Anatomical Study of the Cardiac Veins and their Tributaries in Bovines (Bos indicus) in Comparison with Humans and Other Animal Species / Estudio Anatómico de las Venas Cardiacas y sus Tributarias en Bovinos (Bos indicus) en Comparación con Humanos y Otras Especies Animales

SUMMARY: In bovines, anatomical observations of the coronary vascular tree describe qualitative characteristics. The objective of this study was to morphometrically characterize the coronary veins and their tributaries in cattle. An arcuate application with 2.0 silk was performed around the ostium of the coronary sinus of 28 bovine hearts and a number 14 catheter was placed, through which semi- synthetic polyester resin and mineral blue color was perfused. In 22 hearts (78.6 %) the great cardiac vein was originated at the cardiac apex. The configuration of the arteriovenous trigone was mainly closed inferior and superior types (50 %). The caliber of the great cardiac vein at the level of the atrioventricular sulcus was 6.7 +/- 1.2 mm. The origin of the left marginal vein was observed in the lower third of the left cardiac margin (53.6 %), its distal caliber was 4.1 +/- 0.8 mm and its drainage was at the level of the great cardiac vein. The middle cardiac vein originated from the cardiac apex in 78.6 % of the samples, emptied mainly into the coronary sinus (82.1 %) and its distal caliber was 4.7 +/- 0.9 mm. Anastomoses occurred in 28.6 % of the hearts, being found in most cases between the middle cardiac vein and the great cardiac vein (50 %), which was significant compared to other anastomoses (p<0.001). The length of the coronary sinus was 42.2 +/- 5.1 mm, its distal caliber was 13.8 +/- 2 mm, and its shape was cylindrical. Myocardial bridges were found in 3 hearts (10.7 %) mainly in the lower third of the middle cardiac vein (66.6 %). Most of the main coronary veins drained into the coronary sinus, with some cases with atypical outlets and the presence of a high percentage of anastomosis that serves to improve cardiac venous drainage in case of venous compression or obstruction.

En bovinos, las observaciones anatómicas de árbol vascular coronario describen características cualitativas. El objetivo de este estudio fue caracterizar morfométricamente las venas coronarias y sus tributarias en bovinos. Se realizó una aplicatura arciforme con seda 2.0 alrededor del ostium del seno coronario de 28 corazones de bovino y se colocó un catéter número 14, a través del cual se perfundió resina de poliéster semisintética y color azul mineral. La vena cardiaca magna se originó en 22 corazones (78,6 %) en el ápex cardiaco. La configuración del trígono arteriovenoso fue principalmente cerrado inferior y superior (50 %). El calibre de la vena cardiaca magna a nivel del surco atrioventricular fue 6,7 +/- 1,2 mm. El origen de la vena marginal izquierda se observó en el tercio inferior del margen izquierdo cardiaco (53,6 %), su calibre distal fue 4,1 +/- 0,8 mm y su desembocadura fue a nivel de la vena cardiaca magna. La vena cardiaca media se originó en el ápex cardiaco en el 78,6 % de las muestras, desembocó principalmente en el seno coronario (82.1 %) y su calibre distal fue 4,7 +/- 0,9 mm. Se presentó anastomosis en el 28,6 % de los corazones, encontrándose en la mayoría de los casos entre la vena cardiaca media y la vena cardiaca magna (50 %), lo cual fue significativo en comparación con otras anastomosis (p<0,001). La longitud del seno coronario fue 42,2 +/- 5,1 mm, su calibre distal fue 13,8 +/- 2 mm y su forma fue cilíndrica. Se encontró puentes miocárdicos en 3 corazones (10,7 %) y en el tercio inferior de la vena cardiaca media (66,6 %). La mayoría de las venas coronarias principales desembocan en el seno coronario, con algunos casos con desembocaduras atípicas y la presencia de un alto porcentaje de anastomosis que sirve para mejorar el drenaje venoso cardiaco en caso de compresión u obstrucción venosa.

Morphological Assessment and Possible Clinical Implications of the Left Ventricle Papillary Muscles. Study in a Colombian Population Sample

SUMMARY: Papillary muscles in the left ventricle present multiple anatomic expressions that are relevant for medical fields focusing on the understanding of clinical events involving these structures. Here, the aim was to perform a morphological characterization of the left ventricle papillary muscles in a sample of Colombian population. In the study were included eighty-two hearts from male individuals who underwent autopsy at the Institute of Legal Medicine and Forensic Sciences in Bucaramanga, Colombia. In each heart was carefully performed a longitudinal incision on the obtuse margin to visualize the papillary muscles. Data set was registered, and analysis of the continuous and categorical variables was carried out. Single anterior papillary muscle was observed in 74 samples (90.2 %) whereas this represented only 48 specimens (58.5 %) for the posterior papillary muscle (p = 0.3). Mean length and breadth of the anterior muscle were 29.9 ± 4.94 and 11.74 ± 2.75 mm, and those for the posterior muscle were 27.42 ± 7.08 and 10.83 ± 4.08 mm. Truncated apical shape was the most frequent type observed on the papillary muscles, anterior 41 (50 %) and posterior 37 (45.1 %), followed by flat-topped in the anterior 25 (30.5 %) and bifurcated in posterior muscle 14 (17.1 %). A mean of 9.04 ± 2.75 chordae raised from the anterior and 7.50 ± 3.3 from posterior papillary muscle. In our study we observed a higher incidence of single papillary muscles and slightly larger dimensions than information reported in the literature. The anatomic diversity of the papillary muscles should be considered for the correct image interpretation, valve implantation and performance evaluation on myocardial ischemic events.

Los músculos papilares del ventrículo izquierdo presentan múltiples expresiones anatómicas que son relevantes para las áreas médicas que se centran en la comprensión de los eventos clínicos que involucran estas estructuras. El objetivo fue realizar una caracterización morfológica de los músculos papilares del ventrículo izquierdo en una muestra de población colombiana. En el estudio se incluyeron ochenta y dos corazones de individuos masculinos a los que se les realizó autopsia en el Instituto de Medicina Legal y Ciencias Forenses de Bucaramanga, Colombia. En cada corazón se realizó cuidadosamente una incisión longitudinal en el margen obtuso para visualizar los músculos papilares. Se registró el conjunto de datos y se realizó el análisis de las variables continuas y categóricas. Se observó un solo músculo papilar anterior en 74 muestras (90,2 %), mientras que este rasgo se presentó en 48 muestras (58,5 %) para el músculo papilar posterior (p = 0,3). La longitud y anchura media del músculo anterior fueron 29,9 ± 4,94 y 11,74 ± 2,75 mm, y las del músculo posterior fueron 27,42 ± 7,08 y 10,83 ± 4,08 mm. La forma apical truncada fue el tipo más frecuente observado en los músculos papilares, anterior 41 (50 %) y posterior 37 (45,1 %), seguido de la forma plana en los 25 anteriores (30,5 %) y bifurcada en el músculo posterior 14 (17,1 %). Una media de 9,04 ± 2,75 cuerdas elevadas desde el músculo papilar anterior y 7,50 ± 3,3 desde posterior. En nuestro estudio observamos una mayor incidencia de músculos papilares únicos y dimensiones ligeramente mayores que la información reportada en la literatura. La diversidad anatómica de los músculos papilares debe ser considerada para la correcta interpretación de imágenes, implantación valvular y evaluación del desempeño en eventos isquémicos miocárdicos.

Histopathological changes in the electrical conduction of cardiac nodes after acute myocardial infarction in dogs and horses, compared with findings in humans: A histological, morphometrical, and immunohistochemical study.

Background and Aim: The heart conduction system is responsible for the occurrence of various types of cardiac arrhythmia. This study aimed to histologically and morphometrically describe damaged cardiac nodes during acute myocardial infarction and to compare them with normal tissues in dogs and horses. Materials and Methods: This study describes the morphometry of cardiac nodes in five dogs and five elderly horses that succumbed to sudden cardiac death (SCD). A computerized morphometric study was conducted to determine the number of cells composing the nodes, different shape and size parameters of nodes, and their relationship with degenerative changes due to cardiac conditions. Results: In both species, the sinoatrial node (SAN) was ovoid in shape whereas the atrioventricular node (AVN) was pyramidal in shape. The percentage of collagen fibers inside the SAN of dogs (47%) and horses (50%) was found to be higher than that of cells. In contrast, the percentage of cells in the AVN of dogs (24%) and horses (16%) was higher than that of connective tissues. In the SAN, the area (p = 0.09), maximum diameter (<0.001), and mean diameter (0.003) of P cells were larger in dogs than in horses. Conclusion: Overall, the SAN cells and surrounding cardiomyocytes in dogs and horses as well as the AVN cells in dogs that succumbed to SCD decreased in size compared with those in normal hearts.

Comparison of coronary arteries morphometry and distribution in bovines with humans and other animal species.

Background: The left coronary artery (LCA) in the bovines is more developed than the right. Aim: The objective of the study is to describe the bovine coronary system from a morphological point of view, including the morphometry and its distribution. Methods: Arciform suture with 2.0 silk was applied around the sinus orifice and coronary ostium and a number 14 catheter was installed, to perfuse semi-synthetic polyester resin, consisting of a mixture of 85% GP40L palatal with 15% styrene with red color mineral. Results: The average weight of 28 bovine hearts used in our study was 1.534.1 kg. The right coronary artery had a proximal caliber of 5 +/- 0.9 mm. The LCA caliber and length were 9.4 +/- 1.2 and 18.3 +/- 4.8 mm, respectively. This artery was divided into two branches in 85.7% of the cases and trifurcated in 14.3%. The paraconal interventricular branch (PIB) ended more frequently in the apex (46.4%), and its proximal caliber was 6.4 +/- 1.4 mm. The left circumflex branch ended in 82.1% in the subsinusal interventricular sulcus, and its proximal caliber was 5.9 +/- 1.2 mm. The proximal calibers of the PIB and the left circumflex branch did not present statistically significant differences (p = 0.137). The sinoatrial branch presented a dual origin (right and LCA) in 46.4% of the cases and a single origin from the LCA in 53.6% of the samples. In the evaluated hearts, left coronary dominance was observed in most cases (96.4%). Their presence of anastomosis between the branches of the coronary arteries was observed in 57.1% of cases. Conclusion: The presence of a myocardial bridge was found in six hearts (21.4%). In bovines, a high percentage of anastomosis was found, a protective factor in obstruction of the coronary arterial branches.

Fourier analysis of collagen bundle orientation in myocardial infarction scars.

Collagen bundle orientation (CBO) in myocardial infarct scars plays a major role in scar mechanics and complications after infarction. We aim to compare four histopathological methods for CBO measurement in myocardial scarring. Myocardial infarction was induced in 21 pigs by balloon coronary occlusion. Scar samples were obtained at 4 weeks, stained with Masson's trichrome, Picrosirius red, and Hematoxylin-Eosin (H&E), and photographed using light, polarized light microscopy, and confocal microscopy, respectively. Masson's trichrome images were also optimized to remove non-collagenous structures. Two observers measured CBO by means of a semi-automated, Fourier analysis protocol. Interrater reliability and comparability between techniques were studied by the intraclass correlation coefficient (ICC) and Bland-Altman (B&A) plots and limits of agreement. Fourier analysis showed an almost perfect interrater reliability for each technique (ICC ≥ 0.95, p < 0.001 in all cases). CBO showed more randomly oriented values in Masson's trichrome and worse comparability with other techniques (ICC vs. Picrosirius red: 0.79 [0.47-0.91], p = 0.001; vs. H&E-confocal: 0.70 [0.26-0.88], p = 0.005). However, optimized Masson's trichrome showed almost perfect agreement with Picrosirius red (ICC 0.84 [0.6-0.94], p < 0.001) and H&E-confocal (ICC 0.81 [0.54-0.92], p < 0.001), as well as these latter techniques between each other (ICC 0.84 [0.60-0.93], p < 0.001). In summary, a semi-automated, Fourier-based method can provide highly reproducible CBO measurements in four different histopathological techniques. Masson's trichrome tends to provide more randomly oriented CBO index values, probably due to non-specific visualization of non-collagenous structures. However, optimization of Masson's trichrome microphotographs to remove non-collagenous components provides an almost perfect comparability between this technique, Picrosirius red and H&E-confocal.

Morphometric analysis of the His bundle (atrioventricular fascicle) in humans and other animal species. Histological and immunohistochemical study.

The His bundle is a part of the specialized electrical conduction system that provides a connection between the atrial and ventricular myocardial compartments in both normal and abnormal hearts. The aim of this study was to perform a morphometric analysis of His bundle characteristics of in humans, dogs, horses and pigs and compare them in these studied species. Histological sections of 5 µm thickness were obtained and stained with hematoxylin-eosin and Masson's trichrome; the desmin and periodic acid-Schiff methods were also used for precise identification of cells. The His bundle was found to be longer in horses (2.85 ± 1.02 mm) and pigs (1.77 ± 0.9 mm) than in dogs (1.53 ± 0.8 mm) or humans, in which it was shortest (1.06 ± 0.6 mm). The area and diameters in His bundle cells, were significantly larger in pigs and horses than in humans (p < 0.001) or dogs (p < 0.001). We found two organizational patterns of His bundle components: group I, with large cells and a high amount of collagen fibers in ungulates (pigs and horses); and group II, with smaller cells and lower abundance of collagen fibers in humans and dogs. Documenting cell size variations in the His bundle allows us not only to identify this bundle by histological or anatomical location but also to differentiate these cells from others such as nodal or Purkinje cells. Our analysis revealed that His bundle cells have discrete identities based on their morphometric and histological characteristics.

Identification to cardiac conduction cells in humans and pigs according to their zonal distribution, using histological, immunohistochemical and morphometric study.

Histologically, the cardiac conduction network is formed of electrically isolated subendocardial fibers that comprise specialized cells with fewer myofibrils and mitochondria than cardiomyocytes. Our aim is to uncover regional variations of cardiac conduction fibers through histological and morphometric study in a porcine and human model. We analyzed five male adult human hearts and five male pig hearts. The left ventricles were dissected and sectioned in the axial plane into three parts: basal, middle third and apex regions. Cardiac conduction fibers study was carried out using hematoxylin-eosin and Masson's trichrome staining, and cardiac conduction cells and their junctions were identified using desmin, and a PAS method. Cardiac conduction fibers were difficult to pinpoint in humans, mostly showing a darker color or equal to cardiomyocytes. Cardiac conduction fibers in humans were in the subendocardium and in pigs in the myocardium and subendocardium. Cardiac conduction fibers were located mainly in the septal region in both humans and pigs. In our morphometric analysis, we were able to determine that cardiac conduction cells in humans (18.52 +/- 5.41 µm) and pigs (21.32 +/- 6.45 µm) were large, compared to cardiomyocytes. Conduction fiber-myocardial junctions were present in 10% in humans and 24.2% in pigs. The performance of immunohistochemical methods made it possible to improve the identification of cardiac conduction cells in the species studied. Study of cardiac conduction fibers and cells and their myocardial junctions is vital to gain insight into their normal distribution in the species analyzed, and thus advance the use of pigs in experimental models of the cardiac conduction system in humans.

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.