Atrial septal pouch in cats: first report on interatrial septum anatomical variations.

OBJECTIVES: The atrial septal pouch was first recognised in humans in 2006 and, since 2010, has been described in more detail. The first reports on the left-sided atrial septal pouch linked its occurrence with a higher risk of thromboembolic stroke resulting from left atrial thrombus formation. However, subsequent studies have challenged this theory; therefore, the consequences of septal pouch occurrence remain disputed. Currently, in veterinary species, septal pouch occurrence and morphology have been described in sheep and pigs, showing species-related differences. No studies have been conducted on cats. As cats show a species-related risk of aortic thromboembolic disease resulting from left atrial thrombus formation, we aimed to describe the interatrial septum anatomical variations as the first step in the investigation of the relationship between the septal pouch presence and left atrial thrombus formation. METHODS: The study was conducted on hearts collected post mortem from 80 cats. After formalin fixation and dissection, a detailed anatomical description of the interatrial septum for all cases was followed by a histopathological analysis of the heart in 25 cases. After dissection, the specimens were embedded in paraffin blocks and stained with haematoxylin and eosin, Masson-Goldner trichrome, Picrosirius Red and Movat pentachrome in a routine manner and evaluated via light microscopy. RESULTS: Our study showed a very high prevalence (95%) of the left-sided septal pouch in cats with a lower incidence (29%) of the right-sided septal pouch. We noted a high morphological variety of the left-sided septal pouch and described anatomical variants not previously reported in the literature. CONCLUSIONS AND RELEVANCE: The septal pouch is a common anatomical variation of the interatrial septum in cats. Although, based on the current study, we cannot draw further conclusions on the relationship between the left-sided septal pouch and thromboembolic events in cats, the high prevalence of this anatomical entity points to a need of further studies on the topic.

Feline aortic thromboembolism with and without congestive heart failure did not exhibit hypercoagulability using a novel viscoelastic coagulation monitor.

OBJECTIVE: To demonstrate hypercoagulability with a benchtop viscoelastic monitor in cats with congestive heart failure (CHF) and/or aortic thromboembolism (ATE) compared to controls. METHODS: 97 cats were enrolled throughout this prospective observational cohort study from September 2022 through October 2023. Cats were grouped by diagnosis of CHF, ATE, ATE plus CHF, or controls. Enrollment required diagnosis of heart disease and no previous antithrombotic therapy. The results of viscoelastic testing with the benchtop viscoelastic coagulation monitor (VCM Vet [VCM]; Entegrion) were compared between groups using factorial analysis of variance. RESULTS: Cats with heart disease had significantly higher clot times when compared to controls (control: mean, 285.3 [SD, 172.6]; CHF: mean, 391.7 [SD, 106.8]; ATE: mean, 415.9 [SD, 109.2]; and ATE plus CHF: mean, 368.6 [SD, 232.6]). Heart disease cats were noted to have significantly lower 45-minute lysis index values (control: median, 100 [range, 93 to 100]; CHF: median, 99 [range, 89 to 100]; ATE: median, 98 [range, 88 to 100]; and ATE plus CHF: range, 98 [91 to 100]). Age was a covariate to this variable, and when applied to analysis, statistical significance was lost. No significant difference in any other variables were noted. CLINICAL RELEVANCE: The hypercoagulability of ATE and CHF cats was not detected by the VCM. Further research with other coagulation monitors is required in this population.

Ultrasonographic findings of feline aortic thromboembolism.

OBJECTIVES: The aim of the study was to describe the ultrasonographic characteristics of feline aortic thromboembolism (ATE) and determine potential associations between ultrasonographic findings and prognosis. METHODS: Data were retrospectively collected from the medical records (2013-2021) of cats that were diagnosed ultrasonographically with ATE based on the presence of a thromboembolus (TE) in the distal aorta beginning after the departure of the renal arteries. RESULTS: Twenty-nine cats were included in this study. The most frequent location for an ATE was at the aortic trifurcation. The median length of TEs was 9 mm (range 3.5-42.9). TEs appeared homogeneous and isoechoic to surrounding tissues in all cases. No correlation was found between the appearance of the TE and the duration of clinical signs. The obstruction of blood flow in the distal aorta at the aortic trifurcation was complete in 66% of cases and incomplete in 34% of cases. The survival rate was significantly lower when the obstruction was complete (11%, 95% confidence interval [CI] 2-34) compared with incomplete (70%, 95% CI 35-92). The arterial wall characteristics were as follows: smooth and thin (62%), and hyperechoic (38%). CONCLUSIONS AND RELEVANCE: Increased vascular obstruction of TEs was associated with a lower survival rate.

Extensive Aortic Thromboembolism in a Patient With Erdheim-Chester Disease: A Case Report.

Background: Erdheim-Chester disease (ECD) is a rare disease that affects multiple systems and is characterized by non-Langerhans cell histiocytosis. Classic clinical signs include long bone infiltration, central nervous system involvement, diabetes insipidus, and sheathing of the entire aorta. However, thrombosis is not recognized as a typical cardiac manifestation of ECD. Here, we report the case of an ECD patient with extensive arterial thrombus formation and embolism in several sections of the aorta. Case: A 36-year-old woman was admitted due to recurrent fever and left finger cyanosis for 20 days. Laboratory tests revealed that her C-reactive protein and interleukin-6 levels were significantly elevated. Thoracic computed tomographic angiography (CTA) revealed thrombosis from the aortic arch to the left subclavian artery accompanied by severe stenosis of the left subclavian artery. Abdominal CTA revealed splenic infarction due to splenic artery embolism and thrombus formation in multiple abdominal arteries. She underwent emergent arterial thrombectomy. During hospitalization, she complained of polyuria. The desmopressin test and pituitary magnetic resonance imaging findings suggested diabetes insipidus. Furthermore, positron emission tomography-computed tomography and bone emission computed tomography showed long bone impairment, and pathological examination of the bone samples confirmed ECD. Steroids and tocilizumab were selected as the initial therapies; however, thrombosis continued to develop. After replacement of tocilizumab with interferon-α, her condition became stable. Conclusion: Although extremely rare, fatal thrombosis may be a significant cardiovascular manifestation of ECD.

Immunohistological Evaluation of Von Willebrand Factor in the Left Atrial Endocardium and Atrial Thrombi from Cats with Cardiomyopathy.

Aortic thromboembolism (ATE) occurs in cats with cardiomyopathy and often results in euthanasia due to poor prognosis. However, the underlying predisposing mechanisms leading to left atrial (LA) thrombus formation are not fully characterised. von Willebrand Factor (vWF) is a marker of endothelium and shows increased expression following endothelial injury. In people with poor LA function and LA remodelling, vWF has been implicated in the development of LA thrombosis. In this study we have shown (1) the expression of endocardial vWF protein detected using immunohistofluorescence was elevated in cats with cardiomyopathy, LA enlargement (LAE) and clinical signs compared to cats with subclinical cardiomyopathy and control cats; (2) vWF was present at the periphery of microthrombi and macrothrombi within the LA where they come into contact with the LA endocardium and (3) vWF was integral to the structure of the macrothrombi retrieved from the atria. These results provide evidence for damage of the endocardial endothelium in the remodelled LA and support a role for endocardial vWF as a pro-thrombotic substrate potentially contributing to the development of ATE in cats with underlying cardiomyopathy and LAE. Results from this naturally occurring feline model may inform research into human thrombogenesis.

Focused Cardiac Ultrasonography in Cats.

Heart disease is a common cause of morbidity and mortality in cats. Focused cardiac ultrasonography (FCU) is a useful diagnostic tool for identifying heart disease in symptomatic and asymptomatic cats when performed by trained veterinarians. When used in conjunction with other diagnostics such as physical examination, blood biomarkers, electrocardiography, Global FAST, and other point-of-care ultrasonographic examinations, FCU may improve clinical decision making and help clinicians prioritize which cats would benefit from referral for complete echocardiography and cardiac consultation. This article reviews the definition, advantages, clinical indications, limitations, training recommendations, and a protocol for FCU in cats.

Feline aortic thromboembolism: Presentation, diagnosis, and treatment outcomes of 15 cats.

Background: Feline aortic thromboembolism (FATE) is a fatal disease where a blood clot gets lodged into the aortic trifurcation. Methods: Fifteen cats with a sudden onset of hind limb paresis/paralysis, vocalization, and pain were admitted to the surgery clinic. A full case history was obtained and clinical, orthopedic, neurologic, radiographic, electrocardiographic, and echocardiographic examinations were performed for each cat. The treatment protocol included daily administration of multiple anticoagulant drugs with different mode of actions and meloxicam for 7 successive days. Prophylactic anticoagulant therapy (clopidogrel and acetylsalicylic acid) was continued for 6 months. All data were statistically analyzed and the correlation between time of admission and treatment outcome was tested using Pearson's correlation coefficient. Results: The case history and clinical, orthopedic, and neurologic examinations revealed a sudden onset of hind limb paralysis (n = 12) or paresis (n = 3) associated with vocalization and pain, absence of trauma, cold and pale paws of hind limbs (n = 13, 86.7%) or cyanosed hind paws (n = 2, 13.3%), absence of femoral pulsation, shallow and rapid open-mouth respiration (61 ± 8 breaths/minutes), hypothermia (37.9°C ± 0.6°C) and tachycardia (155 ± 12 beats/minutes), with a muffled heart sound in four cats (26.7%). Radiography revealed no abnormalities in the hind limbs, pelvis, and spines, cardiomegaly in five cats (33.3%), mild pleural effusion and vascular pattern of the lung in six cats (40%), and Valentine's heart shape in four cats (26.7%). Electrocardiography (ECG) revealed an R-wave< 0.9 mV, prolongation of QRS interval in five cats (33.3%), and conduction disturbance in four cats (26.7%). Echocardiography was consistent with hypertrophic cardiomyopathy (HCM) in five cats (33.3%). A statistically significant (p= 0.023) strong negative correlation (r= -0.6) was reported between time of admission and subsequent early treatment and recovery from clinical signs. The treatment was successful in nine cats (60%), while four cats (26.7) were euthanized and two cats (13.3%) were subjected to hind limb amputation, at the owners' requests. Conclusion: Clinical signs, radiography, ECG, and echocardiography are valuable for diagnosis of FATE. The outcome of the multiple anticoagulants therapy depends mainly upon early diagnosis and treatment within the first 6 hours from the onset of clinical signs.

Vascular surgery of aortic thrombosis in a dog using Fogarty maneuver - technical feasibility.

Aortic thromboembolism is a rare and life-threatening disease in dogs. This report aims to describe the successful surgical treatment by use of a Fogarty Thrombectomy Catheter in an 8-year-old patient. The postsurgical intensive care therapy to prevent ischemia-reperfusion syndrome is specified, despite poor outcome in our case (owner elected euthanasia).