Innominate artery atheroma: a lesion seen with gadolinium-enhanced MR angiography and often missed by transesophageal echocardiography

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.

Atheroma of the Innominate Artery Presenting as a Transient Ischemic Attack

Supra-aortic atherosclerotic lesions, including innominate artery atheromas, are an uncommon but established cause of transient ischemic attacks, stroke, upper extremity ischemia, and vertebrobasilar insufficiency.

We present a patient with a transient ischemic attack admitted with right hemispheric symptoms who was found to have a severe ulcerated innominate artery atheroma. The patient underwent an aortic arch angiogram with stenting of the innominate artery.

The proper diagnosis, treatment, and management of innominate artery atheromas are imperative to prevent further cardiovascular morbidity and mortality in patients. Currently, both endovascular and surgical options are available for revascularization, and there have been no randomized controlled trials comparing endovascular versus open repair to standardize one as the standard of care over the other. No randomized controlled trials are examining the benefit of dual versus single antiplatelet therapy post-stenting in supra-aortic atherosclerotic lesions. We believe that this topic warrants further research and needs evidence-based guidelines to help direct physicians about treatment and management.

The association between aortic regurgitation and undetermined embolic infarction with aortic complex plaque

Background Retrograde embolism from the descending thoracic aorta is one possible cause of undetermined ischemic stroke. Significant aortic regurgitation can increase the amount of reversed flow in the thoracic aorta and thus is associated with an increased incidence of stroke. Aims This study aimed to examine the association between significant aortic regurgitation and undetermined embolic infarction with aortic complex plaques. Methods This study included 380 patients with undetermined embolic stroke who did not have abnormal flow such as atrial septal defect, patent foramen ovale determined by agitated saline bubble test, intracardiac thrombi on transesophageal echocardiography, atrial fibrillation, or small vessel stroke, cerebral artery, and carotid stenosis on the brain magnetic resonance imaging. The patients were divided into the complex aortic plaques group (n = 63), which was defined as having plaque with >4 mm in thickness, ulceration, or high mobility, and the no complex aortic plaques group (n = 317). Results Transesophageal echocardiography with a bubble study, brain MRI, and laboratory tests were performed for all subjects. Significant aortic regurgitation was more prevalent in patients with undetermined embolic stroke and complex aortic plaques than in patients without complex aortic plaques (adjusted OR = 4.981; 95% CI = 1.323-18.876, P = 0.028). In addition, the distribution of complex aortic plaques according to the severity of aortic regurgitation in patients with undetermined embolic stroke had a tendency toward the ascending thoracic aorta and proximal aortic arch. Conclusions Significant aortic regurgitation may affect undetermined embolic stroke in patients with complex aortic plaques.

Antithrombotic therapy in aortic diseases: A narrative review

Aortic diseases are a heterogeneous group of disorders, including atherothrombotic conditions like aortic atheroma, cholesterol embolization syndrome, aortic mural thrombus, thrombus within an aneurysm, and large vessel vasculitis. In this review, we provide a summary of the current evidence regarding atherothrombotic diseases of the aorta, focusing on therapeutic avenues. In patients with previous stroke, aortic arch atheroma is recognized as a strong predictor of recurrent atheroembolism, and antiplatelet therapy alone is still associated with a high (11.1%) residual risk of recurrent stroke. In secondary prevention, the use of dual antiplatelet therapy or moderate intensity anticoagulation with warfarin may lower the risk of recurrent stroke at a cost of increased life-threatening bleeding. Thrombi adherent to the aortic wall are generally associated with underlying atherosclerosis or aneurysmal disease. Primary aortic mural thrombus is a rare condition, sometimes related with systemic prothrombotic or inflammatory diseases. Retrospective studies suggest that anticoagulation is beneficial in patients with mobile mural thrombus. The pathogenesis and consequences of thrombus in an aortic aneurysm, or in an endograft following endovascular aneurysm repair, have been studied, but the role of antiplatelet therapy in those two conditions is still unclear and should be driven by general cardiovascular risk prevention. The benefit of anticoagulation to reduce thrombus load is uncertain. Patients with large vessel vasculitis experience increased cardiovascular events secondary to inflammation-driven atherothrombotic processes. Antiplatelet therapy is recommended as part of the therapy for prevention of cardiovascular disease. Anticoagulation with warfarin has shown limited benefit in few retrospective studies.

Complications of aortic atherosclerosis: Atheroemboli and thromboemboli

Patients with severe aortic atherosclerosis are at high risk for stroke and other embolic complications. Therapy to prevent emboli from aortic plaque is not yet established. Therefore, patients with atherosclerosis or risk factors for embolic disease should be identified and treated aggressively. Aspirin, smoking cessation, and control of blood pressure and glucose are important. Retrospective data in patients with severe aortic plaque support the use of statins to prevent stroke. Iatrogenic embolization can occur as a result of aortic manipulation during invasive vascular procedures or cardiovascular surgery. The risks and benefits of these procedures must be carefully weighed, and alternate approaches should be considered for patients with severe aortic atherosclerosis. For those who require coronary artery bypass graft (CABG) surgery, off-pump CABG is an option. Prophylactic aortic arch atherectomy should not be routinely performed. Aortic filters or stenting have been introduced but have not yet been fully evaluated. For patients who require angiography and have severe descending aortic, aortic arch, or abdominal aortic plaque, it is possible that a brachial (rather than a femoral) approach may avoid embolic complications.

A novel acoustic window for trans-oesophageal echocardiography by using a saline-filled endotracheal balloon

BACKGROUND

The main structures anterior to the trachea are frequently poorly visualized by trans-oesophageal echocardiography (TEE) because of the tracheal air column. We studied a new acoustic window for TEE imaging of large vessels anterior to the trachea by using a saline-filled endotracheal balloon.

METHODS

Cardiac surgery patients were studied. After ventilation was discontinued at the beginning of cardiopulmonary bypass, a saline-filled latex balloon was inserted into the trachea through the tracheal tube. The structures anterior to the trachea were imaged with and without the endotracheal balloon. TEE images of the proximal aortic arch and innominate artery were classified into three grades according to the quality of images: 1, vessel not visible; 2, part of vessel wall visible; 3, entire vessel wall visible. Grade 3 was categorized as good visualization while grades 1 and 2 were categorized as inadequate. TEE images with and without balloon were compared using the Mann-Whitney U-test and Chi-square analysis. P<0.05 was considered statistically significant.

RESULTS

In 20 patients, 84% had good visualization of proximal aortic arch with presence of endotracheal balloon compared with 11% without (P<0.001). A total of 94% had good visualization of the proximal innominate artery with presence of endotracheal balloon compared with 0% without (P<0.001).

CONCLUSIONS

A new 'TEE trans-tracheal acoustic window' was established by usage of a saline-filled endotracheal balloon. This window partially eliminates the TEE blind zone and provides improved visualization of the proximal aortic arch and innominate artery.

Safety of gadodiamide mixed with a small quantity of iohexol in patients with impaired renal function undergoing coronary angiography

Gadolinium-based contrast agents can be used in diagnostic and interventional angiography, and are safe in recommended doses in patients with impaired renal function, but the image quality is usually unsatisfactory. The objective of the present study is to evaluate the safety of gadolinium mixed with a small quantity of iodine-based contrast agent and the image quality of this mixture in patients with renal insufficiency undergoing diagnostic coronary angiography. Forty-two patients with baseline creatinine level>1.5 mg/dl were randomized into gadolinium or iodine groups. In the gadolinium group gadodiamide was mixed with 1:3 iohexole and in the iodine group only this agent was used as contrast material. Peak creatinine levels 48-72 h after the procedure were measured. The primary end point was the development of contrast-induced nephropathy (CIN), defined as >25% increase of baseline creatinine levels, and the secondary end points were absolute and relative changes in baseline creatinine levels. Total contrast volumes used were not different between groups (57+/-11 ml in gadolinium and 55+/-10 ml in iodine; P=0.68). Mean creatinine level did not increase significantly in the gadolinium group (from 1.9+/-0.3 to 1.9+/-0.4 mg/dl; P=0.06), but did in the iodine group (from 2.0+/-0.4 to 2.3+/-0.5 mg/dl; P=0.001). No patient had CIN in the gadolinium group whereas 5 (23%) patients had this phenomenon in the iodine group (P=0.048). Contrast regimen was very well tolerated in the gadolinium group, with only transient headache in two patients. Gadodiamide mixed with a small quantity of iohexol is safe in patients with azotemia undergoing diagnostic coronary angiography. The image qualities obtained with this combination are also satisfactory in all of the cases. Further evaluation of the safety of this technique is warranted, especially in other types of diagnostic and interventional procedures in which a higher amount of contrast dye is needed.

CT and MR imaging of the thoracic aorta: current techniques and clinical applications

Disease of the thoracic aorta can present with a broad clinical spectrum of symptoms and signs. The accepted diagnostic gold standard, selective digital subtraction angiography, is now being challenged by state-of-the-art CT angiography (CTA) and MR angiography(MRA). Currently, in many centers, cross-sectional imaging modalities are being used as the first line of diagnosis to evaluate the cardiovascular system, and conventional angiography is reserved for therapeutic intervention. Understanding the principles of CTA and MRA techniques is essential to acquire diagnostic images consistently. This article reviews current CTA and MRA methods used in the evaluation of thoracic aortic disease.

From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part I

Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document focuses on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.

New balloon-thermography catheter for in vivo temperature measurements in human coronary atherosclerotic plaques: a novel approach for thermography?

Although ex vivo studies showed marked thermal heterogeneity in atheromatic plaques, in in vivo human studies trivial temperature variations are recorded due to the cooling effect of blood flow. We investigated a new balloon-thermogaphy catheter for temperature measurements during coronary flow interruption. A thermistor probe is positioned at the distal segment of the catheter. At the opposite site of the thermistor, a balloon is placed. By inflation of the balloon, coronary flow is interrupted. Ten patients with effort angina were studied. Coronary flow velocity was continuously recorded. Temperature was recorded at the proximal vessel wall and at the lesion before, during, and after complete interruption of blood flow by inflation of the balloon. DeltaTp was assigned as the difference between the background temperature and the maximal temperature during and after balloon inflation. DeltaTl was assigned as the difference between the atherosclerotic plaque and the proximal vessel wall. The procedure was not complicated. DeltaTp during and after balloon inflation was 0.01 +/- 0.01 degrees C and -0.003 +/- -0.01 degrees C (P < 0.001), respectively. DeltaTl was 0.07 +/- 0.04 degrees C at baseline, 0.17 +/- 0.06 degrees C (59.3% +/- 11.8% increase) during, and 0.07 +/- 0.05 degrees C after flow interruption (P < 0.001). DeltaTl was greater than DeltaTp during and after impairment of flow (P < 0.001). In vivo atherosclerotic plaque temperature recording seems to be feasible with this new balloon-thermography catheter. This device may introduce a new approach for the detection of thermal heterogeneity in plaques by addressing the issue of cooling effect of blood flow.

Diagnostic imaging of aortic atherosclerosis and its complications

Thoracic aortic atherosclerosis has been shown to be an important cause of severe morbidity and mortality. At the present time, the case of performance, detailed information obtainable, and availability make TEE the procedure of choice for the imaging of thoracic aortic atherosclerosis; however, further technical advances in MR and CT, particularly in MR plaque characterization and the use of plaque specific contrast agents, may allow for a less invasive and more complete evaluation of thoracic aortic atherosclerosis in the near future. Gadolinium-enhanced 3DMRA is the procedure of choice for the noninvasive detection of plaque in the proximal aortic arch vessels. Furthermore, both CT and MRI are better suited to evaluate penetrating atherosclerotic ulcers and their complications such as intramural hematoma, pseudoaneurysm formation, and aortic rupture.