Introduction
The Intra-Aortic Balloon Pump (IABP) is one of the most commonly used temporary mechanical circulatory devices. The IABP is primarily used in the management of cardiogenic shock, acute myocardial infarction with mechanical complications, and severe heart failure whether post-cardiac surgery or in patients presenting with severe heart failure. The IABP has been in clinical use since the late 1960s and its use spans across cardiac care units and cardiothoracic surgery centers as a bridge to recovery, bridge to surgery, bridge to more advanced mechanical circulatory support, or bridge to heart transplantation.
What is an Intra-Aortic Balloon Pump?
An Intra-Aortic balloon pump is a mechanical device consisting of a long thin tube with a small balloon at the tip and a console that connects to the catheter and controls the inflation and deflation of the pump using helium gas. The IABP is inserted via the femoral artery and sometimes the axillary or subclavian artery into the aorta. The console is connected to the balloon and is set up in a way that allows it to inflate and deflate with each heartbeat.
The IABP is not a heart pump; unlike the Left Ventricular Assist Device (LVAD), the IABP does not directly pump blood out of the heart, instead, it increases blood flow and reduces the workload of the heart.
How does the IABP work?
The IABP works on the principle of counterpulsation. The IABP is inflated and deflated at specific times during the cardiac cycle. The IABP is inflated during diastole while it is deflated during systole.
Balloon Inflation
The IABP is inflated during diastole and this leads to a diversion of blood upwards to the coronary arteries and downwards to the lower limbs. The IABP leads to an increase in coronary artery perfusion resulting in an increase in oxygen delivery to the myocardium, an increase in brain perfusion, and an increase in kidney perfusion.
Balloon Deflation
The IABP is rapidly deflated just before systole. This leads to a decrease in afterload with a decrease in myocardial oxygen consumption, an increase in cardiac output, and a reduction in the workload of the failing heart. The increase in coronary blood flow and the decrease in the workload of the heart lead to an improvement in overall circulation which helps the heart to recover.
Physiological Benefits of IABP
The benefits of IABP include:
Increased coronary artery blood flow
Increased oxygen delivery to the myocardium.
Decreased cardiac workload
A decrease in the oxygen consumption of the myocardium.
Increase in cardiac output
Despite a relatively small increase in cardiac output of approximately 0.5 – 1 L/min, the physiological benefit of this is immense.
Increased organ perfusion
The increase in blood flow to the brain, kidneys, and other organs leads to increased oxygen delivery to these organs.
Decreased myocardial oxygen consumption
The decreased workload of the heart, as explained earlier, results in decreased oxygen consumption.
When is an IABP used?
An IABP is indicated in the management of cardiogenic shock, acute myocardial infarction with mechanical complications, high-risk percutaneous coronary intervention, cardiac surgery, refractory unstable angina, severe heart failure, bridge to heart transplantation, and mechanical complications of myocardial infarction.
How is the procedure performed?
The procedure is done in a cardiac catheterization lab or an operating room with local anesthetic. The procedure involves:
Puncture to the femoral artery
Insertion of the balloon into the aorta
Confirmation of balloon placement via x-ray
Connecting the balloon to the console and setting the appropriate timing to the patient’s heartbeat
Monitoring During IABP Therapy
The patient is monitored in an intensive care unit. Some of the routine monitoring that is done includes: Blood pressure, heart rate and rhythm, oxygen saturation, urinary catheterization, leg examination to check for adequate circulation, balloon timing, ECG, laboratory tests, and chest x-rays to confirm balloon position.
Complications of IABP Therapy
Some of the most common IABP therapy complications are:
Vascular complications
Limb ischemia and reduced leg blood flow are the most frequent vascular IABP-related complications. Other vascular complications associated with IABP use include arterial trauma, hemorrhage, balloon rupture, and helium gas leak. Malposition and infection are other vascular problems that can occur.
Limb ischemia can be prevented by limiting the duration of IABP therapy. Also, the presence of peripheral arterial disease, peripheral neuropathy, and prolonged IABP therapy increases the risk of limb ischemia. Another complication of IABP use is a stroke.
Thrombosis, Aortic injury, Contraindications of IABP Therapy, Severe aortic regurgitation, aortic dissection, peripheral arterial disease, coagulopathy, and large abdominal or thoracic aortic aneurysms are all contraindications for IABP insertion. Intra-aortic balloon pump insertion is contraindicated in patients with peripheral arterial disease. The rationale is that IABP decreases peripheral perfusion, thereby increasing the likelihood of limb ischemia. IABP insertion is contraindicated in patients with large abdominal or thoracic aortic aneurysms because the procedure can cause rupture of the aneurysm.
Advantages of IABP
IABP advantages include:
Minimally invasive
Fast and easy to insert
Improves coronary artery blood flow
Decreases myocardial oxygen consumption
Improves cardiac output
Common and widely available
A good bridge to recovery as well as a bridge to other forms of mechanical circulatory support
Fewer complications than other mechanical circulatory support devices
Limitations of IABP
The limitations of IABP include:
Only provides modest circulatory support
Only works when the patient has a functional heart rhythm
No benefit in patients with profound cardiogenic shock
Does not directly increase cardiac output
IABP versus other mechanical circulatory support devices
IABP Impella VA-ECMO
Support type Counterpulsation Micro-axial pump Heart and lung support
Cardiac output support Modest Moderate to high Very high
Supports oxygenation
Insertion Percutaneous Surgical/percutaneous
Typical use Cardiogenic shock, cardiac surgery Severe left ventricular failure Profound cardiogenic shock, cardiac arrest, severe respiratory failure
Weaning and Removal of Intra-Aortic Balloon Pump
Weaning from IABP is always stepped down gradually. In other words, the balloon assistance is reduced from every heartbeat to every second or third heartbeat. During the weaning process and when the patient meets all the criteria for IABP removal, the balloon is removed. The puncture site is then compressed to prevent bleeding and the patient is monitored for any complications following the procedure.
Recent Advances in IABP Therapy
There have been numerous recent IABP therapy advancements. Although the IABP has been around for several years, technological developments related to IABP therapeutics have occurred. Some of the recent innovations are related to the material used to make balloons, the console, and other procedures. However, it has been established that IABP therapy is still a critical bridge to more advanced forms of mechanical circulatory support. The intra-aortic balloon pump has been used as a bridge to percutaneous interventions and cardiac surgery.
Conclusion
The IABP is a temporay mechanical circulatory device that has been used in cardiology and cardiothoracic surgery for decades. The IABP increases coronary blood flow, decreases the workload of the heart, and, therefore, improves the overall hemodynamics of patients with severe heart failure or cardiogenic shock. While the IABP is not a cardiac replacement, it can be life-saving in the appropriate clinical setting and patient population. The success of IABP therapy depends on a careful patient selection as well as the experience of the operator and the care provided to the patient after IABP implantation.
