Pictorial review: electron beam computed tomography and multislice spiral computed tomography for cardiac imaging

The pathophysiology and management of vascular calcification in chronic kidney disease patients

INTRODUCTION

Vascular calcification (VC) which is the pathological mineral deposition in the vascular system, predominantly at the intimal and medial layer of the vessel wall, is an important comorbidity in patients with chronic kidney disease (CKD) leading to significant morbidity and mortality while necessitating appropriate treatment. Our review aims to provide an in-depth analysis of the current understanding of VC.

AREAS COVERED

In this review, we first discuss the pathophysiology of VC in CKD patients, then we explain the methods to predict and assess VC. Afterwards, we provide the currently available as well as the potential therapeutic approaches of VC. We finally discuss our understanding regarding the current situation surrounding VC in our expert opinion section.

EXPERT OPINION

Predicting, assessing and treating VC is crucial and the future advances in the field of research surrounding VC will potentially occur in one or more of these three areas of clinical management. There is a current lack of evidence and consensus regarding specific therapeutic options for alleviating VC and this situation may not necessitate VC to be determined, detected, and documented before the available options are implemented. Regardless, the prediction and assessment of VC is still important and requires further improvement together with the developments in therapeutic alternatives. The future has the potential to bring better research which would guide and improve the management of this patient group. A more specialized approach consisting of targeted therapies and more tailored management plans for patients with CKD and VC is on the horizon.

Role of different imaging modalities of vascular calcification in predicting outcomes in chronic kidney disease

Vascular calcification (VC) is common among patients with chronic kidney disease (CKD). The severity of VC is associated with increased risk of cardiovascular events and mortality. Risk factors for VC include traditional cardiovascular risk factors as well as CKD-related risk factors such as increased calcium and phosphate load. VC is observed in arteries of all sizes from small arterioles to aorta, both in the intima and the media of arterial wall. Several imaging techniques have been utilized in the evaluation of the extent and the severity of VC. Plain radiographs are simple and readily available but with the limitation of decreased sensitivity and subjective and semi-quantitative quantification methods. Mammography, especially useful among women, offers a unique way to study breast arterial calcification, which is largely a medial-type calcification. Ultrasonography is suitable for calcification in superficial arteries. Analyses of wall thickness and lumen size are also possible. Computed tomography (CT) scan, the gold standard, is the most sensitive technique for evaluation of VC. CT scan of coronary artery calcification is not only useful for cardiovascular risk stratification but also offers an accurate and an objective analysis of the severity and progression.

Coronary artery calcification score is associated with mortality in Japanese hemodialysis patients

OBJECTIVE

Coronary artery calcification has been associated with higher mortality in coronary artery disease and chronic kidney disease. This study aimed to correlate coronary artery calcification score (CACS) with all-cause and cardiovascular mortalities in hemodialysis (HD) patients.

DESIGN, SETTING, SUBJECTS

A survival analysis was conducted in 200 HD patients. CACS was assessed by multidetector-row computed tomography and stratified as tertiles: group 1 (0∼105 U), group 2 (110∼1067 U), and group 3 (1094∼15481 U). The duration of follow-up was 7 years and 4 months. Kaplan-Meier method and Cox proportional hazard analysis adjusted for age and HD duration were performed to examine the impact of CACS on survival.

MAIN OUTCOME MEASURE

All-cause and cardiovascular mortalities were measured.

RESULTS

The cumulative all-cause and cardiovascular mortalities of group 1 were significantly lower than those of groups 2 and 3 (all-cause mortality: 7.6% vs. 43.3% and 52.2%, respectively, cardiovascular mortality: 3.0% vs. 22.4% and 26.9%, respectively). Cox proportional hazard analysis adjusted for age and HD duration revealed that all-cause and cardiovascular mortalities of group 1 were significantly lower than those of groups 2 and 3.

CONCLUSION

CACS is helpful to predict prognosis of HD patients independently of age and HD duration.

Coronary calcification and its association with mortality in haemodialysis patients

AIM

Coronary artery calcification (CAC) has been associated with higher mortality in chronic renal disease. The purpose of this study was to assess coronary artery calcium score (CaCs) in haemodialysis patients and to correlate calcium scores with clinical parameters and mortality.

METHODS

A cross-sectional study was conducted in 59 haemodialysis patients. CaCs was assessed by multidetector-row computed tomography and stratified as: CaCs of less than 10 Agatston units (U), no calcification; CaCs of 10-400 U, mild-to-moderate; and CaCs of more than 400 U, severe calcification. The effects of age, haemodialysis duration and biochemical and inflammatory markers on CaCs logarithm were evaluated by multiple linear regression analysis. Cox regression analysis was used to measure the impact of CaCs of more than 400 on 2-year mortality.

RESULTS

Coronary calcifications were detected in 64.5% of patients, and the median of CaCs was 31.7 U (0-589.7) with a range of 0-5790.0 U. Twenty-one (35.5%) patients had mild-to-moderate and 17 (29%) severe CaCs. Patients with severe CaCs were older and showed a higher prevalence of ischaemic heart disease and a higher body mass index (P=0.04). A trend towards higher C-reactive protein levels was found in patients with severe CaCs. Advanced age was the only variable that influenced CaCs logarithm independently. The effect of severe CaCs on 2-year mortality did not persist after adjustment for other covariates.

CONCLUSION

Coronary calcification was highly prevalent in these uraemic patients on chronic haemodialysis. A correlation was evidenced between CaCs and advanced age, but severity of the CAC score did not have an impact on 2-year mortality of this cohort.

Vascular calcification and disordered mineral metabolism in dialysis patients

Vascular calcification is an active, cell-mediated process that can involve either the intima or media of the blood vessels. The current methods used to clinically measure vascular calcification cannot distinguish between intimal (invariably atherosclerotic) and medial calcification. The high calcification scores seen in patients with end-stage renal disease likely represent a composite of high calcification burden in both sites. The severity of vascular calcification has been associated with a variety of findings including left ventricular hypertrophy and angiographic vascular stenosis as well as with all-cause and cardiovascular mortality. There is increasing evidence that disordered mineral metabolism participates in the process of vascular calcification and is one of the mechanisms whereby hyperphosphatemia, hypercalcemia, and hyperparathyroidism enhance cardiovascular and all-cause mortality of end-stage renal disease patients. There are no studies showing improved outcomes of ESRD patients with aggressive control of disordered mineral metabolism. However, the preponderance of evidence argues strongly in favor of aggressive management of these abnormalities from starting early in the course of chronic kidney disease in the hope of improving patient outcomes.

Aortocoronary Endothelial Cell-Seeded Polytetrafluoroethylene Graft: 9-Year Patency

We report a 71-year old man with coronary artery disease. Complete coronary revascularization was not possible with autologous grafts; therefore, a 4-mm expanded polytetrafluoroethylene graft was implanted that had been seeded preoperatively with autologous vascular endothelial cells. At 9-year follow-up, the patient is asymptomatic and shows a patent graft.

Coronary artery calcifications: a critical assessment of imaging techniques

The presence of coronary artery calcifications is a distinct marker of atherosclerosis and the severity of calcifications is claimed to reflect a patient's individual plaque burden. Calcium deposits can be detected non-invasively by cardiac computed tomography (CT). This enables detection of coronary artery disease in a subclinical stage, description of the extent of the disease and risk estimation of future cardiovascular events. However, calcium quantification may also be used to monitor atherosclerotic disease, for example in the context of an intensified medical treatment. For years, electron-beam CT has been considered the gold-standard for calcium scoring. However, multi-slice spiral CT has recently captured the market and seems to achieve better measuring results with regard to the accuracy and reproducibility of calcium scores because of its superior image quality. For an optimal comparability of different CT techniques the calcium load should now be reported as absolute calcium mass rather than the traditional scoring methods.