High Voltage Galvanic Stimulation, or HVGS, is a type of electrotherapy used by physical therapists to manage a variety of conditions. It involves the application of a high-voltage, low-amperage direct current through electrodes placed on the skin. This specific current allows the therapy to affect deeper tissues without causing discomfort or harm to the patient. The primary purpose of this modality is to use electrical energy to influence physiological processes, such as healing and swelling, at the cellular level.
How HVGS Works on a Cellular Level
The effectiveness of High Voltage Galvanic Stimulation is rooted in its electrical waveform and its influence on cellular behavior. HVGS utilizes a twin-peak monophasic pulsed current, meaning the electricity is delivered in short, rapid bursts. This pulsed nature, combined with a high voltage of up to 500 volts, enables the electrical charge to overcome the skin’s natural resistance and penetrate deep into the underlying tissues.
Despite the high voltage, the overall amount of electricity, or amperage, is very low, which ensures the treatment is safe and comfortable for the patient. The core principle behind its therapeutic action is known as galvanotaxis, the process of attracting specific types of cells to an electrical field. All cells in the body possess an electrical charge, and applying an external current can direct their movement.
The polarity of the electrodes—whether they are negative (cathode) or positive (anode)—determines which cells are attracted to the treatment area. The negative electrode is particularly effective at attracting neutrophils, which are immune cells that clean debris from a wound site. It also promotes the development of granulation tissue, the new connective tissue and tiny blood vessels that form on the surfaces of a wound during the healing process.
Conversely, the positive electrode attracts macrophages, another type of immune cell that plays a part in the later stages of tissue repair and inflammation control. The anode is also thought to help inhibit bacterial growth. By strategically placing and alternating the polarity of the electrodes, a therapist can help guide the natural sequence of cellular events required for efficient tissue repair.
Common Uses in Physical Therapy
High Voltage Galvanic Stimulation is most frequently applied to accelerate the healing of damaged tissue. Its most prominent use is in the management of chronic skin wounds that are slow to heal on their own. This includes conditions such as diabetic foot ulcers and pressure sores. By promoting cellular migration and the formation of new tissue, HVGS can help facilitate closure of these persistent wounds.
Another primary application of HVGS is for the reduction of edema, or swelling. The electrical current helps disperse the excess fluid that accumulates in the tissues following trauma. The negative polarity is used in these cases to repel negatively charged proteins, helping to move them out of the injured area and into the lymphatic system for removal.
While wound healing and edema control are its main applications, HVGS is also used to a lesser extent for pain management and reducing muscle spasms. The stimulation can interfere with the transmission of pain signals to the brain, providing temporary relief. For muscle spasms, the current can be used to induce fatigue in the overactive muscle, causing it to relax. These uses are considered secondary to its effects on tissue repair.
What to Expect During a Treatment Session
A therapist prepares the treatment area by cleaning the skin to ensure good electrical conductivity. One or more “active” electrodes are then placed directly on or around the wound or injured site. A larger “dispersive” or “inactive” pad is placed on a nearby area of the body to complete the electrical circuit. This setup allows the current to flow through the targeted tissues.
Once the electrodes are secured, the therapist will slowly increase the intensity of the electrical current. Patients describe the sensation as a mild and non-painful tingling or buzzing at the site of the active electrodes. The intensity is adjusted to the patient’s comfort level, ensuring the stimulation is strong enough to be effective but not cause discomfort.
The duration of a treatment session can vary depending on the condition being treated. A session may last anywhere from 20 to 60 minutes. For chronic wound care, treatments may be administered several times per week to achieve the desired outcome.
Safety Considerations and Contraindications
When administered by a qualified professional, HVGS is a safe therapeutic modality. However, there are specific situations where its use is not recommended. These absolute contraindications include applying the current over areas with:
- A cardiac pacemaker
- A pregnant uterus
- The chest or over the carotid sinus in the neck
- Known cancerous lesions
Therapists also exercise caution when applying HVGS over areas where a patient has impaired or absent sensation, as they may not be able to provide accurate feedback on the current’s intensity. Caution is used over areas of skin that are damaged or have existing irritation to avoid exacerbating the issue. The most common side effect is minor skin irritation or redness under the electrodes, which resolves quickly after the treatment is completed.