intro to intra-aortic balloon counterpulsation iabp

1. Intro to intra-aortic balloon counterpulsation(IABP)

2. Basics of Intraaortic balloon pumps (IABPs) Inflate during early diastole augmenting diastolic pressure Deflate during systole reducing aortic volume and decreasing afterload Improves coronary diastolic flow, decreases myocardial systolic O2 demand

3. Polyurethane bladder mounted on flexible shaft, tip just distal to left subclavian artery Inflated w/helium (fast inflation and deflation) Triggered by ECG, �optimized� by arterial waveform

4. Indications: Cardiogenic shock due to complicated MI or reversible cause such as ischemia, myocarditis, sepsis, drug toxicity Inability to wean off bypass after cardiac surgery Refractory arrhythmia Bridge to transplantation Refractory ischemia from failed PTCA, UA, complex PTCA/stent Prophylaxis after high risk angioplasty (data-free zone)

5. Contraindications: Significant AI Abdominal aortic aneurysm Aortic dissection Severe aorto-iliac or femoral disease Uncontrolled septicemia Uncontrolled bleeding diathesis

6. Counterpulsation timing Coordinated with central aortic pressure tracing from balloon guidewire lumen using 1:2 setting Inflation should initiate at aortic valve closure � upstroke should fuse w/central aortic dicrotic notch to form �U� Deflation should initiate when distole ends just before opening of aortic valve, set early then delay until maximal decrease in systolic pressure of subsequent beat, ~10-15 mm Hg Early balloon inflation or late deflation-> increases afterload Late inflation or early deflation->submaximal augmentation

7. Management of IABP patient Check position daily w/CXR to confirm radioaque tip 2cm below top of aortic knob Anticoagulate w/heparin, PTT goal 50-70, +/- when inserted w/o a sheath ABX prophylaxis: ancef if no PCN allergy while IABP in place Platelet monitoring daily, mild to moderate thrombocytopenia common but rarely drop to <50-100K, if occurs much look for other causes such as HIT Check DP/DT pulses q8 to monitor for thromboembolic events

8. Weaning Heparin off ~4hrs prior to balloon removal (verify PTT) Always at 1:1 when off heparin Check EKG and PA line hemodynamics with each change to ensure maintenance of appropriate timing Weaning protocols: Fast: (UA, MI, s/p PTCA and EF<40%) 1:2 x 1h -> 1:4 x 1h -> 1:8 x 1h -> 1:1 x 4h -> IABP out Medium: (UA, MI, or s/p PTCA and EF<40%) 1:2 x 2h -> 1:4 x 2h ->1:8 x 2h -> 1:1 x 4h -> IABP out Slow: (cardiogenic shock) 1:2 x 4h -> 1:4 x 4h -> 1:8 x 4h -> 1:1 O/N -> in am 1:2 x 1h -> 1:4 x 1h -> 1:8 x 1h ->1:1 x 4h -> IABP out

9. Complications Limb ischemia: within hours of insertion often secondary to mechanical obstruction of vessel by balloon (reversible), late ischemia often caused by formation of local thrombus; options are to remove IABP, change IABP insertion site to contralateral femoral artery, or cross-femoral grafting Arterial dissection: aortic rupture can occur if balloon inserted into false lumen Balloon rupture: helium embolization may cause prolonged ischemia or CVA, Rx includes hyperbaric oxygen CVA: often caused by excessively proximal placement of IABP or vigorous flushing of the cetnral lumen of the balloon to correct dampened readings of the aortic pressure Sepsis: onset most prominent after 1 wk of IABP use