Intra-aortic balloon pump

The Intra-aortic balloon pump (IABP) is a mechanical device that is used to decrease myocardial oxygen demand while at the same time increasing cardiac output. By increasing cardiac output it also increases coronary blood flow and therefore myocardial oxygen delivery. It consists of a cylindrical balloon that sits in the aorta and counterpulsates. That is, it actively deflates in systole increasing forward blood flow by reducing afterload, and actively inflates in diastole increasing blood flow to the coronary arteries. ^{[1] [2] [3]} The balloon is inflated during diastole by a computer controlled, ECG linked mechanism. This controls the flow of helium from a cylinder into and out of the balloon. Helium is used because its low viscosity allows it to travel quickly through the long connecting tubes.

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History

The IABP device was pioneered at the Cleveland Clinic during the early 1960s by Moulopoulus et al.^[2]

Use of counterpulsation

Intraaortic balloon counterpulsation is used in situations when the heart's own cardiac output is insufficient to meet the oxygenation demands of the body. These situations could include cardiogenic shock, severe septic shock, post cardiac surgery and numerous other situations.

Indications

The following situations may benefit from this device.^{[1] [2] [3]}

• Cardiogenic shock when used alone as treatment for myocardial infarction 9-22% survive the first year.
• Reversible intracardial mechanical defects complicating infarction, i.e. acute mitral regurgitation and septal perforation.
• Unstable angina pectoris benefits from counterpulsation.
• Post cardiothoracic surgery most common and useful is the use of counterpulsation in weaning patients from cardiopulmonary bypass after continued perioperative injury to myocardial tissue.
• Preoperative use has been suggested for high-risk patients such as those with unstable angina with stenosis greater than 70% of main coronary artery, in ventricaular dysfunction with an ejection fraction less than 35%.
• Bridge to heart transplant for those patients with left ventricular failure.
• Percutaneous coronary angioplasty

Contraindications

Absolute contraindication

The following conditions will always exclude patients for treatment:^{[1] [2] [3]}

• Aortic valve insufficiency
• Aortic dissection
• Severe aortoiliac occlusive disease

Relative contraindication

The following conditions could, under very pressing circumstances, be allowed to be included for therapy:^[1]

• Prosthetic vascular grafts in the aorta
• Aortic aneurysm
• Aortofemoral grafts

Complications

Since the device is placed in the femoral artery and aorta it could provoke ischemia, and compartment syndrome. At highest risk is the leg which is supplied by the femoral artery may become ischemic, but also placing the balloon too distal from the arcus aortae may induce occlusion of the renal artery and subsequent renal failure. Other possible complications are cerebral embolism during insertion, infection, dissection of the aorta or iliac artery, perforation of the artery and hemorrhage in the mediastinum. Mechanical failure of the balloon itself is also a risk which entails vascular surgery to remove under that circumstance. After balloon removal there is also a risk of 'embolic shower' from micro clots that have formed on the surface of the balloon, and can lead to peripherial thrombosis, myocardial ischemia, hemodynamic decompensation, and late pseudoaneurysm. ^{[1] [2] [3]}

Trivia

The IABP's developers thought that private insurance companies would not stand for such a radical new therapy, and approached the military, asking them to keep an eye out for IABP candidates in military hospitals. One day, the call came. A retired general was hospitalized in Walter Reed Army Medical Center. He had a history of multiple infarcts and was now end-stage. The IABP scientists were all ready to go, until they found out the general was former President Dwight D. Eisenhower. They declined the opportunity because they worried that if the IABP failed in him, it would permanently ruin the future prospects of the device.^{[citation needed]}

See also

• Cardiogenic shock
• Ventricular assist device

References

1. ^ ^{a b c d e} Intensive Care Medicine by Irwin and Rippe
2. ^ ^{a b c d e} Intra Aortic Balloon Pump (IABP) Counterpulsation mirror with better quality by P. J Overwalder, M.D., Department of Surgery, Division of Cardiac Surgery, University Hospital Graz, The Internet Journal of Thoracic and Cardiovascular Surgery. 1999. Volume 2 Number 2.
3. ^ ^{a b c d} Intra-aortic balloon pumping Department of Anaesthesia and Intensive Care of The Chinese University of Hong Kong