Table 2

Comparison of heart rate variability indices between subjects with a positive head up tilt test (HUT) during the passive phase of tilt and those in whom HUT was positive during isoprenaline infusion

		Positive passive HUT (n = 30)			Isoprenaline + HUT (n = 12)		p Value ^2-151
		Supine	5 Min HUT	End HUT		Supine	p Value ^2-151		5 Min HUT	End HUT
LF^PP (beats/min²)	6.6 (3.5)	7.4 (3.4)	7.6 (3.6)		6.7 (3.5)	7.4 (3.5)	7.7 (3.6)	NS
HF^PP (beats/min²)	2.8 (1.7)	2.8 (1.5)	2.8 (1.6)		2.7 (1.6)	2.7 (1.5)	2.8 (1.6)	NS
LF^PP/HF^PP	2.7 (1.6)	2.4 (1.3)	2.5 (1.2)		2.7 (1.5)	2.5 (1.3)	2.6 (1.2)	NS
LF^BA (beats/min²/Hz)	0.5 (0.3)	0.5 (0.3)	0.6 (0.3)		0.5 (0.3)	0.5 (0.3)	0.6 (0.3)	NS
HF^BA (beats/min²/Hz)	0.4 (0.2)	0.4 (0.3)	0.5 (0.3)		0.4 (0.2)	0.4 (0.3)	0.5 (0.3)	NS
LF^BA/HF^BA	1.3 (0.5)	1.2 (0.6)	1.3 (0.6)		1.3 (0.5)	1.2 (0.6)	1.3 (0.6)	NS

Values are mean (SD).
↵2-151 For comparison of supine and upright results between groups.
BA, bandwidth area; HF, high frequency (0.15 to 0.4 Hz); LF, low frequency (0.04 to 0.15 Hz); PP, power peak.