Fragmentation of bandpass-filtered QRS-complex of patients prone to malignant arrhythmia

Endt, P.; Hahlbohm, H. D.; Kreiseler, D.; Oeff, M.; Steinhoff, Uwe; Trahms, Lutz

doi:10.1007/bf02518875

Cited by 22 publications

(17 citation statements)

References 11 publications

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“…A new parametrization of QRS-fragmentation has been introduced based on the findings of the past decades in order to make it possible to apply MFI using standardized equipments used in clinical environment and under clinical routine conditions. Until now, parameterization of 1 data not available for all subjects the fragmentation was based on the quantification suggested by (Endt et al, 1998) which in principle is a measure of the magnitude and number of extrema of the averaged and bandpass filtered QRS-complex signal. This direct approach has some intrinsic limitations:…”

Section: Methods-the Fragmentation Index (Fi)mentioning

confidence: 99%

ICDs and Risk Stratification in Magnetic Field Imaging

Paolo¹,

Toennis²,

Erné³

2011

Cardiac Defibrillation - Mechanisms, Challenges and Implications

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Section: Methods-the Fragmentation Index (Fi)mentioning

confidence: 99%

ICDs and Risk Stratification in Magnetic Field Imaging

Paolo¹,

Toennis²,

Erné³

2011

Cardiac Defibrillation - Mechanisms, Challenges and Implications

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“…The number of extrema, M, and the fragmentation score, S are dimensionless quantities which are assumed to reflect fragmentation during ventricular depolarisation (BROCKMEIER et al, 1994;OEFF et al, 1995;ENDT et al 1998). This procedure enables investigation of the whole QRS complex, in a second approach, the analysis was restricted to the first 80 ms of the QRS complex excluding the information contained in the remainder of the QRS complex.…”

Section: Signal Processingmentioning

confidence: 99%

“…Also the magnetic field generated by the heart's electrical activity, measured non-invasively and without contact by the magnetocardiogram (MCG) using superconducting quantum interference devices (SQUIDs), contains diagnostic information for risk assessment (WEISSMOLLER et al, 1993;ENDT et al, 1998;HAAS et al 1999;HREN et al, 1999;MOLLER et al, 1999;).…”

mentioning

confidence: 99%

“…in this study we applied a time-domain method described by ENDT et al (1997ENDT et al ( , 1998 to both SAECG and signal averaged MCG (SAMCG) to identify patients with a known history of ventricular tachycardia (VT) in a group of post-myocardial infarction (MI) patients. The analysis was performed separately for the first 80 ms of the QRS complex in order to differentiate the diagnostic information content of the beginning and the total depolarisation period.…”

mentioning

confidence: 99%

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Identification of post-myocardial infarction patients with ventricular tachycardia by time-domain intra-QRS analysis of signal-averaged electrocardiogram and magnetocardiogram

Endt

Montonen

Mäkijärvi

et al. 2000

Med. Biol. Eng. Comput.

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A new time-domain analysis method, which quantifies ECG/MCG intra-QRS fragmentation, is applied to parts of the QRS complex to identify post-myocardial infarction patients with ventricular tachycardia. Three leads of signal-averaged electrocardiograms and nine leads of magnetocardiograms were band-pass filtered (74 Hz to 180 Hz). The filtered signals showed fragmentation in the QRS region, which was quantified by the number of peaks M and a score S, that is the product of M and the sum of the peak amplitudes. Both parameters were determined for the first 80 ms of the QRS complex and the total QRS complex in each channel. For classification, the mean-values of the parameters M and S of the three electrical leads and the nine magnetic leads were calculated. Late potential and late field analyses were performed for the same signals. 31 myocardial infarction patients were included, 20 of them with a history of documented ventricular tachycardia (VT). Identification of VT patients using the SAECG led to better results (sensitivity 95%, specificity 91%) considering the entire QRS complex than with the standard late potential analysis suggested by Simson (sensitivity 90%, specificity 73%). For the SAMCG and the entire QRS complex results using the parameters S and M are also better (sensitivity 95%, specificity 100%) than for the late field analysis (sensitivity 90% and specificity 100%). For the first 80 ms, the performance of the parameters M and S is only slightly decreased.

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“…5 However, the frequency components of the MCG higher than 50 and 60 Hz contain significant information. 2,6 For clinical diagnostics, a MCG system has to have a bandwidth wider than 100 Hz, so that further development is warranted. Electrocardiographic ͑ECG͒ instruments have bandwidths of 100 Hz or more.…”

mentioning

confidence: 99%

Second-order, high-temperature superconducting gradiometer for magnetocardiography in unshielded environment

Zhang

Panaitov

Wang

et al. 2000

Applied Physics Letters

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By employing high-temperature superconducting quantum interference device ͑SQUID͒ magnetometers, we have assembled a second-order gradiometer for magnetocardiography ͑MCG͒ in unshielded environment. With this high-temperature superconductor ͑HTS͒ SQUID system, we demonstrated its diagnostic relevance for MCG in terms of signal-to-noise ratio, spatial resolution, frequency bandwidth, rejection of environmental disturbances, and long-term stability. The electronically balanced gradiometer consists of three HTS radio-frequency SQUIDs with superconducting coplanar resonators, mounted in axial gradiometric arrangement with a baseline of 7.5 cm. The system achieves a common mode rejection for axial homogeneous fields of about 10 4 without any mechanical balancing, and a white noise about 130 fT/ͱHz at 77 K, with an 8ϫ8 mm 2 flux pickup area. MCG maps above volunteers' chests have been recorded in unshielded environment in a bandwidth of about 130 Hz. We showed the influence of several notch filters ͑suppressing the power line frequency͒ on the quality of the MCG signals. © 2000 American Institute of Physics. ͓S0003-6951͑00͒03307-6͔Magnetocardiographic ͑MCG͒ measurements using superconducting quantum interference device ͑SQUID͒ sensors are usually performed in magnetically shielded rooms, to reduce the influence of electromagnetic disturbances from the environment. 1,2 However, the high cost of such a room represents a major economic obstacle for the widespread application of magnetocardiography. Therefore, MCG gradiometer systems operating in unshielded environment would be highly desirable.High-temperature superconductor ͑HTS͒ SQUID gradiometers of adequate sensitivity ͑magnetic field resolution͒ and good disturbance rejection could offer a lower system and operating cost than their low-temperature ͑LTS͒ equivalents. Until present, first-and second-order HTS SQUID gradiometers, measuring axial or tangential fields, were demonstrated and MCG data recorded without magnetic shielding. [3][4][5] In these measurements, low-pass filters with a cutoff frequency of below 30 Hz were used to reduce the power line interference at 50 Hz, or a 60 Hz notch filter was used. 5 However, the frequency components of the MCG higher than 50 and 60 Hz contain significant information. 2,6 For clinical diagnostics, a MCG system has to have a bandwidth wider than 100 Hz, so that further development is warranted. Electrocardiographic ͑ECG͒ instruments have bandwidths of 100 Hz or more.In addition, a diagnostically meaningful map of magnetic field above the patient's chest has to be constructed of many sensing points ͑e.g., arranged in a 6ϫ6 grid͒. Hence, a sufficient long-term stability of measurement is required if sequential mapping is necessary. This is especially critical when using a single measuring point system. In this case, mapping can take, typically, about 40 min.In this letter, we present an improved second-order HTS SQUID gradiometer addressing the requirements listed above. To demonstrate the diagnostic relevance of this system,...

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Fragmentation of bandpass-filtered QRS-complex of patients prone to malignant arrhythmia

Cited by 22 publications

References 11 publications

ICDs and Risk Stratification in Magnetic Field Imaging

ICDs and Risk Stratification in Magnetic Field Imaging

Identification of post-myocardial infarction patients with ventricular tachycardia by time-domain intra-QRS analysis of signal-averaged electrocardiogram and magnetocardiogram

Second-order, high-temperature superconducting gradiometer for magnetocardiography in unshielded environment

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