Aberrant right subclavian artery causing megaoesophagus in three cats

Three entire, domestic, shorthair male cats (age range: 3 months to 5 years) were referred because of regurgitation. Megaoesophagus attributable to aberrant right subclavian artery, originating from the aorta at the level of the fourth intercostal space, was diagnosed in all cats using thoracic radiography and CT angiography. One cat had concurrent patent ductus arteriosus with a normal aortic arch. Three‐dimensional volume‐rendered CT images were used to assess the malformations and to plan surgery for the treatment of the vascular anomalies. Different surgical approaches were used in the two kittens. The third cat was not operated. CT angiography is well suited for preoperative planning in cats with aberrant right subclavian artery alone or in combination with other vascular anomalies.     

Persistent right aortic arch in a yearling captive wood bison (Bison bison athabascae).

An undersized, 16-mo-old, captive wood bison (Bison bison athabascae) was observed with dysphagia and postprandial regurgitation. The animal died shortly after anesthesia was initiated for diagnostic purposes. At necropsy, a persistent right aortic arch and aberrant left subclavian artery were diagnosed. The vascular ring structure around the esophagus and the trachea caused a megaesophagus with complete esophageal obstipation and ulcerative esophagitis. The aberrant left subclavian artery did not significantly compromise the esophagus. Persistence of the right aortic arch is relatively rare in ruminants and has not previously been reported in a bison.     

Unusual vascular ring anomaly associated with a persistent right aortic arch in two dogs

An unusual vascular ring anomaly consisting of a persistent right aortic arch and a left ligamentum arteriosum extending from the main pulmonary artery to an aberrant left subclavian artery and left aortic arch remnant complex was identified in a German shepherd dog and a great Dane. The left subclavian artery and left aortic arch remnant complex originated at the junction between the right distal aortic arch and the descending aorta and coursed dorsal to the oesophagus in a cranial direction. The attachment of the ligamentum arteriosum to the aberrant left subclavian artery was approximately 5 cm cranial to the point of origin of the aberrant left subclavian artery and left aortic arch remnant complex from the descending aorta in both dogs. This anomaly observed in both dogs is similar to an anomaly reported in humans, in which a persistent right aortic arch is found in conjunction with an aberrant left subclavian artery and a left aortic arch remnant (Kommerell's diverticulum). Surgical ligation and division of the left ligamentum arteriosum in both dogs, along with division of the left subclavian artery in the great Dane, resulted in resolution of clinical signs in both of the dogs in this report.     

Unusual Combination of Multiple Vascular Anomalies in a German Shepherd Puppy with Megaoesophagus

A 2‐months‐old male German shepherd puppy was referred for regurgitation and delayed growth. Radiographic and endoscopic investigations revealed a precardiac megaoesophagus and oesophageal constriction at the level of the heart base. At post‐mortem examination, a specific form of persistent right aortic arch characterized by an aberrant left subclavian artery in combination with a ligamentum arteriosum originating at the aberrant left subclavian artery (PRAA‐SA‐LA) was detected. A complete‐type persistent left cranial vena cava (PLCVC) was also observed. This is the first report describing the association between PRAA‐SA‐LA and PLCVC in a dog with megaoesophagus.     

Persistent right aortic arch and aberrant left subclavian artery in a white Bengal tiger (Panthera tigris).

A 3-mo-old male white Bengal tiger (Panthera tigris) presented with the chief complaint of regurgitation of solid food since weaning at 2 mo of age. Compared with its littermates, the tiger was in poor body condition and weighed only 10.3 kg when its littermates were estimated at 20-25 kg. Thoracic radiographs showed a megaesophagus cranial to the heart base. A contrast esophagram more clearly outlined the megaesophagus, and fluoroscopy demonstrated normal motility of the caudal esophagus. Endoscopic examination revealed a structure coursing dorsally from right to left over the esophagus and a constrictive band on the left of the esophagus at the heart base. Nonselective angiography confirmed the presence of a persistent right aortic arch, as well as an aberrant left subclavian artery. A left fourth intercostal thoracotomy was performed, and the ligamentum arteriosum was double ligated and divided. The left subclavian artery did not cause significant compromise of the esophagus and was not manipulated at surgery. The tiger recovered well from anesthesia and surgery. Solid food was slowly introduced over a 2-mo period without any regurgitation. The cub gained weight rapidly after surgery.     

Use of 3D printer technology to facilitate surgical correction of a complex vascular anomaly with esophageal entrapment in a dog

A 10 week old female intact Staffordshire terrier was presented with a total of five congenital cardio-thoracic vascular anomalies consisting of a patent ductus arteriosus (PDA) with an aneurysmic dilation, pulmonic stenosis, persistent right aortic arch, aberrant left subclavian artery and persistent left cranial vena cava. These abnormalities were identified with a combination of echocardiogram and computed tomography angiography (CTA). The abnormalities were associated with esophageal entrapment, regurgitation, and volume overload of the left heart with left atrial and ventricular enlargement. A 2 cm diameter aneurysmic dilation at the junction of the PDA, right aortic arch and aberrant left subclavian artery presented an unusual surgical challenge and precluded simple circumferential ligation and transection of the structure. A full scale three dimensional model of the heart and vasculature was constructed from the CTA and plasma sterilized. The model was used preoperatively to facilitate surgical planning and enhance intraoperative communication and coordination between the surgical and anesthesia teams. Intraoperatively the model facilitated spatial orientation, atraumatic vascular dissection, instrument sizing and positioning. A thoracoabdominal stapler was used to close the PDA aneurysm prior to transection. At the four-month postoperative follow-up the patient was doing well. This is the first reported application of new imaging and modeling technology to enhance surgical planning when approaching correction of complex cardiovascular anomalies in a dog.     

Hypoplastic aberrant left subclavian artery in a dog with a persistent right aortic arch

Vascular ring anomalies (VRA) are relatively uncommon cardiovascular disorders in canine patients. The most common VRA is a persistent right aortic arch (PRAA) with a left ligamentum arteriosum, however various other vascular anomalies resulting in tracheoesophageal compression have also been reported. We report a case of a dog with a PRAA and left ligamentum arteriosum with a hypoplastic aberrant left subclavian artery resulting in asymmetric cervicobrachial circulation. Selective angiography and ECG-gated multi-detector computed tomography were utilized in the evaluation of these defects. The case presented represents a unique vascular anomaly of the aortic arch not previously described in veterinary medicine.     

Subgross investigation of vessels originating from arcus aortae in guinea-pig (Cavia porcellus)

The vessels that originate from the aortic arch were studied in 16 adult guinea-pigs. Two major vessels, the left subclavian artery and the brachiocephalic trunk, were easily identified as they were branching off from the aortic arch. The brachiocephalic trunk, at first branched off to the left common carotid artery and continued as a common trunk, which was then divided into the right subclavian artery and the right common carotid artery. The left subclavian artery branched off to the following vessels: the costacervical trunk, the internal thoracic artery, a common trunk from which the dorsal scapular artery and the vertebral artery originated, and the superficial cervical artery. The right subclavian artery branched off to the bronchoesophageal artery (in five cadavers), the caudal thyroid artery (in three cadavers) and the tracheal artery (in three cadavers) in addition to the above vessels. There were two vertebral arteries branching off to the right subclavian artery in all dissected cadavers. However, only 10 cadavers had two vertebral arteries originating from the left subclavian artery. The first vertebral artery originated from the common trunk, whereas the second vertebral artery arose from the dorsal scapular artery. The second vertebral artery entered the foramen transversarium of the seventh cervical vertebrae and anastomosed with the first vertebral artery just before entering the foramen transversarium of the sixth cervical vertebrae.     

Surgical management of an aberrant left subclavian artery originating from a left patent ductus arteriosus in a dog with a right aortic arch and abnormal branching

An increase in the availability of advanced imaging modalities has led to improved recognition of cardiovascular anomalies. Computed tomography angiography (CTA) provides a non-invasive means of acquiring 3D images with a relatively short acquisition time thereby providing essential information in regards to patient anatomy and procedure planning. The dog in this report had a right aortic arch and abnormal branching with an aberrant left subclavian artery originating from the ampulla of a left patent ductus arteriosus (PDA) that was detected with CTA. The PDA was creating a volume overload to the left side of the heart as well as contributing to the vascular ring and compression of the esophagus. Therefore, ligation and transection instead of a minimally invasive catheter-based procedure was required. This aortic arch anomaly and surgical management have not been previously reported in dogs.     

Unusual vascular ring anomaly associated with a persistent right aortic arch and an aberrant left subclavian artery in German pinschers

The objective of this study was to describe a specific form of persistent right aortic arch (PRAA) in three German pinscher dogs and to analyse the mode of inheritance in the breed. This type of PRAA is characterised by a left retro-oesophageal subclavian artery in combination with a ligamentum arteriosum originating at the aberrant left subclavian artery (PRAA-SA-LA). This rare combination of anomalies has only been reported in two isolated cases in other dog breeds and the occurrence of any form of PRAA was not previously known to occur in the German pinscher. In the present study, 18 cases of this congenital anomaly were ascertained and their high degree of relatedness and inbreeding could be shown through pedigree analysis. Three of the affected dogs underwent further clinical investigations, and post-mortem examination (two cases) and findings at surgery (one case) verified the diagnosis of PRAA-SA-LA. A monogenic autosomal recessive mode of inheritance was not likely.     

Subgross and macroscopic investigation of blood vessels originating from aortic arch in the chinchilla (Chinchilla lanigera)

A total of 10 adult, healthy, male chinchilla (Chinchilla lanigera) were used to investigate the vessels originating from aortic arch. Coloured latex was injected into the carotid arteries following conventional anatomical applications in all the chinchillas examined. The brachiocephalic trunk and the left subclavian artery arose from the aortic arch at the level of the second intercostal region in the thoracic cavity. The right and left subclavian arteries detached branches at the level of first intercostal region and divided into the following vessels: internal thoracic artery, dorsal scapular artery, vertebral artery, superficial cervical artery and axillar artery. The vessels originating from the aortic arch displayed some significant differences in chinchillas compared to rats, guinea pigs, rabbits, porcupines and other laboratory rodents.     

Aberrant migration and surgical removal of a heartworm (Dirofilaria immitis) from the femoral artery of a cat

A cat was evaluated for an acute‐onset of right pelvic limb paresis. Thoracic radiographs revealed normal cardiac size and tortuous pulmonary arteries. Abdominal ultrasound identified a heartworm (HW) extending from the caudal abdominal aorta into the right external iliac artery and right femoral artery. The cat was HW‐antigen positive. Echocardiography revealed a HW within the right branch of the main pulmonary artery and evidence of pulmonary hypertension. An agitated‐saline contrast echocardiogram revealed a small right to left intracardiac shunt at the level of the atria. Surgical removal of the HW was performed with no substantial postoperative complications. There was return of blood flow and improved motor function to the limb. The cat remains mildly paretic on the affected limb with no other clinical signs.     

IMAGING DIAGNOSIS—COMPUTED TOMOGRAPHIC ANGIOGRAPHY CHARACTERISTICS OF MULTIPLE VASCULAR ANOMALIES IN A SENIOR DOG WITH LATE‐ONSET REGURGITATION

A 10‐year‐old dog weighing 3.4 kg presented with intermittent regurgitation. Esophagography revealed that the thoracic esophagus was compressed dorsally at the region of the fourth intercostal space and segmentally dilated from the second to third intercostal region. Three‐dimensional computed tomographic (CT) angiography confirmed a suspected vascular ring anomaly and also revealed multiple other vascular anomalies. These included aberrant right subclavian artery, absence of bilateral external jugular veins, right‐gastric caval shunt, and a completely duplicated caudal vena cava. Findings supported the use of thoracic CT angiography to rule out additional vascular malformations in dogs with suspected vascular ring anomaly.     

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.     

Three cases of aberrant right subclavian artery in the dog

In the normal dog only 2 arteries leave the ascending aorta–the brachiocephalic trunk and the left subclavian artery. This communication describes 3 dogs, a labrador, a poodle and a german shepherd, in which 3 large arteries left the ascending aorta–firstly a trunk for both common carotid arteries, then a left subclavian artery and finally a right subclavian artery.     

Branching pattern of aortic arch in the Korean water deer

This study examined the branching pattern of the aortic arch and its major branches in Korean water deer (Hydropotes inermis argyropus, Heude, 1884). Silicone casts were taken from the vessels of 23 carcasses (male 14, female 9) with body weights ranging from 1.3-16.0 kg through a retrograde injection into the abdominal aorta. The findings were compared with those from other domestic ruminants. Only the brachiocephalic trunk (Bct) branched from the aortic arch in all carcasses. In 19 of the 23 cases, the Bct branched into the left subclavian artery (LSb), the left common carotid artery (LCc), and then trifurcated into the right common carotid artery (RCc), right costocervical trunk (RCct) and right subclavian artery (RSb). The subclavian artery (Sb) branched into the costocervical trunk (in left), internal thoracic artery (It), and superficial cervical artery (Sc) in that order, and continued as the axillary artery. Instead of separated carotid arteries, the bicarotid trunk from the Bct was observed in only three males and one female. Two of these males had different branching orders of the It and Sc from the Sb in one or both sides. The other male had a RCct from the RSb. The left costocervical trunk (LCct) arose from the LSb in all cases, and branched into the highest intercostal artery, the dorsal scapular artery, and the deep cervical arteries in that order, and continued as the vertebral artery. In 22 cases, the RCct branched directly from the Bct at the same point in which the RCc (or bicarotid trunk) and RSb separated. The artery branching pattern from the RCct was similar to that of the LCct. These results suggest that the Korean water deer has a Bct with different branching patterns from those of domestic ruminants.     

Double aortic arch in a Siamese cat.

A double aortic arch is described in an 8-week-old female Siamese cat. In this case a vascular ring anomaly consistent with a double aortic arch is described in a cat. Stridor and dysphagia were noted in the cat. Radiography showed an esophageal dilation, with constriction at the fifth intercostal space. At necropsy, the esophagus and trachea were constricted at the base of the heart. The cause of the constriction of both the esophagus and trachea was a vascular ring formed by well-developed right and left aortic arches. The ascending aorta divided into two asymmetrical arches. The right aortic arch was larger than the left. The origin of the major arteries from the aortic arches were anomalous.     

Unilateral shunt formation with thoracic aortic dissection in a whippet

A three‐year‐old neutered male whippet was presented with intermittent, exercise‐induced paraparesis. Femoral pulses were bilaterally absent. Neurologic examination was suggestive of a thoracolumbar myelopathy. Blood pressure measurements revealed hypotension in both pelvic limbs, hypertension in the right thoracic limb and it was immeasurable in the left thoracic limb. Echocardiography was within reference limits. A clear vascular pulsation was palpable on the right ventral abdominal wall. Computed tomographic angiography revealed a dissection of the aortic wall between the left subclavian artery and the brachiocephalic trunk with subsequent thrombus formation. A shunt between the right internal thoracic, cranial and caudal epigastric arteries to preserve blood flow to the pelvic limbs was visualized. Necropsy was declined by the owner. This is the first case report describing the formation of a unilateral vascular shunt following a thoracic aortic occlusion, which presented as exercise‐induced paraparesis .     

Surgical correction of an aberrant right subclavian artery in a dog

A diagnosis of an aberrant right subclavian artery was made in a 3-month-old Boston terrier. Surgical correction was performed after confirming adequate collateral circulation. Reports of surgical correction and evaluation of the perioperative thoracic limb blood pressure are rare in dogs.     

Double aortic arch in a dog (Canis familiaris): a case report

We herein report a case of a double aortic arch in a 10-week-old male dog of no defined race, which presented episodes of regurgitation at the time of weaning. This vascular malformation was characterized by the persistence of two aortic arches, right and left, of varying dimensions. The right aortic arch was observed to be larger. During post mortem examination the vessels of the animal were injected with coloured latex bi-centrifuged CIS 1-4 polisopreno which revealed the patency of the two aortic arches. Concomitantly, dilation of the cranial oesophagus causing constriction was observed, indicating megaesophagus. Apart from the constriction, the oesophagus presented normal morphometric parameters in relation to its dimensions.