**4. Distribution of chemical elements in different parts of the heart and their impact on the development of pathologies in TGA patients**

The following mechanisms were identified when analyzing the content of CE in the deceased infants' myocardium (Table 5A,B).


#### *\* P < 0.05*

Table 5A. Distribution of CE in infants' ventricle with intact myocardium and TGA infants

It follows from Tables 5A and 5B that in 65 % of TGA patients, as compared to those with intact myocardium, the content of CE was reduced: K was lower, down to 78 %, concentration of Cl, Cr, Sr, Zn decreased to 50 % and the concentration of Br, Ni, Rb was also low. The content of Se equalled to just 25 % of the benchmark value. Three CE: S, Ca and Fe had an appropriate concentration. It was found out that only 2 CE had an increased concentration: Cu – 160 % and Mn – 170 to 200 %. According to the distribution of CE in the heart parts, the lowest concentrations of CE were found in LV and RA myocardium.


#### *\* P < 0.05*

336 Congenital Heart Disease – Selected Aspects

In the 1 to 6 and 6 to 12 months old groups, as compared with the newborn group, the following ECHO values were found to increase considerably: RV size, end-systolic volume, systolic output, end-systolic dimension, end-diastolic volume and end-systolic dimension. In addition, there was a trend toward an increase in the size of ASD, VSD and LV thickness. However, the size of unclosed ductus arteriosus tended to decrease. The shortening fraction (SF) and ejection fraction (EF) values matched the age-related indices. The pressure in the pulmonary artery was elevated in all groups, but it was particularly high in the 6 to 12

Clinical/functional examination of TGA patients demonstrated that in terms of basic clinical indicators there were no statistically significant differences between the deceased and surviving infants with TGA. Moreover, average indicators of all 3 age subgroups (newborns, 1 to 6 months old and 6 to 12 months old) in both groups are identical within a time period. From this it follows that negative factors causing the death of infants with TGA are related to molecular disorders of metabolic processes in cardiomyocytes that, in turn, brought us to start studying the content of CE and structural/molecular characteristics of TGA infants'

**4. Distribution of chemical elements in different parts of the heart and their** 

The following mechanisms were identified when analyzing the content of CE in the

Intact myocardium TGA patients' myocardium

S 3380±631 3260±335 3268±424 3547±331 Cl 842±311 624±142 405±45\* 435±56 K 792±257 630±133 508±60 560±55 Ca 1352±218 1264±94 1256±89 1224±99 Cr 1.0±0.22 0.9±0.12 0.4±0.15\* 0.6±0.23 Mn 2.4±0.2 2.4±0.2 2.6±0.8 5.1±2.0 Fe 344±30 422±83 321±42 342±33 Ni 0.4±0.05 0.6±0.09 0.2±0.03\* 0.2±0.05\* Cu 8.9±0.68 10.1±0.87 14.6±2.99 16.1±2.58 Zn 360±39 392±43 240±22\* 307±42 Se 0.7±0.1 0.8±0.1 0.2±0.05\* 0.1±0.04\* Br 12±1.6 13±1.6 6±0.7\* 8±0.8\* Rb 1.4±0.23 1.4±0.18 0.8±0.20 0.6±0.08\* Sr 6.1±0.7 6.3±0.6 3.7±0.7 3.8±0.5\*

Table 5A. Distribution of CE in infants' ventricle with intact myocardium and TGA infants

Left ventricle (n=15)

Right ventricle (n=20)

Right ventricle (n=5)

**impact on the development of pathologies in TGA patients** 

deceased infants' myocardium (Table 5A,B).

Left ventricle (n=5)

months old group.

myocardium.

Parts of the heart

Content of CE, µg/g

*\* P < 0.05* 

Table 5B. Distribution of CE in infants' atrium with intact myocardium and TGA infants

Hence, irreversible hemodynamic disorders of the myocardial function and development of cardiac insufficiency might be connected with a low concentration of Cl, Cr, Sr, Zn, Br, Rb, Ni and specifically Se, which in this case drops to 25 % and even beyond the measurement limit. An increased content of Mn and Cu mostly in the right parts of the heart could be explained by an elevated functional load and plays a compensatory role. The content of S, Fe and Ca matches the benchmark values and does not affect the changes in the myocardium. On the basis of the results obtained it may be concluded that in order to maintain normal functional activity of the myocardium in TGA infants, the content of Cl, Zn, Sr, Cr, Ni, Rb, Br and especially Se that protects cardiomyocytes from lipid peroxidation should be optimal. The following relationships were revealed while comparing CE impoverishment in the myocardium of TGA infants in different heart parts (Table 6).

Chemical Elements and Structural/Molecular

of RV exceeded that of LV by 133 % (Table 7).

0.60 ±0.15

0.60 ±0.12

\* - Reliability of correlation relationship (p<0.05) \*\* – Reliability of correlation relationship (p<0.01)

Wall thickness, cm

> 0.61 ±0.17

> 0.55 ±0.14

Heart's mass, g\*

> 52.6 ±8.31

> 48.7 ±9.33

\* The norm is 24±0.15 g

chemical elements

with IVS (Table 8).

Group

1st group

2nd group

Properties of Myocardium in Infants with Transposition of Great Arteries 339

decreased concentration of microelements. These changes were more pronounced in the left parts of the heart. These results were also confirmed by the morphological examination data. Hypertrophic changes in the heart make rapid strides over age, exceeding the benchmark age values by 2 times at the age of up to 1 month and by 3.5 – 4.5 – at the age of 6 to 12 months. At the same time, the linear dimensions of LV and RV in patients with IVS (first group) were practically identical, while in the VSD group (second group) the thickness

Muscle fibre

11.65 ±2.12

11.90 ±3.11

Heart part Anatomic group S K Fe Cu Sr Zn RV 1st group 0.15 0.09 0.58\* -0.26 -0.19 0.12

Table 8. Correlation relationships (r) between myocardium thickness and content of some

A statistically reliable relationship between LV myocardium thickness and the content of S, K, Fe, Sr and a negative correlation relationship with Cu were revealed for the first group

According to our data, an impaired myocardial function in TGA infants resulting in death might be related to a considerable reduction of metabolism, the markers of which appeared to be a lowered content of Br, Ni, Rb (down to 50 %), Cr, Sr, Zn, Cl (down to 60 %) and particularly Se (down to 25 %). What role do these CE play in myocardium metabolism in TGA infants? Some of these CE are mostly of an endonuclear nature (Cr, Mr, Ni), while others are found outside the nucleus and accumulated in microsomes, mitochondria, lysosomes and Golgi's complex (Cu, Zn, Se, Br, Sr) (Kudrin et al., 2000). Of great importance is Zn, which activates more than 300 enzymes and is part of over 200 metalloproteins (Skalny, 1999; Beerli, 2000). Zinc deficiency results in the development of congenital heart diseases (Panchenko, 2004), Br plays an important role in the development of a foetus and its shortage leads to a greater number of miscarriages. Ni might be a co-factor of many enzymes: urease, hydrogenase, a number of dehydrogenases and methyl-coenzyme Mreductase, while its deficiency affects metabolic processes in the cells. It was found out that

LV 1st group 0.92\*\* 0.75\*\* 0.82\*\* -0.92\*\* 0.67\*\* -0.18

Table 7. Cardiometric parameters of TGA newborns (first and second groups)

diameter, µm Inflow, cm Outflow, cm

2.6 ±0.24

2.8 ±0.36

3.6 ±0.61

3.6 ±0.52

3.7 ±0.47

4.0 ±0.54

RV LV RV LV RV LV RV LV

2.5 ±0.41

2.5 ±0.21

11.85 ±1.95

11.60 ±2.55

2nd group 0.31 0.15 -0.29 -0.60\* 0.13 0.08

2nd group 0.46 0.47 0.50 -0.33 0.30 -0.25


Table 6. CE impoverishment in the heart parts of TGA infants

It was found that in the hypertrophied myocardium of LV (and RV) there was a decreased content of K, Cl, Zn, while the content of S, Fe and Ca remained at an adequate level (see Fig. 1).

Fig. 1. Distribution of CE in LV of TGA infants, CE are arranged by concentration decrease.

The concentration of microelements Cr, Rb, Ni, Se was notably lowered, while the remaining CE had values that were close to the benchmark ones. The data obtained led us to conclude that the hypertrophied myocardial function in TGA infants was impaired due to a decreased concentration of microelements. These changes were more pronounced in the left parts of the heart. These results were also confirmed by the morphological examination data. Hypertrophic changes in the heart make rapid strides over age, exceeding the benchmark age values by 2 times at the age of up to 1 month and by 3.5 – 4.5 – at the age of 6 to 12 months. At the same time, the linear dimensions of LV and RV in patients with IVS (first group) were practically identical, while in the VSD group (second group) the thickness of RV exceeded that of LV by 133 % (Table 7).


\* The norm is 24±0.15 g

338 Congenital Heart Disease – Selected Aspects

It was found that in the hypertrophied myocardium of LV (and RV) there was a decreased content of K, Cl, Zn, while the content of S, Fe and Ca remained at an adequate level (see

Fig. 1. Distribution of CE in LV of TGA infants, CE are arranged by concentration decrease. The concentration of microelements Cr, Rb, Ni, Se was notably lowered, while the remaining CE had values that were close to the benchmark ones. The data obtained led us to conclude that the hypertrophied myocardial function in TGA infants was impaired due to a

CE

Mean m Mean m Mean m M m S 3268 424 S 3547 331 S 2398 330 S 2505 260 Ca 1256 89 Ca 1224 99 Ca 1148 105 Ca 1109 86 K 508 60 K 560 55 K 444 58 K 421 38 Cl 405 45 Cl 435 56 Cl 348 43 Fe 375 38 Fe 321 42 Fe 342 33 Fe 338 53 Cl 290 42 Zn 240 22 Zn 307 42 Zn 183 21 Zn 192 27 Cu 14.6 2.99 Cu 16 2.58 Cu 13 2.18 Cu 14.3 2.7 Br 6 0.7 Br 8 0.8 Br 6 0.7 Br 6 0.6 Sr 3.7 0.7 Mn 5.1 5 Sr 3.2 0.3 Mn 4.2 1.4 Mn 2.6 0.8 Sr 3.8 0.5 Mn 3.1 1.1 Sr 3.5 0.4 Rb 0.8 0.2 Rb 0.6 0.08 Cr 0.6 0.25 Cr 0.7 0.18 Cr 0.4 0.15 Cr 0.6 0.23 Rb 0.5 0.1 Rb 0.5 0.07 Ni 0.2 0.03 Ni 0.2 0.05 Se 0.2 0.06 Se 0.2 0.05 Se 0.2 0.05 Se 0.1 0.04 Ni 0.2 0.04 Ni 0.2 0.04

LA

CE

RA

RV

CE

Fig. 1).

LV

CE

Table 6. CE impoverishment in the heart parts of TGA infants

Table 7. Cardiometric parameters of TGA newborns (first and second groups)


\* - Reliability of correlation relationship (p<0.05)

\*\* – Reliability of correlation relationship (p<0.01)

Table 8. Correlation relationships (r) between myocardium thickness and content of some chemical elements

A statistically reliable relationship between LV myocardium thickness and the content of S, K, Fe, Sr and a negative correlation relationship with Cu were revealed for the first group with IVS (Table 8).

According to our data, an impaired myocardial function in TGA infants resulting in death might be related to a considerable reduction of metabolism, the markers of which appeared to be a lowered content of Br, Ni, Rb (down to 50 %), Cr, Sr, Zn, Cl (down to 60 %) and particularly Se (down to 25 %). What role do these CE play in myocardium metabolism in TGA infants? Some of these CE are mostly of an endonuclear nature (Cr, Mr, Ni), while others are found outside the nucleus and accumulated in microsomes, mitochondria, lysosomes and Golgi's complex (Cu, Zn, Se, Br, Sr) (Kudrin et al., 2000). Of great importance is Zn, which activates more than 300 enzymes and is part of over 200 metalloproteins (Skalny, 1999; Beerli, 2000). Zinc deficiency results in the development of congenital heart diseases (Panchenko, 2004), Br plays an important role in the development of a foetus and its shortage leads to a greater number of miscarriages. Ni might be a co-factor of many enzymes: urease, hydrogenase, a number of dehydrogenases and methyl-coenzyme Mreductase, while its deficiency affects metabolic processes in the cells. It was found out that

Chemical Elements and Structural/Molecular

intensity in fluorescence (see Fig. 2B).

during the postnatal period.

Properties of Myocardium in Infants with Transposition of Great Arteries 341

Depending on the anatomic type, 2 groups of TGA patients prevail: the first group, the socalled simple TGA form, TGA with atrial septal defect (ASD) and intact ventricular septum

From the point of view of hemodynamics, the first group of TGA patients with IVS features a two-directional shunt, the volume of which, when performing isolated shunting on the level of atria, will depend on compliance of atria, a pressure differential in them during different phases of the cardiac cycle, size of atrial defect and a difference in resistance of the systemic and pulmonary circulation. Since the systemic circulation and pulmonary circulation are separated, the main compensation strategy is to increase the volume of circulating blood, which leads to overflow of the pulmonary circulation system (Adkin et al., 2002). In this anatomic type of TGA, the functional load on the ventricles is practically the same, which is confirmed by the results obtained while staining the myocardium with ethidium bromide. These results indicate that the peak of active synthesis of genetic material uptake in both ventricles in this group, as compared to that in the control group (see Fig. 2A), occurs during the neonatal period and manifests itself as a dramatic drop in colour

The second group of TGA patients with VSD is hemodynamically characterized by the presence of 2 defects, on the level of atrial and ventricular septa, which improves blood mixing on the ventricular level due to crossed shunting. With VSD size being small, the pressure in pulmonary circulation grows slightly, when the size of VSD is large, the pressure in both circulation systems is levelled out which results in high pulmonary hypertension (HPHT) and augmentation of hypoxemia (Bokeria, 1996; Isoyama et al., 1987). In this anatomic type of TGA, due to an increase in the blood volume, both ventricles are subject to a large functional load as compared with the first group of patients, which makes itself evident in a reduced level of fluorescence in infancy (1 to 6 months old). From our point of view, this phenomenon can be defined as the start of the heart remodelling processes, which at the age of older than 6 months also include hyperplastic processes. These processes are related to polyploidization of nuclear material and subsequent hypertrophic phenomena determined by appropriate hemodynamic conditions developed

Fig. 2A. Control group (up to 1 month). LV myocardium. Magnification 260. Filter set 14.

BP510-560nm. FT580. LP 590nm. Staining with ethidium bromide.

(IVS), and the second group, which includes TGA patients with ASD and VSD.

the activity of b-DNA-polymerase directly depends on the content of Cr, a vital chemical element (Panchenko, 2004). Cr deficiency is observed in premature infants, whose mothers do not get enough of it in their diet. Chlorous channels can be found in mitochondrial membranes and muscle tissue. Also, chloride ions regulate the liquid volume and stabilize pH of the cells (Sing & Snow, 1998). Rb is an analogue of K and together with Cl they are very active in redoxreactions. A considerable deficiency of Se, which protects cardiomyocytes from detrimental effects of free radicals, has the greatest impact on cardiomyocyte metabolism. A decrease in muscle mass and a developmental lag were observed in newborns whose mothers were short of Se during pregnancy (Panchenko et al., 2004). In the case of Se deficiency, the cells start dying both in the form of apoptosis and necrosis, which might result in the sudden death of newborns (Azoicai et al., 1997; Bolli, 2002). On the strength of these data, we suggest that a very low content of CE, and Se in particular, in the myocardium could lead to structural disorders in the development of heart parts and, consequently, to deaths among TGA infants.
