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Biomedical subjects

M Samánek

Publications and source records attributed to M Samánek.

At least 55 records · Page 3Linked to original sources
PubMed1989

The effect of chronic hypoxia on the developing cardiopulmonary system.

The effect of chronic hypoxia (barochamber, 8 h per day, 5 days a week, stepwise up to 7000 m) on some cardiac functional and metabolic parameters was compared in rats acclimatized either from the 4th day or the 12th week of postnatal life. Pulmonary hypertension and right ventricular enlargement were found in both age group. Whereas in young hypoxic animals the weight of the right ventricle increased linearly with the right ventricular pressure, in adult high altitude exposed rats this relation could not be proved. High altitude induced significant increase of concentration of collagenous proteins: in adult animals increased collagen III only, in young also collagen I. The changes of the energy metabolism were similar in both age groups: activity of enzymes of the lactate metabolism and glucose phosphorylation increased; on the other hand, catabolism of fatty acids decreased. Chronic hypoxemia significantly influenced also the myocardial metabolism in children with congenital heart disease; the aerobic capacity was decreased both in the atrial and ventricular tissue; atrial changes were even more pronounced. The type of changes was, however, different from the rat heart.

Acclimatization↗
PubMed1989

Intermittent high altitude--induced changes in energy metabolism in the rat myocardium and their reversibility.

Selected enzyme activities of energy metabolism were studied in the myocardium of laboratory rats exposed to intermittent altitude hypoxia (IAH, 4-8 h daily, 5 days a week, in a hypobaric chamber, stepwise up to 7,000 m). No significant differences were found between the right and the left ventricle in the control animals. Glucose-utilizing capacity (HK) and capacity for the synthesis and degradation of lactate (LDH) increased significantly in both ventricles during acclimatization. The other enzyme activities associated with anaerobic glycolysis (TPDH, GPDH) and those linked up in aerobic metabolism (MDH, CS) did not change significantly. On the other hand, the ability to break down fatty acids (HOADH) decreased significantly. All the above changes in the enzyme profile were found after only 24 4-h exposures, in both the hypertrophic right ventricle and the unenlarged left ventricle. When the length of daily exposure was raised from 4 to 8 h, the above changes were not intensified and 45 days after the last exposure to IAH, none of the given activity values differed from those estimated in the corresponding control animals.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

Effect of the administration of prostaglandins (PGE2) in the early postnatal period on closure of the ductus arteriosus in the laboratory rat.

Maintenance of a patent ductus arteriosus by means of prostaglandins enables the surgical correction of a congenital heart defect in infants to be postponed until a phase of development when the operation hazards are smaller. We investigated the pathophysiological consequences of this therapeutic measure in an experimental model in which E2 prostaglandin was administered to newborn laboratory rats. It was found that, physiologically, the ductus arteriosus (DA) closed progressively within 180 min after birth. The repeated administration of PGE2 (subcutaneously, 15 micrograms.kg-1 every 30 min from the 5th min after birth) blocked closure of the DA, which was still fully patent 300 min after birth. Histological tests showed no significant differences in the structure of the tunica media of the physiologically patent and the PGE2-treated DA. The results show that PGE2 also inhibit physiological closure of the DA in newborn rats. Long-term study of this pathophysiological process is at present impeded by the need for the continuous administration of prostaglandins.

Animals↗
PubMed1989

[The probability of survival in children with heart defects not treated surgically].

Data on the age at death of children with congenital heart disease recorded 27 years before the introduction of cardiacsurgery on a territory where all deceased children were subjected to necropsy and data on the incidence of heart disease in the child population in Bohemia were used to calculate probable survival. Of liveborn infants with heart disease 90% surviev the first week, 86% the first month, 74% six month, 71% the first year and 67% 15 years. Pulmonary stenosis and a ventricular septal defect have the most favourable prognosis. The syndrome of a hypoplastic left heart, double outlow right ventricle, total anomalous pulmonary venous return, arterial truncus and pulmonary atresia have the most adverse prognosis.

Adolescent↗
PubMed1988

Distribution of age at death in children with congenital heart disease who died before the age of 15.

In the 27 years from 1952 to 1979 (before the introduction of advanced cardiac surgery) all children in Central Bohemia (population 1.2 million) who died before the age of 15 were examined at necropsy. Period death rates at various ages were calculated in those with congenital heart disease. Nearly all the deaths (848, 89.6%) occurred in the first year. Forty three (44% of survivors) died in the second year and 17 (31% of survivors) died between the second and fifth years. Over half (20) of the survivors died between the fifth and tenth years. Nearly half (44.2%) of those born with congenital heart disease who died before the age of 15 died in the first four weeks. About a third (29.1%) died in the first week and period death rates were 9.7%, 7.6%, and 5.7% for the second, third, and fourth weeks respectively. In neonates death rates were highest in those with hypoplastic left heart syndrome (89.2%), coarctation of the aorta (66.7%), truncus arteriosus (61.8%), double outlet right ventricle (57.1%), and pulmonary atresia (56.3%).

Adolescent↗
PubMed1987

Lorcainide treatment of Wolff-Parkinson-White syndrome in children and adolescents.

Lorcainide was used in 17 children and adolescents aged 14 days to 18 years (mean 6.8 years) with the preexcitation syndrome (W-P-W type). Lorcainide was able to control attacks of supraventricular tachycardia in eight of 11 patients with the W-P-W syndrome and tachyarrhythmias. Long-term maintenance therapy prevented new attacks of tachyarrhythmia for an average period of nine (5-15) months in all seven patients who tolerated lorcainide administration. Normalization of the W-P-W pattern was reached in nine of 11 children with the W-P-W syndrome who had tachyarrhythmias and in three of six asymptomatic children with the ECG pattern of W-P-W. Single effective doses ranged from 12.5 mg orally in the neonates to 100 mg in the adolescents. The effect of lorcainide on the ECG usually appeared 2 h after the oral administration of the drug. Dizziness in three with insomnia and vomiting in one patient complicated the treatment. No drug-associated abnormalities in blood cell counts and biochemical values were identified.

Adolescent↗
PubMed1987

Infants with critical heart disease in a territory with centralized care.

All children with a critical heart disease in a 6.3 million inhabitants territory were referred and all infants who died were autopsied and the protocols sent to the only Center of Pediatric Cardiology and Cardiovascular Surgery. In the first 5 years of the centralized care, 1,122 infants, i.e. 2.36/1,000 live births suffered from a critical heart disease. 639 (57%) were admitted to the Center and the rest died in provincial hospitals with but not always from a heart disease found at autopsy. An additional 43 (6.2%) patients had nonstructural heart disease and 12 (1.7%) had heart diseases not considered to be critical. The total incidence of critical heart disease fluctuated from 2.15 to 2.51/1,000 live births without any well-defined trend. A decrease in the relative frequency throughout the 5-year period was found for common arterial trunk, pulmonary stenosis and atresia while an increase was observed in patency of the arterial duct. The most frequent critical heart diseases in infancy were: ventricular septal defect (18.2%) - mostly in isolation; complete transposition (14.6%); aortic coarctation (10.0%); hypoplastic left heart syndrome (9.1%) and pulmonary atresia (6.3%). The majority (51.4%) of patients became critically ill or died in the neonatal period. The most common conditions seen in neonates were complete transposition (22.5%), hypoplastic left heart syndrome (16.1%) and coarctation of the aorta (9.5%). The highest share of critically ill patients was encountered in complete transposition (100%), pulmonary atresia (98.7%), common arterial trunk (97.4%) and double outlet right ventricle (92.1%). The least dangerous were atrial septal defect (6.6%), pulmonary stenosis (7.0%), aortic stenosis (12.2%) and ventricular septal defect (21.0%). The mean age was 76 (+/- 56) days at admission and 59 (+/- 73) days at death. Urgent cardiovascular surgery was performed in 235 (36.8%) of the 639 patients admitted in infancy, that is 0.5 per 1,000 live born children.

Age Factors↗
PubMed1986

Causes of death in neonates born with a heart malformation.

All deceased infants were autopsied in a territory with a population of 1 220 000 inhabitants and a mean of 17 410 live births a year. During a period of 25 years (which preceded the introduction of advanced neonatal cardiac surgery), 393 neonates (6% of all deceased neonates) had died in whom a congenital heart malformation was found at autopsy. 118 (30%) of deaths were due to noncardiac causes. Lethal congenital noncardiac malformations caused death in 38 (10%) neonates. A perinatal disease (including birth trauma) was the cause in 65 (16%) neonates. An association of a noncardiac congenital malformation with a perinatal disease was involved in 6 (2%) neonates and a birth weight lower than 1000 g (together with a lethal perinatal disease or alone) was considered responsible in 9 (2%) neonates. Noncardiac but not unambiguously lethal malformations (mostly multiple) could at least have contributed to the fatal outcome in a further 86 (22%) neonates. A low birth weight could have contributed to death in 102 (26%) neonates, particularly in 42 (11%) neonates with a low birth weight associated with multiple noncardiac nonlethal malformations. A most probable or possible noncardiac cause of death was found in all cases of atrial septal defect, in 93% of tetralogies of Fallot, in 84% of ventricular septal defects, in 72% of hearts with double outlet right ventricle and in 57% of those with aortic coarctation. A congenital heart malformation was considered responsible for a fatal outcome in 82% of cases with discordant ventriculoarterial connexions ("transposition of the great arteries"), 79% of hypoplastic left hearts, 68% of pulmonary atresias and 53% of tricuspid atresias. The high proportion of noncardiac death noted to occur in the first postnatal day was found rapidly to decrease in the following days.

Age Factors↗