Clinical significance of high-frequency, low-amplitude electrocardiographic signals and QT dispersion in patients operated on for tetralogy of fallot

The measurement of QT dispersion in the surface electrocardiogram has been proposed as a non invasive method for assessing inhomogeneity of myocardial repolarization and has been linked to an increased risk of arrhythmic cardiac death. Several studies have evaluated the use of QTd in a wide variety of cardiac diseases and have reached conflicting conclusions regarding its clinical significance.

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Follicle size and reproductive hormone profiles during a post-weaning altrenogest treatment in primiparous sows

Reproduction Fertility and Development ◽

10.1071/rd13149 ◽

2015 ◽

Vol 27 (2) ◽

pp. 304 ◽

Cited By ~ 6

Author(s):

J. J. J. van Leeuwen ◽

M. R. T. M. Martens ◽

J. Jourquin ◽

M. A. Driancourt ◽

A. Wagner ◽

...

Keyword(s):

High Frequency ◽

Fold Increase ◽

High Amplitude ◽

Daily Administration ◽

Reproductive Hormone ◽

Diurnal Pattern ◽

Once Daily ◽

Follicular Wave ◽

Follicle Size ◽

Low Amplitude

This study investigated the endocrine background of follicle size changes during post-weaning altrenogest treatment. altrenogest-treated sows received a 20-mg dosage daily at 8.00 a.m. from Day –1 to Day 14 after weaning. On Day –1, only 3/13 altrenogest-treated sows showed LH pulses compared with 8/8 control sows (P = 0.001). On Day 0, control sows showed a typical high frequency–low amplitude LH pattern, indicative for recruitment of oestrogenic follicles. In altrenogest-treated animals on Day 0, half of the sows showed high frequency–high amplitude pulses from 4–5 h after weaning. In altrenogest-treated sows, average follicle size increased from 3.1 ± 0.5 mm on Day 0 to 4.4 ± 0.6 mm on Day 5, then decreased to 3.7 ± 0.5 mm on Day 7 and stabilised thereafter. FSH and oestradiol (E2) concentrations showed a distinct diurnal pattern; high at 7.00 a.m. and low at 3.00 p.m. E2 concentrations (7.00 a.m.) showed a 2.5-fold increase from Day –1 to Day 2, and subsequently a 2-fold decline to reach a plateau at Day 8. FSH concentrations reached maximum levels by Day 5 and slowly declined afterwards. In conclusion, once-daily administration of altrenogest starting one day before weaning delays the weaning-induced increase in LH pulses. Although FSH and follicle size increase until Day 5 after weaning, follicle E2 production already decreased from Day 2 after weaning. Post-weaning altrenogest treatment thus results in a follicular wave of follicles that lose oestrogenic competence at Day 2 after weaning, presumably related to the changed LH dynamics during altrenogest treatment.

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Clinical significance of QT dispersion after exercise in patients with previous myocardial infarction

International Journal of Cardiology ◽

10.1016/s0167-5273(98)00120-x ◽

1998 ◽

Vol 65 (3) ◽

pp. 255-260 ◽

Cited By ~ 4

Author(s):

Guo-Long Yu ◽

Ian-Ren Cheng ◽

Shui-Ping Zhao ◽

Han-Ping Zhuang ◽

Xiao-Yuan Cai

Keyword(s):

Myocardial Infarction ◽

Clinical Significance ◽

Qt Dispersion ◽

Previous Myocardial Infarction

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Influence of low amplitude/high frequency relative sea-level changes in a wave-dominated estuary (Miocene), São Luis Basin, northern Brazil

Sedimentary Geology ◽

10.1016/s0037-0738(00)00046-4 ◽

2000 ◽

Vol 133 (3-4) ◽

pp. 295-324 ◽

Cited By ~ 27

Author(s):

D de Fátima Rossetti

Keyword(s):

Sea Level ◽

High Frequency ◽

Sea Level Changes ◽

Relative Sea Level ◽

Northern Brazil ◽

Low Amplitude

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Upward shallowing platform cycles: A response to 2.2 billion years of low-amplitude, high-frequency (Milankovitch band) sea level oscillations

Paleoceanography ◽

10.1029/pa001i004p00403 ◽

1986 ◽

Vol 1 (4) ◽

pp. 403-416 ◽

Cited By ~ 31

Author(s):

J. P. Grotzinger

Keyword(s):

Sea Level ◽

High Frequency ◽

Sea Level Oscillations ◽

Low Amplitude

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Evaluation of cardiac autonomic function using heart rate variability in children with acute carbon monoxide poisoning

Cardiology in the Young ◽

10.1017/s1047951117000944 ◽

2017 ◽

Vol 27 (9) ◽

pp. 1662-1669 ◽

Cited By ~ 1

Author(s):

Cagdas Vural ◽

Ener Cagri Dinleyici ◽

Pelin Kosger ◽

Ozge Bolluk ◽

Zubeyir Kilic ◽

...

Keyword(s):

Heart Rate ◽

Carbon Monoxide ◽

Heart Rate Variability ◽

High Frequency ◽

Autonomic Function ◽

Spectral Power ◽

Carbon Monoxide Poisoning ◽

Low Frequency ◽

Qt Dispersion ◽

Cardiac Autonomic Function

AbstractIntroductionCarbon monoxide poisoning may cause myocardial toxicity and cardiac autonomic dysfunction, which may contribute to the development of life-threatening arrhythmias. We investigated the potential association between acute carbon monoxide exposure and cardiac autonomic function measured by heart rate variability.MethodThe present study included 40 children aged 1–17 years who were admitted to the Pediatric Intensive Care Unit with acute carbon monoxide poisoning and 40 healthy age- and sex-matched controls. Carboxyhaemoglobin and cardiac enzymes were measured at admission. Electrocardiography was performed on admission and discharge, and 24-hour Holter electrocardiography was digitally recorded. Heart rate variability was analysed at both time points – 24-hour recordings – and frequency domains – from the first 5 minutes of intensive care unit admission.ResultsTime domain and frequency indices such as high-frequency spectral power and low-frequency spectral power were similar between patient and control groups (p>0.05). The ratio of low-frequency spectral power to high-frequency spectral power was significantly lower in the carbon monoxide poisoning group (p<0.001) and was negatively correlated with carboxyhaemoglobin levels (r=−0.351, p<0.05). The mean heart rate, QT dispersion, corrected QT dispersion, and P dispersion values were higher in the carbon monoxide poisoning group (p<0.05) on admission. The QT dispersion and corrected QT dispersion remained longer in the carbon monoxide poisoning group compared with controls on discharge (p<0.05).ConclusionThe frequency domain indices, especially the ratio of low-frequency spectral power to high-frequency spectral power, are useful for the evaluation of the cardiac autonomic function. The decreased low-frequency spectral power-to-high-frequency spectral power ratio reflects a balance of the autonomic nervous system, which shifted to parasympathetic components.

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Vibrational Fatigue Analysis of a Strain Loading Using the Frequency and Wavelet Filtering Methods

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.462-463.124 ◽

2011 ◽

Vol 462-463 ◽

pp. 124-129

Author(s):

Shahrum Abdullah ◽

Edisah Putra Teuku ◽

Zaki Nuawi Mohd. ◽

Mohd. Nopiah Zulkifli

Keyword(s):

High Frequency ◽

Filter Design ◽

High Amplitude ◽

Morlet Wavelet ◽

Wavelet Filtering ◽

Pass Filter ◽

Low Pass Filter ◽

Automotive Components ◽

Low Pass ◽

Low Amplitude

This paper presents a comparison work between the filtering methods of fatigue strain loadings using the frequency spectrum and the wavelet transform (WT), in which a raw loading signal can be simplified for purpose of simulation. For this reason, the Fast Fourier Transform (FFT) and the Morlet wavelet algorithms were used in order to transform the vibrational fatigue time series into the frequency domain signal, leading to the observation of the frequency characteristics of the signal. To retain high amplitude cycles in the FFT algorithm, a low pass filter technique was applied to remove the high frequency signals with small amplitude that are non-damaging. The departure of high frequency information smoothed the low amplitude cycles at high frequency events in the fatigue signal. The Butterworth filter was selected as the most efficient filter design as it retained most of the fatigue damage and also had the capability to remove 30 % of the original low amplitude cycles. On the other hand, the Morlet wavelet managed to remove 64 % of the original 59 second signal. This wavelet filtering method removed 34 % more than the similar procedure applied through the FFT approach. Hence, this fatigue data summarising algorithm can be used for studying the durability characteristics of automotive components.

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