Are systolic velocity duplex metrics negatively affected by flow aliasing in areas of critical internal carotid artery stenosis.

: Duplex scanning is a useful noninvasive screening tool for the detection of carotid bifurcation disease. Internal carotid artery (ICA) peak systolic velocity (PSV) and ICA/common carotid artery (CCA) PSV ratios are proven metrics determining 70%-99% ICA stenosis. A potential disadvantage of using dramatically increasing systolic velocity measurements in areas of critical arterial stenosis is flow aliasing.

Duplex Criteria for Grading of External Carotid Stenosis.

Background: External carotid artery (ECA) stenosis is an independent mortality predictor. Additionally, concomitant ECA and internal carotid artery (ICA) stenosis progression has been associated with an increased risk of ipsilateral ischemic events in asymptomatic patients. Universally accepted ECA duplex velocity criteria, for the prediction of stenosis, do not exist.

Infrarenal rupture of an abdominal aortic aneurysm, previously repaired using an endoaneurysmorrhaphy technique.

Unusual as well as well-known complications can occur after aortic reconstruction. In an effort to heighten awareness of these possibilities, a case is presented of a 71-year-old male who was brought to the emergency department with severe back pain of 2 days duration and hypotension. He had undergone repair of an infrarenal abdominal aortic aneurysm 6 years earlier.

Gelatin-thrombin-based hemostatic sealant for intraoperative bleeding in vascular surgery.

Vascular surgical procedures may be prolonged because of intraoperative bleeding that is not easily controlled by cautery or suture ligation. This trial compared the ability of a new hemostat, FloSealTM Matrix (FM), with a known hemostat, Gelfoam(R) plus thrombin (GT), to control intraoperative bleeding. Patients undergoing vascular surgery procedures at four institutions were entered in the trial.

Transcutaneous oxygen measurements predict a beneficial response to hyperbaric oxygen therapy in patients with nonhealing wounds and critical limb ischemia.

Hyperbaric oxygen (HBO) therapy may be a useful adjunct in the treatment of patients with wounds associated with critical limb ischemia. These patients either cannot undergo a successful bypass or may not heal after vascular reconstruction alone. Identification of patients likely to benefit from HBO is essential before treatment, as this therapy is time-consuming, costly, and not without risk.

Supervised training of general surgery residents in carotid endarterectomy performed on awake patients under regional block is safe and desirable.

Previous studies have documented the safety and efficacy of general surgery residents and vascular fellows performing carotid endarterectomy (CEA) under the supervision of an attending surgeon. With the proper supervision of the attending surgeon, these operations can be performed with an acceptably low perioperative stroke and mortality rate. The question remains, however, whether these desirable results can be obtained by general surgery residents when operating on awake patients under regional block (RB) anesthesia.

Increased oxygen extraction as adaptation to acute renal ischemia.

Acute renal ischemia is an infrequently encountered clinical entity with occasionally devastating consequences. The renal compensation to acute ischemia is unknown and is the purpose of this report. Eight pigs were anesthetized and ventilated.

In-vitro assessment of the behavior of magnetic resonance angiography in the presence of constrictions.

Rationale And Objectives: Time-of-flight magnetic resonance angiography (TOF/MRA) is increasingly used to assess the nature and severity of stenotic blood vessels. Flow artifacts associated with high flows and/or narrow constrictions may confuse the interpretation of these studies. Accurate TOF/MRA evaluations demand an understanding of the nature of these flow effects.

Abnormalities in the biosynthesis of type III procollagen in cultured skin fibroblasts from two patients with multiple aneurysms.

We examined the synthesis of collagenous proteins by cultured skin fibroblasts taken from 14 patients with an abdominal aortic aneurysm and either an aneurysm at a second site (8 patients) or a first order relative with an abdominal aortic aneurysm (6 patients). Fibroblasts were labeled with [3H] proline and, following pepsin digestion of media proteins, the ratio of type I/III collagen was examined by denaturing polyacrylamide gel electrophoresis (SDS-PAGE). With the exception of two patients, the ratio of type I/III collagen in the media of fibroblasts from aneurysm patients was similar to control values (6 controls).

The comparative evaluation of three-dimensional magnetic resonance for carotid artery disease.

Conventional angiography is the current standard for the evaluation of carotid artery disease. The excellent resolution of this invasive study is offset by the potential for contrast-related, embolic, and puncture site complications. Three-dimensional magnetic resonance angiography may offer a noninvasive diagnostic alternative.

Hypertension sustains plaque progression despite reduction of hypercholesterolemia.

To assess the effect of hypertension on diet-induced coronary artery plaques after a return to a nonatherogenic diet, 10 cynomolgus monkeys were fed an induction regimen containing 2% cholesterol and 25% peanut oil for 6 months and then were subjected to midthoracic aortic coarctation to induce hypertension. The animals were then fed a nonatherogenic "prudent" ration for 6 additional months (hypertension-regression group). Twelve additional monkeys were fed the atherogenic diet for 6 months; six were killed (lesion-induction control group) and six were changed to the prudent diet for 6 additional months without coarctation (normotension-regression control group).

Interleaved magnetic resonance and ultrasound by electronic synchronization.

Increasing attention has been directed toward using magnetic resonance imaging (MRI) to assess blood flow velocity. Complete acceptance of this application requires validation of MRI-derived flow measurements against an accepted flow measurement technique such as Doppler ultrasound in an in vivo situation. To provide an accurate correlation in the presence of rapid changes in blood flow, the MR acquisition should be made nearly simultaneously with the ultrasonic measurements.

Can intraoperative prebypass arteriography substitute for the preoperative arteriogram?

Preoperative contrast arteriography is presently considered a requirement when planning infrainguinal arterial reconstructions in patients with limb-threatening ischemia. We reviewed the clinical data from 22 infrainguinal bypasses done in 20 patients to see if appropriate decisions concerning operability and the nature of the operation could be made from the physical examination and noninvasive data supplemented by a limited intraoperative on-table prebypass arteriogram. The presence of a normal femoral pulse with either a normal thigh pulse volume tracing or a normal high-thigh index assured adequate inflow to the groin level.

One hundred percent oxygen reverses muscle hypoxia in a rat hindlimb model of acute arterial occlusion.

Significant morbidity results from extremity ischemia after acute arterial occlusion. Reestablishment of arterial flow is considered to be the ideal treatment, yet substantial tissue loss can occur before this is accomplished. Using a rat hindlimb model we investigated whether the administration of 100% oxygen would decrease tissue hypoxia from acute arterial occlusion.

Magnetic resonance imaging of acute occlusive intestinal ischemia.

The mortality of acute superior mesenteric artery occlusion and mesenteric infarction remains high, in part because of the failure to identify the patients with the disorder. A reliable noninvasive diagnostic study may facilitate earlier definitive diagnosis and therapy. Proton magnetic resonance imaging may offer a noninvasive diagnostic alternative.

Catheter occlusion of a mycotic renal artery aneurysm with cure of associated renovascular hypertension.

We describe successful transcatheter occlusion of a mycotic renal artery aneurysm. The patient's hypertension resolved following occlusion of the aneurysm and infarction of the renal parenchyma in the distribution of the aneurysmal vessel.

Shear stress regulation of artery lumen diameter in experimental atherogenesis.

We studied the adaptive response of the arterial wall and intimal thickening under conditions of increased flow in an atherogenic model. Blood flow was increased by construction of an arteriovenous fistula between the right iliac artery and vein in six cynomolgus monkeys fed a diet containing 2% cholesterol and 25% peanut oil. The left iliac artery served as the control.

31P nuclear magnetic resonance spectroscopy: noninvasive biochemical analysis of the ischemic extremity.

The biochemical effects of peripheral vascular disease on skeletal muscle have not been characterized precisely because of the lack of satisfactory noninvasive analytic methods. 31P nuclear magnetic resonance (NMR) spectroscopy was used to measure the high-energy phosphate compounds, phosphocreatine (PCr) and adenosine triphosphate, as well as metabolic byproducts, such as inorganic phosphates (Pi) and phosphate monoesters in calf muscles of 214 limbs with peripheral vascular disease. Intracellular pH was also measured.

Increased collagenase activity in early aneurysmal dilatation.

Increased collagenase activity has been implicated as a basic abnormality in aortic aneurysm formation. We studied a localized aneurysmal change, poststenotic dilatation, and its relation to collagenase and elastase activity of the aortic wall. Cynomolgus monkeys underwent midthoracic aortic coarctation to produce poststenotic dilatation.

Role of medial lamellar architecture in the pathogenesis of aortic aneurysms.

The human abdominal aorta is particularly susceptible to the formation of aneurysms with atrophic walls. This aortic segment normally has fewer medial lamellar units than would be expected for a mammalian aorta of comparable diameter as well as far fewer medial vasa vasorum than would be expected for an aortic wall of comparable thickness. To test the hypothesis that ischemia and/or loss of normal lamellar architecture are predisposing factors for aneurysm formation, we used the pig thoracic aorta, which is furnished with 75 medial layers and vasa supplying the outer two thirds.