An arterial cannula that is too small, in addition to limiting flow,can
causehigh pressuresgradient, cavitation, increased jet of flow
velocities, jetting against the arterial wall and can increase the
likelihood of dissection, and high shear forces which may damage the
formed elements of the blood. However, diffusion-tip cannulas are
available which provide multidirectional flow to reduce jets.[5]The
tip of the cannula may be straight, tapered, or angled, as well as made
from metal or plastic. Various tip modifications, such as flanges or
adjustable rings, are available to prevent the cannula from being
inserted too far into the aorta and impeding flow to the head
vessels.[6] The inappropriately aortic cannulation can be associated
with complications like bleeding, aortic dissection, malposition of
cannula tip, atheroma dislodgement causing systemic embolism, accidental
decannulation, aortic posterior wall puncture causing fatal bleeding and
esophagealdamage. [7,8]
Our patient developed repeated LV distensions and cardiac arrests, even
after repeated successful weaning from the CPB. Trans
-esophagealechocardiography (TEE) was used to confirm any unnoticed
congenital anomalies like PDA, ASD, coartation of the aorta, extra VSD,
and VSD patch closure. After exclusion of the other possible causes of
LV dysfunction and cardiac arrest,finally we reached to the decision
that the repeated episodes of cardiac arrests were related tothe rarer
complication i.e. the aortic blood flow obstruction by the use of large
aortic cannula. The LV dysfunction and cardiac arrests were even
refractory to the very high doses of inotropes, inodilators and standard
CPR, but at last LV dysfunctions and hemodynamic graduallyimproved only
after aortic decannulation. This complication of aortic cannulation has
been hypothesized but not reported in the existing literature till date.