Intra aortic balloon pump (IABP)
The intra aortic balloon pump (IABP) is a device used in some critically ill people to help the heart pump. This temporary help may make the difference between life and death. The heart-lung machine used in open-heart surgery is a similar device, but
is too complicated to be used for conditions other than in surgery.
The basic components of the device are a catheter tipped with a 10-inch balloon and a pump machine that inflates the balloon with either helium or carbon dioxide. The balloon is inserted via a femoral artery cutdown and guided under fluoroscopic control to a position in the descending thoracic aorta just distal to the left subclavian artery. In some models, the balloon is tri-segmented. When inflation begins in a tri-segmented balloon, the middle segment is inflated first, then the distal ends inflate simultaneously; there is no occlusion of the aorta. An alternative type of balloon catheter consists of only one segment with a second small balloon just distal to the main one; the smaller balloon partially occludes the aorta only during diastole, thus providing directional flow.
The pump console contains signal processing, drive, and timing and control mechanisms for appropriate inflation and deflation. The system also contains a display and diagnostic unit. The physiologic effect of the IABP is to improve coronary blood flow and systemic circulation. It does this by augmenting aortic root pressure during ventricular diastole at the time of maximum blood flow, and reducing the workload of the heart by decreasing the amount of residual blood in the aortic arch, thereby decreasing resistance to the flow of blood from the ventricle. Inflation of the balloon during diastole just after aortic valve closure, and deflation just prior to ventricular systole reduces the pressure workload of the left ventricle and lessens oxygen demand and consumption by the myocardium. Timing of the inflation-deflation cycle is based on the arterial pulse wave configuration seen on the console's display screen. Adjustments to the cycle are made according to the site of arterial wave sampling, heart rate, and the depth of diastolic dip.
The IABP is sometimes used during cardiac surgery to help remove the patient from the heart-lung bypass machine. It may support a weakened heart in the recovery room after surgery. It is sometimes used to help the heart of severely ill people who are awaiting a cardiac transplant. It can be used to improve blood flow to the heart while you await surgery or angioplasty for severe blockage of the heart arteries. Cardiogenic shock, a serious complication of a severe heart attack, occurs when the heart cannot pump well enough to keep blood pressure high enough for circulation of the blood. The IABP can improve the circulation until the person improves or has coronary angioplasty or bypass surgery.
The IABP is a long tube (catheter) with a collapsed, 8-inch, sausage-shaped plastic balloon at its tip. The catheter is inserted in an artery in your groin. You will be given a shot to numb the area where the tube is inserted, but you will remain awake. You may have some minor discomfort, but the procedure is mostly painless. The doctor directs the tube through the artery and positions it in your aorta, the large blood vessel in the mid-chest. A pump is attached to the hub end of the catheter. The balloon is rapidly inflated and deflated using your own heartbeat as a trigger.
The balloon inflates at the beginning of the resting period of each heartbeat. The inflated balloon raises blood pressure in the aorta while the heart muscle "catches its breath." The higher aortic blood pressure increases blood flow to all the body's organs, particularly to the resting heart muscle through the coronary arteries.
Rapid deflation of the balloon occurs with the start of the next heartbeat. This quickly lowers blood pressure in the aorta and lessens the work of the heart. The result is increased blood flow from the heart at less cost to the heart.