Aortic dissecting aneurysm associated with systemic arterial hypertension in a cat.

INTRODUCTION: Aortic dissection is characterized by a tear in the aortic wall resulting in blood from the aortic lumen penetrating into the media, which causes dissection. When aortic dissection does not cause rupture, it provokes localized dilation of the aorta or aneurism, also called dissecting aortic aneurism (DAA). This case report describes a DAA in a cat associated with systemic arterial hypertension (SAHT). A 10-year-old male Domestic shorthair cat was presented for cardiac evaluation. Anamnestic clinical complaints were a syncope associated with paraparesis and weak femoral pules. Cardiomegaly had been found radiographically, and cardiogenic arterial thromboembolism had been suspected. Upon presentation physical abnormalities were tachycardia and a heart murmur. Measurement of systolic systemic arterial blood pressure (SABP) revealed severe SAHT. Echocardiographic images showed severe DAA, and marked aortic valve insufficiency. Palliative antihypertensive treatment resulted in fast clinical improvement and significant decrease in blood pressure. Four months later, acute severe respiratory distress due to cardiogenic pulmonary edema led to the cat's euthanasia. In human medicine, DAA is a well-reported complication of SAHT. This is the second case of DAA with congestive heart failure reported in a hypertensive cat.

AORTIC ANEURYSM, DISSECTION, AND RUPTURE IN SIX BILE-FARMED BEARS.

Across China and Southeast Asia, over 17,000 bears are currently farmed for bile, predominantly for traditional Chinese medicines. Bears on farms in China are cage confined and undergo repeated daily bile extraction facilitated by surgically implanted catheters or gallbladder fistulas. Numerous health problems have been reported in bile-farmed bears including peritonitis, abdominal hernias, and extraction site abscessation. Between 2009 and 2014, five Asiatic black bears ( Ursus thibetanus) and one Asiatic black/Eurasian brown bear ( Ursus arctos arctos) hybrid, rescued from the bear bile industry in China, died from ruptured and/or dissecting aortic aneurysm. Medical records were reviewed and two bears exhibited no clinical signs prior to death. In four bears, clinical findings varied and included increased stereotypic behavior prior to death, epistaxis, retinal lesions, dysphagia, weight loss, and acute onset of hyporexia. On postmortem examination, hemopericardium with dissection and/or rupture of the ascending aorta and left ventricular wall hypertrophy were present in all cases. No evidence of infectious disease, connective tissue disorders, or congenital cardiac disease was identified. Based on these observations screening thoracic radiography was performed on all bears at the rescue center and aortic dilation was identified in 73 of 134 (54.5%) bile-extracted bears. To the authors' knowledge, aortic aneurysm, rupture, and/or dissection have not been previously reported in any bear species and the high prevalence in this population of bears suggests an association with bile-farming practices. Future studies are needed to investigate the etiopathogenesis of this condition to aid in early diagnosis and improved management of bears being rescued from bile farms across Asia.

Dissecting aortitis in a goat associated with Pasteurella multocida and Staphylococcus spp infection.

Reports of primary cardiovascular disease in goats are rare and most commonly include ventricular septal defect, valvular endocarditis, traumatic pericarditis, ionophore poisoning and nutritional cardiomyopathies. We now report the pathological findings in a 67 kg, 6-year-old, adult female Boer goat that presented with neurological signs (ie, head pressing, unsteadiness and paddling) and hyperthermia 2 days prior to death. Lack of therapeutic response to meloxicam and penicillin‒streptomycin and poor prognosis led to euthanasia of the animal. At necropsy, the main findings included severe aortic dissection with luminal thrombosis and stenosis, and pulmonary congestion and oedema. Histological examination of the aorta revealed severe chronic granulomatous and fibrosing dissecting aortitis with mineralization. Bacterial culture of the affected aortic segment resulted in isolation of a profuse growth of Pasteurella multocida and a moderate growth of Staphylococcus spp. Histopathological findings in the central nervous system were consistent with neurolisteriosis.

Spontaneous type A aortic dissection in a dog.

A 10-year-old male Cocker Spaniel was presented for evaluation of right forelimb lameness and seizure-like episodes. Panting with increased respiratory rate and opisthotonus were evident during the physical examination. Cardiac auscultation revealed a left basilar, grade III/VI systolic murmur. The dog was stabilized with diazepam, fluid therapy, and oxygen. Indirect arterial blood pressure measured in the left forelimb by Doppler technique revealed no abnormalities. Thoracic radiography indicated a noticeable bulge in the area of the ascending aortic arch. Transthoracic echocardiography revealed marked aortic dilatation with a mobile, floating tissue flap dividing the aorta into two lumens. Additional diagnostic studies (computerized tomography, cardiac catheterization, and angiography) were offered but not obtained. Medical management included therapy with enalapril and clopidogrel. Clinical signs, including the right forelimb lameness and seizures, resolved within 24 h. This report represents an unusual case of aortic dissection in a dog associated with neurological signs.

Pulmonary artery dissection following pulmonary balloon valvuloplasty in dogs.

INTRODUCTION/OBJECTIVES: Pulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. We sought to report the rate of this complication in dogs and describe the demographic, clinical, procedural, and outcome data in affected dogs. ANIMALS, MATERIALS AND METHODS: Medical records at a single academic institution between 2002 and 2021 were reviewed for dogs with pulmonic stenosis treated by a balloon valvuloplasty. Dogs were included for evaluation if there was evidence of pulmonary artery dissection on echocardiography or necropsy following balloon valvuloplasty. The demographic, clinical, surgical, and follow-up information were then recorded. RESULTS: Six dogs were included from 210 balloon valvuloplasty procedures for pulmonic stenosis giving a 3.9% rate of pulmonary dissection. There was a variety of signalment, pulmonary valve morphologies, and balloon catheter types used in each dog. All dogs had severe pulmonic stenosis (median pressure gradient of 208 mmHg, range 94-220 mmHg) with 5/6 dogs having a pressure gradient >144 mmHg. The median balloon to pulmonary valve annulus ratio was 1.35 (range 1.25-1.5). Three dogs died perioperatively, and three dogs were alive at follow up 3.3, 4.0, and 4.1 years postoperatively. CONCLUSION: Pulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. Extreme elevations in preoperative pulmonary valve flow velocity were common. Prognosis is variable, with a potential 50% perioperative survival rate, but extended survival times were noted in those patients discharged from hospital.

Persistent truncus arteriosus with dissecting aneurysm and subsequent cardiac tamponade in a lamb.

The present case report describes the necropsy and histopathology findings of a 3-week-old lamb with persistent truncus arteriosus (PTA). This rare cardiac malformation was characterized by the presence of a common arterial trunk arising from the right ventricle and overriding a ventricular septal defect. The pulmonary arteries originated from a short common trunk from this PTA, which subsequently continued as the thoracic aorta. The death of the lamb was attributed to a rupture of the PTA with subsequent cardiac tamponade. Histologically, a dissecting aneurysm with elastic fiber fragmentation in the wall of the PTA was identified as the underlying pathologic condition. Altered hemodynamic forces with subsequent secondary vasculopathy, as well as congenital primary vasculopathies, should be considered as an underlying pathogenetic mechanism.

Aortic dissection in four cats: clinicopathological correlations.

Aortic dissection (AD) is characterized by bleeding within the aortic wall or a tear in the intimal layer of the aortic wall, resulting in the passage of blood from the aortic lumen into the tunica media. In cases of AD, a floating, intimal flap in the aortic lumen divides the lumen into a true portion, with flow present, and a false portion, with no flow. We describe a series of 4 cats with AD of the ascending aorta and moderate aortic insufficiency. Three cats had an acute onset of clinical signs with pericardial effusion and cardiac tamponade, whereas one cat showed a chronic onset without pericardial effusion. Detailed gross and histopathological characterization is available for two cats, which revealed the typical features of AD. One cat also showed connective tissue abnormalities, microscopically resembling Marfan-like syndrome. Concomitant detection of hypertrophic cardiomyopathy in 2 cats represents a novel finding in the veterinary literature. Feline AD is generally associated with systemic hypertension. In all the cats of this case series, blood pressure was normal at presentation, although systemic hypertension before the acute dissection cannot be ruled out. In humans, hypotension is more common with AD of the ascending aorta, so the anatomical location could also play a role in cats. Hypertrophic cardiomyopathy in cats could have been a potential trigger of AD through shear stress. Transthoracic echocardiography, as herein demonstrated, can be considered as a rapid, non-invasive and useful method for the diagnosis of dissection at the level of the ascending aorta.

Left subclavian artery dissection associated with connective tissue abnormalities resembling Marfan-like syndrome in an English bulldog.

The unexpected demise of a 12-year-old male neutered English bulldog solicited a gross examination, which revealed a blood-filled space occurring in the proximal left subclavian artery (LSA). It originated about 1 cm from the branching point of the vessel and progressively dilated for 3 cm distal to this origin. Histopathological investigation showed that the tunica media of the LSA was more than 50% split, with the blood-filled space dissecting through the arterial wall. In the tunica media of the LSA, severe multifocal fragmentation and/or loss of the elastic fibers was observed. The retained disorganized elastic fibers were separated and disoriented due to accumulations of acid mucopolysaccharide. Marked, diffuse medial, and adventitial fibrous tissue deposition was also identified. The cause of death was attributed to acute hemorrhagic and necrotizing pancreatitis with pulmonary edema, suggesting that LSA dissection was an incidental finding. Subclavian artery dissection is extremely rare in humans, where the involvement of the LSA in cases of aortic dissection both with or without Marfan syndrome has been reported. Aortic and pulmonary artery dissection in bovines and aortic aneurysm and dissection in dogs have been reported to be associated with Marfan and Marfan-like syndromes, respectively. Histopathological findings suggestive of underlying connective tissue abnormalities resembling Marfan-like syndrome (i.e., the appearance of the elastic tissue and the degenerative changes of the tunica media) were detected in the first case of LSA dissection in dogs and veterinary medicine, herein described.

Pulmonary artery dissection causing haemothorax in a cat: potential role of Dirofilaria immitis infection and literature review.

A 7-year-old male castrated domestic short-haired cat suddenly died. Gross examination revealed severe right-sided haemothorax with blood clots, four adult filarial nematodes in the blood clots and the caudal vena cava and haemorrhage dissecting into the tunica media of the right pulmonary artery. Histopathological investigation showed fibrosis of the tunica intima and disorganization/fragmentation of the elastic fibres accompanied by fibrous tissue deposition in the tunica media of both branches of pulmonary artery. Degenerative vasculopathy (intimal fibromuscular hyperplasia and medial hypertrophy/hyperplasia) involving pulmonary arteries was also observed. The polymerase chain reaction amplification and sequencing confirmed the identification of the parasite as Dirofilaria immitis. A diagnosis of pulmonary artery dissection with haemothorax and concomitant heartworm disease was formulated. Degenerative processes of the tunica media have been reported to cause pulmonary artery dissection in both humans and animals. Pulmonary artery remodelling induced by heartworms may be considered the underlying cause in the first case of feline pulmonary artery dissection, herein described.

YAP1 up-regulation inhibits apoptosis of aortic dissection vascular smooth muscle cells.

OBJECTIVE: Elevated apoptosis of vascular smooth muscle cell (VSMC) is correlated with the occurrence of aortic dissection (AD). Yes-associated protein 1 (YAP1) is the major effector in Hippo-YAP signal pathway, which facilitates cell proliferation and suppressing apoptosis. Several studies have been performed regarding the relationship between YAP1 and AD pathogenesis. This study established the AD rat model to investigate possible roles of YAP1 in regulating VSMC apoptosis and AD pathogenesis. MATERIALS AND METHODS: Cell apoptosis and YAP1 expression were compared between AD vascular tissues and normal rats. In vitro studies with rat thoracic VSMCs were divided into control, cyclic stretch, cyclic stretch + pIRES2-blank and cyclic stretch + pIRES2-YAP1 groups. Cell apoptosis rate, YAP1 and survivin expressions were measured. AD rats were divided into model, Ad-NC injection, and Ad-YAP1 injection group for the detection of AD formation rate, expressions of YPA1 and survivin, and VSMCs apoptosis. RESULTS: Compared to control group, vascular cell apoptosis was increased, and YAP1 expression was reduced in AD rats. Cyclic stretch significantly induced VSMCs apoptosis. The over-expression of YAP1 up-regulated survivin and impeded the cell apoptosis induced by cyclic stretch. The treatment with Ad-YAP1 up-regulated the levels of YAP1 and survivin in AD model rat vascular tissues, and decreased apoptosis and AD formation rate/AD diameter/length. CONCLUSIONS: YAP1 played a critical role in affecting VSMC apoptosis and AD pathogenesis. Up-regulation of YAP1 decreased VSMC apoptosis and AD formation.

Pulmonary artery dissection following balloon valvuloplasty in a dog with pulmonic stenosis.

A 3-month-old, 9.9 kg, male pit bull cross was referred for evaluation of collapse. A left basilar systolic heart murmur graded V/VI and a grade IV/VI right basilar systolic heart murmur were ausculted. Echocardiography showed severe pulmonic stenosis characterized by annular hypoplasia, leaflet thickening, and leaflet fusion. After 1 month of atenolol therapy, a pulmonic valve balloon valvuloplasty procedure was performed, and the intra-operative right ventricular pressure was reduced by 43%. Echocardiography, performed the following day, showed apparent rupture of a pulmonary valve leaflet and a membranous structure within the pulmonary artery consistent with a dissecting membrane. Short-term follow-up has shown no apparent progression of the pulmonary artery dissection and the patient remains free of clinical signs.

Historical Incidence of Spontaneous Lesions in Kidneys from Naïve Swine Utilized In Interventional Renal Denervation Studies.

The use of preclinical animal models is integral to the safety assessment, pathogenesis research, and testing of diagnostic technologies and therapeutic interventions. With inherent similarity to human anatomy and physiology, various porcine models have been the preferred preclinical model in some research areas such as medical devices, wound healing, and skin therapies. The porcine model has been the cornerstone for interventional cardiology for the evaluation and development of this catheter-based renal denervation (RDN) therapy. The porcine model provides similar vascular access and renal neurovascular anatomy to humans. In these preclinical studies, the downstream kidneys from treated arteries are assessed for possible histopathological changes in the vessel dependent territories. In assessing renal safety following RDN, it becomes critical to distinguish treatment-related changes from pre-existing background pathologies. The incidence of background pathological changes in porcine kidneys has not been previously established in normal clinically healthy. Samples from the cranial, middle, and caudal portion of 331 naïve kidneys from 181 swine were processed histologically to slides and evaluated microscopically. The most commonly encountered spontaneous changes were chronic pyelonephritis found in nearly half of the evaluated naïve kidneys (∼40 %; score 1 = 91 %, score 2 = 8.4 %, score 3 = 0.76 %) followed by chronic interstitial inflammation in 9.7 % of the kidneys (score 1 = 90.6 %, score 2 = 9.4 %). Interestingly, there were a few rare spontaneous vascular changes that could potentially affect data interpretation in interventional and toxicology studies: arteritis and arteriolar dissection. The presence of pelvic cysts was a common occurrence (6.3 %) in the kidney. The domestic swine is a widely used preclinical species in interventional research, namely in the emerging field of transcatheter renal denervation. This retrospective study presents the historical incidence of spontaneous lesions recorded in the kidneys from naive pigs enrolled in renal denervation studies. There were commonly encountered changes of little pathological consequence such as pyelonephritis or pelvic cysts and rare vascular changes such as arteritis and arteriolar dissection that were of greater potential impact on study data interpretation. These results offer a benchmark by which to gage the potential effect of a procedure or treatment on renal histopathology in swine and assist in data interpretation.

A triple bifurcation aneurysm model for evaluating complex endovascular therapies in dogs.

OBJECT: Animal aneurysm models are required for the study of the hemodynamics and pathophysiology of intracranial aneurysms in humans and so that experimental treatments can be tested prior to clinical trials. The authors developed a canine model that consistently produces up to three bifurcation aneurysms similar in morphological features and hemodynamics to human intracranial aneurysms. METHODS: In 10 mongrel dogs, a harvested segment of the external jugular vein was anastamosed to an external carotid artery (CA)-lingual artery bifurcation arteriotomy site to create a lateral bifurcation aneurysm. The surgery was repeated on the contralateral side in each animal to form a second lateral bifurcation aneurysm and, in five dogs, a CA-CA crossover anastomosis was also performed to create a terminal bifurcation aneurysm. Nineteen of 20 lateral bifurcation aneurysms were confirmed in 10 dogs by diagnostic angiography 7 to 14 days after surgery. Aneurysm fundus-to-neck ratios ranged from 1 to 2, depending on the size of the arteriotomy. The terminal bifurcation aneurysms were confirmed in all five dogs by diagnostic angiography 7 to 14 days after the procedure. The authors later tested endovascular techniques for embolizing the aneurysms. CONCLUSIONS: Three bifurcation aneurysms of sufficient size for endovascular access can be created in a reproducible fashion in the same animal. This model is useful for studying complex endovascular procedures in aneurysms that mimic the human condition and for testing new devices and techniques.

Spontaneous aortic dissecting hematoma in two dogs.

This report describes 2 cases of spontaneous aortic dissecting hematoma in young Border Collie and Border Collie crossbred dogs. Histology was performed in one of the cases involving an unusual splitting of the elastin present within the wall of the aorta, consistent with elastin dysplasia as described in Marfan syndrome in humans. The first case involved a young purebred Border Collie that died suddenly and the second case involved a Border Collie crossbred dog that died after a 1-month history of seizures. Gross lesions included pericardial tamponade with dissection of the ascending aorta in the former case and thoracic cavity hemorrhage, mediastinal hematoma, and aortic dissection in the latter. Histologic lesions in the case of the Border Collie crossbred dog included a dissecting hematoma of the ascending aorta with elastin dysplasia and right axillary arterial intimal proliferation.

Aortic tear and dissection related to connective tissues abnormalities resembling Marfan syndrome in a Great Dane.

Aortic tears and acute aortic dissection are rarely reported in dogs. This report describes a case of aortic dissection and probable sinus of Valsalva rupture in a young Great Dane with associated histopathologic findings suggestive of a connective tissue abnormality.

Pulmonary artery dissection in eight dogs with patent ductus arteriosus.

OBJECTIVES: To describe a series of dogs with pulmonary artery dissection and patent ductus arteriosus (PDA). ANIMALS: Eight dogs. METHODS: Retrospective case series. RESULTS: Pulmonary artery dissection was diagnosed in 8 dogs, 3 were Weimaraners. Four dogs presented in left-sided congestive heart failure, 4 presented for murmur evaluation and without clinical signs, and 1 presented in right-sided congestive heart failure. In 7 dogs the dissection was first documented concurrent with a diagnosis of uncorrected PDA. In the other dog, with pulmonary valve stenosis and PDA, the dissection was observed on autopsy examination 17 months after balloon pulmonary valvuloplasty and ductal closure. Median age at presentation for the 7 dogs with antemortem diagnosis of pulmonary artery dissection was 3.5 years (range, 1.5-4 years). Three dogs had the PDA surgically ligated, 2 dogs did not undergo PDA closure, 1 dog failed transcatheter occlusion of the PDA with subsequent surgical ligation, 1 dog underwent successful transcatheter device occlusion of the PDA, and 1 dog had the PDA closed by transcatheter coil delivery 17 months prior to the diagnosis of pulmonary artery dissection. The 2 dogs that did not have the PDA closed died 1 and 3 years after diagnosis due to heart failure. CONCLUSIONS: Pulmonary artery dissection is a potential complication of PDA in dogs, the Weimaraner breed may be at increased risk, presentation is often in mature dogs, and closure of the PDA can be performed and appears to improve outcome.

Proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich.

The gross and histopathologic lesions observed in a case of spontaneous proximal aortic dissection (dissecting aortic aneurysm) in a mature ostrich are reported. At necropsy, a dissecting intramural hematoma was seen in the proximal aorta, extended about 12 cm distally from the aortic valves. Histopathologic changes in aortic dissection included fragmentation and disruption of elastic laminae, presence of cystic extracellular spaces, and pooling of ground substance in the tunica media. Hepatic copper levels were measured, and the low concentration found suggested that a copper deficiency together with other risk factors such as the elevation of blood pressure may have been implicated in the development of the aortic dissection seen in this ostrich.

A dissecting aneurysm in the bulbus arteriosus of a brook stickleback, Culaea inconstans.

In the bulbus arteriosus of an adult, male brook stickleback, C. inconstans, one of 100 caught in July 1982 from Lake 200, near Erickson, Manitoba, Canada, there was a dissecting aneurysm similar to those in the human aorta. The vessel also showed the classic signs of Erdheim's "idiopathic cystic medionecrosis", but its lumen was dilated and the lesion could thus also be regarded as a fusiform aneurysm. In the proximal half of the bulbus the endothelial lining was torn transversely and blood had extended into the middle layer of the wall to create 2 concentric and longitudinal channels which re-entered the lumen distally at approximately the mid-point of the bulbus. Except near the bulbar-aortic junction, the amount of elastica and (probably) smooth muscle was drastically reduced, the wall was infiltrated with amorphous deposits of mucoid substances, there were focal, cyst-like areas, and the normally tall and intensely PAS-positive, endothelial cells were flattened and poorly staining. There was no evidence of cystic medionecrosis in the bulbus arteriosus of other fish without dissecting aneurysms. This is thought to be the first report of a dissecting aneurysm in any lower vertebrate. Evidently, such an aneurysm can occur in a vessel without vasa vasorum, and in a very small animal (48 mm long), where the wall tension in its blood vessels must be extremely low compared with that in the human aorta.

Dissecting aortic aneurysm in a horse.

A case of dissecting aortic aneurysm in a 4-year-old male thoroughbred horse is reported. The horse had a history of inflammation in the right thigh and a fever 2 weeks before sudden death. At necropsy, aortic aneurysms were observed from the aortic valve to the aortic arch, spreading over a distance of 40 cm. An irregular rupture of the intima of the ascending aorta was located in the cardiac side of a ramification to the tunica branchiocephalicus communis. An intramural haematoma, apparent on the cut surface and in the pericardium, had caused cardiac tamponade and sudden death.