When sitting or standing quietly, the soleus muscles in the lower legs are the primary pumps which return pooled fluids from the lower body back to the heart. The critically important role the soleus muscles play in returning blood and interstitial fluid (lymphatic fluid) back to the heart has resulted in these muscles commonly being called our “second hearts”.



In the absence of adequate soleus muscle pumping, there will be insufficient fluid returning to the heart and so the heart will be unable to maintain normal blood pressure or sufficient output to sustain the tissues of the body. The result will not only be swollen feet, ankles and lower legs, but also varicose veins, achy muscles and joints due to excess fluid build-up. More importantly, decreased blood flow to the brain can lead to fatigue, migraine headaches, dizziness, blurry vision and cognitive dysfunction.

HeartPartner-1 was introduced by Sonostics to address soleus muscle insufficiency and the health complications associated with poor venous return to the heart, and correspondingly, low cardiac output when a person is upright (sitting or standing). HeartPartner provides a safe, easy to use, and relatively inexpensive solution to the challenge of ensuring adequate venous return to the heart.

HeartPartner provides a micromechanical stimulation to the plantar surface (sole) of the foot in order to activate specific receptors in the skin (Meissner’s Corpuscles). These receptors initiate a reflex response in the neuro-muscular system of the leg, resulting in contraction of the soleus muscles. In order to prevent fatigue of the soleus muscles, HeartPartner operates as a pacemaker, separating brief periods of stimulation with a relaxation phase which allows time for the soleus muscles to both refill with fluid, and recover from the previous contraction phase. HeartPartner is able to increase resting cardiac output by more than 30%, resulting in normalization of blood pressure in those with postural hypotension.

More information on the HeartPartner and the health conditions which the HeartPartner can help address can be found at the HeartPartner Store.


Sonostics Heart Parnter-MSonostic’s next generation HeartPartner incorporates a fundamentally different technology from the HeartPartner-1. Rather than utilizing micromechanical stimulation, the HeartPartner-M relies on dynamic magnetic fields to directly modulate plantar nerve activity, bypassing the Meissner’s Corpuscles. This technology provides both more effective soleus muscle stimulation and a more convenient user experience.

The magnetic neuro-modulation (Neurmod®) technology also sets the stage for developing devices for the international market, as well as the development of fully portable devices for applications where the user does not have continuous access to electrical line power. Market release of the HeartPartner-M model is expected in early 2026.