The Impact of Aortic/Subclavian Outflow Cannulation for Cardiopulmonary Bypass and Cardiac Support: A Computational Fluid Dynamics Study

Abstract

Approximately 100 000 cases of oxygen deficiency in the brain occur during cardiopulmonary bypass (CPB) procedures each year. In particular, perfusion of the carotid and vertebral arteries is affected. The position of the outflow cannula influences the blood flow to the cardiovascular system and thus end organ perfusion. Traditionally, the cannula returns blood into the ascending aorta. But some surgeons prefer cannulation to the right subclavian artery. A computational fluid dynamics study was initially undertaken for both approaches. The vessel model was created from real computed tomography/magnetic resonance imaging data of young healthy patients. The simulations were run with usual CPB conditions. The flow distribution for different cannula positions in the aorta was studied, as well as the impact of the cannula tip distance to vertebral artery for the subclavian position. The study presents a fast method of analyzing the flow distribution in the cardiovascular system, and can be adapted for other applications such as ventricular assist device support. It revealed that two effects cause the loss of perfusion seen clinically: a vortex under the brachiocephalic trunk and low pressure regions near the cannula jet. The results suggest that cannulation to the subclavian artery is preferred if the cannula tip is sufficiently far away from the branch of the vertebral artery. For the aortic positions, however, the cannula should be injected from the left body side.

Should we change the cannulation site for right subclavian artery cannulation? An experimental study with a newly designed cannula

“…1 Kaufmann et al also showed, in one of their studies, that the closer the tip of cannula is to the vertebral artery, the higher are the steal syndrome rates due to the Venturi effect. 7 In this study, we also showed that perfusion with right subclavian artery cannulation resulted in lower pressure recordings in the right carotid artery compared to the recordings with innominate artery cannulation. The pressure gradient is most probably due to the Venturi effect.…”

Pulsatile extracorporeal circulation during on-pump cardiac surgery enhances aortic wall shear stress

“…Therefore, it is necessary to develop a method, which makes the preoperative determination of the impact of cardiopulmonary bypass on the systemic blood flow feasible. Means of computational fluid dynamics allow for a virtual evaluation of flow in the cardiovascular system and have been shown to be valid for the simulation of ECC (Tokuda et al, 2008;Fukuda et al, 2009;Kaufmann et al, 2009a). In the present study we performed numerical simulations in order to compare profiles and the impact of pulsatile ECC, non-pulsatile ECC and physiological blood flow.…”

“…Means of computational fluid dynamics have been shown to be worth to simulate flow profiles not only under physiological conditions (Lei et al, 1995;Wood et al, 2001;Shahcheragi et al, 2002;Lee and Chen, 2002), but also under ECC conditions. Recent studies revealed important information on flow patterns after direct canulation of the ascending aorta (Tokuda et al, 2008;Fukuda et al, 2009) as opposed to the axillary artery (Kaufmann et al, 2009a). Our group has recently published a comparative analysis of antegrade versus retrograde perfusion in idealized geometries (Assmann et al, 2009) and optimized outlet boundary definitions for the simulation of aortic blood flow profiles under ECC conditions (Benim et al, 2011a).…”

Aortic Outflow Cannula Tip Design and Orientation Impacts Cerebral Perfusion During Pediatric Cardiopulmonary Bypass Procedures

“…The aortic cannula must ideally be placed high up in the ascending aorta 10 but improper technique can occasionally result in profuse bleeding as a result of improper cannula placement. To date, CPB has been studied in regard to clinical stroke-risk, 2 but there have been few reported studies of the detailed fluid dynamics associated with aortic cannulation, 15,16,31,40 all underscoring the association of biomechanical risks with aortic cannulation. Despite advances in surgical techniques leading to decreased mortality after repair of complex congenital cardiac conditions, neurologic morbility is still significant.…”