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Intra-Aortic Balloon PUMP
  1. The Intra-Aortic Counter pulsation Balloon Pump (IABP) is a device used to support the failing left ventricle. It is inserted (usually percutaneously) via the femoral or axillary artery and serves to augment coronary perfusion and reduce left ventricular afterload.
  2. The IABP is most commonly inserted in the setting of high-risk coronary artery disease (CAD) with or without refractory chest pain as a bridge to definitive management (high-risk percutaneous coronary intervention [PCI] or Coronary artery bypass graft [CABG]). It may also be inserted to support a ventricle with severe mitral regurgitation or an infarct-related ventricular septal defect.
  3. The IABP is not indicated for the management of right ventricular failure as unloading of the left ventricle may worsen interventricular septal displacement and further worsening of ventricular function.
  4. Background
    1. No survival benefit to IABPs has been identified in a randomized clinical trial; however, the ease of insertion and familiarity with the device allow for its continued widespread use.
    2. The IABP consists of a flexible catheter that contains a flexible balloon that is inflated with helium in specific timing with the cardiac cycle.
    3. IABPs come in a variety of sizes (30-50 mL) with appropriate sizing chosen based on patient’s height.
    4. Placement is most appropriately guided by fluoroscopy but may be done using echocardiographic guidance or anatomic landmarks in an emergency setting.
  5. Function
    1. The IABP inflates in diastole and deflates in systole. This allows for an increase in diastolic blood pressure and a decrease in cardiac afterload during systole. In clinical practice, however, this leads to a variable effect on coronary blood flow and cardiac output.
    2. The IABP is programmed to trigger off of EKG morphology, arterial pressure, fiberoptic sensing, or manual mode. The rate of trigger is a ratio of heart rate; most commonly 1:1 or 1:2. Rates less than 1:1 require anticoagulation, and any ratio less than 1:3 provides no significant support and is only used as part of the weaning.
    3. Precise timing is necessary to ensure proper IABP function. An improperly timed IABP can have detrimental effects. Timing is checked periodically by placing the balloon pump in a 1:2 ratio in order to compare the augmented to nonaugmented pressure waveform. Figure 19.1 shows the IABP waveform.
  6. Indications
    1. IABPs are commonly inserted for the following conditions:
      1. Acute left ventricular failure
      2. Refractory angina
      3. Coronary perfusion support for high-risk CAD (usually left main disease)
      4. Chronic left ventricular failure as a bridge to heart transplant or LVAD
      5. Inability to wean from cardiopulmonary bypass
  7. Contraindications
    1. IABPs have few absolute contraindications, but in many conditions may not have significant benefit.
    2. Absolute contraindications
      1. Aortic dissection
      2. Aortic aneurysm
      3. Degree of aortic insufficiency greater than mild (IABP will increase the degree of AI.)
    3. Relative contraindications
      1. Significant atherosclerosis or peripheral vascular disease (increase the complication rate)
      2. Left ventricular outflow tract obstruction (IABP will likely worsen this phenomenon.)
      3. Tachydysrhythmias (inability for appropriate timing of IABP)
      4. Young age (Compliant blood vessels reduce the efficacy of IABP.)
  8. Complications
    1. Vascular compromise to limb
      1. Risks include preexisting vascular disease, small arteries, female gender, older age.
    2. Visceral ischemia
      1. Likely due to occlusion from IABP. Daily chest x-rays are indicated to ensure a stable IABP position.
    3. Thrombocytopenia
    4. Stroke
  9. Weaning
    1. Once support is no longer deemed necessary, the IABP is weaned by reducing the ratio from 1:1 to 1:2 to 1:4. With each ratio reduction after a period of time (usually 1-2 hours), the patient is assessed with EKGs, markers of perfusion, symptoms, and if applicable pulmonary artery catheter numbers to determine the wean is being tolerated. More patients who are critically ill may require a more prolonged wean; however, it is important that the patient remains therapeutically anticoagulated to reduce the risk of thrombus with a balloon triggering at a low ratio.
    2. The IABP is usually removed at the bedside with manual pressure. The standard procedure is as follows:
      1. The IABP is paused and the helium line disconnected.
      2. The helium port is aspirated to ensure balloon deflation.
      3. The IABP is removed with the sheath together (the balloon cannot be removed from the sheath), and the arteriotomy is allowed to bleed for 2 to 3 beats to ensure no clot.
      4. Manual pressure held for 5 minutes X French size of sheath. Additional pressure may be needed to ensure hemostasis.