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.     

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.     

Rudimentary Coronary Artery in Syrian Hamsters (Mesocricetus auratus)

Congenital underdevelopment of one or more main branches of the coronary arteries has been reported in man, but not in non-human mammals. In man, this defective coronary artery arrangement may cause myocardial ischaemia and even sudden death . The main goal of this study was to describe the coronary artery distribution patterns associated with the presence of a markedly underdeveloped (rudimentary) coronary artery in Syrian hamsters. Moreover, an attempt was made to explain the morphogenesis of these patterns, according to current knowledge on coronary artery development. Eleven affected hamsters belonging to a laboratory inbred family were examined by means of internal casts of the heart, great arterial trunks and coronary arteries. The aortic valve was tricuspid (normal) in seven hamsters and bicuspid in the other four. A rudimentary coronary artery arose from the right side of the aortic valve in four specimens, from the left side of the aortic valve in a further three, and from the dorsal aortic sinus in the remaining four. In all cases, a second, well-developed coronary artery provided for all the coronary blood flow. Except for the existence of a rudimentary coronary artery, the present anomalous coronary artery distribution patterns are similar to coronary artery patterns reported in Syrian hamsters, dogs and humans in association with a solitary coronary ostium in aorta. We suggest that an unusual prolonged time interval in the development of the embryonic coronary stems might be a key factor in the formation of coronary arteries displaying significantly dissimilar developmental degrees.     

Morphology of Coronary Ostia in Domestic Shorthair Cat

Diagnosis and treatment of heart diseases due to changes in the coronary vascularization need a detailed knowledge on the morphology and possible variations of the aortic valves and coronary ostia. This study was performed to clarify details on morphology of these structures in domestic cats. The tricuspid aortic valve was examined in 65 domestic shorthair cats. The location of coronary ostia was determined either inferior to (26 and 20%, left and right coronary ostium – LCO and RCO), at (65 and 66%) or superior to the intercommissural line (9 and 14%). In 13 cats (20%), accessory ostia were found either for left, right or both coronary arteries (LCA and RCA). Their position varied between specimens. They were located beyond the main ostium, at its edge, or inside just below the edge. In one cat, no main trunk of the LCA was found. In one cat, two accessory ostia next to the RCO were observed. Coronary ostia in cats show anatomical variants and morphological anomalies. This study provides basic data useful for, for example, angiography performed for diagnosis of cardiac diseases and as a basis for surgical interventions.     

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.     

The right coronary artery is absent in the chinchilla (Chinchilla lanigera)

A total of 10 adult, healthy, male chinchillas (Chinchilla lanigera) were used to investigate the origin, course, and termination of the coronary arteries. Coloured latex was injected into the carotid arteries following conventional anatomical applications. In all the chinchillas examined, the left coronary artery was the single coronary artery. The right coronary artery was missing. Additionally, a small vessel originating from the cranial border of the aorta was observed in one chinchilla. The left coronary artery divided into the paraconal, interventricular and left circumflex rami. The left marginis ventricular ramus arose from the paraconal interventricular ramus in eight chinchillas, and from the left circumflex ramus in two. The ventricular and septal branches of the left coronary artery ran subepicardially at the beginning mostly parallel to the muscle fibres, also surrounded by a thin adipose tissue. It was concluded that the only left coroner artery supplied blood to the heart in the chinchilla.     

Non‐electrocardiographic‐gated computed tomographic angiography can be used to diagnose coronary artery anomalies in Bulldogs with pulmonary valve stenosis

Coronary artery anomalies have been reported in Bulldogs and present an increased risk when performing balloon valvuloplasty. Identification of coronary anomalies has been reported using multidetector‐row computed tomographic (MDCT) angiography with electrocardiographic gating. However, the utility of non‐electrocardiographic‐gated 16‐row computed tomographic for MDCT for the identification of coronary artery anatomy or anomalies to the authors’ knowledge has not been fully investigated. The purpose of this study was to evaluate the feasibility of non‐electrocardiographic‐gated computed tomographic (CT) angiography to identify coronary anomalies in Bulldogs with pulmonary valve stenosis. In this prospective, observational study, Bulldogs with echocardiographically diagnosed pulmonary valve stenosis, an echocardiographically derived transpulmonic pressure gradient >70 mm Hg, and a clinician recommendation for balloon valvuloplasty were included. Anesthetized dogs underwent a 16‐row MDCT non‐electrocardiographic‐gated CT angiography. A board‐certified veterinary radiologist and board‐certified veterinary cardiologist reviewed the CT angiography studies and identified the coronary artery anatomy. When normal coronary artery anatomy was detected on CT angiography, a right ventricular outflow tract fluoroscopic angiogram was performed and evaluated during levophase to confirm normal coronary anatomy prior to balloon valvuloplasty. Dogs with coronary anomalies noted on CT angiography were recovered from anesthesia and balloon valvuloplasty was not performed. All dogs (10/10; 100%) had interpretable images from the non‐electrocardiographic‐gated CT angiography. Coronary anomalies were identified in six dogs based on non‐electrocardiographic‐gated CT angiography, five with type R2A anomaly and one had a single left coronary ostium. Four dogs had normal coronary anatomy based on non‐electrocardiographic‐gated CT angiography. Balloon valvuloplasty was performed without incident in these four dogs. We conclude that non‐electrocardiographic‐gated CT angiography represents a noninvasive method for diagnosing coronary anomalies in Bulldogs with pulmonary valve stenosis.     

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.     

Pulmonic stenosis caused by single coronary artery in dogs: four cases (1965-1984)

Single right coronary artery (CA) associated with pulmonic stenosis was found in 3 English Bulldogs and a Boxer, suggesting a genetic predisposition for the associated anomalies. The left main coronary branch arose from the single right CA, encircled the pulmonic root over hypoplastic pulmonic valves at the level of the obstruction, and appeared to be the primary cause of underlying pulmonic stenosis. Patch-graft surgery to relieve pulmonic stenosis caused death in 1 dog when the unrecognized anomalous CA was served during the procedure. The anomalous left CA was detectable by use of angiocardiography in all 4 dogs and was recognized before surgery in 2 of them. In 1 dog, a right ventricle-to-pulmonary trunk-bridging conduit was implanted to improve outflow from the right side of the heart.     

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.     

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.     

Idiopathic extramural coronary arteritis in beagle and mongrel dogs

Hearts obtained from 119 toxicological experiments on dogs during a 21-year period (1965-1986) were evaluated histologically to determine the incidence and characteristics of focal microscopic inflammatory lesions of the extramural coronary arteries. Lesions were encountered in 23% of 119 experiments. The average overall incidence was 2.3% of 1,905 control and chemically treated male and female beagle hearts (3.1% of male and 1.3% of female control beagles, and 1.8% of male and 2.8% of female treated beagles). Lesions were seen in 4.7% of 127 random-source mongrel dogs. Histologically, lesions were characterized by adventitial infiltrates of mononuclear cells, areas of mural necrosis, and inflammatory cell infiltrates in both mural and subendothelial regions. In the latter region, fibrosis developed separating the intima from the internal elastic membrane. Lesions occurred in the right and left coronary arteries and in the dorsal, circumflex, and ventral descending branches of the left coronary artery. Vascular lesions were not present in the intramural coronary vessels or in vessels of other organs in affected animals. More extensive sampling of the extramural coronary arteries revealed an incidence of 5-9%. The lesion of focal extramural coronary arteritis was idiopathic, and not a manifestation of the polyarteritis syndrome of dogs.     

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.     

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.     

Left coronary aneurysmal dilation and subaortic stenosis in a dog

A 6-month-old German shepherd dog was referred for evaluation of a cardiac murmur.Upon physical examination, the auscultated heart rate was 120 beats/min, and a grade IV/VI systolic heart murmur with a point of maximal intensity over the left heart base radiating up the neck was heard. The standard echocardiographic examination showed subaortic stenosis and an anechoic tubular structure extending from the sinus of Valsalva to the left ventricular posterior wall. Aneurysmal left coronary artery (CA) was confirmed by angiography. The dog was euthanized and post-mortem examination showed severe dilatation of the proximal left CA and confirmed the subaortic stenosis. Histopathology did not demonstrate abnormalities in the walls of the CA, aorta or pulmonary artery.The exact cause of the CA aneurysmal dilation remains unknown. Subaortic stenosis, elevated coronary vascular resistance or a congenital anomaly may have contributed to the dilation.To our knowledge, coronary aneurysmal dilation has never been described in dogs. Standard echocardiography provides reliable information on coronary anatomy.     

Arteriolar nephrosclerosis in the Syrian hamster

Syrian hamsters developed spontaneous renal lesions that resembled those of arteriolar nephrosclerosis in man, and differed from other spontaneously occurring or virus-induced renal diseases in other rodent species. Morphologic changes were mainly degenerative with little cellular exudation and were associated with histologic changes in the intrarenal vasculature. The renal lesions were progressive, often fatal and sometimes were complicated by glomerular amyloidosis with the nephrotic syndrome and uremia. Endstage kidneys often had fibrinoid necrosis of intrarenal arterioles and thus resembled lesions characteristic of the malignant phase of human essential hypertension. Fibrinoid necrosis of small arterioles was common in the uterus, ovaries or testes of affected animals; it was less frequent in mesenteric or coronary vessels. Cardiac thrombosis, often involving the left atrium or left atrioventricular valves, also was common. Changes occurred earlier and often were more severe in females than in males. This disease was a major cause of morbidity and mortality and hampered life-span studies.     

Right coronary artery to left ventricle coronary cameral fistula in a cat

A six-month-old female intact domestic shorthair cat was presented for evaluation of a loud heart murmur. Transthoracic echocardiography revealed dilation of the left ventricle secondary to an abnormal vessel shunting blood into the left ventricular outflow tract at a high velocity during diastole. Multidetector computed tomography angiography revealed a coronary cameral fistula that originated at the right coronary artery, encircled the heart, and then terminated into the left ventricular outflow tract. This case report documents the first known case of a coronary cameral fistula in a cat. Multimodal imaging was an essential aspect to diagnosing the congenital lesion in this case.     

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.     

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) in four calves

Anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA), or Bland-White-Garland syndrome, is a rare congenital malformation described in children and adults. In this condition, the left coronary artery, which normally originates from the left coronary sinus in the aorta, instead originates from the pulmonary trunk, which results in retrograde flow of blood away from the myocardium into the lower-pressure pulmonary artery. Myocardial hypoxic-ischemic injury results in cardiac dysfunction, failure, and eventually in patient death if not surgically repaired. This report describes gross and microscopic findings in 4 beef calves with ALCAPA. All the calves had a history of being found dead with few or no premonitory signs, 2 shortly after sudden strenuous exercise. Gross necropsy lesions suggestive of heart failure included cardiomegaly with atrial and ventricular dilation and/or ventricular hypertrophy, and hepatomegaly. Dissection of each heart revealed the origin of the left coronary artery arising in the pulmonary trunk above the anterior cusp of the pulmonic valve. No degeneration; mineralization; and fiber loss, with replacement by fibrous connective tissue, predominantly in the left ventricular papillary muscle and the interventricular septum. Changes observed in the liver and lungs, including hepatomegaly, sinusoidal congestion, centrilobular fibrosis, and pulmonary congestion, edema, and intra-alveolar pigment-laden macrophages were consistent with heart failure.