Table 1.

Cardiac electrophysiological parameters of FA and SHS hearts ($\text{PCL}=150\text{\hspace{0.17em} ms}$).

Duration	4 wk		8 wk		12 wk
Exposure	FA ($n=4$)	SHS ($n=4$)	FA ($n=4$)	SHS ($n=4–5$)	FA ($n=4$)	SHS ($n=5$)
APD (ms)	$68.5\pm 5.3$	$66.3\pm 10.1$	$61.1\pm 7.6$	$60.7\pm 4.7$a	$61.1\pm 10.1$	$64.1\pm 7.8$
APDD (${\text{ms}/\mathrm{mm}}^2$)	$0.57\pm 0.12$	$0.48\pm 0.09$	$0.41\pm 0.09$	$0.28\pm 0.06$a	$0.43\pm 0.09$	$0.43\pm 0.07$
Trise (ms)	$3.5\pm 0.4$	$3.3\pm 0.2$	$3.9\pm 0.2$	$3.7\pm 0.1$a	$3.3\pm 0.2$	$3.6\pm 0.3$
CV (cm/sec)	$45.4\pm 2.6$	$48.0\pm 1.9$	$48.3\pm 1.1$	$47.3\pm 1.5$b	$49.5\pm 0.4$	$44.9\pm 1.8$
CaTD (ms)	$69.2\pm 2.2$	$65.8\pm 2.9$	$66.3\pm 1.0$	$63.9\pm 1.8$b	$67.2\pm 2.0$	$68.3\pm 2.2$
VT/VF incidence	0/4	0/4	0/4	0/5	0/4	0/5
Extra beats	$0.8\pm 0.5$	$1.5\pm 0.6$	$2.3\pm 1.1$	$2.6\pm 1.2$b	$2.5\pm 1.2$	$0.8\pm 0.5$

Note: Data were analyzed with two-way analysis of variance (ANOVA) with Tukey’s posthoc test. No statistical differences were observed between groups, among exposure duration, or with group/duration interaction. APD, action potential duration; APDD, action potential duration dispersion; CaTD, ${\mathrm{Ca}}^{2+}$ transient duration; CV, conduction velocity; FA, filtered air; PCL, pacing cycle length; SHS, secondhand smoke; Trise, action potential rise time; VF, ventricular fibrillation; VT, ventricular tachycardia. VT/VF incidence is shown as the ratio of hearts per group with VT/VF. Extra beats, the maximum number of extra beats observed in each heart during a complete S1–S2 pacing protocol.

^a$n=4/\text{group}$.

^b$n=5/\text{group}$.