Biomedical subjects
Publications and source records attributed to J Murin.
The therapy of AMI is aimed at the prevention of death, minimalization of discomfort caused by the disease and the reduction of the infarction focus (as soon and as markedly as possible) since the success of this step links with the later short-term as well as the long-term prognoses of the patient. (Tab. 2, Ref. 15.)
This study deals with the capabilities of body surface integral and departure maps to evaluate the chronic stage of myocardial infarction based on dividing the left ventricle into 12 segments. The effects of ventricular remodeling on electrocardiographic potential distributions are considered. A 61-year-old male patient was examined five times by body surface potential mapping during a period of 9 months after acute myocardial infarction. Integral maps were calculated for 60 ms after QRS onset and compared with mean data from a control group using departure maps. Integral maps showed a continual reduction of negative potentials in the lower half of the torso with time. The negative area covered the lower torso in the departure maps during the whole study, but its form and value changed. According to the location of the departure area, the surface projection of the scar moved from a position corresponding to inferior segments to a position corresponding to posterior segments. Its size also decreased. Echocardiographic examinations showed progressive enlargement of both ventricles with time. Therefore, the authors postulate that the changing pattern of body surface potential maps was mainly influenced by ventricular remodeling after myocardial infarction.
OBJECTIVE: An attempt to detect the 'parasitic contribution' of high frequencies in the electrocardiogram signal. DESIGN: A new method--gliding window fast Fourier transform analysis (GWFFTA)--was developed. It was applied in healthy subjects and in patients with acute myocardial infarction. SETTING: Faculty of Medicine and University Hospital. PATIENTS: The GWFFTA was used in 29 healthy volunteers and in a group of 30 patients with myocardial infarction, on day 7 to 14 after admission to a coronary unit. INTERVENTION: Noninvasive examination, performed under standard conditions. MAIN RESULTS: GWFFTA provides better reproducible results compared with 'classic' fast Fourier transform analysis. The parasitic contribution of high frequencies within QRS complex and ST segment in patients with acute myocardial infarction is independent of presence or absence of late potentials. Contribution of high frequencies are three times higher in patients with acute myocardial infarction than in healthy probands. CONCLUSIONS: GWFFTA is a reproducible method of detection of high frequencies during whole heart activation. Contribution of high frequencies in patients with acute myocardial infarction reflects the state of the entire myocardium. It is also confirmed by the lack of correlation with the presence or absence of late potentials. Late potentials are more reflective of focal changes.
Based on the presumption of the activation front splitting, the authors present their own proposal for the estimation of the myocardial electric activation course and for the detection of micropotentials 'hidden' within QRS complexes by the method of high-resolution electrocardiography. After filtration of QRS complex the values of delta RMS and those of cumulative amplitudes are calculated from the initial and from the terminal parts of QRS complexes. The presence of late potentials is reflected in a slowing down of the termination of activation course. As compared with healthy subjects, a slower rise of activation was observed in patients with myocardial infarction of the anterior wall. The curves of cumulative amplitudes rose very slowly during the first 70 ms of heart ventricle activation, explained according to the hypothesis of authors as being due to splitting of the activation front at the infarction focus. The usefulness of the proposed method was checked in patients with arterial hypertension and left ventricular hypertrophy, and in a group of patients with myocardial infarction. By the construction of cumulative amplitude curves from the onset of filtered QRS complexes, myocardial foci not reflected by 'classic' late potentials can be detected. The partial cumulative amplitudes of the QRS complex are suitable for comparative studies.