Hansen type I disk disease at T1-2 in a dachshund.

A 7-year-old Dachshund was presented with chronic left thoracic limb lameness and acute neurological deficits to the hind limbs following trauma. A lesion was suspected between C7 and T2 on the basis of neurological examinations. Radiography and myelography identified a calcified intervertebral disk at C7-T1 and an extradural unilateral compressive lesion at T1-2. Computed tomography scans of the cranial thoracic spine revealed extrusion of disk material from the T1-2 intervertebral space resulting in marked spinal cord compression. Intervertebral disk disease is rarely reported at this location. The neurological condition deteriorated after a second myelogram, which was done to examine the thoracolumbar spine. A modified dorsal decompression of T1-2 was performed. The dog was euthanased due to further neurological deterioration 8 days after surgery.

Bilateral internal carotid artery occlusion: natural history and surgical alternatives.

PURPOSE AND BACKGROUND: Bilateral internal carotid artery occlusion is an extremely rare entity, therefore, studies of the natural history of this disease are lacking in the English literature. The purpose of this study is to analyze the natural history and surgical alternatives for patients with bilateral internal carotid artery occlusion. PATIENT POPULATION AND METHODS: Twenty-one patients with bilateral internal carotid artery occlusion were encountered with a mean age of 61 years (range of 48-73 years). Their clinical presentations included eight with hemispheric transient ischemic attacks, three with amaurosis fugax, five with strokes and five with non-hemispheric transient ischemic attack. Diagnosis was confirmed using carotid duplex ultrasound and angiography. The majority of patients had more than one risk factor for atherosclerosis: smoking in 100%, hyperlipidemia in 14/21 (67%), hypertension in 17/21 (81%), coronary artery disease in 15/21 (71%) and diabetes mellitus in 7/21 (33%). In addition to the usual medical treatment, 13 patients underwent surgical intervention: eight had an external carotid endarterectomy, four had a carotid-subclavian bypass (to increase external carotid or vertebral flow for tight stenosis or occlusion of the common carotid or subclavian artery) and one patient had an ascending aorta to innominate artery bypass. At a mean follow-up of 6 years (range 1-11 years), the overall mortality rates were 11/21 (52%), in the surgical group it was 5/13 (38%) and 6/8 (75%) in the medical group. The causes of death included seven myocardial infarctions (four in the surgical group and three in the medical group) and four strokes (one in the surgical group and three in the medical group). In the surgical group, 2/13 (15%) had late neurological deficits (one hemispheric transient ischemic attack and one stroke), in contrast to 6/8 (75%, three strokes and three hemispheric transient ischemic attacks) in the medical group. CONCLUSIONS: Bilateral internal carotid artery occlusions have grave prognoses and should be considered a marker for severe systemic disease. Various cerebrovascular reconstructive procedures, if feasible, may be beneficial for some of these patients.

Right ventricular preload recruitable stroke work, end-systolic pressure-volume, and dP/dtmax-end-diastolic volume relations compared as indexes of right ventricular contractile performance in conscious dogs.

Three indexes developed originally to assess left ventricular contractile performance were applied instead to the right ventricle (RV) in 11 conscious dogs: the relation between stroke work and end-diastolic volume (EDV), termed the preload recruitable stroke work (PRSW) relation; the end-systolic pressure-volume (ESPV) relation; and the maximum dP/dt (dP/dtmax)-EDV relation. The reproducibility, inotropic sensitivity, chronotropic sensitivity, and afterload sensitivity of these RV relations were compared. RV volume was determined with an ellipsoidal shell subtraction model from orthogonal dimensions measured by sonomicrometry. RV transmural pressure was measured with micromanometers. After autonomic blockade, preload was varied by repeated, transient vena caval occlusions before and during partial occlusion of the main pulmonary artery, after release of the pulmonary arterial occlusion, after calcium infusion, and over a range of heart rates induced by atrial pacing. The slope and volume-axis intercept of the PRSW relation were more reproducible (SD/mean, 7.8 +/- 3.3% and 6.2 +/- 4.1%, respectively) than the slope and volume-axis intercept of the ESPV relation (10.1 +/- 6.7% and 23.0 +/- 31.3%, both p less than 0.05) or the slope and volume-axis intercept of the dP/dtmax-EDV relation (43.4 +/- 70.4% and 153.8 +/- 184.6%, both p less than 0.05). The slope of the PRSW relation increased 32 +/- 17% (p less than 0.05) after calcium infusion, but the volume-axis intercept did not change significantly. In contrast, the slopes of the ESPV and dP/dtmax-EDV relations did not change significantly after calcium infusion, but the volume-axis intercepts decreased significantly (both p less than 0.05). Despite a 71 +/- 26% increase in mean RV ejection pressure during partial occlusion of the main pulmonary artery, the slopes and volume-axis intercepts of both the PRSW and dP/dtmax-EDV relations did not change significantly, but the slope of the ESPV relation increased 45 +/- 22% (p less than 0.05) without significant change in the volume-axis intercept. None of the relations demonstrated significant chronotropic sensitivity. The PRSW relation is the preferred index of RV contractile performance because 1) it is the most reproducible, 2) its slope alone sensitively detects changes in contractile state, and 3) unlike the ESPV relation, it is relatively insensitive to afterload.