Methods
Pulsed Doppler tissue imaging in endurance athletes: relation between left ventricular preload and myocardial regional diastolic function

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Abstract

The aim of this study was to assess the effects of endurance training on myocardial regional systolic and diastolic function by pulsed Doppler tissue imaging (DTI). Twenty male water polo players and 20 male control subjects underwent standard Doppler echocardiography and pulsed DTI, performed in apical views by placing a sample volume on left ventricular (LV) basal septal and inferior walls. Age, body surface area, and blood pressure were comparable between the 2 groups, with lower heart rate in athletes (p <0.001). They had significantly increased LV mass index (due to both higher wall thickness and end-diastolic diameter), greater endocardial fractional shortening, higher transmitral early/atrial (E/A) peak velocities ratio. In athletes, DTI analysis showed significantly prolonged myocardial deceleration time and greater myocardial E/A peak velocity ratio of septal and inferior walls, whereas myocardial early peak velocity was increased (p <0.01) only at the inferior wall. In the overall group, we found univariate relations of septal and inferior E/A peak velocity ratio and myocardial deceleration time with LV mass levels, and, in particular, with the sum of wall thickness. By separate multivariate analyses, however, these relations disappeared, being dependent on heart rate degree. Another association found between LV end-diastolic diameter and myocardial early diastolic wave peak velocity of the inferior wall (r = 0.68, p <0.0001) remained significant (standardized β coefficient 0.60, p <0.00001), even after adjusting for heart rate, body surface area, age, and stroke volume (R2 = 0.71, p <0.00001). In conclusion, DTI is a useful tool for detecting regional changes in myocardial function induced by training, because athletes present with an improvement in diastolic passive properties of myocardium. The higher early diastolic velocity of the inferior wall and its relation to increased preload may represent an indicator of aerobic training, allowing quantification of the degree of LV adaptation to endurance exercise.

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Study group

We enrolled 20 highly competitive, male water polo players, who had been trained intensively 15 to 20 hours/week for >5 years, and 20 untrained healthy men. The training protocol included 3 hours/day of aerobic isotonic dynamic exercise at incremental workloads of 70% to 100% of maximal HR, and only 1-hour/week of isometric static exercise at 30% of maximal workload. Subjects were excluded for coronary artery disease, valvular and congenital heart disease, heart failure, cardiomyopathy,

Clinical characteristics of study group

The 2 groups were comparable for age (22.5 ± 5.3 years in controls and 19.7 ± 3.7 years in athletes), body surface area (BSA) (1.82 ± 0.15 and 1.86 ± 0.07 m2, respectively) and BP (125.1 ± 9.8/73.8 ± 7.2 and 115.0 ± 14.7/70.5 ± 5.6 mm Hg). As expected, HR was lower in the athletes (65.6 ± 3.9 vs 75.1 ± 9.4 beats/min, p <0.001).

Standard Doppler echocardiographic analysis (Table I)

Athletes had greater endocardial fractional shortening (p <0.05) and stroke volume (p <0.01), higher peak velocity E/A ratio (p <0.02), and greater LV mass index (p

Discussion

This study underscores the usefulness of DTI to identify myocardial diastolic properties of the trained heart. Endurance athletes have (1) greater inferior Em peak velocity than controls, (2) greater septal and inferior Em/Am ratio, and (3) longer myocardial DTm in both walls. Finally, and most important, in the overall population, the difference in Em/Am ratio and myocardial diastolic times are explained by HR changes, but Em peak velocity is directly and independently associated with LVIDD.

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