Wennberg, Paul W.

Proximal claudication is secondary to ischemia caused by peripheral artery disease (PAD), whereas proximal pseudo-claudication is secondary to other disease processes such as hip arthritis, spinal stenosis, neuropathy, and so forth. The differentiation between the two can be challenging. Exercise transcutaneous oxygen pressure measurement (exercise-TcPO 2 ) allows noninvasive detection of flow-reducing lesions in the proximal arteries and tributaries of the lower extremity arterial tree. We present the first case report in the United States using an exercise-TcPO 2 algorithm. A 71-year-old diabetic patient with proximal left-sided and right-calf claudication with indeterminate ankle-brachial indices underwent an exercise-TcPO 2 study before and after endovascular intervention. Four TcPO 2 probes were placed: one at chest level (reference probe), one on each buttock, and one on the symptomatic calf. The Delta from Resting Oxygen Pressure (DROP) index was calculated at each probe site using a previously validated protocol. Proximal left- and right-calf ischemia were confirmed by the initial exercise-TcPO 2 , and, after endovascular treatment of the left iliac artery lesion, improvements in proximal exercise-TcPO 2 values were found. These data suggest that exercise-TcPO 2 can be useful in PAD evaluation in patients with non-compressible arteries and/or proximal claudication.

Background We investigated whether disease location influences survival in patients with peripheral arterial disease. Methods and Results Patients (n=12 731; mean age, 67.5±12.7 years; 57.4% male) who underwent outpatient noninvasive lower extremity arterial evaluation were followed up for 5.9±3.1 years for all‐cause mortality. Peripheral arterial disease (n=8930) was defined as a resting or postexercise ankle‐brachial index ( ABI ) ≤0.90, and normal ABI (n=3 801) was defined as a resting and postexercise ABI of 1.00 to 1.30. Presence or absence of disease at the proximal location or distal location was determined on the basis of D oppler signals in leg arteries; 42% had no PD or DD , 45% had proximal (14% postexercise PD only), 30% had distal disease, 17% had both proximal and distal disease, 28% had proximal only and 14% had distal only. We performed multivariable logistic regression to identify factors associated with disease location, and C ox proportional hazard regression to assess the respective effects of proximal or distal disease on survival. Older age, male sex, diabetes, heart failure, and critical limb ischemia were associated with distal disease, whereas female sex, smoking, hypertension, dyslipidemia, coronary heart disease, cerebrovascular disease, chronic obstructive pulmonary disease, and critical limb ischemia were associated with proximal disease. Over a mean follow‐up of 5.9±3.1 years, 3039 patients (23.9%) died. After adjustment for potential confounders, the hazard ratios ( HR s) of death associated with PD only and DD only were 1.3 (1.3 to 1.4) and 1.5 (1.4 to 1.6), respectively. After additional adjustment for resting ABI , there was no significant association between proximal disease and death, whereas the association of distal disease with death remained significant ( HR , 1.2; 95% CI , 1.1 to 1.3). Conclusions In patients with peripheral arterial disease, proximal and distal disease locations were associated with distinctive risk factor and comorbidity profiles. Distal disease was associated with worse survival even after adjustment for risk factors, comorbidities, and resting ABI .

Background —Endothelin-converting enzyme-1 (ECE-1) processes big endothelin-1 (ET-1) to ET-1, a peptide implicated in atheroma formation. ECE-1 exists in 2 isoforms (ECE-1α and ECE-1β), the result of alternative splicing of a common gene. Neutral endopeptidase (NEP) is a genetically distinct metallopeptidase that degrades the natriuretic peptides. These peptides mediate antiproliferative and vasodilating actions. We sought to demonstrate the distribution of the 2 ECE-1 isoforms in experimental atherosclerosis, to determine the effects of chronic NEP-I on plasma cGMP concentrations, vascular wall ECE-1 activity, and ET-1 concentration, and to correlate these actions with atheroma formation. Our hypothesis was that chronic NEP-I, in association with augmented cGMP, would inhibit ECE-1 conversion of big ET-1 to active ET-1, thus reducing tissue ET-1 concentrations and associated atheroma formation. Methods and Results —Cholesterol-fed New Zealand White rabbits (n=8, 1% cholesterol diet) and NEP-I–treated cholesterol-fed New Zealand White rabbits (n=8; candoxatril, 30 mg/kg per day, Pfizer) were euthanized after 8 weeks of feeding. ECE-1α and ECE-1β immunoreactivity was present in the aortas of both groups. Compared with control values, plasma cGMP concentrations were increased (2.8±0.6 versus 8.4±1.2 pmol/mL, P <0.05), ECE-1 activity was attenuated (68±3% versus 32±8%, P <0.05), aortic tissue ET-1 concentrations were reduced (4.6±0.5 versus 3.2±0.3 pg/mg protein, P <0.05), and atheroma formation was attenuated (62±6% versus 34±5%, P <0.01) by NEP-I. Conclusions —These studies suggest that ECE-1 is present and functionally active in the vascular wall in atherosclerosis. Inhibition of ECE-1 by NEP-I represents a novel approach to interruption of the endothelin system in this cardiovascular disease state.

Inferior vena cava (IVC) filters are widely used to decrease the risk of pulmonary embolism in patients with contraindications to anticoagulation. Complications include local hematoma, access site deep venous thrombosis (DVT), filter migration and embolization, leg penetration through the IVC wall, IVC occlusion, and filter fracture with embolization. Other rare complications include leg penetration into adjacent organs including duodenum and ureter. Lumbar artery pseudoaneurysms are rare and may be spontaneous, iatrogenic, or traumatic. To date, there have been 3 case reports of lumbar artery pseudoaneurysms caused by IVC filters. We present an additional case of a lumbar artery pseudoaneurysm caused by a Gunther Tulip IVC filter treated successfully with selective embolization.

External iliac artery endofibrosis describes an intimal subendothelial fibrosis leading to wall thickening and stenosis that has been described in high-performance athletes. There are anatomical, mechanical, and probably metabolic factors that may contribute to this pathology. Ankle–brachial index (ABI) measurement with exercise testing, duplex ultrasound, computed tomography (CT) or magnetic resonance (MR) angiogram, and ultimately arteriography help to make the diagnosis. Management can be conservative, but most cases require surgical intervention. External iliac vein stenosis and thrombosis in cyclists has rarely been described in the literature. We report a case of extensive left lower limb deep venous thrombosis (DVT) including the external iliac vein diagnosed in a 57-year-old athletic cyclist with a history of external iliac artery thrombosis.

Background With currently available effective interventional methods to treat superficial venous insufficiency, it becomes particularly important to have a simple and reliable method to evaluate the location and severity of venous reflux. To date, there are few studies that evaluated plethysmography with and without tourniquet application to differentiate superficial from deep venous incompetence. Objectives To determine if strain gauge plethysmography (SGP) with and without tourniquet application can be used to distinguish between the superficial and deep venous components of venous incompetence. Methods We conducted a prospective study using SGP with and without tourniquet application and duplex ultrasound (duplex US) to assess the severity and location of venous incompetence in 62 patients (85 limbs, 42 women, with an age range of 32–81 years) referred to our vascular laboratory for haemodynamic evaluation. Based on duplex US results, patients were diagnosed with superficial (SVI), deep and superficial (mixed) and deep vein incompetence (DVI). Results Mixed incompetence was the most common type. Twenty-three out of 33 limbs in the SVI group normalized their refill rate (RR) with tourniquet application (69.6%). Normalization of the RR with tourniquet application was less common in the mixed ( n: 17 out of 40, 42.5%) and DVI ( n: 2 out of 6, 33.3%) groups. Conclusion SGP with tourniquet application is a simple and fast technique that can identify patients with SVI, based on RR improvement, who probably would benefit more from ablation procedures. Further studies evaluating impact of SGP with tourniquet test results on clinical outcome of SVI invasive treatment are warranted