Early postoperative assessment of coronary artery bypass graft patency and anatomy: value of contrast-enhanced 16-MDCT with retrospectively ECG-gated reconstructions.

OBJECTIVE: The objective of our study was to assess early postoperative patency and anatomy of off-pump coronary artery bypass grafts (CABGs) using retrospectively ECG-gated MDCT. CONCLUSION: Retrospectively ECG-gated MDCT is a promising noninvasive technique with which to assess early postoperative patency and anatomy of CABGs.

Wall mechanics of the stented extracranial carotid artery.

BACKGROUND AND PURPOSE: Abrupt compliance changes and concomitant nonlaminar flow patterns may contribute to endothelial dysfunction and subsequent neointimal thickening. The aim of this study was to test the feasibility of wall mechanics measurement using B-mode ultrasound image analysis by dedicated software in the stented human carotid artery. METHODS: Carotid Wallstents (Schneider) were placed in the extracranial carotid arteries of 15 patients. B-mode ultrasound examination was performed with a 7.5-MHz probe on the carotid artery upstream; at the proximal, mid, and distal stent levels; downstream from the stent; and on the contralateral internal and common carotid arteries. Carotid diameter (d) and systolic diameter changes (Deltad) were measured with a dedicated image processing system (IO version 3.1, IODP), while pulse blood pressure (DeltaP) was measured. Diameter compliance (Cd) and distensibility coefficient (DC) were calculated as Cd=2Deltad/DeltaP and DC=2Deltad/DeltaP/d and compared between measurement sites. RESULTS: The evaluation could be completed in 8 of 15 patients. Compliance was significantly lower at the proximal, mid, and distal stent levels (27.77+/-1.11, 27.38+/-1.08, 27.38+/-1.09x10(-3) mm x kPa(-1)) than upstream (103.3+/-36.7x10(-3) mm x kPa(-1)), downstream (91.5+/-41.3x10(-3) mm x kPa(-1)), or on the contralateral internal (87.6+/-28x10(-3) mm x kPa(-1)) and common (149.3+/-47.6x10(-3) mm x kPa(-1)) carotid arteries. CONCLUSIONS: Stenting of the extracranial carotid artery induces a compliance mismatch between the native and the stented artery.

Wall mechanics of the stented rabbit aorta: long-term study and correlation with histological findings.

PURPOSE: To evaluate long-term changes in arterial wall mechanics induced by stenting of the rabbit aorta. METHODS: Eighteen New Zealand white rabbits had initial stent deployment (3x8 mm Multilink) at 110% of the pre-stenting abdominal aortic diameter. Group A (n=10) had no postdeployment stent expansion and group B (n=8) had 30% overdilation of the stent. A noninvasive B-mode ultrasound examination coupled with image processing allowed measurement of diameters at systole and diastole and the calculation of diameter compliance. Measurements were performed before stenting and compared to those recorded immediately after stenting and at 3 months at 3 locations: upstream from the stent, at the stent level, and downstream from the stent. Measurements were also compared among measurement sites. The pathological study included measurement of intimal thickening and calculation of an injury score. RESULTS: At the stent level, diameter compliance was significantly lower after initial stenting and at 3 months than before stenting (group A: p<0.005; group B: p<0.001) and than downstream or upstream from the stent (group A: p<0.0001, group B: p<0.005). No significant difference in diameter compliance was found between groups A and B. In group B, intimal thickening and the injury score were greater than in group A (p<0.05 and p<0.0001, respectively). CONCLUSIONS: Endovascular stenting of the rabbit aorta impairs wall mechanics. Performing 30% overdilation of the stent does not worsen this impairment but induces greater in-stent intimal hyperplasia.

Arterial stenting and overdilation: does it change wall mechanics in small-caliber arteries?

PURPOSE: To evaluate changes in arterial wall mechanics induced by stent overdilation in the rabbit aorta. METHODS: Twenty New Zealand white rabbits had initial stent deployment (3-mm x 8-mm Multilink) at 10% overdilation. Group A (n=11) had no subsequent balloon expansion of the stent and Group B (n=9) had 30% overdilation of the stent. A noninvasive B-mode ultrasound examination coupled with image processing allowed the measurement of systolic and diastolic diameter and the calculation of diameter compliance (Cd) and distensibility coefficient (DC) as indexes of arterial wall biomechanics. Measurements were performed before stenting in the infrarenal aorta, after initial stenting, and after stent overdilation at 3 locations: upstream, at the stent level, and downstream from the stent. RESULTS: Cd was significantly lower in the stented aorta after initial stenting (p<0.0001) and after stent overdilation (p<0.0001) than before stenting. At the stent level, Cd and DC were significantly lower than downstream (p<0.0001) or upstream (p<0.0001) from the stent after initial stenting, as well as after stent overdilation. Downstream from the stent, Cd and DC were significantly lower after stent overdilation than before stenting (p<0.05). CONCLUSIONS: Endovascular stenting of the rabbit aorta produces a significant decrease in arterial wall compliance and distensibility. Stent overdilation is responsible for a slight additional decrease of compliance downstream from the stent.