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Anaphylactic or anaphylactoid reactions including protamine reactions,

Mechanical assist devices

Intra-aortic balloon pump

The IABP consists of a long cylindrical balloon placed at the end of a catheter placed in the descending thoracic aorta. The tip of the catheter should be positioned just distal to the left subclavian artery. The balloon should also be placed so that it does not occlude the renal or mesenteric arteries. Helium is pumped into the balloon to inflate it at the beginning of diastole. The balloon is deflated at the end of diastole. It has been described as the “ideal inotrope”. In the failing heart it can decrease myocardial workload while increasing coronary perfusion.

  1. “Augmentation.” By inflating at the beginning of diastole (just after the closure of the aortic valve), the aortic diastolic pressure is increased or “augmented”, thus improving coronary perfusion. Remember, left ventricular coronary flow occurs during diastole with the gradient to flow being the difference between the aortic diastolic pressure (ADP) and the right atrial pressure (RAP). That is CPP = ADP – RAP.
  2. “Diastolic decrement” .The balloon deflates just before cardiac systole (just before opening of the aortic valve). This leads to a sudden decrease in the aortic pressure and thus LV afterload.
  3. The IABP can be adjusted so that the balloon inflates and deflates with every cardiac cycle (1:1), every second cardiac cycle (1:2), or every third cardiac cycle (1:3). It is also possible to decrease the volume the balloon inflates to by decreasing the amount of gas injected into it.
  4. “Timing”. Two methods are commonly used to time or “trigger” the IABP. It can be triggered from the arterial waveform recorded from the catheter tip, or it can be timed to the QRS complex of the cardiac monitor. The arterial waveform usually works better if the patient is having arrhythmias. The IABP should inflate just after closure of the aortic valve. This corresponds to the dicrotic notch on the arterial waveform. If it inflates too late, its ability to “augment” and effectiveness will be limited. It should deflate just before left ventricular ejection. If it remains inflated during early systole it will impair LV ejection. If it deflates too early in diastole its ability to afterload reduce will be limited. The IABP console allows for manual adjustment of the balloon inflation and deflation. A cardiac perfusionist is always on call to help with adjustment of balloon timing or any “trouble-shooting” that may be required.