White-Flores Sa

Six-year prospective multicenter randomized comparison of autologous saphenous vein and expanded polytetrafluoroethylene grafts in infrainguinal arterial reconstructions

Autologous saphenous vein (ASV) and polytetrafluoroethylene (PTFE) grafts were compared in 845 infrainguinal bypass operations, 485 to the popliteal artery and 360 to infrapopliteal arteries. Life-table primary patency rates for randomized PTFE grafts to the popliteal artery paralleled those for randomized ASV grafts to the same level for 2 years and then became significantly different (4-year patency rate of 68% +/- 8% [SE] for ASV vs. 47% +/- 9% for PTFE, p less than 0.025). Four-year patency differences for randomized above-knee grafts were not statistically significant (61% +/- 12% for ASV vs. 38% +/- 13% for PTFE, p greater than 0.25) but were for randomized below-knee grafts (76% +/- 9% for ASV vs. 54% +/- 11% for PTFE, p less than 0.05). Four-year limb salvage rates after bypasses to the popliteal artery to control critical ischemia did not differ for the two types of randomized grafts (75% +/- 10% for ASV vs. 70% +/- 10% for PTFE, p greater than 0.25). Although primary patency rates for randomized and obligatory PTFE grafts to the popliteal artery were significantly different (p less than 0.025), 4-year limb salvage rates were not (70% +/- 10% vs. 68% +/- 20%, p greater than 0.25). Primary patency rates at 4 years for infrapopliteal bypasses with randomized ASV were significantly better than those with randomized PTFE (49% +/- 10% vs. 12% +/- 7%, p less than 0.001). Limb salvage rates at 3 1/2 years for infrapopliteal bypasses with both randomized grafts (57% +/- 10% for ASV and 61% +/- 10% for PTFE) were better than those for obligatory infrapopliteal PTFE grafts (38% +/- 11%, p less than 0.01). These results fail to support the routine preferential use of PTFE grafts for either femoropopliteal or more distal bypasses. However, this graft may be used preferentially in selected poor-risk patients for femoropopliteal bypasses, particularly those that do not cross the knee. Although every effort should be made to use ASV for infrapopliteal bypasses, a PTFE distal bypass is a better option than a primary major amputation.

Tibiotibial vein bypass grafts: A new operation for limb salvage

Tibiotibial bypasses were performed with short (8 to 33 cm) segments of reversed autologous vein in 14 patients who did not have longer segments of usable vein. All patients faced imminent amputation unless they had an effective revascularization. Two patients died, one within 1 month of operation. One patient required below-knee amputation despite a patent bypass. Eleven patients (79%) have a patent bypass and a functional limb 6 to 50 months after operation. These good patency results even with several grafts inserted into isolated segments of tibial arteries, some with incomplete plantar arches, suggest that these short vein grafts may be superior to other vein grafts. Tibiotibial bypasses may improve limb salvage results in otherwise difficult circumstances.

Components of outflow resistance and their correlation with graft patency in lower extremity arterial reconstructions.

We have used a simple reproducible method to measure total outflow resistance (OR) and its proximal and distal components in 101 bypasses (46 femoropopliteal [FP] and 55 femorodistal [FD]). All bypasses with a distal OR greater than 1.2 mm Hg/ml/min failed within 3 months and all with distal OR less than 1.2 mm Hg/ml/min remained patent for at least 3 months. To evaluate the contribution of vasospasm to OR and its role in graft failure, 60 bypasses (29 FP, 31 FD) had OR measurements before and after local infusion of papaverine hydrochloride (60 mg). Within 3 months, nine grafts (all FD) occluded and 51 remained patent. All nine failures had distal OR greater than 1.2 mm Hg/ml/min before papaverine infusion. After infusion, the mean percentage decrease in both total and distal OR for all grafts was 30% and 31%, respectively. However, there was no significant difference between these papaverine-induced decreases in OR and 3-month graft failure or success. Moreover, in three bypasses, even though papaverine lowered the distal OR from greater than 1.2 to less than 1.2 mm Hg/ml/min, early occlusion occurred. In six grafts (1 FP, 5 FD) when total and distal OR before and after papaverine was greater than 1.2 mm Hg/ml/min, the graft was extended to a second distal artery as a sequential bypass. These six grafts have remained patent over 3 months. Thus measurement of OR and particularly distal OR is a most accurate predictor of early graft success or failure. Pharmacologic manipulation does not enhance the predictive value of the OR measurement. OR measurements also help to select those FD bypass cases in which extension to a second distal artery as a sequential bypass improves patency.

Intraoperative outflow resistance as a predictor of late patency of femoropopliteal and infrapopliteal arterial bypasses

To evaluate the efficacy of intraoperative outflow resistance (OR) measurements in predicting late graft patency rates (PR) for femoropopliteal (FP) and femoroinfrapopliteal (FD) bypasses, we have reviewed 134 such cases performed during the past 3 years at our institution. Of these, 64 bypasses were FP (13 autogenous saphenous vein [ASV] and 51 polytetrafluoroethylene [PTFE]) and 70 were FD (43 ASV and 27 PTFE). Total and distal OR measurements (measured in millimeters of mercury per milliliter per minute) were divided into four groups each for all infrainguinal bypasses combined and for FP and FD bypasses separately. The relationship of PR to total and distal OR measurements were analyzed according to the product limit method. Overall 1- and 2-year PRs were 64% and 56%, respectively. For FP bypasses the same PRs were 78% and 67% whereas for FD bypasses, they were 52% and 45%, respectively. The 1-year PRs for FP and FD bypasses within each respective OR group were analyzed. For FP bypasses in the lowest to the highest total OR groups, the 1-year PRs were 86%, 75%, 78%, and 62% (NS), and for FD bypasses they were 72%, 89%, 23%, and 22% (p less than 0.001). Similar trends were observed when distal OR measurements were analyzed. For infrainguinal PTFE bypasses, both total and distal OR measurements were significant predictors of patency, whereas for those with ASV only distal OR measurements were predictive. These data reaffirm our early experience with OR measurements. Although a trend for predicting graft patency was noted for FP bypasses, OR measurements were highly predictive only for FD bypasses.

Quantitative assessment of outflow resistance in lower extremity arterial reconstructions

Graft patency is thought to correlate with resistance in the runoff bed or outflow resistance. However, accurate measurement of this parameter has been difficult. A simple and reproducible method for direct measurement of outflow resistance following completion of the distal anastomosis of a bypass graft has been developed. This method employs injection of a fixed amount of normal saline through the proximal end of the graft and measurement of the resulting integrated pressure increment by an analog computer. Division of this pressure integral by the volume injected is a measure of the outflow resistance expressed in resistance units (mm Hg/ml/min). The median outflow resistance in 31 femoropopliteal bypasses was 0.29 units with a range of 0.08-1.38 units. The median outflow resistance in 33 femorodistal bypasses was 0.7 units with a range of 0.18-2.34 units. All bypasses with an outflow resistance of 1.1 units or less remained patent for 3 months. There were 51 grafts in this group (30 femoropopliteal; 21 femorodistal) and their outflow resistance ranged from 0.08 to 1.1 units. All bypasses with an outflow resistance of 1.2 units or higher thrombosed within the first postoperative month. There were 13 grafts in this group (1 femoropopliteal; 12 femorodistal) and their outflow resistance ranged from 1.2 to 2.38 units. Eight of the 13 grafts that failed originally were subjected to thrombectomy, which was uniformly unsuccessful. Although this method does not yet allow bypass surgery to be denied to any patient, it does define a group of patients in whom thrombectomy will not be effective and should not be attempted.(ABSTRACT TRUNCATED AT 250 WORDS)

System for widespread application of microcomputers to vascular surgery

The application of microcomputers to vascular surgery has been limited because of the lack of software that allows collection and effective evaluation of a large amount of patient-related data. We have developed a microcomputer-based data handling system for evaluating vascular patients that is inexpensive (

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

6000 to

Diagnosis and management of failing lower extremity arterial reconstructions prior to graft occlusion

8000), easy to use, and flexible. Its simplicity for nonprogrammers is achieved through a natural interface with menu-driven operations and descriptive English language messages. With this system eight data entry forms were designed, and data on more than 1000 patients treated for peripheral vascular disease over the last 7 years were entered into the computer by clerical personnel with minimal training. A query language report generator allowed us to obtain reports of results in simple English on any set of selection criteria with all relevant statistical functions, including cumulative life-table patency rates. This system has the following advantages: rapid evaluation of data from several retrospective and prospective studies, such as comparison of graft material, effect of local and systemic risk factors, cost of limb-salvage surgery, and correlation of noninvasive laboratory tests with other parameters; more accurate patient follow-up, with elimination of many of the pitfalls involved in observing large groups of patients frequently; and quantitation of individual surgeon or service results for quality control and self-review, which guide the vascular surgeon to modify treatment protocols, patient selection, and/or surgical techniques. Wider use of this system for data collection and evaluation will help to standardize data reporting and thus allow accurate comparison of data from different centers.

Comparison of axillounifemoral and axillobifemoral bypass operations

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)