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Pressures were measured in the carotid arteries of 61 patients proximal and distal to atherosclerotic plaques which were carefully studied by angiography and anatomical dissection. (1) An atherosclerotic plaque causing a constriction of less than 47% luminal diameter leaving a lumen greater than 3.0 mm in diameter never caused pressure drops of greater than 10 mm Hg. Stenoses of greater than 63% luminal diameter leaving lumens less than 1.0 mm in diameter always caused pressure drops. (2) Atherosclerotic plaques producing defects which narrowed the lumen fell into a distinct pattern: (a) Type 1 lesions—This basic lesion filled the bulb of the internal carotid artery near its origin, causing a 1 to 2 cm smooth elliptical encroachment on the lumen. (b) Type 2 lesions—Short localized areas of thickening in addition to the basic lesion caused bar-like defects of the lumen at the origin of the internal carotid artery or near the distal end of the lesion. (c) Type 3 lesions—Multiple bar-like defects were sometimes seen. (d) Type 4 lesions—The areas of increased thickening of the lesion were sometimes quite narrow, producing diaphragm-like defects on the lumen. Although theoretically these various types of stenoses should produce different hemodynamic changes, insufficient numbers of observations were made to corroborate these presumptions. (3) Angiograms in general mimicked the gross appearance of the plaques and predicted the actual degree of stenosis produced but did not identify many diaphragm defects, ulcerations, or small thrombi.

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Duplex-derived velocity measurements were used to assess the hemodynamics of 64 femoropopliteal arterial sites in 59 patients after angiographically successful percutaneous transluminal balloon angioplasty. With use of angiography as the gold standard, percutaneous transluminal balloon angioplasty was judged to be successful if (1) evidence existed of a "split" caused by intimal dissection and splitting of atherosclerotic plaque; and (2) no significant diameter-reducing residual stenosis was observed at the percutaneous transluminal balloon angioplasty site. At 1 month, 55 limbs (86%) were hemodynamically and clinically improved by SVS/ISCVS clinical criteria for chronic limb ischemia. Of the 55 percutaneous transluminal balloon angioplasty sites, duplex scanning had identified 40 (63%) sites with a less than 50% diameter-reducing stenosis and 15 (27%) sites with a greater than 50% diameter-reducing stenosis within a week after percutaneous transluminal balloon angioplasty. Independent review of the 55 angiograms taken after percutaneous transluminal balloon angioplasty identified 39 sites (71%) with a split and 16 sites (29%) without. By life-table analysis, a greater than 50% diameter-reducing stenosis predicted a worse clinical outcome (15% at 1 year) compared with the presence of a less than 50% diameter-reducing stenosis (84% at 1 year) (p less than 0.001; log rank test). The presence or absence of an angiographic split was not a predictive factor of percutaneous transluminal balloon angioplasty outcome (split, 61% at 1 year; no split, 62% at 1 year) (p = 0.832; log rank test). The detection of a functional residual stenosis by duplex scanning did not correlate with angiographic appearance, but was predictive of clinical failure.(ABSTRACT TRUNCATED AT 250 WORDS)

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