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Biomedical subjects

M H Simms

Publications and source records attributed to M H Simms.

At least 37 records · Page 2Linked to original sources
PubMed1992

Claudication induces systemic capillary endothelial swelling.

An in vivo model of intermittent claudication has been developed to investigate systemic reperfusion injury associated with transient muscle ischaemia. Rats were subjected to unilateral common iliac artery ligation and two weeks of intermittent hind limb muscle stimulation. Electron microscopy demonstrated a significantly increased percentage of swollen capillary endothelial cells both locally and systemically in these "claudicant" rats, compared with controls or those undergoing muscle stimulation or artery ligation alone. These results support human data suggesting that claudication induces an inflammatory response which results in systemic vascular injury.

Animals↗
PubMed1992

Ruptured mycotic aneurysm of the abdominal aorta in childhood.

Aortic aneurysms are exceedingly rare in childhood and, when mycotic, the risk of rupture is high. We report a case of ruptured mycotic abdominal aortic aneurysm presenting in a 9 year old girl, that was successfully repaired after initial misdiagnosis.

Aneurysm, Infected↗
PubMed1992

Peripheral pulse palpation: an unreliable physical sign.

Fifty observers, including two fully trained vascular surgeons, were asked to determine the presence or absence of the femoral and distal pulses of four patients with peripheral vascular disease and one asymptomatic subject (50 pulses assessed). Pulses felt by both vascular surgeons were deemed to be palpable. Among the other observers, the sensitivity of palpation was 95% or over for the femoral pulse, but 33% to 60% for observers of varying experience feeling for the posterior tibial pulse. Up to 20% false-positive observations were reported. Disease was diagnosed in over 10% of examinations of healthy limbs and was missed in over 10% of symptomatic limbs. The accuracy of pulse palpation was strongly correlated with the systolic blood pressure in the underlying artery. Accuracy was greater among more experienced observers, suggesting that careful teaching of this skill is likely to be beneficial. Even so, pulse palpation alone is an unreliable physical sign and should only be used in combination with objective measurements as a guide to clinical management.

Blood Pressure↗
PubMed1991

Aggressive arterial reconstruction for critical lower limb ischaemia.

A consecutive series of 315 patients underwent arterial reconstruction for 329 critically ischaemic lower limbs over a 5-year period. Patients were not excluded from limb salvage surgery on the basis of poor run-off on preoperative angiography. Femorocrural bypass to a single calf vessel was required in 239 limbs (73 per cent); the 30-day cumulative mortality rate was 7 per cent, rising to 41 per cent at 5 years. Cumulative graft patency at 30 days, 1 year, 2 years and 5 years was 96, 85, 84 and 82 per cent respectively and was independent of the level of reconstruction. In situ long saphenous vein was the conduit of choice for distal bypass but, when this was absent, satisfactory results were obtained with arm vein or composite vein grafts. Acceptable results can be obtained for reconstructive surgery without preoperative angiographic selection of patients. An aggressive approach to limb salvage is therefore justified.

Aged↗
PubMed1991

Failed femorocrural reconstruction does not prejudice amputation level.

From January 1985 to December 1989, 500 consecutive patients presented to a single vascular unit with limb-threatening acute or critical ischaemia. Vascular reconstruction was attempted unless the patient had insufficient viable tissue to permit weight bearing or complete absence of run-off vessels in the calf. Fifty patients underwent a primary amputation and 450 patients underwent vascular reconstruction, of whom 265 had a femorocrural bypass. Sixty secondary amputations were performed following femorocrural bypass failure. The below-knee amputation to above-knee amputation ratio (BKA:AKA) was 2.0 in the primary amputation group and 1.1 in the secondary amputation group. Direct comparison between the two groups is not valid as they are clinically different. The combined BKA:AKA ratio was 1.4. This compares favourably with the BKA:AKA ratio of recent published series and figures from the National Amputation and Limb Fitting Services. It suggests that an unselective policy of vascular reconstruction for critical ischaemia does not lead to a higher proportion of above-knee amputations.

Acute Disease↗
PubMed1991

Iloprost improves femoro-distal graft flow after a single bolus injection.

A double-blind, randomised, placebo-controlled trial was conducted to study the effect of the stable prostacyclin analogue iloprost on femoro-distal graft blood flow. After completing femoro-distal reconstruction, 3000 ng of iloprost or placebo was injected into the graft over 2 min. Graft blood flow, measured by electromagnetic flowmetry, increased by a mean (range) of 94% (12 to 192%) in patients receiving iloprost (n = 15) compared to 6% (-34 to 53%) in controls (n = 16; p less than 0.0001, t-test). Increased graft flow, measured by duplex ultrasound, was maintained in the iloprost group over a 7 day period postoperatively (F = 5.2, p = 0.03; analysis of variance) and remained higher at 7 days (p = 0.007, t-test). Iloprost produces an immediate, sustained increase in graft blood flow after femoro-distal reconstruction and may therefore be of benefit in reducing the incidence of early graft failure.

Aged↗
PubMed1990

Effect of surgery on the systemic inflammatory response to intermittent claudication.

The hypothesis that intermittent claudication initiates a systemic inflammatory response was investigated by studying the effect of exercise on markers of neutrophil activation and vascular permeability in 25 claudicants and 10 controls. Urinary albumin excretion, previously demonstrated to reflect vascular permeability, increased significantly after exercise in claudicants and was associated with decreased neutrophil filterability and increased serum lysozyme activity. No similar exercise-induced changes were seen in controls or in claudicants after successful arterial bypass surgery. These results suggest that intermittent claudication is associated with potentially deleterious systemic manifestations that are surgically reversible.

Aged↗
PubMed1990

Femoro-distal graft flow augmentation with the prostacyclin analogue iloprost.

The possible application of the prostacyclin analogue Iloprost to improve the results of arterial surgery has been studied. On completion of femoro-distal reconstruction, intra-graft administration of Iloprost caused an increase in graft blood flow measured by electromagnetic flowmetry. Three thousand nanograms of the drug appeared to be the optimum dose and in 10 patients who received this amount the graft blood flow increased from a mean of 117.6 ml/min to 225.5 ml/min (P less than 0.01, Wilcoxon), a mean (range) increase of 127.9% (54-190) after 20 min. Iloprost requires further evaluation, but may be a useful adjunct to femoro-distal reconstruction.

Aged↗
PubMed1990

Assessment of intermittent claudication by quantitation of exercise-induced microalbuminuria.

Urinary albumin excretion rates, expressed as albumin-creatinine ratios (ACR, mg/mmol) were measured before and after exercise in 23 claudicants and 10 controls. The mean (range) resting ACRs in the claudicants and controls were 4.42 (0.2-34.6) and 0.77 (0.3-2.8) respectively (P less than 0.001). ACR increased after exercise by a mean of 153% in claudicants to 9.7 (0.2-48.1; P less than 0.001) with no change in controls, 0.79 (0.2-2.1). In patients with claudication there was a positive correlation between ankle pressure recovery time and the relative increase in ACR after exercise (r = 0.64, P less than 0.01). The post-exercise increase in ACR was reduced in all nine patients who underwent bypass surgery. Measurement of ACR after exercise appears to be related to severity of muscle ischaemia and may assist in the assessment of patients with intermittent claudication.

Aged↗
PubMed1990

Recurrent aorto-duodenal fistula: a final solution?

This paper describes a case of recurrent aorto-duodenal fistula treated successfully by re-sitting the duodenum in an ante-colic position. Secondary aorto-duodenal fistula affects less than 1% of patients who have received a prosthetic abdominal aortic graft. However following correction of such a fistula the incidence of recurrent fistulation or aortic stump blow-out is reported as high as 47%. we describe an alternative approach to management of this difficult problem.

Aorta, Abdominal↗
PubMed1988

Systemic effects associated with intermittent claudication. A model to study biochemical aspects of vascular disease?

Patients with intermittent claudication were used as a clinical model to study the effects of transient episodes of ischaemia. Compared with age and sex matched controls significantly greater increases in serum lipid peroxides and urinary microalbumin occurred after exercise. These results suggest that even relatively minor ischaemic episodes, as occur with claudication, are sufficient to cause tissue damage which may be mediated by oxygen derived free radicals. There are also changes in renal permselectivity suggestive of a generalised increase in vascular permeability. These preliminary findings may have important diagnostic, aetiological and therapeutic implications for patients with vascular disease.

Aged↗
PubMed1988

Anastomotic arteriovenous fistulae--are they worth it?

An adjuvant distal arteriovenous fistula (ADAVF) has been claimed to increase arterial bypass graft flow and patency when run-off is poor but others have suggested that a patent fistula does not improve in distal limb perfusion. In 10 dogs, hind limbs were rendered ischaemic by proximal arterial ligations and then revascularised with vein grafts. In each dog an ADAVF was constructed on the left graft while the right was used as a control. Flow and pressure were measured in each graft and distal artery and the effect of temporary occlusion and release of the fistula noted. These measurements were repeated at re-operation 3 months later. Mean flow through control grafts was 83 +/- 8.57 (S.E.M.) ml/min, increasing to 146 +/- 22.89 (S.E.M.) ml/min with papaverine (P less than 0.001, Student's t test), and was unchanged at 3 months. Mean flow in grafts with a distal A-V fistula was 250 +/- 41.68 (S.E.M.) ml/min with no change after papaverine, and an increase to 730 +/- 110.5 (S.E.M.) ml/min at 3 months (P less than 0.001, Student's t test). However, arterial flow distal to the fistula was invariably retrograde at initial operation (20 +/- 3.0 S.E.M. ml/min), and this retrograde flow increased to 180 +/- 33.2 (S.E.M.) ml/min at 3 months (P less than 0.001, Student's t test). Distal arterial pressure at initial operation fell from 88.8 +/- 3.35 (S.E.M.) mmHg to 10.8 +/- 1.01 (S.E.M.) mmHg with the fistula open. We conclude that in this animal model an adjuvant distal arteriovenous fistula may improve bypass graft flow, but is unlikely to benefit distal limb perfusion.

Animals↗
PubMed1987

The anatomical basis for the route taken by Fogarty catheters in the lower leg.

The infrapopliteal route taken by Fogarty catheters when introduced through a common femoral arteriotomy is uncontrolled. We studied the passage of a catheter into the femoral artery in twenty cadavers and related the infrapopliteal route taken, to the angles of origin of the three crural arteries. We then attempted to modify the direction of travel of the catheter by manipulation. In 85% of cadavers the catheter passed into the peroneal artery on each of three consecutive passes, and the tip arrested at mid calf. In 75% of cadavers a 30 degrees bend to the tip of the catheter allowed passage into the posterior tibial artery in which case, the catheter could always be passed into the foot. In only one instance, when the angle of origin was unusually narrow, could the anterior tibial artery be entered.

Aged↗