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Biomedical subjects

I Faris

Publications and source records attributed to I Faris.

At least 19 recordsLinked to original sources
PubMed1995

The fate of the aortofemoral graft.

OBJECTIVE: To determine the incidence and cause for reoperation following aortofemoral bypass surgery. DESIGN: This paper describes the results of all aortofemoral grafts performed in the years 1978-1991, 251 of these patients underwent an aortobifemoral graft (ABF) whilst the remaining 50 had an aortounifemoral graft (AUF). RESULTS: The aortofemoral bypass was the only operation performed in fewer than half of the patients. Sixteen per cent of ABF and 50% of the AUF patients had surgery before the index operation. Subsequently 33% of the ABF patients and 60% of the AUF group had one or more additional vascular procedures. Graft infections and false aneurysms continued to present in about 1% patients per year at least up to 10 years following surgery. The 5 year actuarial survival was 73% in the ABF group and 38% in the AUF patients. The primary patency at 5 years was 85% in the ABF patients and 81% in the AUF group. Amputation was performed in 6% of the ABF patients and in 20% of the AUF patients. CONCLUSIONS: The frequent need for later surgery (1:3 for the ABF patients) should be considered in the decision to undertake the initial aortofemoral operation when the patient presents with intermittent claudication.

Aneurysm, False↗
PubMed1989

The veno-arteriolar reflex in free skin flaps.

The veno-arteriolar reflex was measured in 10 subjects in whom an area of denervated skin was present in the lower limb following free flap transfer of skin and subcutaneous tissue 3 weeks to 2 years previously. The vasoconstrictor response to dependency was measured in the skin of the flap, in adjacent innervated skin and after chemical dilatation of cutaneous vessels in the skin of the flap. This veno-arteriolar reflex resulting in a reduction of blood flow of 30-40% was present and equal in both normal and denervated skin. The response was abolished by chemical vasodilatation. The results indicate that sympathetic innervation is not essential for the veno-arteriolar reflex, and suggest that myogenic mechanisms may be more important than previously believed.

Adult↗
PubMed1987

Thrombolytic therapy.

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Arterial Occlusive Diseases↗
PubMed1986

Incidence of the radial steal syndrome in patients with Brescia fistula for hemodialysis: its clinical significance.

The Brescia fistula is the method of choice for providing vascular access in patients who have chronic kidney failure that requires hemodialysis. This study investigated hand hemodynamics in patients with Brescia fistulas to determine the incidence of radial steal and its relationship to symptoms of arterial insufficiency of the hand. Twenty-three patients, one of whom had symptoms of arterial insufficiency, were studied. Thumb systolic blood pressure was determined by photoplethysmography under resting conditions and with the fistula, radial, and ulnar arteries occluded successively by digital pressure. The brachial pressure was determined by Doppler ultrasonography and the thumb/arm pressure ratio was determined for each experimental condition. The presence of a Brescia fistula resulted in a 40% reduction of the thumb blood pressure (median thumb/arm ratio = 0.61), which returned to normal (median ratio = 1.03) when the fistula was occluded. Occlusion of the radial artery distal to the fistula resulted in a significant increase in thumb blood pressure (median ratio = 0.89; p less than 0.001), indicating the presence of radial steal. This phenomenon occurred in 21 of the 24 fistulas (88%) studied. This study demonstrated that the radial steal phenomenon occurs in most patients with Brescia fistulas but in only a small number of these patients do symptoms of arterial insufficiency develop.

Adult↗
PubMed1986

Intra-arterial streptokinase therapy to relieve acute limb ischemia.

One hundred two patients with acute lower limb ischemia were treated with intra-arterial streptokinase. Thirty-seven patients had occluded vascular grafts and sixty-five had had no previous vascular surgery. Eighty-six limbs were acutely threatened. Intra-arterial streptokinase was given as an initial loading dose with a lower maintenance dose given afterward. The mean duration of therapy was 59 hours and hematologic monitoring was meticulous. Indications for intra-arterial streptokinase therapy were contraindication to surgery, anticipation of technically difficult surgery, and multiple occlusions that required separate surgical approaches. Seventy-two legs were saved (71%) and 30 amputated. Morbidity was low and only 1 of the 11 deaths was attributable to streptokinase. No leg was lost that would otherwise have been saved by straightforward surgery and no leg was lost that had not been previously threatened. In 46 patients for whom emergency femorotibial bypass would have been necessary, 35 legs (76%) were saved. Forty-three patients had vascular reconstruction immediately after streptokinase therapy was stopped, to bypass occlusive lesions that had been demonstrated by the thrombolytic therapy in 28 patients, and because streptokinase had produced no response in 15 patients. The advantages of intra-arterial streptokinase in the management of the acutely ischemic leg are that the leg may be saved without surgery, that surgery is not precluded, that the patient can be made as fit as possible for surgery during the streptokinase infusion, and that streptokinase can facilitate surgery by delineating underlying vascular pathologic conditions and clearing distal runoff vessels.

Acute Disease↗
PubMed1985

Skin perfusion pressure in the prediction of healing in diabetic patients with ulcers or gangrene of the foot.

The measurement of skin perfusion blood pressure (SPP) estimated by an isotope clearance technique has been used to predict the healing of ulcers or gangrene of the foot in 61 diabetic subjects. Healing followed conservative treatment or local surgery in 1 of 21 cases if the SPP was less than 40 mm Hg but in 35 of 40 with higher values for SPP. Healing was unlikely if the toe blood pressure was less than 40 mm Hg or the ankle systolic pressure was less than 80 mm Hg. It is recommended that the SPP be measured in patients in whom confident predictions of healing cannot be made on the basis of ankle pressure or other measurements.

Adult↗
PubMed1984

Reconstructive renal vascular surgery for chronic renal failure.

This paper reports the results of reconstructive renal arterial operations on 23 patients who underwent surgery because it was considered that renal artery disease was contributing to their chronic renal failure. The median pre-operative serum creatinine in this group of patients was 0.77 (range 0.15-1.14 mmol/l) and all patients had severe hypertension. In 10 cases there was evidence of other renal disease (analgesic nephropathy, 8; glomerulonephritis, 2). Operation performed was unilateral aortorenal reconstruction in 21 patients and bilateral reconstruction in 2 patients. There were four in-hospital deaths. In 15 patients operation was judged to have improved their renal function with a fall of median pre-operative creatinine from 0.34 mmol/l (0.15-0.84) to a median creatinine of 0.15 (0.05-0.52). There was one intra-operative death. There were 7 patients in whom operation led to no improvement in renal function. Their median pre-operative creatinine was 0.90 (0.32-1.14 mmol/l), and this pre-operative creatinine differs significantly from the group whose creatinine fell after surgery (P less than 0.002). Renal artery reconstruction should be considered in patients with chronic renal failure who have correctable arterial lesions.

Adult↗
PubMed1984

Effect of therapy on 24-h subcutaneous blood flow in the leg in patients with severe ischemia.

The effect of vascular surgical reconstruction or Buerger's exercises upon average subcutaneous blood flow for a 24-h period was studied in 14 patients with severe leg ischemia due to occlusive arterial disease. Blood flow was estimated proximally in the calf and in the foot by a 133Xe washout technique. Seven patients underwent vascular surgery. Postoperatively subcutaneous blood flow increased in the calf and the foot in all patients except one in whom a decrease in blood flow in the foot was seen. In this case a decrease in systolic blood pressure occurred following the operation. Buerger's exercises did not alter subcutaneous blood flow either in the calf or in the foot in the seven patients studied. Buerger's exercises seem to be of no value for these patients. The measurement of blood flow in subcutaneous tissue over a period of 24 h seems to be a useful test of the effect of different treatments.

Aged↗
PubMed1984

Blunt injury to the subclavian artery.

This paper reports two cases of closed injury to the subclavian artery, one resulting from avulsion and the other from compression from a seat-belt. Diagnosis may be delayed because of the absence of both haemorrhage and distal ischaemia. The surgical approach may be via a standard supraclavicular incision, but frequently a combined cervicothoracic approach is necessary.

Accidents, Traffic↗
PubMed1984

Vascular disease and vascular function in the lower limb in diabetes.

This review examines the pathology, clinical effects and physiological disturbances produced by vascular disease and autonomic neuropathy in the lower limb in diabetic subjects. Atherosclerosis is a major factor in causing foot lesions in diabetics. The distribution of the disease frequently makes vascular reconstructive surgery difficult or impossible but an aggressive approach to reconstruction is justified because the results of major amputations are bad. Arterial calcification probably has no significant effect on the blood supply to the foot. There is some evidence that disease of arteries in the foot may be associated with the development of ulcers or gangrene. Disease of the arterioles and capillaries is frequent, but there is little evidence that this microangiopathy causes lesions. Autonomic neuropathy affecting the limb is also common, and although there are several mechanisms by which this might predispose to ulcers or gangrene, there is little evidence of such a direct relationship. In a patient presenting with ulceration or gangrene of the foot it is often impossible to determine the relative roles of vascular disease, affecting large or small vessels, and neuropathy, either somatic or autonomic, in the development of the lesion. Further progress depends on the development of more direct methods for assessing microvascular and autonomic nervous function.

Arteriosclerosis↗
PubMed1983

Impaired autoregulation of blood flow in skeletal muscle and subcutaneous tissue in long-term Type 1 (insulin-dependent) diabetic patients with microangiopathy.

Autoregulation of blood flow was studied in skeletal muscle and subcutaneous tissue in seven Type 1 (insulin-dependent) diabetic patients (median age: 36 years) with nephropathy and retinopathy and in eight normal subjects of the same age. Blood flow was measured by the local 133Xe washout technique. Reduction in arterial perfusion pressure was produced by elevating the limb 20 and 40 cm above heart level. Blood flow remained within 10% of control values when the limb was elevated in normal subjects. In five of the seven diabetic subjects blood flow fell significantly in both tissues when the limb was elevated 40 cm indicating impaired autoregulation. The results suggest that intrinsic vascular (arteriolar) mechanisms (myogenic and/or metabolic) underlying the normal autoregulatory response are defective in some diabetic patients with microangiopathy.

Adult↗
PubMed1983

Popliteal artery puncture in the assessment of patients with severe leg ischemia.

Two-plane angiography and direct segmental pressure measurements in the femoral and popliteal arteries and indirectly on the arm and ankle were performed in 101 limbs seeking to establish a relationship between angiographic assessment of the patency of the popliteal artery and the trifurcation vessels and the popliteal ankle pressure difference. When the tiberoperoneal trunk or the trifurcation vessels were occluded or more than 50% of the lumen was stenosed, the pressure difference exceeded 10 mmHg in 30/40 limbs (75%). When three, two, or only one of the tibial vessels were patent, the pressure difference exceeded 10 mmHg in 2/58 limbs (3%). One month following above knee femoropopliteal bypass (48 limbs), patients with a popliteal-ankle difference less than 10 mmHg obtained a significantly higher ankle pressure index (PI 0.86, range 0.56-1.20) (p less than 0.01) than those with a pressure difference exceeding 10 mmHg (PI 0.66, range 0.40-0.91). The clinical state 6 months following femoropopliteal bypass did not demonstrate that patients with a low popliteal-ankle difference fared better than patients with a higher pressure difference; however, the PI appeared significantly lower in the latter group compared to the former. The graft material was correlated to the popliteal-ankle pressure difference. It appeared that prosthetic grafts failed within 6 months when the difference exceeded 10 mmHg in 10/12 limbs (83%), but autologous vein grafts only failed in 2/10 limbs (20%). Finally, it was possible to predict the postoperative ankle pressure index significantly from data derived from the pressure measurements.

Adult↗
PubMed1983

Evidence for a local sympathetic venoarteriolar "reflex" in the dog hindleg.

The study was performed in order to determine whether a local sympathetic venoarteriolar "reflex" is present in the dog hindleg. Femoral artery blood flow was measured by an electromagnetic flowmeter probe, and blood flow in the thigh muscle and subcutaneous tissue distally in the paw was measured by the local 133Xe washout technique. Twenty experiments were carried out in seven dogs unilaterally sympathectomized 2-4 weeks previously. Resting vascular tone did not differ in the sympathectomized and nonsympathectomized legs. In the control leg, venous pressure elevation caused a decrease in femoral blood flow of 49% corresponding to an increase in vascular resistance of 58%. In muscle and subcutaneous tissue vascular resistance increased by 81% and 35%, respectively. In the denervated leg, venous stasis caused no change in total vascular resistance. In muscle the vascular resistance increased by only 24%. In subcutaneous tissue, vascular resistance decreased by 12%. The effect of acute lumbar sympathectomy was studied in another group of seven dogs. Operation caused an immediate decrease in vascular resistance of 40%. The increase in vascular resistance during venous stasis in the total leg, as well as in muscle and subcutaneous tissue, was not affected. However, acute lumbar sympathectomy combined with injection of phenoxybenzamine into the femoral artery almost abolished the vasoconstriction induced by venous stasis. In muscle, the increase in vascular resistance was still present, but considerably attenuated. In subcutaneous tissue, the normal response was completely blocked. Finally, local suction induced vasoconstriction in an adjoining area not subjected to changes in vascular transmural pressure, an effect that could be blocked by local neural blockade at the site of suction. The results strongly suggest that a local sympathetic veno-arteriolar (axon) "reflex" is present in muscle and subcutaneous tissue in the dog hindleg.

Animals↗
PubMed1983

Hemodynamic factors as a cause of vascular surgery failures in diabetics.

Thirty-six legs in thirty-three diabetic patients with ischemia at rest and multiple level arterial disease were studied preoperatively. Direct intraarterial femoral and popliteal artery blood pressures were measured together with indirect arm and foot blood pressures. Based on the systolic segmental pressure gradients it was predicted preoperatively whether it was necessary to make a one- or two-level reconstruction. The ankle pressure measured one month postoperatively correlated well with predicted values. Of the seventeen occlusions within the observation time hemodynamic factors played an important role in eleven cases. In the femoro-crural segment one occluded in which an iliac stenosis with a pressure gradient of 28% had been disregarded. In the femoro-popliteal above knee segment four occlusions occurred in cases where the postoperative ankle pressures were less than 80% of the preoperatively predicted value, suggesting stenosis at the anastomosis. A popliteal to ankle gradient of 39% was measured preoperatively in the fifth case which occluded 2 months postoperatively. In the aortofemoral segment five occlusions occurred all having femoral to ankle pressure gradients exceeding 40% of femoral artery pressure. Retrospectively, seven of the failures might have been prevented by two-level reconstructions and four failures by a secondary arterioplasty.

Adult↗
PubMed1982

Decreased distensibility of a passive vascular bed in diabetes mellitus: an indicator of microangiopathy?

This study was undertaken to determine whether the distensibility of a passive vascular bed is reduced in Type 1 (insulin-dependent) diabetic patients with microangiopathy. The change in blood flow induced by 45 degrees head-up tilting was studied in two systems: (a) following maximal ischaemic exercise and (b) in a vascular bed locally paralysed by the injection of papaverine. Five normal subjects, six patients with long-standing Type 1 diabetes and six non-diabetic patients with severe atherosclerosis affecting the legs were studied. Blood flow was measured in the anterior tibial muscle by the isotope washout technique. The median increase in blood flow produced by tilting was greater in normal subjects than in diabetic subjects in both the locally-relaxed bed (58% and 14% respectively) and after maximal ischaemic exercise (45% and 4% respectively). In the atherosclerotic subjects, the increase in blood flow in the locally relaxed bed was 77%. The results are consistent with the hypothesis that the reduced distensibility seen in the diabetic subjects was related to the presence of microvascular disease and that the behaviour of a vascular bed relaxed by the local injection of papaverine might be an appropriate model to study this condition.

Adult↗