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Biomedical subjects

V S Chekanov

Publications and source records attributed to V S Chekanov.

At least 55 records · Page 3Linked to original sources
PubMed1976

[Electrocardiographic diagnosis of patent ductus atrio-ventricularis].

The paper deals with the diagnosis of defective development of the patent ductus atrioventricularis. Electrocardiographic changes in 81 patients with firmly established hemodynamic form of the patent ductus atrioventricularis, ascertained during surgery and catheterization, are summarized. Characteristic electrocardiographic signs of the defect distinguishing it from other congenital diseases and differential-diagnostic symptoms of diverse anatomo-hemodynamic forms of the patent ductus atrioventricularis were educed.

Adolescent↗
PubMed1975

[Electro- and phonocardiographic changes in cases of a common arterial trunk].

Analysing the data of the examination of 27 patients with a common arterial duct the authors studied the phono- and electrocardiographic changes observed in this cardiac defect. The probable phono- and electrocardiographic signs of this pathology are described the criteria that permit to suspect the presence of a common arterial duct are presented.

Adolescent↗
PubMedDate not supplied

Is it possible to perform immediate cardiac assist using untrained latissimus dorsi muscle in a work-rest regimen?

The authors investigated what contractile force (CF) could be obtained from unconditioned latissimus dorsi muscle immediately after mobilization and for the 2 week vascular period of recovery. Latissimus dorsi muscle mobilization was performed on seven adult (4 experimental and 3 control) sheep leaving only the pedicle and the peripheral muscle intact. Telectronics stimulators (Myostim 7220; Teletronics Pacing Systems, Inc, Englewood, CO) were implanted. Immediately after mobilization 11-35% of the initial CF was lost. A 30 min fatigue test was performed 1 hr after mobilization (20 g/kg preload, 10 V, 10 Hz, 15 BPM, 6 impulses per burst) using a 1 min work-1 min rest regimen. Two sheep lost 2-12% of initial CF; two increased CF by 14-24%. At the end of the fatigue test, CF consisted of 74-89% of immobilized CF. Electrical stimulation training of the muscle was then initiated with the following regimen in the experimental animals only: 15 BPM, single impulses, 5 V, 10 Hz. Every day the muscle was exercised using a work-rest regimen to mimic cardiac assist, starting with 20 min on day 2, and increasing by 2 min per day until a total of 50 min was reached on day 16. All animals were retested for CF using a 42 min fatigue test on days 6, 11, and 16. On day 6, there was no fatigue evident in the experimental group during the 42 min test. CF after testing was 59-81% (mean 67%) of initial data. In the control group (animals with no electrical stimulation training protocol), CF decreased by 11% (from 64 to 53%). On day 11, there was no fatigue evident in the experimental group; CF in all animals increased by 2-8%. On day 16, there was also no fatigue evident in the experimental group; CF increased by 0-9%. An additional 20 min of continuous contraction (15 BPM) fatigue testing was performed on the muscle without rest between the tests. No fatigue was evident at the end of testing. Light microscopic analysis of latissimus dorsi muscle biopsy specimens taken on the days of testing showed no evidence of necrotic damage. Our investigations suggest that it may be possible to start muscle transformation immediately after mobilization and use the untrained latissimus dorsi muscle for cardiac assist immediately after surgery for short periods.

Animals↗
PubMedDate not supplied

Force enhancement of skeletal muscle used for dynamic cardiomyoplasty and as a skeletal muscle ventricle.

Some patients with pre end-stage congestive heart disease do not receive a significant hemodynamic benefit from dynamic cardiomyoplasty because, during prolonged preoperative immobilization, their latissimus dorsi muscle (LDM) becomes extremely weak. It is the authors' hypothesis that the local administration of an anabolic steroid into an electrically stimulated LDM will produce a thicker and stronger muscle with significant resistance to fatigue. The electrical stimulation training protocol of sheep continued for 8 weeks. For localized anabolic steroid administration an osmotic pump was placed in a subcutaneous pocket and the catheter was introduced into the LDM. The contractile force of electrically stimulated and unstimulated control muscle was studied. Control data were calculated as 100% and all other data were corrected to control. After 4 weeks there was no decrease in contractile force. The change seen was from 88 to 100% with different preloads (10, 15, and 20 g/kg) and amplitudes of impulses (5 and 10 V). After 8 weeks, the LDM was more powerful than before electrical stimulation, with a change of 97-133%. Usually after 8 weeks of electrical stimulation alone, contractile force decreases to 70-75%. During a fatigue test (30 min, 100 bursts per minute, 10-25 Hz, ripple frequency, 10 V impulse amplitude) after 4 and 8 weeks of our protocol, the LDM lost only 12% of its initial force, whereas control muscle lost 40%. Thus local anabolic steroid administration makes the LDM stronger and more useful for cardiomyoplasty.

Animals↗
PubMedDate not supplied

Biologic glue increases capillary ingrowth after cardiomyoplasty in an ischemic cardiomyopathy model.

The authors investigated the multi-step mechanism of healing after cardiomyoplasty, focusing on the process of angiogenesis. The authors contend that enhancement of angiogenesis and prevention of ischemia-reperfusion injuries immediately after muscle mobilization will be effective in improving cardiomyoplasty results. After cardiomyoplasty, autologous biologic glue (ABG) was administered between the latissimus dorsi muscle (LDM) and myocardium. By 2 months, a new pseudo interlayer was present that bridged the gap between the LDM and myocardium. Neovascularization was visible in the form of numerous small capillaries. Marked degeneration of the LDM was noted, possibly caused by muscle ischemia-reperfusion damage after mobilization. Pockets were created of ischemic and nonischemic LDM to test for angiogenesis. One was left free of ABG (control); one received ABG only; one received ABG and pyrrolostatin. Some of the capillaries were large and had erythrocytes inside. biopsy samples showed 9.4 +/- 1.9% of the sample was occupied by blood vessels (compared with 3.6 +/- 0.7% in control muscle). These preliminary studies prove the feasibility of the authors' concept and provide evidence that angiogenesis can accelerate the healing process and provide an organic bridge between the LDM and myocardium after cardiomyoplasty.

Adhesives↗
PubMedDate not supplied

Skeletal muscle of a growing organism has a greater transformation after electrical stimulation than adult skeletal muscle.

Six adult sheep and four newborn lambs (5 days old) were implanted with stimulator leads into the latissimus dorsi muscle and connected to a Myostim 7220 pacing system (Telectronics Pacing Systems, Inc., Englewood, CO). Electrical stimulation was started immediately after the operation. After 8 weeks of electrical stimulation, contractile force (CF) in adult sheep decreased to 76-81%, and to 78-82% in lambs. After 2 weeks' delay, CF in adults was 96-98%, and only 89-93% in lambs. After a 30 min intensive stress test, unconditioned control muscle lost 39% in lambs and 43% in adults. Muscle conditioned for 8 weeks lost 7-8% CF. However, after 2 weeks' delay, CF in adult muscle lost 33%, but only 12% in lambs. After cessation of electrical stimulation, the LDH-5 and LDH-1 + 2 fractions reverted to initial levels in adults, whereas in lambs, these levels continued to follow trends established during electrical stimulation. In both adults and lambs, the percent area occupied by the mitochondria increased during electrical stimulation by 6.9% in adults and 6.5% in lambs. After electrical stimulation cessation, the percent area in adults returned to baseline levels, whereas it continued to be elevated in lambs (3.3% vs 5.1%, respectively). The transformed muscle of the lamb did not revert to baseline levels after a delay period.

Adaptation, Physiological↗
PubMedDate not supplied

Angiogenesis in the latissimus dorsi muscle using different regimens of electrical stimulation and pharmaceutical support.

It is our contention that the prevention of ischemia-reperfusion injuries immediately after latissimus dorsi muscle (LDM) mobilization and enhancement of angiogenesis will be effective in improving cardiomyoplasty results. The investigations were performed on adult sheep. Three hours after LDM mobilization, various stages of leukocyte-endothelium interaction were revealed: leukocytes binding to the endothelium, leukocyte destruction of endothelium, and leukocytes leaving capillaries through gaps in the endothelium. Fifty-six days after mobilization various stages of necrosis were discernible. The area occupied by capillaries was 3.45 +/- 0.26% vs. 3.99 +/- 0.24% in control muscle; most of the endothelial cells exhibited morphologic degeneration. Electrical stimulation with 60 CPM actually decreased the capillary density to 2.15 +/- 0.7%, and most of the endothelial cells were damaged, with disrupted plasma membranes. Muscle subjected to 15 CPM increased the percent of capillaries to 5.01 +/- 0.56%, and endothelial cells appeared normal in ultrastructure. Pharmaceutical support prevented muscle damage and accelerated revascularization. After 56 days of autologous biological glue (ABG) application, the area occupied by capillaries was 5.57 +/- 0.24%. This increased to 8.47 +/- 0.72% when aprotinin (proteinase inhibitor) was added to ABG, and to 9.40 +/- 1.24% with pyrrolostatin (free radical scavenger). Both ABG application with aprotinin and electrical stimulation at 15 CPM prevent the LDM from postmobilization damage, and increase angiogenic potential.

Animals↗
PubMedDate not supplied

Age related skeletal muscle response to electrical stimulation.

We hypothesized that the conditioned muscles of elderly and growing organisms have different responses to electrical stimulation from that of young adult organisms. Five day old lambs, 1 year old sheep, and 8 year old elderly sheep were used for this investigation. The latissimus dorsi muscle (LDM) was partially mobilized and left in situ. Two electrodes were implanted and electrical stimulation (ES) was begun for 8 weeks; it was then stopped for 2 weeks. Biopsies were taken before ES, after 8 weeks of ES, and after the 2 week delay period. The LDM of old sheep has less fatigue resistance than the LDM of younger animals. Conditioned LDM of the lamb continued to be fatigue resistant after a 2 week delay compared with adult sheep. In all animals, lactate dehydrogenase (LDH) fraction five decreased and LDH-1 + 2 fractions increased after ES. After a 2 week delay, the data returned to baseline values only in adult animals. The percentage area occupied by mitochondria in old sheep was less after ES than in younger animals. In all animals, the mitochondrial area increased after ES and reverted to baseline values after the delay. The number of nuclei and fibers considerably increased after ES. Only in the lamb did the number of nuclei and fibers continue to be elevated after the delay. There are more changes in young skeletal muscle than in adult (1 year or 8 year old) muscle during ES, and they "remember" these properties. Elderly skeletal muscle does not convert to a fatigue resistant state as completely as adult skeletal muscle during a conventional 8 week ES protocol. It is necessary to change and prolong the ES protocol for elderly patients.

Aging↗