An LVAD (left ventricular assist device) is a small mechanical pump implanted inside the chest, connected by a thin cable that exits through the skin of the abdomen to an external controller and battery pack worn on the body. From the outside, the most visible parts are the cable emerging from the belly, a small controller unit, and two battery packs, all of which can be carried in a vest, shoulder bag, or specially designed shirt under clothing.
The Internal Pump
The pump itself sits inside the chest, so you’ll never see it on an LVAD patient. But understanding its size helps explain why the surgery is feasible. The most widely used model, the HeartMate 3, is a centrifugal pump roughly the size of a small tangerine. It occupies about one-third the volume of the original HeartMate I from the 1990s. The pump is placed in the pericardial space, the natural sac surrounding the heart, so it doesn’t require a separate pocket carved into the abdomen like older models did.
Inside, the pump uses a magnetically levitated rotor, meaning the spinning component floats without touching any surfaces. There are no bearings or mechanical contact points to wear down. The rotor is surrounded by electromagnetic coils that both spin it and keep it suspended. This design makes the pump quieter and more durable than earlier versions. Some patients and people standing close to them can hear a faint, steady hum.
Two internal tubes connect the pump to the heart and the circulatory system. An inflow tube, called a cannula, is sewn into the left ventricle (the heart’s main pumping chamber) and draws blood into the device. An outflow tube carries that blood from the pump and delivers it into the aorta, the body’s largest artery. These tubes are made of flexible, reinforced material and are typically covered in a woven fabric that encourages tissue to grow around them, anchoring them in place over time.
The Driveline Cable
The driveline is the part that makes an LVAD visible from the outside. It’s a flexible cable, roughly the diameter of a finger, that runs from the internal pump through the abdominal wall and out through a small opening in the skin, usually on the right side of the belly. This cable carries electrical power to the pump and sends data back to the controller.
The outer layer of the driveline is a silicone sheath, which gives it a smooth, rubbery appearance. Inside that sheath are color-coded wires. The cable has some slack so patients can move, bend, and twist without pulling on the exit point. Where it leaves the body, the driveline is anchored and dressed with a bandage to prevent infection and keep the cable from shifting.
What the Exit Site Looks Like
The spot where the driveline exits the skin is one of the most carefully maintained parts of the whole system. It looks like a small, round wound site, typically covered by a layered dressing. In most care routines, the area is cleaned with an antiseptic solution and then covered with sterile gauze or a specialized foam sponge, followed by a transparent film dressing on top. Some protocols use silver-coated antimicrobial dressings to reduce infection risk.
The driveline is usually stabilized against the skin with tape or an abdominal securement band so it doesn’t tug or move. A common approach involves wrapping a small piece of cut gauze snugly around the cable where it meets the skin, then placing a sterile gauze pad over the entire area. The transparent film over everything keeps it sealed while still allowing visual inspection. Patients change this dressing regularly, often daily, as a core part of living with the device.
The Controller
The controller is the “brain” of the system. It’s a small, rectangular electronic unit, roughly the size of a smartphone but thicker and heavier. It has a digital display screen and a few buttons. The screen shows real-time information: how fast the pump’s rotor is spinning (in RPM), how much blood is flowing through the device (in liters per minute), and how much power the pump is using (in watts).
Colored indicator lights on the controller show the status of whatever power source is connected. A green light indicates wall or car adapter power. Two battery indicators, labeled “1” and “2,” show which battery is active and roughly how much charge remains in each. An alarm indicator light changes color depending on the severity of any issue, from low-priority alerts to urgent warnings. When an alarm triggers, the display switches from pump data to text instructions telling the patient what’s happening and what to do.
The controller has an alarm mute button that can silence low or medium alarms for five minutes, and a scroll button that lets patients cycle through active alarms and pump readings or brighten the screen. The whole unit connects to the driveline cable on one end and to two power sources on the other.
Batteries and Power Units
For mobility, patients carry two rechargeable battery packs. Each battery is a compact rectangular block, similar in size to a small portable phone charger but heavier. Both batteries plug into the controller, providing redundancy: if one fails, the other takes over. Together, the two batteries and the controller weigh several pounds, which is why carrying systems matter so much for comfort.
At home, patients can plug into a mobile power unit that connects to a standard electrical outlet. This small tabletop device provides continuous power, so patients don’t drain their batteries while resting or sleeping. It’s designed to be lightweight and portable enough to move from room to room or bring when traveling.
How Patients Carry the Equipment
From the outside, an LVAD patient may not look noticeably different from anyone else. The external components can be concealed in several ways, depending on personal preference.
- LVAD-specific shirts: These are lightweight, breathable undershirts with built-in Velcro pockets on each side for batteries and a separate pocket for the controller. They distribute the weight evenly across the torso and can be worn under regular clothing.
- Tactical holster shirts: Similar to shirts worn for concealed carry, these have two side pockets sized for batteries or battery clips. The controller hangs on a neck strap or clips to a belt. They come in crew neck or V-neck styles and multiple colors.
- Vests: Fishing, hunting, or photography vests have pockets large enough to hold the batteries and sometimes the controller. These work well in cooler weather or for patients who prefer not to wear a compression-style shirt.
- Shoulder bags and belt packs: Some patients use a messenger-style bag or a belt holster to carry everything externally, which makes swapping batteries easier on the go.
The driveline cable routes from the abdominal exit site up to wherever the controller is positioned, tucked under clothing. With the right carrying system, the only visible hint of the device is occasionally the slight bulk of the batteries or the outline of the controller under a shirt.