Analysis of the high-frequency content in human qrs complexes by the continuous wavelet transform: An automatized analysis for the prediction of sudden cardiac death

Background: Fragmentation and delayed potentials in the QRS signal of patients have been postulated as risk markers for Sudden Cardiac Death (SCD). The analysis of the high-frequency spectral content may be useful for quantification. Methods: Forty-two consecutive patients with prior history of SCD or malignant arrhythmias (patients) where compared with 120 healthy individuals (controls). The QRS complexes were extracted with a modified Pan-Tompkins algorithm and processed with the Continuous Wavelet Transform to analyze the high-frequency content (85–130 Hz). Results: Overall, the power of the high-frequency content was higher in patients compared with controls (170.9 vs. 47.3 103nV2Hz−1; p = 0.007), with a prolonged time to reach the maximal power (68.9 vs. 64.8 ms; p = 0.002). An analysis of the signal intensity (instantaneous average of cumulative power), revealed a distinct function between patients and controls. The total intensity was higher in patients compared with controls (137.1 vs. 39 103nV2Hz−1s−1; p = 0.001) and the time to reach the maximal intensity was also prolonged (88.7 vs. 82.1 ms; p < 0.001). Discussion: The high-frequency content of the QRS complexes was distinct between patients at risk of SCD and healthy controls. The wavelet transform is an efficient tool for spectral analysis of the QRS complexes that may contribute to stratification of risk

Progress Report No. 17

Progress report of the Biomedical Computer Laboratory, covering period 1 July 1980 to 30 June 1981

Progress Report No. 16

Progress report of the Biomedical Computer Laboratory, covering period 1 July 1979 to 30 June 1980

Myocardial Perfusion and Viability

Both firstâ pass perfusion studies and imaging of delayed hyperenhancement can be combined in one patient exam. The MRI protocols for myocardial perfusion and viability assessment are presented together in this unit due to the complimentary information that is obtained with both protocols. Also, the imaging techniques used for both protocols are closely related. The first protocol assesses the functional severity of coronary artery lesions, while the second, used in addition to first basic protocol, is used in patient presents with symptoms of myocardial infarction or postâ coronary revascularization. The procedures are useful in determining the presence and extent of nonviable myocardium.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145316/1/cpmia1103.pd

Analysis of High-Frequency ECG and Mechano-Electric Coupling in Isolated Heart

Tato magisterská práce se zabývá analýzou vysokofrekvenčních složek záznamu EKG z pohledu mechano-elektrické vazby u izolovaného králičího srdce. První částí této práce je literární rešerše na zadané téma zahrnující informace o vzniku a šíření akčního potenciálu na chemické i elektrické úrovní i mechano-elektrické zpětné vazbě. Dále práce obsahuje kapitolu zabývající se tématikou průměrování signálu jako techniky ke zvýšení poměru signál-šum při analýze vysokofrekvenčních složek. V praktické části práce jsou získané poznatky aplikovány na dlouhé záznamy EKG z izolovaných králičích srdcí. Zahrnut je popis perfuzního systému podle Neelyho a jeho užití při experimentech. V realizaci byla data z 15 izolovaných králičích srdcí podrobeno analýze zkoumající přítomnost reakce systému na změnu vstupních parametrů (afterloadu a preploadu) v případě tlakově objemových dat. Výsledky byly vztaženy ke stejně získaným hodnotám z HF ECG. Dohromady tvoří popis mechano-elektriké reakce srdce na hemodynamické podněty. Výsledky byly statistisky testovány a vyhodnoceny.This master's thesis deals with the analysis of high frequency ECG from the perspective of mechano-electric coupling in isolated rabbit heart. The first part of this thesis is the literature review considering given thematics. It contains information about formation and genesis of ECG and action potential at the chemical and electric level, mechano-electric coupling. The thesis contains the chapter about signal averaging as the technique for gaining the signal-to-noise ratio when analysing HF ECG. In the part of practical application is the knowledge applied to the long recordings of isolated rabbit heart's ECG. There is the description of perfusion system according to Neely included. The realisation consists of data from 15 isolated rabbit hearts to be analysed and explored for the presence of system's reaction to the change of input parameters (preload, afterload) for the case of pressure-volume data. The results have been connected to the similar ones from HF ECG and altogether they create the description of mechano-electric coupling of heart. The reuslts have been statistically tested and evaluated.

Progress Report No. 15

Progress report of the Biomedical Computer Laboratory, covering period 1 July 1978 to 30 June 1979

Progress Report No. 19

Progress report of the Biomedical Computer Laboratory, covering period 1 July 1982 to 30 June 1983

Simultaneous ambulatory cardial and oesophageal monitoring

A method for recording and analyzing patient signals is described. The electrocardiogram and the pH in the lower oesophagus are simultaneously monitored over a 24 hour period. Signals are recorded onto cassette tape for later analysis. The pH record is analyzed for reflux episodes which are correlated with patient symptoms. The corresponding ECG episodes are checked for ischemia which appears as depression of the ST segment

Progress Report No. 14

Progress report of the Biomedical Computer Laboratory, covering period 1 July 1977 to 30 June 1978