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Biomedical subjects

James A Shaw

Publications and source records attributed to James A Shaw.

14 recordsLinked to original sources
PubMed2005

Effect of stent implantation on upstream coronary artery compliance--a cause of late plaque rupture?

Stent implantation in the rabbit aorta has been shown to increase vessel wall compliance at the inflow to the stent, but it is uncertain whether similar effects might be seen in the coronary arteries of humans and whether this would have any significant clinical consequences. First, we measured vessel compliance (systolic lumen area--diastolic lumen area/pulse pressure) before, immediately after, and at the 6-month follow-up visit at a site 5 mm upstream of the proximal edge of an implanted coronary stent in patients undergoing coronary intervention using motorized pull-back intravascular ultrasound recordings. Compliance in the upstream segment increased significantly immediately after stenting (before 7.13 +/- 1.49 vs after 10.73 +/- 1.36 mm2/mm Hg, p = 0.03), an effect that was unchanged at 6 months of follow-up (11.84 +/- 2.11 mm2/mm Hg, p = 0.08 vs before stenting). Second, we examined the site of plaque rupture in all patients presenting with an acute coronary syndrome in whom the culprit lesion was in a vessel that had had a stent implanted >12 months previously (n = 31). Plaque rupture was statistically more likely at the inflow to the stent (n = 22) than at other sites within the culprit vessel (n = 9, p <0.01). We conclude that stenting causes an increase in vessel compliance immediately proximal to the stent, and that when a vessel has been previously stented, plaque rupture is most likely to occur at the stent inflow site.

Aged↗
PubMed2005

Approaches to difficult filter retrieval in carotid stenting.

The treatment of carotid disease continues to evolve with an increasing number of the lesions being successfully treated percutaneously. A large part of the success of percutaneous therapy has resulted from the use of distal protection devices and their ability to reduce embolization and subsequent strokes. However, device retrieval through implanted stents can be problematic. We describe situations in which difficulty was encountered advancing the distal protection filter retrieval device through the stent, as well as the different approaches to solve this potential problem.

Aged↗
PubMed2005

Nonmalignant superior vena cava syndrome: pathophysiology and management.

Superior vena cava (SVC) syndrome occurs following obstruction either from external compression or internal thrombosis or scarring. In the past, treatment was limited to medical therapy or surgical bypass but now percutaneous revascularization presents a viable therapeutic option. We present our experience in the percutaneous therapy of patients with nonmalignant SVC syndrome and review the condition with regard to its pathophysiology and management.

Blood Vessel Prosthesis Implantation↗
PubMed2004

Use of suture-mediated vascular closure devices for the management of femoral vein access after transcatheter procedures.

Groin complications remain the most common complication of cardiac catheterization procedures. While the use of closure devices is increasing for arterial sheaths, venous sheaths tend to be removed and hemostasis achieved with manual compression. We report our experience using Perclose suture-mediated vascular closure device to achieve hemostasis and early mobility in patients who have had venous access as part of their procedure. There were a total of 42 patients (21 males; average age, 63.5 years) studied. The majority of the patients had 7 Fr sheaths (24), with access sites of sheaths up to 14 Fr being closed with this technique. Two patients developed complications at the access site: one patient requiring rehospitalization for intravenous antibiotics because of late access site infection, and one patient with deep venous thrombosis and pulmonary emboli. We conclude that the use of the Perclose suture-mediated closure device for closure of femoral venous access sites is feasible and should be considered especially in patients with larger venous sheaths and those at increased risk of groin complications.

Cardiac Catheterization↗
PubMed2004

Recurrent varus angulation after high tibial osteotomy: an anatomic analysis.

Recurrent varus deformity and an associated lateral instability are a common and perplexing concern after high tibial osteotomy. An anatomic study using fresh cadaver specimens was done to delineate the cause of this complication. A closing wedge osteotomy was done on four cadaveric knees, which then were subjected to a small varus load to simulate the adduction moment experienced by the knee during normal gait. The osteotomy was progressively closed in 5 degree increments and the angular alignment of the knee was measured with each incremental change. Experimental results identified postosteotomy angular corrections to be 50%, or less, of the predicted value. As the osteotomy was closed progressively the lateral joint space increased concomitantly, creating an effective lateral instability and negating much of the angular correction afforded by the osteotomy. At osteotomy angles greater than 10 degrees the lateral collateral ligament was rendered nonfunctional with the lateral capsule and the anterior cruciate ligament assuming the primary function of stabilizing the lateral side of the knee. As commonly done, a closing wedge valgus tibial osteotomy does not alter the lateral collateral tension, which allows the knee to swing back toward native alignment when subjected to a varus load.

Humans↗
PubMed2003

An unusual cause of claudication.

We describe a case of a patient who presented with claudication 3 months following a coronary angiogram in which the femoral arterial puncture site had been closed with an AngioSeal. The lesion was found to be due to the anchor of the AngioSeal, which embolized during attempted percutaneous revascularization and had to be snared and retrieved to the level of the sheath in the left femoral artery and was then surgically removed.

Cardiac Catheterization↗
PubMed2003

Carotid stenting in the bovine arch.

We report our experience in stent-supported angioplasty of the left internal carotid artery in patients with anomalous origin of the left common carotid, the so-called bovine arch, in which the right brachiocephalic and left carotid share a common trunk from the aortic arch. The occurrence of the anatomic variant is discussed, and techniques of femoral, brachial, and radial approaches are described.

Aged↗
PubMed2003

Patellar retinacular peel: an alternative to lateral retinacular release in total knee arthroplasty.

The need to perform a lateral retinacular release (LRR) during total knee arthroplasty (TKA) may be lessened or eliminated by performing a patellar retinacular peel (PRP). PRP involves peeling the extensor retinaculum off the dorsolateral border of the patella to the extent necessary to facilitate patellar eversion. Generally, a portion of the lateral patellar facet is removed to allow conformity with a round patellar prosthesis. The combination of retinacular peel and partial facetectomy decreases lateral retinacular tension, which reduces the tendency toward lateral subluxation. In the study reported here, a series of 50 TKAs that included a PRP in all cases was compared with an earlier series of 50 TKAs that included LRR for control of patellar tracking, as needed. The incidence of anterior knee pain was lower in the PRP group than in the LRR group, though this difference was not significant from a statistical perspective. The 2 groups were virtually identical on other comparison criteria. PRP seems to be a viable alternative to LRR.

Aged↗
PubMed2002

Determinants of coronary artery compliance in subjects with and without angiographic coronary artery disease.

OBJECTIVES: The goal of this study was to determine factors contributing to the biomechanical properties of coronary arteries in people with and without angiographic coronary artery disease (CAD). BACKGROUND: The stiffness of the aorta is known to increase with increasing age and in the presence of CAD. However, little is known about the mechanics of coronary arteries, which may have important clinical consequences. METHODS: Intravascular ultrasound was used to determine the mechanical properties of coronary arteries and plaque behavior in subjects with CAD (n = 38), those with chest pain but angiographically normal coronary arteries (N) (n = 9) and those early (<2 weeks) after cardiac transplant (T) (n = 14). RESULTS: Coronary arteries dilated during systole in all groups, but cross-sectional compliance and distensibility were lowest in the proximal left anterior descending artery (LAD) in the subjects with CAD compared with the N and T groups (compliance: 1.2 +/- 0.2 vs. 1.7 +/- 0.5 and 2.7 +/- 0.6 x 10(-2) mm(2) mm Hg(-1) [mean +/- SEM] respectively, p < 0.02 CAD vs. T; distensibility: 0.8 +/- 0.2 vs. 1.7 +/- 0.5 and 1.7 +/- 0.3 x 10(-3) mm Hg(-1), p < 0.05 CAD vs. T). There was extensive plaque in the CAD group, and plaque was also present in the N group, but minimal atheroma was present in the T group. Plaque cross-sectional area diminished significantly during systole in both the LAD and circumflex arteries. Absolute changes were: 0.50 +/- 0.30, 0.33 +/- 0.11 and 0.68 +/- 0.13 mm(2) in the proximal LAD, distal LAD and proximal circumflex arteries, respectively. In subjects with atheroma, there was a significant correlation between cross-sectional compliance and plaque compression at all sites, and plaque compression was a significant determinant of cross-sectional compliance at both proximal sites in multiple regression analyses with age, mean arterial pressure and extent of plaque as the other independent variables. CONCLUSIONS: A major determinant of the systolic increase in coronary luminal area in patients with atheroma is a reduction in plaque cross-sectional area during systole.

Adult↗