DISCUSSION
IACD complicating coronary interventions is extremely rare and a few
cases have been reported. The rapid propagation of aortocoronary
dissection may become immediately life-threatening via several sequelae,
including hemorrhage into the pericardium resulting in cardiac
tamponade, occlusion of the contralateral coronary ostium or propagation
of the dissection into the descending aorta.7 Most
reported iatrogenic aortocoronary dissections have been related to
procedures in the RCA, especially during PCI for chronic total
occlusions. The RCA is more easily dissected in the retrograde direction
into the coronary sinus than the left main coronary artery(LMCA) because
of the presence of more smooth muscle cells and a dense matrix of
collagen type I fibers8 in the peri-ostial wall and
sino-tubular junction of the LMCA. Its mechanism involves disruption of
the coronary intima by mechanical trauma caused by aggressive
manipulation of rigid or hydrophilic guide wires, followed by vigorous
contrast injection, which, in turn, contributes to the subsequent
retrograde extension of the dissection. Over 40% of the cases usually
spread rapidly to the ascending aorta if the entry-door is not sealed
rapidly, a “wait and see” approach may be too risky. To date, the
optimal treatment of this rare entity has not been well established.
Management depends on the status of the distal coronary circulation and
the extent of aortic dissection. When possible dissection can be dealt
with deployment of stents distal to the dissection and near the ostium,
thus sealing off the entry port. Dunning et al.1categorized aortocoronary dissection according to the level of aortic
involvement, where class I denotes dissection involving only the
coronaries, class II extending up to <40 mm of the ascending
aorta, and class III reaching >40 mm of the ascending
aorta. As class I and II patients with limited involvement of the aorta
can benefit from stenting of the coronary dissection entry point without
the need for surgical intervention, it was found that urgent surgery is
the treatment of choice for class III patients with extensive dissection
or patients with hemodynamic instability and those with ischemia of one
of the aortic branches.
Aortic dissection when localized may be followed up with ECG and CT scan
if coronary blood flow has been corrected by
stenting.8 However, if the above procedure fails or
cannot be attempted without a high risk of further compromising of the
coronary circulation as in our case, surgery is the only
option.8 Surgery was also a preferred option in our
case because of the extensive aortic dissection and co-existent coronary
artery disease in RCA and LAD which was managed surgically by bypass
grafting.