Tobacco. Its impact on vascular disease.

The role of smoking in vascular disease is multifactorial and complex. Research continues to further elucidate the mechanisms involved and advance treatment options. What remains clear throughout is that smoking cessation has multiple health benefits. In a recent public health projection study of mortality and disability by cause, tobacco use was marked as the potentially largest health problem to be expected in the year 2020. Although smoking cessation is not simple, in the years spanning 1993 to September 1997, 1720 articles were published under the key words "smoking cessation," reflecting the difficulty of this endeavor and lack of a satisfying answer to this health problem. Nonetheless, approaches to patient smoking cessation should be attempted by all physicians. A protocol for physicians to assist patients with smoking cessation from the National Cancer Institute can serve as a general guide (Fig. 3). Some of the programs available to assist patients in smoking cessation are listed in Table 7.

Determination of carotid plaque risk by ultrasonic tissue characterization.

This in vitro study investigated the ability of ultrasonic tissue characterization (UTC) to discriminate between plaques from asymptomatic and symptomatic patients and to compare UTC findings with quantitative measurements of plaque morphology. A total of 34 plaque specimens removed at carotid endarterectomy were scanned transversely at intervals of 1 mm, and compared to tissue cross-sections examined by optical microscopy employing computer-assisted planimetry. UTC was performed by spectral analysis of backscattered radiofrequency signals. The slope, intercept and total power parameters of the spectrum were evaluated. Discriminant analysis was used to compare the ability of the UTC spectral parameters and morphological constituents to correctly classify plaques according to their symptom group membership. UTC correctly classified 88.2% of the plaques. Thrombus was present in 93.9% of the plaques, and there was little difference in the morphological constituents of plaques from asymptomatic and symptomatic patients. Morphological constituents correctly classified 60.7% of the plaques. We conclude, in this preliminary study, that UTC can discriminate between carotid plaques from asymptomatic and symptomatic patients with moderate accuracy, despite a similarity in their morphological composition. UTC discrimination is not related to differences in the type or amount of morphological constituents in the plaques.

Occluded infrainguinal grafts: when to choose lytic therapy versus a new bypass graft.

BACKGROUND: The published results of thrombolysis for occluded bypass grafts, including a prospective multicenter trial, have been disappointing, prompting many investigators to proceed directly to a new bypass rather than attempt graft salvage. Our series of 61 occluded grafts treated with lytic therapy, however, identified a subgroup that justified attempted graft salvage. METHOD: The grafts consisted of saphenous vein 59% (36/61), other vein (arm or composite vein) 21% (13/61), and polytetrafluoroethylene (PTFE) 29% (13/61). The data analysis was designed to identify the graft subgroup that would benefit from lytic therapy by using cumulative survival analysis techniques with the Wilcoxon (Gehan) test for univariate analysis and Cox proportional hazards model for multivariate analysis. Specific variables examined by univariate analysis were graft age (defined as the interval from initial bypass to graft lysis), graft material, graft type (femoropopliteal versus femorotibial), diabetes, symptoms (claudication versus salvage) and duration of occlusion prior to lysis. RESULTS: Complete lysis was achieved in 72% (44/61) of the grafts, and 86% (38/44) had an underlying stenosis that was treated by percutaneous balloon angioplasty (28/38) or surgery (7/38). Three stenotic outflow lesions were not treated. Cumulative 5-year patency for all 61 grafts was 23% +/- 0.075 (SE). Only graft age < 10 versus > 10 months was significant (P < 0.004) by univariate analysis, and it was also the only significant variable found by multivariate analysis; it indicated a 1.58 increase in relative risk of occlusion for the younger grafts. The combination of a saphenous vein graft that was also > 10 months old resulted in a 45% 5-year patency, compared to 21% for < 10-month-old saphenous vein grafts (P < 0.008). A review of 161 bypass grafts performed at our institution over the past 10 years revealed a 52% 5-year secondary patency in previously bypassed limbs, which varied with graft material (67% saphenous, 50% alternative vein, 31% prosthetic). Lysed graft patency was comparable to that of a second bypass using other veins or PTFE conduit. CONCLUSIONS: In the absence of an intact saphenous vein for a second bypass, thrombolytic therapy is an alternative to surgery.

Popliteal artery aneurysms: current management and outcome.

PURPOSE: Thrombosis of popliteal artery aneurysms can produce limb-threatening ischemia. In this setting we have found preoperative thrombolytic therapy to be beneficial. METHODS: Thirty-three patients with 54 popliteal artery aneurysms were studied (mean follow-up 62 months). Twenty-one patients (62%) had bilateral popliteal artery aneurysms, and 20 patients (61%) had extrapopliteal arterial aneurysms. Thirty-three (61%) aneurysms had symptoms of compression or ischemia, and 21 (39%) aneurysms had thrombosis. A trend toward thrombosis for larger aneurysms was noted (p < 0.068). RESULTS: Forty-five aneurysms were treated with bypass grafting. Five-year graft patency and limb salvage rates were 71% and 90%, respectively. Factors favoring graft patency and limb salvage included presence of two- or three-vessel runoff compared with patients with single- or no-vessel runoff (p < 0.025 graft patency; p < 0.003 limb salvage) and presence of a patent aneurysm (p < 0.005 graft patency and limb salvage). Seven patients diagnosed with thrombosis of their aneurysm and all runoff vessels were treated with preoperative thrombolytic therapy. Complete clearing of thrombus from these arteries was achieved in six of these patients (and from two of these runoff vessels in the remaining patient). These patients had better graft patency (p < 0.005) and limb salvage (p < 0.01) than comparable patients treated with emergency operations. Six amputations were performed in the follow-up interval, none of which were performed in patients having undergone thrombolytic therapy. CONCLUSIONS: It is concluded that popliteal aneurysms are managed best by elective repair of patent aneurysms with good runoff. In that difficult situation of the thrombosed popliteal artery aneurysm associated with acute leg ischemia, thrombolytic therapy safely and effectively provides patients with a more favorable alternative than emergency surgery.

Blinded-reader comparison of magnetic resonance angiography and duplex ultrasonography for carotid artery bifurcation stenosis.

BACKGROUND AND PURPOSE: We compared two-dimensional time-of-flight magnetic resonance angiography (MRA) and duplex ultrasonography with arteriography for the detection of 70% to 99% stenoses at the carotid artery bifurcation (ie, surgical disease according to findings of the North American Carotid Endarterectomy Trial). METHODS: Three blinded readers independently measured stenoses on MRA in 73 vessels from 38 patients. Duplex ultrasonography was available in 66 vessels from 35 of these patients, and blinded reading was performed by one reader. Comparison was made to arteriography. RESULTS: Magnetic resonance angiography demonstrated a sensitivity of 92.4%, specificity of 74.5%, and negative predictive value of 95.8% for 70% to 99% stenoses. Interobserver agreement was high (kappa = 0.91). Absence of signal at stenoses with evidence of distal flow usually, but not always, corresponded to surgical disease. Duplex ultrasonography demonstrated a sensitivity of 81.0%, specificity of 82.2%, and negative predictive value of 90.2% for surgical disease. There was no significant difference between MRA and duplex ultrasonography for the sensitivity or specificity in detecting 70% to 99% stenoses (P > .1, exact form of the McNemar test). MRA had no false positives or false negatives for complete occlusions of the carotid artery, whereas duplex ultrasonography missed one occlusion and falsely called two patent vessels occluded. In seven cases, both MRA and duplex ultrasonography overestimated stenoses to miscategorize them as surgical disease. CONCLUSIONS: Although the sensitivity and specificity of MRA and duplex ultrasonography are not significantly different for distinguishing surgical and nonsurgical degrees of stenosis at the carotid bifurcation, MRA has some advantages that may make it the screening test of choice. Concordant MRA and duplex ultrasonography for surgical disease does not necessarily obviate the need for catheter arteriography.

Infrageniculate bypass graft entrapment.

When failure of vein grafts is due to technical error it is usually observed in the early postoperative period. In this review we describe late failure of five bypass grafts as a result of entrapment of the vein graft caused by an improperly placed tunnel from the femoral to the popliteal artery. Vein graft entrapment may either produce no symptoms or eventually lead to limb ischemia. Pulses and pressures that vary with flexion and extension maneuvers should alert the clinician to the possibility of an entrapment syndrome. The characteristic arteriographic findings observed in these patients include an aberrant course of the vein graft outside the anatomic course of the popliteal artery and position-dependent compression of the graft. The ability of magnetic resonance angiography to demonstrate the arteriographic appearance of the graft as well as the precise location of the compression and to identify structures involved in the entrapment, make it a valuable noninvasive tool in the preoperative assessment of these patients. Treatment options include division of the gastrocnemius muscle, division of the vein graft, or replacement of the vein graft. Familiarity with vein graft entrapment should facilitate its recognition. Careful placement of bypass grafts along the anatomic course of the popliteal artery within the popliteal space will prevent this complication.

Magnetic resonance angiography of peripheral runoff vessels.

Recent improvements in magnetic resonance imaging techniques have made magnetic resonance angiography (MRA) a very useful adjunct to invasive angiography. Fifty-five limbs in 51 patients with occlusive peripheral vascular disease were studied with both MRA and contrast arteriography. The magnetic resonance and contrast arteriograms were read by radiologists and surgeons and separate interventional plans were based on each study. The MRA findings differed significantly from those of conventional arteriography in 26 limbs (48%). In every case MRA visualized all of the same vessels and hemodynamic stenoses seen on the contrast arteriogram. In 48% of the cases, however, MRA revealed additional findings. Thus the discrepancies in the two studies were always the result of the failure of the arteriogram to reveal all of the patent vessels seen on MRA. The additional information provided by MRA resulted in alteration of the interventional plan in 11 cases (22%). In nine cases (18%) target vessels suitable for use in a limb-salvage procedure were identified by MRA, although they had been missed by conventional arteriography. In all of these cases, intraoperative arteriograms confirmed the suitability of these vessels for use in technically successful bypass procedures. In two cases (4%) additional information provided by MRA identified a target runoff vessel for bypass grafting that proved to be a better alternative than the one that would have been chosen on the basis of contrast arteriography.(ABSTRACT TRUNCATED AT 250 WORDS)

Reversed vein graft stenosis: early diagnosis and management.

Conscientious surveillance of intrainguinal bypass grafts is mandatory to detect vein graft stenoses, which, if uncorrected, can lead to graft occlusion. It is now widely accepted that noninvasive vascular laboratory studies are the best way to detect these lesions. However, controversy still exists over treatment, specifically whether balloon angioplasty is an acceptable substitute for surgery (patch angioplasty or short jump grafts) in the treatment of these lesions. We have always favored balloon angioplasty as primary treatment and have summarized our experience with treating 72 stenotic reversed femoropopliteal and femorotibial vein grafts, which represent 12% of 521 bypass grafts performed at our institution. Prosthetic and in situ grafts are specifically excluded from this report, as well as occluded grafts, found to have stenotic lesions after lytic therapy. The most common stenotic lesion occurred within 4 cm of the proximal anastomosis (29/72 = 40%). The other sites were near the distal anastomosis (7/72 = 10%), and in the middle of the graft (15/72 = 12%). Eighty-one percent (58/72) of the lesions were treated initially by balloon angioplasty with a 31% recurrence. Twenty-nine percent of the 14 grafts treated surgically by vein patch angioplasty or short jump grafts experienced recurrence. Overall 61% (44/72) of the stenotic grafts were treated by balloon angioplasty alone. The 5-year life-table assisted primary patency after correction of the stenotic lesion was 61%. The patency of the grafts from the time of initial bypass surgery, however, was 80%. Location of the stenosis within the graft was a major determinant of patency. Lesions in the proximal graft, proximal anastomosis, and distal graft taken as a group had significantly better patency than the midgraft and distal anastomotic lesions (5-year patency, 65% vs 48%, p less than 0.001 log rank test). We continue to recommend balloon angioplasty as primary therapy for vein graft stenosis except for those occurring in the midgraft and distal anastomosis. Fortunately, this group accounts for only 36% of lesions seen with reversed veins. Recurrent stenosis after balloon angioplasty should be repaired surgically.

Thoracoabdominal aneurysm resection after previous infrarenal abdominal aortic aneurysmectomy.

Thoracoabdominal aneurysms in 51 patients were repaired over 5 years ending in February 1991. Fourteen (27%, 14 of 51) patients had a prior infrarenal aneurysm resection (PRA); their data are analyzed separately. The average age of patients who had undergone PRA was 67 years (range: 56 to 86 years). The mean aneurysm diameter was 8.6 cm (range: 5 to 12 cm), and the mean time interval between initial aneurysm surgery and subsequent resection of the thoracoabdominal aneurysm was 8.5 years (range: 2 to 17 years). Three patients in the PRA group were operated on emergently, two because of clinical evidence of rupture; the other patients underwent elective repair. Early mortality (30 days) in the PRA group was significantly related to age (72 years or older versus younger than 72 years: 75% versus 10%, p = 0.04), proximal extent of aneurysm (above diaphragm versus below diaphragm: 50% versus 0%, p = 0.05), ruptured aneurysm (ruptured versus nonruptured: 100% versus 16%, p = 0.06), and a cardiac history of myocardial infarction (57% versus 0%, p = 0.03), congestive heart failure (66% versus 0%, p = 0.01), or arrhythmia (80% versus 0%, p = 0.005). Similar results were seen with the entire group of patients with thoracoabdominal aneurysms except that the proximal extent of the aneurysm was not related to mortality. These results demonstrate that thoracoabdominal aneurysm resection after prior infrarenal aneurysmectomy is not associated with increased mortality or morbidity.

Femoropopliteal angioplasty. Factors influencing long-term success.

Prospective data was recorded on 217 percutaneous transluminal angioplasty (PTA) procedures performed in the superficial femoral and popliteal arteries over an 8-year period. After the initial procedure, patients were followed with serial noninvasive studies and, in 71 patients, repeat angiography. The mean follow-up period was 7 years (range, 2-11 years). Standard life-table survival analysis was used to assess the factors potentially affecting long-term outcome. Excluding an initial technical failure rate of 10%, overall patencies at 1, 3, and 5 years were 81%, 61%, and 58%, respectively. After the first year, the prognosis (i.e., failure rate) appears to be linear over the long term (i.e., up to 10 years). Factors negatively influencing long-term patency include the presence of diabetes mellitus, diffuse atherosclerotic cardiovascular disease, or threatened limb loss. Technical factors correlated with failure include lesion length, moderate eccentricity, and a poor post-PTA appearance.

Late failure of reversed vein bypass grafts.

Late failure of reversed vein bypass grafts is preceded by the appearance of stenotic lesions, which progress to total occlusion. These lesions appear either as intrinsic graft lesions or as new arteriosclerotic lesions in contiguous arteries. The present study summarizes the University of Pennsylvania experience with these lesions in 521 vein grafts inserted from 1979 to 1985. The grafts were grouped according to the site of the distal anastomosis; 231 above-knee popliteal (FP AK), 171 below-knee popliteal (FP BK), and 119 tibial (FT). The overall incidence of stenotic lesions was essentially identical with the three grafts (21%), but the relative incidence of intrinsic graft to arterial lesions was higher with the more distal grafts. The most common graft lesions developed adjacent to the proximal anastomosis, which is the narrowest part of a reversed vein graft. The popliteal artery was the most common site of outflow stenosis. There was negligible incidence of tibial lesions. The most common inflow arterial lesion was located in the common femoral and iliac arteries. The superficial femoral artery (SFA) was a rare site of inflow stenosis, even though it was at risk because 96 grafts originated from the SFA or popliteal artery. Sixty-seven per cent of the graft and 52% of the arterial lesions were treated successfully by percutaneous transluminal angioplasty; the rest had minor surgical revisions. This resulted in a 19%, 10%, and 9% improvement in 5-year patency for the FT, FP BK, and FP AK bypasses. These results justify an aggressive policy of graft surveillance to identify and treat stenotic graft lesions before graft occlusion.

Renovascular hypertension in children. Surgical repair with special reference to the use of reinforced vein grafts.

Surgical correction of renovascular hypertension in children is especially challenging because there is high incidence of bilateral renal artery lesions and stenosis of the abdominal aorta. Seventeen patients with severe hypertension, whose ages ranged from 2 to 16 years (mean 10.2 years), had surgical repair of these lesions from 1974 to 1987. Twenty-nine renal artery lesions were repaired. Twelve (71%) were bilateral, five (29%) were unilateral, and eight patients (47%) had abdominal aortic lesions (midaortic stenosis). Twenty-eight saphenous vein grafts and one splenorenal graft were used to bypass the renal artery lesions. The midaortic lesions were bypassed with Dacron grafts from the superceliac aorta to the aortic bifurcation. No operative deaths occurred. Nineteen of the 28 vein grafts were reinforced with a 6 mm diameter tubular Dacron mesh to prevent aneurysmal degeneration seen in three of nine unsupported vein grafts. Follow-up arteriograms were available in 15 patients up to 11 years after operation (mean 5.0 years). There has been no aneurysmal dilatation in the 19 mesh-supported grafts. The ratio of vein graft diameter to the diameter of the native aorta was 1.25 +/- 0.38 (+/- standard deviation) in unsupported grafts and 0.65 +/- 0.09 in mesh-supported grafts, representing a 92% increased diameter in the unsupported grafts. Three vein grafts (10.3%) required percutaneous transluminal angioplasty for late postoperative vein graft stenoses, but no stenotic lesions have developed at the aortic suture lines. One graft occluded 7 years postoperatively after replacement of an aneurysmal vein graft, and one early postoperative graft occlusion occurred, for a graft failure rate of 7%. Seventy-six percent of patients (13 of 17) are normotensive without medication, and 24% (4 of 17) are considered improved with hypertension controlled with a lower dose of medication. Our results attest to the safety and efficacy of this complicated surgery. Saphenous veins, supported by external Dacron mesh, appear to be a suitable graft material for renal reconstruction in this population.

The midaortic syndrome: diagnosis and treatment.

The midaortic syndrome is an unusual entity seen in children and adolescents. It is characterized by severe narrowing of the abdominal aorta with progressive involvement of the renal and visceral branches. Eleven patients (aged 5 months to 15 years) suspected of having midaortic syndrome were examined preoperatively and postoperatively. All patients had hypertension and were examined with midstream aortography. All aortograms showed a smooth, segmental stenosis of the abdominal aorta and severe bilateral proximal renal artery stenosis. In three patients, percutaneous transluminal angioplasty of the renal artery was attempted, two preoperatively and one for a postoperative stricture. None showed long-term success, presumably due to the progressive nature of the disease. Grafts were surgically placed in ten patients and produced successful results in nine.

Improved patency in reversed femoral-infrapopliteal autogenous vein grafts by early detection and treatment of the failing graft.

One hundred two femoral-infrapopliteal bypasses, in which reversed autogenous saphenous vein grafts were used, were performed from January 1978 to July 1984, in 94 patients with severe claudication (14%) or threatened limb loss (86%). Follow-up examinations at 3-month intervals during the first 18 months and at 6-month intervals thereafter were performed to document the return of ischemic symptoms or loss of peripheral pulses. Ankle pressure index and pulse volume recordings were also measured. A decrease in ankle pressure index equal to or greater than 0.2 or a pulse volume recording decrease of 5 mm or more with or without confirmatory symptoms were indications for repeat arteriography. Twenty-two primary graft or anastomotic stenoses were discovered in 19 grafts during follow-up. Seventy-eight percent of these lesions were treated primarily by percutaneous transluminal angioplasty and the remainder were treated by short proximal interposition grafts or patch graft angioplasty. Twenty-five grafts occluded during follow-up and all of these were considered to have failed for purpose of life-table analysis. Stenotic lesions, which were corrected before occlusion, were listed as continuously patent under secondary patency and as failed under primary patency life-table analysis. The secondary graft patency rate was 70% at 5 years, which was significantly higher (p less than 0.01) than the primary patency rate (47%), which was obtained without intervention. This 23% differential represents graft salvage achieved by careful surveillance and is reflected not only by improved patency but also by high limb salvage rates (86%) observed at 5 years.

Carotid endarterectomy in patients with heparin-induced platelet activation: comparative efficacy of aspirin and iloprost (ZK36374).

Patients with heparin-induced platelet activation who are reexposed to heparin may have recurrent thrombocytopenia, intravascular thrombosis, arterial emboli, or sudden death. To permit carotid endarterectomy in two patients with confirmed heparin-induced platelet activation, we compared the efficacies of aspirin and iloprost, a stable analogue of prostacyclin, in preventing heparin-induced platelet activation. In the first patient, although aspirin prevented both in vitro heparin-induced platelet aggregation (70% without and 7.5% with aspirin) and 14C serotonin release (48% without and 0% with aspirin), intraoperative administration of heparin resulted in an increase in plasma levels of platelet factor 4 from 8 to 260 ng/ml and beta-thromboglobulin levels from 29 to 39 ng/ml. In addition, the circulating platelet count decreased from 221,000 to 174,000 microliters, and 15% spontaneous platelet aggregation was observed. Fortunately, fibrinopeptide A levels remained less than 10 ng/ml intraoperatively, and no thrombotic complications occurred. In the second patient, aspirin did not prevent heparin-induced platelet aggregation in vitro (65% without and 41% with aspirin); however, iloprost (0.01 mumol/L) prevented both in vitro heparin-induced platelet aggregation (59.5% without and 0.0% with iloprost) and 14C serotonin release (56.7% without and 0.0% with iloprost). Therefore, a continuous infusion of iloprost was begun before administration of heparin and was continued until 20 minutes after reversal of heparin with protamine. After intraoperative administration of heparin, plasma levels of platelet factor 4 increased from 19 to 200 ng/ml, and beta-thromboglobulin levels increased from 56 to 76 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)