Biomedical subjects

T Hartshorne

Publications and source records attributed to T Hartshorne.

At least 37 records · Page 2Linked to original sources

PubMed1996

Colour-coded duplex imaging can safely replace diagnostic arteriography in patients with lower-limb arterial disease.

The purpose of this study was to review the outcome of adopting colour-coded duplex ultrasonography as the primary imaging modality in patients with symptomatic lower-limb arterial disease. Over a 12-month period 467 consecutive lower-limb duplex scans were performed of which 437 (94 per cent) were technically adequate. Of the 467 limbs, 184 (39 per cent) were managed conservatively, 230 (49 per cent) were referred for percutaneous transluminal angioplasty (PTA), 41 (9 per cent) underwent reconstructive surgery and 12 (3 per cent) required diagnostic arteriography. In patients referred for PTA there were only 22 (10 per cent) unexpected findings; there was agreement about superficial femoral artery occlusion length in 95 (89 per cent) of 107 limbs and about the presence or absence of a superficial femoral artery stump in 91 (85 per cent) of 107 cases. In patients referred for surgery there were no unexpected findings. Colour-coded duplex imaging can safely replace diagnostic arteriography in up to 97 per cent of lower limbs with arterial disease.

Adult↗

PubMed1996

Can lower limb vascular reconstruction be based on colour Duplex imaging alone?

OBJECTIVES: To determine the safety and efficacy of Duplex scanning as the only imaging modality prior to lower limb vascular reconstruction. DESIGN: Retrospective review. SETTING: A single university vascular unit. PATIENTS AND METHODS: Review of all lower limb vascular reconstructions over a 2 year period. RESULTS: Eighty-five limbs underwent vascular reconstruction based on colour Duplex alone. A wide range of revascularising operations were performed, including 29 cases of infragenicular reconstruction. In the latter cases, the findings of Duplex scanning were confirmed by on table pre-reconstruction angiography in 28 cases and the graft occlusion rate in the first month was 14%. There were no postoperative complications that could be attributed to a failure of preoperative Duplex imaging. CONCLUSION: Vascular reconstruction can be undertaken safely in patients with lower limb arterial disease on the basis of Duplex scanning alone.

Adult↗

PubMed1996

A prospective comparison of lower limb colour-coded Duplex scanning with arteriography.

OBJECTIVE: To compare the diagnostic value of colour Duplex scanning with arteriography for the detection of arterial disease of the aortoiliac arteries, femoropopliteal arteries and the origins of the tibial vessels. DESIGN: Prospective, semi-blind study. SETTING: Vascular laboratory and radiology department, University Hospital. METHODS: A total of 1658 arterial segments in 148 limbs were studied both by colour Duplex scanning and digital subtraction arteriography. Individual arterial segments were classified on the basis of peak systolic velocity ratios < 2.0, > or = 2.0 or an absent Doppler signal, as 0-49%, 50-99% diameter reduced, or occluded. The same arterial segments were similarly classified on the basis of arteriography and the two modalities were compared using a Kappa (k) analysis. RESULTS: The overall agreement between arteriography and colour-coded Duplex was kappa = 0.74 (95% CI, 0.70-0.78), this indicates substantial agreement. Kappa values (95% CI) from the aortoiliac, femoropopliteal and the origins of the infrapopliteal arteries were kappa = 0.59 (0.49-0.73; moderate agreement), kappa = 0.80 (0.76-0.84; substantial agreement) and kappa = 0.48 (0.35-0.61; moderate agreement) respectively. CONCLUSIONS: We conclude that there is substantial agreement between colour-coded Duplex and arteriography of the lower limbs, and that the ability of colour-coded Duplex to plan and guide lower limb vascular interventions requires investigation.

Aged↗

PubMed1996

Carotid plaque regression on oestrogen replacement: a pilot study.

OBJECTIVE: To investigate the effect of unopposed oestrogen on atheromatous carotid plaques. SUBJECTS: Seventeen postmenopausal women with known carotid disease. METHODS: Carotid intimal thickness and plaque length and thickness were measured prior to and following 3 and 6 months of treatment, using Duplex ultrasound. A total of 22 plaques were followed up. RESULTS: There was a reduction in plaque length after 3 (-8.14%, p = 0.001) and 6 months (-28%, p = 0.001) of treatment. The reduction in plaque thickness (-18%, p = 0.004) was significant after 6 months of treatment. Reductions in intimal thickness were not statistically significant. CONCLUSION: Our results suggest that oestrogen replacement is associated with significant plaque regression.

Aged↗

PubMed1996

The effect of adjacent segment disease on the accuracy of colour duplex scanning for the diagnosis of lower limb arterial disease.

OBJECTIVE: To assess the effect of multisegment disease upon the accuracy of lower limb colour Duplex scanning. DESIGN: Prospective, semi-blind study. SETTING: Vascular Laboratory and Radiology Department, University Hospital. METHODS: A total of 148 limbs (1106 individual arterial segments) were examined from the distal aorta to the origins of the tibial arteries by colour-coded Duplex and arteriography. Individual segments were graded as 0-49%, 50-99% diameter reduced or occluded on the basis of peak systolic velocity ratios < 2.0, > or = 2.0 or an absent Doppler signal, and compared with similarly graded segments from blinded angiographic studies. The agreement (Kappa analysis) between Duplex and arteriography in segments adjacent to at least one proximal or distal > or = 50% diameter reducing lesion was then compared to the agreement between segments free of adjacent disease. RESULTS: For isolated areas of disease, the kappa value (95% confidence interval) of agreement between Duplex ultrasonography and arteriography was 0.63 (0.53-0.73) and in the presence of neighbouring disease the value was 0.78 (0.73-0.83). CONCLUSION: We conclude therefore that providing appropriate criteria are used, Duplex assessment of lower limb arterial disease is not adversely affected by adjacent disease.

Aged↗

PubMed1996

Unstable carotid plaques: preoperative identification and association with intraoperative embolisation detected by transcranial Doppler.

OBJECTIVES: To investigate whether unstable carotid plaque characteristics, as determined by preoperative colour Duplex ultrasonography (CDU) and postoperative histological examination, were associated with particulate embolisation, detected by transcranial Doppler (TCD), during the initial dissection of the carotid bifurcation during carotid endarterectomy(CEA). DESIGN: A prospective, consecutive study was undertaken of 50 patients undergoing carotid endarterectomy(CEA). SETTING: Leicester Royal Infirmary, Leicester, U.K. MATERIALS: Carotid plaques were assessed preoperatively using CDU. Intraoperative TCD monitoring of the ipsilateral middle cerebral artery was performed using a Scimed 2MHz TCD. Carotid plaques removed at operation were processed histologically and multiple sections assessed microscopically. CHIEF OUTCOME MEASURES: Plaque composition was classified ultrasonically and histologically according to the Gray-Weale classification and plaque surface characteristics were graded according to a five point classification. TCD detected emboli were identified and counted during the initial dissection of the artery. MAIN RESULTS: Particulate embolisation occurred in nine patients. Histologically, embolisation was associated with ulcerated plaque in three cases and ulcerated plaque with associated thrombus in six cases (p = 0.0005). However, the ability of CDU to positively predict embolisation based on the correct identification of an unstable plaque surface was only 25%. CONCLUSIONS: Embolisation during dissection is strongly associated with ulcerated plaque with associated thrombus. CDU is unable to reliably identify these characteristics preoperatively. Intraoperative TCD monitoring can detect potentially harmful embolisation during this stage enabling surgical technique to be modified appropriately.

Arteriosclerosis↗

PubMed1996

Can lower limb ultrasonography replace arteriography?

Although duplex ultrasonography offers a number of theoretical and practical advantages over arteriography for the assessment of lower limb arterial disease, it has not yet been widely accepted into clinical practice. This article reviews the current status of lower limb arterial duplex and concludes that arteriography should no longer be regarded as the diagnostic 'gold-standard' and that duplex ultrasonography should now be the first line investigation in patients with lower limb arterial disease.

Angiography↗

PubMed1995

Percutaneous transluminal angioplasty of infrainguinal vein graft stenosis: long-term outcome.

The aim of this prospective study was to examine the long-term outcome of infrainguinal vein graft stenosis managed by percutaneous transluminal angioplasty (PTA) as first-line treatment. Thirty-three infrainguinal vein graft stenoses detected by graft surveillance during a 44-month period were treated initially by PTA. The median (range) follow-up after angioplasty was 39 (18-56) months. Although 19 stenoses were successfully treated by a single PTA, 14 stenoses recurred at a median (range) interval of 8.5 (1-39) months. Restenosis occurred more frequently in the distal third of a graft (P = 0.002) compared with that in the proximal or mid-grafts, and restenosis was more common in in situ than reversed vein grafts (P = 0.03). It is concluded that infrainguinal vein graft stenoses were successfully treated by single PTA. There was, however, a high restenosis rate after angioplasty of stenosis in the distal third of a vein graft and, while approximately one third of such stenoses can be treated by a single PTA, the optimal management of recurrent stenosis requires further investigation.

Angioplasty, Balloon, Coronary↗

PubMed1995

The long-term outcome of infrainguinal vein graft surveillance.

OBJECTIVES: Vein graft surveillance is of proven benefit in improving graft patency at least in the first year after arterial bypass surgery. The aim of this study was to look at the longer term outcome of a vein graft surveillance programme on graft patency. METHODS: One hundred and twelve consecutive vein grafts in 106 patients were prospectively entered into a vein graft surveillance programme. The median (range) follow up was 34 (1-76) months. RESULTS: There were 23 (21%) early (less than 1 month) failures and a further 15 grafts occluded during follow up. The primary, primary assisted and secondary patencies at 4 years were 27%, 59% and 67% respectively. Thirty-eight grafts (34%) developed at least one stenosis at a median interval of 5 months after the operation. Eight (21%) of these stenoses occurred more than 12 months after surgery and would have been missed had surveillance been curtailed after 1 year. CONCLUSIONS: The benefits of graft surveillance extend beyond one year and surveillance should therefore continue indefinitely.

Adult↗

PubMed1994

A common core structure for U3 small nucleolar RNAs.

U3 nucleolar small RNA (snRNA) is involved in early processing of the primary rRNA transcript. A secondary structure model for the unusually small Trypanosoma brucei U3 snRNA was deduced by chemical modification and enzymatic cleavage of U3 snRNA in deproteinized and ribonucleoprotein (RNP) forms. Comprehensive alignment of U3 snRNAs from vertebrate, plant, fungal and protozoan species clearly delineated conserved and divergent features. The 5' domain of the T. brucei U3 snRNA appears to form one small, flexible 5' stem loop structure followed by a long single-stranded region; this model is a variation on 5' domain structures proposed for other U3 snRNAs which do not conform to a single model. The 3' domain of T. brucei U3 snRNA contains four single-stranded sequences conserved between U3 snRNAs. Of these, structural probing determined that the configurations of GAU region and box B and C sequences are altered by protein interactions in U3 snRNP. Conspicuously, the 3' domains of trypanosomal U3 snRNAs lack stem loops II and III, indicating that these structures are not required for conserved U3 snRNA functions.

Animals↗

PubMed1994

Treatment and outcome of severe lower-limb ischaemia.

The overall outcome of severe lower-limb ischaemia in terms of limb salvage and mortality is poorly documented. A consecutive series of 232 severely ischaemic legs in 209 patients was therefore studied. An aggressive policy of revascularization has been pursued; this was attempted in 89 per cent of legs, with a primary amputation rate of 8 per cent. The perioperative 30-day limb salvage rate was 79 per cent with a patient mortality rate of 20 per cent. At 12 and 24 months the limb salvage rates were 74 and 71 per cent and patient survival rates 75 and 73 per cent respectively. To identify high-risk groups the effects on limb salvage and mortality of age, sex, presentation, diabetes and ankle systolic pressure of 50 mmHg or less were studied. Using life-table analysis, none of the preoperative risk factors had an effect on limb salvage and mortality. An aggressive policy of revascularization provides excellent results in the treatment of patients with severe leg ischaemia.

Adult↗

PubMed1994

Characterization of putative small nuclear RNAs from Giardia lamblia.

Small nuclear RNAs (snRNAs), which have roles in RNA metabolism, have been found in all eukaryotic cells. Candidate snRNAs were identified in the primitive protozoan parasite, Giardia lamblia, by either immunoprecipitation of total RNA with antiserum directed against the 2,2,7-trimethylguanosine cap structure characteristic of snRNAs or by Northern hybridization with oligonucleotide probes complementary to snRNA consensus sequences. Isolated putative snRNAs include eight 2,2,7-trimethylguanosine-capped species: RNAs A through H, and one non-2,2,7-trimethylguanosine-capped species: RNA J. Single copy genes encoding RNA D, RNA H and RNA J were cloned and sequenced, and the 5' end of each RNA was determined by primer extension analysis. Certain characteristics suggest tentative identification of these Giardia RNAs as nucleolar RNAs with possible roles in rRNA processing.

Animals↗

PubMed1994

Subintimal angioplasty of femoropopliteal artery occlusions: the long-term results.

The technique of subintimal angioplasty has been attempted on 200 consecutive femoropopliteal artery occlusions of median (range) length 11 (2-37) cm. The principle of the technique is to traverse the occlusion in the subintimal plane and recanalise by inflating the angioplasty balloon within the subintimal space. The technical success rate was 159/200 (80%) and was not significantly different for occlusions < 10 cm (81%, n = 73), 11-20 cm (83%, n = 63) or > 20 cm (68%, n = 23), p = 0.20. There were no deaths nor limb loss resulting from the procedure. The median (range) ankle-brachial pressure index increased from 0.61 (0.21-1.0) preangioplasty to 0.90 (0.26-1.50) postangioplasty. The actuarial haemodynamic patencies of technically successful procedures at 12 and 36 months were 71% and 58% respectively, the symptomatic patencies were 73% and 61%. A multiple regression analysis showed that smoking multiplied the risk of reocclusion by 2.70 (p < 0.001), each additional run-off vessel reduced the risk by 0.54 (p < 0.001) and the risk increased by 1.73 (p = 0.020) for every 10 cm of occlusion length. In conclusion, the technical success rate (80%) of subintimal angioplasty for femoropopliteal occlusions is unrelated to occlusion length and for all procedures, including technical failures, cumulative symptomatic and haemodynamic patencies of 46 and 48% can be achieved at 3 years. The factors influencing long-term patency were smoking, the number of calf run-off vessels and occlusion length.

Aged↗

PubMed1993

Interventional radiology in the maintenance of infrainguinal vein graft patency.

The impact of interventional radiology on the cumulative patency rate of 112 consecutive infrainguinal vein grafts was reviewed. The primary, primary assisted and secondary cumulative patency rates at 42 months were 40, 65 and 69 per cent respectively. The difference between primary and primary assisted patency rates (40 versus 65 per cent, P = 0.001) resulted from the early detection and treatment of stenoses in 30 grafts by percutaneous transluminal angioplasty (PTA). Interventional radiology also improved the cumulative graft patency rate through PTA of one inflow and five outflow arteries, thrombolysis of two graft occlusions, embolization of two persistent arteriovenous fistulas and salvage of one graft on the first day after operation by percutaneous aspiration of distal graft thrombus. Interventional radiology has a crucial role to play in the maintenance of infrainguinal vein graft patency; provided that graft stenoses are detected early in their development by aggressive graft surveillance, PTA is a highly effective treatment.

Adult↗

PubMed1993

The role of pulse-generated run-off, Doppler ultrasound and conventional arteriography in the assessment of patients prior to femorocrural bypass grafting.

One of the most important prerequisites prior to femorocrural bypass is the identification of a patent calf vessel. To determine the ability of three preoperative investigations to demonstrate patent distal vessels we compared preoperative conventional arteriography, Doppler ultrasound measurement of ankle systolic pressure (ASP) and pulse generated run-off (PGR). PGR and ASP both identified significantly more calf vessels than did preoperative conventional arteriography. However, only PGR had the ability to distinguish those vessels suitable for bypass grafting from those unsuitable for grafting. These results demonstrate that PGR is the investigation of choice prior to femorocrural bypass.

Aged↗

PubMed1993

RNA B is the major nucleolar trimethylguanosine-capped small nuclear RNA associated with fibrillarin and pre-rRNAs in Trypanosoma brucei.

RNA B is one of three abundant trimethylguanosine-capped U small nuclear RNAs (snRNAs) of Trypanosoma brucei which is not strongly identified with other U snRNAs by sequence homology. We show here that RNA B is a highly diverged U3 snRNA homolog likely involved in pre-rRNA processing. Sequence identity between RNA B and U3 snRNAs is limited; only two of four boxes of homology conserved between U3 snRNAs are obvious in RNA B. These are the box A homology, specific for U3 snRNAs, and the box C homology, common to nucleolar snRNAs and required for association with the nucleolar protein, fibrillarin. A 35-kDa T. brucei fibrillarin homolog was identified by using an anti-Physarum fibrillarin monoclonal antibody. RNA B and fibrillarin were localized in nucleolar fractions of the nucleus which contained pre-rRNAs and did not contain nucleoplasmic snRNAs. Fibrillarin and RNA B were precipitated by scleroderma patient serum S4, which reacts with fibrillarins from diverse organisms; RNA B was the only trimethylguanosine-capped RNA precipitated. Furthermore, RNA B sedimented with pre-rRNAs in nondenaturing sucrose gradients, similarly to U3 and other nucleolar snRNAs, suggesting that RNA B is hydrogen bonded to rRNA intermediates and might be involved in their processing.

Animals↗

PubMed1993

Early results of combined carotid endarterectomy and coronary artery bypass grafting in patients with severe coronary and carotid artery disease.

The management of patients with carotid artery disease who require coronary artery bypass grafting (CABG) remains controversial. Several published series from the USA (including one with prospective randomization) advocate a combined approach of carotid endarterectomy (CEA) followed immediately by coronary artery bypass surgery. However, experience of combined carotid endarterectomy and coronary bypass grafting has not been previously reported by a centre from the United Kingdom. Between 1986 and 1991 we performed this combined procedure on 18 patients who required myocardial revascularization and had co-existing severe (> 70%) carotid stenosis. Sixteen patients (89%) had angina and 11 patients (61%) had symptomatic carotid artery disease. The perioperative mortality was 5.5% and the ipsilateral perioperative stroke rate was 5.5%. These early results are encouraging and suggest that further evaluation of combined carotid endarterectomy and coronary artery bypass surgery is warranted.

Adult↗

PubMed1992

Transcutaneous ultrasound measurement of blood-flow in internal mammary artery to coronary artery grafts.

Transcutaneous doppler ultrasound was used to examine internal-mammary-artery (IMA) blood-flow in 26 patients with IMA coronary bypass grafts. The ungrafted right IMA could be seen in all of 19 patients, the grafted left IMA in 16 of 26, and the grafted right IMA in 3 of 7. The velocity profile recorded from the proximal part of the grafted IMA is distinct from that of an ungrafted artery, with a systolic peak which reflects graft capacitance in the face of high intramyocardial resistance, and a diastolic peak which represents graft conductance when intramyocardial resistance is low. Total graft blood-flow can be estimated from the mean velocity and the measured vessel diameter; resting flows ranged from 22 to 79 ml/min. In recently grafted patients, resting graft blood-flow correlated with myocardial "run-off" estimated from preoperative arteriograms; graft blood-flow increased appropriately with exercise. This simple, non-invasive technique to measure IMA graft blood-flow may find applications for routine postoperative follow-up of patients with IMA grafts and for studies on the physiology and pharmacology of coronary artery blood-flow.

Blood Flow Velocity↗