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Biomedical subjects

M K O'Malley

Publications and source records attributed to M K O'Malley.

At least 19 recordsLinked to original sources
PubMed2004

Carotid artery angioplasty for restenosis following endarterectomy.

INTRODUCTION: The higher complication rate associated with the surgical treatment of restenosis following carotid endarterectomy (CEA) has led several authors to advocate angioplasty as the treatment of choice in the management of restenosis. We describe our experience with internal carotid artery angioplasty for post-endarterectomy restenosis over 7 years. PATIENTS AND METHODS: From January 1994 to April 2001, all patients with a >90% restenosis following CEA were considered for angioplasty. Thirty angioplasties were carried out in 25 patients, 80% (24/30), for asymptomatic recurrent stenosis. There was no difference between those who had intervention for recurrent stenosis (n=31) and those who did not (n=545) in age, sex, smoking status or incidence of diabetes or hypertension. A significantly greater number of patients who underwent angioplasty were hypercholesterolaemic (p<0.05, Chi-squared test). RESULTS: Mean time from surgery to angioplasty was 13 months (range 1-23). Angioplasty was technically successful in 29 cases (97%). Three patients (10%) experienced transient neurological symptoms during the procedure. There were no strokes. Ninety-six percent (28/29) of patients were followed up with duplex scanning. Mean follow-up was 20 months (range 2-48). Three patients developed a greater than 90% restenosis. CONCLUSION: Angioplasty is an acceptable alternative to surgery in the management of internal carotid artery restenosis following endarterectomy.

Aged↗
PubMed1995

Microvascular disease and anastomotic dehiscence in the colon.

Platelet-derived serotonin released in response to tissue manipulation during surgery may contribute to mesenteric arterial vasospasm leading to postoperative anastomotic leakage after colorectal resection. Organ bath experiments were used to demonstrate the efficacy of naftidrofuryl fumarate (NFT) to oppose serotonin-induced vasoconstriction of human mesenteric arteries. Cumulative dose-response curves were derived with and without NFT at 10(-9) and 10(-6) mol/l concentrations. The difference in maximal contractility between the three sets of curves (n = 8 for each) was significant (P < 0.0001). Sensitivity to serotonin in each of the three curves was measured by calculating the concentration for half-maximal response; differences were again significant (P < 0.0001). NFT reduced serotonin-induced contractility in a dose-dependent fashion in rings of human mesenteric arteries in vitro. This suggests a possible role for NFT in reducing mesenteric vasospasm in colorectal surgery.

Anastomosis, Surgical↗
PubMed1994

Value of routine pressure monitoring system changes after 72 hours of continuous use.

OBJECTIVE: To assess the infection potential of not routinely changing invasive monitoring kits and associated plasticware. DESIGN: A prospective, observational study of microbiological contamination of a cohort of pressure monitoring infusion systems. SETTING: Adult intensive care units in a university tertiary care center. PATIENTS: Patients who had invasively monitored arterial, central venous, or pulmonary artery catheters in place for > or = 96 hrs without a change to the system were entered into the study. INTERVENTIONS: Fluid samples were obtained from the proximal stopcock of the monitoring kits every 24 hrs, beginning with a sample at 72 hrs and continuing until either the plasticware or catheter was changed or discontinued. Fluid samples were placed in tryptic soy broth and spread on blood agar plates within 24 hrs. MEASUREMENTS AND MAIN RESULTS: Of 451 intervals in which the system remained unviolated for > or = 96 hrs except for sampling, no positive cultures were found. Of the 333 monitoring kits/lines in the study, four cultures became positive within 48 hrs of a violation of the system (flush bag change). Positive cultures were obtained from two different patients, one patient having positive fluid cultures from arterial, central venous, and pulmonary arterial kits. This bacterial growth would not have been eliminated with routine system changes as it occurred within a 48-hr timeframe. CONCLUSIONS: Invasive hemodynamic pressure monitoring systems including tubing and plasticware need not be changed routinely as these changes may cause a higher incidence of contamination due to increased violations of the systems.

Adult↗
PubMed1993

High prevalence of unsuspected abdominal aortic aneurysm in patients with confirmed symptomatic peripheral or cerebral arterial disease.

A group of 561 consecutive patients with proven symptomatic peripheral or cerebral arterial disease attending a vascular clinic was screened for abdominal aortic aneurysm (AAA) using B-mode ultrasonography. An aneurysm was present in 40 of 358 men (11.2 per cent) and 13 of 203 women (6.4 per cent), a total prevalence of 9.4 per cent. Thirty-three aneurysms were 3-4 cm in diameter. The prevalence of AAA was similar in patients referred with lower-limb and with cerebral ischaemia. Physical examination for AAA was performed in 200 patients before ultrasonography. The sensitivity of physical examination in the detection of aneurysm was 43 per cent (57 per cent for AAA > or = 4 cm in diameter, 29 per cent for AAA < 4 cm in diameter). Physical examination was an inadequate method of screening. Initial follow-up showed a mean aneurysm expansion rate of 0.20 cm/year. Patients with arterial disease have a high risk of AAA; routine ultrasonographic screening should be considered.

Aortic Aneurysm, Abdominal↗
PubMed1992

Colour-coded duplex ultrasonography in the selection of patients for endovascular surgery.

Endovascular surgery using angioplasty or atherectomy may potentially relieve the symptoms of claudicants with minimal morbidity, but results are best when short stenoses are treated. In this study, colour-coded duplex ultrasonography has been compared with angiography. In aortoiliac segments duplex examination had a sensitivity of 88 per cent and a specificity of 100 per cent; in femoropopliteal disease the sensitivity was 100 per cent and duplex scanning identified more disease than angiography. Subsequently, 73 symptomatic limbs with femoropopliteal disease were scanned to assess their suitability for endovascular surgery. Of these limbs, 27 (37 per cent) had suitable lesions and the remaining 46 (63 per cent) were spared angiography. Colour-coded duplex ultrasonography can reliably be used to select patients for endovascular surgery.

Aorta, Abdominal↗
PubMed1992

Serotonin-induced contractility in human saphenous vein is inhibited by naftidrofuryl.

Vascular endothelial denudation contributes to vasospasm by causing platelet aggregation and the subsequent release of vasoconstrictors such as serotonin. It has recently been suggested that naftidrofuryl fumarate (NFT) may oppose serotonin-induced vasoconstriction. Fourteen rings of human saphenous vein from 14 patients undergoing varicose vein surgery were tested in standard organ bath experiments. Cumulative dose-response curves and maximal contraction in response to serotonin were recorded and this was repeated in the presence of NFT at 10(-6) and 10(-3) mol/l. The difference in maximal contractility between the three sets of curves was significant (P < 0.0001). Sensitivity to serotonin in each of the three curves was measured using the concentration for half-maximal response; differences were again significant (P < 0.0001). It is concluded that NFT reduces serotonin-induced contractility in a dose-dependent fashion in rings of human saphenous vein in vitro. These results suggest a possible role for NFT in reducing vasospasm and support further investigation of this drug.

Dose-Response Relationship, Drug↗
PubMed1992

Long-term reduction of intimal hyperplasia by the selective alpha-1 adrenergic antagonist doxazosin.

Studies have shown that alpha 1-adrenergic blockade reduces intimal hyperplasia in the rabbit aorta. In this study a selective alpha 1-adrenergic antagonist, doxazosin, has been used to examine whether this effect is persistent and dose dependent. Forty-eight New Zealand White rabbits underwent endothelial denudation of the abdominal aorta using a Fogarty balloon catheter. Test rabbits were given low-dose (2 mg) or high-dose (8 mg) doxazosin daily and all animals killed at either 1 or 12 weeks after the procedure. The aortas were harvested after fixation in situ with 4 per cent glutaraldehyde and neointimal hyperplasia was measured, using an x-y digitizer, as the percentage reduction in luminal cross-sectional area. At 1 week after surgery, rabbits receiving the low dose had a median area reduction of 7.7 per cent and those receiving the high dose a reduction of 8.2 per cent; both had significantly less intimal hyperplasia than control rabbits, which had a median area reduction of 14.8 per cent (P < 0.01). However, at 12 weeks, when compared with the 32.6 per cent reduction in the control group, only those rabbits receiving high-dose doxazosin had significantly less intimal hyperplasia, with a reduction of 5.5 per cent (P < 0.001). It is concluded that selective alpha 1-adrenergic blockade significantly reduces neointimal hyperplasia, that this effect is dose dependent, and that it persists for at least 3 months.

Animals↗
PubMed1992

The reproducibility of colour-coded duplex scanning in measuring arterial wall dimensions.

Intimal hyperplasia continues to be a major problem following vascular surgery but experimental evidence suggests that it can be reduced pharmacologically. For clinical studies an accurate, reproducible and non-invasive image of the intima and lumen is required. We have assessed the value of the Acuson 128 Colour Duplex for such studies. Ten patients had their common femoral arteries scanned at a fixed point by two experienced observers on two separate occasions. External vessel diameter, luminal diameter and internal diameter (i.e. the diameter within the internal elastic lamina) were measured in both longitudinal and cross-sectional views. Cross-sectional area and degree of stenosis were all measured and all parameters expressed as limits of agreement. The mean external diameter of the common femoral arteries was 10.5 +/- 1.6 mm. Measurements in the longitudinal view were highly reproducible with limits of agreement ranging from -0.67 - +0.25 mm (internal diameter) to -1.49 - +1.31 mm (luminal diameter). In order to detect a meaningful change in longitudinal external diameter a real difference of 0.86 mm is required representing a change of less than 10%. Cross-sectional diameter measurements were similarly reproducible (-0.73 - +0.47 mm to -1.97 - +1.79 mm). However, cross-sectional area measurements had a wide variation so that the error in degree of stenosis was -25.4 - +30.2%. Thus, duplex ultrasound reproducibly images the layers of the arterial wall. Prospective studies of intimal hyperplasia are feasible but must be based on longitudinal and cross-sectional diameters rather than cross-sectional areas.

Aged↗
PubMed1991

Infrainguinal polytetrafluoroethylene grafts: saved limbs or wasted effort? A report on ten years' experience.

Two-hundred and twenty-four infrainguinal polytetrafluoroethylene reconstructions were performed for critical ischemia over a 10 year period: 48 to the above-knee popliteal artery, 113 to the below-knee popliteal artery, and 63 to the tibial vessels. The cumulative patency rates were 84 +/- 6% and 63 +/- 9% for above-knee popliteal, 53 +/- 5% and 35 +/- 7% for below-knee popliteal, 45 +/- 6% and 30 +/- 9% for tibial vessels at one and five years respectively. Limb salvage rates were 81 +/- 6% and 73 +/- 9% (above-knee popliteal), 69 +/- 5% and 57 +/- 9% (below-knee popliteal), 64 +/- 7% and 32 +/- 10% (tibial vessels) at one and five years respectively. Graft occlusion did not result in limb loss in 32 cases. Preoperatively, 54% of the patients had limited mobility while 43% were regarded as severely restricted. At follow-up, 57% of the patients were considered to be independent, 26% had limited mobility, and 17% were still severely restricted. Polytetrafluoroethylene provides good short-term limb salvage and improved mobility in patients with critical ischemia and poor life expectancy. Its use is well worth the effort.

Activities of Daily Living↗
PubMed1991

Non-specific abdominal pain in pre-menopausal women.

Non-specific abdominal pain (NSAP) is a well-recognized clinical problem which places a significant burden on health resources. We studied 100 premenopausal women who were admitted consecutively through the Accident and Emergency Department of the Mater Misericordiae Hospital to assess final diagnosis, duration of hospital stay, extent of investigation, recurrence of symptoms and final diagnosis. The patients were placed in the following diagnostic categories: Gynaecological (30%), Renal (9%), Acute appendicitis (23%), Miscellaneous (9%) and Non-specific abdominal pain which accounted for 29% of the admissions. The mean duration of hospital stay for patients with NSAP was 67 days, one third underwent specialized investigations and one third underwent appendicectomies for normal appendices. On review, one year after admission, 66% of patients admitted with NSAP were asymptomatic.

Abdominal Pain↗
PubMed1991

Altered catecholamine receptor affinity in rabbit aortic intimal hyperplasia.

Intimal thickening is a universal response to endothelial denudation and is also thought to be a precursor of atherosclerosis. We have demonstrated selective supersensitivity in arterial intimal hyperplasia to norepinephrine and we now report a possible mechanism for this. Binding studies in rabbit aorta with the selective alpha 1-adrenergic radioligand 125I-HEAT demonstrated that there was no change in receptor density (20 +/- 4 fmole/10(6) cells) in intact vascular smooth muscle cells at either 5 or 14 days after denudation. However, competition studies showed a 2.6-fold increase in alpha 1-adrenergic receptor affinity for norepinephrine in intimal hyperplastic tissue (P less than 0.05). This increased affinity for norepinephrine was associated with a greater increase in 32P-labeled phosphatidylinositol (148% intimal thickening versus 76% control) and phosphatidic acid (151% intimal thickening versus 56% control) following norepinephrine stimulation of free floating rings of intimal hyperplastic aorta. These data suggest that the catecholamine supersensitivity in rabbit aortic intimal hyperplasia is receptor mediated and may be linked to the phosphatidylinositol cycle.

Animals↗
PubMed1990

A new technique for bilateral iliac vein and inferior vena cava reconstruction using reinforced polytetrafluoroethylene.

We report on the management of a patient with intractable venous claudication and ulceration due to bilateral iliac vein and inferior vena cava occlusion. An inverted V graft was constructed from two 8 mm diameter reinforced PTFE grafts. The upper end was anastomosed to the inferior infrarenal vena cava and the lower ends anastomosed to the common femoral veins. Bilateral arteriovenous fistulas were fashioned. Nine months later the graft is patent and the patient's only symptom is mild ankle edema. The theoretical advantage of this type of graft is that occlusion of one limb will not compromise the other, thus leaving a number of secondary options open if this should happen.

Aged↗
PubMed1990

"Haemorrhagic" carotid plaque does not contain haemorrhage.

The presence of haemorrhage in carotid bifurcation atheromatous plaques is widely believed to be associated with the production of ischaemic neurological events. This study set out to characterise plaque composition in symptomatic (SYM) and asymptomatic (ASYM) patients and to identify, if possible, the origin of intra-plaque haemorrhage. Fifty-nine plaques (50 SYM and 9 ASYM) were serially sectioned and examined for haemorrhage, haemosiderin, fibrin, cholesterol and collagen. Immunoperoxidase and electron microscopy studies were carried out on sections from five plaques in order to identify blood breakdown products. Intra-plaque haemorrhage was identified in 40 (68%) plaques and was similar in SYM and ASYM plaques. In only one did it constitute more than 15% of plaque content, and in the remainder it consisted of small collections of erythrocytes constituting greater than 1% of plaque content in only 21 (35%) plaques. The predominant non-fibrous component was a pink amorphous material mixed with cholesterol. Apart from traces of platelet breakdown products there was no evidence of haemorrhage in this pink material. Plaque roof rupture or ulceration was seen in 39 (66%) and in almost all cases overlay the amorphous/cholesterol material. Blood vessels were identified in 51 87%) plaques but were in close proximity to haemorrhage in only nine (15%).

Arteriosclerosis↗
PubMed1989

Role for prazosin in reducing the development of rabbit intimal hyperplasia after endothelial denudation.

Intimal hyperplasia is the universal response to endothelial denudation and occurs after a variety of vascular procedures. In a proportion of cases the smooth muscle cell proliferation may lead to stenosis of the blood vessels. These vessels exhibit increased sensitivity to noradrenaline that can be reduced by the alpha 1-adrenergic antagonist prazosin. Because the alpha 1-adrenergic receptor and platelet-derived growth factor (which promotes vascular smooth muscle cell proliferation) act through the same metabolic pathway, it was postulated that alpha 1-adrenergic blockade might reduce the development of intimal hyperplasia. Twenty-eight New Zealand White rabbits underwent endothelial denudation of the aorta using a Fogarty balloon catheter. Test rabbits were treated with prazosin from the day of operation until they were killed. All rabbits were killed either 1 or 4 weeks after endothelial denudation. Intimal hyperplasia in cross-sections of the aorta was measured using an X-Y digitizer and was standardized in terms of percentage luminal reduction. Prazosin-treated rabbits had significantly less luminal reduction at 1 week (0.75(1.8) versus 9.7(3.1) per cent, mean (s.d.), P less than 0.001) and at 4 weeks (14.7(4.4) versus 25.3(12.8) per cent, P less than 0.05) than control rabbits. It is concluded that prazosin caused a major reduction in the development of intimal hyperplasia.

Animals↗