Echocardiographic assessment of the left ventricular outflow tract in the Boxer

BACKGROUND: Soft, variable ejection murmurs are common in Boxers and are associated with increased left ventricular outflow tract (LVOT) ejection velocities. Whether these murmurs are physiologic or indicate mild aortic stenosis is controversial. Ejection velocity is impacted by LVOT area and ventricular stroke volume (SV), suggesting that these variables are pertinent to murmur development. HYPOTHESIS: Boxers with ejection murmurs have a smaller LVOT and equivalent SV indices, compared with values in dogs without murmurs. ANIMALS: Three age- and weight-matched groups of dogs--15 Boxers with soft ejection murmurs (group I); 15 Boxers without murmurs (group II); and 15 nonBoxer dogs without murmurs (group III)--were studied. METHODS: All dogs underwent 2-dimensional and Doppler echocardiographic examinations. The LVOT size at multiple levels; LVOT ejection velocity, stroke distance, and SV index; and right ventricular SV index were determined and compared by analysis of variance. RESULTS: Indexed LVOT areas in Boxer groups were not different, but were significantly smaller than those of non-Boxer dogs. Ejection velocities and stroke distances were significantly different across all groups, with group I having the highest and group III having the lowest values. Doppler SV indices (ml/m2) for group-I versus group-II Boxers were 70 +/- 16(SD) versus 62 +/- 12 for the LVOT (P = .27) and 58 +/- 12 versus 48 +/- 9 for the right ventricle (P = .14). CONCLUSIONS AND CLINICAL IMPORTANCE: These data suggest that a relatively smaller LVOT in Boxers predisposes them to increased ejection velocity and development of murmurs. The contribution of SV to the genesis of these often labile murmurs requires additional study.     

EFFECTS OF IMAGE PLANE,PATIENT POSITIONING,AND FORAMINAL ZONE ON MAGNETIC RESONANCE IMAGING MEASUREMENTS OF CANINE LUMBOSACRAL INTERVERTEBRAL FORAMINA

Degenerative lumbosacral stenosis has been suspected to have a dynamic component, especially regarding encroachment of the L7 nerve roots exiting the lumbosacral foramina. Angled cross‐sectional imaging of the neuroforamina has been found improve the accuracy of the diagnosis of stenosis in humans. In this anatomic study, foraminal apertures were evaluated by MRI at the entry, middle, and exit zones of the nerve roots in 30 dogs that were clinically affected by lumbosacral disease. Standard vs. oblique planar orientation and neutral vs. hyperextended positioning of the lumbosacral area were compared by measuring the median values for entry, middle, and exit zones. The neuroforaminal area acquired using oblique plane acquisition was significantly smaller than standard parasagittal measurements. Furthermore, standard parasagittal neuroforaminal dimensions in the hyperextended position were significantly smaller than standard parasagittal measurements in the neutral position. This statistical difference was even more pronounced for neuroforaminal dimension evaluated in the oblique plane and hyperextended position. Positioning of the dog during imaging has a significant effect on neuroforaminal dimension, corroborating the notion that spinal position may influence neural claudication in clinically affected patients. Reductions in neuroforaminal dimension are more evident on oblique planar image acquisition, suggesting that this approach may be more useful than parasagittal imaging as a tool for identifying subtle changes in L7 neuroforaminal dimensions in cases of canine lumbosacral stenosis.     

PERIPHERAL PULMONARY ARTERY STENOSIS IN A FOUR-MONTH-OLD WEST HIGHLAND WHITE TERRIER

A 4-month-old West Highland White Terrier was evaluated for dyspnea. Severe cardiac silhouette enlargement was present radiographically. Severe right ventricular hypertrophy and dilation with a dilated pulmonary trunk and a stenosis of the right pulmonary artery were diagnosed via echocardiography. Additional areas of peripheral pulmonary artery stenosis were diagnosed with nonselective computed tomography (CT) angiography and selective fluoroscopic angiography. Balloon dilation therapy was unsuccessful and the imaging findings were confirmed at necropsy.     

Equine intervertebral disk disease: A case report

Intervertebral disk disease is common in humans and dogs but is rarely reported in horses. In this case report, we describe an 11-year-old American Saddlebred gelding with a 2-month history of pain and progressive neurological abnormalities (ataxia, conscious proprioceptive deficits involving all four limbs, toe dragging, and restricted neck flexion) while being worked as a Saddleseat show horse. Radiographs of the cervical spine showed a loss of the intervertebral disk space at C₆–C₇. At necropsy, nearly complete loss of the intervertebral disk at C₆–C₇ was seen, with marked eburnation and subchondral sclerosis of the adjacent vertebral endplates that were confirmed by histopathology. Many of the marrow spaces of the affected vertebral bodies were filled with cartilage and others contained variable amounts of fibrous connective tissue (myelofibrosis). To our knowledge, these pathological lesions are rarely reported in the literature and appear to represent a chronic, end-stage phase of cervical vertebral stenosis.     

The 1st balloon valvuloplasty: an historical note

Balloon valvuloplasty (BV) is currently the treatment of choice for pulmonic stenosis in humans and dogs. Before permission was obtained to attempt the 1st BV in a child in 1982, the safety and efficacy of the procedure were tested in 1980 in an English Bulldog with spontaneous pulmonic stenosis. A fatal outcome would have caused indefinite postponement of BV in human patients, a procedure that currently benefits over 25,000 patients a year worldwide. This article describes the initial test procedure and its fortunate outcome in spite of unrecognized coronary anomalies in the bulldog. A small balloon was used in the test procedure, and fatal disruption of the anomalous left coronary artery (CA) did not occur as it has in several bulldogs since that time.     

Stenosis hemodynamics: from physical principles to clinical indices

Clinical evaluation of patients with aortic stenosis entails hemodynamic determinations and interpretations that depend on complex blood flow patterns. Although pressure gradient and Doppler velocity are intrinsically adjusted for a wide range of species and body size, they are highly flow-dependent indices that can vary among patients with physically identical stenosis areas and within individuals between determinations. Other indices, such as the Gorlin area, are adjusted for flow. All stenosis indices derived from hemodynamic measurements, however, must exhibit some degree of flow dependence because of fundamental aspects of fluid dynamics that affect the blood velocity profile. The Gorlin effective orifice area is an index that sacrifices adjustment for body size. This hinders comparisons over a range of patient species, breed, and size because it may be problematic to determine what effective orifice area is appropriate for a given individual. One potential solution is to compare the effective area of an individual's normal tract, if one exists, to the tract in question as a ratio, the effective orifice area ratio (EOAR). The EOAR can be estimated from the ratio of flow velocity integrals (FVIs) of the 2 outflow tracts. Clinical data and experience are lacking, but theoretical advantages of the index include intrinsic adjustment for both body size and flow rate. Aortic stenosis is a complex, multifactorial disease, and selection of an optimal hemodynamic severity index may not result in adequate prognostic criteria for segregation of patient risk and treatment groups.     

Restenosis after balloon valvuloplasty in a dog with pulmonary stenosis

A two-month-old female Chihuahua was diagnosed as severe pulmonary valvular stenosis (PS). Although balloon valvuloplasty (BV) was successfully performed, restenosis was observed 19 months after the procedure. Euthanasia was chosen due to low output syndrome during the surgical repair attempted when the dog was 5 years old. Postmortem examination revealed markedly thickened pulmonary valve due to the increase of extracellular matrix which might be produced by increased α smooth muscle actin-positive myofibroblasts. The thickening of the valve was associated with restriction of the valve’s motion, resulting in restenosis in the present case. This is the first case report documented histopathological and immunohistochemical findings of the restenotic pulmonary valve in dogs with PS after BV.     

移植肾动脉狭窄的支架治疗效果与安全性探讨

目的探讨移植肾动脉狭窄的支架治疗效果与安全性.方法1例肾移植术后的女性患者,2 a前采用移植肾动脉与髂内动脉远端行端-端吻合术,移植肾脏固定在右髂窝内.术后2 a发生移植肾动脉狭窄80%,狭窄性病变长度15 mm,接受了支架治疗.从左股动脉入路,应用Judkin 6F右冠指引导管,植入冠脉金属裸支架4.0 mm×18 mm的R-stent,18 atm×20 s释放.结果支架扩张和贴壁良好,狭窄病变解除,无残余狭窄,血流TIMIⅢ级,术后患者血压平稳.结论支架术治疗移植肾动脉狭窄效果显著,安全.     

Clinical, morphologic, and morphometric features of cranial thoracic spinal stenosis in large and giant breed dogs

The clinical, morphologic, and morphometric features of cranial thoracic spinal stenosis were investigated in large and giant breed dogs. Seventy-nine magnetic resonance imaging studies of the cranial thoracic spine were assessed. Twenty-six were retrieved retrospectively and 53 were acquired prospectively using the same inclusion criteria. Images were evaluated using a modified compression scale as: no osseous stenosis (grade 0), osseous stenosis without spinal cord compression (grade 1), and osseous stenosis with spinal cord compression (grade 2). Morphometric analysis was performed and compared to the subjective grading system. Grades 1 and 2 cranial thoracic spinal stenosis were identified on 24 imaging studies in 23 dogs. Sixteen of 23 dogs had a conformation typified by Molosser breeds and 21/23 were male. The most common sites of stenosis were T2-3 and T3-4. The articular process joints were enlarged with abnormal oblique orientation. Stenosis was dorsolateral, lateralized, or dorsoventral. Concurrent osseous cervical spondylomyelopathy was recognized in six dogs and other neurologic disease in five dogs. Cranial thoracic spinal stenosis was the only finding in 12 dogs. In 9 of these 12 dogs (all grade 2) neurolocalization was to the T3-L3 spinal segment. The median age of these dogs was 9.5 months. In the remaining three dogs neurologic signs were not present. Stenosis ratios were of limited benefit in detecting stenotic sites. Grade 2 cranial thoracic spinal stenosis causing direct spinal cord compression may lead to neurologic signs, however milder stenosis (grade 1) is likely to be subclinical or incidental.