Intraaortic balloon pump

The intra-aortic balloon pump (IABP) is an invasive device utilized to increase cardiac output and myocardial perfusion. The IABP consists of a balloon which is connected to a long catheter. The catheter is inserted via the femoral artery and positioned such that the balloon sits in the descending thoracic aorta (Fig. 8.6). The balloon is also connected to a pump that allows it to be inflated and deflated at designated intervals.

The pump is synchronized with the electrocardiogram (ECG) so that the balloon is deflated in systole and inflated in diastole. When the heart ejects in systole, rapid deflation of the balloon creates an 'empty space' in the aorta, thus decreasing afterload and hence myocardial work. This improves cardiac contractility and output. During diastole, inflation of the balloon displaces a volume of blood equal to the volume of the balloon. Some of the blood will be pushed 'forward' and by this means the output of the heart is further augmented. As coronary blood flow occurs largely during diastole, inflation of the balloon during diastole also displaces blood 'backward' and thus enhances coronary blood flow.

Use of the IABP is indicated in selected cases of cardio-genic shock. It is particularly used for support of cardiac failure after coronary artery bypass graft (CABG) and as to a bridge to intervention for patients with acute coronary syndromes, mitral regurgitation, or septal defects. The device is not useful at very rapid heart rates (>150 bpm), since there is insufficient time for inflation and deflation of the balloon. It is contraindicated in aortic regurgitation as it exacerbates valvular insufficiency and heart failure. The IABP is also not useful in children because of their relatively rapid heart rates and because the major vessels in children are more distensible than in adults; inflation of the balloon in diastole simply distends the aorta without augmenting flow.

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