo teve por objetivo descrever a constituição do aparelho valvar atrioventricular direito em ovinos, bem como as principais estruturas anatômicas presentes na valva atrioventricular direita. Métodos: O material constou de 40 corações de ovinos adultos jovens, sendo 18 fêmeas e 22 machos. Os corações foram dissecados, deixando exposto a valva atrioventricular direita, preservando a integridade do aparelho valvar. Após realizar a dissecção, todas as peças foram conservados pela técnica de Giacomini. Analizou-se as seguintes estruturas: o perímetro do anel fibroso; número, localização e morfometria da largura e profundidade das cúspide habituais e supranumerárias; número e orientação das cordas tendíneas; freqüência e localização de cúspides comissurais; número e morfometria da largura e profundidade das cúspides habituais e supranumerárias; número e tipos de cordas tendíneas; freqüência e localização de cúspides comissurais; número e morfometria; altura e largura do ponto médio dos músculos papilares e a correlação entre dados obtidos. Resultado: A média do perímetro do anel fibroso nos machos foi de 79,128mm, já nas fêmeas foi de 78,463mm, portanto, o diâmetro do atrioventricular não esta condicionado ao sexo. Já o perímetro do anel fibroso variou, quando foi relacionado com o peso, o valor do coeficiente de determinação mostra que 59,7 por cento da variação do peso do coração é responsável pela variação do comprimento do anel fibroso. A valva atrioventricular direita em ovinos é constituída por três cúspides 45 por cento dos casos, quatro cúspide 35 por cento e com 5 cúspide de 20 por cento, sendo que as cúspides habituais (septal, parietal e angular), estiveram presente em todos os corações. A cúspide angular apresentou uma profundidade média de 14,45mm e uma largura média de 13,38mm. A profundidade média da cúspide parietal foi de 12,43mm e sua largura média foi de 1.3,13mm. A cúspide septal apresentou uma média de profundidade de 13,29 e de largura 15,64mm. Já para as cúspides supranumerária a média da profundidade foi de 7,16mm e a largura foi de 6,59mm, mostrando ser uma cúspide independente das habituais e também não pode ser classificada como comissurais, pois elas apresentam diferenças significativas entre elas...

Examination of the cardiac conduction system: forensic application in cases of sudden cardiac death.

Forensic pathologists may occasionally encounter cases of apparent sudden cardiac death without gross cardiac abnormality. In some of these cases, evaluation of the cardiac conduction system may reveal pathologic lesions which may act as the substrates for ventricular tachyarrhythmias and sudden death. Sample case studies are used to illustrate the suggested criteria and techniques for examination, and commonly-encountered pathologic lesions and normal variants are discussed.

The clinical anatomy of the sinus node artery.

BACKGROUND: Our basic aim was to describe the topographic relation between the sinus node artery and the superior posterior border of the interatrial septum with regard to the sinus node dysfunction that follows the superior transseptal approach to the mitral valve. METHODS: During our study 50 human hearts without previous pathologic alterations were analyzed. The position of the sinus node and the course of the sinus node artery were investigated. For identification of the origin of the artery, selective coronary angiograms were performed. The course of sinus node artery and its topographic relation to the interatrial septum was identified by the dry dissections of the hearts. Based on histologic and dry dissected specimens the exact position of the sinus node was determined. RESULTS: We found that the sinus node artery originates from the right coronary artery in 66% of examined cases and from the left coronary artery in 34% of cases. The sinus node artery crosses the superior posterior border of the interatrial septum in 54% of cases. CONCLUSIONS: Our results were compared with clinical studies focusing the incidence of the sinus rhythm disturbance after the superior transseptal approach. The incidence of rhythm disturbance varies from 52% to 60% of cases. Comparing our morphologic and clinical results we can state that the risk for intraoperative damage to the sinus node artery during the superior transseptal approach to the mitral valve is high.

New findings on the origin of the blood supply to the atrioventricular node. Clinical and surgical significance.

The anatomy of the heart's conduction system and of its blood supply have been research topics for many years. However, several proposals have never been demonstrated. In this paper, we describe 2 vascular conduits that have never before been objectively shown to supply the conduction system. Twenty human hearts from subjects aged between 15 and 65 years--with and without coronary disease--were dissected after anterograde and retrograde injection with latex butaclor E-650 by means of a technique developed by the authors. In 40% of these hearts, Kugel's artery was found to supply the atrioventricular node. The right descending superior artery supplied the atrioventricular node in 70% of the hearts dissected. These findings may be of major significance both in clinical cardiology and in cardiovascular surgery.

The artery of the atrioventricular node: an anatomic study based on 38 injection-dissections.

The origin and course of the artery of the atrioventricular node (AAVN) was studied in 45 anatomic specimens by the method of injection-dissection in 38 human hearts removed at medicolegal autopsies from black Senegalese subjects. Though sometimes double, the AAVN is classically solitary. Its coronary origin, which is always distal, occurred on the right side in the great majority of cases, at the level of the "U-turn of James", and on the left side at the level of the terminal portion of the circumflex a. At the level of Koch's triangle, its course is marked by a close relationship with the zone of attachment of the septal cusp of the right atrioventricular valve on the one hand, and with the orifice of the coronary sinus on the other. In cardiac surgery, respect for the area of Koch's triangle, the base of the interatrial septum and the region of the intersection of the cardiac sulci will reduce the risks of injury to the AAVN.

Surgical anatomy of accessory connections of atrioventricular conduction.

Forty-nine descriptions of accessory pathways of atrioventricular (AV) conduction have been analyzed in the search for reasons for an occasional failure of interruption by operation. The validity of the steps now used for open interruption of connections was confirmed. Several possible but highly speculative reasons were found for failure. A pathway might remain intact after operation because atrial muscle on the AV valve may act as a pathway route after an atriotomy made just above the annulus. In another situation, the AV valve myocardium might be continuous with a papillary muscle directly attached to the valve. The small, middle, and great coronary veins, when budding from the coronary sinus, might carry with them an AV connection that escaped the invasion of the primitive AV junction by sulcus tissue. Final proof of these conjectures awaits more studies of hearts with accessory pathways of AV conduction.