Variations in interpretation of arterial stenosis.

A survey containing schematic diagrams of differing shapes and sizes of arterial plaque was mailed to 200 vascular surgeons with 62 responses. The interpretations of these images differed widely, reflecting a disagreement in basic principles of assigning values to the residual and normal lumen size of arteries with stenotic plaque. Predominant opinion was split between the use of area versus minimum diameter and in considering the effects of taper and branching. A plea is made for discussion and adoption of a consensus so that more meaningful conclusions can be drawn from future data.

Real-time duplex ultrasound mapping of the greater saphenous vein before in situ infrainguinal revascularization.

From November 1983 through September 1985, 102 greater saphenous veins (GSVs) were assessed and mapped by means of real-time duplex ultrasonic scanning before in situ infrainguinal revascularization. Each GSV was also visually assessed at operation. Eighty-five GSVs were successfully used for infrainguinal revascularization; duplex scanning correctly identified 82 of these GSVs as being acceptable for use in in situ bypass. Seventeen GSVs were unacceptable for in situ bypass; duplex scanning correctly identified 11 of these as being unacceptable. Duplex scanning provides anatomic information about the GSV, including size, patency, course, varicosities, double segments, and tributaries. This information permits the surgeon to perform infrainguinal revascularization expeditiously.

Sequential femoro-popliteal-tibial bypass grafting: operative technique and results.

Sequential femoro-popliteal-tibial saphenous vein grafts were constructed in 25 patients for limb salvage. Angiographically, these patients had an isolated popliteal artery segment and at least one distal tibial or peroneal artery patent. In each case, two distal anastomoses were made: one side-to-side to the isolated popliteal segment and the other end-to-side to a tibial or peroneal artery. Twenty-three of 25 grafts were successful; there was an immediate increase in ankle/brachial pressure index and limb salvage. Patency rates calculated by life table analysis were 90.2% at six months, 83.8% at one year, and a stable interval patency thereafter. For comparison, 65 standard femoro-tibial or peroneal vein grafts performed during the same time interval by the same surgeons were analyzed. Each graft had one distal anastomosis to a tibial or peroneal artery. Graft patency was 75% at six months, 72.6% at one year, 54.5% at two years, and 49.7% at three years. The superior patency rate of the sequential grafts was statistically significant (p less than .03). We conclude that the sequential vein graft technique may result in more complete extremity revascularization and increased graft flow, thereby improving patency rates. In selected patients with an isolated popliteal segment and a patent distal tibial or peroneal artery, the sequential graft technique should be considered.

Extended study of aneurysm formation in umbilical vein grafts.

The rate of aneurysm formation in umbilical vein grafts has been reported to lie between 1% and 8%. However, in these reported series the number of grafts with aneurysms was related to the number of grafts inserted. When the denominator is changed to patent grafts at a given time period, the incidence changes drastically. In this study, duplex scanning was used to detect aneurysms in patent grafts. Four types of aneurysms--localized fusiform, localized eccentric, diffuse, and anastomotic--were recognized. Excluding anastomotic aneurysms, 33% of the grafts patent at 3 years were aneurysmal; in those patent at 4 years, 45% were aneurysmal; and in those patent at 5 or more years, 65% were aneurysmal. On grounds of theoretical considerations, it is believed that duplex scanning is more reliable than either clinical examination or arteriographic study for detecting these aneurysms. There is now evidence that the supporting Dacron mesh is too weak and must be strengthened. Despite aneurysm formation, the patency rate in our series has remained second only to saphenous vein grafts, as previously reported.

Pulsatile flow simulator for comparison of cardiac output measurements by electromagnetic flow meter and thermodilution.

This study examined a pulsatile flow simulator for the purpose of evaluating two measurement devices, an extracorporeal flow probe with an electromagnetic flow meter and several thermodilution catheters. We measured the performance of these devices in a range of low to high flows. Using either saline or blood as a perfusate, we obtained different results with these fluids (p less than 0.001). Each catheter behaved in a linear manner, although variation occurred among the catheters with both saline (minimum slope 1.090, maximum slope 1.190) and blood (minimum slope 1.107, maximum slope 1.154). An increase in rate and stroke volumes of the simulator did not demonstrate an identifiable trend in error. The thermodilution catheters were most accurate at 5.0 L/min irrespective of rate, stroke volume, or perfusate used. In contrast, the electromagnetic flow meter accurately represented flows across the wide range of outputs examined (2.4 to 10.7 L/min). (Slope with saline 1.091, slope with blood 1.080) Throughout the range of flow, the flow meter gave a calibration line 5% higher with blood than with saline. The results indicate that accurate measurement of pulsatile blood flow can be achieved in vitro with an electromagnetic flow meter using saline as a perfusate, provided a correction factor is determined and applied to convert values for saline to accurate values for blood.