Faculty Bibliography

Robust estimates of the "true" bivariate relationship between body size (X) and heart size (Y) have seldom been determined empirically. The removal of the covariate influence of body size from cardiac dimension variables facilitates both correct inter- or intra-group comparisons, and the construction of reference standards for normality. In the literature to date this "scaling" or normalisation of cardiac dimensions has been performed typically via a per-ratio standards method, (Y/X), with body surface area chosen as the size denominator. This review demonstrates that the per-ratio standards approach may be theoretically, mathematically, and empirically flawed. The most appropriate scaling procedure appears to be a curvilinear, allometric model of the general form Y = aXb. The cardiac dimension variable (Y) may be regressed upon the body size variable (X) to derive a power function ratio (Y/Xb) that is allegedly size-independent. The current consensus is that an estimate of fat-free mass (FFM) provides the most appropriate body size variable. In the scaling literature allometric modelling procedures have generally yielded FFM exponents (b) consistent with the theory of geometric similarity. We suggest that cardiac dimension data should be scaled by appropriate powers of FFM, derived from allometric modelling. However, despite the potential superiority of FFM as a scaling denominator, reference standards for normality based on FFM have not been developed or proposed. Future research should examine the robustness of the FFM-cardiac dimension relationship in large samples.

OBJECTIVES/OBJECTIVE:To evaluate the spectrum of electrocardiographic (ECG) changes in 1000 junior (18 or under) elite athletes. METHODS:A total of 1000 (73% male) junior elite athletes (mean (SD) age 15.7 (1.4) years (range 14-18); mean (SD) body surface area 1.73 (0.17) m2 (range 1.09-2.25)) and 300 non-athletic controls matched for gender, age, and body surface area had a 12 lead ECG examination. RESULTS:Athletes had a significantly higher prevalence of sinus bradycardia (80% v 19%; p<0.0001) and sinus arrhythmia (52% v 9%; p<0.0001) than non-athletes. The PR interval, QRS, and QT duration were more prolonged in athletes than non-athletes (153 (20) v 140 (18) milliseconds (p<0.0001), 92 (12) v 89 (7) milliseconds (p<0.0001), and 391 (27) v 379 (29) milliseconds (p = 0.002) respectively). The Sokolow voltage criterion for left ventricular hypertrophy (LVH) and the Romhilt-Estes points score for LVH was more common in athletes (45% v 23% (p<0.0001) and 10% v 0% (p<0.0001) respectively), as were criteria for left and right atrial enlargement (14% v 1.2% and 16% v 2% respectively). None of the athletes with voltage criteria for LVH had left axis deviation, ST segment depression, deep T wave inversion, or pathological Q waves. ST segment elevation was more common in athletes than non-athletes (43% v 24%; p<0.0001). Minor T wave inversion (less than -0.2 mV) in V2 and V3 was present in 4% of athletes and non-athletes. Minor T wave inversion elsewhere was absent in non-athletes and present in 0.4% of athletes. CONCLUSIONS:ECG changes in junior elite athletes are not dissimilar to those in senior athletes. Isolated Sokolow voltage criterion for LVH is common; however, associated abnormalities that indicate pathological hypertrophy are absent. Minor T wave inversions in leads other than V2 and V3 may be present in athletes and non-athletes less than 16 but should be an indication for further investigation in older athletes.

PURPOSE/OBJECTIVE:The purpose of the present investigation was to examine differences that may exist in maximal and submaximal exercise gas exchange parameters and their use in differentiating pathological and physiological left ventricular hypertrophy. METHODS:Exercise gas exchange responses were measured on-line during a maximal ramping cycle-ergometer exercise test in 10 young, male hypertrophic cardiomyopathy (HCM) patients, 11 elite triathletes, and 9 normal controls. RESULTS:The HCM patients exhibited significantly lower VO2max, anaerobic threshold (AT) in both absolute terms (ATVO2) and as a percentage of VO2max (AT%VO2max), and oxygen-pulse (O2-pulse) compared with triathletes and normal controls. Elite triathletes exhibited significantly increased VO2max, %VO2max, ATVO2, AT%VO2max and O2-pulse compared with controls. The VE/VCO2 at AT was significantly increased in the HCM patients compared with triathletes and controls, whereas no difference was observed between triathletes and controls. CONCLUSIONS:Maximal and submaximal exercise gas exchange responses may be used as an additional noninvasive tool in the differential diagnosis of physiologic and pathologic left ventricular hypertrophy.

Early echocardiographic studies of left ventricular (LV) morphology and function focused on single discipline athletes, primarily endurance and strength trained. To date there are few studies examining multi-disciplinary trained athletes. The present echocardiographic study examined LV morphology and function in 18 elite triathletes (swimming, cycling, and running) and 11 elite modern pentathletes (running, swimming, shooting, fencing, and show-jumping) compared with age- and sex-matched controls. Elite triathletes demonstrated significantly (p < 0.05) increased LV wall thickness and cavity dimensions together with LV mass, both in absolute terms and scaled for body surface area, compared with controls. Elite modern pentathletes demonstrated significantly (p < 0.05) increased LV wall thickness with a non-significant increase in LV internal diameter. Despite significant LV enlargement, the distribution of hypertrophy and diastolic filling indices were normal in both triathletes and modern pentathletes and significantly increased in the triathletes. It is concluded that multi-disciplinary training results in variations in LV morphology. The inciting stimulus resulting in LV enlargement in triathletes is associated with prolonged endurance activity, together with an isometric component accompanying cycling. In contrast, elite modern pentathletes experience a reduced endurance component combined with a high isometric component associated with fencing.

OBJECTIVE:To assess cardiac structure and function in elite cross-trained male and female athletes (Alpine skiers). METHODS:Sixteen athletes (10 male, six female) and 19 healthy sedentary control subjects (12 male, seven female) volunteered to take part in the study. Basic anthropometry determined height, body mass, body surface area, and fat free mass. Cardiac dimensions and function were determined by two dimensional, M mode, and Doppler echocardiography. Absolute data and data corrected for body size (allometrically determined) were compared by two way analysis of variance and post hoc Scheffé tests. RESULTS:Absolute left ventricular internal dimension in diastole (LVIDd), septal and posterior wall thickness and left ventricular mass were larger in athletes than controls (p < 0.05) and also increased in the men (p < 0.05) compared with women (except for septal thickness in controls). An increased LVIDd, septal thickness, posterior wall thickness, and left ventricular mass in athletes persisted after correction for body size except when LVIDd was scaled by fat free mass. Cardiac dimensions did not differ between the sexes after correction for body size. All functional indices were similar between groups. CONCLUSION/CONCLUSIONS:There is evidence of both left ventricular chamber dilatation and wall enlargement in cross trained athletes compared with controls. Differences in absolute cardiac dimensions between the sexes were primarily due to greater body dimensions in the men.