Accuracy of subjective and computer-assisted assessments of angiographic left ventricular regional wall motion

Validation of the local shortening function as assessed by nonfluoroscopic electromechanical mapping: a comparison with computerized left ventricular angiography

BACKGROUND

Nonfluoroscopic electromechanical mapping (NEM) has been proposed as a new technique for the evaluation of electrical and mechanical functioning of the myocardium. In this system, linear local shortening (LLS) is the parameter used for assessment of local mechanical properties. To validate this parameter, we compared LLS with regional wall motion (RWM) data derived from contrast left ventriculograms acquired in the same patients.

METHODS AND RESULTS

Angiographic left ventricular RWM was analyzed using the area-length method. The right anterior oblique view was divided in five segments, the left anterior oblique view in two. Through a comparison of enddiastolic and endsystolic areas drawn from a computer-defined central point to the respective wall delineation, RWM was calculated as change in area. In the first approach, we compared area changes to comparable NEM segments. In the second part of the study, LLS values for normokinetic, hypokinetic, akinetic and dyskinetic segments were correlated to the change in angiographic RWM. In the first approach, the overall comparison of segments yielded a correlation coefficient of 0.67 (P<0.0005). In the second part of the study, differences in LLS values between dyskinetic (LLS=-3.68+/-8.86%), akinetic (2.84+/-3.96%), hypokinetic (9.35+/-4.27%) and normokinetic (13.66+/-7.98%) segments were highly significant (overall ANOVA: P<0.0005).

CONCLUSION

NEM is a powerful tool for invasive electromechanical assessment of myocardial function.

Tracking geometrical descriptors on 3-D deformable surfaces: application to the left-ventricular surface of the heart

Motion and deformation analysis of the myocardium are of utmost interest in cardiac imaging. Part of the, research is devoted to the estimation of the heart function by analysis of the shape changes of the left-ventricular endocardial surface. However, most clinically used shape-based approaches are often two-dimensional (2-D) and based on the analysis of the shape at only two cardiac instants. Three-dimensional (3-D) approaches generally make restrictive hypothesis about the actual endocardium motion to be able to recover a point-to-point correspondence between two surfaces. The present work is a first step toward the automatic spatio-temporal analysis and recognition of deformable surfaces. A curvature-based and easily interpretable description of the surfaces is derived. Based on this description, shape dynamics is first globally estimated through the temporal shape spectra. Second, a regional curvature-based tracking approach is proposed assuming a smooth deformation. It combines geometrical and spatial information in order to analyze a specific endocardial region. These methods are applied both on true 3-D X-ray data and on simulated normal and abnormal left ventricles. The results are coherent and easily interpretable. Shape dynamics estimations and comparisons between deformable object sequences are now possible through these techniques. This promising framework is a suitable tool for a complete regional description of deformable surfaces.

Comparison of models for quantitative left ventricular wall motion analysis from two-dimensional echocardiograms during acute myocardial infarction

To develop quantitative analysis of regional left ventricular wall motion in the absence of a gold standard, an objective statistical measure to compare models of wall motion is described. This measure can be derived from wall motion analysis of subgroups of patients with different patterns of wall motion. A priori knowledge of the exact localization of wall motion abnormalities is not needed. Two-dimensional echocardiograms were analyzed from 79 patients with myocardial infarction. The following 4 models were compared: Model I was based on the descent of the base toward the stable apex during systole. Models II and III measured area reduction with fixed- and floating-reference systems, respectively. Model IV was the centerline model. Classification by the electrocardiogram of the myocardial infarction as anterior (n = 37), posterior (n = 17) and inferior (n = 25) provided the a priori probability for classification of myocardial infarction. The a posteriori probability for classification of myocardial infarction was derived from the detection of wall motion abnormalities by echocardiographic analysis. The mean difference between a posteriori and a priori probability is a measure for the diagnostic value of the model, and was measured for 200 regions/patient. Use of the described measure revealed model I to be the most informative model and model III the least informative. Thus, the described statistical measure contributes to the development of regional wall motion analysis.

Reference systems in echocardiographic quantitative wall motion analysis with registration of respiration

Registration of respiration allows analysis at the end-expiratory phase and may thus favor the use of the fixed-reference system versus the floating-reference system in echocardiographic quantitative wall motion analysis. Analysis is performed on two-dimensional echocardiograms of 44 normal subjects, 38 patients with anterior myocardial infarction, and 17 patients with posterior myocardial infarction. Two different models for wall motion analysis are applied, each using the fixed-reference system and the floating-reference system, respectively. In patients with anterior myocardial infarction, the fixed-reference system indicates severe wall motion abnormalities at the anterior, septal, and apical walls, whereas the floating-reference system indicates less severe wall motion abnormalities almost equally at every wall. In patients with posterior myocardial infarction, the fixed-reference system indicates severe wall motion abnormalities at the posterior wall, whereas the floating-reference system indicates less severe wall motion abnormalities almost equally at every wall. These findings indicate that the fixed-reference system is superior to the floating-reference system in quantification of wall motion of end-expiratory two-dimensional echocardiograms.