Severe Leg Ischemia Research Articles

Aortopopliteal Bypass Via Obturator Foramina for Limb Salvage After Failed Previous Iliofemoral, Femorofemoral, Femoral-Popliteal Bypasses

A 65-year-old man with right iliac artery occlusion, left iliofemoral stenosis, and bilateral superficial femoral arteries occlusion, instead of receiving the traditional aortofemoral bypass, underwent in sequence the following operations: left common iliac to femoral bypass, femorofemoral bypass, and bilateral femoropopliteal bypasses with use of polytetrafluoroethylene (PTFE) grafts. Occlusion of the femoropopliteal bypass and stenosis of the iliofemoral bypass at the distal anastomosis resulted in severe leg ischemia with nonhealing toes and leg ulcers. To minimize ischemia time to the lower extremities, pelvic organs, and kidney and avoid the need for multilevel revascularization, the patient received aortobipopliteal bypass via obturator foramina. The aortic anastomosis was intentionally constructed in and end-to-side fashion to avert the need for left accessory renal artery implantation and interruption of the pelvic arterial supply. The patient has palpable ankle pulses and progressed to heal the ischemic ulcers following the aortobipopliteal bypass operation.

Durability of angioplasty in treating severe leg ischaemia

Abstract Background Percutaneous transluminal angioplasty (PTA) has recently been accepted as a valuable therapeutic option in patients with severe limb ischaemia. However, despite the increasing use of this technique, there have been concerns that the long-term efficacy of PTA is inferior to that of surgical revascularization. This prospective study reports the outcome of an unselected cohort of patients who underwent balloon angioplasty for severe lower limb ischaemia in a single centre. Methods During 1997, 108 patients with 133 severely ischaemic legs were treated by PTA. The median age of the patients (49 per cent men) was 76 years. Symptoms were rest pain in 31 per cent, ischaemic ulceration in 56 per cent and gangrene in 13 per cent. The distribution of risk factors was typical: diabetes 32 per cent, ischaemic heart disease 18 per cent and stroke 16 per cent. Median (interquartile range) follow-up was 16 (12–19) months. There was a mean of 1·7 angioplasty sites per patient, distributed in the iliofemoral (14 per cent), superficial femoral (42 per cent), popliteal (18 per cent) and crural (26 per cent) arteries. PTA was performed luminally in 20 per cent of cases and subintimally in the remainder. Overall, 67 per cent of the lesions were complete occlusions with a median length of 20 (10–40) cm. Results Technical success was achieved in 104 limbs, with 29 failures. The outcome of patients with a failed angioplasty (29) was poor, with 14 requiring bypass surgery, 11 undergoing a major amputation and 32 per cent dying after the procedure. In contrast, patients having a technically successful angioplasty had a good outcome after a median follow-up of 16 (12–19) months. In this group there was a 30 per cent overall mortality rate during follow-up. However, 85 per cent of the patients had no symptoms of critical ischaemia and the limb salvage rate was 92 per cent. Conclusion PTA is an effective and durable procedure in patients with critical leg ischaemia, with results comparable to those of historical surgical controls. Technical failure of PTA is, however, associated with a dire outcome.

INTRAVASCULAR ULTRASOUND ANGIOPLASTY IN PERIPHERAL ARTERIAL OCCLUSION. Preliminary experience

Purpose: To determine if ultrasound angioplasty in a percutaneous approach was capable of recanalizing occluded arteries in acute and subacute peripheral arterial occlusions. Material and Methods: We applied an ultrasound angioplasty device in a percutaneous approach in 9 patients with peripheral arterial occlusions. All patients suffered from severe leg ischemia due to subacute thrombotic occlusions. Results: The ultrasound transmitter easily created a channel within the occlusive material. To further reduce the mass of the occlusive material, an aspiration thrombectomy was performed in all cases, leading to a complete recanalization in 7 cases. In 2 cases, a remaining stenosis was successfully dilated. Conclusion: Intravascular ultrasonic devices can be useful for recanalization of occluded peripheral arteries. In particular, if thrombolytic therapy of longer peripheral arterial occlusions fails or is contraindicated, ultrasound angioplasty may be a new approach for recanalization.

Intravascular ultrasound angioplasty in peripheral arterial occlusion. Preliminary experience.

To determine if ultrasound angioplasty in a percutaneous approach was capable of recanalizing occluded arteries in acute and subacute peripheral arterial occlusions. We applied an ultrasound angioplasty device in a percutaneous approach in 9 patients with peripheral arterial occlusions. All patients suffered from severe leg ischemia due to subacute thrombotic occlusions. The ultrasound transmitter easily created a channel within the occlusive material. To further reduce the mass of the occlusive material, an aspiration thrombectomy was performed in all cases, leading to a complete recanalization in 7 cases. In 2 cases, a remaining stenosis was successfully dilated. Intravascular ultrasonic devices can be useful for recanalization of occluded peripheral arteries. In particular, if thrombolytic therapy of longer peripheral arterial occlusions fails or is contraindicated, ultrasound angioplasty may be a new approach for recanalization.

Optimisation of the Non-invasive Assessment of Critical Limb Ischaemia Requiring Invasive Treatment

Objective: to assess the optimal cut-off values of toe blood pressure (TBP) and transcutaneous oxygen pressure (TcpO2) in the supine and sitting positions, in order to accurately detect the presence of severe leg ischaemia requiring invasive treatment. Methods: in 49 consecutive patients (65 legs) with severe ischaemia according to clinical symptoms of Fontaine III or IV and a lowered ankle blood pressure, TBP and TcpO2were measured in the supine and sitting positions. Treatment within 6 weeks after the diagnosis was classified as either conservative or invasive (revascularisation or amputation). Results: of the 65 legs, 38 (58%) required invasive treatment. The mean ankle pressure for this group was 70 mmHg. The optimal cut-off value for TBP was 38 mmHg and for TcpO235 mmHg. A TBP of ≤30 mmHg and a TcpO2≤25 mmHg while supine, showed likelihood ratios (LR) of 7.0 and 3.3, respectively, and when combined an LR of 12.4. Measurements in the sitting position did not enhance diagnostic power. Conclusions: the need for invasive therapy in patients with severe leg ischaemia might be predicted by measuring TBP and TcpO2, using the above-mentioned cut-off values.

Smoking, hemorheologic factors, and progression of peripheral arterial disease in patients with claudication

Purpose: The purpose of the current study was to determine whether hemostatic and rheologic factors are associated with the deterioration of peripheral arterial disease in patients with intermittent claudication and the influence of smoking and severity of underlying disease on these relationships. Methods: We conducted a prospective cohort study with a 6-year follow-up period of a consecutive series of 607 patients with uncomplicated intermittent claudication. The study setting was the Peripheral Vascular Clinic, Royal Infirmary of Edinburgh. The main outcome measures were peripheral vascular intervention or onset of severe chronic leg ischemia (rest pain, ulceration, gangrene). Results: A total of 210 patients died during follow-up. Two hundred three patients did not have a vascular event or deterioration of limb ischemia, 45 patients underwent a peripheral vascular intervention, and 64 progressed to severe chronic leg ischemia. Median levels (interquartile ranges) of whole blood viscosity were significantly higher in the vascular intervention group (3.75 mPa/sec; range, 3.38 to 4.13 mPa/sec) than in those who did not deteriorate 3.48 mPa/sec; range, 3.06 to 3.83 mPa/sec) ( p ≤ 0.05), and plasma von Willebrand factor was higher in those with severe chronic leg ischemia (154.0 IU/dl; range, 122.0 to 187.0 IU/dl) than in those who did not deteriorate (131.0 IU/dl; range, 106.0 to 165.0 IU/dl) ( p ≤ 0.01). After adjustment for age, sex, cigarette smoking, and ankle brachial pressure index, the levels of plasma fibrinogen and blood and plasma viscosities were each associated with an increased risk of vascular intervention (all p ≤ 0.05). There were no significant associations between any of the hemorheologic factors and the risk of severe chronic leg ischemia on multivariate analyses. Conclusion: Elevations in rheologic factors may have important effects on further reduction of blood flow in the legs of patients with claudication and promote worsening ischemia and clinical progression of symptoms.(J Vasc Surg 1998;28:129-35.)

Prospective randomized trial of high-dose bolus versus low-dose tissue plasminogen activator infusion in the management of acute limb ischaemia

Accelerated thrombolysis with high-dose bolus tissue plasminogen activator (tPA) may enable patients with more severe acute leg ischaemia to be treated without recourse to surgery. This study was a randomized comparison of two thrombolytic regimens. One hundred patients with acute leg ischaemia of less than 30 days' duration were randomized to receive either high-dose bolus tPA (three doses of 5 mg over 30 min, then 3.5 mg/h for up to 4 h, then 0.5-1.0 mg/h) or conventional low-dose tPA (0.5-1.0 mg/h). The groups were well matched for age, cardiovascular risk factors, duration and severity of ischaemia, site, cause and length of arterial occlusion. The median duration of infusion in the high-dose group was 4.0 (range 0.25-46) h compared with 20 (range 2-46) h for low-dose infusion (P < 0.0001). Successful thrombolysis was achieved in 45 of 49 high-dose and 39 of 44 low-dose infusions but significantly more adjunctive procedures were required following high-dose bolus infusion (26 versus 16 patients) (P = 0.002). Thirty days after treatment was commenced, limb salvage was achieved in 39 of 49 patients in the high-dose group compared with 37 of 44 who had a low-dose infusion of tPA. Six and two patients respectively required amputation. Four patients in the high-dose group and five in the low-dose group died. Three patients in each group suffered a major haemorrhage and one in the low-dose group had a stroke. High-dose bolus therapy significantly accelerated thrombolysis with tPA without compromising outcome. Some 50 per cent of patients were treated within 4 h enabling thrombolysis to be used as primary therapy for patients with acute critical ischaemia.

The predictive value of laser Doppler fluxmetry and transcutaneous oximetry for clinical outcome in patients undergoing revascularisation for severe leg ischaemia

To investigate the predictive value of laser Doppler fluxmetry and transcutaneous oximetry in 41 patients undergoing technically successful revascularisation for severe leg ischaemia. Toe and ankle systolic arterial pressures, transcutaneous oxygen tension (tcpO2), and stressed laser Doppler fluxmetry at the foot (time to peak laser Doppler flux following 2 min arterial occlusion, tp LDF, and the response of LDF to raising the leg 40 cm, the elevated:supine LDF ratio) were measured before revascularisation. Six months later these measurements were compared in those patients who were clinically improved, and those who still had symptoms of severe ischaemia or had lost their limb. Vascular Laboratory, St. George's Hospital, London SW17, U.K. Six months following revascularisation 30 (73%) of the 41 patients had partial or complete symptomatic relief. Six (15%) had undergone major amputation and five (12%) still had symptoms of severe ischaemia. Before intervention toe and ankle systolic pressures were similar in the 30 who were improved and the 11 who had lost, or were still at risk of losing, their leg. Pre-revascularisation tcpO2 was significantly lower (18.3 mm Hg vs 33.5 mm Hg; p < 0.05) and tp LDF significantly longer (140 s vs 92 s; P < 0.05) in the 11 patients who were not clinically improved at 6 months. Whilst pre-revascularisation toe and ankle pressures below 30 mm Hg and 50 mm Hg respectively identified only 55% of those patients who were not improved 6 months later, a tp LDF in excess of 100 s identified 82% (p < 0.05) and was noted in five of the six amputees. Microcirculatory assessments performed in patients with limb-threatening ischaemia are likely to be more deranged in those patients who suffer clinical failure or amputation despite an apparently successful revascularisation procedure.

Prostanoid drug therapy for peripheral arterial occlusive disease--the European experience.

The most serious threat to a claudicant is not the possible future need for a major amputation, but rather that the medium-term mortality is two to three times that of the general age-matched population. In patients with more severe disease in the legs, approximately 45% will have had a major amputation or be dead within a year of developing rest pain, ulcers or gangrene. These are the challenges for pharmacotherapy in peripheral arterial occlusive disease. In the short and medium term, pharmacotherapy can only have a significant effect by modifying the microcirculatory response to the low perfusion pressure caused by the arterial disease. The microcirculatory changes in the leg in severe leg ischaemia are ill understood, but theoretically a number of pharmacological effects could be beneficial. In practice, the only type of drugs widely tested clinically in severe leg ischaemia are prostacyclin and its analogues. In the last 12 years the results of properly controlled randomized trials involving patients with chronic limb ischaemia have been carried out in approximately 2000 patients in Europe. The largest number were entered into trials using the prostacyclin analogue iloprost. Some of these trials have shown a significant benefit compared to placebo in terms of major amputation or death during the 6 months following a 2-4 week course of intravenous iloprost. The possible future indications for this type of therapy, as well as the use for prostaglandins in claudicants, is discussed.

Effects of spinal cord stimulation (SCS) in patients with inoperable severe lower limb ischaemia: A prospective randomised controlled study

This study was designed to test the hypothesis that spinal cord stimulation (SCS) improves limb salvage in patients with inoperable severe leg ischaemia. Prospective randomised controlled study with 18 months follow-up. Vascular surgical units in two university hospitals. Atherosclerotic (n = 41) and diabetic (n = 10) patients having chronic leg ischaemia with rest pain and/or ischaemic ulcerations due to technically inoperable arterial occlusions. Limb salvage and amount of tissue loss within 18 months, pain relief. Twenty-five patients were randomized to SCS and 26 to analgesic (control) treatment. Macrocirculatory parameters were not different in the two groups during follow-up. Long-term pain relief was observed only in the SCS group. At 18 months, limb salvage rates in the SCS and control groups were 62% and 45% (N.S.). Tissue loss was less (p = 0.05) in the SCS group. A subgroup analysis of patients without arterial hypertension showed a significantly lower amputation rate in the SCS vs the control group. SCS provided long-term pain relief but limb salvage at 18 months was not significantly improved by SCS in this rather small study. The results suggest that SCS may reduce amputation levels in patients with severe inoperable leg ischaemia and be most effective in patients without arterial hypertension.

Falsely elevated ankle pressures in severe leg ischaemia: The pole test—An alternative approach

Ankle-branchial pressure indices (ABPIs), measured by sphygmomanometer and Doppler probe, are an accepted index of chronic leg ischaemia. However, tibial artery sclerosis or calcification decreases compliance, producing falsely elevated cuff occlusion pressures. Arterial cannulation is invasive and impractical, but by elevating the foot and measuring the height at which the Doppler signal disappears, ankle systolic pressure in mmHg can be derived. Using an 8MHz Doppler apparatus and calibrated pole, ankle systolic pressures measured by sphygmomanometer and elevation were compared in 49 severely ischaemic legs (40 patients). ABPIs were derived by dividing ankle systolic pressure by brachial pressure. Median (interquartile range) ABPI assessed by sphygmomanometry was 0.46 (0.35-0.56). Median ABPI measured by leg elevation was significantly lower at 0.21 (0.14-0.30), p < 0.0001, Wilcoxon. In 20 patients undergoing in situ vein bypass grafting, direct transducer-derived pressure measurements were obtained. Median ABPI for this method was 0.15 (0.11-0.27). No significant difference was found when compared with ABPIs derived by elevation, median 0.2 (0.13-0.31), p = 0.324, however median ABPI measured by sphygmomanometry was significantly higher at 0.37 (0.27-0.6), p = 0.0008. Correlation of elevation with transducer-assessed pressure measurements (r = 0.88) was closer than with cuff-derived measurements (r = 0.69). Pressures derived by leg elevation provide a more accurate index of severe leg ischaemia than sphygmomanometry, although the technique is limited to assessing pressures of less than approximately 60 mmHg. Falsely elevated ABPIs may underestimate the extent of disease in patients assessed for vascular reconstruction.

Combined coronary and femoral revascularization using an ascending aorta to bifemoral bypass.

Coronary artery and aortoiliac disease frequently coexist. In rare instances simultaneous procedures may be required. This study reports our experience with ascending aorta to bifemoral bypass. Prospective consecutive sample study. Ten male patients who underwent concomitant aortoiliac and coronary revascularization with the ascending aorta as the source of inflow to the femoral arteries between 1989 and 1991. One hospital death was unrelated to the surgical technique. All survivors displayed an uneventful recovery and were free of symptoms. Follow-up was obtained in all nine cases, they all stayed asymptomatic in terms of coronary artery disease and peripheral vascular disease. Echo-doppler studies showed perfect patency of the aorto-femoral grafts in all cases. This study shows that the ascending aorta to bifemoral bypass constitutes an interesting alternative in selected cases mainly those with severe ischemia coronary and leg ischemia. It offers the following advantages: (1) it is easy to perform, (2) does not require an intraperitoneal procedure, (3) the graft's position behind the muscles of the abdominal wall is not compressible, (4) the ascending aorta is the source of inflow, and (5) it allows a shorter duration of hospital stay.

Capillary recruitment and pain relief on leg dependency in patients with severe lower limb ischemia.

Patients suffering from severe lower limb ischemia may experience pain relief on leg dependency despite the fact that dependency normally results in arteriolar vasoconstriction. To clarify this possible paradox, skin microcirculation of the limb was investigated in 75 patients with different stages of lower limb ischemia and in 12 asymptomatic subjects. Using nailfold capillary video microscopy, red blood cell-perfused capillary density and diameter and red blood cell velocity were assessed in supine and sitting positions. Capillary density increased by changing from the supine to the sitting position, especially in patients with limb-threatening ischemia (showing a 4.5-fold increase versus a 1.5-fold increase in asymptomatic subjects). In subjects without or with mild ischemia, capillary perfusion was two to four times lower in the sitting than in the supine position. In patients with limb-threatening ischemia, perfusion was strongly reduced, being slightly higher in the sitting position. Patients with relief of pain while sitting did not always have a higher capillary perfusion but did have a higher capillary density in the sitting position. The arteriolar postural vasoconstrictive mechanism at the nutritive level is still intact in subjects without or with mild ischemia but not in patients with severe ischemia. Capillary recruitment rather than disturbed arteriolar vasoconstriction could explain why patients with severe leg ischemia prefer leg dependency.

Posturally induced microvascular constriction in patients with different stages of leg ischaemia: effect of local skin heating.

1. Skin microcirculation was investigated in 12 asymptomatic subjects and 76 patients, grouped according to their ankle-to-brachial systolic blood pressure index, in order to evaluate to what extent posturally induced microvascular constriction is dependent on the stage of leg ischaemia at different local skin temperatures. 2. Skin microcirculation was assessed in the supine and sitting position by using laser Doppler fluxmetry at unheated skin temperature and at 36 degrees C, and transcutaneous oximetry at 37 degrees C and 44 degrees C. 3. Skin perfusion and oxygenation diminished with decreasing ankle-to-brachial systolic blood pressure index. In healthy control subjects, perfusion and oxygenation were reduced when changing from the supine to the sitting position, but were enhanced in patients with severe leg ischaemia (ankle-to-brachial systolic blood pressure less than 30%), indicating disturbed posturally induced vasoconstriction. 4. Increasing the local skin temperature resulted in a higher perfusion and masked the posturally induced vasoconstriction in healthy subjects. In patients with severe leg ischaemia, however, perfusion was unaltered by the temperature increase, apparently because the microvessels were already maximally dilated. The induction of reactive hyperaemia produced no additional increase in perfusion or oxygenation. 5. It is concluded that posturally induced microvascular constriction in the skin is disturbed in patients with severe leg ischaemia (ankle-to-brachial systolic blood pressure index less than 30%). Disturbed microvascular constriction upon dependency was also seen in healthy subjects after local skin heating. This suggests that posturally induced vasoconstriction is mainly regulated by local mechanisms.

Abnormal flow properties of white blood cells in patients with severe ischaemia of the leg.

The possible role of white blood cells in tissue ischaemia has attracted recent interest. White blood cells can block narrow vessels, particularly if perfusion pressure is reduced or if the cells become activated. To investigate the role of white blood cells in ischaemia microfiltration techniques were used to measure the flow properties of these cells in patients with severe leg ischaemia before and after amputation. Compared with controls white blood cells from patients showed impaired ability to flow through 8 micron and 5 micron pore filters. This applied to fractionated granulocytes and mononuclear cells as well as to unfractionated mixed white blood cells. White blood cells from blood draining the ischaemic leg had worse filterability than those from arm blood of the same patients. After amputation of the ischaemic leg there was definite improvement, the flow properties of the cells being no longer significantly different from controls. These abnormalities detected in white blood cells probably reflect activation of the cells by factors released in the ischaemic tissue. As activation alters the mechanical and adhesive properties of white blood cells, a vicious cycle of microcirculatory trapping at low perfusion pressure, activation, tissue damage, and further activation and trapping might contribute to the progressive worsening of tissue ischaemia.

Intraaortic balloon pump insertion: A randomized study comparing percutaneous and surgical techniques

To compare the percutaneous and surgical techniques of intraaortic balloon pump insertion, 101 patients referred for this procedure were randomly assigned to either percutaneous or surgical insertion. Insertion using the designated technique was successful in 45 (88%) of 51 patients with percutaneous insertion and 48 (96%) of 50 patients with surgical insertion (difference not statistically significant). The time from the beginning of the insertion procedure to the initiation of counterpulsation was 13 +/- 8 minutes for the percutaneous technique versus 31 +/- 16 minutes for the surgical technique (p less than 0.001). In the percutaneous group, 10 patients required Fogarty thrombectomy after balloon pump removal, and 1 patient developed severe leg ischemia requiring immediate termination of balloon pump support. In the surgical group, one patient developed leg ischemia requiring surgical intervention, three patients developed sepsis with bacteremia (including one patient who required vein patch repair of the femoral artery), one patient developed a wound infection requiring debridement and one patient had a cerebral embolus. Aortic dissection, aortoiliac perforation or amputation did not occur in either group. Major vascular complications occurred in 11 patients (22%) with percutaneous insertion versus 2 patients (4%) with surgical insertion (p less than 0.05). It is concluded that although the percutaneous technique for intraaortic balloon pump insertion is faster than the surgical technique and is technically easy, it is associated with a higher incidence of vascular complications.

Trends in Revascularization of the Lower Extremity

Several trends are evident in revascularization of the lower extremity. Currently, few patients with severe leg ischemia undergo amputation without prior surgical or angioplasty attempts at revascularization. Percutaneous balloon angioplasty and thrombolytic therapy have had a definite but limited influence on the treatment of all patients with lower-limb arterial disease. Although pentoxifylline, a hemorrheologic agent, is being widely used, it has not changed the need for surgical intervention in patients with severe arterial disease. In the aggressive approach to save legs with severe popliteal-tibial disease, the use of femorotibial grafts is increasing. In situ saphenous vein grafting is becoming the operation of choice for infrapopliteal occlusive disease. For most patients with severe lower-extremity arterial occlusive disease, a properly selected and conducted operation remains the safest and most durable treatment.

Crural Arterial Reconstruction with an Adjunct Arteriovenous Fistula for Limb Salvage

Twenty-one femoro-crural bypass procedures with a distal arteriovenous fistula (dAVF) were constructed in 20 patients with severe leg ischemia (Fontaine stage III, IV). They were followed-up for 3 to 22 months, with a mean of 8 months. The 15 patients with patent grafts and fistulas no longer had pain at rest; ischemic necroses healed. Telethermography showed a considerable augmentation of the distal limb perfusion. The mean increase of the transcutaneous oxygen pressure was 30 mmHg. One early postoperative amputation was necessary due to graft infection. Another patient lost her leg because of bypass occlusion 9 months after arterial reconstruction. Four patients with late graft occlusion kept their regained mobility and alleviation. Our data confirm experimental results suggesting that femoro-crural bypass with a dAVF improves distal leg perfusion by reversal venous blood flow and stimulation of a collateral network. Femoro-crural bypass with a dAVF may be of benefit in selected cases when only one crural artery is patent and pedal arch vessels are absent.

Serotonin and the Flow Properties of Blood

The effects of serotonin and its pharmacological antagonists on the physical flow properties of the blood have been studied far less than their effects on blood vessels, although they may be equally important. Indirect evidence suggests that in pathological circumstances serotonin may locally increase whole blood viscosity, particularly at low shear rates, decrease red cell deformability and increase the adhesiveness of white cells. Although the viscosity of the plasma alone is not affected, the rheological effects of serotonin on blood cells is probably dependent on the presence of platelets. These mechanisms may have a systemic effect in some forms of hypertension as well as in situations of local ischaemia such as Raynaud's phenomenon, atherosclerotic pregangrene of the leg or acute myocardial infarction. Specific serotonergic-antagonists, administered either orally or intravenously, normalize the increased whole blood viscosity and decreased blood filterability found in essential hypertension, following myocardial infarction and in severe leg ischaemia. The effect on red cell deformability is usually greatest when the cells are resuspended in platelet rich plasma. Ketanserin given intravenously for seven days to patients with very severe leg ischaemia, significantly improves whole blood viscosity, increases red cell transit time and most dramatically decreases pore clogging. This last effect was at least partly due to a change in the physical properties, but not the number of the white cells. The reported beneficial clinical effects of such an antagonist in various forms of peripheral ischaemia and essential hypertension may well be due, at least partly, to the normalization of the rheological properties of the blood.

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.