Dr.Biol., Professor E.V. Eliseev
Dr.Biol., Associate Professor E.G. Kokoreva
Dr.Hab., Professor P.I. Kostenok
Ural State University of Physical Culture, Chelyabinsk

Keywords: functional systolic murmurs, mitral valve prolapse syndrome, phonocardiography, echocardiography, 16-20-year-old athletes and non-athletes.

Introduction. The importance of assessment of young people’s functional systolic murmurs (FSM) in today’s health care [1, 5, 6] and clinical medicine [2, 7] practice can hardly be overestimated. However, systolic murmurs are observed most often in young athletes [4, 8], while variability of detecting FSM, according to different authors, varies from 50 to 92% depending on the sport [1, 3]; sport record [4, 8]; health care support level [3, 7] and quality of medical and pedagogical control [9] at all stages of sport training.

Commonly distinguished pathological systolic murmurs are physiological and functional ones [3, 6]. The latter may be a manifestation of early signs of various myocardial disorders in young people. The often mentioned disorders include myocardial dystrophy as a result of chronic physical overstrain [2]; myocardial or myodistrophic cardiosclerosis [10]; intoxication from centers of chronic infection [7, 9].

Phonocardiography (PCG) is the main instrumental method of differential diagnostics of FSM [3, 6]. However, according to [2, 7], PCG-criteria of differential diagnostics of physiological and pathological FSM do not always make it possible to reliably distinguish between these types of murmurs.  However, diagnostics of pathological or physiological FSM largely determines medical tactic towards athletes [1]. Emergence of echocardiography (echo) in the second half of the twentieth century enabled sport medicine to approach solving the issues of diagnostics and FSM assessment at a new methodological level [3, 7]. Therefore, according to [2, 9, 10], the use of echo, especially in combination with other instrumental methods of heart studies, and first of all with PCG, to address the issue of the origin of FSM in young people not doing sports as well as in athletes, is still promising.

Historically, in early 80s of the last century, making the first, pioneering attempts to use echo for assessment of systolic murmurs in athletes, A.G. Dembo and E.V. Zemtsovskiy noticed that bulging of one or both mitral valve (MV) leaflets was often observed in their subjects aged 16-20 during systole, that is their prolapse into the cavity of the left atrium in the absence of any organic lesion of the valve [3]. At the same time it was the first time they identified a connection between the mitral valve prolapse syndrome (MVPS) and systolic murmur in athletes. However, neither this nor further studies we know about provided answers to questions about the frequency and prevalence of the syndrome among young non-athletes and athletes, their peers. The link between MVPS and systolic murmurs in young athletes as well as in young people with early heart disease has not been comprehensively analyzed until now. That is why, even though there have been rather many studies dedicated to diagnostics and FSM assessment in young people in the last 40 years, we consider the issues of diagnostics and clinical assessment of FSM in healthy 16-20-year-old non-athletes, as well as in young athletes – their peers, relevant and timely.

Objective of the research was to study the effect of MVPS on the diagnostics and FSM assessment in healthy young people not doing sports and athletes – their peers.    

Research methods and structure. In order to achieve this goal 639 athletes aged between 16 and 20, of various sport skill levels, with different orientation of the training process, and 90 young healthy persons of the same age, not doing sports (military school cadets), were examined.

In addition to clinical examination that included a thorough auscultation, all the subjects had electrocardiography (ECG) and PCG done. ECG was recorded in 12 standard leads [3], and at the same time there was performed continuous recording of 100 cardiac cycles in order to detect cardiac rhythm disturbances. All the subjects with systolic murmurs or systolic click detected during the auscultation had an additional echo research done with recording in 4 standard leads for detailed results. The echo research was performed on modern equipment IMAGIC SIGMA 5000 (KONTRON MEDICAL, France) in the functional diagnostics department of Federal Government Budgetary Healthcare Institution Central Occupational Health Facility № 15 of the Federal Medical-Biological Agency of the town of Snezhinsk (Chelyabinsk region). A heart ultrasound was performed in M-mode, its scanning hallmarks being high time resolution and a possibility to visualize the smallest characteristics of the heart structures. This ultrasound was carried out in 4 standard positions in accordance with a method that is widely spread and described in specialized literature [7]. Movements of the mitral valve leaflets were assessed in the second standard position. MVPS was diagnosed based on abnormal movement of one or both leaflets behind into the ventricular systole. However, according to the recommendations [9], a track retroflexion by at least 2 mm and of at least 0.05 s long systole was considered abnormal. During mathematical and statistical processing of the research results differences were considered significant if   p<0.05.

Research results and discussion. Systolic murmurs of various location and intensity were detected in 136 (21.28%) athletes and 21 (23.33%) non-athletes. In terms of systolic murmurs location the subjects were distributed as follows: in 66 (48.52%) athletes and 9 (42.85%) non-athletes the systolic murmur was located mostly above the apex of the heart and at Botkin-Erb’s point, while in 70 (51.47%) athletes and 12 (57.15%) non-athletes it was above the cardiac base (see Figure 1).

We used both absolute and relative criteria to assess the intensity of systolic murmurs by means of PCG [3]. The murmurs were considered high-amplitude if the amplitude exceeded 10 mm. The ratio of the amplitude of the first tone and the murmur was also taken into account, which was especially important in case of weakening of the first tone. The amplitude of the systolic murmur was to exceed 1/3 of the amplitude of the first tone. If the above mentioned criteria were lacking, the murmurs were considered low-amplitude. Low-amplitude systolic murmurs were observed about two times more often than high-amplitude ones, regardless of their location, both in athletes and those not doing sports. Thus, the quantitative aspect of the examined individuals adjusted itself. Only 264 athletes out of 639 (136 – with detected systolic murmurs and 128 – with detected but low-amplitude murmurs according to PCG) and the same 90 non-athletes were involved in further echo research. Three hundred and fifty-six echocardiograms were obtained at this stage of the research. MVPS is significantly more often detected both in athletes and non-athletes who have systolic murmurs. At the same time the results obtained do not allow to conclude that sports contribute to MVPS development, since the number of observations is insignificant (less than 100,000). MVPS was detected only in 39 (14.77%) athletes out of 264 subjected to echocardiography versus 10 out of 90 examined non-athletes (11.11%) (see Figure 1).

A clear connection of MVPS with systolic murmurs localized above the apex of the heart and at Botkin-Erb’s point is detected in athletes and non-athletes depending on the systolic murmurs location. As for the systolic murmur above the cardiac base, due to insufficient number of observations (less than 100,000) we cannot associate them with MVPS, since the latter is found under these circumstances as often as in case of the normal auscultatory picture [2].

Figure 1. Frequency of MVPS detection in athletes and non-athletes depending on the systolic murmurs location: 1 – those who do not have any systolic murmurs; 2 – those having systolic murmurs above the apex of the heart and at Botkin-Erb’s point without MVPS; 3 – those having systolic murmurs above the apex of the heart and at Botkin-Erb’s point in combination with MVPS; 4 – those having systolic murmurs above the cardiac base without MVPS; 5 – those having systolic murmurs above the cardiac base in combination with MVPS (see % ratio in the paper).  

However, in terms of both the frequency and location of the systolic murmurs among athletes and non-athletes, the authors obtained a close correlation between changes of the studied parameters in both of the groups: r=0.783 and r=0.862, respectively. Phonocardiographic analysis of the systolic murmurs identified in case of the mitral valve prolapse syndrome proved that, they are normally diamond-shaped or spindle-shaped. In 83% of cases the systolic murmurs had a clear interval I tone – murmur and, as a rule, there was an interval murmur – II tone. The greatest amplitude of the systolic murmur was recorded at S-characteristic. A systolic click was observed in 31% of the subjects with the mitral valve prolapse syndrome. In half of the cases it was possible to distinguish it at the background of the systolic murmur. It is important to emphasize that in a number of cases MVPS on PCG is not accompanied by any auscultatory phenomena. There is mentioning of “silent” cases of MVPS in specialized literature [2, 6, 9, 10].

Conclusion. The use of echocardiography in the assessment of the systolic murmur above the apex of the heart and at Botkin-Erb’s point in athletes and non-athletes showed a close connection of systolic murmurs with prolapse of mitral valve leaflets into the cavity of the left atrium. Further, larger studies are necessary to further clarify the clinical significance of MVPS, its impact on the development of prepathological abnormalities and pathological conditions in 16-20-year-olds when doing sports.  

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Corresponding author: keg-28@mail.ru

Abstract

Analysis of the relevant literature shows that the relation between the mitral valve prolapse syndrome and systolic murmurs in young athletes has not been fully analyzed yet. In order to approach the issue 639 athletes aged between 16 and 20, of various levels of sport skills, with different orientation of the training process, and 90 young healthy persons of the same age, not doing sports (military school cadets), were examined. Study of the influence of the mitral valve prolapse syndrome on the diagnostics and assessment of the functional systolic murmurs in young athletes and non-athletes has shown that the use of echocardiography in the assessment of the systolic murmur above the apex of the heart and at Botkin-Erb’s point allows to reveal the greatest amplitude of the systolic murmur which is more accurately recorded at S-characteristic, which is where a systolic click on a phonocardiogram was observed in 31% of the subjects with the mitral valve prolapse syndrome. In terms of the frequency and location of the systolic murmurs among athletes and non-athletes, the authors obtained a close correlation between changes of the studied parameters in both groups: r=0.783 and r=0.862, respectively. Phonocardiographic analysis of the systolic murmurs identified in case of the mitral valve prolapse syndrome proved that they are normally diamond-shaped or spindle-shaped. In 83% of cases the systolic murmurs had a clear interval I tone – murmur and, as a rule, there was an interval murmur – II tone.