Cardiological examinations

The evaluation of the conditions of the cardio-circulatory system constitutes the crucial moment of the visit to which every subject who practices sporting activity, whether competitive or not, is subjected. considered physiological or pathological. If this last hypothesis occurs, the task of the sports doctor must be to be able to evaluate [using, in addition to the physical examination, also a series of instrumental tests (electrocardiogram, phonocardiogram, telecheart, echocardiogram )] if the pathological state can give rise to worsening, or if it can somehow expose the subject to sudden unexpected events, such as death or syncope, dangerous both for the subject in question and for those who find themselves having to attend to such conditions.

It is also necessary that the evaluation takes place taking into account the particular type of sport that the subject intends to practice; that is, it is necessary to consider the commitment of the cardiovascular system in that particular type of sport.

ELECTROCARDIOGRAM

Using the electrocardiograph it is possible to record, using special electrodes, the electrical stimuli and transform them into a graphic signal: the electrocardiogram. The paper on which an electrocardiogram is recorded is graphed: horizontally each square corresponds to 0.04 sec; each series of five small squares, delimited by a slightly more marked line, therefore lasts 0.2 sec. The duration of each electrical event is measured horizontally; vertically, on the other hand, the amplitude of the waves is measured: 1 cm corresponds to 1 millivolt.
The currents that excite the heart are the result of a complex ionic movement (in particular of the ions, sodium, potassium, calcium, chlorine) that occurs between the intracellular and extracellular environment.
An electrocardiogram is made up of a series of waves and strokes that are repeated cyclically; the sequence of electrocardiographic elements that make up an electrical cardiac cycle is as follows: P wave - PR segment - QRS complex - ST segment - T wave - possible U wave.
The P wave corresponds to the depolarization of the atria, or to the propagation of the electrical impulse from the sino-atrial node, where it is formed, to all the atrial musculature which consequently contracts; the electrical phenomenon precedes the mechanical phenomenon (ie contraction). While in conditions of rest the P wave has visible limits of duration and amplitude, in the subject under stress these limits can be far exceeded.
The PR segment is measured from the beginning of the P wave to the beginning of the QRS complex, that is the time taken by the electrical stimulus to activate the atria and cross the atrio-ventricular node. In the normal subject its duration is between 0.12 and 0.20 sec, in cross-country skiers it is greater.

The QRS complex is the expression of the depolarization of the 2 ventricles; it too has limits of duration and amplitude. As for the duration, it should not exceed 0.08 sec; as far as the amplitude is concerned, the limits are much more imprecise. In the athlete, however, the increased amplitude of the QRS complex was found.

Finally, the ST segment represents the repolarization of the ventricles.

The electrocardiogram can also be recorded when the subject exerts an effort, pedaling on a cycle ergometer, or walking on a conveyor belt. These recordings are used to evaluate any alterations in the electrocardiogram at rest (doubt of ischemia), or arrhythmias, or when you want to observe cardiac performance during muscular work.

PHONOCARDIOGRAM

The phonocardiogram transforms the noises produced by the heart during its activity into a graphic signal. Usually an electrocardiographic trace is also recorded at the same time, in such a way as to be able to accurately correlate the mechanical events with the electrical ones.
This examination is recorded by affixing a special probe to the chest, which is subsequently moved to the various foci of auscultation. For each outbreak, multiple recordings are made, selecting different acoustic frequencies. The normal noises produced by the heart are the 1st and the 2nd heart sound. The 1st sound is produced by the closure of the atrioventricular valves; the 2nd sound is produced by the closing of the semilunar valves (aortic and pulmonary). Frequently, especially in young athletes, there is a physiological splitting of the 2nd tone, or the presence of an added tone at the beginning of diastole.
The intervals between the 1st and 2nd tone (systolic pause) and between the 2nd tone and the following 1st tone (diastolic pause) are normally silent, but in some cases they may present noises (murmurs) which will be called systolic or diastolic according to the pause they will occupy.
The phonocardiogram is used to evaluate a possible heart murmur with greater accuracy; it will therefore be possible to establish precisely in which part of the cardiac cycle the murmur is located, its intensity and frequency, and the particular morphology. All these elements are useful in distinguishing the so-called innocent or functional murmurs, from those that result from a heart disease. However, it is an examination that is used much less frequently than in the past and that usually adds little to an accurate auscultation with the stethoscope.

TELECU

It is the investigation carried out using X-rays. The distance of the subject from the source of rays must be about 2 m in order to avoid that the excessive divergence of the rays causes distortions or enlargements of the structures whose images would be altered.
Due to the shape of the heart, it is usually not sufficient to make an anteroposterior view, but it is necessary to make oblique and lateral views (left and right anterior oblique, lateral-lateral). While in the antero-posterior projection the contrast between the transparency of the pulmonary fields and the cardiac shadow is sufficient, in the oblique and lateral projections it is no longer so, therefore it is necessary to ingest a radiopaque substance which, by opacifying the esophagus, makes evident on it is the imprint of any enlarged cardiac structures. In the normal subject, the heart can take on different radiological aspects, linked to the biotype, which explain the terminology currently used: horizontal (in the short), oblique (in the normotype) and vertical (in the long-limbed) heart By means of particular calculations, it is possible to obtain the measurement of the cardiac volume starting from the radiographic images. There is no doubt the interest of this data, in particular in the evaluation of athletes: unfortunately, however, the accuracy of the data obtained is not very high, due to some difficulties (such as the need to always perform the x-ray in the same phase of the cardiac cycle, in order to obtain comparable results ) difficult to overcome. Furthermore, in the same subject, the results obtained show a considerable variability.
To obtain the cardiac volume, measurements are used that are taken in antero-posterior projection (height and width of the cardiac shadow) and on the lateral projection (depth), obtained from the subject in horizontal decubitus, since in this position there are fewer volumetric variations .

Finally, Rorher's formula is applied: cardiac surface x maximum depth x 0.63, which becomes 0.4 x length x width x maximum depth in cm.
It should be remembered that from normal values of 700-800 ml of volume, it can be reached in endurance sports athletes to about 1400 ml.

ECHOCARDIOGRAM

Physically, this type of investigation is based on a reflected ultrasonic beam that is picked up by a probe (the same one that emits the ultrasonic beam) and transformed into an electrical signal which, in turn, is converted into a graphic form, giving rise to images that correspond to the various structures of the heart in motion (the free walls of the ventricles, the septa, the valves, the cavities).
Echocardiography can be performed with one-dimensional or two-dimensional technique. In the first case (one-dimensional technique) an isolated sector of the heart is explored from time to time; the spatial resolution is very good and it is possible to carry out a whole series of measurements concerning the size of the ventricles, those of the atria, the amplitude of the valve movements and the quality of these movements. The two-dimensional technique gives us a complete view of the heart in motion, clarifying the spatial relationships that the various structures have between them. The resolving power is, however, lower than the one-dimensional technique.
In conclusion, it can be said that the techniques described above are not to be applied separately, but are both part of a complete echocardiographic examination.

The echocardiographic examination allows to:

- accurately analyze the movements of all cardiac structures;
- carry out rather precise measurements of the dimensions of the cardiac structures, evaluating the relationships existing between them;
- resolve any diagnostic doubts.

Echocardiography allows us to study the adaptation of the heart to different types of sports. In athletes dedicated to endurance sports, the main changes concern the diameters of the heart cavities, which are also significantly increased, while the thickening of the walls is only moderate. These alterations, induced by training, are reversible over a period of 2- 3 months, if training is suspended. In athletes dedicated to power activities, there is above all an increase in the thickness of the ventricular walls.

Curated by: Lorenzo Boscariol