Progression and regression of atherosclerotic findings in the descending thoracic aorta detected by enhanced computed tomography

Associations Between Cardio–Ankle Vascular Index and Aortic Structure and Sclerosis Using Multidetector Computed Tomography

Aortic pulse wave velocity (PWV) has been accepted as the gold standard for arterial stiffness measurement. However, PWV depends on blood pressure (BP). To eliminate the BP dependency of PWV, the cardio–ankle vascular index (CAVI) was developed. This study aimed to define the relationship between CAVI and aortic atherosclerosis or structure on multidetector computed tomography (MDCT). Patients with (n = 49) or without (n = 49) coronary artery disease were studied. The lumen and vessel diameters and wall thickness were calculated from the cross-sectional area at the pulmonary bifurcation level by 64-slice MDCT. The CAVI was measured within 3 days before MDCT. Multivariate analysis showed that the vessel diameter of the ascending and descending aorta on MDCT depends on age, body surface area, and diastolic BP. The CAVI significantly correlated with the vessel diameter ( r = .453) and wall thickness ( r = .387) of the thoracic descending aorta ( P < .001, respectively). The CAVI was an independent predictor of the descending aortic wall thickness on multiple stepwise regression analysis. These data suggest that CAVI, a simple index, is useful for evaluating thoracic aortic atherosclerosis.

Natural history of atherosclerotic disease progression as assessed by (18)F-FDG PET/CT

The aim of this study was to assess the impact of cardiovascular risk factors and plaque inflammation on the progression of atherosclerosis as assessed by positron emission tomography/computed tomography (PET/CT) imaging with (18)F-radiolabled fluorodeoxyglucose ((18)F-FDG). This study was designed as a retrospective cohort study. Patients who received a (18)F-FDG PET/CT scan and follow-up scan 9-24 months later without systemic inflammation or steroid medication were eligible for the study. (18)F-FDG PET/CT included a full diagnostic contrast enhanced CT scan. Cardiovascular risk factors and medication were documented. Calcified plaque volume, lumen area and (18)F-FDG uptake, quantified by the target-to-background ratio (TBR), were measured in the carotid arteries, aorta and iliac arteries. Influence of cardiovascular risk factors and vessel wall inflammation on atherosclerotic disease progression was analyzed. Ninety-four patients underwent baseline and follow-up whole body (18)F-FDG PET/CT (mean follow-up time 14.5 ± 3.5 months). Annualized calcified plaque volume increased by 15.4 % (p < 0.0001), carotid and aortic lumen area decreased by 10.5 % (p < 0.0001) and 1.7 % (p = 0.045). There was no significant difference in (18)F-FDG uptake at baseline and follow-up (mean TBR 1.44 ± 0.18 vs. 1.42 ± 0.19, p = 0.18). Multiple linear regression analysis identified hypertension as an independent predictor for total, aortic and iliac calcified plaque volume progression (all p < 0.04). Carotid lumen reduction was predicted by hypercholesterolemia (p = 0.008) while aortic lumen reduction was associated with BMI and mean (18)F-FDG uptake (p ≤ 0.005). Furthermore we observed a dose response relationship between the number of cardiovascular risk factors and calcified plaque volume progression in the aorta (p = 0.03). Findings from this study provide data on the natural history of atherosclerotic disease burden in multiple vascular beds and emphasize the value of morphological and physiologic information provided by (18)F-FDG PET/CT imaging.

Extent of thoracic aortic atheroma burden and long-term mortality after cardiothoracic surgery: a computed tomography study

OBJECTIVES

We hypothesized that the extent of aortic atheroma of the entire thoracic aorta, determined by pre-operative multidetector-row computed tomographic angiography (MDCTA), is associated with long-term mortality following nonaortic cardiothoracic surgery.

BACKGROUND

In patients evaluated for cardiothoracic surgery, presence of severe aortic atheroma is associated with adverse short- and long-term post-operative outcome. However, the relationship between aortic plaque burden and mortality remains unknown.

METHODS

We reviewed clinical and imaging data from all patients who underwent electrocardiographic-gated contrast-enhanced MDCTA prior to coronary bypass or valvular heart surgery at our institution between 2002 and 2008. MDCTA studies were analyzed for thickness and circumferential extent of aortic atheroma in 5 segments of the thoracic aorta. A semiquantitative total plaque-burden score (TPBS) was calculated by assigning a score of 1 to 3 to plaque thickness and to circumferential plaque extent. When combined, this resulted in a score of 0 to 6 for each of the 5 segments and, hence, an overall score from 0 to 30. The primary end point was all-cause mortality during long-term follow-up.

RESULTS

A total of 862 patients (71% men, 67.8 years) were included and followed over a mean period of 25 ± 16 months. The mean TPBS was 8.6 (SD: ±6.0). The TPBS was a statistically significant predictor of mortality (p < 0.0001) while controlling for baseline demographics, cardiovascular risk factors, and type of surgery including reoperative status. The estimated hazard ratio for TPBS was 1.08 (95% confidence interval: 1.045 to 1.12). Other independent predictors of mortality were glomerular filtration rate (p = 0.015), type of surgery (p = 0.007), and peripheral artery disease (p = 0.03).

CONCLUSIONS

Extent of thoracic aortic atheroma burden is independently associated with increased long-term mortality in patients following cardiothoracic surgery. Although our data do not provide definitive evidence, they suggest a relationship to the systemic atherosclerotic disease process and, therefore, have important implications for secondary prevention in post-operative rehabilitation programs.

Utility of triple channel injection of contrast material with mixture of saline, with acquisition in the cephalic direction for arterial trees in the thorax using multislice computed tomography

BACKGROUND

If contrast material is injected into the cubital vein, artifacts due to high concentration of the contrast material in the vein lead to deterioration of the opacification of the thoracic aorta and the major branches. We describe a new protocol employing a combination of triple channel contrast material injection and a mixture of saline with acquisition in the cephalic direction utilizing capability of 16-slice multislice CT.

MATERIALS AND METHODS

Of 35 subjects who underwent thoracic CT, 18 were injected with 70 ml contrast each prior to scanning with acquisition in the cephalic direction during the injection of 30 ml contrast diluted 50/50 with saline, followed by the injection of 20 ml of saline (new protocol). Seventeen subjects were injected each with 100 ml contrast at 3 ml/s, with scanning in the caudal direction (ordinary protocol).

RESULTS

In the new protocol, the major branches of the aorta and the left ventricle were more opacified, but the veins were less opacified compared with the ordinary protocol, resulting in clear delineation of the thoracic aorta and the major branches without artifacts.

CONCLUSIONS

A new acquisition protocol is described in which the thoracic aorta and the major branches can be evaluated without artifact due to high CT values in the veins. Faster, more informative CT scans can be performed using diluted contrast.

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.

Long-term effect of lipid-lowering therapy on atherosclerosis of abdominal aorta in patients with hypercholesterolemia: noninvasive evaluation by a new image analysis program

Recent clinical studies have demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are effective in the prevention of cardiovascular events and regression of atherosclerotic lesions evaluated by angiography. In this study, the authors investigated how lipid-lowering therapy effects on the progression of aortic atherosclerosis by using plain and enhanced computed tomography (CT) of the lower abdominal aorta. Twenty-nine hyperlipidemic patients (mean age 61.4 +/- 7.2 yr) were enrolled in a prospective open-labeled study. All patients underwent baseline CT scanning of abdominal aorta, screening for serum lipid profile and coagulation-fibrinolysis measurement, then treatment with simvastatin was begun. After 2 years, a follow-up CT scan was done and atherosclerotic lesions were compared between baseline and on-treatment scan. In spite of significant improvement of lipid and fibrinolytic profiles by simvastatin administration, mean aortic wall thickening volume (AWV) was increased during observation period. When patients were divided into subgroups by the levels of on-treatment LDL cholesterol (LDL-C), development rate of AWV was more potently suppressed in patients whose on-treatment LDL-C were below 125 mg/dL (median LDL-C). We could not find any associations of coagulation-fibrinolysis measurements with atherosclerotic lesions. In regard to aortic calcification volume (ACV), low levels of total and HDL cholesterol and higher age were associated with aortic calcification at baseline. These results suggest that aggressive treatment with LDL-C below 125 mg/dL may suppress the progression of wall thickening and factors that promote arterial calcifications and those for wall thickening may be different.

Endovascular stent grafting in the presence of aortic neck filling defects: early clinical experience

OBJECTIVE

Although endovascular grafts have been increasingly applied to the treatment of abdominal aortic aneurysms, their use in clinical trials is limited by well-defined anatomical exclusion criteria. One such criterion is the presence of thrombus within the infrarenal neck of an aneurysm, which is thought to (1) prevent the creation of a permanent watertight seal between the graft and the vessel wall, resulting in an endoleak; (2) contribute to stent migration; and (3) increase the risk of thromboembolism. This article summarizes our experience with endovascular abdominal aortic aneurysm exclusion in 19 patients with large aortic aneurysms, significant medical comorbidities, and apparent thrombus extending into the pararenal aortic neck.

METHODS

Of 268 patients undergoing abdominal aortic aneurysm repair, 19 (7%; 17 men; mean age, 71 years) demonstrated computed tomographic and angiographic evidence of intramural filling defects at the level of the aortic neck. In no instance did these filling defects extend above the renal arteries. Endovascular grafting was performed through use of a balloon-expandable Palmaz stent and an expanded polytetrafluoroethylene graft, delivered and deployed under fluoroscopic guidance. Follow-up at 3, 6, and 12 months and annually thereafter was performed with computed tomography and duplex ultrasound scan.

RESULTS

Spiral computed tomography and aortography revealed an irregular flow-limiting defect, occupying up to 75% of the aortic circumference, in every case. The mean aneurysm size, aortic neck diameter, and neck length before the procedure were 6.1, 2.43, and 1.4 cm, respectively; the mean aortic neck diameter after the procedure was 2.61 cm. No primary endoleaks were observed after graft insertion, and no delayed endoleaks have been detected during follow-up, which ranged from 7 to 48 months (mean, 23 months). In one patient, an asymptomatic renal artery embolus was detected on immediate follow-up computed tomography, and in another patient, an asymptomatic posterior tibial embolus occurred.

CONCLUSION

No primary endoleaks, endograft migration, or significant distal embolization were observed after endografting in patients with aortic neck thrombus. The deployment of the fenestrated portion of the stent, above the thrombus and across the renal arteries, allows for effective renal perfusion, graft fixation, and exclusion of potential mural thrombus from the circulation. The presence of aortic neck thrombus may not necessarily be a contraindication to endovascular repair in select patients.

Descending aorta wall volume and coronary artery disease: a comparative study using enhanced computed tomography of the chest and coronary angiography

The study examined the association between aortic wall volume (AWV) detected by enhanced computed tomography and coronary artery atherosclerosis observed on angiography. In 180 cases, AWV was measured as the total wall volume of a 7-cm portion of the descending thoracic aorta distal from the tracheal bifurcation. Coronary artery atherosclerosis was angiographically quantified by both Gensini score, in terms of the severity of coronary artery stenosis, and Extent score, in terms of the severity of coronary artery involvement. Mean AWV values between the patients with significant coronary artery stenosis and those without significant stenosis were 9.83+/-4.04 cm3 and 8.09+/-2.39 cm3, respectively (p<0.001). AWV was a significantly independent variable for significant coronary artery disease (p=0.0097) and an Extent score > or = 60 (p=0.0092). Calcification of AWV, however, was not associated with coronary atherosclerosis. The quantification of aortic atherosclerosis was useful for diagnosing coronary artery disease.

Surgical management of ascending and aortic arch disease: refined techniques with improved results

BACKGROUND

Treatment of aneurysms of the ascending aorta, arch aorta, or both is surgically challenging and has traditionally carried a high hospital mortality rate. The use of refined operative techniques, including improved grafts, enhanced myocardial protection, retrograde cerebral perfusion with circulatory arrest, transesophageal echocardiography, and control of hematologic factors, has resulted in reduced hospital mortality rates.

METHODS

We conducted a retrospective analysis of records of 117 consecutive patients who underwent 118 procedures between March 1987 and September 1997, for graft replacement of the ascending or transverse aortic arch with or without aortic valve reconstruction or replacement. There were 67 men (57.3%) and 50 women (42.7%). The mean age was 61.4 years (range, 16 to 81 years). Aortic abnormalities were medial degeneration in 59 patients (50.0%), dissection in 28 patients (23.7%), atherosclerosis in 16 patients (13.6%), Marfan's syndrome in 8 patients (6.8%), and other in 7 patients (5.9%).

RESULTS

The ascending aorta alone was replaced in 58 patients (49.2%), ascending and arch aorta in 56 patients (47.5%), and isolated arch aorta in 4 patients (3.4%). Twenty-six patients (22.0%) required aortic valve reconstruction, 17 patients (14.4%) had separate aortic valve replacement, and 37 patients (31.4%) received a valve conduit. Overall hospital mortality rate was 3.4% (4 of 117 patients). Postoperative complications included myocardial infarction in 3 patients (2.5%), stroke in 7 patients (5.9%), pulmonary insufficiency in 22 patients (18.6%), renal insufficiency in 4 patients (3.4%), and reoperation for bleeding in 8 patients (6.8%). There were no deep sternal wound infections. Follow-up was completed for 112 (99.1%) of 113 survivors and ranged from 1 month to 10.6 years (mean, 39.5 months). Actuarial survival for patients discharged from the hospital was 87.9%+/-3.7% (standard error of the mean) at 3 years and 79.7%+/-5.8% at 6 years.

CONCLUSIONS

Graft replacement of the ascending and transverse aortic arch, although technically demanding, can be performed with low hospital mortality and morbidity rates.