Background and aim During endovascular procedures for acute ischemic stroke, catheter access to the occluded vessel may be technically difficult or impossible. The aim of this study was to access the impact of difficult catheter access to target the carotid artery on clinical outcome.
Methods Anterior circulation stroke patients undergoing transfemoral endovascular procedures where studied. Patients were divided into four groups according to time from groin puncture to target carotid catheterization quartiles. Patients in quartile 4 (Q4) were considered difficult carotid access. We defined several outcome measures: recanalisation (final Thrombolysis in Cerebral Infarction score ≥2a), time from groin puncture to recanalisation and favorable long term outcome (modified Rankin Scale score <3 at 3 months).
Results Of 130 patients studied, carotid catheterization was impossible in seven patients (5.1%). These patients had significantly lower rates of recanalization (14.3% vs 80.5%; p<0.01) and favorable outcome (0% vs 36%; p=0.038). Among patients with an accessible carotid artery(n=123), median time from groin puncture to carotid catheterization was 20 min (IQR 10). A negative correlation between time to carotid access and recanalization was observed (r=−0.31; p<0.01). Patients in Q4 (>30 min) had lower rates of recanalization (60.7% vs 82.4%; p=0.02) and a lower favorable outcome (13.6% vs 41.3%; p=0.04). A logistic regression adjusted by age showed that baseline National Institutes of Health Stroke Scale score (OR 0.8; 95% CI: 0.72 to 0.92 p<0.01) and having difficult access (OR 1.3; 95% CI 1.3 to 20.1 p=0.018) independently predicted worse long term outcome.
Conclusions Difficult catheter access to target the carotid is common during acute endovascular treatment of stroke patients and is associated with a worse clinical outcome. If transfemoral access appears difficult, alternative access such as direct carotid puncture could be explored.
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The use of urgent endovascular procedures in acute ischemic stroke is rapidly growing. The mounting evidence of the benefits of the intra-arterial approach, including lytics1 or embolectomy devices,2–4 is likely to generalize these procedures in the following years. The target population for these procedures is generally the elderly and those with a high incidence of vascular risk factors. Transfemoral access, generally used in these cases, is often technically difficult and time consuming due to vessel tortuosity and aortic arch elongation and distortion.5 ,6 The urgent recanalization required in these procedures often results in delays and complications, such as dislodgment of the entire delivery system from the target vessel during the procedure or failure to catheterize with large caliber sheaths despite numerous attempts. Moreover, some patients with severe peripheral arterial disease may even have impossible transfemoral catheter access to the aortic arch.
We aim to study the incidence and impact of difficult transfemoral catheter access to target the carotid artery on clinical outcome in acute stroke patients undergoing endovascular procedures.
Consecutive acute stroke patients undergoing endovascular procedures were studied; all data were prospectively recorded in our database. At patient arrival in the emergency department, a complete evaluation was done by the neurologist on call, including a complete ultrasound evaluation (carotid arteries and transcranial Doppler).7 Eligible patients were treated with intravenous tissue plasminogen activator (tPA) before the intra-arterial procedure. Patients with a persistent arterial occlusion at the end of intravenous tPA infusion or with contraindications to intravenous tPA were treated with endovascular procedures. When clinical status allowed, a conscious sedation protocol avoiding intubation was preferred. Heparin was administered following femoral artery puncture as a 2000–3000 units intravenous bolus. For analysis purposes, to ensure a homogeneous study population, only patients with angiographically documented terminal internal carotid artery or middle cerebral artery occlusion were included in the study.
Typically, after femoral access was secured with an 11 cm 8 F sheath, efforts were made to catheterize the carotid artery ipsilateral to the presumed intracranial occlusion (target carotid) with a 4 or 5 F diagnostic catheter (usually VERT, H1, SIM2). At this point, an angiogram was performed to identify and locate the arterial occlusion. Then a 0.035 inch stiff guidewire was generally used to advance the guiding sheath (Merci Balloon Guide Catheter, Concentric or Flexor Tuohy-Borst Side-Arm; Cook) to the common or internal carotid artery. The time elapsed from groin puncture to this moment was defined as time to carotid access. Timing of all other procedural steps was also prospectively recorded. Those cases in which after several attempts the interventionalist could not catheterize the carotid artery were defined as impossible access. All other cases were divided in four groups according to time from groin puncture to target carotid catheterization quartiles. Patients in quartile 4 (Q4) were considered to have difficult carotid access.
Once carotid access was secured, the interventionalist tried to achieve recanalization with repeated local infusions of tPA (3–5 mg aliquots up to a maximum of 20 mg) and mechanical clot disruption with the guidewire and/or the Merci, Solitaire, or Trevo retrievers according to their preferences, availability, and patient characteristics. The predefined protocol, approved by the local ethics committee, indicates procedure termination when recanalization is achieved or at 6–8 h after symptom onset. Recanalization was assessed using the Thrombolysis in Cerebral Infarction grading score8 at the end of procedure. For the purposes of analysis, we considered successful recanalization as a Thrombolysis in Cerebral Infarction score≥2a and recorded time from groin puncture to recanalization. In those patients with impossible catheterization, transcranial Doppler determined recanalization9 at procedure termination. Neurological status was assessed by a certified neurologist on the patient's arrival, at 24 h, and at 7 days or discharge, using the National Institutes of Health Stroke Scale (NIHSS) score.10 A 24 h CT scan determined the presence of hemorrhage. Symptomatic hemorrhage was defined as a CT documented hemorrhage that was temporally related to deterioration in the patient's clinical condition in the judgment of the clinical investigator.11 CT readings were performed by neuroradiologists blinded to the clinical and angiographic data. The modified Rankin Scale12 was used to assess clinical outcome at 90 days.
Descriptive and frequency statistical analyses were obtained and comparisons were made using the SPSS V.15.0 statistical package. Statistical significance for intergroup differences was assessed by the Pearson χ2 or the Fisher exact test for categorical variables, and the Student's t test and ANOVA for continuous variables. When indicated, Mann–Whitney U and Spearman tests were used. To calculate correlations between continuous variables, Pearson's correlation test was used. To calculate the sensitivity and specificity of score points to predict difficult access, a receiver operating characteristic curve was configured. Logistic regression analysis was performed to determine factors that could be considered independent predictors of favorable outcome. A p value <0.05 was considered statistically significant.
Of the 136 studied patients, six (3.8%) had complete recanalization on the initial angiogram and were excluded from the analysis. Therefore, 130 patients were included: mean age 72±12 years, median baseline NIHSS 19 (IQR 4). Occlusion location was the middle cerebral artery in 76 patients (58.5%) and the terminal internal carotid artery in 54 (41.5%). None of the patients needed intubation.
Catheterization of the target carotid artery was impossible in seven patients (5.4%): two had Leriche syndrome and five an extremely tortuous aortic arch. These patients had significantly lower rates of recanalization (14.3% vs 80.5%; p<0.01) and a less favorable outcome (0% vs 36%; p=0.038).
Among patients with an accessible carotid artery, median time from groin puncture to carotid catheterization was 20 min (IQR 10–30): patients in quartile 4 (>30 min) were considered to have difficult catheter access. A negative correlation was found between time to carotid access and final recanalization (r=−0.31; p<0.01); patients with difficult access had a lower rate of recanalization (60.7% vs 82.4%; p=0.02) (figure 1). Moreover, patients with difficult catheter access also had a significantly longer procedure time (groin puncture to recanalization: 138±65 vs 98±60 min; p=0.02) but similar time from symptom onset to final recanalization (334±131 vs 335±88 min) (table 1).
At 3 months, the rate of favorable outcome progressively decreased according to catheterization time quartiles (figure 1). Patients with difficult catheter access (Q4) had a lower rate of favorable outcome (13.6% vs 41.3%; p=0.04). A logistic regression adjusted by age showed that baseline NIHSS (OR 0.8; 95% CI 0.72 to 0.92 p<0.01) and having difficult access (OR 1.3; 95% CI 1.3 to 20.1; p=0.018) independently predicted worse long term outcome.
Variables significantly associated with difficult access were: age >75 years (difficult access 67% vs 45%; p=0.037), hypertension (85 vs 64.3%; p=0.04), dyslipidemia (69% vs 40%; p<0.01) and left carotid catheterization (75% vs 41%; p<0.01). We defined a score according to the above factors to predict difficult catheter access before endovascular procedure (figure 2). A score>2 predicted difficult catheter access with 84% sensitivity and 74% specificity.
Our study shows the prevalence of difficult catheter access to the target carotid artery in acute stroke patients undergoing urgent endovascular recanalization procedures. Patients with difficult access had longer procedures, lower recanalization rates and poorer outcomes.
The use of intra-arterial procedures in the acute phase of stroke is rapidly growing. To date, most research studies have focused on the selection of patients before the procedure is initiated13 ,14 and on the best therapeutic alternatives: retrievers,3 ,4 ,15 local lytics,1 aspiration.16 ,17 However, there are a lack of studies focusing on a crucial step in the procedure—endovascular navigation and access with the guiding catheter to the affected artery.
Acute stroke patients are usually over 70 years of age and have a high incidence of vascular risk factors leading to a high prevalence of elongated and tortuous vessels that often make catheter navigation to the target vessel difficult and time consuming.5 ,6 In other elective endovascular procedures, several inventive strategies have been described to overcome these difficulties.18 ,19 The problem becomes very important in the acute stroke setting where time is crucial, and impossibility or delay in catheter delivery may lead to death or disability.
In 25% of our patients, vessel tortuosity determined more than a 30 min delay in guiding catheter delivery to the target carotid artery. These patients had not only longer procedures times but also lower rates of recanalization, probably because of the intricacy of device delivery and a suboptimal clot retrieval process. As a result, despite having a similar total time of ischemia and after adjusting for age, difficult catheter access to the parent vessel emerged as an independent predictor of long term disability.
Information about the odds of finding difficult access before starting the procedure may be useful to avoid an excessively time consuming traditional transfemoral access. We created a risk factor based score to calculate, with a relatively good predictive value, the chances of further finding difficult access. Association of left carotid strokes with difficult access may be explained by bovine origin of the left common carotid in some patients, creating a difficult angle to cross with the catheter when navigating from the femoral artery. Future studies may investigate the value of aortic arch MR angiography/CT angiography performed at the time of initial neuroimaging to improve its predictive power.
In these patients, alternative strategies, including the use of balloons or guidewires to increase the support of the catheter system, can be used to achieve robust transfemoral access to the target carotid artery. Moreover, different puncture sites such as the brachial20 ,21 or direct common carotid artery22 are worth investigating since they may dramatically reduce the time frames and facilitate the procedure.
Our study did not take into account dislodgment of the entire delivery system from the target vessel during the procedure once the carotid artery was reached. This setback usually constitutes important consumption of time that could not be computed in our analysis.
The main purpose of our study was to describe the profile of the time needed to catheterize the internal carotid artery in an acute stroke population. The association of difficult access and worse outcome may be multifactorial and not due simply to an increase in the time to catheterize the carotid artery. Patients with difficult access were indeed older and had more vascular risk factors. However, the lower final recanalization rates and longer procedure time after carotid catheterization could be attributed, at least in part, to difficult access and proximal vessel tortuosity.
Difficult or impossible catheter access to target the carotid artery is common during acute endovascular treatment of stroke patients. Difficult access is associated with worse clinical outcome. If catheter access through the femoral artery appears difficult, alternative access, such as direct carotid puncture, could be explored.
Contributors MRi: acquisition, analysis and interpretation of the data, article drafting, and final approval of the manuscript. AF, MR, JP, NM, SP, PM, DR-L, JA-S, CM: acquisition of the data, drafting the article and final approval of the manuscript.
Funding This work was supported by the Instituto de Salud Carlos III, grant No PS09/01660.
Competing interests MRi has a consulting agreement with Silk Road Medical.
Ethics approval The study was approved by the local ethics committee.
Provenance and peer review Not commissioned; externally peer reviewed.