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Biomedical subjects

J Silny

Publications and source records attributed to J Silny.

At least 73 records · Page 4Linked to original sources
PubMed1985

[Electrocardiogram in acute anterior wall infarct after restoration of the blood supply].

Changes in QRS complexes and ST-T segments were measured in 70 patients after acute anterior-wall myocardial infarction. Intracoronary streptokinase infusion was undertaken in the acute phase in 58 patients, 12 other patients treated conventionally without infusion serving as controls. Precordial ECG mapping employed 48 unipolar precordial leads. If recanalization of an occluded coronary artery was achieved, there was a significant rise in R amplitude (sum of R-wave amplitudes in the 48 leads) from 12.4 +/- 10.9 to 16.2 +/- 11.2 mV, within a period of up to four months after the acute stage. If thrombolysis failed or only conventional treatment had been practised, there was no rise in R-wave amplitude. Renewed occlusion of a vessel previously re-opened by streptokinase infusion produced a reduction in R-wave amplitude from 14.0 +/- 13.0 to 9.8 +/- 11.0 mV. The S-T segment elevation regressed immediately after recanalization of the coronary artery. The S-T segments were iso-electric after four months. Re-occlusion caused renewed S-T segment elevation up to monophasic form. Precordial ECG mapping is thus well suited for serial controls after various re-perfusion measures.

Electrocardiography↗
PubMed1985

Myocardial infarction and thrombolysis. Electrocardiographic short term and long term results using precordial mapping.

In a consecutive series of 56 patients with acute myocardial infarction, ST segment depression and elevation in the electrocardiographic limb leads I, II, and III were summated for each patient before and immediately after intracoronary streptokinase infusion and the results compared with the angiographic findings. Forty three patients had angiographically confirmed reperfusion of an initially occluded vessel and showed a significant decrease in summated ST shift. The ST segment changes in the limb leads virtually returned to normal in all 43 patients, and in most, inverted T waves developed. Thrombolysis was unsuccessful in 10 patients, and the infarct related coronary artery was already patent in three. When these two groups are combined, all 13 patients without reperfusion showed no significant change in summated ST segment shift. During percutaneous transluminal angioplasty inflation of the balloon in the vessel that was previously occluded simulated reocclusion and was followed by new ST elevation if the artery supplied viable myocardium. In a further consecutive study of 54 patients with anterior myocardial infarction, the precordial R waves and Q waves were studied over the four to six months following infarction using a standardised 48 electrode mapping system. All patients underwent a repeat angiogram after four to six months. In 36 patients the infarct related vessel was patent. They showed a significant mean increase in summated precordial R wave amplitude and a reduction in the mean number of precordial leads without R waves. In 18 patients with unsuccessful thrombolysis or reocclusion there was a further reduction in mean summated R wave amplitude and an increased number of precordial leads not showing R waves. Precordial R wave mapping seems to be a valuable non-invasive method of assessing the salvage of myocardium after reperfusion and the damage caused by reocclusion. Loss of R waves in the acute phase of myocardial infarction does not necessarily mean an irreversibly damaged myocardium.

Adult↗
PubMed1984

On-line monitoring of multiple precordial leads in high risk patients with coronary artery disease--a pilot study.

In a pilot study, a computerized precordial mapping system monitored ischaemia on-line in 50 patients (40 with acute myocardial infarction and 10 with unstable angina, class IV (Canadian Cardiovascular Society). All had ST-segment depression or elevation greater than or equal to 0.2 mV in one or more precordial leads when they were admitted to our coronary care unit. After preliminary precordial mapping with 48 electrodes to localize the area of ischemia, 5 to 8 electrodes were placed in and around the centre of the ST-segment changes. The patients were monitored between 24 and 48 h (mean 35.5 h). To minimize problems caused by artifacts, ECG signal quality was improved by the averaging technique. Thereafter, the ECG was evaluated with respect to Q and R wave amplitudes and ST-segment changes. At 3 min intervals, Q and R wave amplitudes and ST segment elevations or depressions, summed for all leads were plotted as a histogram. ECG signal quality was excellent and there were no problems with the attachment of the electrodes. All patients were treated with nitroglycerine intravenously and high doses of heparin and, in several cases, nifedipine as well. Some patients received thrombolytic therapy with streptokinase. Despite therapy, 21 ischaemic attacks were documented in five patients. Seventeen attacks were seen in patients with acute infarction but who were not treated with streptokinase. All attacks were accompanied by chest pain. The duration of ischaemia ranged from 18 to 87 min. Several attacks were stopped immediately by therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina, Unstable↗
PubMed1983

[Diagnostic value of changes in the R-amplitude of the stress ECG compared to the ST-segment depression in patients with significant coronary vessel stenoses].

Exercise electrocardiograms were registered in 50 patients with significant coronary artery stenosis (lumen narrowing greater than or equal to 70%) and in 20 controls without cardiac disease using automated registration (mapping). All patients had a normal ECG at rest and typical angina. ST-segment depression of more than 0.1 mV 60 ms after the J-point in three adjoining leads and in three consecutive registrations could be shown in 46 of the 50 patients (sensitivity 92%) with coronary artery disease, however in no proband of the control group. The sum of the R-amplitudes in the precardiac leads (sigma R) was calculated before and during maximal exercise and six minutes after. Diminution of R-wave amplitudes during exercise was seen in both groups. Six minutes after exercise initial values had been nearly regained. Differentiation of both groups using R-wave amplitudes after exercise thus was impossible. Even using only leads with ST-segment lowering during exercise, a slight increase of R-amplitudes could be measured in only one case. In all other patients R-wave amplitudes diminished also in the ischaemic area with increasing ST-segment depression. RS-inversion was shifted towards the cardiac apex. Thus an increase of R-wave amplitudes indicating coronary arterial disease does not occur in unipolar chest leads in patients with significant coronary artery stenosis and ST-segment lowering during exercise.

Adult↗
PubMed1980

Multi-electrode recording of Hoffman reflexes.

A multi-electrode system has been used to simultaneously record the H-reflex and M response from various locations on the gastrocnemius and soleus. With certain positions of the stimulating electrode in the popliteal fossa, large amplitude M responses were recorded in gastroenemius at a time when only low amplitude H-reflexes were recorded from soleus. These result not only reinforce the importance of casreful selection of the stimulation site but go further and suggest a definite need for the simultaneous monitoring of gastrocnemius and soleus responses to avoid contamination of the soleus H-reflex or its excitability cycle by the unwanted and unsuspected gastrocnemius M response. Conventional practice of recording an H-relfex and its excitability cycle from a single pair of bipolar electrodes located over soleus is susceptible to confounding from the unwanted M response by alterations in the initial mechanical conditions and by the various afferent discharges evoked by a preceding contraction in gastrocnemius.

Animals↗
PubMed1980

QRS mapping in the evaluation of acute anterior myocardial infarction.

In 42 patients with acute anterior myocardial infarction (AMI), we studied the course of Q-wave development and R-wave reduction during the first 48 hours after the onset of chest pain. We used precordial mapping in relation to clinical features, hemodynamic measurements and enzyme release. Q waves developed within 6-14 hours (mean 9 hours) after onset of symptoms. R-wave amplitudes demonstrated nearly a reflected image: They reduced abruptly 5-11 hours (mean 9 hours) after onset of chest pain, coinciding with ST-segment elevation. In 14 patients (group A, 33%) after initial QRS alterations, there were no further changes. Twenty patients (group B, 48%) had a distinct new increase of Q waves (delta sigma Q = 3.0 +/- 2.0 mV/hours) and further R-wave reduction (-delta sigma R = 1.0 +/- 0.6 mV/hour) simultaneous with new severe chest pain and a delayed second increase of enzyme release corresponding with extension of infarction. There were no significant differences between the groups in age, hemodynamics and infarct size calculated from creatine kinase release. Eight patients (group C, 19%) had contradictory findings. Our findings are consistent with previous results indicating that the critical period for intervention is very small except in patients with extension of necrosis.

Adult↗
PubMed1977

[Clinical value of multiple praecordial chest leads for evaluating the course of acute anterior myocardial infarction (author's transl)].

Percordial ST-segment mapping using an improved 48-lead system was evaluated 2-to-3-hourly in 322 single measurements on 24 patients with acute anterior myocardial infarction. Changes in the sum of ST-elevation (capital sigma ST) or in the number of leads with ST-elevation (NST) could be distinguished in two different phases: an initial rapid increase and decrease in capital sigmaST and NST was followed after 6 to 12 hours, by a more plateau-like course, which exhibited, especially in uncomplicated cases, only slight further changes. During the initial phase, marked differences in the maximal rate of decrease were observed for capital sigma ST and NST. In this phase, interpretation of therapeutical interventions using changes of capital sigma ST or NST as reference is therefore very critical. However, during the second plateau-like phase, extension of myocardial necroses is significantly associated with a new steep increase in capital sigma ST. Thus precordial mapping is suitable for rapid and sensitive detection of infarct extension in patients with anterior myocardial infarction. The development of pericarditis or bundle-branch block, which principally can disturb the evaluation of capital sigma ST and NST, occurred only sporadically in a few patients and therefore caused no major problems.

Acute Disease↗
PubMed1977

[Multiple chest leads to evaluate the course of acute myocardial infarction (author's transl)].

At present, precordial mapping is the only reliable method to define the course of myocardial ischemia in patients with acute myocardial infarction. To improve registration technique and evaluation an elastic synthetic plate with 48 electrodes and a computer program for calculation of the different ecg-changes have been developed. Registration and evaluation require an average period of 15 minutes (+/-3 minutes) thus allowing repeated application within time intervals.

Acute Disease↗