Cath Lab Digest

Introduction
The association of internal carotid artery disease (ICAD) with aortic valve stenosis (AVS) constitutes a very high-risk clinical occurrence of which surgical management is still unclear, because the rate of death and stroke for combined suergry is 3%.¹ Carotid stenting before or after cardiac surgery may be a valuable option in such high-risk patients. An accurate diagnosis of any significant carotid artery stenosis is of paramount importance for a proper combined or staged surgical or endovascular repair, and for immediate results after cardiac valve surgery.² Unfortunately, in patients with AVS, the evaluation of carotid arteries by Doppler ultrasound (DUS) may be inaccurate.³ The present retrospective study is aimed to evaluate the pitfalls of DUS and the role of carotid angiography, before carotid stenting, in evaluating ICAD in patients with AVS.

Methods
We analyzed the clinical, hemodynamic and angiographic findings of 200 patients with moderate to severe AVS (aortic valve area index < 0.45 to 0.74 cm2/m2 on echocardiography) investigated in our istitution over the past 2 years (5.5% of 3600 patients undewent cardiac catheterization, mean age 68.5 ± 10.6 years). In our center, in agreement with the vascular surgery and cardiac surgery team, patients with moderate to severe AVS underwent carotid ultrasonography to assess ICAD and complete left and right catheterization with coronary artery angiography. The patients also underwent carotid artery angiography at the time of complete cardiac catheterization before confirming the indication to carotid stenting or combined surgery. On behalf of the local ethical committee, an informed consent was obtained from all patients.

DUS protocol
DUS examinations were performed with a Hewlett Packard SONOS 2500 color-coded duplex ultrasound system, according to the good-quality criteria described by the Society of Radiologists in Ultrasound,⁴ including grayscale, color Doppler, spectral DUS and using an angle of insonation of 60°.5 All studies included measurements of arterial peak systolic velocity (PSV), end-diastolic velocity, the ratio of the internal to common carotid artery velocities, and a planimetric estimation of the stenosis.

Angiographic film analysis
Angiograms were obtained by a transfemoral approach on imaging systems manufactured by Siemens Coroscope Plus (Malvern, PA). Two vessels were catheterized in each patient — common carotid arteries bilaterally. Digital subtraction angiographic images were also collected for each patient. Ipsilateral diagnostic images of the extracranial carotid arteries were obtained. An investigator, blinded to the clinical and Doppler ultrasound data, measured the stenosis in the internal carotid artery using fine calipers. Measurements were performed on the angiographic view that demonstrated the maximum severity of stenosis. The diameters of stenosis and of the distal internal carotid artery were then measured. Lesion severity was assessed following the European Carotid Surgery Trial (ECST) criteria³ for carotid arteries, using quantitative coronary angiography (QCA) analysis. A stensosis > 50% has been identified as significant stenosis.

Statistical analysis
Data are expressed by mean + SD and as percentage. A student t-test and chi-square test have been used to compare quantitative data and percentages, respectively; significance was set to p < 0.05. A StatView (SAS Institute Inc., Cary, NC) program was used for data analysis.

Results
Seventy patients with moderate to severe AVS and doubtful carotid ultrasonography underwent coincident carotid angiography (Table 1). The use of suboptimal Doppler ultrasonographic examinations are related to the anatomical or difficult evaluation of Doppler flow due to hemodynamic influences of aortic valve stenosis (Table 2). On carotid angiography, 20 patients (28.5%, male/female: 8/12, mean age 72.1 + 5.1 years) were diagnosed with critical stenosis of one (16 patients) or both (4 patients) internal carotid artery arteries (Table 3). In 5 patients, a significant ICAD was not diagnosed by DUS, whereas in 7 patients, the stenosis was underestimated by DUS (mean luminal narrowing 58 + 12.7 % versus 76.7 + 19.3 %, p < 0.03), and in the other 8 patients, DUS overstimated ICAD (77 + 12% versus 62 + 13.4%, p < 0.02). Coronary artery disease has been observed in 8 patients (mean age 78.1 + 4.3, male/female 5/3) with carotid artery stenosis (mean number of coronary vessel involved 2.0 + 0.6). No in-hospital complications were observed after combined carotid and coronary angiography. Carotid angiography was accomplished with an additional contrast volume dose of 20.7 + 10.1 ml. Out of this group, 6 patients underwent successful carotid stenting, 6 combined surgical treatments and another 8 patients were excluded from carotid endovascular or surgical repair and underwent simple cardiac surgery.