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Biomedical subjects

A P Ivanov

Publications and source records attributed to A P Ivanov.

At least 19 recordsLinked to original sources
PubMed2006

[Left ventricular remodeling in patients with arterial hypertension].

The subjects of the study were 85 patients with arterial hypertension alone or in combination with coronary heart disease with stable stenocardia attacks and postinfarction cardiosclerosis. The purpose of the study was to evaluate the peculiarities of left ventricular (LV) remodeling in such patients. The study demonstrated peculiarities of the structural and geometric indices in men and women, as well as their connection with the process progression within the framework of the cardiovascular continuum. The authors offer an original scheme of the dynamics of cardiovascular system condition in connection with exposure to risk factors and the forming of concentric or eccentric LV hypertrophy. The studies of structural changes included in the scheme may serve as a study model of the most important mechanisms responsible for progression or regression of the pathological changes in the LV at particular stages of the disease.

Adult↗
PubMed2005

Poliovirus-binding inhibition ELISA for evaluation of immune response to oral poliovirus vaccine: a possible alternative to the neutralization test.

This study describes an ELISA variant (Binding Inhibition ELISA, BI ELISA) for the quantitative determination of neutralization-relevant antibodies to polioviruses. The test differs from previously described analogs by utilizing polyclonal immune reagents: capture antibodies and biotin-labeled detecting antibodies. The BI ELISA was compared with the conventional neutralization test (NT) by testing live Sabin and wild-type poliovirus strains. The comparison of 68 serum samples taken from Oral Poliovirus Vaccine (OPV) recipients showed 100% specificity and sensitivity for Sabin 1 and Sabin 2, and 100% sensitivity and 97% specificity for Sabin 3. Good correlations (r = 0.7, 0.77, 0.65 for Sabin 1, 2, 3, respectively) were demonstrated between the NT and BI ELISA results. These results indicate that the BI ELISA can be used as a reliable alternative to the NT for determination of neutralization-relevant antibodies to polioviruses in vaccinees and in large-scale sero-epidemiological studies.

Animals↗
PubMed2004

[Clinical and instrumental evaluation of the myocardial reserve in patients with prior myocardial infarction].

The clinical manifestations of heart failure (HF), myocardial systolic and diastolic functions and the indices of remodeling of the left ventricle (L V) were compared to define the most informative characteristics of the myocardial reserve (MR) in patients with prior myocardial infarction (MI). Examination of 220 patients with MI indicated that the low LV ejection fraction reliably determined only a high functional class (FC) of HF. Myocardial diastolic dysfunction (DD) was equally characteristic of any FCs of HF and the restrictive type of blood filling was most commonly associated with FC III-IV of HF. LV concentric hypertrophy, as well as DD, occurred in all FCs of HF. The detection rate of LV eccentric remodeling significantly increased from 5.1% in FC I to 98.7% in FC IV, which characterized this process as the most characteristic while grading the decrease in MR in patients with MI.

Adult↗
PubMed2003

[Assessment of coronary reserve in patients after myocardial infarction].

Clinical data were compared with results of stress tests (veloergometry and transesophageal cardiac pacing) in 320 patients 1.5-2 months after myocardial infarction. Severity of angina was classified as functional class 0, I, II, III and IV in 78 (24.4%), 162 (50.6%), 64 (20%), 12 (3.75%), and 4 (1.25%) patients, respectively. Characteristics of coronary reserve by exercise test and transesophageal pacing considerably differed mostly in patients with class 0 and I and were practically identical in patients with class III and IV angina. Pearson's coefficient of correlation was the highest between clinical data and results of transesophageal pacing. It was lower between results of pacing and veloergometry and the lowest between clinical data and results of veloergometry. Values of Pearson's coefficient of correlation rose with increase of functional class of angina from 0.38 to 0.88. All methods analyzed in this study were reliable for estimation of degree of lowering of coronary reserve in patients with high functional class of angina. However in patients without angina or with class I angina additional methods were required and transesophageal cardiac pacing appeared to be a preferable technique for assessment of level of coronary reserve in these patients.

Adult↗
PubMed2003

[Autonomic balance and some daily ECG monitoring parameters in patients with prior myocardial infarction].

The specific features of ischemic and arrhythmic manifestations and their relationship to the autonomic nervous system studied by analysis heart rhythm variability (CRV) were investigated in 87 patients with prior large myocardial infarction by using Holter monitoring. Spectral analysis of CRV revealed that in painful ischemia (PI) the total frequency (TF) of waves significantly decreased by 22%. In turn, episodes of silent ischemia (SI) were associated with a substantial (42%) increase in VLF-range power with a simultaneous significant reduction in the HF region of the spectrum by 53.8%. At the same time, the PI and SI groups greatly differed in the severity of complicated ventricular arrhythmias registered in 66.7 and 24.4% cases, respectively (p < 0.01). Thus, differences have been found in the episodes of myocardial ischemia: the pain equivalents are characterized by a higher risk for arrhythmia and SI is likely to be associated with the imbalance of ANS and with higher neurohumoral activity.

Adult↗
PubMed2003

[The phenomenon of intermittent myocardial ischemia and characteristics of myocardial reserve in patients with myocardial infarction].

AIM: To study coronary and myocardial reserves in myocardial infarction survivors (MIS) with consideration of development of intermittent ischemia during transesophageal pacing (TEP). MATERIAL AND METHODS: 320 MIS were examined 1.5-2 months after myocardial infarction onset. 30 healthy male volunteers served control. Stepwise overdrive TEP was made in all the examinees with parallel estimation of central hemodynamics by tetrapolar chest rheography with assessment of systolic and diastolic parameters. RESULTS: In the course of TEP, 39.4% MIS developed intermittent ischemia (II) at frequencies 120-140 imp/min. II presented as a significantly depressed ST segment on ECG. There was a simultaneous lengthening (1.4-fold) of diastole and a fall (1.5-fold) of end-diastolic pressure in the left ventricle (EDP). At frequencies 140-160 imp/min the length of the diastole shortened while EDP rose. CONCLUSION: The II phenomenon demonstrates a key role of coronary reserve. Changes in coronary and myocardial reserves during TEP in II development are interrelated. They may represent unknown adaptive mechanisms of the myocardium protecting against unfavourable outcomes of ischemic episodes.

Blood Pressure↗
PubMed2002

[Diagnostic and prognostic aspects of angina pectoris preceding myocardial infarction in long-term follow-up].

AIM: To trace relations of premyocardial infarction (preMI) angina, myocardial reserves and clinical peculiarities within a year of outpatient follow-up. MATERIAL AND METHODS: Coronary and myocardial reserves were studied in 320 MI survivors using veloergometry, transesophageal pacing (TEP), 24-h ECG monitoring, echocardiography. Cardiac output reaction to TEP was assessed. RESULTS: Patients with preMI attacks of stable angina had coronary reserve 47.9% less than they had before MI while cardiac failure by NYHA criteria aggravated by 33.3%. Myocardial ischemia at bicycle exercise in these patients developed much later and its threshold rose by 34.2%. The degree of cardiac ejection fall in TEP in patients without angina before MI was 2.4 times greater than in patients without history of IHD. There were specific features of diastolic relaxation of the myocardium and variability of cardiac rhythm in the compared groups though the groups did not differ significantly by arrhythmia events and morphological characteristics of the scar zone. Survival showed a tendency to lowering of lethal outcome risk in the compared groups followed up since the observation month 6 without significant differences depending on the presence of preMI angina. CONCLUSION: PreMI angina contributes to formation of coronary and myocardial reserves which are better to assess at TEP and with analysis of hemodynamic reaction to induced rise in heart rate.

Adult↗
PubMed2001

[Processes of left atrial remodeling in myocardial infarction survivors as shown by esophageal rheography].

To study the condition of the left atrium (LA) in patients with myocardial infarction (MI), 112 MI patients were compared to 24 healthy controls by the data obtained at ultrasonic investigation of the heart and esophageal rheography. 73.2% of the patients early after MI showed dilated LA. There were also changes in the ascending part of the rheographic atrial wave at its registration from the esophagus. Its marked prolongation (> 40% of the duration of the whole LA systole) is associated with alterations in the myocardial wall tonicity. If the above value was less, the number of supraventricular extrasystoles significantly increased, episodes of cardiac fibrillation occurred. Changed tonicity of the LA wall was accompanied also with prominent prolongation of the electrophysiological parameters of transesophageal pacing characterizing pacemaker's function and atrioventricular conduction. This suggests involvement not only left but also right atrium. Conclusion is that LA tonicity in MI is damaged and can be studied with esophageal rheography.

Adult↗
PubMed2001

[Autonomic nervous system balance, variability and arrhythmia in survivors of myocardial infarction].

AIM: To investigate relations between heart rhythm variability (HRV), vegetative balance and electric myocardial activity in myocardial infarction (MI) survivors. MATERIAL AND METHODS: HRV was studied by short 5-min parts of ECG and data of ECG Holter monitoring were analysed for 98 patients who had macrofocal MI 1.5 months to 5 years before. RESULTS: Manifestations of electric heart instability were polymorphic. 69.4% examinees had hyperactivity of the parasympathetic nervous system (PSNS). The influence of the sympathetic nervous system (SNS) increased with growing severity of arrhythmia. Supraventricular arrhythmia occurred more frequently in high PSNS activity, while ventricular arrhythmia occurred more often in SNS prevalence combined with low HRV. CONCLUSION: HRV analysis for MI survivors, especially in combination with Holter ECG monitoring, gives an objective assessment of various manifestations of cardiac dysfunction and therefore enables timely adequate therapy.

Adult↗
PubMed2000

Features in coherent transmittance of a monolayer of particles.

Coherent and incoherent transmittance values of a monolayer of particles are considered. Such a monolayer is a set of particles whose centers are located in the same plane. We set forth the conditions for the effect of coherent-transmittance quenching, which takes place as a result of the interference between incident and forward-scattered waves. Using the single-scattering approximation we determined size parameters and particle refractive indexes for this interference effect in the case of identical isotropic spherical particles. The influence of polydispersity and the fine structure of light-scattering characteristics on the quenching effect has been estimated. It is shown that the polydispersity destroys this interference effect only at large widths of particle-size distribution functions. The influence of multiple scattering on this effect is considered in the quasi-crystalline approximation. Multiple scattering results in increasing size parameters and decreasing particle concentration at which coherent transmittance quenching takes place in comparison with the case of single scattering. Our theoretical results for suspensions of latex particles in water are in fairly good agreement with the experimental results.

Journal Article↗
PubMed2000

[Variants of hemodynamic response in transesophageal pacing in patients with chronic circulatory insufficiency].

Compared were hemodynamic responses to transesophageal pacing (TEP) in 86 patients with symptoms of chronic circulatory insufficiency (CCI) and 46 healthy individuals. Cardiac output was assessed by tetrapolar chest rheogram under stimulation and its discontinuation, and end diastolic pressure (EDP) in the left ventricle. Stroke volume was diminished in all the examinees. Cardiac output changed in different directions. Poststimulation recovery of cardiac output was different. Contribution of ejection period is discussed the prolongation of which indirectly indicates shorter time of diastole and, respectively, diastolic filling of cardiac chambers. EDP rose both in healthy controls and patients, being higher in the patients. The role of systolic and diastolic compensatory mechanisms in CCI development is considered.

Adult↗
PubMed2000

[Bicycle exercise test, Holter ECG monitoring and hyperventilation test in diagnosis coronary arteries stenosis in postmyocardial infarction patients].

To assess contribution of dynamic (vasospastic) stenosis to pathogenesis of anginal attacks in postmyocardial patients, 148 patients 15-4 months after the infarction were examined using bicycle exercise, Holter ECG monitoring and hyperventilation test (HVT). The relations between painless myocardial ischemia and vasospastic reactions in the course of hyperventilation were also studied. The ECG segment ST responded similarly in 97% of the patients. In positive HVT there was a slight rise in the heart rate and double product. Vasospastic reactions prevailed in the disease aggravation. Dynamic stenosis in postmyocardial patients is characterized by significant variability of ischemia threshold and total duration of ischemic episodes more than 30 minutes for 24 hours.

Adult↗
PubMed1997

[Reconstructive plastic surgery of the esophagus in children].

The article presents the authors' experiences with reconstructive-plastic operations of the esophagus in children. The esophagoplasty was performed in 60 patients with congenital and acquired diseases. Among the congenital diseases are esophageal atresia, short esophagus and Barrett's esophagus, the acquired diseases include postburn scarry injuries. The optimum method of creation of the artificial esophagus are described. Of great significance are thought to be angiosurgical and microsurgical methods of cutting out the intestinal transplants. Cases of free autotransplantation of the intestinal segments for the substitution of the injured esophagus are described. Positive results were obtained in most cases.

Adolescent↗
PubMed1994

[Surgical treatment of extrahepatic portal hypertension in children].

In the period from 1985 to 1992 sixty-three patients aged from 7 months to 15 years were treated for the portal hypertension syndrome, 60 had the extrahepatie form. Forty-five various operations for portosystemic shunting were carried out: formation of proximal splenorenal anastomosis in 31, distal splenorenal anastomosis in 4, mesentericocaval anastomosis in 6, gastrocaval anastomisis in 2, and an atypical vascular shunt in 2 cases. Nonshunting operations were performed on 8 patients. Since 1986 39 sessions of endoscopic sclerotherapy were conducted, 16 of them were carried out in cases with esophagogastric bleeding.

Adolescent↗
PubMed1991

[Autologous transfusion of UV-irradiated blood in the complex treatment of children with dysplasia of deep veins of the extremities].

Under examination there were 12 patients aged from 5 till 14 years. An investigation of hemostatic potential of blood in the diseased extremity and peripheral blood was performed. A mosaic character of blood coagulative alterations in this category of patients was detected. Autotransfusion of UV-irradiated blood is a pathogenetically grounded and accessible method of correction of hemocoagulation and may be included in the complex treatment of patients with dysplasia of the profound veins of lower extremities.

Adolescent↗