Table 2.

Electrical stability of heart preparations

	Interval, s
	R-R	P-R	QRS	Q-T
Working heart
Start of protocol	0.422 ± 0.029	0.078 ± 0.010	0.045 ± 0.002	0.180 ± 0.017
End of protocol	0.412 ± 0.005	0.078 ± 0.022	0.046 ± 0.001	0.158 ± 0.024
Langendorff
Start of protocol	0.403 ± 0.054	0.071 ± 0.014	0.044 ± 0.012	0.177 ± 0.005
End of protocol	0.404 ± 0.056	0.066 ± 0.011	0.034 ± 0.002	0.175 ± 0.025
Blebbistatin
Start of protocol	0.438 ± 0.113	0.072 ± 0.010	0.032 ± 0.000	0.167 ± 0.017
End of protocol	0.469 ± 0.236	0.065 ± 0.025	0.031 ± 0.001	0.166 ± 0.009
In vivo data (Kour et al. 2013)	0.240–0.359	0.040–0.080	0.040–0.120	0.080–0.160

Values are means ± SD; n = 2. ECG parameters (R-R interval, P-R interval, QRS interval, and Q-T interval) for working, Langendorff, and mechanically arrested hearts are compared at the beginning and at the end of pacing protocols. In vivo values are also included for comparison.