Efficacy of a sound wave vibration intervention on heart rate and blood pressure.

The Sympara Therapeutic System (STS) device is a non invasive device worn as a necklace across the front of the neck with adherent pads to both clavicles which delivers therapeutic acoustic energy (sound waves). These sound waves are conducted via the clavicle to the nerves in the neck, shoulders, and armpit. We are investigating whether this device will decrease blood pressure and heart rate. The acoustic parameters of the sound waves/vibrations are proprietary and therefore amplitude, frequency and modulation are unknown to the investigators. The testing protocol consists of the subjects undergoing standardized autonomic reflex testing in order to evaluate the sympathetic and cardiovagal function. All experiments will be conducted in a dimly lit thermoneutral laboratory (22 degree -25 degree Centigrade). Prior to any testing, subjects will be connected to a 3-lead ECG to monitor HR, a finger blood pressure cuff and a pneumotrace to monitor respiratory movement continuous throughout the testing protocol. Subjects will perform a Valsalva maneuver, static handgrip test and cold pressor test at baseline (following 10 min of rest in a supine position). The STS device will then be applied to the subject for approximately 120 minutes, during the last 20 minutes of which the subject will repeat the testing protocol. The STS device will then be removed and the subject will rest in a supine position for an additional 20 minutes, followed by a final round of the testing protocol. Between the testing procedures (approximately 100 minutes) subjects will remain in a relaxed reclined position in the testing room. Descriptions of the tests are below: 1. Valsalva Maneuver: Subjects will be asked to forcefully exhale with an open glottis into a mouthpiece connected to the mercury column of a sphygmomanometer with an air leak. A 40-50 mmHg pressure is maintained for 15 seconds. 2. Static Handgrip Test: Subjects will be asked to squeeze a hand dynamometer with their maximal force. The highest force attained from three attempts will be considered the subject’s maximum voluntary contraction (MVC). The subjects will perform the static handgrip test by squeezing the hand dynamometer at 30% of MVC in a sustained manner for 3 min. The subject will be instructed to avoid inadvertent Valsalva maneuvers and to maintain normal breathing patterns during this test. 3. Cold Pressor Test: Subjects will submerge their entire hand (up to the wrist) in ice-cold water for 1 min. The temperature of the water will be maintained at approximately 0–1 degrees C. The subject will be instructed to avoid inadvertent Valsalva maneuvers and to maintain normal breathing patterns during this test. The testing protocol will take approximately four hours to complete. Subjects will be exited from the study following the completion of the testing protocol. The test will be performed in the order Valsalva, Hand grip then cold pressor. In the control group an identical procedure will be employed without the device activated. All testing will be supervised by specific research scientists with medical backup if required. The protocol will be identical in the three specified groups, namely healthy controls, healthy individuals with known elevated sympathetic activity and otherwise healthy individuals with early to mild hypertension.