Vascular age to determine cardiovascular disease risk: A systematic review of its concepts, definitions, and clinical applications.

BACKGROUND: Vascular age is an alternate means of representing an individual's cardiovascular risk. Little consensus exists on what vascular age represents and its clinical utility has not been determined. We systematically reviewed the literature to provide a comprehensive overview of different methods that have been used to define vascular age, and to examine its potential clinical value in patient communication and risk prediction. DESIGN: This was a systematic review with data sources of PubMed and Embase. RESULTS: We identified 39 articles on vascular age, 20 proposed to use vascular age as a communication tool and 19 proposed to use vascular age as a means to improve cardiovascular risk prediction. Eight papers were methodological and 31 papers reported on vascular age in study populations. Of these 31 papers, vascular age was a direct translation of the absolute risk estimated by existing cardiovascular risk prediction models in 15 papers, 12 derived vascular age from the reference values of an additional test, and in three papers vascular age was defined as the age at which the estimated cardiovascular risk equals the risk from non-invasive imaging observed degree of atherosclerosis. One trial found a small effect on risk factor levels when vascular age was communicated instead of cardiovascular risk. CONCLUSION: Despite sharing a common name, various studies have proposed distinct ways to define and measure vascular age. Studies into the effects of vascular age as a tool to improve cardiovascular risk prediction or patient communication are scarce but will be required before its clinical use can be justified.

The role of comorbidity in the assessment of intermittent claudication in older adults.

The prevalence of intermittent claudication (IC) in older adults by questionnaire is less than 5% while the prevalence of peripheral arterial disease (PAD) by non-invasive testing is 2-4-fold higher. Comorbid conditions may result in under-reporting intermittent claudication (IC) as assessed by the Rose Questionnaire. We examined characteristics of those who report leg pain in relationship to other comorbid conditions and disability in 5888 participants of the Cardiovascular Health Study (CHS). Older adults with exertional leg pain, not meeting criteria for IC, had a higher prevalence of PAD on non-invasive testing with the ankle-arm index than those without pain, as well as a higher prevalence of arthritis. The pattern of responses suggested that pain for both conditions was reported together. The Rose Questionnaire for IC is specific for PAD, but a negative questionnaire does not indicate a lack of symptoms, rather the presence of PAD along with other conditions that can cause pain.

MR assessment of the extremity veins.

This article provides an overview of the technique of magnetic resonance venography (MRV) and its relative value in the diagnostic work-up of suspected lower or upper extremity venous thrombosis. MRV is accurate for diagnosis or exclusion of deep vein thrombosis. MRV should be considered complimentary, in many instances, to the less expensive modality of venous sonography. It is the complimentary use of magnetic resonance techniques at the level of the pelvis and the mediastinum that offers the greatest cost benefit as part of an incremental strategy for the work-up of patients presenting with lower or upper extremity swelling.

Non-invasive assessment of brachial artery endothelial vasomotor function: the effect of cuff position on level of discomfort and vasomotor responses.

Non-invasive assessment of brachial artery flow-mediated dilation using cuff occlusion of the arm above or below the elbow to stimulate flow is emerging as a highly useful technique to examine endothelial vasomotor function in human subjects. In anticipation of a large-scale investigation, an important issue is the acceptability of the technique to participants. The purpose of this study was to determine the level of discomfort associated with the technique and compare it to the commonly used procedure of venipuncture. Flow-mediated dilation was determined using cuff occlusion of the arm above the elbow and a blood sample was obtained by standard venipuncture from 54 subjects. The level of discomfort for each procedure was assessed and compared using a visual analogue scale and was found to be extremely low. When the occlusion cuff was positioned above the elbow, the discomfort was slightly more severe (1.9+/-1.9 cm) than venipuncture (1.0+/-1.3 cm, p = 0.003). In 27 subjects, the effect of cuff position (above or below the elbow) was compared: the below the elbow position was associated with a reduction in the percentage increase in flow (570+/-280% versus 900+/-560%, p = 0.005), flow-mediated dilation (6.8+/-3.8% versus 9.8+/-5.7%, p = 0.008) and discomfort (1.6+/-0.8 versus 3.7+/-2.2 cm, p = 0.008). When the cuff was located below the elbow, the level of discomfort was equivalent to that associated with venipuncture. Thus, non-invasive assessment of flow-mediated brachial artery dilation is well tolerated and appears to be suitable for a large-scale study of endothelial function.

Noninvasive assessment of endothelium-dependent flow-mediated dilation of the brachial artery.

Coronary atherosclerosis is characterized by an early loss of endothelium-dependent vasodilation. However, the methods of assessing coronary endothelial function are invasive and difficult to repeat over time. Recently, a noninvasive ultrasound method has been widely used to measure flow-mediated dilation in the brachial artery as a surrogate test for endothelial function. We seek to further validate this method of measuring vascular function. The brachial artery diameters and blood flow of 20 normal volunteers (10 males and 10 females) were measured using high resolution (7.5 MHz) ultrasound and strain gauge plethysmography. Flow-mediated endothelium-dependent vasodilation was measured in the brachial artery during reactive hyperemia after 5 minutes of cuff occlusion in the upper arm. The brachial artery diameter increased maximally by 9.7 +/- 4.3% from baseline at 1 min after cuff release and blood flow increased by 1002 +/- 376%. Five min of cuff occlusion was sufficient to achieve 97 +/- 6% of maximal brachial artery dilation and degree of dilation was not different whether the cuff was inflated proximally or distally to the image site. The intraobserver variability in measuring brachial diameters was 2.9% and the variability of the hyperemic response was 1.4%. In young, healthy men and women, the baseline brachial artery diameter was the only factor that was predictive of the flow-mediated vasodilation response. The brachial noninvasive technique has been further validated by the determination of flow-mediated dilation. This method of assessing endothelial function may help to determine the importance of vasodilator dysfunction as a risk factor in the development of atherosclerosis.

Preoperative assessment of the carotid bifurcation. Can magnetic resonance angiography and duplex ultrasonography replace contrast arteriography?

BACKGROUND AND PURPOSE: Noninvasive studies are used with increasing frequency to assess the carotid bifurcation before endarterectomy. Therefore, assessment of their diagnostic accuracies is essential for appropriate patient management. We prospectively evaluate two noninvasive tests, magnetic resonance angiography (MRA) and duplex ultrasonography (DU), as potential replacements for contrast arteriography (CA). METHODS: A blinded comparison of three-dimensional time-of-flight (TOF) MRA, two-dimensional TOF MRA, and DU in 176 arteries was performed. CA was used as the standard of comparison. RESULTS: Three-dimensional TOF MRA had a sensitivity of 94%, a specificity of 85%, and an accuracy of 88% for the identification of 70% to 99% stenosis; two-dimensional TOF MRA had a sensitivity and specificity that were approximately 10% lower than those of three-dimensional TOF MRA. DU resulted in a sensitivity of 94%, a specificity of 83%, and an accuracy of 86%. Combining data from three-dimensional TOF MRA and DU, allowing for CA only for disparate results, yielded a sensitivity of 100%, a specificity of 91%, and an accuracy of 94% among concordant noninvasive tests, with CA required in 16% of arteries. MRA accurately differentiated 17 carotid occlusions from 16 high-grade (90% to 99%) stenoses, whereas with DU two patent arteries were identified as occluded and one occluded artery was identified as patent. CONCLUSIONS: Three-dimensional TOF MRA is the most accurate noninvasive test. Combined use of MRA and DU results in a marked increase in accuracy to a level that obviates the need for CA in a majority of patients.

Perioperative imaging strategies for carotid endarterectomy. An analysis of morbidity and cost-effectiveness in symptomatic patients.

OBJECTIVE: To assess the cost-effectiveness of four diagnostic strategies for the preoperative evaluation of symptomatic patients who are potential candidates for carotid endarterectomy (ie, 70% to 99% stenosis): (1) duplex sonography (DS), (2) magnetic resonance angiography (MRA), (3) contrast angiography (CA), and (4) the combination of DS and MRA supplemented by CA for disparate results. METHODS: Cost-effectiveness analysis based largely on published clinical trial data. Sensitivities and specificities of noninvasive tests were estimated from 81 patients undergoing prospective evaluation with DS, MRA, and CA. OUTCOME MEASURE: Incremental cost per quality-adjusted year of life gained. RESULTS: For a hypothetical cohort of symptomatic patients undergoing evaluation for carotid endarterectomy, the combination of tests resulted in the greatest quality-adjusted life expectancy of the four options considered. After incorporating the costs of testing, surgery, and stroke, we found that neither the MRA nor the CA strategy was cost-effective. The combination of tests was more effective but more costly than DS, resulting in an additional cost of $22,400 per quality-adjusted year of life gained. For centers that do not have adequate MRA, CA resulted in an additional cost of $99,200 per quality-adjusted year of life saved compared with DS. CONCLUSIONS: Our results suggest that for the preoperative detection of a 70% to 99% carotid stenosis, the combination of DS and MRA, supplemented by CA for disparate results, is associated with the lowest long-term morbidity and mortality and has a favorable cost-effectiveness ratio. The combination of tests, or DS alone when MRA is not available, could potentially replace the current practice of using CA alone in the preoperative evaluation of patients with symptomatic carotid stenosis.

Temporal patterns of antihypertensive medication use among elderly patients. The Cardiovascular Health Study.

OBJECTIVES: To estimate the incidence of newly treated hypertension and to describe the patterns of antihypertensive medication use among those aged 65 years and older. DESIGN: Medicare eligibility lists from four US communities (Forsyth County, North Carolina; Washington County, Maryland; Sacramento County, California; and Pittsburgh, Pa) were used to obtain a representative sample of 5201 community-dwelling elderly for the Cardiovascular Health Study, a prospective cohort study of risk factors for coronary heart disease and stroke. Participants were examined at baseline and again 1 year later. The two examinations included standardized questionnaires, blood pressure measurements, and the assessment of medication use by medication inventory. In this cohort analysis, we excluded 231 subjects (4.4%) who did not return for follow-up, 69 (1.3%) who had missing data for medications, and another 495 (9.5%) who were taking "antihypertensive" medications for an indication other than high blood pressure. INTERVENTIONS: None. RESULTS: Among the 4406 participants, 1613 used antihypertensive medications at both visits. Between the two visits, 144 started and 115 stopped antihypertensive therapy. Among nonusers at baseline, the annual incidence of newly treated hypertension was 5.2% in women and 5.6% in men. Due to the number of participants who stopped therapy, the overall prevalence of antihypertensive treatment increased only slightly, from 40.7% to 41.1% in women and from 37.1% to 38.2% in men, during 1 year of follow-up. After adjustment for age, systolic blood pressure, number of antihypertensive drugs, diabetes, and cardiovascular disease, the newly treated hypertensives were about half as likely as the previously treated hypertensives to receive diuretics (odds ratio [OR], 0.59; P = .008) or beta-blockers (OR, 0.52; P = .01); and they were about twice as likely to receive calcium channel blockers (OR, 1.88; P < .004) or angiotensin converting enzyme inhibitors (OR, 2.40; P < .001). A similar pattern of within-person changes over time was apparent among the continuous users. CONCLUSIONS: Between June 1990 and June 1991, physicians were increasingly prescribing angiotensin converting enzyme inhibitors and calcium channel blockers in place of diuretics and beta-blockers for the treatment of hypertension in elderly patients, especially for those just starting therapy.

Deep veins of the calf: assessment with color Doppler flow imaging.

The authors studied the ability of real-time ultrasound aided by color Doppler flow imaging to demonstrate the deep veins of the calf in ten healthy subjects and 49 patients (91 limbs) with suspected deep venous thrombosis. Posterior tibial and peroneal veins demonstrated flow accentuation in 98% (74 of 75) and 96% (72 of 75), respectively, of the limbs without thrombosis and in all 20 normal limbs. Sixteen legs were involved with deep venous thrombosis. Peroneal veins could not be seen in three legs with marked calf swelling due to proximal thrombosis. There were two cases of thrombosis limited to the calf, nine of popliteal thrombosis (seven with contiguous spread of thrombus), and five of thrombosis limited to above the knee (four with sparing of the deep veins of the calf). Visualization of anterior tibial veins, achieved in 65% of all legs, did not correlate with thrombosis. The authors conclude that color Doppler flow imaging can demonstrate patency of posterior tibial and peroneal veins in most patients without deep venous thrombosis and aid in detection of below-the-knee thrombosis.