Validation of flow convergence region method in the assessment of carotid artery stenoses during color-flow duplex studies.

PURPOSE: The flow convergence region (FCR) method (also known as the proximal isovelocity surface area method) is currently used in echocardiography to evaluate the flow through cardiac valves and septal defects. The FCR method is based on the characteristic alterations in flow dynamics that occur proximal to a stenotic orifice. Blood converges uniformly and radially towards an orifice that is small relative to the section of the vessel and forms concentric isovelocity hemispheric shells where velocity progressively increases and flow remains laminar. The purpose of the article is to validate the use of this principle in the detection and assessment of carotid stenoses in the course of color-flow duplex studies. METHODS: In this prospective study, 80 patients affected by unilateral or bilateral carotid artery stenoses were evaluated for the presence of the FCR from February 1997 to March 1999. The results were compared with digital subtraction angiography. RESULTS: Color-flow duplex diagnosis of carotid artery stenoses of 70% or more was confirmed in 100% of the carotid artery stenoses (40/40 patients) with angiography. The FCR was detected in 72.2% (13/18) of carotid arteries affected by stenoses greater than 80%, in 54.4% (12/22) of carotid arteries affected by stenoses 70% to 80%, and in 13.6% (6/44) of carotid arteries affected by stenoses 50% to 69% (P <.001). In 5% of cases (2/40 of stenoses) the FCR was the only detectable sign of carotid stenosis. CONCLUSION: Our data suggest that a routine search for FCR in the course of color-flow duplex study of carotid arteries may further improve the reliability of this examination in the detection of carotid artery stenoses, particularly in the presence of heavily calcified lesions.

"Marsupial cava" and ruptured abdominal aortic aneurysm. A case report and review of the literature.

A patient with a ruptured abdominal aortic aneurysm underwent an emergency operation. A rare anomaly of inferior vena cava, known as "marsupial cava," was found. The iliac vein confluence crossed anteriorly (rather then posteriorly) the right common iliac artery. Even though the patient had undergone a computed tomography scan, this rare anomaly had not been detected and therefore was unexpected by the surgeon. The aim of this report is to describe the technical details required to perform the aortic reconstruction and to stress the importance of routine computed tomography scans and their careful reading in the case of stable patients before retroperitoneal operation. This is, to our knowledge, the first report of an aortic prosthetic grafting for ruptured aortic aneurysm in association with a marsupial cava.

[The role of transplanted vein graft in arterial reconstruction]. / Il ruolo dell'innesto con vena traslocata nella ricostruzione arteriosa.

The use of the non-reversed saphenous vein has not been properly evaluated yet, for what concerns the features of length and application. In the reported series this technique has been employed for the reconstruction of arterial segments in various anatomic sites. The mean follow-up was 10 months. Between November 1987 and September 1993 at the Department of Vascular Surgery of Pietra Ligure and Imperia 39 arterial grafts with the use of non-reversed autologous saphenous vein were performed, for the treatment of arteriosclerotic, traumatic or aneurysmatic diseases. On the basis of the outcomes (70 to 100% patency of the grafts found at the follow-up), pro and cons of this technique is weighed up and some guidelines about the procedure of choice (among the non-reversed, in situ or reversed saphenous vein) are settled, keeping in mind the different variations who must influence and direct the surgeons' choice (venous diameter, features of the site to revascularize etc.).

Bovine fast-twitch myosin light chain 1: cloning and mRNA amount in muscle of cattle treated with clenbuterol.

The cDNA clone encoding the fast-twitch isoform of myosin light chain 1 (MLC-1f) was isolated from bovine longissimus dorsi muscle and sequenced in M13 and pUC8. An 0.8-kb subclone, produced by digestion of the cDNA with EcoRI, contained the portion of the molecule common to MLC-1f and MLC-3f. The cDNA in pUC8 contained an additional 81 bp upstream of the EcoR I digestion site, which was unique to MLC-1f. The cDNA clone was used to measure MLC-1f mRNA in longissimus dorsi muscle of cattle chronically administered the beta-adrenergic agonist clenbuterol. Treatment with clenbuterol for 50 days increased succinic dehydrogenase negative (type IIB) and positive (types I and IIA) myofiber cross-sectional areas by 25%. After the 50-day treatment period, the amount of MLC-1f mRNA was 90% greater in longissimus dorsi muscle of treated animals than in the initial group. This effect was lost when clenbuterol treatment was withdrawn for a 78-day period, during which time muscle growth in the treated animals stopped completely. We conclude that we have cloned the bovine cDNA for MLC-1f, which has provided additional evidence that beta-adrenergic agonists increase myofibrillar gene expression.

Adipose tissue cellularity and muscle growth in young steers fed the beta-adrenergic agonist clenbuterol for 50 days and after 78 days of withdrawal.

Angus steers (n = 40; approximate weight = 300 kg) were administered the beta-adrenergic agonist clenbuterol for 50 d (7 mg.hd-1.d-1), followed by a 78-d withdrawal period. Carcass fatness variables did not differ (P greater than .05) between treated and control animals either after 50 d or after 128 d. Weights of the 9-10-11th rib longissimus muscle were 25% larger, and longissimus cross-sectional areas were 28% greater, in clenbuterol-fed steers relative to controls from 0 to 50 d (P less than .05). After withdrawal these measurements increased no further in the treated steers. Marbling scores were decreased (P less than .05) in clenbuterol-fed steers after 50 d of treatment; this effect persisted after 128 d of withdrawal from treatment. Shear force values were increased 19% (P less than .05) by feeding clenbuterol for 50 d and remained greater (P less than .05) in treated animals after 128 d. Subcutaneous adipocytes in clenbuterol-fed steers were smaller (P less than .05) than those of controls after 50 d, and this effect was still apparent after the 78-d withdrawal period. Rates of lipogenesis did not differ (P less than .05) between treated and control animals at any time. Perirenal (p.r.) adipocytes were smaller (P less than .05) in treated animals after 50 d, but this effect disappeared by the end of the experiment. There was no indication of a bimodal distribution of smaller s.c. or p.r. adipocytes in either of the treatment groups. Apparent hyperplasia of s.c. adipocytes occurred in the area of the 9-10-11th rib in both treated (P less than .10) and control animals (P less than .05) from 0 to 50 d on trial. Within treated animals there was a significant increase (P less than .05) in total adipocytes in this depot during the withdrawal period. Although the effects of clenbuterol on muscle growth generally were reversed after 78 d, the effects of the beta-adrenergic agonist on adipose tissue development were more permanent.