Training, Competency, and Credentialing Standards for Diagnostic Cervicocerebral Angiography, Carotid Stenting, and Cerebrovascular Intervention

Learning curve and proficiency metrics for transcarotid artery revascularization

BACKGROUND

When introduced to a new procedure, physicians improve their performance and reduce their procedural adverse event rates rapidly during the initial cases and then improvement slows, signaling that proficiency has been achieved. Determining when they have acquired proficiency has important implications for procedural innovation, education, credentialing, and patient safety. We analyzed the worldwide experience with transcarotid artery revascularization (TCAR), a hybrid approach to carotid revascularization, to identify the (1) procedural performance measures associated with clinical and technical adverse events; (2) target levels of performance measures that minimize adverse event rates; and (3) number of TCAR cases needed to achieve the target levels for the performance measures.

METHODS

The patient, lesion, and physician characteristics were collected for each TCAR procedure performed by each physician worldwide in an international quality assurance database. Four procedural performance measures were recorded for each procedure: flow-reversal time, fluoroscopy time, contrast volume, and total skin-to-skin time. Composite clinical adverse events (ie, transient ischemic attack, stroke, myocardial infarction, death) and composite technical adverse events (ie, aborted procedure, conversion to surgery, bleeding, dissection, cranial nerve injury, device failure), occurring within 24 hours were also recorded. Correlations between each performance measure and the clinical and technical adverse event rates were computed. The inflection points in the performance measures were identified at which no further improvements occurred in the adverse event rates. Finally, the minimum number of TCAR cases required to achieve the target performance measure levels was computed.

RESULTS

A total of 18,240 procedures performed by 1273 physicians were analyzed. Of the 18,240 patients, 34.9% were women and 62.5% were asymptomatic. The flow-reversal time correlated with clinical adverse events adjusted for age, sex, and symptomatic status (R2 = 0.91; P < .0001) and adjusted technical adverse events (R2 = 0.86; P < .0001). The skin-to-skin time correlated with adjusted technical adverse events (R2 = 0.92; P < .0001). A reduction in flow-reversal times to <13.1 minutes and the skin-to-skin time to <81 minutes did not translate into further improvements in the adverse event rates. A minimum of 26 TCAR cases was required to achieve the target flow-reversal time, and a minimum of 15 cases was required to achieve the target skin-to-skin time.

CONCLUSIONS

The flow-reversal time and skin-to-skin time are appropriate performance measures for establishing the level of expertise of physicians as they acquire skills to perform TCAR. A target time of ≤13.1 minutes for flow-reversal and 81 minutes for skin-to-skin time minimized the adverse event rates. Familiarity with the steps involved in performing TCAR was achieved after ≥15 cases, and minimizing clinical adverse events occurred after ≥26 cases.

Aortic arch types and postoperative outcomes after carotid artery stenting in asymptomatic and symptomatic patients

BACKGROUND

The aim of this study was to investigate the influence of the aortic arch type on technical and clinical success of carotid artery stenting (CAS) procedure.

METHODS

Clinical and anatomical data of consecutive patients who underwent CAS from 2010 to 2018 were prospectively collected and retrospectively analyzed. Primary outcome was technical success, define as successful stent delivery and deployment and <30% residual carotid stenosis. Secondary outcomes were death, stroke, myocardial infarction (MI) and transient ischemic attack (TIA) rates at 30 days after CAS. Subgroups analysis with asymptomatic and symptomatic patients were also performed.

RESULTS

During the study period, 523 patients were enrolled and analyzed. Among these, 176 (33.6%) had Type I, 227 (43.4%) had Type II and 120 (23.0%) had Type III or bovine aortic arch (BAA) type. Technical success rate was achieved in 96.0% of cases. At 30 days, if compared with Type I or II, patient with Type III or BAA experienced a higher death rate (0 vs. 0 vs. 1.8%, respectively; P=0.056) and combined postoperative stroke/TIA rate (3% vs. 2.8% vs. 9.9%, respectively; P=0.012). No differences for same outcomes between asymptomatic and symptomatic patients were described, although the latter group experienced more postoperative MI. A multivariate analysis revealed Type III or BAA as an independent risk factor for postoperative stroke/TIA (HR 3.23, IC95% 1.40-7.45; P=0.006).

CONCLUSIONS

In this cohort of patients, death and postoperative neurological complications rates were associated with Type III or BAA, irrespective of symptomatic patients' status. Extremely attention is required during perioperative period in patients who were candidate to CAS and with challenging aortic arch anatomy.

Segmentation-Based Blood Flow Parameter Refinement in Cerebrovascular Structures Using 4-D Arterial Spin Labeling MRA

OBJECTIVE

Cerebrovascular diseases are one of the main global causes of death and disability in the adult population. The preferred imaging modality for the diagnostic routine is digital subtraction angiography, an invasive modality. Time-resolved three-dimensional arterial spin labeling magnetic resonance angiography (4D ASL MRA) is an alternative non-invasive modality, which captures morphological and blood flow data of the cerebrovascular system, with high spatial and temporal resolution. This work proposes advanced medical image processing methods that extract the anatomical and hemodynamic information contained in 4D ASL MRA datasets.

METHODS

A previously published segmentation method, which uses blood flow data to improve its accuracy, is extended to estimate blood flow parameters by fitting a mathematical model to the measured vascular signal. The estimated values are then refined using regression techniques within the cerebrovascular segmentation. The proposed method was evaluated using fifteen 4D ASL MRA phantoms, with ground-truth morphological and hemodynamic data, fifteen 4D ASL MRA datasets acquired from healthy volunteers, and two 4D ASL MRA datasets from patients with a stenosis.

RESULTS

The proposed method reached an average Dice similarity coefficient of 0.957 and 0.938 in the phantom and real dataset segmentation evaluations, respectively. The estimated blood flow parameter values are more similar to the ground-truth values after the refinement step, when using phantoms. A qualitative analysis showed that the refined blood flow estimation is more realistic compared to the raw hemodynamic parameters.

CONCLUSION

The proposed method can provide accurate segmentations and blood flow parameter estimations in the cerebrovascular system using 4D ASL MRA datasets.

SIGNIFICANCE

The information obtained with the proposed method can help clinicians and researchers to study the cerebrovascular system non-invasively.

Assessment of an introductory cervicocerebral catheter angiography learning program: a pilot study

BACKGROUND AND PURPOSE

There is no standardized curriculum currently available at most institutions for establishing procedural competency in trainees performing cervicocerebral angiography. The purpose of this study was to evaluate a simple learning program to supplement the teaching of basic cervicocerebral angiography.

MATERIALS AND METHODS

An 11-session interactive curriculum was implemented covering anatomic, clinical, and radiographic topics for the novice cervicocerebral angiographer. The target learner was the neuroradiology fellow. Data were gathered regarding fellow comfort level on topics relating to cervicocerebral angiography by using a 5-point Likert scale. Improvement in scores on knowledge-based questions after completion of the curriculum was calculated (McNemar test). Trainee-perceived utility of the program was also recorded by using a 5-point Likert scale. Focus sessions were held at the completion of the curriculum to gather feedback regarding the strengths and weaknesses of the program from participants.

RESULTS

Ten subjects were enrolled in this pilot study for 3 years. Topics where participants reported a poor initial comfort level (4 or higher) included selection of injection rates and volumes and reformation of reverse-curve catheters. Trainees demonstrated a statistically significant change in the distribution of scores of 29.3% (49.4%-78.7% correct response rate, P < .0001). The average perceived utility was 1.5 (1 = most useful, 5 = least useful).

CONCLUSIONS

This simple learning program was a useful adjunct to the training of fellows in diagnostic cervicocerebral angiography, resulting in quantitative improvements in knowledge.

The Role of 3 Tesla MRA in the Detection of Intracranial Aneurysms

Intracranial aneurysms constitute a common pathological entity, affecting approximately 1–8% of the general population. Their early detection is essential for their prompt treatment. Digital subtraction angiography is considered the imaging method of choice. However, other noninvasive methodologies such as CTA and MRA have been employed in the investigation of patients with suspected aneurysms. MRA is a noninvasive angiographic modality requiring no radiation exposure. However, its sensitivity and diagnostic accuracy were initially inadequate. Several MRA techniques have been developed for overcoming all these drawbacks and for improving its sensitivity. 3D TOF MRA and contrast-enhanced MRA are the most commonly employed techniques. The introduction of 3 T magnetic field further increased MRA's sensitivity, allowing detection of aneurysms smaller than 3 mm. The development of newer MRA techniques may provide valuable information regarding the flow characteristics of an aneurysm. Meticulous knowledge of MRA's limitations and pitfalls is of paramount importance for avoiding any erroneous interpretation of its findings.

Lumen morphology in mild-to-moderate internal carotid artery stenosis correlates with neurological symptoms

BACKGROUND

Several prospective studies have shown that carotid endarterectomy can reduce the risk for subsequent ischemic stroke in patients with 70-99% stenosis of the internal carotid artery (ICA). However, its benefits are still controversial in less than 70% stenosis of the ICA. There is increasing evidence that carotid lumen irregularities may correlate with neurological symptoms. Recent development of computed tomography angiography (CTA) can provide adequate information on the carotid plaque morphology. In this study, therefore, we aimed to clarify whether carotid lumen morphology estimated by CTA correlates with neurological symptoms in patients with 30-69% ICA stenosis.

METHODS

This study included 67 carotid stenotic lesions with 30-69% ICA stenosis in 52 consecutive patients. These 67 lesions were examined by CTA from the viewpoints of the degree of stenosis, the prevalence of ulceration, and lumen morphology. Multivariate analysis was performed to detect significant predictors for the occurrence of ipsilateral ischemic events.

RESULTS

Multivariate analysis showed that the irregular shape of the carotid lumen was the most powerful variable to predict symptomatic lesion in 30-69% ICA stenosis.

CONCLUSIONS

These findings suggest that the morphology of carotid plaque may be associated with the occurrence of ipsilateral ischemic events in 30-69% ICA stenosis.

Training for Carotid Intervention: Preparing the Next Generation

BACKGROUND

Carotid interventions are performed to reduce the cumulative risk of stroke. The success of the procedure is dependent upon maintaining low operative risk. This article reviews the current state of training for both carotid endarterectomy (CEA) and carotid angioplasty and stenting (CAS).

METHODS

Medline searches were performed to identify articles with the combination of the following key words: carotid, endarterectomy, stent, training, assessment and simulation. Manual searches of the reference lists and related papers was conducted.

RESULTS

Training and assessment for CEA and CAS follows the traditional apprenticeship model. There is no formal training protocol or objective means of assessment for either carotid endarterectomy or stenting. Models and simulators to allow for training and assessment away from the operative theatre have been developed, and exist for both CEA and CAS.

CONCLUSION

The technology exists to allow for both training and assessment of competency to take place in a controlled and objective environment for both CEA and CAS. The use of simulation needs to be robustly evaluated and assessed to both complement and augment existing training programs to ensure that the highest standards of care are maintained for treatment of carotid territory disease. Objective competency based training and assessment is no longer unattainable. Simulators augment this process and without them operative exposure is sporadic and crisis management infrequent.

Techniques in carotid artery stenting

Endovascular carotid artery interventions are unforgiving of mistakes and poor technique. The approach should be team based where all members of the team are experienced and know their jobs perfectly. This, combined with a deep knowledge of the equipment and the anatomy will reduce complications to a minimum. Patient selection and the experience of knowing how to "get out of jail" are also vital.

Carotid Artery Stenting

BACKGROUND AND PURPOSE

The prevention of stroke and the correct treatment of carotid artery stenosis represent today a major debate in cardiovascular medicine. Beside carotid endarterectomy, carotid angioplasty and stenting is becoming more widely performed for the treatment of severe carotid obstructive disease, and is now accepted as a less invasive technique that may provide an alternative for selected patients, particularly those with significant comorbidities. An Italian multidisciplinary task force, in which converged the most representative scientific societies involved in carotid treatment, was created to provide neurologists, radiologist, cardiologists, vascular surgeons, and all those involved in prevention and treatment of carotid disease with a simple, clear and updated evidence-based consensus document.

SUMMARY OF REVIEW

This First Consensus Document of the ICCS (Italian Consensus Carotid Stenting)/SPREAD group addressed the main issues related to methodology, definition of symptomatic and asymptomatic carotid stenosis, indication and procedures for carotid artery stenting, including the use of devices for preventing procedural embolic complications. Special attention was paid to credentials and competency for physicians qualifications to perform vascular angioplasty and stent placement, including training, acceptable complication rates and certification.

CONCLUSIONS

As any guideline or consensus statement, also this document is valid as long as the evidence on which it is based remains up-to-date. In such a fast-evolving field of medicine as the management of carotid stenosis, it is mandatory to stimulate a continuous and fruitful discussion among all the professionals involved in this very evolutionary field.

Current Diagnostic Modalities for Intracranial Aneurysms

Aneurysm diagnosis has evolved considerably over the last years. Technological advances have brought CT angiography and MR angiography to the forefront of ruptured and nonruptured intracranial aneurysm diagnosis. This article highlights current diagnostic modalities for intracranial aneurysms.

Complications and Follow-up after Unprotected Carotid Artery Stenting

PURPOSE

This prospective study was undertaken to determine the success rate, complications, and outcome of carotid artery stenting (CAS) without the use of cerebral protection devices.

METHODS

During 12 months, 94 high-grade stenoses of the carotid artery in 91 consecutive patients were treated. Sixty-six (70%) of the stenoses were symptomatic and 28 (30%) were asymptomatic.

RESULTS

In all 94 carotid stenoses CAS was successfully performed. During the procedure and within the 30 days afterwards, there were 2 deaths and 3 major strokes in the 66 symptomatic patients, resulting in a combined death and stroke rate of 5 of 66 (7%). Only one of these complications, a major stroke, occurred during the procedure. In the 6-month follow-up, one additional major stroke occurred in a originally symptomatic patient resulting in a combined death and stroke rate of 6 of 66 (10%) for symptomatic patients at 6 months. No major complications occurred in asymptomatic patients during the procedure or in the 6-month follow-up period. At 6 months angiographic follow-up the restenosis rate with a degree of >50% was 3 of 49 (6%) and the rate with a degree of >or=70% was 1 of 49 (2%).

CONCLUSIONS

Cerebral embolization during CAS is not the only cause of the stroke and death rate associated with the procedure. The use of cerebral protection devices during the procedure may therefore not prevent all major complications following CAS.