A new curve registration technique for the analysis of T waves shapes.

T waves properties are not usually fully exploited when analyzing its profile variation within a set of records. An affine transform of the temporal support is a good candidate for the modeling of this variation. Based on this assumption, we propose here a new framework that provides an estimation of the reference T wave and the parameters of the affine functions. To achieve this task, the domain of the inverse normalized integral is investigated, allowing a compact description of the dataset. As a straightforward tool, the Principal Component Analysis is shown to be efficient in this do- main. This approach is illustrated by analyzing a set of T waves recorded during Dipyridamol infusion and during angioplasty.

ECG variability contour--a reference for evaluating the significance of amplitude ECG changes in two states.

The sensitivity of the standard 12-lead ECG for detecting myocardial ischemia is low perhaps because in the printed ECG only three to five complexes are examined, only absolute amplitude (voltage) criteria are used, and amplitude changes are sought only in the ST segment and T wave regions. A computerized method is proposed for evaluating the significance of ECG amplitude changes detected in one state compared with another (e.g. rest and stress). Amplitude changes were considered significant if they were consistently greater than the 'ECG variability contour' (EVC), which is a graphic measure introduced in this study, calculated from the reference ECG signal. Rest and stress simulation ECG (SECG) were constructed. Mean rest SECG complex was subtracted from rest and stress SECG complexes to result in rest and stress residue matrices, respectively. The percentage of the normalized cumulative sum (NCS) of the residues during stress (and rest) lying outside the EVC served as a measure for evaluating ECG changes associated with stress (and rest). With this method, amplitude changes of magnitude similar to that of the noise, which were difficult to detect visually, were easily detected and accurately allocated to the component of the ECG complex where they occurred. The proposed method may be useful in cases where amplitude changes are too subtle and thus overlooked or not detected by the standard examination of three to five complexes or underestimated due to unmet clinical (voltage) criteria, or occur in ECG components that are not regularly examined.

Non-invasive computerised detection of acute coronary occlusion.

The goal of this study was to evaluate the role of a computerised, non-invasive ECG method for detecting acute coronary occlusion (ACO). Ninety-five standard ECG leads were recorded, before and during ACO, from 18 patients undergoing balloon angioplasty. ECG amplitude and derivative parameters were calculated for the ORS, ST and T components of the ECG signal, before and during ACO. Results were obtained for each lead. Sensitivity of the standard visual ECG analysis for detecting ACO was 48%, whereas the percentage of conventional ECG changes during baseline was 14%. For the best ECG parameter, the amplitude parameter of the ORS component, sensitivity was 82%, and the percentage of parameter changes during baseline was 20%. The sensitivity for detecting ACO with five of the six ECG parameters studied was greater than that of the standard visual analysis. Ischaemic changes were detected in 4.3 +/- 1.6 leads per patient using the amplitude parameter of the ORS component, whereas, with the standard visual analysis, 2.5 +/- 2.1 leads demonstrated such changes (p<0.001). Results were then summarized per patient. The standard visual ECG analysis detected ACO in 15 of 18 patients (83%), if at least one lead showed ischaemic changes. The computerised analysis detected ACO in all 18 patients using the same criterion. The sensitivity of the computerised method for detecting ACO in the clinical setting of angioplasty was greater than that of the standard visual analysis. It is suggested that the computerised method may be useful for detecting myocardial ischaemia in other clinical settings of acute myocardial ischaemia.

Exercise stress testing, myocardial perfusion imaging and stress echocardiography for detecting restenosis after successful percutaneous transluminal coronary angioplasty: a review of performance.

When chest symptoms recur in a patient who underwent percutaneous transluminal coronary angioplasty (PTCA), it is necessary to rule out restenosis (R). Three main noninvasive tests suggest the presence of R: exercise stress test (XT), myocardial perfusion imaging (MPI) and stress echocardiography (s-echo). The objectives of this review were: (1) to estimate the pretest probability of R as a function of time after PTCA in symptomatic patients and (2) to obtain an approximation of the diagnostic parameters of the XT, MPI and s-echo for detecting R. A MEDLINE search (English-language, years: 1980-2001) was conducted to identify studies examining post-PTCA functional testing for diagnosing R. Data from the studies were pooled. Comparing studies was often difficult due to varying methodology in the studies. Pretest probability of R in symptomatic patients increases in a nonlinear fashion from 20% or less at 1 month, to nearly 90% at 1-year postangioplasty. The approximated accuracy of the XT, MPI, and s-echo for detecting R was 62, 82 and 84%, respectively. During the first month after PTCA, none of the noninvasive modalities is able to accurately detect R. Late (7-9 months) after PTCA, the pretest probability of R is high and therefore the noninvasive measure may be spared. Our analysis suggests that MPI and s-echo should be preferred over the XT for diagnosing R.

Depression, hopelessness, and self-esteem: accounting for suicidality in adolescent psychiatric inpatients.

The present study was designed to examine depression, hopelessness, and self-esteem as related to suicidal behavior in three groups of depressed adolescent psychiatric inpatients. Depressed adolescents who had never attempted suicide were compared to depressed adolescents who had attempted suicide once and to depressed adolescents who had attempted suicide on several different occasions. Results showed that suicidal adolescents experienced significantly greater depression and hopelessness than did the nonsuicidal adolescents. However, all three groups of depressed adolescents reported similar low levels of self-esteem. Measures of depression and hopelessness were useful in classifying the adolescents based on their suicidal behavior. Results suggest that the treatment of suicidal adolescents could benefit from strategies that focus on reducing feelings of depression and hopelessness.

[Ring-valve abscess--a diagnostic challenge].

Infective endocarditis is a life-threatening disease which may be complicated by ring-valve abscess. Since this complication increases morbidity and mortality early diagnosis is important. Pericardial effusion complicating infective endocarditis is uncommon and should raise suspicion of the presence of an abscess. We describe 2 patients admitted for infective endocarditis and pericarditis. In both, ring-valve abscess was suspected on clinical grounds. At surgery there was pathological confirmation of the diagnosis. Both patients underwent successful aortic valve replacement with complete recovery. Controlled trials are providing increasing evidence for the superiority of transesophageal echocardiography in detecting valvular vegetations. Moreover, it is the most accurate means of detecting ring-valve abscess in cases of infective endocarditis. In view of these advantages, we propose the use of transesophageal echocardiography in every case of infective endocarditis.