Low-frequency and low-intensity ultrasound increases cardiac parasympathetic neural activity and decreases clinic hypertension in elderly hypertensive subjects with type 2 diabetes.

BACKGROUND: The aims of the present study were to determine the effects of an ultrasound irradiation on clinic hypertension and the heart rate variability in elderly hypertensive subjects with type 2 diabetes. METHODS: We examined the effects of ultrasound (800 kHz, 25 mW/cm2) applied to the forearm for 10 min on the autonomic nerve activity and the difference between BP at home and at a clinic visit in Japanese subjects with type 2 diabetes and hypertension. RESULTS: In 108 subjects who displayed systolic BP (SBP) >140 mm Hg at a clinic visit, 75 subjects (69%) had a mean SBP <135 mm Hg at home and 33 subjects (31%) had a mean SBP >135 mm Hg at home in the morning for 14 days. SBP, pulse rate, and pulse pressure in the ultrasound treatment group were significantly lower than the baseline values in these hypertensive subjects with type 2 diabetes, and lower than those of placebo controls independently of SBP at home. In 31 subjects who displayed systolic BP >140 mm Hg at a clinic, standard deviation of all RR intervals and the root mean square of successive differences were significantly higher in the ultrasound treatment group than the baseline values in these hypertensive subjects with type 2 diabetes, and lower than those of placebo controls. CONCLUSIONS: The ultrasound treatment increases the cardiac parasympathetic neural activity and decreases the differences between SBP at home and at a clinic visit in elderly hypertensive subjects with type 2 diabetes.

Low-frequency and low-intensity ultrasound irradiation to the forearm improves an index of arterial stiffness in subjects with type 2 diabetes and hypertension.

OBJECTIVES: The arterial pressure-volume index (API) is a non-invasive assessment of arterial stiffness, and is suggested as a useful predictor of future cardiovascular events. The aim of the present study was to determine the effects of low-frequency and low-intensity ultrasound applied to the forearm for 10 min on the API in Japanese subjects with type 2 diabetes and hypertension. METHODS: We examined the effects of low-frequency and low-intensity ultrasound (800 kHz, 25 mW/cm2) applied to the forearm for 10 min on the API, blood pressure (BP) and pulse rate in 40 Japanese subjects (13 men and 27 women; mean age ± SE, 70 ± 2 years) with type 2 diabetes and hypertension, who had the API > 30 and systolic BP > 140 mmHg at a clinic visit. We also examined the effects of the ultrasound irradiation for 10 min on the API, BP and pulse rate in 33 Japanese subjects (11 men and 22 women; mean age ± SE, 65 ± 2 years) with type 2 diabetes and hypertension, who had the API > 30 and systolic BP (SBP) < 140 mmHg. RESULTS: The API, systolic BP and pulse rate in the ultrasound treatment group was significantly lower than the baseline values in the subjects who had the API > 30 and either the baseline of systolic BP > 140 mmHg or systolic BP < 140 mmHg. CONCLUSIONS: The low-frequency and low-intensity ultrasound irradiation to the forearm for 10 min might be useful as a preventive application for arterial stiffness in subjects with type 2 diabetes and hypertension.