In recent years, the mechanisms and clinical significance of vascular calcification have been increasingly investigated. For over a century, however, pathologists have recognized that vascular ...calcification is a form of heterotopic ossification. In this review, we aim to describe the pathology and molecular processes of vascular ossification, to characterize its clinical significance and treatment options, and to elucidate areas that require further investigation. The molecular mechanisms of vascular ossification involve the activation of regulators including bone morphogenic proteins and chondrogenic transcription factors and the loss of mineralization inhibitors like fetuin-A and pyrophosphate. Although few studies have examined the gross pathology of vascular ossification, the presence of these molecular regulators and evidence of microfractures and cartilage have been demonstrated on heart valves and atherosclerotic plaques. These changes are often triggered by common inflammatory and metabolic disorders like diabetes, hyperlipidemia, and chronic kidney disease. The increasing prevalence of these diseases warrants further research into the clinical significance of vascular ossification and future treatment options.
•The molecular mechanisms of vascular calcification are similar to that of bone remodeling.•Calcified arteries and valves have demonstrated cartilage, lamellar bone, and microfractures.•Several genetic factors (Madh6, NT5E, RANKL, RAGE ligand) have been implicated in calcification and may progress to ossification.•Theoretical treatments for vascular ossification may aid patients with calcified arteries.
Treatment for claudication that is due to aortoiliac peripheral artery disease (PAD) often relies on stent revascularization (ST). However, supervised exercise (SE) is known to provide comparable ...short-term (6-month) improvements in functional status and quality of life. Longer-term outcomes are not known.
The goal of this study was to report the longer-term (18-month) efficacy of SE compared with ST and optimal medical care (OMC).
Of 111 patients with aortoiliac PAD randomly assigned to receive OMC, OMC plus SE, or OMC plus ST, 79 completed the 18-month clinical and treadmill follow-up assessment. SE consisted of 6 months of SE and an additional year of telephone-based exercise counseling. Primary clinical outcomes included objective treadmill-based walking performance and subjective quality of life.
Peak walking time improved from baseline to 18 months for both SE (5.0 ± 5.4 min) and ST (3.2 ± 4.7 min) significantly more than for OMC (0.2 ± 2.1 min; p < 0.001 and p = 0.04, respectively). The difference between SE and ST was not significant (p = 0.16). Improvement in claudication onset time was greater for SE compared with OMC, but not for ST compared with OMC. Many disease-specific quality-of-life scales demonstrated durable improvements that were greater for ST compared with SE or OMC.
Both SE and ST had better 18-month outcomes than OMC. SE and ST provided comparable durable improvement in functional status and in quality of life up to 18 months. The durability of claudication exercise interventions merits its consideration as a primary PAD claudication treatment.
Background Coronary artery calcification (CAC) is associated with increased mortality risk in the general population. Although individuals with chronic kidney disease (CKD) are at markedly increased ...mortality risk, the incidence, prevalence, and prognosis of CAC in CKD are not well understood. Study Design Cross-sectional observational study. Setting & Participants Analysis of 1,908 participants who underwent coronary calcium scanning as part of the multiethnic CRIC (Chronic Renal Insufficiency Cohort) Study. Predictor Estimated glomerular filtration rate (eGFR) computed using the Modification of Diet in Renal Disease (MDRD) Study equation, stratified by race, sex, and diabetic status. eGFR was treated as a continuous and a categorical variable compared with the reference value of >60 mL/min/1.73 m2. Measurements CAC detected using computed tomography (CT) using either an Imatron C-300 electron beam computed tomography (CT) scanner or multidetector CT scanner. CAC was computed using Agatston score as a categorical variable. Analyses were performed using ordinal logistic regression. Results We found a strong and graded relationship between lower eGFR and increasing CAC. In unadjusted models, ORs increased from 1.68 (95% CI, 1.23-2.31) for eGFR of 50-59 mL/min/1.73 m2 to 2.82 (95% CI, 2.06-3.85) for eGFR <30 mL/min/1.73 m2 . Multivariable adjustment only partially attenuated the results (OR, 1.53; 95% CI, 1.07-2.20) for eGFR <30 mL/min/1.73 m2. Limitations Use of eGFR rather than measured GFR. Conclusions We showed a graded relationship between severity of CKD and CAC independent of traditional risk factors. These findings support recent guidelines that state that if vascular calcification is present, it should be considered as a complementary component to be included in the decision making required for individualizing CKD treatment.
Departments of 1 Radiology, 2 Neurology, 3 Medicine, 4 Biostatistics and Epidemiology, and 5 Anesthesiology and Critical Care, The Hospital of University of Pennsylvania, Philadelphia, Pennsylvania; ...and 6 Graduate Institute of Clinical Medicine, National Taiwan University, Taipei, Taiwan
Submitted 4 December 2007
; accepted in final form 28 February 2008
Arterial spin labeling (ASL) is a noninvasive magnetic resonance imaging (MRI) technique for microvascular blood flow measurement. We used a continuous ASL scheme (CASL) to investigate the hyperemic flow difference between major muscle groups in human extremities. Twenty-four healthy subjects with no evidence of vascular disease were recruited. MRI was conducted on a 3.0 Tesla Siemens Trio whole body system with a transmit/receive knee coil. A nonmagnetic orthopedic tourniquet system was used to create a 5-min period of ischemia followed by a period of hyperemic flow (occlusion pressure = 250 mmHg). CASL imaging, lasting from 2 min before cuff inflation to 3 min after cuff deflation, was performed on the midcalf, midfoot, and midforearm in separate sessions from which blood flow was quantified with an effective temporal resolution of 16 s. When muscles in the same anatomic location were compared, hyperemic flow was found to be significantly higher in the compartments containing muscles known to have relatively higher slow-twitch type I fiber compositions, such as the soleus muscle in the calf and the extensors in the forearm. In the foot, the plantar flexors exhibited a slightly delayed hyperemic response relative to that of the dorsal compartment, but no between-group flow difference was observed. These results demonstrate that CASL is sensitive to flow heterogeneity between diverse muscle groups and that nonuniform hyperemic flow patterns following an ischemic paradigm correlate with relative fiber-type predominance.
skeletal muscle; magnetic resonance imaging
Address for reprint requests and other correspondence: T. F. Floyd, Dept. of Anesthesiology and Critical Care, The Hospital of Univ. of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104 (e-mail: Thomas.Floyd{at}uphs.upenn.edu )
Abstract
Context
Studies of the possible cardiovascular risk of testosterone treatment are inconclusive.
Objective
To determine the effect of testosterone treatment on cardiovascular biomarkers in ...older men with low testosterone.
Design
Double-blind, placebo-controlled trial.
Setting
Twelve academic medical centers in the United States.
Participants
In all, 788 men ≥65 years old with an average of two serum testosterone levels <275 ng/dL who were enrolled in The Testosterone Trials.
Intervention
Testosterone gel, the dose adjusted to maintain the testosterone level in the normal range for young men, or placebo gel for 12 months.
Main Outcome Measures
Serum markers of cardiovascular risk, including lipids and markers of glucose metabolism, fibrinolysis, inflammation, and myocardial damage.
Results
Compared with placebo, testosterone treatment significantly decreased total cholesterol (adjusted mean difference, −6.1 mg/dL; P < 0.001), high-density lipoprotein cholesterol (adjusted mean difference, −2.0 mg/dL; P < 0.001), and low-density lipoprotein cholesterol (adjusted mean difference, −2.3 mg/dL; P = 0.051) from baseline to month 12. Testosterone also slightly but significantly decreased fasting insulin (adjusted mean difference, −1.7 µIU/mL; P = 0.02) and homeostatic model assessment‒insulin resistance (adjusted mean difference, −0.6; P = 0.03). Testosterone did not change triglycerides, d-dimer, C-reactive protein, interleukin 6, troponin, glucose, or hemoglobin A1c levels more than placebo.
Conclusions and Relevance
Testosterone treatment of 1 year in older men with low testosterone was associated with small reductions in cholesterol and insulin but not with other glucose markers, markers of inflammation or fibrinolysis, or troponin. The clinical importance of these findings is unclear and requires a larger trial of clinical outcomes.
Compared with placebo, testosterone treatment of older men with low testosterone was associated with small reductions in total, HDL, and LDL cholesterol and in insulin and HOMA-IR but not glucose.
The primary aim of the present study was to determine the cumulative effect of a set of peripheral artery disease (PAD) risk factors among age, gender and race/ethnicity groups in the United States.
...We examined data from a nationally representative sample of the US population (National Health and Nutrition Examination Survey NHANES, 1999-2004). A total of 7058 subjects 40 years or older that completed the interview, medical examination and had ankle-brachial index (ABI) measurements were included in this study.
The age- and sex-standardized prevalence of PAD was 4.6 % (standard error SE 0.3%).The highest prevalence of PAD was observed among elderly, non-Hispanic Blacks and women. In a multivariable age-, gender- and race/ethnicity-adjusted model hypertension, diabetes, chronic kidney disease, and smoking were retained as PAD risk factors (p ≤ 0.05 for each). The odds of PAD increased with each additional risk factor present from a non-significant 1.5-fold increase (O.R 1.5, 95% confidence interval CI 0.9-2.6) in the presence of one risk factor, to more than ten-fold (OR 10.2, 95% CI 6.4-16.3) in the presence of three or more risk factors. In stratified analysis, non-Hispanic Blacks (OR 14.7, 95% CI 2.1-104.1) and women (OR 18.6, 95% CI 7.1-48.7) were particularly sensitive to this cumulative effect.
In a large nationally representative sample, an aggregate set of risk factors that included diabetes mellitus, chronic kidney disease, hypertension and smoking significantly increase the likelihood of prevalent PAD. A cumulative risk factor analysis highlights important susceptibility differences among different population groups and provides additional evidence to redefine screening strategies in PAD.
We employed near-infrared optical techniques, diffuse correlation spectroscopy (DCS), and frequency-domain near-infrared spectroscopy (FD-NIRS) to test the hypothesis that supervised exercise ...training increases skeletal muscle microvascular blood flow and oxygen extraction in patients with peripheral artery disease (PAD) who experience claudication. PAD patients ( n = 64) were randomly assigned to exercise and control groups. Patients in the exercise group received 3 mo of supervised exercise training. Calf muscle blood flow and oxygen extraction were optically monitored before, during, and after performance of a graded treadmill protocol at baseline and at 3 mo in both groups. Additionally, measurements of the ankle-brachial index (ABI) and peak walking time (PWT) to maximal claudication were made during each patient visit. Supervised exercise training was found to increase the maximal calf muscle blood flow and oxygen extraction levels during treadmill exercise by 29% (13%, 50%) and 8% (1%, 12%), respectively P < 0.001; median (25th percentile, 75th percentile). These improvements across the exercise group population were significantly higher than corresponding changes in the control group ( P < 0.004). Exercise training also increased PWT by 49% (18%, 101%) ( P = 0.01). However, within statistical error, the ABI, resting calf muscle blood flow and oxygen extraction, and the recovery half-time for hemoglobin\myoglobin desaturation following cessation of maximal exercise were not altered by exercise training. The concurrent monitoring of both blood flow and oxygen extraction with the hybrid DCS/FD-NIRS instrument revealed enhanced muscle oxidative metabolism during physical activity from exercise training, which could be an underlying mechanism for the observed improvement in PWT. NEW & NOTEWORTHY We report on noninvasive optical measurements of skeletal muscle blood flow and oxygen extraction dynamics before/during/after treadmill exercise in peripheral artery disease patients who experience claudication. The measurements tracked the effects of a 3-mo supervised exercise training protocol and revealed that supervised exercise training improved patient ability to increase microvascular calf muscle blood flow and oxygen extraction during physical activity.
Cholesterol modification reduces cardiovascular events in patients with atherosclerosis, including those with peripheral arterial disease. The purpose of this study was to determine whether ...cholesterol lowering with atorvastatin improves walking performance in patients with intermittent claudication.
This randomized, double-blind, parallel-design study included 354 persons with claudication attributable to peripheral arterial disease. Patients were treated with placebo, atorvastatin (10 mg per day), or atorvastatin (80 mg per day) for 12 months. The outcome measures included change in treadmill exercise time and patient-reported measures of physical activity and quality of life based on questionnaires. Maximal walking time after 12 months of treatment with atorvastatin did not change significantly. However, there was improvement in pain-free walking time after 12 months of treatment for the 80-mg (P=0.025) group compared with placebo. A physical activity questionnaire demonstrated improvement in ambulatory ability for the 10- and 80-mg groups (P=0.011), whereas 2 quality of life instruments, the Walking Impairment Questionnaire and Short Form 36 Questionnaire, did not show significant change.
Atorvastatin improves pain-free walking distance and community-based physical activity in patients with intermittent claudication. When treated with atorvastatin, patients with peripheral arterial disease may experience improvement in symptoms to complement the anticipated reduction in cardiovascular events reported in other studies of statins.
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