Noninvasive vascular laboratory for evaluation of peripheral arterial occlusive disease: Part II--clinical applications: chronic, usually atherosclerotic, lower extremity ischemia

Interpretation of peripheral arterial and venous Doppler waveforms: A consensus statement from the Society for Vascular Medicine and Society for Vascular Ultrasound

This expert consensus statement on the interpretation of peripheral arterial and venous spectral Doppler waveforms was jointly commissioned by the Society for Vascular Medicine (SVM) and the Society for Vascular Ultrasound (SVU). The consensus statement proposes a standardized nomenclature for arterial and venous spectral Doppler waveforms using a framework of key major descriptors and additional modifier terms. These key major descriptors and additional modifier terms are presented alongside representative Doppler waveforms, and nomenclature tables provide context by listing previous alternate terms to be replaced by the new major descriptors and modifiers. Finally, the document reviews Doppler waveform alterations with physiologic changes and disease states, provides optimization techniques for waveform acquisition and display, and provides practical guidance for incorporating the proposed nomenclature into the final interpretation report.

The importance of community screening of asymptomatic elderly for peripheral arterial disease by Doppler ultrasound and ankle-brachial index

Background

Peripheral arterial disease is an atherosclerotic disease characterized by an increase in morbidity and mortality. For these reasons early diagnosis of peripheral arterial disease is important. Ankle-brachial systolic pressure index measurement is frequently used in screening studies. Evaluating waveforms of distal lower extremities with Doppler ultrasound can be used as a screening program and provides more accurate information on peripheral arterial disease.

Aim

We investigate the prevalence of peripheral arterial disease, compare the efficacy of Doppler ultrasound evaluation of distal lower extremity waveforms and ankle-brachial systolic pressure index measurement in screening programs, and discuss the importance of early diagnosis of asymptomatic cases.

Material and methods

A total of 457 patients over the age of 65 (between 65 and 94, mean age: 71.4) including 270 males and 187 females were examined with Doppler ultrasound, had ankle-brachial systolic pressure index measurement taken and were screened for peripheral arterial disease. The correlation between Doppler ultrasound findings and ankle-brachial systolic pressure index was examined.

Results

According to the Doppler ultrasound findings, in the aortoiliac (r = 0.648) and femoropopliteal (r = 0.564) area, there is a medium level of correlation between severe stenosis and occlusions and a low ankle-brachial systolic pressure index value, and a low level of correlation between such abnormalities in the tibioperoneal region (r = 0.116) and a low ankle-brachial systolic pressure index value. Therefore, while the sensitivity of ankle-brachial systolic pressure index increases in proximal stenosis, it decreases in distal stenosis.

Conclusion

Despite the fact that ankle-brachial systolic pressure index is a diagnostic test commonly used in screening studies, evaluation of distal arteries by means of Doppler ultrasound provides more accurate information in terms of the identification of peripheral arterial disease.

Peripheral arterial disease

Peripheral arterial disease of the lower extremities is a common manifestation of the atherosclerotic process. A heightened awareness of symptomatic and asymptomatic disease, as well as screening of at-risk patients, is imperative because of the increased risk of cardiovascular disease, cerebrovascular disease, and even death. This article describes the various symptoms, diagnostic tests, and therapies for this common, underdiagnosed, undertreated disease.

Contrast-enhanced ultrasound evaluation of peripheral microcirculation in diabetic patients: effects of cigarette smoking

PURPOSE

Cigarette smoking and diabetes mellitus predisposes to vascular disease. Our study aimed to evaluate the chronic effects of cigarette smoking on peripheral microcirculation assessed with contrast-enhanced ultrasound (CEUS) in diabetic patients.

MATERIALS AND METHODS

The study population comprised ten smoker (7/3 M/W, age 42-76 years) and 16 nonsmoker (8/8 men/women, age 47-80 years) diabetic patients. The ankle-brachial index (ABI) was determined, and colour Doppler ultrasound (CDUS) of the lower legs was performed to determine the presence of peripheral arteriopathy disease (PAD). Microvascular blood flow in the gastrocnemius muscle was evaluated with CEUS.

RESULTS

No differences were observed in ABI and CDUS examination between smokers and nonsmokers. Smoking had a significant effect on microcirculatory function. Timeto-peak (TTP), arrival time in tissue (ATt) and artery/ tissue transit time (A/Ttt) were significantly prolonged in smokers (TTP 43.76 ± 9.38 s vs. 34.12 ± 6.8 s, p=0.011, ATt 28.9 ± 7.5s vs. 22.4 ± 6.4 s, p=0.017 and A/Ttt 6.81 ± 4.52 s vs. 3.25 ± 3.27 s, p=0.02), with no significant differences between patients with and without PAD.

CONCLUSIONS

The long-term exposure to cigarette smoke affects microcirculatory function. Contrast imaging is a noninvasive technique that can document these effects.

Medical and endovascular management of critical limb ischemia

Critical limb ischemia (CLI) is the term used to designate the condition in which peripheral artery disease has resulted in resting leg or foot pain or in a breakdown of the skin of the leg or foot, causing ulcers or tissue loss. If not revascularized, CLI patients are at risk for limb loss and for potentially fatal complications from the progression of gangrene and the development of sepsis. The management of CLI requires a multidisciplinary team of experts in different areas of vascular disease, from atherosclerotic risk factor management to imaging, from intervention to wound care and physical therapy. In the past decade, the most significant change in the treatment of CLI has been the increasing tendency to shift from bypass surgery to less invasive endovascular procedures as first-choice revascularization techniques, with bypass surgery then reserved as backup if appropriate. The goals of intervention for CLI include the restoration of pulsatile, inline flow to the foot to assist wound healing, the relief of rest pain, the avoidance of major amputation, preservation of mobility, and improvement of patient function and quality of life. The evaluating physician should be fully aware of all revascularization options in order to select the most appropriate intervention or combination of interventions, while taking into consideration the goals of therapy, risk-benefit ratios, patient comorbidities, and life expectancy. We discuss the incidence, risk factors, and prognosis of CLI and the clinical presentation, diagnosis, available imaging modalities, and medical management (including pain and ulcer care, pharmaceutical options, and molecular therapies targeting angiogenesis). The endovascular approaches that we review include percutaneous transluminal angioplasty (with or without adjunctive stenting); subintimal angioplasty; primary femoropopliteal and infrapopliteal deployment of bare nitinol, covered, drug-eluting, or bioabsorbable stents; cryoplasty; excimer laser-assisted angioplasty; excisional atherectomy; and cutting balloon angioplasty.

Nonenhanced MR angiography

While nonenhanced magnetic resonance (MR) angiographic methods have been available since the earliest days of MR imaging, prolonged acquisition times and image artifacts have generally limited their use in favor of gadolinium-enhanced MR angiographic techniques. However, the combination of recent technical advances and new concerns about the safety of gadolinium-based contrast agents has spurred a resurgence of interest in methods that do not require exogenous contrast material. After a review of basic considerations in vascular imaging, the established methods for nonenhanced MR angiographic techniques, such as time of flight and phase contrast, are considered and their advantages and disadvantages are discussed. This article then focuses on new techniques that are becoming commercially available, such as electrocardiographically gated partial-Fourier fast spin-echo methods and balanced steady-state free precession imaging both with and without arterial spin labeling. Challenges facing these methods and possible solutions are considered. Since different imaging techniques rely on different mechanisms of image contrast, recommendations are offered for which strategies may work best for specific angiographic applications. Developments on the horizon include techniques that provide time-resolved imaging for assessment of flow dynamics by using nonenhanced approaches.

Limb stress-rest perfusion imaging with contrast ultrasound for the assessment of peripheral arterial disease severity

OBJECTIVES

We hypothesized that stress-rest perfusion imaging of skeletal muscle in the lower extremity with contrast-enhanced ultrasound (CEU) could evaluate the severity of peripheral arterial disease (PAD).

BACKGROUND

Perfusion imaging may provide valuable quantitative information on PAD, particularly in patients with diabetes in whom microvascular functional abnormalities are common.

METHODS

Study subjects included 26 control subjects and 39 patients with symptomatic PAD, 19 of whom had type 2 diabetes mellitus. A modified treadmill exercise test was performed to determine exercise time to development of claudication. Multilevel pulse-volume recordings and ankle-brachial index (ABI) at rest and post-exercise ABI were measured in both extremities. Microvascular blood flow in the gastrocnemius and soleus muscles was measured at rest and after 2 min of calibrated plantar-flexion exercise.

RESULTS

During exercise, claudication did not occur in normal subjects and occurred earlier in PAD patients with diabetes than without (median time 1.2 min [95% confidence interval (CI) 0.6 to 2.5] vs. 3.0 min [95% CI 2.1 to 6.0], p < 0.01). Compared to control subjects, patients with PAD had lower skeletal muscle blood flow during plantar-flexion exercise and lower flow reserve on CEU. After adjusting for diabetes, the only diagnostic tests that predicted severity of disease by claudication threshold were CEU exercise blood flow and flow reserve (odds ratios 0.67 [95% CI 0.51 to 0.88; p = 0.003] and 0.64 [95% CI 0.46 to 0.89, p = 0.008], respectively). A quasi-likelihood information analysis incorporating all non-invasive diagnostic tests indicated that the best models for predicting severity of disease were the combination of diabetes and either exercise blood flow or flow-reserve on CEU.

CONCLUSIONS

Perfusion imaging of limb skeletal during exercise and measurement of absolute flow reserve can provide valuable information on the severity PAD. This strategy may be useful for evaluating the total impact of disease in patients with complex disease or those with coexisting functional abnormalities of flow regulation.

Peripheral arterial disease: diagnosis, treatment, and systemic implications

Peripheral arterial disease is common in adults and is found in many patients with lower extremity ulcers. It is important to diagnose peripheral arterial disease not only because of its impact on the involved lower extremity but also because it often occurs with atherosclerotic disease in other vascular beds. Although patient symptoms may be helpful in the diagnosis, most afflicted patients either are asymptomatic or have atypical symptoms. Physical examination, an ankle-brachial index, referral to a noninvasive vascular laboratory, contrast angiography, and magnetic resonance angiography can be helpful diagnostically. Beneficial therapies include smoking cessation, exercise therapy, cholesterol reduction, antiplatelet therapy, and treatment of hypertension and diabetes. For patients with symptomatic claudication, cilostazol can be considered. Patients with nonhealing ulcers, rest pain, or severe claudication should be referred for interventions.

A Prospective Cohort Study of Lower-Extremity Pressure Ulcer Risk Among Bedfast Older Adults

OBJECTIVE

To estimate the incidence and identify risk factors for lower-extremity pressure ulcers in bedfast older adult patients.

DESIGN

Prospective cohort study.

SETTING

A 500-bed long-term-care facility in Japan.

PATIENTS

A total of 259 patients who were aged 65 years or older, confined to bed, and without lower-extremity pressure ulcers at enrollment participated in the study.

MAIN OUTCOME MEASURES

Incidence of occurrence, wound characteristics, and risk factors for lower-extremity pressure ulcers. The incidence of lower-extremity pressure ulcers per 100 person-years was 16.8 (n = 33). The most common sites of lesions were the toes and heels. Cox regression analysis indicated that 3 factors were independently related to new lower-extremity pressure ulcer risk: low ankle-brachial index value (hazards ratio 0.075; 95% confidence interval [CI], 0.023-0.242), length of bedfast period (hazards ratio 1.010; 95% CI, 1.004-1.015), and male gender (hazards ratio 2.951; 95% CI, 1.450-6.009). Receiver operating characteristic curve analysis showed the area under the curve was 0.760 (95% CI, 0.675-0.844) for the ankle-brachial index. Therefore, an ankle-brachial index cutoff level of 0.8 provided high sensitivity and adequate specificity.

CONCLUSION

Lower-extremity pressure ulcers are a significant problem in bedfast older adult patients aged 65 years or older. Bedfast older adult patients who developed lower-extremity pressure ulcers in this study were believed to have arteriosclerosis; the patients' ulcers exhibited features of ischemic ulcers. The findings of the present study suggest that bedfast older adult patients with a low ankle-brachial index value, a long bedfast period, or male gender should be closely monitored for lower-extremity pressure ulcer development on admission to long-term-care facilities. In particular, the ankle-brachial index is recommended as a screening tool in this practice setting.

Intermittent claudication: an overview

Intermittent claudication (IC) is defined by leg muscle pain, cramping and fatigue brought on by ambulation/exercise; relieved on rest; and caused by inadequate blood supply and is the primary symptom of peripheral arterial disease (PAD). PAD has a detrimental effect on the quality of life. PAD is a debilitating atherosclerotic disease of the lower limbs and is associated with an increased risk of cardiovascular morbidity and mortality. IC is an extremely important marker of atheroma. Up to 60% patients with IC have significant underlying coronary and/or carotid disease and 40% of all patients suffering from IC die or suffer a stroke within 5 years of presentation. The therapeutic intervention of IC essentially aims at providing symptomatic relief and reducing the systemic cardiovascular complications. Although exercise therapy is one of the most efficacious conservative treatments for claudication, the pharmacotherapeutic goals can be best achieved through an increase in the walking capacity to improve quality of life and a decrease in rates of amputation. In the development of treatment for IC, an aggressive non-pharmacological intervention and pharmacological treatment of the risk factors associated with IC are considered. In the next 2 years, the results of major trials of drugs that stabilize and regress atherosclerosis such as statins and angiotensin converting enzyme inhibitors, and anti-platelet agents, recombinant growth factors and immune modulators will be available for IC. Levocarnitine (l-carnitine) and a derivative, propionyl levocarnitine, are emerging agents that increase the pain-free walking and improve the quality of life in IC patients by working at the metabolism and exercise performance of ischemic muscles. This article provides a comprehensive review of the pathophysiology involved, diagnosis of IC and existing and emerging pharmacotherapies with rationale for their use in its treatment.

Ultrasonographic Modalities to Assess Vascular Anatomy and Disease

Medical ultrasound (US) encompasses a family of imaging techniques linked by the use of high-frequency sound waves, typically 2.5-10 million cycles per second (MHz), to interrogate tissue. Although similar, each imaging technique has relatively distinct features and may provide unique information. This review is designed to provide vascular and interventional radiologists with an in-depth understanding of each US imaging technique and relevant physics principles to assist in optimizing the US examination so that the specific vascular anatomy and disease states in question can be comprehensively understood. This review will be limited to principles of transcutaneous US and will not include specific techniques for assessment of individual vessels (except for illustrative purposes) or methods to optimize US scan parameters.