Disrupted mobile aortic plaques are a major risk factor for systemic embolism in the elderly

Acute Upper Limb Ischemia: Prompt Surgery and Long-Term Anticoagulation Prevent Limb Loss and Debilitation

Background

Acute upper limb ischemia is an uncommon clinical manifestation of thromboembolism seen predominantly in patients with atrial fibrillation. Treatment can be by conservative or surgical means but the consensus is that after conservative treatment, symptoms still persist. In this series, an attempt was made at limb preservation and return to functional capacity by early surgery in all patients diagnosed with acute limb ischemia.

Methods

Patients referred with upper limb ischemia (22) were stratified into non-acute (6) treated with anticoagulation alone and those with acute ischemia. Sixteen (16) patients, age range 30–92 years (median 62.4 years) comprising mainly females (13), had clinical evidence of severe ischemia and underwent immediate brachial embolectomy with postoperative anticoagulation.

Results

Sixteen patients underwent 20 embolectomies with immediate reperfusion of limbs and relief of symptoms. Two patients had two re-operations each due to recurrent symptoms but both recovered with good outcome, one going on to have an axillary-radial bypass. There was no limb disability nor limb loss, but one postoperative mortality. All other patients were seen at their 1-year review and at 5 years, eleven out of 15 patients were still alive with most resuming an active lifestyle and some returning to work.

Conclusion

Good outcomes were obtained in this series in both the short and long term. Despite one mortality, there was no limb loss nor disability in a mainly elderly population. Prompt surgery and meticulous long-term anticoagulation reduced complications and improved limb salvage rates ensuring that patients had a good quality of life after surgery.

Statins reduce extensive aortic atheromas in patients with abdominal aortic aneurysms

OBJECTIVE

Statins have been used widely to reduce dyslipidemia and recently have been reported to have pleiotropic effects such as plaque reduction and stabilization. This study retrospectively evaluated the regression of extensive thoracic atheromas ("shaggy aorta") in abdominal aortic aneurysm (AAA) patients who underwent contrast-enhanced computed tomography (CECT) before and after statin administration.

MATERIALS AND METHODS

CECT was used to examine thoracic aortas of 29 patients (statin group; n = 22, non-statin group; n = 7) with extensive atheromas from the ostium of the left subclavian artery to that of the more proximal renal artery. Extensive thoracic atheroma was defined by: (1) thickness >5 mm, (2) involved circumference of thoracic aorta >50%, and (3) length >30 mm. The areas of atheroma (cm(2)) were measured before and after administration of statins, and the atheroma reduction ratio (ARR) was evaluated.

RESULTS

The area of atheroma decreased after administration of statins, and the ARR was significant (P <0.01). The ARR increased with all cases in non-statin group. No complications associated with extensive atheroma were observed during the follow-up period.

CONCLUSION

This pilot study indicates statins can reduce extensive thoracic atheromas and lower lipid concentrations.

Upper limb arterial thromboembolism: a systematic review on incidence, risk factors, and prognosis, including a meta-analysis of risk-modifying drugs

OBJECTIVES

The aim of this review is to focus on risk factors, risk-modifying drugs and prognosis for upper limb arterial thromboembolism, and the relationship between upper limb arterial thromboembolism and atrial fibrillation (AF).

METHODS

We searched MEDLINE for studies on the epidemiology of upper limb thromboembolism from 1965 to June 2012. We also searched for contemporary, phase III randomized trial data on systemic (non-stroke) thromboembolism comparing warfarin with new oral anticoagulants (OACs) in patients with atrial fibrillation published after the year 1999.

RESULTS

The incidence of upper limb thromboembolectomy was 3.3 per 100 000 person-years among men and 5.2 per 100 000 person-years among women; the risk of limb amputation, stroke and death after thromboembolectomy was increased. There was an increased risk of thromboembolectomy of the upper limb in patients with AF diagnosed with hypertension (hazard ratio [HR] 2.2-2.9), myocardial infarction (HR 2.9-3.9), heart failure (HR 1.6-1.9), and stroke (HR 2.2-3.8). For those diagnosed with diabetes mellitus, the risk was non-significantly increased by 1.2-1.4. Females had a 1.8-fold (95% confidence interval [CI] 1.5-2.3) fold increased risk of thromboembolectomy as compared with men. The risk reduction for systemic embolism with new OACs as compared with warfarin in patients with AF is similar to that seen with warfarin (odds ratio 0.79, 95% CI 0.38-1.64).

CONCLUSIONS

Age, female sex, AF, hypertension, diabetes, myocardial infarction, heart failure and stroke are most common risk factors for thromboembolectomy of the upper limb. The availability of new OACs holds promise for reducing the risk of systemic thromboembolism, but specific data are still limited.

Complex atheromatosis of the aortic arch in cerebral infarction

In many stroke patients it is not possible to establish the etiology of stroke. However, in the last two decades, the use of transesophageal echocardiography in patients with stroke of uncertain etiology reveals atherosclerotic plaques in the aortic arch, which often protrude into the lumen and have mobile components in a high percentage of cases. Several autopsy series and retrospective studies of cases and controls have shown an association between aortic arch atheroma and arterial embolism, which was later confirmed by prospectively designed studies. The association with ischemic stroke was particularly strong when atheromas were located proximal to the ostium of the left subclavian artery, when the plaque was ≥ 4 mm thick and particularly when mobile components are present. In these cases, aspirin might not prevent adequately new arterial ischemic events especially stroke. Here we review the evidence of aortic arch atheroma as an independent risk factor for stroke and arterial embolism, including clinical and pathological data on atherosclerosis of the thoracic aorta as an embolic source. In addition, the impact of complex plaques (≥ 4 mm thick, or with mobile components) on increasing the risk of stroke is also reviewed. In non-randomized retrospective studies anticoagulation was superior to antiplatelet therapy in patients with stroke and aortic arch plaques with mobile components. In a retrospective case-control study, statins significantly reduced the relative risk of new vascular events. However, given the limited data available and its retrospective nature, randomized prospective studies are needed to establish the optimal secondary prevention therapeutic regimens in these high risk patients.

Aortic arch atheroma

Severe atheroma of the aortic arch has now been established as an important risk factor and mechanism for stroke and peripheral embolism. The odds ratio for stroke or peripheral embolism in patients with severe arch atheroma is greater than four, and for mobile atheroma it is greater than 12. The prevalence of severe arch atheroma among patients presenting with acute ischaemic stroke, at over 20%, is in the same order as that of atrial fibrillation and carotid atherosclerosis. In patients with ischaemic stroke for which no cause has been identified, it is reasonable to determine as to whether they have severe arch atheroma by performing a transoesophageal echocardiogram. Recurrent stroke is common in patients with aortic arch atheroma that are thicker than 4 mm or with mobile components, particularly in the elderly, cigarette smokers, and those with hypertension or diabetes. Patients found to have severe atheroma are at high risk of recurrent events (14.2% per year) and may, therefore, need an aggressive secondary prevention strategy. Currently, there is uncertainty as to what this should be, but either combination antiplatelet therapy (aspirin plus clopidogrel) or anticoagulation with warfarin (target INR 2.0-3.0) are commonly used. Which of these is most effective will be evident after the completion of the aortic arch related cerebral hazard trial.

Calcification of the thoracic aorta as detected by spiral computed tomography among stable angina pectoris patients: association with cardiovascular events and death

BACKGROUND

Calcification of the thoracic aorta is associated with atherosclerotic risk factors, yet its pathogenesis and clinical implications are not yet elucidated. The goal of the present study was to assess whether thoracic aorta calcification is associated with an increased risk of cardiovascular events and death in patients with stable angina pectoris.

METHODS AND RESULTS

A prospective cohort of 361 stable angina pectoris patients (307 men, 54 women; age range, 37 to 83 years) underwent chest spiral computed tomography and were evaluated for aortic calcification. We recorded the incidence of cardiovascular events and death during a 4.5- to 6-year follow-up. Aortic calcification was documented in 253 patients (70% of patients; 213 men, 40 women). Patients with aortic calcification were older (mean age, 65+/-7 versus 55+/-9 years; P<0.001), and fewer were classified as smokers (13% versus 26%; P=0.014) compared with patients without aortic calcification. Significant correlation was found between patients with and those without aortic calcification for the presence of aortic valve calcification (28% versus 11%; P<0.001), mitral annulus calcification (29% versus 4%; P<0.001), and coronary calcification as expressed by coronary calcium score. (P<0.001). During 4.5 to 6 years of follow-up, 19 patients died, all of whom were in the aortic calcification group. Age-adjusted hazard ratios for total events and cardiovascular events by aortic calcification were 2.84 (95% CI, 1.52 to 5.30; P=0.001) and 2.70 (95% CI, 1.33 to 5.47; P=0.006), respectively. In multivariable analysis, hazard ratios for total events and cardiovascular events were 2.79 (95% CI, 1.46 to 5.20; P=0.002) and 4.65 (95% CI, 1.19 to 18.26; P=0.028), respectively.

CONCLUSIONS

Calcification of the thoracic aorta is age related and associated with coronary calcification and valvular calcification. Thoracic aortic calcification is associated with an increased risk of death and cardiovascular disease.

Perioperative echocardiographic examination for ventricular assist device implantation

Ventricular assist devices (VADs) are systems for mechanical circulatory support of the patient with severe heart failure. Perioperative transesophageal echocardiography is a major component of patient management, and important for surgical and anesthetic decision making. In this review we present the rationale and available data for a comprehensive echocardiographic assessment of patients receiving a VAD. In addition to the standard examination, device-specific pre-, intra-, and postoperative considerations are essential to the echocardiographic evaluation. These include: (a) the pre-VAD insertion examination of the heart and large vessels to exclude significant aortic regurgitation, tricuspid regurgitation, mitral stenosis, patent foramen ovale, or other cardiac abnormality that could lead to right-to-left shunt after left VAD placement, intracardiac thrombi, ventricular scars, pulmonic regurgitation, pulmonary hypertension, pulmonary embolism, and atherosclerotic disease in the ascending aorta; and to assess right ventricular function; and (b) the post-VAD insertion examination of the device and reassessment of the heart and large vessels. The examination of the device aims to confirm completeness of device and heart deairing, cannulas alignment and patency, and competency of device valves using two-dimensional, and color, continuous and pulsed wave Doppler modalities. The goal for the heart examination after implantation should be to exclude aortic regurgitation, or an uncovered right-to-left shunt; and to assess right ventricular function, left ventricular unloading, and the effect of device settings on global heart function. The variety of VAD models with different basic and operation principles requires specific echocardiographic assessment targeted to the characteristics of the implanted device.

Mobile aortic plaques are a cause of multiple brain infarcts seen on diffusion-weighted imaging

BACKGROUND AND PURPOSE

Multiple brain infarcts are often seen on diffusion-weighted images in cardioembolic stroke patients. Recently, mobile aortic plaques (MAPs) have been proposed as embolic sources. However, the clinical characteristics of patients with MAPs are unclear.

METHODS

We prospectively studied patients with acute ischemic stroke who underwent transesophageal echocardiography. The patients were classified into 3 groups based on transesophageal echocardiography findings: atheromatous aortic plaques <4 mm, atheromatous aortic plaques > or =4 mm without mobility, and MAPs. Based on their diffusion-weighted image findings, the patients were divided into 3 subgroups: (1) single lesion; (2) multiple lesions in a single vascular territory; and (3) multiple lesions in multiple vascular territories. We assessed the clinical characteristics and the diffusion-weighted image findings of stroke patients with MAPs.

RESULTS

One hundred sixty-seven patients (age, 70+/-12 years; 98 males) were enrolled; 128 (77%) had atheromatous aortic plaques <4 mm, 27 (16%) had atheromatous aortic plaques > or =4 mm, and 12 (7%) had MAPs. Older age, male gender, coronary artery disease, and cerebral arterial stenotic lesions were seen most frequently in patients with MAPs. On diffusion-weighted image findings, patients with MAPs were most frequent in the multiple lesions in multiple vascular territories group (P=0.001). On multiple logistic regression analysis, the National Institutes of Health Stroke Scale score (OR: 1.11; 95% CI: 1.01 to 1.22; P=0.039), arterial stenotic lesions (OR: 4.71; 95% CI: 1.35 to 16.41; P=0.015), and mobile aortic plaques (OR: 14.44; 95% CI: 2.87 to 72.66; P=0.001) were significantly associated with the multiple lesions in multiple vascular territories group.

CONCLUSIONS

MAPs were not uncommonly observed in patients with acute ischemic stroke. MAPs could cause multiple brain infarcts on diffusion-weighted images.

Aortic assessment for cardiac surgical procedures

Aortic atheromatous disease is associated with stroke in both the ambulatory and perioperative setting. In addition to atheromatous deposits, a reduction in the compliance of the aorta takes place as elastin fibers are replaced by collagen fibers. Both of these distinct processes, termed atherosclerosis, can easily be measured using transesophageal echocardiography during cardiac surgery. A review of the literature demonstrates many studies supporting the benefit of transesophageal echocardiography examination of the aorta for reducing stroke following cardiac surgery, through modification of surgical techniques. There have also been attempts by surgeons to remove atheromatous lesions from the aorta during cardiac surgery. Unfortunately, these procedures currently have a high perioperative mortality. Finally, medical therapy such as warfarin or statins may help reduce the incidence of stroke following heart surgery.

Spiral computed tomography evidence of close correlation between coronary and thoracic aorta calcifications

Coronary calcium (CC) is invariably associated with coronary atherosclerosis and can be diagnosed noninvasively by fast spiral computed tomography (dual slice mode) (CT). Calcium is often deposited in the aorta as well, but the pathogenesis, correlates and clinical implications of calcification of the aorta are not yet elucidated. A possible association between the presence of CC and thoracic aorta calcification, as detected by spiral CT, has not been investigated yet. The goal of the present work was to examine by spiral CT whether an association exists between the presence of CC and thoracic aorta calcification in patients with high risk for atherosclerotic development. Four hundred and five patients with at least two risk factors for atherosclerosis were included (212 men and 193 women, age ranged 52-79 years). All underwent chest CT for CC and aortic calcification scoring. Calcifications' thickness of > or =5 mm was considered advanced. CC was documented in 294 patients (170 men, 124 women; mean age 66 +/- 6 years, range 55-78 years). The non-CC group (control) included 111 patients (42 men, 69 women; mean age 64 +/- 6 years, range 52-79 years). Significant differences were found between CC group and control for the presence of ascending aorta calcification (69% versus 36%, P < 0.001), and advanced calcification of > or =5mm (17% versus 4%, P < 0.001). Significant differences were also found between groups regarding the presence of descending aorta calcification (60% versus 38%, P < 0.001), and number of consecutive slices with calcification (18.8 +/- 12.4 versus 10.7 +/- 8.7, P < 0.01). We identified age (in decades) (OR 1.9, 95% CI 1. 2-3.0, P < 0.001), gender (female) (OR 0.4, 95% CI 0.2-0.6, P < 0.001), and thoracic aorta calcification (OR 2.9, 95% CI 1.7-5.0, P < 0.001) as the independent variables significantly associated with CC. Only age [odds ratio (OR) 3.05, 95% confidence interval (CI) 1.86-5.01, P < 0.001] and CC (OR 2.53, 95% CI 1.26-5.08, P = 0.006) were identified as independent variables for the prediction of thoracic aorta calcification.

CONCLUSIONS

Our study demonstrated a strong association of CC and calcification of the thoracic aorta on spiral CT.

Atheroma of the aortic arch: an important and poorly recognised factor in the aetiology of stroke

Atrial fibrillation and severe carotid-artery stenosis are well-characterised risk factors for stroke; each is present in about a fifth of patients. The identification of such risk factors in patients is important because their presence calls for specific secondary prevention strategies. One region of the circulation that has received limited attention as a source of thrombus is the aortic arch. However, aortic arch atheroma is a common post-mortem finding, and it seems reasonable to speculate that atheroma might give rise to thrombi with distal embolism to the arterial tree, including the cerebral circulation. Here we review the evidence for aortic-arch atheroma as an important independent risk factor for stroke, and show that studies of the risk of stroke indicate a four times greater odds of stroke in patients with severe arch atheroma.

Thoracic aorta imaging with multisclice CT

Multislice CT aortography represents a major advance in the noninvasive evaluation of thoracic aortic disease. MSTCA is rapidly becoming the preferred modality for the initial investigation of acute aortic syndromes. Although scan quality is usually excellent, special attention to various technical parameters is required to optimize image quality. Familiarity with diagnostic pitfalls and the common imaging presentations of various thoracic aortic syndromes is necessary for accurate diagnosis.

Transcutaneous detection of aortic arch atheromas by suprasternal harmonic imaging

OBJECTIVES

The goal of the present study was to examine whether suprasternal harmonic imaging (SHI) (i.e., harmonic imaging from the suprasternal windows) can visualize protruding arch atheromas (PAAs) and reliably predict the presence or absence of significant lesions.

BACKGROUND

Protruding arch atheromas are a major source of cerebral and peripheral embolism and probably the most frequent cause of stroke during cardiac catheterization and open-heart surgery. Preprocedural screening by transesophageal echocardiography (TEE) would be desirable but is limited by the nature of the examination.

METHODS

Of 354 patients who underwent a TEE study in our laboratory during the study period, 106 were referred for detection of a source of embolism. Findings were classified based on the French Aortic Plaque study criteria as: 1) no or minimal atherosclerotic changes; 2) PAAs < 4 mm; 3) PAAs > or =4 mm or presence of a mobile component.

RESULTS

Adequate transcutaneous image quality could be achieved in 89 patients (84%). Protruding arch atheromas were present in 42 patients (47%) and absent in 47 (53%). Positive and negative predictive values for large PAAs on TEE were 91% and 98%, respectively. In one case, SHI detected a complex PAA inaccessible for TEE due to interposition of the left bronchus as demonstrated by dual helical computed tomography. Inter-observer agreement for SHI was 91%.

CONCLUSIONS

Suprasternal harmonic imaging reliably predicted or excluded the presence of PAAs in a sizable, consecutive group of patients referred to TEE for detection of a source of embolism. It represents an excellent screening test and provides complimentary views of regions, which may be blind spots for TEE.

Retrograde embolism and atherosclerosis development in the human thoracic aorta: are the fluid dynamics explanations valid?

The mechanisms of atherosclerosis development in the thoracic aorta is miscellaneous and still only partially understood. The marked variability of the sites of deposition of atherosclerotic plaques in the aorta could not be clarified based solely on the risk-factors theory of atherosclerosis. The sites of deposition of atherosclerotic plaques are considered to be affected by blood-flow patterns that cause areas of altered shear stress on the aortic wall. Close relations between protruding aortic plaques (PAP), stroke and peripheral emboli were established. The analysis of PAP distribution and motion to characterize atherogenesis in the human thoracic aorta and the pathogeneses of embolic events was performed. We concluded that protruding aortic plaques and markers of relative aortic flow instability (occurrences of vortices) are predominantly noticed in the human arch and in the descending aorta, whereas the ascending aorta showed lesser prevalence of atheromatosis. Reversal and rotational blood-flow in the thoracic aorta most likely exist in all patients with systemic emboli and mobile protruding aortic atheromas. Therefore, retrograde cerebral embolism from distal aortic plaques is conceivable.

Retrograde flow in the thoracic aorta in patients with systemic emboli: a transesophageal echocardiographic evaluation of mobile plaque motion

STUDY OBJECTIVES

Blood flow in the aorta is complex and incompletely characterized. Mobile aortic plaques (MAPs), moving freely with the pulsatile aortic flow, in fact represent natural tracers that reflect the flow pattern itself. Our aim was to use MAP motion on transesophageal echocardiography (TEE) in order to characterize flow patterns in the atheromatous thoracic aorta of patients with systemic emboli.

DESIGN AND PATIENTS

The study group was recruited from 250 patients referred for TEE to evaluate recent embolism. Among them, 22 patients (14 men and 8 women; mean +/- SD age, 66.3 +/- 7.2 years; 16 patients with cerebrovascular and 6 patients with peripheral emboli) with MAPs of > or = 3 mm in length formed the study group. The longest amplitudes of three spatial components of mobile lesion motions were measured: x (antegrade/retrograde [A/R]), y (up/down [U/D], and z (right/left [R/L]).

RESULTS

A total of 33 mobile lesions were detected: 3 in the ascending aorta (1 patient), 13 in the arch (10 patients), and 17 in the descending aorta (11 patients). The length of mobile plaque components ranged from 3 to 13 mm; amplitudes of A/R, U/d, R/L, and retrograde flow motions ranged from 3 to 26 mm, from 1 to 16 mm, from 1 to 17 mm, and from 1 to 13 mm, respectively. Systolic rotational motion was clockwise in six patients (27%), counterclockwise in five patients (23%), incomplete (semicircle) in six patients (27%), and alternate clockwise/counterclockwise in five patients (23%). Diastolic rotational motion was clockwise in 5 patients (23%), counterclockwise in 6 patients (27%), and incomplete (semicircle) in 11 patients (50%). There were 18 multiple MAPs in seven patients: in all these cases, simultaneous rotations of MAP in different directions (as a marker for the presence of multiple vortices) were found. In nine patients with cerebral embolism, MAPs on the distal part of aortic arch solely were found; in five of them, all alternative potential sources of stroke were excluded. Therefore, retrograde cerebral embolism from distal aortic plaques in these patients is highly probable.

CONCLUSIONS

Retrograde and rotational blood flow in the thoracic aorta probably exists in all patients with systemic emboli and mobile protruding aortic atheromas. Therefore, retrograde cerebral embolism from distal aortic plaques is theoretically possible.

Stroke prevention: cardiac and carotid-related stroke

The aim of this article is to discuss cardiac sources of stroke as well as the management of symptomatic and asymptomatic carotid stenosis. The authors detail the risks of cardioembolic stroke in the following conditions: aortic arch atheroma, atrial fibrillation, atrial myxoma, atrial septal aneurysm, dilated cardiomyopathy, infective endocarditis, left ventricular thrombus, mitral annular calcification, mitral valve prolapse, patent foramen ovale, prosthetic heart valves, valvular strands, and the optimal medical management for these conditions. The indications for carotid endarterectomy, angioplasty, and stenting are also outlined.

Imaging of thoracic aortic disease

Computed tomography, magnetic resonance imaging, and transesophageal echocardiography represent the relatively noninvasive techniques available for imaging thoracic aortic disease, especially in the evaluation of aneurysms and dissections. The article discusses the technique and application of these modalities in the evaluation of thoracic aorta. Imaging appearances of the commonly encountered pathologies of the thoracic aorta are presented and discussed, and potential pitfalls of technique and diagnosis are addressed.