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Biomedical subjects

H Petrásová

Publications and source records attributed to H Petrásová.

11 recordsLinked to original sources
PubMed2005

High resolution electrocardiography in healthy dogs: time domain parameters and comparison of the non-stationary (Wigner distribution) versus standard stationary frequency domain analysis methods.

Fractionated heart activation can be detected as late potentials from surface recordings of signal-averaged electrocardiograms (SA ECG) which are considered as a marker of sustained ventricular tachycardia. For animal studies, reference values in time and frequency domain analyses are essentially missing. In the present study, we have established reference values in SA ECG time domain analysis and time-frequency representation of heart activation in healthy dogs. A group of 25 healthy mongrel dogs (body weight 12-15 kg) was investigated. Wigner distribution and our modification of Fast Fourier transform (FFT), gliding window FFT, was applied in SA ECG frequency domain analysis. Reference values in time domain SA ECG were established. Time and voltage criteria were adapted to short duration of heart cycle and fast voltage decrement of the QRS complex in dogs. Wigner distribution and gliding window FFT were applied in order to describe mean heart activation in the frequency domain. Contribution of higher frequencies (30-80 Hz) was detected by both frequency analysis methods in the second third of ventricular activation in healthy animals. Presented results could offer a basis for further experimental arrhythmologic studies.

Algorithms↗
PubMed2001

Signal-averaged electrocardiography in survivors of Hodgkin's disease treated with and without dexrazoxane.

Doxorubicin is one of the most effective anticancer drug, but its usefulness is limited by the risk of developing cardiomyopathy, cardiac dysfunction and ventricular arrhythmias. Dexrazoxane is used to protect against doxorubicin cardiotoxicity. It is uncertain whether the dexrazoxane-mediated cardioprotective effect will be reflected in electrophysiological properties of the heart. The aim of the present study was to evaluate the occurrence of frequency-domain signal-averaged electrocardiographic (SAECG) abnormalities of the QRS complex and the initial ST segment in patients treated with and without dexrazoxane. Thirty children and young adults 2 months - 15 years after completion of doxorubicin-containing therapy for Hodgkin's disease were evaluated with SAECG. Patients from group I (n = 13) received combined therapy with doxorubicin and dexrazoxane (DOX/DZX), patients from group II (n = 17) received doxorubicin without dexrazoxane (DOX). Using fast Fourier transformation within the QRS complex and the initial ST segment, area ratio (AR) values 40-100/0-40 Hz were calculated. Significant differences in these frequency parameters in the QRS complex between DOX/DZX group and DOX group (19.45+/-12.72 vs 46.18+/-43.06; p = 0.03) might indicate protective effect of dexrazoxane on electrophysiological myocardial properties.

Adolescent↗
PubMed1998

Signal-averaged ECG in patients after anthracycline therapy for childhood cancer.

Late cardiac complications after anthracycline therapy is an increasingly common problem among survivors of childhood cancer. Routine clinical examination may be normal, but subclinical cardiac abnormalities, which may progress with time, are documented in high percentage of these patients. Microstructural myocardial alterations may result in production of micropotential level signals (late potentials, LP) and altered frequency components of signal-averaged ECGs (SAECG). SAECG abnormalities are valuable in risk stratification of patients with various heart diseases culminating in fatal arrhythmias or heart failure. Forty-five pediatric oncologic patients (mean age 14.4 +/- 4.1 years) were included in the study. SAECG was performed 3 months-12 years (median 5.5 years) following completion of anthracycline therapy. The total cumulative doses of anthracyclines were 90-555 (median 230) mg/m2. The control group consisted of 30 healthy age-matched volunteers. LP were present in six (13.3%) patients after anthracycline therapy at 40 Hz high-pass filter setting. Using frequency-domain analysis within the QRS complex, area ratio 1 (area of 20 to 50 Hz/area of 0 to 20 Hz) and area ratio 2 (area of 40 to 100 Hz/area of 0 to 40 Hz) were calculated. Twenty (44.4%) and fourteen (31.1%) had abnormal values in area ratios 1 and 2, respectively, within the QRS complex. Area ratios 1 and 2 of patients after anthracycline therapy were significantly higher than those in control group (p = 0.0187 and p = 0.0043). Our preliminary results suggest that chemotherapy with anthracyclines, even in low dosage, is associated with increased incidence of SAECG abnormalities. The potential of this simple, noninvasive method to detect subclinical anthracycline-induced myocardial alterations and facilitate prognostic stratification of cancer survivors is promising, however, the clinical value of SAECG remains to be established in a larger and a longer study.

Adolescent↗
PubMed1996

[High-resolution electrocardiography in monitoring myocardial damage after therapy with anthracyclines in children].

BACKGROUND: Anthracycline cytostatics, widely used in oncologic practice, may induce discrete myocardial damage occasionally culminating in life-threatening cardiologic complications. The most serious clinical manifestations of anthracycline cardiotoxicity are dilated cardiomyopathy, heart failure and fatal arrhythmias. OBJECTIVES, STARTING POINT AND MAIN PURPOSE: High-resolution electrocardiography (HRECG) is one of the latest cardiologic methods, which can be promising for early identification of patients at risk of anthracycline cardiotoxicity. The aim of this study is the evaluation of the incidence of HRECG abnormalities in a group of paediatric patients treated with anthracyclines and the usefulness of HRECG for stratification of patients at risk of the clinical cardiotoxicity. PATIENTS AND METHODS: A set of 60 oncologic paediatric patients treated with anthracyclines was divided into two groups. The first group was formed by 15 patients undergoing evaluation during their anthracycline therapy (median after the last administration of antracyclines was 3.2 days). Their average age at the time of examination was 14.7 +/- 4.1 years. The total cumulative dose of antracyclines was 40-300 mg/m2 (median 150 mg/m2). The second group was formed by 45 patients who were evaluated after completing anthracycline therapy. The interval of time from the last administration of antracycline in this subgroup of patients was 3 months-12 years (median 5.5 years). Their average age at the time of HRECG examination was 14 +/- 4.1 years. The total cumulative dose of anthracyclines was 90-440 mg/m2 (median 230 mg/m2). Six patients of this group (13.3%) were treated also with mediastinal radiotherapy (18-40 Gy). 43 patients (95.5%) of second group were in complete remission, two other patients yielded a progression of their malignancy. 10 patients (22%) were examined by HRECG 2-5 times in app. two-month intervals. The control group was formed by 30 randomly selected healthy children and adolescents with normal ECG. Average age was 15.1 +/- 5.8 years. Using HRECG the time- and frequency-domain characteristics of the ECG signal were analyzed. The time-domain analysis was performed at 40-250 Hz filter. The frequency-domain analysis was performed by fast Fourier transformation (FFT), a 120 ms segment starting 20 ms before the end of the QRS complex was analyzed. The altered frequency content was expressed as the ratio of frequency areas (area ratio, AR) 20-50 Hz/0-20Hz. The average level of noise was 0.56 microV in the first group, 0.62 microV in the second group of patients and 0.68 microV in the control group. RESULTS: Abnormalities in the time-domain analysis (ventricular late potentials, VLP) were present in 2 (13.3%) of 15 patients during the anthracycline therapy in the first group and in 4 (8.8%) of 45 patients after completing therapy in the second group. No abnormalities in the time-domain analysis were detected in the control group. Using frequency-domain analysis, abnormalities in AR20-50 Hz/0-20 Hz were found in 8 (53.3%) of 15 patients of the first group, and in 11 (24.4%) of 45 patients of the second group. Significant differences were observed in the frequency parameters of the ECG signal in patients of the first group in comparison to the control group (p = 0.0018) and also when comparing the patients of the second group and the control group (p = 0.045). CONCLUSION: The HRECG results in time- and frequency-domain analyses indicate to high incidence of HRECG abnormalities in patients examined both during and after the antracycline therapy in comparison to the control group. The prognostic use of the HRECG abnormalities must be established in a larger and longer study. (Fig. 4, Tab. 2, Ref. 43.)

Adolescent↗
PubMed1994

The antihypertensive treatment and high-resolution electrocardiography.

After six months of antihypertensive treatment the regression of the initially present myocardial hypertrophy was observed: The decrease in blood pressure values is in correlation with the regression of the left ventricular hypertrophy. No correlation with parameters of high-resolution electrocardiography was noted. In one patient, a deterioration of late potentials was observed. It became more pronounced following the treatment. The monitoring of antihypertensive treatment effects by echocardiography and high-resolution electrocardiography may be therefore considered useful, especially in expected regression of the left ventricular hypertrophy. In individual cases of very outstanding regression, there exists the potential possibility of the process, resulting in the risk of arrhythmogenic substrate formation and subsequent generation of dysrhythmias.

Electrocardiography↗
PubMed1994

[Pathogenesis, prevention and detection of cardiotoxicity of anthracycline cytostatic agents].

BACKGROUND: Anthracycline antibiotics represent a part of therapeutic schemes in the treatment of a wide spectrum of malignancies. Precisely due to their cytostatic effectiveness they are being applied in spite of the risk of cardiac damage of patients. Anthracycline cardiotoxicity may culminate in potentially irreversible heart failure and fatal arrhythmias. Consequences of cardiotoxicity can complicate and shorten the lives of patients with formerly favourable prognosis of the malignant disease, and even of those that have been cured. OBJECTIVES: The aim of the presented study was to provide a review on current opinions concerning the pathophysiological mechanisms of cardiotoxicity due to anthracycline antibiotics, as well as the possibilities of cardiotoxicity prevention and detection. The procedure of cardiac monitoring of anthracycline effects is performed in order to detect the initial stage of myocardial impairment which is on the level of microstructural alterations. This requirement is mostly fulfilled by the invasive method of endomyocardial biopsy. Also the noninvasive method of high-resolution electrocardiography may reflect anatomic-electrophysiological abnormalities on the level of cardiomyocytes and interstitium. We decided to verify the usefulness of this method in the sense of the ability to detect the risk of the cardiotoxicity origin following anthracycline application. METHODS: We have repeatedly observed 34 hospitalized patients with cancer before or during chemotherapy. On the basis of high-resolution electrocardiography we have analysed the ECG signal in regard to time, frequency and time-frequency relation. RESULTS: In this study we present our initial experience with this method in combination with electrocardiographic and echocardiographic findings. In regard to the fact that the observations were of short term character we interpret our results of high-resolution electrocardiography as being preliminary. We report 4 illustrative cases of patients who independent of the dosage, yielded distinct responses toward the applied potentially cardiotoxic therapy. CONCLUSIONS: We consider the high-resolution electrocardiography in regard to its noninvasive character and low demand of time and finance to represent a perspective method of cardiac monitoring of the negative anthracycline effect. Not only ours but also the first experience in the world confirm this presupposition. By means of this method we have been able to detect initial alterations due to already low cumulative doses of anthracyclines (120 mg/m2 in a patient with ischemic heart disease and 260 mg/m2 in a patient with unimpaired myocardium prior to treatment). Our results also confirm the fact that the problem of cardiotoxicity must be necessarily strictly individualized. (Fig. 19, Ref. 80.)

Antibiotics, Antineoplastic↗