Dilated inferior vena cava: A common echocardiographic finding in highly trained elite athletes

Typical structural features of the athlete's heart as defined by echocardio graphy have been extensively described; however, information concerning ext racardiac structures such as the inferior vena cava (IVC) is scarce. Fifty- eight top-level athletes and 30 healthy members of a matched control group underwent a complete Doppler echocardiographic study. IVC diameter was dete rmined in the subxiphoid approach 10 to 20 mm away from its junction to the right atrium. Measures reflect the median values between maximal inspirato ry and expiratory values. IVC respiratory collapsibility index was determin ed as welt IVC In athletes was 2.31 +/- 0.46 cm compared with 1.14 +/- 0.13 cm in the control group (P < .001). Swimmers had an IVC diameter of 2.66 /- 0.48 cm compared with 2.17 +/- 0.41 cm in other athletes (P < .05). The IVC was normal (<1.7 cm) in 5.2%, dilated (1.7 to 2.5 cm) in 70.7%, and ver y dilated (greater than or equal to 2.6 cm) in 24.1% of athletes. The colla psibility index was 58% +/- 6.4% in athletes compared with 70.2% +/- 4.9% i n the control group (P < .001). Correlation was found between IVC size and VO2 max (r = 0.81, P < .001) and the right ventricle (r = 0.81, P < .001) a nd with collapsibility index (r = -0.57, P < .05). Multiple regression anal ysis showed the impact of VO2 max, cardiac index, and right ventricular and left ventricular end-diastolic dimensions on IVC diameter. IVC dilatation probably represents adaptation of an extracardiac structure to chronic stre nuous exercise in top-level, elite athletes.