Cardiac morphology and dynamics in Swedish elite orienteers : Evaluation of the right and left ventricle by two-dimensional and doppler echocardiography

Abstract: Background. Between 1979 and 1992, 16 (15 males and 1 female) sudden unexpected cardiac deaths(SUCD) were reported in Swedish orienteers. Compared with previous reports in young athletes there was a 10- to 100-fold increase in the sudden death rate in young male elite orienteers during this period. The mean age was 25 years (range 18-32 years). Autopsy showed myocarditis to be a common finding, appearing in 75% of the cases of which 62% was unequivocal. One case had arrhythmogenic right ventricular cardiomyopathy and three cases had alterations in either ventricle, suggestive of arrhythmogenic right ventricular cardiomyopathy like disease.Objectives and methods. The purpose of present series of studies was threefold. First, to determine if there was an increase in the occurrence of echocardiographically detectable cardiac abnormalities in male elite orienteers. Second, to explore right ventricular (RV) and left ventricular (LV) morphological changes due to endurance athletics. Third, to compare orienteers with young sedentary adults on Doppler indices of LV and atrial filling.Study populations. The study groups comprised 96 male and 42 female elite orienteers. The control groups included 47 (all adult males) cross-country skiers and middle-distance runners and 61 (32 female and 29 male) healthy sedentary students.Results. LV wall motion abnormalities were found in 9% of the male orienteers and in 4% of the cross-country skiers and middle-distance runners. We were unable to reveal any cases with definite abnormalities in the RV free wall. Compared with the young sedentary adults, male and female orienteers showed symmetrical cardiac enlargement with an concomitant increase in the LV and RV wall. Although none of the male athletes had LV wall thickness >15mm, 13% did show wall thickness >13mm. In the female orienteers LV wall thickness was never >12mm. LV end-diastolic diameter did not exceed 56mm in any of the female orienteers, but a LV diameter >60mm was found in 4.6% of the male athletes. Only one male athlete exceeded 65mm (68mm). No significant differences were observed between the orienteers and sedentary controls on peak transmitral flow, though the orienteers had significantly higher peak pulmonary flow velocity during diastole (0.69 ± 0.13 m.s-1, 0.61 ± 0.10 m.s-1, 0.78 ± 0.12 m.s-1 and 0.57 ± 0.09 m.s-1 for female orienteers and sedentary female controls, male orienteers and sedentary male controls, respectively). The most important independent extracardiac determinants of the left atrial and ventricular filling indices were heart rate, systolic blood pressure and stroke volume in the orienteers and heart rate, interventricular septum thickness and body mass index in the sedentary subjects.Conclusions. LV wall motion abnormalities were commonly found in the male elite orienteers. The orienteers showed a symmetrical cardiac enlargement with an increase in both the RV and LV wall, reflecting the increased haemodynamic loading in endurance athletes. The greater wall thickness in the athletes increases the contractile reserve and decreases wall stress in both ventricles. The Doppler indices of LV and atrial filling suggest a more rapid relaxation and improved LV elastic recoil, which would enable a more rapid negative LV pressure change during early filling in the orienteers.