How much of the intraaortic balloon volume is displaced toward the coronary circulation?

Objective

During intraaortic balloon inflation, blood volume is displaced toward the heart (V_tip), traveling retrograde in the descending aorta, passing by the arch vessels, reaching the aortic root (V_root), and eventually perfusing the coronary circulation (V_cor). V_cor leads to coronary flow augmentation, one of the main benefits of the intraaortic balloon pump. The aim of this study was to assess V_root and V_cor in vivo and in vitro, respectively.

Methods

During intraaortic balloon inflation, V_root was obtained by integrating over time the aortic root flow signals measured in 10 patients with intraaortic balloon assistance frequencies of 1:1 and 1:2. In a mock circulation system, flow measurements were recorded simultaneously upstream of the intraaortic balloon tip and at each of the arch and coronary branches of a silicone aorta during 1:1 and 1:2 intraaortic balloon support. Integration over time of the flow signals during inflation yielded V_cor and the distribution of V_tip.

Results

In patients, V_root was 6.4% ± 4.8% of the intraaortic balloon volume during 1:1 assistance and 10.0% ± 5.0% during 1:2 assistance. In vitro and with an artificial heart simulating the native heart, V_cor was smaller, 3.7% and 3.8%, respectively. The distribution of V_tip in vitro varied, with less volume displaced toward the arch and coronary branches and more volume stored in the compliant aortic wall when the artificial heart was not operating.

Conclusion

The blood volume displaced toward the coronary circulation as the result of intraaortic balloon inflation is a small percentage of the nominal intraaortic balloon volume. Although small, this percentage is still a significant fraction of baseline coronary flow.

CTSNet classification: 27

Abbreviations and Acronyms: CBF, coronary blood flow, CPB, cardiopulmonary bypass, IAB, intraaortic balloon, IABP, intraaortic balloon pump, LV, left ventricular