Risk of Acute Brain Injury Related to Cerebral Microembolism During Cardiac Catheterization Performed by Right Upper Limb Arterial Access
Background and Purpose— The primary objective of this study was to assess the incidence of new cerebral infarcts related to cardiac catheterization in patients explored through the right transradial approach.
Methods— This prospective study involved 41 consecutive patients with severe aortic valve stenosis. To assess the incidence of cerebral infarction, all patients underwent cerebral diffusion-weighted MRI before and after cardiac catheterization through the right transradial approach.
Results— We detected only two patients (4.9%) with new, small, isolated acute cerebral diffusion abnormalities postcatheterization. All patients remained asymptomatic.
Conclusions— New cerebral lesions on diffusion-weighted MRI are infrequent in patients explored through the right transradial approach. Randomized studies are warranted to confirm for potential advantages of transradial approach versus the femoral approach in cardiac catheterization.
The overall risk of cerebral infarction after cardiac catheterization is low when estimated on the basis of clinical examination. However, advances in neuroimaging techniques, like diffusion-weighted MRI (DW-MRI), have recently revealed that silent brain infarcts may occur at an unexpectedly high rate after cardiac catheterization (up to 15% to 22%).1–3
These silent cerebral infarcts related to microembolism during endovascular procedures are thought to be caused primarily by the catheter dislodging atherosclerotic debris from the descending or arch portions of the aorta.4,5 Thus, it has been suggested that using a right brachial or right radial artery catheter insertion point might reduce the risk of stroke by avoiding the negotiation of the descending aorta and aortic arch that is inherent when using a femoral artery catheter insertion point.5
We performed cerebral DW-MRI before and after cardiac catheterization in a series of consecutive patients with aortic stenosis to prospectively evaluate the incidence of new cerebral infarction when patients are explored by means of the right transradial approach (TRA).
Patients, Cardiac Catheterization
Forty-one consecutive patients, scheduled for cardiac catheterization because of aortic valve stenosis, were prospectively enrolled after informed consent was obtained. Cardiac catheterizations were performed by three experienced operators through the right TRA using 5 French catheters. All patients received 5000 IU of unfractionated heparin intravenously. After coronary angiography, retrograde catheterization of the aortic valve was performed using a long exchange guidewire (0.035-inch, 260-cm length).
DW-MRI was done during the 24 hours before and within 24 hours after cardiac catheterization using a 1.5-Tesla system (GE Health Care).
Transcranial Doppler recordings performed with a power M-mode Doppler 100 (PMD100; Spencer Technologies) were assessed by an independent investigator.
Protein S-100B Analysis
Venous blood samples were taken just before cardiac catheterization and at 8 and 24 hours after the procedure. Protein S-100B was analyzed using a commercially available assay (Elecsys S 100; Roche).
New cerebral lesions observed and estimated (midpoint of the adjusted Wald interval) were reported. The Friedman test was used to test for differences between the serum concentrations of protein S-100B at different times. Analyses were carried out using SPSS for Windows, version 14.0 (SSPS Inc., Chicago, IL).
Baseline characteristics of our study population are listed in the Table. Among the 41 patients, no changes in neurological status were documented for any patient after cardiac catheterization. The procedures were conducted using 5 French catheters in 93% and 6 French catheters in 7% of cases. The right TRA was performed successfully in 39 patients (95%). Two patients were catheterized through the right brachial artery.
Successful transcranial Doppler recordings were obtained for 17 patients of the series (41.5%) with a mean of 98±46 microembolic signals per procedure.
In the same cohort of patients, serial protein S-100B measurements were analyzed and the results are depicted in Figure 1. A significant increase in serum S-100B protein levels was found from baseline to 8 and 24 hours after the procedure with means of 0.081±0.060 μg/L, 0.097±0.060 μg/L, and 0.095±0.077 μg/L, respectively (P=0.024); no difference in mean levels was evident between 8 and 24 hours.
All 41 patients underwent cerebral DW-MRI before and after cardiac catheterization. A total of 82 DW-MRI were evaluated blindly. Before cardiac catheterization, two patients had a hyperintense focal lesion on DW-MRI. After the procedure, 2 patients had a new (Figure 2), small, acute focal hyperintense cerebral diffusion abnormality (4.9% observed; midpoint of the adjusted Wald interval 8.7% [95% CI, 0.5% to 17%]).
Among 41 consecutive patients explored through the right TRA, we identified only 2 asymptomatic patients (4.9%) with procedure-related cerebral ischemic lesions, confirming the relative safety of this form of arterial access in cardiac catheterization. The high rate of silent cerebral infarct (22%) observed previously in similar patients explored through the femoral approach might be related to prolonged catheter manipulations within the aorta as ascertained from the longer fluoroscopy times reported for this subgroup of patients.1
The atherosclerotic process leading to protruding atheroma at risk for cerebral embolism during endovascular procedures appears to start at a later age in the ascending aorta than in the descending or arch portions of the aorta. Thus, it has been suggested that a right brachial or right radial artery catheter entry point might reduce the risk of stroke by avoiding negotiation of the descending aorta and aortic arch, areas that cannot be avoided using femoral access.4,5 Our results are in keeping with this hypothesis but need to be confirmed in a randomized comparison of radial and femoral vascular access sites.
Because all cardiac catheterizations are associated with microemboli, as detected by transcranial Doppler, it has been suggested that most of these microembolisms are benign microbubbles. Other sources of embolic material are catheters and guidewires that dislodge atheromatous material from the aorta. Visible aortic debris may be seen on withdrawal of catheters during percutaneous coronary intervention.4 It has been shown that patients with cardiac catheterization-induced stroke often have multiple acute lesions on DW-MRI distinct from the occasional symptomatic lesion and consistent with a shower of embolic material. From this perspective, the increased serum levels of protein S-100B (released into the cerebrospinal fluid and blood from brain tissue after brain damage) that we observed after cardiac catheterization, independent of DW-MRI findings, can reflect more subtle and diffuse cerebral injury and warrant further investigation.
Although there is a possibility that the overall incidence of cerebral emboli using the right TRA might be lower than using the transfemoral approach, the posterior circulation supplying functionally important brain areas such as the brainstem might be more endangered by the right upper limb approach (vertebral artery arises from the subclavian artery) as compared with the transfemoral approach. Indeed, in our series, the 2 patients who had new hyperintense lesions had them in the area of the posterior circulation for one patient and possibly for the second patient.
The ischemic lesions we detected in 2 individuals were small lesions compared with the important lesions documented by some authors.1–3 The clinical impact of such small ischemic lesions will need further investigation. Future studies could assess neuropsychological consequences and the influence of concomitant therapy and the use of protective devices such as air filters.6
In conclusion, in this prospective study, we confirmed that cerebral microemboli, as detected by transcranial Doppler, occur in virtually all patients during cardiac catheterization without correlation to the degree of brain injury. Further randomized studies are warranted to confirm the potential advantages of TRA versus the more conventional femoral approach in cardiac catheterization.
- Received January 12, 2007.
- Revision received January 25, 2007.
- Accepted February 2, 2007.
Omran H, Schmidt H, Hackenbroch M, Illien S, Berhardt P, von der Recke G, Fimmers R, Flacke S, Layer G, Pohl C, Luderitz B, Schild H, Sommer T. Silent and apparent cerebral embolism after retrograde catheterization of the aortic valve in valvular stenosis: a prospective, randomised study. Lancet. 2003; 361: 1241–1246.
Busing KA, Schulte-Sasse C, Flucher S, Suelbeck T, Haase KK, Neff W, Hirsch JG, Borggrefe M, Duber C. Cerebral infarction incidence and risk factors after diagnostic and interventional cardiac catheterization—prospective evaluation by diffusion-weighted MR imaging. Radiology. 2005; 235: 177–183.
Lund C, Nes RB, Ungelstadt TP, Due-Tonnessen P, Andersen R, Hol PK, Brucher R, Russel D. Cerebral emboli during left heart catheterization may cause acute brain injury. Eur Heart J. 2005; 26: 1269–1275.
Bendszus M, Koltzenburg M, Bartsch AJ, Goldbrunner R, Günthner-Lengsfeld T, Weilbach FX, Roosen K, Toyka KV, Solymosi L. Heparin and air filters reduce embolic events caused by intra-arterial cerebral angiography. A prospective, randomized trial. Circulation. 2004; 110: 2110–2115.