Biomedical subjects
Publications and source records attributed to S Janousek.
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Streptokinase was discovered in 1933. Its importance has gradually grown since 1950's of the last century when it was used as the utterly first thrombolytic agent. Since the discovery that majority of acute myocardial infarctions is caused by thrombus in the area of ruptured endothel above the atherosclerotic platelet, it has become the first remedy able of real causal treatment of acute myocardial infarction (AMI). These days it becomes an obsolete remedy because of a range of disadvantages. Neutralizing antibodies for instance remain in organism for many years after its administration, which results in an inefficacious treatment. Moreover it causes allergic reactions or anaphylaxis in a part of population, hypotension, and decrease of its fibrinolytic effect after more then 3 hours after development of AMI. The most problematic is its anticoagulant effect lasting more than 24 hours after its administration and simultaneous increase in prothrombotic activity, which is a disadvantage if intervention treatment methods are appropriate (direct coronary angioplasty). The only advantage of streptokinase is its relatively low price. However, it cannot justify its use as a thrombolytic agent of the first choice and it is high time for it to be replaced in its treatment indications by plasminogen activator or by thrombolytic agents of the third generation derived from it, which can be conveniently administered in the bolus form.
The effect of repeated exposure to carbon monoxide (CO) on the response of middle-age rats to an acute CO exposure combined with a low dose of a sympathomimetic agent was studied. A group of 12 rats (male albino, Wistar, age 9 months) without ECG abnormalities was divided into two subgroups matched for weight, heart rate and ECG: one subgroup was exposed to 500 ppm CO for 6 h/d, 5 d/w, for 6 weeks (peak COHb 31.5%, SD 3.5); the other one (controls) was exposed to fresh air. Two or three days after the last exposure both groups underwent combined challenge with 0.025 mg/kg isoproterenol s.c. and 90 minute exposure to CO in a concentration increasing from 500 to 1500 ppm; ECG was recorded continuously. The hearts were examined morphometrically and histologically. The CO-preexposed subgroup had, as compared to controls: 1) significantly higher blood hemoglobin (by 25%), erythrocyte count (by 28%) and volume (by 6%), and hematocrit (by 33%); 2) the same peak COHb; 3) lower basic heart rate and an earlier decrease after isoproterenol, 4) significantly smaller increase in ECG abnormalities and arrhythmias after isoproterenol and during CO exposure; 5) nonsignificantly higher heart weight indexes; 6) a nonsignificantly lower score of histological abnormalities. The global score of ECG pathology during CO exposure (abnormal pattern or arrhythmia) correlated best (multiple corr. coef. >0.9) with end-exposure free (non CO bound) hemoglobin (negatively) and with mean heart rate during exposure (positively): the lower score in the preexposed subgroup was attributable primarily to the increased hemoglobin. Six-week intermittent CO exposure induced marked compensatory processes (hematological) but only a tendency to adaptational changes in the heart (by gross morphometry), and decreased the ECG response to CO+ isoproterenol challenge at the same COHb.
In 76 patients (66 men and 10 women, age 20-71 years) with stable angina pectoris planar thallium myocardial perfusion scintigraphy, bicycle ergometry and coronary angiography were performed. Thallium scintigraphy was highly sensitive (97%) for detection of ischaemic heart disease, the sensitivity of ergometry was 75%. When comparing patients with affected 1, 2 and 3 coronary arteries perfusion scintigraphy had a sensitivity of 100%, 90% and 100% resp., while bicycle ergometry 62%, 90% and 82% resp. The specificity of perfusion scintigraphy was low (47%), compared with ergometry (60%). The finding of s reversible perfusion defect during scintigraphy indicated significant affection of coronary arteries. The scintigraphic finding of diffuse myocardial ischaemic affection was not significant for assessment of the severity of the coronary artery disease.
The determination of erythrocyte zinc protoporphyrin (ZZP) was implemented as an indirect method for assessing lead levels in the blood in the follow-up of Czech children regarding the lead load due to automobile traffic. Simultaneously, basic indicators of the red blood picture were studied. A screening study was conducted with 2668 school-age children residing permanently in three different regions of our country. The differences in basic hematological indicators, i.e. number of erythrocytes, hemoglobin content, hematocrit and red blood cell volume, like the differences in zinc protoporphyrin in the peripheral blood, did not confirm the initial hypothesis on the relatively greater load of the Czech child population due to lead from exhaust fumes of combustion motors. Also, no regional differences were observed. The differences found in the abovementioned indicators reflect the influence of an overall environmental pollution rather than that of a toxic effect of lead.
Recently in various departments interest in dobutamine stress echocardiography is increasing. Originally this examination was meant for the diagnosis of suspected ischaemic heart disease in patients unable to tolerate a physical load. Clinical applications of this test are constantly expanding and comprise a number of risk patients. The purpose of the submitted paper is to discuss the safety of dobutamine stress echocardiography. The authors submit an analysis of 259 examinations of patients with suspected ischaemic heart disease (46%), after acute myocardial infection (42%) and patients with significant left ventricular dysfunction (12%). 231 examinations (89%) were made up to the defined maximum. The test was terminated prematurely in 12 patients on account of arrhythmia, in 10 because the test was positive, in two because of extracardiac effects, in three instances on account of hypotension and in one patient on account of pressure hyperreaction. Arrhythmias were recorded in 26%, discontinuous ventricular tachycardia was recorded only in two patients (0.7) with severe left ventricular dysfunction. Hypotension was found in 13%, pressure hyperreaction in 2%. Palpitations were noted in 15% of the examined patients and extracardiac side-effects in 31%. None of the side-effects called for therapeutic intervention. The authors consider dobutamine stress echocardiography a safe test which is well tolerated by the majority of patients and there is a minimum of side-effects. A higher risk must be foreseen in patients with reduced left ventricular function, hypertrophy of the left ventricle and those with an history of arrhythmias.
The objective of the present work was to evaluate dobutamine echocardiography in patients after myocardial infarction. The group of patients comprises 39 subjects, age 54 +/- 10 years with a first non-complicated myocardial infarction treated by thrombolysis. The patients were examined on the 5th-7th day with small amounts of dobutamine (5 and 10 micrograms/kg/min.) and a maximal test after two weeks and three months after the myocardial infarction. During the week after the first maximal test coronarography was made in 33 patients. During the first examination at rest the authors observed asynergy in 237 of 780 segments. Low dobutamine doses revealed the presence of a viable myocardium in 87 segments (36%). The sensitivity, specificity, positive predictive value and negative predictive value were 72%, 77%, 55% and 88%. In eleven patients several arteries were affected, the sensitivity of dobutamine echocardiography for prediction of affection of several vessels was 70% and the specificity 95%. During examinations after three months in some of the patients the kinetics improved, in particular in patients after revascularization operations and in patients who were subjected to a rehabilitation programme. The authors conclude that dobutamine echocardiography is a safe loading method with a minimum of side-effects even in patients in early stages of myocardial infarction. The use of low dobutamine doses is a new promising method for assessment of reversible but also irreversible myocardial dysfunction. The maximal test will help to detect patients with affections of several vessels and help to differentiate patients with a greater risk and necessity of more aggressive treatment.
The authors examined the concentration of erythrocyte zinc-protoporphyrin (ZPP) by a haematofluorometric method in 175 women during delivery and the levels in their children. They assessed basic haematological indicators, the number of red cells, their volume, number of reticulocytes, haemoglobin concentration, haematocrit and sideraemia. All were average values within the physiological range in both examined groups. Statistical evaluation revealed a significant difference between mean values of sideraemia in mothers and children and mean values of the erythrocyte ZPP in both groups. The authors found also a medium significant correlation between ZPP and the erythrocyte volume and the erythrocyte volume and sideraemia. The correlation of different indicators was more marked after classification of the examined women and neonates into subgroups by haemoglobin concentrations and ZPP. In the subgroup of mothers with Hb values lower than 115 g/l a positive correlation was found with the number of reticulocytes red cell volume and sideraemia. In the subgroup of anaemic women (Hb concentration lower than 105 g/l) a negative correlation with the foetal sideraemia was found.
The authors assessed in 24 men with stable angina pectoris, using means of ergometry, the antiischaemic and antianginose effects of a combination of the nitrate Iso-Mack retard and the diuretic Moduretic. The effects were compared with the effects of Iso-Mack retard administered alone and with the effects of placebo. The examination was made after a single dose of the drugs and after three-week administration. The authors revealed that a single dose of the diuretic significantly enhanced the effects of nitrate. During long-term administration the diuretic did not prevent a significant diminution of the nitrate effects. Finally the authors discuss possible mechanisms of development of tolerance for nitrates and possibilities how to influence this tolerance by a diuretic.
Transdermal nitroglycerin patches are used mainly in the therapy of angina pectoris. However, the magnitude and duration of their effects are still controversial. In this study, transdermal discs with nitroglycerin were given to 14 patients with acute myocardial infarction (AMI) and mild hemodynamic impairment. Seven patients received Nitroderm TTS, and seven patients Deponit 5 (in this case 2 patches), the nitroglycerin dose being 10 mg. Hemodynamic measurements were made 19-24 h after application of the patch and 1 h after its removal. Comparing with the values obtained 1 h after removal of the patch, 19-24 h after the application of the patch heart rate was significantly higher (90.2 +/- 3.8 vs. 85.6 +/- 4.0 min-1; p less than 0.01), mean right atrial pressure was significantly lower (10.8 +/- 1.0 vs. 12.7 +/- 1.3 mm Hg; p less than 0.01), and so were the pulmonary artery pressure: systolic (36.9 +/- 3.0 vs. 43.0 +/- 3.1 mm Hg; p less than 0.001), mean (26.8 +/- 2.1 vs. 31.4 +/- 2.0 mm Hg; p less than 0.001) and the capillary wedge pressure (19.2 +/- 1.8 vs. 23.0 +/- 1.9 mm Hg; p less than 0.01). These findings revealed that in patients with AMI hemodynamic effects persist for at least 19 h after single application of a nitroglycerin patch of 10 mg. The therapy is safe and the risk of side effects is small.
In 314 patients with a first myocardial infarction, admitted within four hours after development of symptoms, the authors used in addition to standard therapy heparin treatment in 205 and streptokinase treatment (1.5 mil. u. i.v. with subsequent i.v. heparin administration) in 109 patients. Thrombolytic treatment was more effective, it reduced the lethality by 55.7% and was associated with a lower incidence of complications during the first 30 days. The reduced lethality, however, did not reach statistical significance because of the small number of patients and the low mortality rate in both groups. The left ventricular ejection fraction was practically equal in both groups after six weeks. Undesirable effects of thrombolytic therapy were rare and did not seriously threaten the patients. Provided contraindications are carefully respected, this treatment is safe and its routine use in the treatment of new myocardial infarctions must be supported. Streptokinase remains the drug of choice because it is equally effective as other available fibrinolytics and is the cheapest one.
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Using two-dimensional echocardiography, the authors made a one-year investigation of left ventricular function in a group of patients after a first transmural myocardial infarction. They evaluated subjectively and quantitatively changes in the contractility and the development of the diastolic area of the left ventricle. They revealed a certain improvement of the contractility, probably as a result of the development of a collateral circulation and altered structure of the infarction focus associated with dilatation of the left ventricle by the Frank-Starling mechanism.
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In 90 subjects, mean age 52 +/- 9 years with a first acute myocardial infarction (AIM) the authors evaluated the QRS score by Wagner's method. The assembled values were compared by linear regression with values of the ejection fraction (EF) of the left ventricle (LV), calculated according to Dodge's method from left-sided ventriculography made during the same period (on average 45 +/- 9 days after the development of AIM). For the entire group a correlation r = -0.43 (p less than 0.001) was obtained, for the sub-group of patients with AIM of the anterior wall (n = 44), r = -0.57 (p less than 0.001), correlation was found in patients with AIM of the lower wall (n = 27), r = -0.11 (p greater than 0.1). For the sub-group of patients of the whole group under the age of 60 years incl. (n = 60) the correlation was r = -0.52 (p less than 0.001), in patients above 60 years (n = 22) no correlation was found (r = -0.21, p greater than 0.1) between the QRS score and the EF of the LV. Calculation of the QRS score is a conventient auxiliary method for assessment of the affection in AIM of the anterior wall and in patients under 60 years of age.
The authors examined by echocardiography at rest and after exertion a group of 55 patients after a clinically confirmed first transmural infarction. They compared the echocardiographic findings with coronarographic ones. The finding at rest, as regards impaired mobility of the left ventricular wall, corresponded to the clinical finding and the coronarographic finding. By diagnosis of the extended asynergy of contraction during an isometric load it was not possible to differentiate the functional and organic cause of impaired mobility and thus to assess the extent of the coronary affection. The impaired mobility of the left ventricular wall is associated above all with the state of the blood supply rather than with the finding on the coronary artery.