An experimental study of intra aortic balloon pumping within the intact human aorta.

OBJECTIVE

Intra-aortic balloon pumping is a therapeutic technique which carries a significant morbidity related to the interaction between the balloon catheter and the aorta. The aim of this study was to visualise directly the dynamic action of the balloon catheter within the cadaveric human aorta in an artificial circulation.

METHODS

An artificial circulation was constructed using of PVC tubing, a filter and a roller pump. A series of five intact cadaveric human aortas were then individually studied by placing each in series within the circuit. A balloon catheter was advanced via the left common iliac artery into the descending aorta under direct angioscopic vision. Balloon pumping was then commenced. The circuit was perfused with normal saline at a flow rate of 3 l/min. Pump actions of 1:1 and 1:2 were simulated. Each aorta at the end of the experiment was subjected to histological examination.

RESULTS

The balloon only appeared to make direct contact with the wall of the aorta during deflation when it was swept to one side by the circulating fluid. During maximal inflation the only points of contact were the tip of the catheter and the entry site. Side branches of the aorta were not occluded by the balloon. There was considerable atheromatous debris visualised within the lumen of the aorta. Atheromatous plaques were seen to fissure and disrupt by a pressure wave action and not by direct contact with the balloon.

CONCLUSION

The balloon catheter moves relative to the wall of the aorta during inflation and deflation. Contact between the balloon and the aorta only occurs during deflation. Side branches of the aorta are not occluded by the catheter. Plaque disruption and embolus formation appear to result from pressure wave action rather than direct contact with the balloon. This may have implications for future balloon design. Further investigation of this poorly understood interaction between the balloon and the aortic wall is required.