Comparison of transcutaneous oximetry, vascular hemodynamic measurements, angiography, and clinical findings to predict the success of peripheral vascular reconstruction

The present study examined prospectively the prognostic value of preoperative clinical findings, angiography, and conventional vascular hemodynamic and transcutaneous oximetry measurements in a consecutive series of patients undergoing lower extremity vascular reconstruction. A total of 25 variables were independently evaluated in each limb. Follow-up at least 6 months after operation was carried out in all patients. The postocclusive transcutaneous oxygen recovery time was found to be the most accurate predictor of short-term femoropopliteal bypass graft success. Preoperative foot transcutaneous oxygen recovery time values were significantly worse in patients whose femoropopliteal bypass grafts failed than in those in whom the outcome was successful (p less than 0.03). Transcutaneous oxygen recovery time values were also valuable in patients who underwent aortofemoral bypass; patients with isolated aortoiliac disease had significantly better foot transcutaneous oxygen recovery time values than those with combined aortoiliac and femoropopliteal disease (p less than 0.05). Foot transcutaneous oxygen recovery time values were also found to correlate well with the severity of symptoms (p less than 0.01), as did ankle-brachial Doppler pressure indices. Although the other variables analyzed provided useful diagnostic information, none were as accurate as the postocclusive transcutaneous oxygen recovery time in predicting the outcome of peripheral vascular reconstruction. As a means of more accurately classifying patients with peripheral vascular disease, we recommend the complimentary use of clinical findings, angiography, and hemodynamic and transcutaneous oximetry measurements. Because transcutaneous oxygen tension reflects the balance between local oxygen supply and demand, it may help to better define risk factors preoperatively in physiologic terms.

Palpation of the femoral and popliteal pulses: a study of the accuracy as assessed by agreement between multiple observers

Six vascular surgeons independently examined 44 legs in patients with suspected peripheral arterial disease. Each surgeon recorded whether the femoral and popliteal pulses were present or absent, and if thought to be present, whether they were normal or reduced in amplitude. Interobserver agreement was determined by calculating both observed agreement (Po) and agreement after correction for chance (kappa-k). The results were calculated both for each possible pair of surgeons and as an overall value for all possible pairs combined. Agreement as to whether pulses were present or absent was significantly better than expected by chance but was only moderately good (overall kappa for femoral pulse = 0.53, and overall kappa for popliteal pulse = 0.52). More often than not, agreement as to whether the pulses were normal or reduced was no better than expected by chance (overall kappa for femoral pulse = 0.15, and overall kappa for popliteal pulse = 0.01). For each assessment, agreement was no better for the more experienced than the less experienced pairs of surgeons. The results indicate that more objective methods than pulse palpation are required to determine whether there is significant disease in the aorto-iliac and femoro-popliteal arterial segments.

The place of profundaplasty in the surgical treatment of superficial femoral artery occlusion

One-hundred and sixty-three patients in whom an isolated profundaplasty was performed as treatment for superficial femoral artery occlusion were evaluated for postoperative improvement, taking into consideration the degree of stenosis of the profunda origin and the patency of peripheral vessels. One-hundred and eleven (68.1%) patients achieved clinical improvement. Fifty-two patients had to undergo amputation (27 below the knee and 19 above the knee) or distal reconstruction (6 patients) because of unrelieved ischaemia. In patients with Fontaine stage II and III disease (89% and 70% respectively) improvement was observed more often than in those with stage IV disease (53%). Half of the patients had an increase of the resting systolic ankle-brachial arterial pressure index, but the rise was only slight (0.12 +/- 0.1). While radiological information of the presence and degree of a stenosis had little influence on the operative outcome stenosis at the origin of the profunda, when seen and described at operation, resulted in a more frequent improvement in the clinical state and systolic ankle-brachial arterial pressure index. A patent popliteal artery was not necessary for a favourable outcome but the number of patent tibial arteries was important. Whenever two tibial vessels were patent, relief was achieved in 75% of the cases: the existence of one patent tibial artery produced improvement in 64% but if all were occluded only 31% showed improvement. In cases of severe ischaemia, success following profundaplasty is limited and the results are often inadequate. If at least one tibial artery is patent, the alternative is a femoro-crural reconstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamics of in situ vein bypass: the role of side branch fistulae

Ten patients undergoing femoral-popliteal and femoral-tibial in situ saphenous vein bypass for limb salvage were studied to determine the effects of side branch arteriovenous fistulae on flow through the distal end of the graft into the outflow artery. Studies were performed intraoperatively with electromagnetic flow probes. Following completion of proximal and distal anastomoses, flow was established through the graft and measured through its proximal and distal ends. Side branches were then ligated, and flow through the distal end of the graft measured again. Papaverine was administered and flow measured once more. Measured flows were consistent with those observed in previous studies, as were changes in flow induced by papaverine. Results indicate statistically significant diversion of blood through the fistulae, and a statistically significant increase in distal graft flow accompanying ligation of side branch fistulae. These data support the practice of routine side branch ligation during in situ bypass grafting.

Continuous infusion treatment with pentoxifylline in patients with severe peripheral vascular occlusive disease

The effect of continuous i.v. infusion of pentoxifylline, administering 1,200 mg/24 hours through 15 days, was studied in 22 patients (19 m, 3 f) with arteriographically confirmed extensive occlusion in the femoro-popliteal segment, associated with marked intermittent claudication and rest pain of varying severity. The following parameters were used for the verification of the therapeutic response: Flow resistance factor (RF), pressure indices at rest (RPI) and after exercise (PPI) and recovery time (RT) assessed by means of ultrasonic Doppler technique; muscle and skin blood flow at rest and after exercise using 99m Technetium Clearance Technique (TC); toe skin temperature (TST) by electric thermometer; painfree walking distance (WD) assessed on treadmill (horizontal, 4 km/h); rest pain (RP) was assessed by a 4-step-relief-scale. There was an overall good response to treatment, the studied parameters showing the following changes: RF improved in 12/17 patients (= 70%); RT decreased in 14/22 patients (= 63%) RPI and PPI showed no change; TC (muscle) increased after exercise in 17/22 patients (= 77%); TC (skin) increased after exercise in 20/22 patients (= 90%); WD increased on average by 80% (from 115 m to 206 m); TS increased in 16 limbs; RP showed an overall relief. The results of this study indicate that the continuous infusion of pentoxifylline is safe and effective in improving the condition of patients with severe peripheral vascular disease.

The femoral arterial flow velocity pattern in patients with atherosclerotic obstruction of the femoropopliteal segment. A study based on pulsed Doppler ultrasound flowmetry

The flow velocity pattern in the common femoral artery was analyzed in 107 limbs with femoropopliteal atherosclerotic obstruction and a normal aortoiliac segment. A pulsed wave Doppler ultrasound flowmeter was used. The highest (Va), the lowest (Vb) and the time average of the mean (V mean) velocities were obtained, and the pulsatility index (PI = Va-Vb/V mean) was calculated. In limbs with occluded (PI = 6.2) or greater than 50% stenotic (PI = 5.8) femoropopliteal segment, the flow velocity curve was slightly damped, with PI lower than in a control group (PI = 8.2). Neither stenosis of the profunda femoris artery nor the number of occluded leg arteries influenced the hemodynamic values in limbs with occluded femoropopliteal segment. Dampening of the femoral arterial flow velocity curve and reduced PI may indicate a stenotic (greater than 50%) or an occluded femoropopliteal segment. This flow pattern is also seen in aortoiliac atherosclerosis. In 76 limbs studied after femoropopliteal bypass, PI normalized when the bypass was patent, but was unchanged when the graft was occluded. Analysis of femoral arterial flow velocity pattern with calculation of PI may be useful in postoperative evaluation of femoropopliteal reconstruction.

Haemodynamic assessment of the femoropopliteal segment: comparison of pressure and Doppler methods using ROC curve analysis

Combined aorto-iliac and femoropopliteal vascular disease remains a problem in vascular surgery. Arteriography does not provide information on the relative contributions of the two lesions to the presenting symptoms. Aorto-iliac haemodynamics may reveal occult aorto-iliac disease but does not show whether combined proximal and distal reconstruction will be required to provide symptomatic relief. Haemodynamic assessment of both segments may help in this respect. A haemodynamic assessment of the femoropopliteal segment of 72 limbs in 38 patients is reported. The segmental pressure drop between a common femoral arterial cannula and a below-knee occlusion cuff is compared with a non-invasive Doppler method combining both transit time and damping factor. Comparison is made using receiver operating characteristic (ROC) curve analysis. The measurement of segmental pressure drop is more accurate than the Doppler method in detection of femoropopliteal stenoses of greater than 50 per cent of the luminal diameter (P less than 0.05).

Transcutaneous flow measurements in in-situ bypasses: an assessment of duplex scanning

Measurement of laminar flow using an ultrasound scanner was shown to have a high degree of correlation with quantified timed flows (r = 0.98, p less than or equal to .001). Sixty-one in-situ bypasses had flow assessed both proximally and distally. Mean fistula flow (proximal-distal flows) for time periods 1-8 weeks, 3 to 8, and 9+ months were 108, 85, and 16mls respectively. Distal bypass flow remained constant despite a significant decrease in fistula flow between the later time periods (p less than or equal to .001) (unpaired t-test). There was no evidence from the study that proximal flow through fistulas of varying resistances adversely affected the distal bypass flow.

Successful vein bypass in patients with an ischemic limb and a palpable popliteal pulse

Patients presenting with an ischemic foot who have a palpable popliteal pulse have not always been considered to be suitable candidates for arterial reconstruction. Since 1976, 32 distal bypasses were performed in 30 such patients, 77% of whom were diabetic. Proximal anastomoses were from the distal superficial femoral or popliteal artery. Autologous vein was used in all cases. There were six graft failures, all of which occurred within eight months. Three failures, which all occurred within the first month, required below-the-knee amputation. Using life-table analysis, the one- and three-year patency rates were both 79%. One- and three-year limb-salvage rates were 89% and 82%, respectively. We conclude that the results of distal vein graft reconstruction originating from the superficial femoral or popliteal artery are comparable with those of any group of patients with arterial occlusive disease of a lower extremity.

The preoperative angiogram as a predictor of peripheral vascular runoff

The preoperative angiogram is widely used as a means of assessing peripheral vascular runoff before bypass grafting, but the correlation between preoperative angiographic findings and actual measurements of peripheral vascular resistance has not been adequately examined. To test this correlation, we first devised a simple technique for measuring peripheral resistance and validated it in five dogs. Increases in peripheral resistance were artificially produced by temporarily occluding either the deep or superficial femoral artery or by intravenous administration of phenylephrine hydrochloride, a vasoconstrictor. In each instance, significant increases in resistance could be measured. We then used a similar technique to measure resistance in 23 patients undergoing peripheral bypass surgery. In addition, preoperative angiograms for these 23 patients were independently scored by four readers as 0, 1, 2, or 3 based on the number of patent vessels seen below the knee. Variations in scoring from reader to reader suggested that the present criteria for grading angiograms on this basis are unclear. Moreover, the correlation between angiographic score and measured resistance was poor for three of the four scorers (-0.21 to -0.29, p greater than 0.05). The angiographic scores of one reader, however, correlated reasonably well with the peripheral resistance measured at surgery (-0.59, p = 0.01). These findings demonstrate that current criteria for grading the preoperative angiogram are not sufficiently standardized to reliably predict runoff from a preoperative angiogram. However, these findings also suggest that it may be possible to identify angiographic findings that correlate well with changes in measured resistance.

Hemodynamic effects of intravenous PGE1 on patients with arterial occlusive disease of the leg

In 42 patients with arterial occlusive disease of the leg, the hemodynamic effects of prostaglandin E1 (PGE1) given intravenously were studied. Blood pressure of the leg and crest time of the pulse wave did not change significantly, while increases in blood flow at the calf and foot, amplitude of the pulse wave, velocity, and skin temperature at the foot and toes were significant. Skin temperature of the calf dropped significantly. The increase in blood flow, velocity, and skin temperature was significantly more dominant in the distal part of the leg than that in the proximal part. In separate observation of individuals, 12 of the 66 legs with arterial occlusive disease (18%) showed a decrease in skin temperature at the toes. The steal phenomenon was observed most frequently in limbs with rest pain, gangrene, or both.

The association between lowest palpable pulse and wound healing in below knee amputations

A retrospective study of 191 patients undergoing 203 Burgess type below knee amputations for end-stage peripheral vascular disease showed that the only clinical feature which associated significantly with wound healing was the lowest palpable pulse. The pulse level was noted preoperatively and was compared with the healing rates in the amputation stumps. When the femoral pulse was absent, 79% of below knee amputations failed. When the femoral pulse was palpable, only 29% wound breakdown occurred. When the popliteal or more distal pulses were palpable, only 10% failure was recorded.

Hemodynamics of human arterial stenoses

We assessed the hemodynamic and geometric changes in compliant, human arterial stenoses in response to manipulation of vascular tone, perfusion pressure and distal resistance. Coronary and popliteal arteries were harvested from human cadavers shortly after death. Following incubation for several hours to permit recovery of physiologic energy stores and ion gradients, the vessels were attached to a perfusion apparatus and perfusion pressure (PP), distal pressure (DP), and flow (F) were recorded as perfusion pressure and distal resistance (DR) were varied. The experiments were then repeated in the presence of a vasoconstrictor (100 mM KCl). Orthogonal arteriograms were performed at maximums of vasoconstriction and vasodilation. Stenotic resistance (SR) was calculated as (PP-DP)F. Minimum cross-sectional area was determined by computer assisted analysis of the arteriograms. Stenosed vessels with normal wall segments at the stenosis responded to vasoconstriction with a large stenotic resistance increase (111 +/- 15%; P less than 0.05) and a flow decrease averaging 39.3 +/- 6.2% (P less than 0.05). In addition, decreased perfusion pressure also increased stenotic resistance significantly (P less than 0.05). Stenotic resistance changes were of sufficient magnitude to be both statistically significant and clinically important. These results confirm the existence of dynamic arterial stenoses in humans and further support the assertion that dynamic stenotic severity changes elicited by manipulation of proximal and distal vascular tone and pressure are of sufficient magnitude to create acute ischemia. This information may apply to clinical situations in which compliant stenoses and acute ischemia coexist.

Collateral back pressure--is it a valid predictor of infrainguinal bypass graft patency?

While it is generally thought that collateral back pressure (CBP) is a reliable predictor of graft patency, this correlation has not yet been validated. We have used a new, simple technique to measure CBP without direct puncture of the recipient artery. After the distal anastomosis is completed, the graft is filled with saline and clamped proximally. A transducer connected needle is then inserted into the distal portion of the graft for CBP measurements (mm Hg). These were obtained in 84 grafts (43 femoropopliteals [FP] and 41 femorodistals [FD]). Outflow resistance (OR) measurements (mm Hg/ml/min) were also obtained in 70 (36 FP; 34 FD) of these grafts by a previously described technique. The mean CBP for FP and FD bypasses was 41 +/- 17 and 26 +/- 19 mm Hg, respectively (P less than 0.001). Although early graft patency (3 months) (13 occluded, 71 patent) did not correlate with angiographic findings of popliteal runoff or integrity of pedal arch, it did significantly relate to CBP. Mean CBP for occluded grafts was 22 +/- 17 mm Hg and for patent grafts it was 36 +/- 19 mm Hg (P less than 0.01). Similarly, mean OR was significantly related to patency, 1.29 +/- 0.23 mm Hg/ml/min for occluded grafts and 0.36 +/- 0.23 mm Hg/ml/min for patent grafts (P less than 0.0001). Moreover, only OR was a significant predictor of infrapopliteal graft patency (P less than 0.01). OR was found to be a better predictor of graft patency than CBP by stepwise logistic regression analysis (P less than 0.0001). We conclude that CBP is a more reliable predictor of graft outcome than angiographic criteria.(ABSTRACT TRUNCATED AT 250 WORDS)

The haemodynamic effects of percutaneous transluminal angioplasty

The aim of the study was to measure the haemodynamic effect of percutaneous transluminal angioplasty (PTA). Twenty-one consecutive patients with unilateral stenosis of the iliac (n = 13) or femoropopliteal arteries (n = 8) causing intermittent claudication were studied with ankle and brachial systolic pressure measurements before and after PTA and at six monthly intervals. In 15 patients, the pressures were measured not only at rest, but after exercise on a standard treadmill. There were six technical failures. All of the remaining patients were improved clinically and objectively. The resting pressure index increased from mean (+/- ISD) of 0.65 +/- 0.22 to 0.88 +/- 0.17 and the postexercise index from 0.43 +/- 0.21 to 0.82 +/- 0.22. The preoperative claudication distance was improved from 83 m +/- 31 to 252 m +/- 104 and the recovery time from 6.3 mins +/- 5.7 to 1.5 mins +/- 2.3. During the follow up period of six weeks to 2 1/2 years, the initial improvement was maintained and there were no failures clinically or on further Doppler examination. The results suggest that for patient with a single significant stenosis, PTA is an effective alternative method of treating claudication.

Value of Doppler multi-level segmental pressure index in the diagnosis and hemodynamic characterization of totally occlusive aorto-iliac-femoro-popliteal lesions

Four-level lower limb Doppler S.P.I. (upper thigh; above knee; below knee; above ankle) were evaluated in 275 limbs, 110 of which showed totally occlusive lesions at one or more levels of the aorto-iliac-femoro-popliteal axis on angiographic examination, 65 showed stenosis less than 50% (sclerotic controls) and 100 did not undergo arteriographic examination since they apparently had no lesions (healthy controls). Analysis of the results-carried out using the Student's t statistical method-showed a drop in the S.P.I. close to or over 0.30 between two adjacent levels and was indicative of the presence of an occlusion in the intermediate area. This method therefore allowed the presence and the position of an isolated lesion to be detected. In the case of multiple lesions in series, the proximal one is detected with certainty, whereas the more distal ones can be recognized but not their exact position and extension. Multiple lesions in series are more hemodynamically significant than isolated ones, and proximal lesions more than distal ones.

Evaluation of graft patency utilizing the ankle-brachial pressure index and ankle pulse volume recording amplitude

To determine femoropopliteal graft patency, the ankle-brachial pulse index and the ankle pulse volume recording amplitude were measured. Fourteen healthy volunteer subjects were tested on two occasions over 24 hours (ankle-brachial pressure index 1.14+:-0.16, change 0.03+:-0.05; ankle pulse volume recording amplitude 25+:-7 mm, change 5+:-4 mm). In the second control group, hemodynamic function in the unoperated limb was studied before and after surgery in 40 patients undergoing infrainguinal bypass on the contralateral side (preoperative ankle-brachial pressure index 0.66+:-0.3, change 0.02+:-0.12; preoperative ankle pulse volume recording amplitude 8+:-7 mm, change 1+:-3 mm). After 119 patent femoropopliteal bypasses ankle-brachial pressure index and ankle pulse volume recording amplitude increased by 0.41+:-0.26 and 11+:8 mm, respectively.

Interpretation of Doppler segmental pressures in peripheral vascular occlusive disease

Measurement of Doppler segmental arterial pressures in the lower extremity using narrow pneumatic cuffs has become a standard noninvasive diagnostic technique. Correlation between arteriographic and noninvasive studies was available for 345 aortoiliac segments and 326 femoropopliteal segments. If stenoses of 50% or greater and occlusions were considered hemodynamically significant, the sensitivity to aortoiliac disease was 97%, but only 67% to femoropopliteal disease. The specificity for hemodynamically insignificant disease was 50% and 68%, respectively. Accuracy was influenced by the presence of associated aortoiliac or femoropopliteal disease. The sensitivity to hemodynamically significant femoropopliteal disease was 55% if there was associated aortoiliac disease, and 89% in its absence. In the presence of significant femoropopliteal disease, specificity for the absence of aortoiliac disease decreased from 70% to 41%.

Comparative study of four methods for quantifying Doppler ultrasound waveforms from the femoral artery

Currently, there is no agreement as to the best method for quantifying Doppler ultrasound recordings from peripheral arteries in order to detect occlusive disease. The four methods assessed in this study are: the pulsatility index, height-width index, path length index, and a Laplace transform function index. Recordings of the Doppler ultrasound spectral waveforms from the common femoral artery of 232 limbs were digitized to obtain the maximum velocity waveforms. This data was analyzed and the various indices were computed and then compared with the arteriographic grades. The effect of distal disease was also examined. The diagnostic accuracy of each index was determined from receiver operating characteristics curves. We concluded that all four indices were capable of detecting significant aortoiliac disease with approximately equal diagnostic accuracy of 90-95% but that pulsatility index had the advantages of simplicity and ease of calculation.

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.

Predicting success in limb salvage

While success in revascularization procedures for severe arterial insufficiency--limb salvage--demands a technically correct operation, the adequacy of the outflow system is equally important. An outflow index (phi), the percentage drop in femoral artery pressure following an intra-arterial injection of papaverine, was developed. The predictive value of this index was demonstrated in a prospective study of 44 limbs in which an aortoiliac procedure with profundoplasty was done for multilevel disease. In the operations considered completely successful (n = 27), the mean value of phi was 37 +/- 8 per cent; this was significantly greater (P less than 0.001) than the mean value of 16 +/- 9 per cent found for those operations (n = 17) deemed to have been unsuccessful on the basis of rigorous postoperative criteria. This finding not only proves the efficacy of the index, but emphasizes the importance of an outflow system with the ability to accept more blood.

Differential diagnosis of arterial disease of the lower limb using Doppler ultrasound

Doppler arterial waveforms from the femoral and ankle arteries of 55 normal control subjects and 76 arteriopaths were analysed for Laplace transform coefficients, delta and omega omicron, and pulsatility index (PI). At the femoral artery delta was superior to PI in accurately detecting mild and moderate aortoiliac stenosis, as assessed from arteriograms. In the femoropopliteal segment, the ratio of omega omicron from femoral to ankle level compared favourably with PI damping factor in the detection of occlusive disease. The Laplace transform system provides a helpful diagnostic method in lower limb arterial disease.

An objective feature extraction technique applied to the Doppler waveforms from the groin: a prospective study

A group of 80 patients presenting with lower limb ischaemia were classified according to their arteriographic findings. The maximum frequency envelope from the Doppler waveforms obtained from the common femoral artery were retrospectively analysed using a mathematical feature extraction technique, principal component analysis (PCA). Two of the three coefficients uniquely describing each waveform were plotted and classified according to their arteriographic groupings. The best separating planes were then defined. Twenty-eight new patients were subsequently prospectively assessed using the principal components and separating planes defined in the previous study. The results were compared with the arteriographic findings and showed that PCA represents a significant improvement in diagnostic accuracy when compared with other techniques.