Table 2.

Cardiomyocyte structural maturation

Age range	Cardiomyocyte type	Key points	Citation
<0 weeks	Left and right ventricular	Structural development continues after birth Increase in cell size, elongation and contractile force. Increase in myofibril organization, density and width.	Kim et al. (1992)
<2 years	Left and right ventricular	Increase in SR formation, T-tubule formation and Z-band alignment	Wiegerinck et al. (2009)
<0–67 years	Left ventricular		Racca et al. (2016)
<0–68 years	Left atrial, right and left ventricular	Myosin heavy chain expression, kinetics change with age (tissue specific)	Reiser et al. (2001)
<0–81 years	Left and right atrial, left and right ventricular	Decrease in α-MHC. Increase in β-MHC. Increase in myosin enzymatic activity	Cummins and Lambert (1986)
0–80 years	Left ventricular		Schier and Adelstein (1982)
<0–11 years	Right ventricular	Myosin light chain isoform switching occurs during perinatal development	Elhamine et al. (2016)
<0–52 years	Atrial and ventricular	Increase in VLC-2.	Cummins et al. (1980)
<0–71 years	Left and right atrial, left and right ventricular	Increase in VLC-1. Decrease in ALC-1	Price et al. (1980)
<0–81 years	Right ventricular		Auckland et al. (1986)
< 1 year	Atrial	Myofilament isoform switching occurs during perinatal development	Bhavsar et al. (1991)
<1 year	Atrial		Sasse et al. (1993)
<0–11 years	Right ventricular	Decrease in number of cTnT isoforms. Decrease in ssTnI and cTnT1.	Elhamine et al. (2016)
0–35 years	Right atrial	Increase in cTnI and cTnT3	Saba et al. (1996)
0–58 years	Left ventricular		Anderson et al. (1991, 1995)
0-adult	Ventricular		Hunkeler et al. (1991)