Definition & Overview
An American cardiac surgeon, named Dr. Adrian Kantrowitz, is the first to introduce the use of intra-aortic balloon assist device or pump in the 1960s. The primary role of this device is to increase coronary perfusion. This means to increase the flow of oxygen-rich blood in the heart so that the heart can fully perform its daily function. The device also helps pump blood when the heart is resting.
The word “coronary” refers to the arteries that surround and supply the heart with blood. Cardiac output, on the other hand, refers to the amount of blood the heart can pump in a minute.
The intra-aortic balloon assist device is meant to increase the cardiac output. An increased in cardiac output could increase blood flow to the heart specifically to the heart muscle. The heart supplies oxygenated blood to all the muscles in the body including its own tissues.
The intra-aortic balloon assist device is a cylindrical polyethylene balloon that is installed in the aorta (the largest artery in the body). The device is situated approximately two centimetres from the subclavian artery and assists the heart by counterpulsating.
Counterpulsation is a medical technique where the action of an external device is synchronised with the heart’s pump cycle so that the heart is not overworked. However, synchrony does not mean that they both work together in one beat. Instead, the device works when the heart is not pumping or in its resting phase. This helps deliver more blood to other parts of the body and increase oxygen supply.
The device is programmed so that it activates, pumps, and inflates the balloon when the heart is resting with the use of helium gas. Helium is a preferred gas because of its low viscosity (thick, sticky, and semi-fluid) and it does not cause embolism or blockage to the arteries and veins.
In cases where the balloon ruptured, the helium gas that leaks does not cause harm to the body as it is easily absorbed by the tissues around it and eventually dissolves.
The installation of intra-aortic balloon pump is performed using a minimally invasive method. It is done percutaneously or through the skin and does not require opening the chest.
The device is inserted through the femoral artery (found in the leg). The balloon is then advanced to the aorta with the use of a catheter.
Who Should Undergo and Expected Results?
Intra-aortic balloon assist device is indicated for people who are suffering from mitral valve regurgitation or chronic heart failure. The use of the device is only temporary and it can be removed once the patient’s cardiac output has stabilised. This can be between a couple of hours and a few days.
If the patient’s condition does not improve, surgeons may need to use other forms of treatment, such as valve surgery or the installation of a left ventricular assist device (LVAD).
Having this device installed in the body can cause extreme inconvenience because patients will be required to be still as much as possible in the hospital bed. This ensures that the device won’t get dislocated and puncture or injure nearby tissues or organs.
As soon as the pump is removed, the patient can go home and resume normal activities. If patients want to engage in intense physical activities, such as sports, they are required to consult their surgeons first.
How is the Procedure Performed?
The installation of an intra-aortic balloon pump is fairly simple. A flexible tube (catheter) is inserted through the femoral artery in the groin. The balloon on the catheter is guided all the way through the aorta using a special x-ray machine.
The device is connected to a computer that controls the catheter and the pump as well as the overall inflation and deflation of the balloon. The patient will feel the sensation of the balloon as it inflates and deflates.
Recovery can take a few days. The pump is normally used for a few hours or days. However, in some cases, it can be used for a month. As long as the device is inside the body, the patient must remain connected to the computer monitor.
The inflation of the balloon can be triggered based on the patient’s blood pressure, the results of their electrocardiogram, and if they have a pacemaker installed in their chest. A pre-set internal rate can also trigger the balloon to inflate.
The removal of the pump follows a simple process as well. First, the patient has to stop taking anticoagulant drug and surgeons have to confirm that activated clotting time (ACT) is less than 180 seconds.
The patient is conscious during the procedure and is administered with mild narcotic or analgesic agent that makes the procedure painless. Sutures are then removed and the drive console is turned off. The pump’s balloon is deflated by aspiration using a 20ml syringe, which is attached to the balloon’s inflation port.
Surgeons will let the access area (the artery where the catheter is inserted) bleed to remove any blood clots that have developed during the procedure. Pulse is observed to make sure that it is stable. When all components of the device have been removed, the patient will lie on their back for a few hours (minimum 6 hours) to avoid any bleeding or vascular complications.
Possible Risks and Complications
The installation of an intra-aortic balloon pump can cause systemic ischemia or restriction of blood supply to some tissues. This can cause a shortage of oxygen to key organs of the body as well as glucose. Glucose, which is transported by blood, is an important nutrient needed for cellular function or metabolism that helps keep tissues alive.
Another possible complication is compartment syndrome where pressure builds up in one of the body’s compartments where nerves and muscles are present. This usually manifests in the arms and legs. This occurs when the site of insertion of the catheter, which is the femoral artery, gets blocked or obstructed. The positioning of the balloon could also inhibit function to the renal artery and can cause subsequent kidney failure.
Cerebral embolism is also a possible complication as well as infections that can affect certain arteries such as the aorta and the iliac artery. Injury to the arteries can also happen if they are accidentally pierced.
The failure of the machine is also another problem. Its removal requires vascular surgery. If the machine is used longer than prescribed, the balloon can overinflate and it can tear the arterial walls in the aorta.
Texas Heart Institute; “Intra-aortic Balloon Pump”; http://www.texasheart.org/Research/Devices/iabp.cfm
Rjmatthewsmd; Intra Aortic Balloon Pump (IABP) Counterpulsation; http://www.rjmatthewsmd.com/Definitions/IABP_Counterpulsation.htm
Darmouth-Hitchcock; “Intra-aortic Balloon Pump Insertion”; http://www.dartmouth-hitchcock.org/heartvascular/treatmentsballoon.html#involve