High-resolution electrocardiography in acute myocardial infarct

The author starts by highlighting the importance of risk stratification in patients who have survived a myocardial infarction. High resolution electrocardiography, also called signal-averaged electrocardiography (SAECG), appears in this setting as a diagnostic tool that, by providing important information about the way the intraventricular conduction of the electrical impulse is made, contributes to the characterization of the arrhythmogenic substrate, which is the basis of ventricular tachycardia and fibrillation. By resorting to the averaging of the electrocardiographic signal, SAECG enables us to detect ventricular late potentials whenever the analysis of that signal is made in time-domain. Further details, which will enrich the information on ventricular activation, can be obtained if the analysis is made in the frequency-domain (spectral analysis). The importance of detecting abnormalities in the SAECG recordings lies in the fact that those abnormalities are related to the occurrence of ventricular tachycardia and fibrillation, which are responsible for arrhythmic death. After referring to the criteria of positivity of SAECG and its reproducibility, the author approaches the most important part of the paper: the clinical applications of SAECG. After focusing on the interest of the method in noncoronary conditions, its usefulness in patients with acute myocardial infarction is pointed out. The author then mentions the prevalence of abnormalities in SAECG in patients with acute myocardial infarction and emphasizes the interest of the method in risk stratification. The author then presents the results of his Group in what concerns prevalence and prognosis. Finally, the author refers to the application of SAECG in other forms of coronary artery disease besides myocardial infarction.     

Nutritional problems in acute myocardial infarct

Hypocaloric nutrition in patients during the first days of myocardial infarction cannot be suggested any longer. Because of several reasons the minimum calory uptake should be about 2000 kcal/per day. Patients with enddiastolic pulmonary artery pressures above 20 mm Hg which is especially a high risk group should be treated parenterally with solutions of carbohydrates, insulin, and potassium. This regimen appears to be of a special importance at beginning shock or during cardiogenic shock.     

Dopexamine attenuates endotoxin-induced microcirculatory changes in rat mesentery: role of beta2 adrenoceptors

OBJECTIVE: To investigate the influence of dopexamine on endotoxin-induced leukocyte adherence and on vascular permeability in postcapillary venules of rat mesentery. DESIGN: Randomized, controlled trial. SETTING: Experimental laboratory. SUBJECTS: Twenty-seven male Wistar rats, weighing 250 to 350 g. INTERVENTIONS: Rats received one of three treatments: a) infusion of Escherichia coli endotoxin without dopexamine pretreatment; b) infusion of endotoxin with dopexamine pretreatment; or c) infusion of endotoxin after pretreatment with dopexamine and ICI 118,551, a selective beta2-receptor antagonist. MEASUREMENTS AND MAIN RESULTS: Leukocyte adherence, red blood cell velocity, and vessel diameters in postcapillary venules were evaluated using in vivo videomicroscopy. Vascular permeability was determined by measuring the extravasation of fluorescence-labeled albumin. Venular wall shear rate was calculated from red cell velocity and vessel diameter. Dopexamine attenuated both the increase in leukocyte adherence and vascular permeability during endotoxemia. The attenuating effect on leukocyte adherence could not be antagonized by the beta2-adrenoceptor antagonist. However, the attenuating effect on vascular permeability was antagonized by ICI 118,551. Dopexamine prevented a decrease in venular wall shear rate during endotoxemia. This effect was not influenced by ICI 118,551. CONCLUSIONS: Dopexamine attenuates endotoxin-induced microcirculatory disturbances in rat mesentery. The attenuating effect on vascular permeability is a beta2-adrenoceptor-mediated process, whereas the beta2-adrenoceptor actions of dopexamine play no significant role in attenuating leukocyte adherence.     

Angina in the acute phase of myocardial infarct

Factor VIII (AHG) activity was assayed in the plasma specimens from 1016 regular and controlled blood donors. Age and ABO blood groups had highly significant effects on factor VIII concentrations, whereas the effect of sex was not significant. The median in the donors of blood group O rose from 87% at the age of 20 to 119% at the age of 60 years, and the median in blood groups A and B+AB of corresponding ages rose from 108 to 147%. An interaction effect of age and blood groups was present only at the 5% level of significance. The present data and the previous findings of others suggest the existence of an association between high factor VIII levels and thrombotic states.     

Biochemical markers in acute myocardial infarct

Exact and early diagnosis of acute myocardial infarction is essential for the subsequent routine management of this frequent cardiovascular disease. At present, the clinical biochemistry possesses a set of more or less cardiospecific protein markers for early detection of myocardial ischemic damage. After the admission of patient to the hospital, serial estimations of rather non-specific enzyme activities (creatine kinase, its MB-izoenzyme, lactate dehydrogenase, hydroxybutyrate dehydrogenase) are currently used for the detection of acute myocardial infarction and for the further monitoring of the patient and managing his therapy. In the past decade, many cardiospecific biochemical markers were discovered and gradually introduced into the routine clinical practice. The most perspective markers are some molecules of contractile proteins of heart myofibrils (troponins, myosin chains) as well as "rediscovered" myoglobin. The aim of this review article is to inform about the commonly used, as well as about the new biochemical markers, to discuss some problems of diagnostic strategy in the early and exact detection of ischemic myocardial damage and to attract attention to the difficulties. However its disadvantage resides in its presence in both myocardium and skeletal muscles which arise when the diagnosis of acute myocardial infarction is prematurely excluded from consideration and such patients are discharged too soon from hospital. (Fig. 1, Tab. 1, Ref. 72.)     

The apexcardiogram in acute myocardial infarct

The relation between intracardial haemodynamics and apicocardiogram (ACG) parameters is explained. A wave (amplitude and duration), A/H ratio, true and total TCI, total systole, total expulsion, RIV, RFW, TE/TCI (total) and TE/TCI (true) findings in 22 patients with acute myocardial infarct are presented. Attention is also given to clinical and radiological signs of cardiac insufficiency and the infarct site. Constant and significant increases in the A wave, A/H ratio and RIV, together with a decrease in total expulsion, were noted, particularly in cases with clinical evident insufficiency. In the pre-expulsive stage, ACG Data could not be taken as a reliable index of myocardial contractility in cases where insufficiency was not manifest. It is felt, therefore, that ACG may be of assistance in the evaluation of changes in myocardial performance, even where clinical and radiological signs of decompensation are absent.     

Treatment acute myocardial infarct in the pre-hospital phase

OBJECTIVE: To examine the circadian variation in the signal averaged electrocardiogram (saECG) and heart rate variability and investigate their relations in healthy subjects. METHODS: 24 hour ECGs were obtained with a three channel recorder using bipolar X, Y, and Z leads in 20 healthy subjects. The following variables were determined hourly: heart rate, filtered QRS (f-QRS) duration, low and high frequency components of heart rate variability (LF and HF), and the LF/HF ratio. RESULTS: Heart rate, f-QRS duration, HF, and the LF/HF ratio showed significant circadian rhythms, as determined by the single cosinor method. Heart rate and the LF/HF ratio increased during daytime, and f-QRS duration and HF increased at night. f-QRS duration was negatively correlated with heart rate (r = 0.95, p < 0.001) and the LF/HF ratio (r = 0.94, p < 0.001) and positively with HF (r = 0.93, p < 0.001). CONCLUSIONS: f-QRS duration has a significant circadian rhythm in healthy subjects and is closely related to the circadian rhythm of autonomic tone.     

The pre-hospitalization period in acute myocardial infarct

The article reviews the possibilities of biochemical markers in coincidence with the assessment of prognosis in acute coronary syndromes and in the revealing of effectivity of their therapy. The current options of clinical biochemistry in many cases allow to supplement, confirm, or exclude the results of modern physical and other clinical examination methods and in this way to contribute to the accuracy of the diagnostic process, and enable to comment the prognosis and the risk measure of the patient. A significant progress has been achieved in the assessment of effectivity in thrombolytic therapy in acute myocardial infarction, where especially the series assessment of myoglobin levels or specific troponin cardiomarkers can facilitate the process of physician's decision as to the assessment of the subsequent procedure in the treatment of patients. The assessment of levels of both specific and partly less specific cardiomarkers becomes one of the criteria of the decision in coincidence with ischaemic episodes in the peri and postoperative periods (the diagnosis of peri-operative myocardial infarction). Specific troponin cardiomarkers acquire an extraordinary significance in the prediction of the measure of risk in patients with unstable angina pectoris where already one single assessment of the level of these markers is sufficient for hospitalization of the patient and thus enables to change the physician's strategy of further therapy. (Ref. 95.).     

Electron-microscopic study of changes in the myocyte ultrastructure under the effect of hyaluronidase in experimental myocardial infarct]

The myocardium of 60 rabbits with experimental myocardial infarction induced by ligation of the anterior interventricular branch of the left coronary artery was studied by electron microscopy. The main group of animals received hyaluronidase. The size of the infarct was judged by the ECG recorded with 15 precordial leads. Normalization of myocytes in the non-ischemic zone of the left ventricle in the treated animals revealed. Better intactness of myocytes in the peri-infarction and non-ischemic zones was noted, which may apparently accelerate ECG dynamics, change the total balance of necrotic material in the direction of its decrease, and, consequently, influence the indices of blood plasma creatine phosphokinase.     

Clinical prediction of the early prognosis in acute myocardial infarct

Several clinical factors can influence the pathophysiology, clinical course and prognosis of acute myocardial by different means. Some of them may be easily detected through the history, physical examination or ECG in an early phase. The knowledge of these factors may help the therapeutic decision making of patients with myocardial infarction. The influence for the main clinical factors (age, sex, risk factors, cardiologic antecedents and evolutive findings) on the short-term prognosis of acute myocardial infarction is reviewed. An analysis of the likely mechanisms of the influence of these factors on infarct prognosis is also performed.     

Adjuvant therapy in patients with acute myocardial infarct

Besides the thrombolytic therapy several adjuvant therapeutic measures were identified which significantly improve the prognosis of patients with acute myocardial infarction (AMI). These measures include the treatment by means of acetylsalicylic acid (ASA), beta-blockers and ACE inhibitors. Early administration of ASA and beta-blockers are indicated in all patients with AMI who have no contraindications for this therapy. They are especially the patients with manifest heart failure or asymptomatic left ventricular dysfunction who benefit from ACE inhibitors. The effectivity of routine administration of other medicaments such as anticoagulants, nitrates, calcium channel blockers and magnesium, have not been convincingly proved. However, some selected patients with AMI can benefit from these medicaments. Intravenous administration of heparin is unambiguously justified only in thrombolysis with t-PA. Thrombolyses with streptokinase, urokinase, and anistreplase are justified only at high risk of thromboembolic complications. Their prevention and therapy include also the necessity to restrict the administration of pelentan. The use of nitrates is indicated in patients with AMI in case of sustaining stenocardia, arterial hypertension and manifest heart left ventricular failure. Until the definitive standpoint is gained regarding the effect of magnesium in patients with AIM, its administration remains especially indicated in cases of arterial hypertension, tachycardiac disturbances of the heart rhythm and states of assumed or proved hypomagnesiemia. In AMI cases when magnesium is used in order to protect the patient from reperfusion lesion, it must be administered prior to the reperfusion therapy. An intensive research in the field of therapeutical measures in patients with AMI still continues. It is certain that it will soon bring further knowledge which will in turn improve the prognosis and quality of life of patients with AMI. (Tab. 4, Ref. 133.)     

The cellular substrates of the acute myocardial infarct syndrome

Immunoassay techniques yield estimates of concentrations of analytes based on comparison to known concentrations of a reference solution. The use of the nonlinear logistic model makes the error estimates and confidence levels approximate. When the goal of such a study is estimation of several unknowns, methods in common usage do not account for 'simultaneous' inference, i.e. the repeated use of the standard curve for estimating several concentrations. Alternative methods are described which take multiple use of the reference curve into account. Simulations using normally distributed data with variance proportional to a power of the mean compare different methods of obtaining calibration intervals and illustrate the approximate nature of all such techniques. Calibration intervals based on simple, commonly used methods do not provide the coverage promised, even for one-at-a-time estimation, and are not suited for multiple estimation and comparison.     

The microcirculatory bed of the human epididymis

Based on the material of 24 human epididymides at ages 18 to 54, hemomicrocirculatory bed was studied of epididymis in man with the aid of a complex of morphologic techniques (injection of 20% Chinese ink-gelatine suspension, injection of a weak solution of caustic silver, transmission electron microscopy). It has been ascertained that architectonics and ultrastructural features of various links of the hemomicrocirculatory bed have signs of regional specificity for the subcapsular vascular network, small seminal ducts of caput epididymidis, ductus epididymidis of the head, body and tail of the organ. Reasons are discussed why specific hemomicrocirculatory bed should be caused to develop in different parts of the organ.     

Parameters of thyroid gland function in acute myocardial infarct

In 31 patients with acute myocardial infarction triiodothyronine (T3), free triiodothyronine (FT3), thyroxine (T4), free thyroxine (FT4), thyrotropin (TSH) and TBG were measured and T3-test was performed on the 1st and the 10th day of hospitalization. The 1st day values for T3, FT3 and TBG were significantly lower, and T4 and TSH were significantly higher than in the control group. The same differences were noted on the 10th day for T3, FT3 i T4. TBG was significantly higher than the 1st day. TSH was lower and it was not significantly different from control values. These results are compatible with clinical observations described in severe nonthyroidal illnesses.