PubMed Health⌕ Search

Biomedical subjects

J W Shaw

Publications and source records attributed to J W Shaw.

41 records · Page 3Linked to original sources
PubMedDate not supplied

Aortic bifurcation reconstruction: use of the Memotherm self-expanding nitinol stent for stenoses and occlusions.

PURPOSE: To assess the technical success, initial clinical outcome, and intermediate follow-up of the Memotherm nitinol self-expanding stent in aortic bifurcation reconstruction. METHODS: Thirty-three patients (13 male, 20 female), mean age 64 years, were treated, who had symptoms classified by the Surgical Vascular Society/International Society of Cardiovascular Surgery (SVS/ICVS) classification as grade 2 in 11 (33%), grade 3 in 19 (58%) and grade 4 in 3 (9%) patients. Lesions were classified according to severity and type. Indications for placement of a Memotherm nitinol self-expanding stent were failed angioplasty in 14 (42%), chronic occlusions in 12 (37%), and complex stenoses in seven (21%) patients. RESULTS: Sixty-seven stents were technically successfully placed in 66 aorto-iliac segments in 33 patients, with one major complication. Initial clinical outcome was improvement in 25 (81%), no change in four (13%), and a worsening in two (6%) patients by Rutherford criteria. Mean early ankle/brachial pressure index (ABI) gain was 0. 27 for occlusions and 0.05 for stenoses. Clinical follow-up was obtained in all patients, with retrospective angiographic follow-up in 28 (85%) at a mean of 16 months (range 12-26 months). The decrease in ABI and the decrease in angiographic luminal diameter at follow-up was determined as the "late loss." The mean ABI late losses were -0.06, 0.00, and 0.09, and the mean angiographic late losses were 6.7%, 10% and 14% for occlusions, stenoses, and normal segments respectively. Primary clinical patency was 96%, primary angiographic patency was 89%, and secondary angiographic patency was 93%. CONCLUSION: The high technical success of stent placement, the low complication rates for aortic bifurcation reconstruction using the Memotherm self-expanding stent, and high clinical and angiographic patency maintained at intermediate follow-up support their use in aortic bifurcation reconstruction.

Adult↗
PubMedDate not supplied

The action of histamine on pulmonary vessels of cats and rats.

1. The actions of histamine on pulmonary vascular smooth muscle have been studied in isolated cat and rat lungs perfused with blood, lobes of cat lung perfused in vivo and isolated strips of rat, cat and rabbit pulmonary artery. 2. In all the lung preparations histamine caused both dilatation and constriction. In the rat strips it caused both contraction and relaxation. Dilatation was only well shown when the vessels were in a prior constricted state. In any one lung dilatation occurred with smaller doses than constriction. 3. Histamine caused both increases and decreases in pulmonary artery pressure in collapsed lungs. In this condition these effects are unlikely to have been a consequence of changes in airway pressure. 4. From forward and reverse perfusions of lungs in the waterfall state, where changes in postalveolar vessels do not affect pulmonary artery pressure, it appeared that histamine caused both dilatation and constriction on both sides of the point of collapse caused by alveolar pressure. 5. Plots of the relationship between left atrial and pulmonary artery pressure (at constant alveolar pressure and blood flow) showed that histamine caused both increases and decreases in pulmonary vascular resistance and sometimes also increased the "Starling resistor" properties of lung vessels. 6. In plethysmograph experiments histamine caused moderate dilatation and constriction without affecting lung volume but strong vasoconstriction was accompanied by increases in lung volume.

Animals↗
PubMedDate not supplied

Increased activity of oxygen free radicals during reperfusion in patients with peripheral arterial disease undergoing percutaneous peripheral artery balloon angioplasty.

Modern balloon angioplasty plays an important role in the treatment of localized arterial lesions in patients with peripheral vascular disease (PVD). However, the process of angioplasty produces a situation of acute ischaemia followed by reperfusion and animal studies have shown such situation to be associated with an increase in free radical (FR) generation. FRs cause tissue damage and may be prothrombotic and may therefore contribute to the occurrence of restenosis. Release of FRs during reperfusion has not been fully investigated in humans. We studied the FR activity in 44 patients with PVD in the superficial or popliteal arteries receiving angioplasty treatment. Thirty patients had stenotic lesions and 14 had totally occlusive disease. Baseline blood samples were taken from the arterial catheter for the assay of malondialdehyde (MDA) (spectrophotometric thiobarbituric acid assay) immediately before and after balloon inflation. MDA is a measure of lipid peroxidation which is an indicator of FR activity. MDA levels during reperfusion were significantly higher than those immediately prior to balloon inflation [8.4 (0.29) vs 8.1 (0.24) mumol/l, respectively; mean increase--0.34 (0.13) mumol/l; [mean (sem)] p less than 0.01 (paired Wilcoxon rank test)] in the stenotic lesions. Such changes were not observed in the totally occlusive lesions [7.26 (0.39) vs 7.26 (0.48) mumol/l, respectively; p = 0.75]. Our study has shown increased FR release following angioplasty in patients with stenotic, but not occlusive, peripheral vascular lesions. Angioplasty of the stenotic lesions creates++ a situation of acute ischaemia and reperfusion whereas that of the occlusive lesions leads to the reperfusion of a chronically ischaemic area.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗