Central: Direct Aortic Cannulation
Over the last decade several centers have shown feasibility and safety
of direct aortic cannulation even in an acutely dissected aorta13, 28, 29. This technique allows a more rapid
initiation of cardiopulmonary bypass and offers the benefits of proximal
antegrade perfusion of the true lumen. Many surgeons use this approach
preferentially in the setting of hemodynamic instability and when
preoperative imaging shows a severe dissection/disruption of the
innominate artery. In most patients an anteriorly positioned true lumen
is observed which allow easy accessibility of the true lumen via a
needle and wire under echocardiographic guidance 27.
Other surgeons use this technique routinely even when the innominate
artery is not dissected and the true lumen is more posteriorly
positioned, reporting excellent results 13. Frederick
and colleagues have described 3 types of anatomy relevant to direct
aortic cannulation of the true lumen (Figure 1) ; Level 1 comprises
those patients, in whom a portion of the true lumen is identifiable and
accessible anteriorly in the ascending aorta; Level 2 are those patients
in whom the true lumen is posterior and the false lumen is anterior
while Level 3 are those patients in whom a complete or nearly complete
circumferential dissection of the aorta occurs, resulting in a
free-floating ascending aorta true lumen, which expands during
ventricular systole and contracts during diastole. While Level 1
provides for easy access (Figure 2), Level 2 and 3 would require the
needle to traverse through the false lumen, and puncture the
intimal-medial flap into the true lumen (Figure 3).
Some surgeons hesitate to cannulate the ascending aorta directly due to
concerns about possible rupture during cannulation. This is mostly not
observed 29. The cannulation site is eventually
excised at the time of circulatory arrest during open arch repair. At
the conclusion of the open arch repair/replacement, the arch Dacron
graft is directly cannulated to resume antegrade cardiopulmonary bypass.