The structure of the vascular system of the septomarginal trabecula in the heart of an adult.

BACKGROUND: In cardiology, the paths of the arteries penetrating the septomarginal trabecula (SMT) are especially important. They provide blood supply to the apparatus of the right atrioventricular orifice and often form anastomoses with the system of the right coronary artery. Despite this, only a few publications discuss the morphological aspect of the septomarginal trabecula, and available histological analyses seldom deal with its blood supply. OBJECTIVES: The aim of this study was to analyze the vessel structure of the septomarginal trabecula in terms of the variability of the area of the cross-section of the lumen and the muscular layer of the artery. MATERIAL AND METHODS: The study was carried out on the material of 50 human hearts from adults of both sexes. The material was divided into 4 morphological types. Histological examinations were conducted by means of classic staining methods. RESULTS: At the initial cross-section of the septomarginal trabecula, the area of the cross-section increased to half of the length of the trabecula, and then it started to decrease. This is connected with the thickening of the inner muscular layer of the artery, which proportionally takes up more area of the cross-section of the whole artery of the SMT. The total area of the cross-section of all vessels in both types examined was also the largest in the middle part of the SMT. Furthermore, the results of this study confirm the presence of a connection between both systems of coronary arteries. CONCLUSIONS: As the septomarginal trabecula passes through the lumen of the right ventricle, its arteries become exposed to the influence of the factors which may evoke a biological response from the walls of this vessel, causing the thickening of the muscular layer and, as a result, of the section of the whole artery, in particular its middle part.

Cardiac tumors in children: A 20-year review of clinical presentation, diagnostics and treatment.

BACKGROUND: The use of new imaging techniques has contributed significantly to earlier diagnosis and treatment of cardiac tumors. OBJECTIVES: The aim of the study was to analyze data from children with cardiac tumors in terms of clinical presentation, the role of noninvasive diagnostic procedures and the long-term outcome. MATERIAL AND METHODS: The data analyzed retrospectively concerned 30 children in whom cardiac tumors were diagnosed from January 1995 to July 2015. The cardiac evaluation included a review of the subjects' medical records and medical history, a physical examination, standard 12-lead electrocardiography, echocardiography and 24-h Holter ECG monitoring at the time of diagnosis and at 6-12 month intervals during the follow-up at the authors' outpatient clinic. RESULTS: Most of the children did not need cardiac surgery; surgical tumor excision was necessary in 3 cases only. There was 1 death in the follow-up period. Rhabdomyoma was diagnosed in 22 cases, and in 16 of them tuberous sclerosis was confirmed during the follow-up period. In the remaining 8 cases, fibroma was the most likely diagnosis. CONCLUSIONS: The symptomatology of cardiac tumors in children can vary greatly, from the absence of any symptoms up to heart failure and respiratory distress indicating the need for surgical intervention. The diagnosis of cardiac tumors relies almost exclusively on noninvasive imaging techniques. The observations in this study confirm the fact that the most common cardiac tumor in children is rhabdomyoma, which may disappear spontaneously. Most patients with cardiac tumors do not require treatment.

Variability of the Left Atrial Appendage in Human Hearts.

Atrial fibrillation increases the risk of thrombus formation. It is commonly responsible for cerebral stroke whereas less frequently for pulmonary embolism. The aim of the study was to describe the morphology of the left atrial appendage in the human heart with respect to sex, age and weight. Macroscopic examination was carried out on 100 left appendages taken from the hearts of the patients aged 18-77, both sexes. All hearts preserved in 4% water solution of formaldehyde carried neither marks of coronary artery disease nor congenital abnormalities. Three axes of appendage orientation were performed. After the appendage had been cut off, morphological examination was performed in long and perpendicular axes. Measurements of the appendages were taken from anatomical specimens and their silicone casts. We classified the left atrial appendage into 4 morphological groups according to the number of lobes. Most left atrial appendages in female population were composed of 2 lobes. In the male group typically 2 or 3-lobed appendages were observed. The mean left atrial appendage orifice ranged from 12.0 to 16.0 mm and the most significant difference in the orifices between males and females was observed in LAA type 2 (about 3.3 mm). A smaller orifice and narrower, tubular shape of the LAA lobes could explain a higher risk of thrombus formation during nonvalvular atrial fibrillation in women. Knowledge of anatomical variability of the LAA helps diagnose some undefined echoes in the appendage during transesophageal echocardiographic examination.

Macroscopic morphology of right atrial appendage in humans.

BACKGROUND AND AIM: Atrial fibrillation (AF) is a common arrhythmia in elderly people, and in many cases it is responsible for stroke or pulmonary embolism. One of the factors facilitating atrial thrombus formation is anatomical morphology of the atria, and especially the appendages. The pharmacological treatment of arrhythmia is generally focused on ventricular rate control. Electrical cardioversion is the preferred treatment method in the majority of clinics but it can occasionally produce the potentially dangerous complication of AF. METHODS: A macroscopic study was carried out on 40 (25 male [M], 15 female [F]) human hearts, 18-72 years of age, and a microscopic study in a group of 20 human right atrial appendages (RAA) (M 10, F 10), 18-72 years of age. Only hearts without anomalies were included in the study. Classical anatomical studies and statistic analyses were applied. RESULTS AND CONCLUSIONS: RAA is triangle shaped with a mean area of 2.73 cm2. Muscle fascicules build the wall of RAA and compose a dense net inside a chamber. Sagittal bundle connecting terminal crest with an apex of RAA was observed in all examined hearts. In microscopic specimens longitudinal and perpendicular fascicles were described.

Effects of physical activity during pregnancy and gestational weight gain on newborn weight and length at birth in Warminsko-Mazurskie province.

BACKGROUND: Epidemiological research has identified a relationship between maternal physical activity, early nutrition and infant birth weight with likelihood of developing future diseases. The aim of the study was to determine a relationship between gestational weight gain and physical activity during pregnancy to the nutritional status of newborns. MATERIAL AND METHODS: The presented study was conducted in the period from February 2010 until November 2012 in the gynecological and obstetric clinics in Warminsko-Mazurskie voivodeship with various levels of reference. The research subjects included 510 women in the puerperal period aged 18-36. The scope of the research included an assessment of the selected anthropometric parameters of both pregnant women (body mass, height, BMI, gestational weight gain) and newborns (infant birth weight, infant length, Ponderal Index), as well as an analysis of the connections between the gestational weight gain, physical activity during pregnancy and anthropometric parameters of newborns. RESULTS AND CONCLUSIONS: In the study group there was a significant percentage of women characterised by an inactive lifestyle and excessive gestational weight gain. There were significantly higher neonatal birth anthropometric parameters in women with abnormal excessive gestational weight gain than in women with normal and inappropriate - low gestational weight gain. The highest percentage of women with appropriate weight gain was observed in the group of women who are physically active, although this requires confirmation in larger population. Our studies have not shown statistically significant differences between the gestational weight gain and nutritional status of newborns in relation to the level of physical activity of pregnant women.

Tracheo-bronchial angles in the human fetus -- an anatomical, digital, and statistical study.

BACKGROUND: Both the advancement of visual techniques and intensive progress in perinatal medicine result in performing airway management in the fetus and neonate affected by life-threatening malformations. This study aimed to examine the 3 tracheo-bronchial angles, including the right and left bronchial angles, and the interbronchial angle, in the fetus at various gestational ages. MATERIAL AND METHODS: Using methods of anatomical dissection, digital image analysis with an adequate program (NIS-Elements BR 3.0, Nikon), and statistics, values of the two bronchial angles and their sum as the interbronchial angle were semi-automatically measured in 73 human fetuses at the age of 14-25 weeks, derived from spontaneous abortions and stillbirths. RESULTS: No male-female differences between the parameters studied were found. The 3 fetal tracheo-bronchial angles were found to be independent of age. The right bronchial angle ranged from 11.4° to 41.8°, and averaged 26.9±7.0° for the whole analyzed sample. The values of left bronchial angle varied from 24.8° to 64.8°, with the overall mean of 46.2±8.0°. As a consequence, the interbronchial angle totalled 36.2-96.6°, and averaged 73.1±12.7°. CONCLUSIONS: The tracheo-bronchial angles change independently of sex and fetal age. The left bronchial angle is wider than the right one. Values of the 3 tracheo-bronchial angles are unpredictable since their regression curves of best fit with relation to fetal age cannot be modelled. Both of the 2 bronchial angles and the interbronchial angle are of great relevance in the location of inhaled foreign bodies, and in the diagnosis cardiac diseases and mediastinal abnormalities.

Morphometric study of the T6 vertebra and its three ossification centers in the human fetus.

PURPOSE: Knowledge on the normative growth of the spine is critical in the prenatal detection of its abnormalities. We aimed to study the size of T6 vertebra in human fetuses with the crown-rump length of 115-265 mm. MATERIALS AND METHODS: Using the methods of computed tomography (Biograph mCT), digital image analysis (Osirix 3.9) and statistics, the normative growth of the T6 vertebral body and the three ossification centers of T6 vertebra in 55 spontaneously aborted human fetuses (27 males, 28 females) aged 17-30 weeks were studied. RESULTS: Neither male-female nor right-left significant differences were found. The height, transverse, and sagittal diameters of the T6 vertebral body followed natural logarithmic functions as y = -4.972 + 2.732 × ln(age) ± 0.253 (R (2) = 0.72), y = -14.862 + 6.426 × ln(age) ± 0.456 (R (2) = 0.82), and y = -10.990 + 4.982 × ln(age) ± 0.278 (R (2) = 0.89), respectively. Its cross-sectional area (CSA) rose proportionately as y = -19.909 + 1.664 × age ± 2.033 (R (2) = 0.89), whereas its volumetric growth followed the four-degree polynomial function y = 19.158 + 0.0002 × age(4) ± 7.942 (R (2) = 0.93). The T6 body ossification center grew logarithmically in both transverse and sagittal diameters as y = -14.784 + 6.115 × ln(age) ± 0.458 (R (2) = 0.81) and y = -12.065 + 5.019 × ln(age) ± 0.315 (R (2) = 0.87), and proportionately in both CSA and volume like y = -15.591 + 1.200 × age ± 1.470 (R (2) = 0.90) and y = -22.120 + 1.663 × age ± 1.869 (R (2) = 0.91), respectively. The ossification center-to-vertebral body volume ratio was gradually decreasing with age. On the right and left, the neural ossification centers revealed the following models: y = -15.188 + 6.332 × ln(age) ± 0.629 (R (2) = 0.72) and y = -15.991 + 6.600 × ln(age) ± 0.629 (R (2) = 0.74) for length, y = -6.716 + 2.814 × ln(age) ± 0.362 (R (2) = 0.61) and y = -7.058 + 2.976 × ln(age) ± 0.323 (R (2) = 0.67) for width, y = -5.665 + 0.591 × age ± 1.251 (R (2) = 0.86) and y = -11.281 + 0.853 × age ± 1.653 (R (2) = 0.78) for CSA, and y = -9.279 + 0.849 × age ± 2.302 (R (2) = 0.65) and y = -16.117 + 1.155 × age ± 1.832 (R (2) = 0.84) for volume, respectively. CONCLUSIONS: Neither sex nor laterality differences are found in the morphometric parameters of evolving T6 vertebra and its three ossification centers. The growth dynamics of the T6 vertebral body follow logarithmically for its height, and both sagittal and transverse diameters, linearly for its CSA, and four-degree polynomially for its volume. The three ossification centers of T6 vertebra increase logarithmically in both transverse and sagittal diameters, and linearly in both CSA and volume. The age-specific reference intervals for evolving T6 vertebra present the normative values of potential relevance in the diagnosis of congenital spinal defects.

False chordae tendineae in right ventricle of adult human hearts - morphological aspects.

INTRODUCTION: False chordae tendineae are fibrous-muscular bundles which do not interconnect with right atrioventricular valves. The structures have occasionally been described in the right ventricle. There are reports suggesting their influence on electromechanical processes taking place in the heart, in thromboembolic events as well as in the course of cardiac invasive procedures. The objective of the study was to perform a macroscopic evaluation of false chordae tendineae in the right ventricle. MATERIAL AND METHODS: The research specimens consisted of 100 hearts of adult humans, aged from 18 to 59 years, fixed in a solution of 10% formaldehyde and 98% ethanol. The ratio of false chordae tendineae to individual elements of the right ventricle, such as its walls, papillary muscles, septomarginal trabecula and the apex of the ventricle, was examined. RESULTS: During examination, six types of chordae tendineae were described based on the criterion of the type of structures they connected. The most common were false chordae connecting ventricle walls within its apex, while the least common were individual segments of papillary muscles. The research proved that the examined structures are morphologically extremely diverse. Substantial clinical implications of their presence seem very probable. CONCLUSIONS: The present work is the first of a scheduled series devoted to the problem of false chordae tendineae. Further analyses will cover the subject of morphological aspects in a microscopic perspective.

Quantitative anatomy of the growing abdominal aorta in human fetuses: an anatomical, digital and statistical study.

BACKGROUND: Advances in perinatal medicine have required an extensive knowledge of fetal aorto-iliac measurements. The present study was performed to compile reference data for dimensions of the abdominal aorta at varying gestational ages. MATERIAL/METHODS: Using the methods of anatomical dissection, digital-image analysis (Leica QWin Pro 16 system), and statistical analysis (Student's t-test, one-way ANOVA, post-hoc RIR Tukey test, regression analysis, and Wilcoxon signed-rank test), the growth of length (mm), proximal and distal external diameters (mm), and volume (mm3) of the abdominal aorta in 124 (60 male, 64 female) spontaneously aborted human fetuses aged 15-34 weeks was examined. RESULTS: No significant male-female differences were found. The length ranged from 9.35±1.24 to 36.29±4.98 mm, according to the linear function y=-14.596+1.519 × Age ±2.639 (R2=0.92; p<0.0001). The proximal external diameter varied from 1.18±0.25 to 5.19±0.49 mm, according to the linear pattern y=-2.065+0.212 × Age ±0.348 (R2=0.92; p<0.0001). The distal external diameter increased from 1.03±0.23 to 4.92±0.46 mm, in accordance with the linear model y=-2.097+0.203 × Age ±0.351 (R2=0.92; p<0.0001). Both length and proximal external diameter of the abdominal aorta indicated a proportionate evolution, because the length-to-proximal external diameter ratio was stable, following the linear function y=7.724-0.017 × Age ±0.925. The abdominal aorta volume ranged from 9.6±4.5 to 740.5±201.8 mm3, given by the quadratic function y=911-101 × Age +2.838 × Age2 ±78 (R2=0.89; p<0.0001). CONCLUSIONS: There are no significant differences between males and females for morphometric parameters of the abdominal aorta. The abdominal aorta grows linearly in both length and diameters, and parabolically in volume. These detailed morphometric data of the abdominal aorta provide a database for intra-uterine echographic examinations in the early diagnosis, monitoring and management of aorto-iliac malformations.

Morphological remarks regarding the structure of conduction system in the right ventricle.

BACKGROUND: The knowledge of conduction system morphology has a vital significance in cardiology and cardiac surgery - it enables to interpret pathologies and choose treatment. This has been confirmed by numerous accounts, both in the context of e.g. atrial fibrillation ablations as well as treating septum defects. Due to diversity and changeability of conduction system structure and their clinical implications, its thorough analyses seem to bear special importance. AIM: To examine the structure of selected elements of conduction system present in the right ventricle (RV). METHODS: Elements of conduction system present in RV of 6 foetuses (from 12 to 32 weeks of foetus age), 6 children (from 1 day to 7-year-old) and 10 adults (from 37 to 79-year-old) were histologically examined. Cross sections of 10 moderator bands and 10 anterior papillary muscles of adult human hearts were made. Specimens including membranous and muscular parts of the septum along with diverging moderator band were taken from a group of foetus, child and adult hearts. Cuttings of 10 micron width were stained with Masson's method in Goldner's modification. On the basis of the sections of membranous and muscular parts of the septum, the continuities of the elements of the conduction system were analysed. RESULTS: It was observed that in most cases the right branch of His' bundle locates itself deep in the muscular tissue of the septum irrespective of age; it is clearly separate along its whole run and gradually penetrates the muscular tissue with its fibers. Hardly ever does the right branch of His' bundle locate itself on the surface, subendocardially, with a minimum penetration into the muscular tissue. Moreover, in most cases, elements of conduction system are present in moderator band. The main tissue constituting its stroma is above all muscular tissue and to a lesser extent, connective tissue. In addition to this, fat tissue in variable proportion was also observed. In cross sections of the moderator band a distinctively circumscribed stripe of fibers of the conduction system was found. However, one could also observe samples in which its identification was not possible. CONCLUSIONS: The right branch of His bundle within the muscular part of the septum in most cases is located intramuscularly irrespective of age. The results of analyses prove a relatively constant character of the presence of the conduction system within the moderator band.

Short history of the autopsy: part II. From the second half of the 16th century to contemporary times.

We present the second part of our review concerning the history of autopsy. During the development of medicine the role of autopsy was obviously changing. Concurrently with the progress in the anatomical knowledge, the anatomists observed and noted both single anomalies and repetitive changes which correlated with symptoms in living patients. This is how anatomopathology came into being. We present the most famous people engaged in autopsy comprehension. We discuss main trends and ideas influencing the phenomenon of autopsy in the analyzed period: from sporadic public dissections, through theatra anatomica, introduction of autopsy to the hospital medicine and separation of anatomopathology as a medical speciality. The golden age of autopsy was the 19th century and the first half of the 20th century, with a consecutive decline in frequency. Nevertheless, despite the progress in diagnostics in vivo, it seems that autopsy will keep its important place in medicine according to the old motto "Mortui vivos docent" (the dead teach the living).

Assessment of a single monomorphic ventricular ectopy from the right ventricular outflow tract in standard and high resolution electrocardiogram.

INTRODUCTION: High-resolution electrocardiography (ECG-CREM) is a method based on digital electrocardiography. In order to facilitate the interpretation of the Crem records the technique of vectorcardiography was used. In comparison the origin of the ventricular premature complexes (VPCs) could be estimated based on a standard 12-lead electrocardiogram. The aim of the study was to assess the point of origin of the VPCs in ECG-CREM and correlate it with standard electrocardiography (ECG-Stand). MATERIAL AND METHODS: Our study included 26 patients (16 females, 10 males), aged 51-83 years (avg. 58.1 ±12.3), who presented with recurrent, during at least 6 months' observation, VPCs. The point of origin of VPCs was compared in both methods. RESULTS: The performed analysis of collected ECG-Stand records revealed the presence of arrhythmogenic focal points in six different locations (1, 3, 5, 7, 8, 9). However, we did not affirm their presence in points 2,4,6. They were most commonly located in RVOT zones 8 (30.7%), 9 (23.0%), 5 (23.0%), and most seldom in zones 1, 3, 7 (7.6% each). In the simultaneous record of ECG-CREM with a single VPC it was confirmed that the FPb zone was activated the most frequently (40.0%); the next in relation to frequency were SD and ST (20.0%). Less frequent VPCs have their origin in Crem zones SP, FPa and SB (6.6%). CONCLUSIONS: Electrocardiogram of high signal resolution (ECG-CREM) might be useful in recognition of the origin of ventricular premature complexes from RVOT.

Morphogenetic aspects of the septomarginal trabecula in the human heart.

INTRODUCTION: The septomarginal trabecula is a constant element of the anatomy of the human heart, which connects the interventricular septum and the anterior wall of the right ventricle. Considering the diversity of opinions about the structure and numerous studies suggesting its important role in haemodynamics and conduction of electrical impulses in the heart, we decided to study this element in detail. MATERIAL AND METHODS: The research was conducted on 220 human hearts. Attention was mainly paid to the structure and topography of the trabecula. Its relation to the anterior papillary muscle was also a part of the study. RESULTS: The presence of this morphologically diverse element was confirmed in each of the studied hearts. In most cases the trabecula originated from the upper part of the interventricular septum, separating at an angle increasing proportionally to the number of branches of the crista supraventricularis as well as the number of secondary trabeculae. The criteria established for the study, which included the course of the trabecula in the lumen of the right ventricle and its relation to the anterior papillary muscle, let us distinguish 4 types of septomarginal trabecula (I, II, III, IV). The most common was type III, the undivided trabecula, tightly connecting with the anterior papillary muscle. CONCLUSIONS: Based on the results of the following study we propose a hypothesis on the genesis of respective parts of the septomarginal trabecula and a plausible sequence of changes they undergo during human ontogenesis and phylogenesis of the primates.

Short history of the autopsy. Part I. From prehistory to the middle of the 16th century.

We present the first part of work concerning the history of autopsy. During the development of the pathology the role of autopsy was changing. The attitude towards the human body was often a result of struggles between human will to learn and religious beliefs. The knowledge was built upon religious procedures (mummification) through medical and surgical care of the victims of fights and wars and first autopsies. Until the 13th century dissections were seldom performed, sometimes in public. The aims varied from strictly scientific and practical (surgery) to artistic (human body in arts). Later on physicians were learning how to draw conclusions from autopsy results including malformations, pathologies, diseases, causes of death in order to try to put right diagnoses.

The crista supraventricularis in the human heart and its role in the morphogenesis of the septomarginal trabecula.

The crista supraventricularis and septomarginal trabecula are common elements of the right ventricle, and determine many hemodynamic phenomena. The morphological analysis of both structures in regard to their mutual relations was the aim of this study. The study was carried out on the material of preserved human hearts--fetuses, children and adults. The size and development of the crista supraventricularis was carefully evaluated. The division of its lower part, and hence the possibilities of development of the septomarginal trabecula, was divided into five types (A, B, C, D and E). The most common was type B, containing two muscular trabeculae. The width of the crista varied 1/5-3/5 of the width of the interventricular septum. On the basis of this study, a conclusion of morphological unity of the septomarginal trabecula and crista supraventricularis was drawn.

Remarks on the morphology of the papillary muscles of the right ventricle.

In addition to the papillary muscles of right ventricle referred to in anatomical nomenclature, namely the anterior, posterior and septal, we have distinguished the "conal papillary muscle" and the "papillary muscle of the posterior angle of the right ventricle". The conal papillary muscle was described by Luschka in the 17(th) century as the most constant of the septal papillary muscles. We have distinguished the muscles of the posterior angle of the right ventricle as muscles which would not be clearly classified as either septal or posterior muscles. Moreover, the muscles of the posterior angle of the right ventricle are probably associated with the transfer of the papillary muscles from the septum to the posterior wall of the right ventricle during phylogenetic evolution. Some researchers have classified them with the septal papillary muscles, while others have assigned them to the posterior group. The morphology of the muscles was classified using earlier categories for the posterior papillary muscles only. We have adopted the concept of multi-apical and multi-segmental muscles.

Unusual anatomical features of the right atrioventricular valve.

Despite the great interest taken in the tricuspid valve, the anatomical literature on the subject still leaves much open to question. The aim of this study was to describe the natural foramina which are present in the leaflets of the tricuspid valve, as well as, well -- founded onto -- and phylogenetically lack of continuity of its attachment and the frenula of the tricuspid valve. We studied the frequency of occurrence and morphology of these features of the tricuspid valve in 107 adult hearts.

Notes on the morphology of the tricuspid valve in the adult human heart.

Rapid progress in the field of interventional cardiology has caused research in the field of morphometry of the heart to be in constant demand. In this study, performed on a group of 75 adult human hearts, the authors have attempted to assess the form and number of the main and accessory cusps in the tricuspid valve. We have classified particular forms into 8 groups, depending on the number of cusps and we have divided the cusps into 3 main groups, depending on the support of the chordae tendineae.

Distribution of muscular bridges in the adult human heart.

UNLABELLED: Muscle bridges (MBs) are structures consisting of heart muscle tissue which pass above the coronary arteries and their branches. Although there are a relatively large number of descriptions of these MBs, researchers do not share a common view of the frequency of their occurrence, their location and their morphology, which remain the most controversial questions. The present research was carried out on 300 human hearts, adults of both sexes (161 male and 139 female), of between 21 and 76 years of age (mean age 48 years), in which no macroscopic developmental failures had been found. The hearts were preserved in formalinethanol solution. Selected coronary arteries were analysed. Images were examined of the perpendicular dissection of the coronary arteries and their neighbouring structures. On the basis of the analysis, the frequency of occurrence of MBs was defined as 31.3%. Muscular bridges were observed most frequently over the anterior interventricular branch of the left coronary artery (RIA) and, more rarely, over the right marginal branch of the left coronary artery (Rmd) and the circumflex branch of the left coronary artery (RCX). Using as criteria the number of muscular bridges in the heart and their location over particular coronary arteries, 4 types of configuration were established. With reference to the RIA, most MBs were located in the central part. We did not notice the same regularity with reference to other coronary arteries, nor did we observe MBs over coronary veins. CONCLUSIONS: muscular bridges are frequently observed structures in human hearts, most often seen over the anterior interventricular branch of the left coronary artery (RIA), mainly over its central segments, and occasionally over other arteries. MBs may occur in the heart singly or in a greater number and are found over the same or different vessels.