The Effect of Upright Posture on Left Atrial Strain in Competitive Athletes

BACKGROUND

Left atrial strain (LAS) assessment by speckle tracking echocardiography (STE) has been shown to be a remarkable means of quantifying LA function as an early marker of LV pathology. As exercise testing is also performed on a treadmill, the aim of this study was to investigate the effect of upright posture on LAS in healthy athletes.

METHODS

Fifty male athletes (mean age 25.7 ± 7.3 years) underwent transthoracic echocardiography (TTE) in the upright and left lateral positions. In addition to the conventional echocardiographic parameters, in all athletes, LA conduction strain (LAScd), contraction strain (LASct), reservoir strain (LASr), and maximum LA volume (LAVmax) were assessed by STE in both positions.

RESULTS

Comparing upright posture and the left lateral position, LAScd (-14.0 ± 5.9% vs. -27.4 ± 7.1%; p < 0.001), LASct (-4.6 ± 3.5% vs. -11.3 ± 4.1%; p < 0.001), LASr (18.7 ± 7.6% vs. 38.7 ± 8.0%; p < 0.001), and LAVmax (24.4 ± 8.8% vs. 50.0 ± 14.2%) differed significantly.

CONCLUSIONS

Upright posture has a significant effect on LA deformation, with decreased LAScd, LASct, and LASr. The results of this study contribute to the understanding of athletes' hearts and must be considered when performing echocardiography in healthy athletes on a treadmill.

Left ventricular diastolic function: Effects of high-intensity exercise after acute myocardial infarction

OBJECTIVES

Reduced left ventricular (LV) diastolic function indicates poor prognosis after acute myocardial infarction (AMI). Our aim was to study whether a twelve-week high-intensity interval training program could improve diastolic function in patients with a relatively recent AMI.

DESIGN

Twenty-eight patients (mean age 56 (SD 8) years) with a recent AMI performed high-intensity interval training twice a week for 12 weeks. Each training session consisted of four 4-minute bouts at 85%-95% of peak heart rate, separated by 4-minute active breaks. A cardiopulmonary exercise test was performed to determine peak oxygen uptake (VO_2peak ). Echocardiography was performed at rest and during an upright bicycle exercise test.

RESULTS

There was a significant increase in mitral annulus early diastolic velocity (e') at peak exercise (75 W) from baseline to follow-up (7.9 (1.5) vs. 8.4 (1.7) cm/s, P = .012), but no change in e' at rest (7.1 (1.9) vs. 7.3 (1.7) cm/s, P = .42). There was a significant increase in VO_2peak (mean (SD), 35.2 (7.3) vs. 38.9 (7.4) ml/kg/min, P < .001). e' at peak exercise correlated with VO_2peak both at baseline and follow-up (r = 0.50, P = .007, and r = 0.41, P = .032).

CONCLUSION

The present study shows that LV diastolic function during exercise is related to VO_2peak . We also found an improvement of diastolic function after exercise training, even in a population with a relatively well preserved systolic and diastolic function. The results demonstrate the importance of obtaining measurements during exercise when evaluating the effects of exercise interventions.

Orthostatic effects on echocardiographic measures of ventricular function

Orthostatic-induced alterations in Doppler echocardiographic measures of ventricular function have not been well-defined. Identifying such changes may provide useful insights regarding the responses of these measures to variations in ventricular loading conditions. Standard assessment of mitral inflow velocity and tissue Doppler imaging (TDI) of left ventricular longitudinal myocardial velocities was performed on 14 young males (mean age 17.9 ± 0.7 years) in the supine position and then 5 minutes after assuming a sitting position with legs dependent. Upon sitting, average values of stroke volume and cardiac output fell by 28% and 18%, respectively, while heart rate increased from 64 ± 10 to 73 ± 12 beats/min (+14%) and calculated systemic vascular resistance rose from 12.9 ± 2.2 to 16.4 ± 3.1 units (+27%). Mitral E peak velocity declined from 87 ± 16 to 64 ± 16 cm/sec, and average TDI-E' and TDI-S both decreased (by -44% and -20%, respectively). When adjusted for orthostatic decreases in left ventricular end-diastolic volume, the mean decrease in TDI-E' was reduced to -29 (P < 0.01), but no significant decline was observed in adjusted TDI-S. Average E/E' rose with sitting by 40% (P = 0.02). These findings suggest that (a) decreases in TDI measures when assuming the upright position reflect the reduction of left ventricular size; (b) orthostatic fall in TDI-E' is also related to smaller ventricular size but, in addition, to a nonspecified reduction in ventricular relaxation; and (c) values of E/E' do not reflect alterations in ventricular preload, which occur during an orthostatic challenge.