Intra-aortic balloon pumps
The intra-aortic balloon pump (IABP) remains the most commonly utilised haemodynamic support system for patients with severe coronary artery disease, acute heart failure and cardiogenic shock.
Indications for IABP insertion:
- Patients with myocardial ischaemia refractory to medical therapy bridging to definitive revascularisation (coronary artery bypass grafting or percutaneous coronary intervention - PCI);
- Unstable patients post cardiac surgery;
- Patients with severe heart failure bridging to left ventricular assist device or transplant;
- Patients with cardiogenic shock post acute myocardial infarction (post primary PCI or fibrinolysis);
- Patients without shock who have undergone complex or multi-vessel PCI and stenting.
Summary of haemodynamic benefits of the IABP:
- Increased coronary artery filling pressures
- Increased myocardial perfusion
- Increased renal & cerebral perfusion
- Reduced afterload and cardiac workload
Complications of IABP:
- Neurovascular complications from femoral puncture – this may include localised haemotoma or more severe internal bleeding into the retro-peritoneal space;
- Balloon rupture – recognised by backflow of blood into the tubing;
- Balloon migration – if the balloon moves distally the renal arteries may be occluded leading to reduced renal perfusion and a subsequent drop in urine output. Migration up the aortic arch will reduce blood supply down the left arm and potentially diminish brachial and radial pulses on the affected side;
- Thromboembolus – the balloon is thrombogenic therefore most patients are commenced on IV Heparin to reduce the risk of thrombosis. Arguably the risk of clot formation on the surface of the balloon is minimal when the balloon is set to maximum augmentation on a 1:1 inflation ratio. At lower inflation ratios, where the balloon intermittently sits idle, the risk is increased;
- Infection from an invasive line;
- Aortic dissection – a rare complication increased in patients with a friable aorta i.e. those with connective tissue disorders including Marfan’s disease;
- Aortic regurgitation – if an IABP is inserted into a patient without a competent aortic valve severe aortic regurgitation will occur on balloon inflation. A competent aortic valve is therefore a pre-requisite for IABP therapy.
Care requirements for the patient receiving IABP support:
- Nurse at a maximum of 45 degrees to prevent line occlusion and/or damage to the femoral artery;
- Assess puncture site regularly for bleeding/haemotomas;
- Neurovascular observations of the lower limb distal to the puncture site;
- Assessment of perfusion to the left arm to ensure adequate balloon placement and to identify upward migration of the balloon promptly;
- Hourly urine outputs to ensure adequate renal perfusion and to indicate balloon migration early;
Regular review by an individual competent in the assessment of inflation/deflation timings to ensure optimum therapy. Depending on the organisation this may be a perfusionist, cardiac physiologist, appropriately trained nurse or cardiologist.