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ECG Testing (ecg + testing)

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Medical Sciences	100%

Selected Abstracts

Assessment of Noise in Digital Electrocardiograms

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 4 2002
VELISLAV BATCHVAROV
BATCHVAROV, V., et al.: Assessment of Noise in Digital Electrocardiograms. Technically related noise in 12-lead ECGs recorded with ambulatory recorders has never been systematically compared with that in ECGs recorded with conventional ECGs. This study compared serial 10-second ECGs obtained in ten healthy men, age 22,45 years, who were recorded in the supine resting position using a (1) MAC VU recorder, (2) digital ambulatory SEER MC recorder with a Multi-Link detachable ECG cable, and (3) digital ambulatory SEER MC recorder with a light ambulatory ECG cable. In each ECG, averaged sinus rhythm cycles of the entire recording were realigned with the native signal and subtracted. The resulting "residuum" was quantified by computing its standard deviation and root mean square of successive differences (RMSSD). While the RMSSD residuum values were significantly lower with the MAC VU recorder (6.27 ± 0.98 ,V) than with the SEER MC recorder with either ECG cables (7.29 ± 1.31 and 7.17 ± 1.31 ,V, P < 0.003 and p < 0.02), the difference was practically negligible and there was no detectable difference in the standard deviation residuum values. The study concludes that valid ECG investigations of serial ECG testing may be conducted using the ambulatory SEER MC recorders providing the biological sources of ECG noise are controlled. The available technology for noise assessment suggests that studies involving advanced analysis of serial ECGs (e.g., of drug related changes), should incorporate objective characterisation of ECG quality. [source]

Dynamics and Rate-Dependence of the Spatial Angle between Ventricular Depolarization and Repolarization Wave Fronts during Exercise ECG

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2010
Tuomas Kenttä M.Sc.
Background: QRS/T angle and the cosine of the angle between QRS and T-wave vectors (TCRT), measured from standard 12-lead electrocardiogram (ECG), have been used in risk stratification of patients. This study assessed the possible rate dependence of these variables during exercise ECG in healthy subjects. Methods: Forty healthy volunteers, 20 men and 20 women, aged 34.6 ± 3.4, underwent an exercise ECG testing. Twelve-lead ECG was recorded from each test subject and the spatial QRS/T angle and TCRT were automatically analyzed in a beat-to-beat manner with custom-made software. The individual TCRT/RR and QRST/RR patterns were fitted with seven different regression models, including a linear model and six nonlinear models. Results: TCRT and QRS/T angle showed a significant rate dependence, with decreased values at higher heart rates (HR). In individual subjects, the second-degree polynomic model was the best regression model for TCRT/RR and QRST/RR slopes. It provided the best fit for both exercise and recovery. The overall TCRT/RR and QRST/RR slopes were similar between men and women during exercise and recovery. However, women had predominantly higher TCRT and QRS/T values. With respect to time, the dynamics of TCRT differed significantly between men and women; with a steeper exercise slope in women (women, ,0.04/min vs ,0.02/min in men, P < 0.0001). In addition, evident hysteresis was observed in the TCRT/RR slopes; with higher TCRT values during exercise. Conclusions: The individual patterns of TCRT and QRS/T angle are affected by HR and gender. Delayed rate adaptation creates hysteresis in the TCRT/RR slopes. Ann Noninvasive Electrocardiol 2010;15(3):264,275 [source]

The Predictive Value of Exercise QRS Duration Changes for Post-PTCA Coronary Events

ANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 1 2003
Shai Efrati
Background: The sensitivity and predictive values of exercise ECG testing using ST-T criteria after percutaneous transluminal coronary angioplasty (PTCA) are low, precluding its routine use for screening for restenosis. The predictive value of QRS duration criteria during exercise testing (ET) ECG after PTCA for future coronary events has not been reported. The aim of the study was to compare QRS duration changes with ST-T criteria during ET, as a predictor of coronary events after PTCA. Methods: A prospective study of 206 consecutive patients who underwent ET at a mean of 34 ± 14 days after their first PTCA, and were the followed for a mean of 23 ± 9 months. Patients were divided by QRS duration into two groups,Q1: ischemic response (QRS duration prolongation of more than 3 ms relative to the resting duration), and Q2: normal response (QRS duration shortening or without change from resting duration). Patients were also divided by their ST-T response, S1: ischemic response, and S2: normal response. Results: During follow-up 52 patients (58%) experienced restenosis or MI, or underwent CABG,Q1: 44 (85%), Q2: 8(15%) (P < 0.0002), S1: 8 (15%), S2: 44 (85%), (P < 0.641), two patients died,Q1: 1 (1%) and Q2: 1 (1%). For QRS and ST-T, the relative risk of having at least one of the coronary events was 4.02 (CI 2.1,9.9) versus 1.13 (CI 0.8,2.9), respectively. The sensitivity for future coronary events was 85% and 52% and the specificity was 48% and 98% for the QRS and ST-T criteria, respectively. Conclusion: QRS prolongation during peak ET ECG after PTCA is a more sensitive marker than ST-T criteria for detection of patients at risk for later coronary events. [source]

Sixty-four,slice Computed Tomography of the Coronary Arteries: Cost,Effectiveness Analysis of Patients Presenting to the Emergency Department with Low-risk Chest Pain

ACADEMIC EMERGENCY MEDICINE, Issue 7 2008
Rahul K. Khare MD
Abstract Objectives:, The aim was to use a computer model to estimate the cost,effectiveness of 64-slice multidetector computed tomography (MDCT) of the coronary arteries in the emergency department (ED) compared to an observation unit (OU) stay plus stress electrocardiogram (ECG) or stress echocardiography for the evaluation of low-risk chest pain patients presenting to the ED. Methods:, A decision analytic model was developed to compare health outcomes and costs that result from three different risk stratification strategies for low-risk chest pain patients in the ED: stress ECG testing after OU care, stress echocardiography after OU care, and MDCT with no OU care. Three patient populations were modeled with the prevalence of symptomatic coronary artery disease (CAD) being very low risk, 2%; low risk, 6% (base case); and moderate risk, 10%. Outcomes were measured as quality-adjusted life years (QALYs). Incremental cost,effectiveness ratios (ICERs), the ratio of change in costs of one test over another to the change in QALY, were calculated for comparisons between each strategy. Sensitivity analyses were conducted to test the robustness of the results to assumptions regarding the characteristics of the risk stratification strategies, costs, utility weights, and likelihood of events. Results:, In the base case, the mean (±standard deviation [SD]) costs and QALYs for each risk stratification strategy were MDCT arm $2,684 (±$1,773 to $4,418) and 24.69 (±24.54 to 24.76) QALYs, stress echocardiography arm $3,265 (±$2,383 to $4,836) and 24.63 (±24.28 to 24.74) QALYs, and stress ECG arm $3,461 (±$2,533 to $4,996) and 24.59 (±24.21 to 24.75) QALYs. The MDCT dominated (less costly and more effective) both OU plus stress echocardiography and OU plus stress ECG. This resulted in an ICER where the MDCT arm dominated the stress echocardiography arm (95% confidence interval [CI] = dominant to $29,738) and where MDCT dominated the ECG arm (95% CI = dominant to $7,332). The MDCT risk stratification arm also dominated stress echocardiography and stress ECG in the 2 and 10% prevalence scenarios, which demonstrated the same ICER trends as the 6% prevalence CAD base case. The thresholds where the MDCT arm remained a cost-saving strategy compared to the other risk stratification strategies were cost of MDCT, <$2,097; cost of OU care, >$1,092; prevalence of CAD, <70%; MDCT specificity, >65%; and a MDCT indeterminate rate, <30%. Conclusions:, In this computer-based model analysis, the MDCT risk stratification strategy is less costly and more effective than both OU-based stress echocardiography and stress ECG risk stratification strategies in chest pain patients presenting to the ED with low to moderate prevalence of CAD. [source]