Separate origin of the main components of the left coronary artery in Syrian hamsters (Mesocricetus auratus)

This study describes a rare congenital coronary artery anomaly in the Syrian hamster; namely, the separate origin of the obtuse marginal and left circumflex arteries which are the main components of the left coronary artery. The hearts of nine affected animals were examined by means of a corrosion-cast technique and histology. The hamsters belonged to a laboratory inbred family with a high incidence of coronary artery anomalies and bicuspid aortic valve. The aortic valve was tricuspid in three hamsters and bicuspid in the other six hamsters. In all cases, the right coronary artery was normal, whereas the left coronary artery main trunk was absent. The present anomalous coronary artery patterns could be classified into two main entities: (i) ectopic origin of the obtuse marginal artery from the right aortic sinus or from the right coronary artery, with the left circumflex artery arising from the left side of the aortic valve; and (ii) ectopic origin of both the obtuse marginal artery from the right aortic sinus or from the right coronary artery and left circumflex artery from the dorsal aortic sinus. In all cases, the obtuse marginal artery coursed to the right side of the heart through the ventral wall of the right ventricular outflow tract. When the left circumflex artery arose from the dorsal aortic sinus, it formed an acute angle with the aortic wall. This report seems to be the first to describe the separate origin of the main components of the left coronary artery in a non-human mammalian species. In man, the congenital coronary artery and aortic valve defects reported herein may entail the risk of clinical complications. However, none of the affected hamsters showed signs of disease.     

Number of coronary ostia in Syrian hamsters (Mesocricetus auratus) with normal and anomalous coronary arteries

Little attention is being paid to the presence of accessory coronary artery ostia in man and non-human mammals due to their limited clinical relevance. However, information about their frequency and the cardiac territories irrigated by the vessels arising from them is of interest to obtain an accurate survey of the establishment of the coronary artery system in each species. The aim here was to compare the incidence and significance of the accessory coronary ostia in Syrian hamsters with normal coronary arteries and several coronary anomalies characterized by the absence of a left coronary artery originating from the left aortic sinus. The hearts from 2829 hamsters were examined using a corrosion-cast technique, micro-dissection, histochemical techniques, and scanning electron microscopy. Overall, 148 specimens displayed accessory ostia. A limited number of them belonged to the conal artery which supplies the wall of the right ventricular outflow tract. The other accessory ostia led to the septal artery, a vessel which irrigates the most part of the interventricular septum. The incidence of accessory ostia in normal and anomalous coronary artery patterns was quite similar. This suggests that the morphogenetic deviations producing the coronary artery anomalies reported in this study do not alter the connections of the septal and conal arteries to the aorta. The present observations lead to the notion that in the Syrian hamster, the septal artery should be regarded as a third coronary artery.     

Fatal myocardial infarct in a Greyhound

Death is reported in a 3-year-old Greyhound due to an acute myocardial infarction, consequent upon thrombo-embolic occlusion of the left descending coronary artery, subsequent to dislodgement of a vegetative lesion of the left lateral aortic valve, secondary to sub-acute bacterial endocarditis. A comparison between some aspects of cardio-vascular disease in man and dogs is made, and the term ‘heart attack’ as used in the human condition is investigated and its legitimate application to veterinary conditions discussed. The main difference between human and animal coronary disease is the widespread occurrence of atherosclerosis in humans and its absence in animals.     

Absent Left Main Coronary Artery with Variation in the Origin of its Branches in a South African Population

Coronary artery anomalies are traditionally classified into anomalies of origin, course and termination. One of the anomalies of origin is absence of the left main coronary artery (LMCA), where the left anterior descending (LAD), the circumflex (Cx) and the ramus medianus (RM) (when present) arteries originate directly from the left aortic sinus. The study aimed to document the prevalence of absent LMCA, discuss its possible embryogenesis and clinical relevance. A review of 407 coronary angiograms performed by cardiologists of three private hospitals in the eThekwini Municipality area of KwaZulu‐Natal, South Africa, was performed. The LMCA was absent in 9.6% (39/407) of the coronary angiograms. The LAD and Cx arteries originated directly from the left aortic sinus with a single ostium in 8.6% (35/407) and separate ostia in 1% (4/407) of the angiograms. In four of the angiograms with absent LMCA, a RM artery was recorded originating directly from the left aortic sinus in addition to the LAD and the Cx arteries. Angiographic detection of the anomalies of the coronary arteries is essential in the determination of the significance of such findings and their management.     

Senile cardiac amyloidosis in the dog

Thirty-two cases of senile cardiac amyloidosis from a routine necropsy material of 594 dogs were studied. The age of the affected dogs ranged from 10 to 16 years. Amyloid was observed in the intramural arteries and arterioles, predominantly in the ventricular myocardium. The vessels were often obturated with amyloid, and myocardial necroses and fibroses were common consequences of the vascular lesions. In three cases amyloid deposits were also observed in the main subepicardial coronary arteries. In contrast to man, only slight interstitial amyloid degeneration was found in four of the dogs observed. Amyloid in the mitral valves, tricuspid valves and aortic cusps was observed in six, two and three cases respectively. It was concluded that the distribution of senile cardiac amyloidosis in the heart of the dog differs considerably from that in man.     

The arrangement of the coronary artery trunks is subject to inheritance factors: A study in Syrian hamsters

The concept that anatomical variations in the coronary artery tree might be influenced by genes is relatively old. However, empirical evidence on the effect of genotype on the coronary morphology is still scarce. In the Syrian hamster, there is a septal coronary artery which arises from the left or from the right coronary artery and supplies most of the interventricular septum. The aim was to decide whether the anatomical origin of the septal artery is subject to inheritance factors. Overall, 483 internal casts of the heart and coronary arteries were examined. All the hamsters included in this study had normal coronary arteries. The results of 74 crosses were compared statistically to seek for any significant difference between the phenotypes of the offspring and the phenotypes of the parents. The left septal artery was over‐represented in the offspring of crosses between parents having both a left septal artery (p < .01), while the right septal artery was over‐represented in the offspring of crosses between parents, one with a right and the other with a left septal artery (p < .001), and, more markedly, in the offspring of crosses between parents both with a right septal artery (p < .001). These results are the first to reveal that the coronary artery pattern is influenced by genetic factors, at least in its proximal portion with regard to the aorta.     

Coronary arteries of the roe deer (Capreolus capreolus; Linnaeus 1758) heart

A study of the coronary arteries of the roe deer heart was performed on 21 hearts of animals of both sexes and various ages. The roe deer heart is supplied by two arteries: the left coronary artery and the right coronary artery. The left coronary artery arises from the left aortic sinus and forms a short common trunk. The left coronary artery reaches the coronary groove, then divides into the paraconal interventricular branch and the circumflex branch. The circumflex branch gives off several branches to the left ventricle wall and terminates in the subsinuosal interventricular groove as the subsinuosal interventricular branch. The right coronary artery is less pronounced than the left coronary artery. It arises from the right aortic sinus and enters the coronary groove as the right circumflex branch. We found the left arterial cone branch in 75% and the right arterial cone branch in 80% of the cases investigated. The coronary arteries of the heart run subepicardially. In 9 cases we found muscular bridges over the coronary arteries, mostly on the paraconal interventricular branch. In conclusion we affirm the left type of the arterial vascularisation in the roe deer heart.     

Pathogenesis of single right coronary artery and pulmonic stenosis in English Bulldogs

English Bulldogs are the most common breed to have pulmonic stenosis. Previous studies showed that this congenital heart abnormality in Bulldogs frequently is caused by a circumpulmonary left coronary artery originating from a single right coronary artery. Fetal anasarca also occurs often in Bulldogs and might represent congestive heart failure, but the cause is unknown. To determine if fetal anasarca is associated with a coronary anomaly and pulmonic stenosis, major coronary arteries were studied in 6 bulldog puppies with fetal anasarca. Five of the puppies had normal coronary arteries, and this led to the conclusion that fetal anasarca usually is not associated with major coronary abnormalities or pulmonic stenosis. The 6th puppy had single right coronary artery with circumpulmonary left coronary artery and moderate subvalvular pulmonic stenosis. Serial section histology suggests that the underlying cause of this syndrome is malformation of the left aortic sinus (of Valsalva) and inversion of the proximal segment of the left main coronary artery.     

Anomalous Origin of the Coronary Arteries in Two Calves

Anomalities of the coronary arteries may include one or more of the following variations: abnormal number, abnormal course, or abnormal origin. Many of these anomalies have been described in man.⁽²⁸⁾ Anomalous origin of the left coronary artery from the pulmonary artery (A.O.L.C.A.) has been estimated ⁽¹⁹⁾ to occur in one of 300,000 children and to represent approximately 0.5% of all types of congenital heart disease. In a recent review⁽²⁸⁾ of these conditions in man, anomalous origin of the right coronary artery from the pulmonary artery (A.O.R.C.A.) had been reported 16 times, A.O.L.C.A. 39 times, and anomalous origin of both coronary arteries from the pulmonary artery (A.O.B.C.A.) 5 times.     

Spontaneous tumors in domestic hamsters

A total of 90 tumors from 85 domestic hamsters (70 Djungarian hamsters and 15 Syrian hamsters) were examined by histology. In the Djungarian hamsters, 64 neoplastic and 11 non-neoplastic lesions were identified, whereas 14 Syrian hamsters showed neoplastic disease, and one showed non-neoplastic disease. The Djungarian hamsters showed a high prevalence of neoplastic disease, similarly to laboratory Djungarian hamsters. In the Djungarian hamsters, almost all tumors were integumental, whereas hematopoietic tumors were the most common type in the Syrian hamsters. The most common integumental tumors in the Djungarian hamsters were mammary tumors, atypical fibromas and papillomas, and a spectrum of integumental tumors that have not been reported in laboratory Djungarian hamsters were identified. Most mammary tumors occurred in the females, whereas all atypical fibromas were observed in the males. In the Syrian hamsters, plasmacytomas and lymphomas were the most common tumors. The small number of Syrian hamsters in this study may reflect the low prevalence of spontaneous tumors seen in laboratory Syrian hamsters. The mean age of the affected hamsters was 19.8 months, which is relatively advanced. To our knowledge, this is the first comprehensive study of tumors in domestic hamsters.     

Macroscopic description of the coronary arteries in Swiss albino mice (Mus musculus)

A total of 25 (13 male, 12 female) adult, healthy Swiss albino mice were used to investigate the origin, course and anastomoses of coronary arteries. Coloured latex was injected into the aortic arch to enable these arteries to be clearly discerned. A. coronaria sinistra was larger than A. coronaria dextra. It was divided into a Ramus interventricularis paraconalis and a Ramus circumflexus sinister. However, in 2 specimens, the septal ramus, was observed to stem directly from the left coronary artery, and only 1 ventricular branch arose from the left circumflex. The collateral branches of the paraconal interventricular ramus had a larger diameter and more extensive distribution was observed in these specimens. The A. coronaria dextra was divided into a Ramus septalis and Ramus circumflexus dexter. The Ramus interventricularis subsinuosis was not detected in this study. The ventricular branches of the left coronary artery run intramyocardially whereas the branches of the right coronary artery course subendocardially.     

Collateral vessel development, following unilateral chronic carotid occlusion in the dog.

Because much of the data base describing the physiology of cerebral circulation is based on experiments using the dog as a model and because the functional response to occlusion of arteries supplying the head have been shown to be different in man than in dogs, it is important that the growth and development of the extracerebral collateral circulation in dogs be documented. Using the techniques of corrosion casting, collateral vessel development was evaluated in adult mixed-breed dogs, following 4- and 8-week periods of unilateral ligation of the common carotid artery or the external carotid artery. Neurologic deficits or severe ischemia was not observed in any of the dogs during the postoperative period. Extensive collateralization occurred between the ipsilateral vertebral artery, regardless of the occlusion site. In addition, numerous collateral connections developed between the same vessel from the contralateral side. Two main patterns of collateral vessel organization consistently developed. Initially, a collateral network of highly tortuous superficial vessels predominated. With longer survival times after occlusion, deeper and more uniform-diameter direct-collateral vessels developed.     

ECHOCARDIOGRAPHIC APPEARANCE OF FLAIL AORTIC VALVE IN A DOG WITH INFECTIVE ENDOCARDITIS

A 4-year-old female Boxer was suffering from aortic valve endocarditis with perforation of the right coronary cusp resulting in a flail aortic cusp and subsequent acute aortic insufficiency. This flail aortic cusp was observed on M mode and two-dimensional endocardiograms as a free linear echostructure in the left ventricular outflow tract. Although rarely observed, a free linear echostructure seems more specific of a flail aortic valve than a shaggy echostructure, which can represent a free moving vegetation and thus be confusing. Severe acute aortic insufficiency resulted in an uncommon abnormal mitral valve motion in the absence of early mitral diastolic opening. The absence of early mitral valve opening was thought to be a consequence of coupled aortic regurgitation, reduced left ventricular compliance, and presumably delayed mitral valve opening secondary to coronary artery occlusion. An exaggerated septal diastolic dip accounted for the decreased transmitral inflow. All the usual contractility parameters were within normal range; subsequently, mitral valve motion alterations seems to be more reliable indicators of left ventricular dysfunction during acute aortic insufficiency.     

Third coronary artery in monkey heart

Investigations were carried out on 55 monkey (Cercopithecus aethiops, Macaca fascicularis) hearts by stereomicroscopic dissection and measurements. Latex-injected specimens and corrosion casts showed that, as in humans, the hearts were usually (in 98.2% of the cases) supplied by two coronary arteries (CAs)--the left (LCA) and the right coronary artery (RCA), and occasionally (in 1.8% of the cases) also by a third one (TCA). Furthermore, the orifice of the TCA was situated in the right aortic sinus at the same level as the RCA and 0.2 mm in front of it. The LCA and the RCA originated from the corresponding aortic sinuses and the external diameter of the LCA was greater [average: 1.65+/-0.39 (SD) mm] than that of the RCA [average 0.94+/-0.15 (SD) mm] and the TCA (0.8 mm). The LCA orifice was more often above (76.3%) than below the free edge of the left aortic valve leaflet. The longitudinal axis of the aortic root and of the initial part of the LCA formed an angle of 45-120 degrees (average: 52 degrees). The orifice of the RCA was usually above (82.3%) the free edge of the right aortic valve leaflet, and less frequently below it (17.7%). The longitudinal axis of the aortic root and of the initial part of the RCA formed an angle of 70-150 degrees (average: 103 degrees). The resemblance of monkey CAs to their human counterparts make them a suitable model for experimental studies on coronary circulation.     

RUPTURE OF THE LEFT AORTIC SINUS INTO THE PULMONARY ARTERY IN A DALMATIAN DOG

An 18-month-old male Dalmatian dog was presented for veterinary evaluation after the pet owner observed a sudden onset of weakness. An acquired continuous cardiac murmur was detected on physical examination. Two-dimensional echocardiographic examination revealed structural abnormalities of the proximal aorta and pulmonic valve. Doppler echocardiographic studies and cardiac catheterization demonstrated the presence of a proximal aorticopulmonary shunt. A diagnosis of left aortic sinus rupture and aorticopulmonary fistula was made. Antemortem diagnosis of aortic sinus rupture in the dog has not, to our knowledge, been reported previously. The anatomical variant of left aortic sinus rupture resulting in the development of a fistula from the aorta to the main pulmonary artery is, apparently, uncommon in all species.     

Branching patterns of the left main coronary artery in the dog demonstrated by the use of corrosion casting technique

As many investigators use dogs as experimental models in catheterization-, ligation-, and collateral flow studies, knowledge and awareness of the canine left coronary artery anatomical variation is vital for differentiation between canine and human coronary arterial patterns and canine and human coronary congenital anomalies with or without circulatory importance. The present study was performed to examine and review the various principal subdivisions of the canine left main coronary artery (LMCA) in vascular casts of 20 hearts obtained from cadavers of clinically normal dogs of various ages, breeds and of either sex. A corrosion casting technique using an acrylic resin called Tensol Cement No. 70 and a lower-viscosity acrylic resin called Mercox were used to produce a three-dimensional model of the canine coronary arteries. In our study, all dog hearts were left preponderant and the patterns of the principal subdivisions of the LMCA were grouped into three types: Type 1 occurred in seven of the 20 dogs (35%), Type 2 in 12 of 20 dogs (60%) and Type 3 in one instance (5%). A comparison between the canine divisional patterns of the LMCA in the vascular casts and those reported in the literature showed major agreement.     

64‐MULTIDETECTOR COMPUTED TOMOGRAPHIC ANGIOGRAPHY OF THE CANINE CORONARY ARTERIES

Canine coronary artery angiography (CTA) was performed in four anesthetized healthy dogs using 64‐multidetector computed tomography. Esmolol, a β‐1 adrenergic receptor antagonist, and sodium nitroprusside, an arteriolar and venous dilator, were administered to enhance visualization of the coronary arteries by reducing heart rate and creating vasodilation. The left main coronary artery with its three main branches and the right coronary artery were visualized and subdivided in 13 segments for evaluation. Optimal reconstruction interval, expressed as percentage of the R‐to‐R interval, was determined at 5% in 2.9%, 35% in 1%, 75% in 21.2%, 85% in 43.3%, and 95% in 31.7% of the segments. Overall image quality was good in 41.3% of the segments and excellent in 14.4%. There was blur in 98.1%, motion in 17.3%, and stair step in 6.7% of the evaluated segments, but these artifacts did not interfere with anatomic depiction of the arteries. Cross‐sectional anatomy of the coronary arteries as evaluated from the coronary CTA agreed well with gross anatomic evaluation and published information. The use of esmolol did not lead to the target heart rate of 60–65 beats/min. Nitroprusside had no significant effect on visualized length or diameter of the coronary artery branches. Coronary CTA is useful for the anatomic depiction of coronary artery branches in the dog.     

Idiopathic arterial medial calcification of the thoracic arteries in an adult horse

A 6-year-old, gelded, Paint horse displayed clinical signs of muscle wasting and limb stiffness for a 6-month period. The horse's clinical signs abated with corticosteroid therapy, but returned upon cessation of treatment. Upon necropsy, severe lesions of aortic thickening and aortic valve rigidity were observed. Histologically, the tunica media of the aorta, coronary arteries, and pulmonary arteries were expanded by foci of elastin fiber calcification and extracellular matrix with lacunae formation. The vascular lesions are comparative to what has been described as medial arterial calcification, seen in humans suffering from chronic renal failure or diabetes mellitus. No exposure to vitamin D-containing plants or feedstuff could be documented at the time of onset or during the period of clinical signs. The current case describes dramatic lesions of arterial medial calcification of the aorta, coronary, and pulmonary arteries of undetermined cause.     

初生仔猪腹腔脏器的动脉分枝类型

用乳胶加颜料血管注射的方法,对32例初生仔猪的腹腔脏器的动脉分枝进行观察,其主要结果如下: 腹腔动脉有五个分枝类型,即两枝型(脾动脉、肝动脉)有25例(78.13％);三枝型(脾动脉、胃左动脉、肝动脉)有3例(9.36％);四枝型A(脾动脉、憩室动脉、胃左动脉、肝动脉)有1例(3.13％);四枝型B(两主枝是脾动脉和肝动脉,两侧枝是胃左动脉和憩室动脉)有1例(3.13％);一枝型(只有脾动脉,而肝动脉则来自肠系膜前动脉)有2例(6.25％)。 空肠动脉的分枝,依次形成初级弓、二级弓和网状丛,再由网状丛发出大量的、放射状的小枝分布到肠管上。这些小枝呈两两成对地并列(与同级静脉伴行),到肠管附近,两枝彼此分开,每枝分布到肠管的一个侧面。     

Microvasculature of the hamster eye: scanning electron microscopy of vascular corrosion casts

The architecture of the retina, choroid and anterior eye segment was investigated in 12 Syrian hamsters using scanning electron micrographs of methylmethacrylate corrosion casts. The hamster eye receives its primary blood supply from the long posterior ciliary artery, which directly enters the optic nerve head, and divides into three branches: the central retinal artery and medial and lateral long posterior ciliary arteries. In the retina the central retinal artery divides into six radiating branches. Retinal arterioles form a slender and long course to capillaries. Retinal capillaries are extremely thin in diameter and form a sparse capillary network. The choroid is supplied by the long posterior ciliary arteries. Choroidal arterioles exhibit a thick and short course to the choriocapillaris. The choriocapillaris is thick and sinusoid-like, forming a dense network in the choroid. The ciliary body, iris and bulbar conjunctiva are supplied by the anterior ciliary arteries, which are branches of the long posterior ciliary arteries. Capillaries supplying the anterior margin of the ciliary process are large in diameter with an irregular bore, forming a thoroughfare channel draining blood in the ciliary arterioles into the pars plana vessels. Blood from the retina is drained by the central retinal veins. Venules from the anterior eye segment empty into the vortex veins via the pars plana vessels. Venous blood from the choroid is drained only by vortex veins via the choroidal veins. The functional significance of the vascular architecture and species differences are discussed.