The flail mitral valve: Echocardiographic findings by precordial and transesophageal imaging and doppler color flow mapping

AbstractTo determine the echocardiographic and Doppler characteristics of mitral regurgitation associated with a flail mitral valve, precordial and transesophageal echocardiography with pulsed wave and Doppler color flow mapping was performed in 17 patients with a flail mitral valve leaflet due to ruptured chordae tendineae (Group I) and 22 patients with moderate or severe mitral regurgitation due to other causes (Group II). Echocardiograms were performed before or during cardiac surgery; cardiac catheterization was also performed in 28 patients (72%). Mitral valve disease was confirmed at cardiac surgery in all patients.By echocardiography, the presence of a flail mitral valve leaflet was defined by the presence of abnormal mitral leaflet ccaptation or ruptured chordae. Using these criteria, transesophageal imaging showed a trend toward greater sensitivity and specificity than precordial imaging in the diagnosis of flail mitral valve leaflet. By Doppler color flow mapping, a flail mitral valve leaflet was also characterized by an eccentric, peripheral, circular mitral regurgitant jet that closely adhered to the walls of the left atrium. The direction of flow of the eccentric jet in the left atrium distinguished a flail anterior from a flail posterior leaflet. By transesophageal echocardiography with Doppler color flow mapping, the ratio of mitral regurgitant jet arc length to radius of curvature was significantly higher in Group I than Group II patients (5.0 ± 2.3 versus 0.7 ± 0.6, p < 0.001); all of the Group I patients and none of the Group II patients had a ratio >2.5.Thus, transesophageal imaging with Doppler color flow mapping of mitral regurgitation is complementary to precordial echocardiography in the diagnosis and localization of flail mitral valve leaflet due to ruptured chordae tendineae

The echo-transponder electrode catheter: A new method for mapping the left ventricle

AbstractThe ability to locate catheter position in the left ventricle with respect to endocardial landmarks might enhance the accuracy of ventricular tachycardia mapping. An echotransponder system (Telectronics, Inc.) was compared with biplane fluoroscopy for left ventricular endocardial mapping. A 6F electrode catheter was modified with the addition of a piezoelectric crystal 5 mm from the tip. This crystal was connected to a transponder that received and transmitted ultrasound, resulting in a discrete artifact on the two-dimensional echocardiographic image corresponding to the position of the catheter tip.Catheters were introduced percutaneously into the left ventricle of nine anesthetized dogs. Two-dimensional echotransponder and biplane fluoroscopic images were recorded on videotape with the catheter at multiple endocardial sites. Catheter location was marked by delivering radiofrequency current to the distal electrode, creating a small endocardial lesion. Catheter location by echo-transponder and by fluoroscopy were compared with lesion location without knowledge of other data. Location by echo-transponder was 8.7 ± 5.1 mm from the center of the radiofrequency lesion versus 14 + 7.8 mm by fluoroscopy (n = 15, p = 0.023). Echo-transponder localization is more precise than is biplane fluoroscopy and may enhance the accuracy of left ventricular eledrophysiologic mapping

Acute Idiopathic Hemorrhagic Pericarditis with Cardiac Tamponade as the Initial Presentation of Acquired Immune Deficiency Syndrome

This paper presents a case of cardiac tamponade with idiopathic hemorrhagic pericarditis as the initial symptom of human immunodeficiency virus (HIV) infection. A 29-year-old male came to the emergency room with a sudden onset of dizziness. Upon arrival, he was hypotensive although not tachycardic, and his jugular venous pressure was not elevated. His chest X-rays revealed a mild cardiomegaly. Transthoracic echocardiography revealed a large amount of pericardial effusion with a diastolic collapse of the right ventricle, a dilated inferior vena cava with little change in respiration, and exaggerated respiratory variation of mitral inflow velocities, representing echocardiographic evidence of cardiac tamponade. After pericardiocentesis, his blood pressure improved to 110/70 mmHg without inotropics support. Serial 12-lead electrocardiograms during hospitalization revealed upwardly concave diffuse ST-segment elevation followed by a T-wave inversion suggestive of acute pericarditis. Pericardial fluid cytology and cultures for bacteria, mycobacteria, adenovirus, and fungus were all negative. HIV enzyme-linked immunosorbent assay (ELISA) was positive and confirmed by Western blot. The CD4 cell count was 168/mm3. Finally, the diagnosis of cardiac tamponade due to HIV-associated hemorrhagic pericarditis was made. It was concluded that HIV infection should be considered in the diagnosis of unexplained pericardial effusion or cardiac tamponade in Korea

Serum VEGF levels are related to the presence of pulmonary arterial hypertension in systemic sclerosis

<p>Abstract</p> <p>Background</p> <p>The association between systemic sclerosis and pulmonary arterial hypertension (PAH) is well recognized. Vascular endothelial growth factor (VEGF) has been reported to play an important role in pulmonary hypertension. The aim of the present study was to examine the relationship between systolic pulmonary artery pressure, clinical and functional manifestations of the disease and serum VEGF levels in systemic sclerosis.</p> <p>Methods</p> <p>Serum VEGF levels were measured in 40 patients with systemic sclerosis and 13 control subjects. All patients underwent clinical examination, pulmonary function tests and echocardiography.</p> <p>Results</p> <p>Serum VEGF levels were higher in systemic sclerosis patients with sPAP ≥ 35 mmHg than in those with sPAP < 35 mmHg (352 (266, 462 pg/ml)) vs (240 (201, 275 pg/ml)) (p < 0.01), while they did not differ between systemic sclerosis patients with sPAP < 35 mmHg and controls. Serum VEGF levels correlated to systolic pulmonary artery pressure, to diffusing capacity for carbon monoxide and to MRC dyspnea score. In multiple linear regression analysis, serum VEGF levels, MRC dyspnea score, and D_LCOwere independent predictors of systolic pulmonary artery pressure.</p> <p>Conclusion</p> <p>Serum VEGF levels are increased in systemic sclerosis patients with sPAP ≥ 35 mmHg. The correlation between VEGF levels and systolic pulmonary artery pressure may suggest a possible role of VEGF in the pathogenesis of PAH in systemic sclerosis.</p

An Operating System for Clumpy Shared Memory

Despite the pervasive expansion of parallel computer architectures and the expected exponential growth of cores on a single chip into the thousands, it is difficult to efficiently scale the performance and storage overhead of processor caches using conventional cache coherence techniques. One solution to this dilemma of scalable cache coherence is to restrict the domain of coherence to a subset of global memory. A novel technique, known as Clumpy Shared Memory (CSM), attempts to do just that by restricting either the total number of sharers that can access a coherence domain or the total number of home nodes that can do so. This work seeks to develop the software infrastructure necessary for CSM by building the operating systems support and interface for the underlying hardware implementation. We use the open-source and widely popular Linux operating system as a starting point for this OS, and provide a detailed discussion of previous and related work, design choices, methodology, and implementation