Aortic dissection associated with an obstructive aortic chondrosarcoma in a dog

Insulation break of the ventricular lead in a dog with a pacemaker

A 10-year-old female spayed mixed breed dog that had a transvenous pacemaker implanted four years prior was presented for the evaluation of episodes of transient loss of consciousness without any history of trauma that were unresponsive to anticonvulsant therapies. Intermittent failure to capture coupled with low impedance and high capture threshold were noted upon interrogation of the pacemaker. Radiography and fluoroscopy demonstrated a possible break in the insulation of the lead. After the placement of another transvenous pacemaker, the dog had no additional syncopal episodes, and anticonvulsants were tapered off. The dog developed an implant infection from the newly placed pacemaker, which prompted the removal of the infected pacemaker and the implantation of an epicardial pacemaker. However, the epicardial lead dislodged seven days after placement, and the dog was euthanized. During necropsy, the first transvenous lead was removed, and the insulation break was visually confirmed. Although an insulation break is a rare delayed complication of pacemaker implantation, this report shows how the diagnosis, suspected by typical interrogation findings, can be aided by radiographic and fluoroscopic investigations.

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.

Primary leiomyosarcoma of the jugular vein in a dog

A four-year-old, male, Labrador retriever was referred for removal of a spindle cell sarcoma involving the right jugular vein. A post-contrast CT scan showed a seven-centimeter subcutaneous mass originated from the right external jugular vein, which was partially obstructed and showing contrast stasis, suggested a primary intravascular tumor of the jugular vein. The mass was resected, and histological evaluation was consistent with grade II intravenous spindle cell sarcoma of the jugular vein. Immunohistochemical positivity for vimentin, desmin, and αSMA antibody and negativity for S-100 protein confirmed venous leiomyosarcoma. The dog received five doses of intravenous doxorubicin, and there was no recurrence of the tumor 30 months post treatment. In dogs, primary intravascular sarcomas are rare and primary venous leiomyosarcoma has not been described. A venous tumor may be considered as a differential diagnosis in dogs with ventral neck swelling.

Vasa Vasorum Arteriopathy: Relationship With Systemic Arterial Hypertension and Other Vascular Lesions in Cats

The vasa vasorum is a delicate network of small arterioles that supplies nutrients to the adventitia and outer media of large arteries. In humans, dysfunction of the vasa vasorum contributes to the pathogenesis of aortic dissection and atherosclerosis. Twenty-four cats from 1 to 18 years of age were prospectively evaluated. Cases were divided into 3 cohorts—with systemic hypertension, without systemic hypertension, and uncertain. Histologic sections of the aorta and main pulmonary artery, as well as sections of kidney and lung, were blindly examined by 2 pathologists. The severity of vasa vasorum arteriopathy was compared to the presence of renal arteriosclerosis, aortic medial degeneration, subintimal fibroplasia of the main pulmonary artery, and blood pressure. We found that vasa vasorum arteriopathy correlated strongly with hypertensive status, degree of renal arteriosclerosis, and lesions in the great vessels. The positive predictive value of a severe vasa vasorum score for systemic hypertension was 84.6%. Lesions of vasa vasorum arteriopathy were predictive of renal arteriosclerosis with 100% sensitivity and 64.7% specificity. The positive predictive value of a severe vasa vasorum score for the presence of aortic lesions was 69.2% vs 91.6% for lesions in the main pulmonary artery. The vasa vasorum appears to be an important responder to systemic hypertension in cats, and arteriopathy of this vascular bed has significant implications for the integrity of the great vessels.

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.

Use of an Amplatz Canine Ductal Occluder (ACDO) device to close an acquired aortopulmonary fistula with a hybrid approach in a dog

A 2-year-old recently spayed female Rottweiler was referred as an emergency with cardiac tamponade and the presence of an anomalous retrograde flow in the pulmonary artery. Echocardiography and angiography demonstrated a left-to-right aortopulmonary fistula. Clinical history and data indicated a possible infectious aetiology. Antibiotics and heart failure medications were administered for 30 days before intervention. Initial attempt at insertion of an Amplatz occluder by means of a percutaneous catheterization technique was tried but a safe release of the device was judged to be not possible due to the angle and the fragile and irregular margins of the window. A decision was made to proceed with a hybrid technique combining thoracotomy and direct pulmonary artery catheterization. This hybrid approach was successful with resolution of congestive heart failure with only residual mild paraprosthetic leakage.

Aortic chondroid neoplasia in two Labrador Retriever dogs

In the same week, two Labrador Retriever dogs presented to The Ohio State University Veterinary Medical Center for cardiac evaluation. The presenting signs in both dogs included: weight loss, weakness, lethargy, and decreased femoral pulses. The first dog presented in cardiogenic shock and biventricular congestive heart failure, which initially responded to treatment; however, the dog was euthanized due to deteriorating clinical condition. In contrast, the second dog had a milder clinical course without signs of congestive heart failure, and remained stable over the 2-month period of clinical evaluation prior to euthanasia. Echocardiographic evaluation revealed a dilated cardiomyopathy phenotype in the first dog, while a space-occupying intraluminal mass originating at the aortic valve with preserved left ventricular systolic function was observed in the second dog. At autopsy, each dog had a large obstructive luminal mass affecting the ascending aorta and arch. Histopathology revealed that the mass in the first dog was consistent with a benign chondroma, while in the second dog the morphologic characteristics, mitotic activity, and infiltrative growth justified a diagnosis of chondrosarcoma. This report presents the contrasting clinical disease progression and findings in two dogs with aortic neoplasia, with a proposed pathogenesis of cardiac failure secondary to aortic neoplasia.

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.

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.