Piras, F
Schiff, M
Chiapponi, C
Bossù, P
Mühlenhoff, M
Caltagirone, C
Gerardy-Schahn, R
Hildebrandt, H
Spalletta, G
Article History
Received: 4 June 2015
Revised: 24 July 2015
Accepted: 19 August 2015
First Online: 13 October 2015
Competing interests
: The authors declare no conflict of interest.