TR access is associated with endothelial injury and intimal
hyperplasia.
Kamiya noted intimal hyperplasia (the primary method of long-term
saphenous vein graft failure) in 68% of RAs in the prior RA
catheterization group and 39% in those from the control group
(P=0.046). Gaudino 7
examined 50 patients who underwent TR coronary angiography before CABG
and split the patients into 3 groups depending on the time interval.
Immunohistochemical analysis demonstrated extensive endothelial injury
in all examined RAs, with a trend toward a reduction in damage over
time.
Nitroglycerin-mediated dilation (NMD) and flow-mediated dilation (FMD)
are frequently used to study vasomotor function of the RA. Burstein
found that, although the NMD response showed some trend for recovery
over time, the FMD response was almost completely abolished after 9
weeks.8 Yan demonstrated that TR procedures decreased
RA NMD and FMD resulting in immediate and persistent blunting of
vasodilatory function.9
Using ultrasound imaging, studies have shown that the diameter of the RA
following TR intervention never completely returns to
baseline.10 A meta-analysis by Rashid found that,
following TR intervention, the incidence of RA occlusion within 24 hours
was 7.7%, which decreased to 5.5% at >1 week
follow-up.11. The only intervention that significantly
reduced the risk of occlusion was use of a higher dose of heparin (5,000
IU vs < 5,000).