Vertebral artery dissection in Turner's syndrome: diagnosis by magnetic resonance imaging.

Aortic artery dissection is a rare but well-recognized complication of Turner's syndrome. Isolated carotid or vertebral artery dissection has not previously been reported. The authors report the clinical and magnetic resonance imaging findings in a 30-year-old woman with Turner's syndrome who developed a high cervical spinal cord infarction with a Brown-Sequard syndrome owing to bilateral vertebral artery dissection. The diagnosis and management of the case is reviewed.

Comparison of four echocardiographic techniques for measuring left ventricular ejection fraction.

Accurate quantitative measurement of left ventricular (LV) ejection fraction (EF) by 2-dimensional echocardiography is limited by subjective visual endocardial border detection. Both harmonic and precision contrast microbubbles provide better delineation of endocardial borders than fundamental imaging. The aim of this study was to correlate 2-dimensional echocardiographic quantification of LVEF measured by 4 currently available techniques with radionuclide angiography. A total of 50 patients who underwent radionuclide (EF) measurement (47 of 50 had technically difficult echocardiograms by fundamental imaging) underwent echocardiography by 4 methods: fundamental alone, fundamental with contrast, harmonic alone, and harmonic with contrast. Three echocardiologists measured the biplane 2-dimensional echocardiographic LVEF independently and were blinded to radionuclide angiography. The correlation of echocardiographic EF with radionuclide EF improved incrementally with each method. However, contrast with harmonic imaging provided the closest correlation (r = 0.95, 0.96, and 0.95 as assessed by the 3 independent analysts.

In vivo magnetic resonance evaluation of atherosclerotic plaques in the human thoracic aorta: a comparison with transesophageal echocardiography.

BACKGROUND: The structure and composition of aortic atherosclerotic plaques are associated with the risk of future cardiovascular events. Magnetic resonance (MR) imaging may allow accurate visualization and characterization of aortic plaques. METHODS AND RESULTS: We developed a noninvasive MR method, free of motion and blood flow artifacts, for submillimeter imaging of the thoracic aortic wall. MR imaging was performed on a clinical MR system in 10 patients with aortic plaques identified by transesophageal echocardiography (TEE). Plaque composition, extent, and size were assessed from T1-, proton density-, and T2- weighted images. Comparison of 25 matched MR and TEE cross-sectional aortic plaque images showed a strong correlation for plaque composition (chi(2) = 43.5, P<0.0001; 80% overall agreement; n = 25) and mean maximum plaque thickness (r = 0.88, n = 25; 4.56+/-0.21 mm by MR and 4.62+/-0.31 mm by TEE). Overall aortic plaque extent as assessed by TEE and MR was also statistically significant (chi(2) = 61.77, P<0.0001; 80% overall agreement; n = 30 regions). CONCLUSIONS: This study demonstrates that noninvasive MR evaluation of the aorta compares well with TEE imaging for the assessment of atherosclerotic plaque thickness, extent, and composition. This MR method may prove useful for the in vivo study of aortic atherosclerosis.

Spontaneous resolution of pulmonary venous thrombosis after lung transplantation.

Thrombus formation at the pulmonary venous anastomotic site after lung transplantation may have catastrophic consequences, including allograft failure and stroke. However, treatment with systemic anticoagulation may facilitate bleeding in the early postoperative period. In the present report, we describe the clinical and transesophageal echocardiographic findings of pulmonary venous thrombosis in two patients in the immediate postoperative period after lung transplantation. Treatment with systemic anticoagulation was not feasible because of extensive postoperative thoracic bleeding in each instance. A conservative approach was taken on the basis of the small size of each thrombus and lack of accelerated flow velocity at the site of the thrombus. Each thrombus resolved spontaneously without clinical sequelae. These two cases suggest that thrombus size and flow velocity at the anastomotic site may be used to guide the clinical management of pulmonary venous thrombosis after lung transplantation.

"Bow-tie" mitral valve repair: an adjuvant technique for ischemic mitral regurgitation.

BACKGROUND: Current techniques of mitral valve repair rely on decreasing valve area to increase leaflet apposition, but fail to address subvalvular dysfunction. A novel repair has been introduced with partial left ventriculectomy, which apposes the anterior leaflet to a corresponding point on the posterior leaflet creating a double-orifice valve, with reported adequate control of mitral regurgitation. METHODS: We started to use the "bow-tie" repair as an adjunct to posterior ring annuloplasty in cases in which mitral regurgitation was not adequately controlled by decreasing mitral valve area (n = 6), or when placement of an annuloplasty ring was impractical (n = 4). Mean follow-up was 336 days (range, 82 to 551 days) with no postoperative deaths. RESULTS: Mitral regurgitation decreased from 3.6+/-0.5 to 0.8+/-0.4 (p < 0.0001), with a concomitant increase in ejection fraction from 33%+/-13% to 45%+/-11% (p = 0.0156) before hospital discharge. Mitral valve area, measured by pressure half-time, decreased from a mean of 2.5+/-0.3 to 2.1+/-0.3 cm2, with a mean transvalvular gradient of 4.5+/-2.0 mm Hg. In patients whose mitral valve was repaired using the bow-tie alone, mitral regurgitation was reduced from 4+, to a trace to 1+. Postoperatively, mitral valve area increased from 1.9 to 2.5 cm2 during exercise, further supporting the concept that this technique preserves mitral valve annular function. CONCLUSIONS: These observations suggest that the bow-tie repair may offer advantages over conventional techniques of mitral valve repair and should be considered as an adjunct, especially in patients with impaired left ventricular function.

Transesophageal echocardiography-guided transvenous biopsy of a cardiac sarcoma.

Transvenous endomyocardial biopsy is a well established procedure to diagnose rejection after heart transplantation as well as to assess for other cardiomyopathic processes. However, it is rarely used to obtain samples of unidentified cardiac masses. We report a case of a primary cardiac sarcoma in which the histologic diagnosis was provided by transesophageal echocardiography-guided transvenous biopsy. This procedure is accurate and can avoid the potential risk of a diagnostic thoracotomy.

Cross-linking of cell surface ganglioside GM1 induces the selective apoptosis of mature CD8+ T lymphocytes.

Gangliosides are glycosphingolipids found ubiquitously on the surface of mammalian cells. They contain a ceramide tail that is inserted into the membrane and exposed carbohydrate and sialic acid moieties. The non-toxic B subunit oligomer (EtxB) of Escherichia coli heat-labile enterotoxin (Etx) is a potent immunogen in vivo and has profound modulatory effects on EtxB-primed lymphocytes in vitro, properties which are dependent on its ability to bind to GM1 ganglioside receptors. Here, it is shown that cross-linking GM1 by EtxB causes a differential effect on mature CD4(+) and CD8(+) T cells from lymph node cultures proliferating in response to an unrelated antigen, ovalbumin. Addition of EtxB to such cultures led to the complete depletion of CD8(+) T cells compared with enhanced activation of CD4(+) cells [as measured by expression of CD25 (IL-2Ralpha)]. By contrast, addition of a mutant EtxB, EtxB(G33D), which does not bind to GM1, failed to trigger CD8(+) T cell depletion. When EtxB was added to isolated non-immune CD8(+) lymphocytes rapid (12-18 h) alterations in nuclear morphology and the appearance of sub-G0/G1 levels of DNA were induced; properties which are characteristic of cells undergoing apoptosis. EtxB(G33D) failed to trigger apoptosis, indicating that the induction of the apoptotic signal was dependent on the binding of GM1. These findings provide an insight into the potent immunogenicity and immunomodulatory properties of E. coli enterotoxins as well as heralding a novel method for the selective induction of apoptosis in mature CD8(+) T lymphocytes.