Imaging Techniques for Diagnosis of Thoracic Aortic Atherosclerosis

The Rationalisation of Intra-Operative Imaging During Cardiac Surgery: A Systematic Review

INTRODUCTION

One critical complication of cardiac surgery is cerebrovascular accidents (CVAs). Ascending aorta atherosclerosis poses a significant risk of embolisation to distal vessels and to cerebral arteries. Epi-aortic ultrasonography (EUS) is thought to offer a safe, high-quality accurate visualisation of the diseased aorta to guide the surgeon on the best surgical approach to the planned procedure and potentially improve neurological outcomes post-cardiac surgery.

METHOD

The authors conducted a comprehensive search of PubMed, Scopus and Embase. Studies that reported on epi-aortic ultrasound use in cardiac surgery were included. Major exclusion criteria were: (1) abstracts, conference presentations, editorials, literature reviews; (2) case series with <5 participants; (3) epi-aortic ultrasound in trauma or other surgeries.

RESULTS

A total of 59 studies and 48,255 patients were included in this review. Out of the studies that reported patient co-morbidities prior to cardiac surgery, 31.6% had diabetes, 59.5% had hyperlipidaemia and 66.1% had a diagnosis of hypertension. Of those that reported significant ascending aorta atherosclerosis found on EUS, this ranged from 8.3% of patients to 95.2% with a mean percentage of 37.8%. Hospital mortality ranged from 7% to 13%; four studies reported zero deaths. Long-term mortality and stroke rate varied significantly with hospital duration.

CONCLUSION

Current data have shown EUS to have superiority over manual palpation and transoesophageal echocardiography in the prevention of CVAs following cardiac surgery. Yet, EUS has not been implemented as a routine standard of care. Extensive adoption of EUS in clinical practice is warranted to aid large, randomised trials before making prospective conclusions on the efficacy of this screening method.

Vessel wall MR imaging of aortic arch, cervical carotid and intracranial arteries in patients with embolic stroke of undetermined source: A narrative review

Despite advancements in multi-modal imaging techniques, a substantial portion of ischemic stroke patients today remain without a diagnosed etiology after conventional workup. Based on existing diagnostic criteria, these ischemic stroke patients are subcategorized into having cryptogenic stroke (CS) or embolic stroke of undetermined source (ESUS). There is growing evidence that in these patients, non-cardiogenic embolic sources, in particular non-stenosing atherosclerotic plaque, may have significant contributory roles in their ischemic strokes. Recent advancements in vessel wall MRI (VW-MRI) have enabled imaging of vessel walls beyond the degree of luminal stenosis, and allows further characterization of atherosclerotic plaque components. Using this imaging technique, we are able to identify potential imaging biomarkers of vulnerable atherosclerotic plaques such as intraplaque hemorrhage, lipid rich necrotic core, and thin or ruptured fibrous caps. This review focuses on the existing evidence on the advantages of utilizing VW-MRI in ischemic stroke patients to identify culprit plaques in key anatomical areas, namely the cervical carotid arteries, intracranial arteries, and the aortic arch. For each anatomical area, the literature on potential imaging biomarkers of vulnerable plaques on VW-MRI as well as the VW-MRI literature in ESUS and CS patients are reviewed. Future directions on further elucidating ESUS and CS by the use of VW-MRI as well as exciting emerging techniques are reviewed.

Stroke Rates Following Surgical Versus Percutaneous Revascularization for Ischemic Heart Disease

PURPOSE OF REVIEW

Coronary revascularization is a commonly performed major procedure in the hospitals. Stroke is one of the dreaded complications after coronary revascularization procedures. The focus of this review is to understand the stroke risk in percutaneous cutaneous intervention (PCI) and coronary artery bypass grafting (CABG) procedures.

RECENT FINDINGS

Available data show that PCI offers less procedural stroke risk compared to CABG although the survival benefits of CABG are better in certain scenarios. Innovative advancements in techniques, pre-procedural optimum medical therapy (OMT), intraoperative neuro-monitoring, and multidisciplinary post procedural care are the few strategies in early detection and reduce stroke risk. Despite several innovations and strategies, it is evident that there is not enough data available to make concrete conclusions related to stroke risk after coronary revascularization, which warrants further investigation.

Diagnostic efficacy of intravascular ultrasound combined with Gd2O3-EPL contrast agent for patients with atherosclerosis

Atherosclerosis is a cardiovascular disease that is pathologically associated with the growth of atherosclerotic plaques and vascular vulnerability. Intravascular ultrasound (IVUS) has been used to evaluate and treat cardiovascular diseases. Accumulating evidence has demonstrated that Gd2O3-doped nanoparticles contrast can be applied for the diagnosis of human diseases. In the present study, eplerenone (EPL), a mineralocorticoid receptor antagonist, was first doped with Gd2O3 nanoparticles (Gd2O3-EPL), following which its diagnostic efficacy for use in IVUS measurements (Gd2O3-EPL-IVUS) was evaluated for patients suspected with atherosclerosis. Gd2O3-EPL-IVUS presented with higher accuracy and sensitivity compared with IVUS in diagnosing 188 patients with suspected atherosclerosis. Gd2O3-EPL-IVUS exhibited stronger signals associated with plaque morphology compared with aloe IVUS for patients with atherosclerosis. In addition, Gd2O3-EPL-IVUS application resulted in clearer arterial plaque images compared with IVUS by binding mineralocorticoid receptors. Atherosclerosis was subsequently confirmed in all patients using computerized tomography-coronary angiography. Gd2O3-EPL-IVUS showed more accuracy in measuring vessel size, plaque burden and minimal lumen area compared with IVUS analysis alone. In conclusion, these outcomes suggest that Gd2O3-EPL-IVUS is a reliable tool for the evaluation of coronary lesions in patients with atherosclerosis.

Aortic Cannulation around Grade 5 Aortic Arch Atheroma Utilizing Transesophageal Echocardiography

A 61-year-old male with severe aortic valve stenosis was scheduled for a minimally invasive bioprosthetic aortic valve replacement. Intraoperative transesophageal echocardiography (TEE) showed a unicuspid aortic valve and extensive aortic atheromatous disease. A large atheroma with mobile components existed near the distal aortic arch. A 17-French aortic cannula was successfully placed using TEE guidance with the tip proximal to the mobile atheroma to avoid inadvertent disruption and subsequent embolic sequelae. The patient had no evidence of perioperative stroke or other complications postoperatively. This case demonstrates one strategy to manage severe atheromatous disease intraoperatively. We also review additional management options.

Comparison of Predictive Ability of Computed Tomography and Magnetic Resonance Imaging in Patients with Carotid Atherosclerosis Complicated with Stroke

BACKGROUND

To investigate the characterizations of CT (computed tomography) and MRI (magnetic resonance imaging) in patients with carotid atherosclerosis.

METHODS

A retrospective analysis was performed on the medical records of 264 patients with carotid atherosclerosis underwent CT and MRI in Linyi Central Hospital, Linyi, China from January 2010 to January 2016. Among them, 142 patients with ischemic stroke were in experimental group (test group), another 122 patients in control group. The lumen stenosis degree, plaque fibrous cap status, calcification information and vascular plaque hemorrhage in the carotid artery fork of patients detected by CT and MRI were collected.

RESULTS

The detection rate of the plaque calcification of patients detected by MRI was lower than that detected by CT in the experimental group (P<0.05). Patients in the experimental group had higher average vascular stenosis degree detected by CT and MRI than those in the control group (P<0.01). The average vascular stenosis degree of patients detected by MRI was higher than that detected by CT in the experimental group (P<0.05). Patients in the experimental group had higher unstable fibrous cap number detected by CT and MRI than those in the control group (P<0.01). Patients in the experimental group had significantly higher number of vascular plaque small focus hemorrhage than those in the control group (P<0.05).

CONCLUSION

Patients with carotid atherosclerotic complicated with stroke have higher plaque calcification number, vascular stenosis degree and unstable fibrous cap number. Both CT and MRI can better predict the risk of stroke.

A Large Grade 5 Mobile Aortic Arch Atheromatous Plaque: Cause of Cerebrovascular Accident

Aortic atheromas (aortic atheromatous plaques) are defined by an irregular thickening of the intima ≥2 mm, and a complex plaque is defined as a protruding atheroma ≥4 mm with or without an attached mobile component. Stroke incidence is approximately 25% in patients with mobile plaques of the aortic arch and 2% in patients with quiescent nonmobile plaques. Antiplatelet agents, oral anticoagulants, and statins have been suggested in the management of atheromas. We present an 80-year-old male, with non-ST-segment elevation myocardial infarction (NSTEMI) and chronic dysarthria, found to have an acute cerebrovascular accident (CVA) secondary to embolism from a large 12 mm aortic arch plaque, treated medically with oral antiplatelet therapy, anticoagulation, and statin therapy.

Estimation of in vivo mechanical properties of the aortic wall: A multi-resolution direct search approach

The patient-specific biomechanical analysis of the aorta requires in vivo mechanical properties of individual patients. Existing approaches for estimating in vivo material properties often demand high computational cost and mesh correspondence of the aortic wall between different cardiac phases. In this paper, we propose a novel multi-resolution direct search (MRDS) approach for estimation of the nonlinear, anisotropic constitutive parameters of the aortic wall. Based on the finite element (FE) updating scheme, the MRDS approach consists of the following three steps: (1) representing constitutive parameters with multiple resolutions using principal component analysis (PCA), (2) building links between the discretized PCA spaces at different resolutions, and (3) searching the PCA spaces in a 'coarse to fine' fashion following the links. The estimation of material parameters is achieved by minimizing a node-to-surface error function, which does not need mesh correspondence. The method was validated through a numerical experiment by using the in vivo data from a patient with ascending thoracic aortic aneurysm (ATAA), the results show that the number of FE iterations was significantly reduced compared to previous methods. The approach was also applied to the in vivo CT data from an aged healthy human patient, and using the estimated material parameters, the FE-computed geometry was well matched with the image-derived geometry. This novel MRDS approach may facilitate the personalized biomechanical analysis of aortic tissues, such as the rupture risk analysis of ATAA, which requires fast feedback to clinicians.

Iatrogenic aortic dissection after minimally invasive aortic valve replacement: a case report

BACKGROUND

As minimally invasive cardiac and vascular procedures are on the rise, the incidence of iatrogenic acute aortic dissection (IAAD) will increase. Cardiovascular professionals should be aware about the risk factors, means of prevention and best management options for IAAD in the perioperative setting.

CASE PRESENTATION

We present the successful clinical management of a complicated case of IAAD after minimally invasive aortic valve replacement.

CONCLUSION

High index of suspicion is required for prompt diagnosis of IAAD; collaboration of the whole perioperative team is imperative for management of this catastrophe.