Biomedical subjects

Selwyn P Wong

Publications and source records attributed to Selwyn P Wong.

5 recordsLinked to original sources

PubMed2007

Reliability of echocardiographic indices of dyssynchrony.

BACKGROUND: Echocardiographic indices of dyssynchrony are increasingly used to select candidates for cardiac resynchronization therapy. For widespread screening of heart failure patients, such variables need to be comparable when evaluated by different operators using different equipment. OBJECTIVE AND METHODS: To evaluate the reproducibility and obtainability of echocardiographic indices of mechanical dyssynchrony, we studied 40 subjects stratified according to QRS morphology and systolic function. Two echocardiograms were performed on each patient by different sonographers on different machines and each study was analyzed by two observers. RESULTS: All blood-pool and tissue Doppler indices of dyssynchrony were obtainable in over 97% of cases. Blood-pool Doppler measures were the most reproducible indices of intraventricular dyssynchrony (aortic ejection delay) and interventricular dyssynchrony (aortopulmonary difference in ejection delay). For annular tissue Doppler delays, the time to peak velocity was consistently more reproducible than the time to velocity onset. CONCLUSION: Differences in the reliability of echocardiographic indices may affect their suitability as screening tests for dyssynchrony.

Arrhythmias, Cardiac↗

PubMed2006

Longitudinal left ventricular contractile dysfunction after exercise in aortic stenosis.

OBJECTIVE: To determine whether longitudinal left ventricular systolic function measured by Doppler tissue imaging (DTI) after exercise can identify early left ventricular dysfunction in asymptomatic patients with moderate-severe aortic stenosis. DESIGN: Case-control study. SETTING: Outpatient cardiology departments. PATIENTS: 20 patients with aortic stenosis, with or without equivocal symptoms, a peak aortic valve velocity > or =3 m/s, and left ventricular ejection fraction >50% and 15 aged-matched normal controls. INTERVENTIONS: Echocardiogram performed at rest and immediately after treadmill exercise. MAIN OUTCOME MEASURES: The peak systolic velocity of the lateral mitral annulus (S') by DTI at rest and immediately after exercise, exercise capacity, exercise systolic blood pressure and the plasma level of B-type natriuretic peptide (BNP). RESULTS: For patients with aortic stenosis, mean (SD) aortic valve area was 0.95 (0.3) cm(2). At rest, S' was similar for patients with aortic stenosis and controls, respectively (8.5 (1.5) vs 9.1 (1.8) cm/s, p = 0.15). However, after exercise, S' (12.2 (3.2) vs 17 (2.8) cm/s, p<0.001) and the increase in S' between rest and exercise (4 (3) vs 7.9 (1.5) cm/s, p<0.001) were lower in patients with aortic stenosis. In patients with aortic stenosis, a smaller increase in S' after exercise was associated with lower exercise capacity (r = 0.5, p = 0.02), a smaller increase in exercise systolic blood pressure (r = 0.6, p = 0.005) and higher plasma level of BNP (r = 0.66, p = 0.002). CONCLUSION: In asymptomatic patients with moderate-severe aortic stenosis a lower than normal increase in peak systolic mitral annular velocity after treadmill exercise is a marker of early left ventricular systolic dysfunction.

Aged↗

PubMed2004

Relation of left ventricular sphericity to 10-year survival after acute myocardial infarction.

After ST-elevation myocardial infarction, the association between left ventricular sphericity (measured by biplane ventriculography) and survival rate at a median of 6.5 years was determined in 825 patients. The highest tertile of sphericity (vs the lowest and middle tertiles) was associated with a decreased 10-year survival rate in patients who had anterior myocardial infarction (p = 0.002), inferior myocardial infarction (p = 0.011), Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow (p = 0.005), or TIMI grade 0 to 2 flow (p = 0.001) in the infarct artery. The independent multivariate predictors of a 10-year survival rate were ejection fraction (p = 0.002), treadmill exercise duration (p = 0.004), biplane left ventricular sphericity index (p = 0.032), age (p = 0.043), and end-systolic volume index (p = 0.047), but not TIMI flow grade.

Cineangiography↗

PubMed2003

Rapid and accurate left ventricular surface generation from three-dimensional echocardiography by a catalog based method. Rapid LV surface generation by three-dimensional echo.

BACKGROUND: Quantitative analysis from three-dimensional (3D) echocardiography requires accurate reconstruction of left ventricular (LV) surfaces. This currently requires time-consuming manual image tracing. We describe and validate an alternative rapid method of generating LV surfaces. METHODS: A 3D-image set is acquired using transthoracic scanning. Images from five standard echo views are displayed and border points selected where anatomic landmarks are well defined. A LV surface is reconstructed as a convex weighted sum of LVs from a catalog of 80 LVs. The intersections of the surface with the five views are presented on these images. The routine may be rerun until the LV surface matches the images. One LV surface is generated in 3 min +/- 27 s. In 41 studies (19 normal, 15 previous infarction, seven cardiomyopathy) the volumes of the catalog-fit endocardial and epicardial surfaces were compared with volumes from surfaces reconstructed from full manual tracing. RESULTS: Over a wide range of LV volumes and ejection fraction (EF), the catalog-fit results correlated closely to those from manual tracing: end-diastolic volume (194 +/- 99 vs. 204 +/- 110 ml, y = 0.93x, R2 = 0.99, SEE = 19 ml, p < 0.001), end-systolic volume (122 +/- 95 vs. 131 +/- 106 ml, y = 0.92x, R2 = 0.99, SEE = 13 ml, p < 0.001), EF (42 +/- 16 vs. 42 +/- 15%, y = x, R2 = 0.99, SEE = 4%, p < 0.001) and mass (220 +/- 88 vs. 204 +/- 86 g, y = 1.1x, R2 = 0.99, SEE = 24 g, p < 0.001). The endocardial catalog surface was generated from an average of 20 points and three computational runs for both end-diastole and end-systole. CONCLUSIONS: The catalog method of LV reconstruction from 3D-echo provides accurate measurement of volume, EF and mass. The speed of the method is a major advantage.

Echocardiography, Three-Dimensional↗

PubMed2003

Three-dimensional assessment of two-dimensional technique for evaluation of right ventricular function by tricuspid annulus motion.

BACKGROUND: Measurement of tricuspid annulus motion (TAM) is an easy way to estimate right ventricular ejection fraction (RVEF). However the accuracy of two-dimensional (2-D) methods for analyzing the three-dimensional (3-D) structure of the tricuspid annulus has not been evaluated. OBJECTIVE: This study evaluated the accuracy with which 2-D measurements of TAM reflect RVEF using 3-D reconstructions of the heart at end diastole (ED) and end systole (ES). METHODS: 2-D echocardiographic studies were performed on 12 subjects and used to reconstruct the RV and tricuspid annulus in 3-D at ED and ES. Measurements of TAM from medial and lateral positions on the annulus were selected from the standard echocardiographic apical four-chamber view. The minimum and maximum possible TAM values, RV volumes, and movement of the apex of the heart along the trajectory of TAM were calculated from the 3-D reconstructions. RESULTS: TAM correlated highly with RVEF (r > or = 0.90). Values found by 2-D and 3-D techniques were not significantly different. Correcting TAM for apex motion did not improve correlation. Summation of medial and lateral TAM data increased correlation values slightly relative to lateral TAM alone. Regional aberrant contractility degraded the predictive value of TAM. CONCLUSION: Estimation of RVEF from 2-D echo measurement of TAM is accurate, especially when medial and lateral TAM are summed, except in patients with severe apical RV dysfunction.

Adult↗