They measure sympathetic outflow in a much more defined manner than HRV here.  I rarely use electroacupuncture on the arm for hypertension.  Maybe I’ll give it a go and see how the patient and data respond!

Zhen Ci Yan Jiu. 2016 Apr;41(2):144-9.

[Electroacupuncture of “Quchi” (LI 11) Inhibits the Elevation of Arterial Blood Pressure and Abnormal Sympathetic Nerve Activity in Hypertension Rats].
Tan YY, Wang YY, Zhang Q.
Abstract
OBJECTIVE:
To observe the effect of electroacupuncture (EA) stimulation of “Quchi” (LI 11) on arterial blood pressure (BP), sympathetic nerve activity, barorefiex sensitivity (BRS) and expression of brain derived neurotrophic factor (BDNF) and nicotinamide adenine dinucleotide phosphate (NADPH) enzyme subunit p 47 phox in the rostral ventrolateral medulla (RVML) in hypertension rats.
METHODS:
A total of 45 male SD rats were randomly divided into sham operation, artificial cerebro-spinal fluid (aCSF) , model, “Quchi”(LI 11), and Jianyu (LI 15) groups (n = 9 in each group). The hypertension model was established by microinjection of Ang II (200 pg x kg(-1) x day(-1)) into the lateral ventricle (A-C: 1.0 mm, L: 1.4 mm, H: 4.5 mm) for 2 weeks (aCSF for aCSF group). After 1 week’s Ang II perfusion, EA (2 Hz/15 Hz, 1 mA) was applied to bilateral “Quchi” (LI 11)or “Jianyu” (LI 15) for 20 min, once daily for two weeks. The mean arterial pressure (MAP) and heart rate (HR) were detected by using a Non-Invasive Blood Pressure System (tail cuff method). The BRS (BP-to-HR transfer function) was determined by calculating the ratio of HR fluctuation (HR : HR, between post- and pre-intravenous injection of phenylephrine)/MAP fluctuation (MAP : MAP, between post- and pre-phenylephrine injection) , the urinary norepinephrine (NE) level in 24 h was assayed by ELISA. Real-time PCR and Western blot were used to detect the mRNA and protein expression of BDNF and p 47phox in the RVML region tissue.
RESULTS:
Following modeling, the MAP, HR and 24 h-urinary NE levels and p 47phox mRNA and protein expression levels in the RVML were significantly increased (P<0.01), and the BRS was decreased significantly (P<0.01). After EA intervention, the MAP, HR and 24 h-urinary NE levels and p 47 phox mRNA and protein expression levels in the RVML were considerably lower in the LI 11 group than in the model group (P<0.05), while the BRS level was markedly increased in the LI 11 group compared with the model group (P<0.05). The expression levels of BDNF mRNA and protein in the RVLM region were obviously up-regulated in the LI 11 group compared with the model group (P<0.05). No significant differences were found between the LI 15 group and the model group in the MAP, HR, 24 h-urinary NE, BRS, BDNF mRNA and protein and p 47 phox mRNA and protein expression levels (P>0.05).
CONCLUSION:
EA stimulation of “Quchi” (LI 11) can down-regulate arterial blood pressure, sympathetic nerve activity, and increase the baroreflex sensitivity in hypertension rats, which may be related to its effects in down-regulating p 47 phox mRNA and protein expression in the RVML.