| GUIDE
ARTICLES
Right
ventricular
dysfunction – a possible limiting factor of the exercise
capacity
in top athletes
Pufulete
Elisabeta, Georgescu
Mariana,
Stoian I1, Carp C 2
1
National
Institute of Sports
Medicine Bucharest
2
Institute of
Cardiovascular
diseases ,, C.C. ILIESCU “ Bucharest
Abstract.
We
studied a group of 18 top
athletes (A)
presenting the
alteration of ventricular repolarization in right ventricular area (
mean age of 18 years + 5, mean stage in sport of 6
years +>3,
12 females and
6
males). They practiced long endurance exercise (14) or the resistance
sports (4). We performed ECG at rest and during maximal exercise
(exercise stress testing) by cycloergometer (2,5 – 3 watts /
kg body
weight), two-dimensional echocardiographic investigation at rest and
immediately after exercise. We also studied a witness group of 15 top
athletes (B). Group A presented some signs of R.V. dysfunction: the
increased diastolic and systolic area (p<0,01) modified shape,
the
decreased RV descent (p<0,01). VO We studied a group of 18 top
athletes (A) presenting the alteration of ventricular repolarization in
right ventricular area ( mean age of 18 years + 5, mean stage in sport
of 6 years +2 max. was decreased . We found also an opposite effect of
the maximal exercise on the right and the left ventricles: R.V. area
increased while the left one decreased. This disproportionate effect
was higher in long endurance athletes as compared with the resistance
athletes. The explanation could be a disproportionate increase in R.V.
afterload and an inadequate R.V. preload reserve caused by the
decreased venous return. The changes of the R.V. shape and function
during maximal endurance exercise seem to be a possible limiting factor
of the effort capacity.
Key
Words:
Right Ventricle (R.V.), Left Ventricle (L.V.),
Electrocardiogram (ECG)
, Right Atrium (R.A.), Left Atrium (L.A.), Afterload, Preload, Ejection
Fraction (E.F.).
Introduction
In
recent years, we found a particular electrocardiographic aspect in
top athletes: inverted “T” waves in right
precordial area (V1
to V3 and sometimes V4). Starting from this unexpected
aspect , we extended the cardiological research on the R.V., knowing
that the effects of the maximal exercise are less well studied on
the right than on the left side of the heart (1,2). In fact, the
right heart response to extreme or prolonged exercise is practically
unknown. Confronted with this particular aspect, we asked ourselves:
is it a disadaptive functional state caused by overtraining, or is it
a silent myocardial ischemia – not quite impossible in young
people
over 25 years old, or is it a sign of an isolated R.V. hypertrophic
cardiomyopathy – not rare in people younger than 25 years?
Also we
had to conclude whether it is advisable for these athletes to engage
in top sport.
Method
Study
subjects: we studied periodically about 18000 elite or high level
athletes. Out of them, only 18 subjects presented resting ECG
alterations in R.V. area. This group (A) had the following
characteristics: mean age of 18 years (range 12 to 31), mean stage in
sports activity of 6 years (range 2 to 16), 67% were females and 33%
were males. Distribution on sports showed the greatest prevalence in
swimming and kayak. We did supplementary investigations: clinical and
laboratory biochemical exam (including electrolytes), heart
radiological exams concerning dimensions, configuration and pulmonary
circulation, the aerobic capacity tested by cycloergometer (2,5
– 3
watts / kg body weight) ECG at rest and during exercise. All athletes
underwent two echocardiographic studies, at rest and immediately
after exercise. Two- dimensional echocardiograms were recorded from
apical four chambers view.
This
view allows imaging all cardiac chambers, atrio – ventricular
flow
and assessment of the right and left ventricular systolic
function.The echocardiographic parameters have been corrected
according to age and body weight.
There
were studied right and left end- diastolic and end- systolic
cavities, partly the tricuspid and mitral regurgitation and R.V.
descent: the difference in length on a perpendicular chord between
the endocardium of the R.V. apex and the tricuspid annulus in
end-diastole and end-systole(3).We preferred to study this parameter
knowing that the systolic shortening from apex to base has been found
to correlate with global R.V. function (4),while the tricuspid
annular plane systolic excursion (TAPSE) is closely correlated with
R.V.E.F.(5).We also studied a witness group (B) of athletes
(swimmers) having the normal resting ECG.
Statistical
analysis: Data are presented as mean values +/-standard
deviation (SD).A <0,05 was considered statistically significant.
Results
The
study subjects were clinicaly asymptomatic, biochemical tests and
radiological investigations were also normal .ECG became normal
during exercise on cycloergometer. The aerobic capacity (VO2
max)was smaller as compared with thewitness group.In the study
group, the echocardiographic investigation showed the resting mean
values of the R.V.area bigger than the same mean values found in
witness group.The mean values of the L.V.,L.A.,and R.A.areas were
similar (Table1)
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TABLE
1.
CAVITY AREAS AT REST (cm2)
|
| GROUP
A
Mean
value± DS
| GROUP
B
Mean
value± DS
|
t |
p
| R.V.
end diastolic
| 22.5 ±
4.2 |
18.7 ±
3.6 | 2.75 | <0.01
| R.V.
end systolic
| 15.1 ±
5.2 |
11.2 ±
2.9 | 2.58 | <0.01
| L.V.
end
diastolic
| 38.1
±
7.1 | 37.0 ±
5.1 |
0.50
| >0.05
| L.V.
end systolic
| 26.3 ±
7.1 |
25.8 ±
6.8 | 0.20 | >0.05
| R.A.
end
diastolic
| 11.9
±
2.8 | 11.3 ±
2.8 |
0.61
| >0.05
| R.A.
end systolic
| 19.1 ±
3.0 |
18.8 ±
3.0 | 0.28 | >0.05
| L.A.
end
diastolic
| 11.6
±
4.0 | 11.8 ±
4.0 |
0.14
| >0.05
| L.A.
end systolic
| 20.1 ±
4.8 |
20.0 ±
4.4 | 0.06 | >0.05
|
R.V.
descent was significant smaller. (Table 2) |
TABLE
2. R.V. DESCENT AT REST (cm2)
|
GROUP
A
Mean
value ± DS
| GROUP
B
Mean
value ± DS
|
t p | 1,7
+ 0,2
| 2,0 +
0,2 | 4,29 <0,01 |
Immediately
after exercise both groups presented the mean values of the R.V. area
bigger, while the L.V. area was smaller (Table 3).
|
TABLE
3. CAVITY AREAS AFTER EXERCISE (cm2)
|
| GROUP
A
Mean
value± DS
| GROUP
B
Mean
value± DS
| t
| p
| R.V.
end diastolic
R.V. end systolic
L.V.
end
diastolic
L.V. end systolic
R.A.
end
diastolic
R.A. end
diastolic
L.A. end
diastolic
L.A. end
diastolic
|
25,1 + 5,2
17,1
+ 5,2
36,3
+
6,3
25,1 +
5,9
12,0 +
3,0
18,8 +
3,4
11,2 +
3,1
16,9 + 3,8
| 19,9 + 4,8
14,1
+ 3,8
36,4 +
6,1
24,8 + 5,8
11,5
+
2,8
17,9 + 3,0
11,3
+
3,0
17,2 +
3,9 | 2,96
1,85
0,04
0,14
0,49
0,79
0,09
0,22
| <0,01
<0,01
>0,05
>0,05
>0,05
>0,05
>0,05
>0,05
|
|
|
This
fact is conform to the other studies (6), but we did not find anyone
concerning the possible correlation between the echocardiographic and
electrocardiographic patterns. The dynamic of the altered ECG was as
follows: normalization in 74% cases after a various period of time
without extreme exercise;one case was stationary; one case presented
diffused troubles of ventricular repolarization; one athlete
presented an ectopic ventricular activity (as left bundle branch
block configuration) being the possibility of an arrhythmogenic
R.V.dysplasia. We have to mention three facts:all study subjects with
modified ventricular repolarization in R.V. area had had the previous
normal ECG; this particular aspect was discovered especially in the
precompetitional period, after the long endurance trainings; 15 of
them (83%) had had a long stage in sport. Though we could not study
the atrio-ventricular regurgitations, we noted that tricuspid
regurgitation was nearly unchanged, while the mitral one was severely
decreased. Discussion
The
absence of any clinical symptoms and the normal ECG during the
exercise stress testing seem to exclude a coronarian substrata.
Echocardiographic study does not identify the signs of a
hypertrophic cardiomyopathy.The resting big R.V.area and the
decreased R.V.descent could indicate a possible R.V. dysfunction.In
clinical practice the multivariate analysis revealed that R.V.descent
as a marker of the R.V.dysfunction, was an independent predictor of
adverse outcome in active myocarditis(4.)R.V.dysfunction in
associated with worse L.V.function;it is a possible sign of the
depressed biventricular function.In elite athletes practicing long
endurance exercise ,R.V.dysfunction could be a sign, a signal that
the heart’s physiological adaptive mechanisms are exceeded.In
our
study, normalized ECG after deconditioning period pleads for the
functional transient disadaptive cause.The echocardiographic aspect
found immediately after exercise requires a serious analysis. R.V. as
well as the L.V. must modify its performance according to the
increased circulatory demands of the extreme exercise. It is possible
in certain top athletes that exercise determines the opposite effects
on the right and left ventricles. We found that R.V. enlarges while
the L.V. becomes smaller. The cause of this different response may be
a disproportionate increase of the right and left ventricular
afterload during
and immediately after exercise. This fact was demonstrated by
hemodynamic studies, (7,2) which showed that after extreme exercise
the pulmonary pressure increases by 50% to 70% while the systemic
pressure increases by only 11% to 45%. If the increased afterload is
maintained for a period of time,the R.V.dysfunction can manifest as
dilation (8). Another possible explanation could be a different
preload reserve or venous return. In top athletes, an inadequate
venous return(caused by hyperpnoea) could be compensated by a
sudden,transient R.V. dilation (9).L.V.function may be negatively
affected through a positional shift of the interventricular septum
and abnormal wal motion(10, 11). Limitation
of the study1.It
is difficult to assess R.V.sizes because its geometry does not
conform to a mathematic model. 2.After
extreme exercise,the time for data recording is very limited.
3.We
studied only a particular ECG aspect found in top athletes and its
certain accompanying echocardiographic parameters
4.The
low numer of cases studied does not allow to forward firm
conclusions. Conclusions
1.
Inverted “T’’waves in R.V.area is a rare
and unexpected ECG
aspect in top athletes. It could be a sign of a R.V.dysfunction.
2.
This aspect is more frequent in females (67%); also it appears late
in the sport career, especially after training in long endurance and
high intensity efforts. 3.
Altered ECG patterns disappear or are attenuated in the
deconditioning period. 4.
In study subjects, the echocardiographic investigatins showed an
increase of the R.V.area at rest and after exercise bigger than in
the witness group.R.V.descent was smaller. 5.
The increased R.V.area and the possible changes of its shape and
compliance,also the decreased R.V.descent suggest a certain
R.V.dysfunction, as a possible consequence of the inadequate
R.V.preload reserve. 6.
The possibility that the R.V. dysfunction can be a significant
limiting factor of the effort capacity begin to have more relevance.
7.
The
opposite effects of the exercise on the right and left
ventricles remain a problem to study in a large numer of top athletes
practicing different efforts.The understanding of this problem
could be important both in sports cardiology and in clinical
cardiological practice.
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