More than 40 years of ground-based photometric observations of the \delta Sct star 4 CVn revealed 18 independent oscillation frequencies , including radial as well as non-radial p-modes of low spherical degree \ell \leq 2 . From 2008 to 2011 , more than 2000 spectra were obtained at the 2.1-m Otto-Struve telescope at the McDonald Observatory . We present the analysis of the line-profile variations , based on the Fourier-parameter fit method , detected in the absorption lines of 4 CVn , which carry clear signatures of the pulsations . From a non-sinusoidal , periodic variation of the radial velocities , we discovered that 4 CVn is an eccentric binary system , with an orbital period P _ { orb } = 124.44 \pm 0.03 ~ { } d and an eccentricity e = 0.311 \pm 0.003 . We firmly detect 20 oscillation frequencies , 9 of which are previously unseen in photometric data , and attempt mode identification for the two dominant modes , f _ { 1 } = 7.3764 ~ { } \mathrm { d } ^ { -1 } and f _ { 2 } = 5.8496 ~ { } \mathrm { d } ^ { -1 } , and determine the prograde or retrograde nature of 7 of the modes . The projected rotational velocity of the star , v _ { eq } \sin i \simeq 106.7 ~ { } \mathrm { km s } ^ { -1 } , translates to a rotation rate of v _ { eq } / v _ { crit } \geq 33 \% . This relatively high rotation rate hampers unique mode identification , since higher-order effects of rotation are not included in the current methodology . We conclude that , in order to achieve unambiguous mode identification for 4 CVn , a complete description of rotation and the use of blended lines have to be included in mode-identification techniques .