Investigation of patent foramen ovale as a mechanism for brain metastasis in patients without prior lung involvement.

PURPOSE: The mechanisms of brain metastasis are incompletely understood. Circulating tumor cells travel to the right heart and through the pulmonary circulation, where they may become lung metastases, and can circulate further to the left heart and brain. In patients who develop brain metastases without lung involvement, we hypothesized that cancer cells may travel directly from the right atrium to left atrium via a patent foramen ovale (PFO), akin to paradoxical embolism. If the prevalence of PFO is greater in these individuals compared to the general population (20-30%), PFO may play a role in brain metastasis, and prophylactic closure may provide benefit. Accordingly, we investigated the prevalence of PFO in patients with brain metastases without prior lung involvement. METHODS: We prospectively identified patients with brain metastases from a non-lung primary cancer with no preceding or concurrent lung involvement. Nine eligible participants underwent a transcranial Doppler study with intravenous agitated saline to assess for PFO. RESULTS: Among nine participants, primary cancers were breast (n = 6), upper gastrointestinal (n = 2), and thyroid (n = 1). A positive bubble study was identified in 2/9 (22.2%) participants: one female with breast cancer and one male with duodenal adenocarcinoma. No participants developed lung metastases on subsequent chest imaging. CONCLUSION: In this prospective pilot study, we found a similar prevalence of PFO in patients who developed brain metastases without preceding lung involvement compared to estimates for the general population. Through a larger study is needed, the development of brain metastases in these individuals may primarily reflect tumor-specific biological factors diecting metastasis organotropism.

Failure of angiography to accurately depict the extent of coronary artery narrowing in three fatal cases of percutaneous transluminal coronary angioplasty.

The angiographic and pathologic findings are described in three patients who died less than 24 h after failed percutaneous transluminal coronary angioplasty. In two of the three patients, coronary angiography performed before angioplasty disclosed apparently focal lesions in the left anterior descending and right coronary arteries. In these two patients quantitative angiographic analysis disclosed a minimal lumen cross-sectional area of 1.82 and 0.47 mm2, respectively, at the sites of apparently focal stenoses before angioplasty; corresponding percent lumen area narrowing measured 84% and 91%, respectively, by quantitative angiography at these two sites. In the third patient, coronary angioplasty was undertaken when the patient developed spontaneous occlusion of the right coronary artery several hours after diagnostic angiography. Retrospective quantitative angiographic analysis of the right coronary artery revealed a minimal lumen cross-sectional area of 1.14 mm2, with 85% lumen area narrowing at the site of subsequent total occlusion and angioplasty. In each of these three patients, necropsy examination disclosed that the distribution of coronary narrowing in the artery treated by angioplasty was in fact not focal; rather, in each of these three patients, the artery treated by angioplasty, as well as the extramural coronary arteries not treated by angioplasty, were severely narrowed by diffusely distributed atherosclerotic plaque. The angiographic and necropsy findings in these three patients document that coronary narrowing that remains occult by virtue of diffuse distribution may complicate evaluation of patients being considered for coronary angioplasty.

Benefit of intracoronary ultrasound in the deployment of Palmaz-Schatz stents.

OBJECTIVES: This study was designed to evaluate the changes in intrastent and angiographic dimensions when intravascular ultrasound imaging is used to direct the deployment of balloon-expandable Palmaz-Schatz stents in coronary arteries and saphenous vein grafts. BACKGROUND: Intravascular ultrasound provides more information than angiography in the imaging of intravascular structures. Previous studies have shown that obtaining a larger lumen (greater "acute gain") with coronary interventions such as stenting leads to less restenosis and subacute thrombosis. It is not clear whether the information obtained by intravascular ultrasound can be used to obtain a greater acute gain in lumen dimensions. METHODS: Forty consecutive patients undergoing Palmaz-Schatz stent implantation had intravascular ultrasound imaging performed after a good angiographic appearance was obtained. If the stent did not appear adequately expanded by intravascular ultrasound, or if the struts were poorly apposed to the arterial wall, further stent dilation with larger balloons or higher pressure inflations were performed. Twenty-nine patients had subsequent intravascular ultrasound imaging. Intrastent diameters and areas were compared from the initial to the final intravascular ultrasound studies. RESULTS: Of the 40 patients studied, only 5 (13%) had an adequate result by intravascular ultrasound despite an acceptable angiographic appearance in all patients. Six additional patients did not undergo subsequent intravascular ultrasound imaging. The other 29 patients all demonstrated a significant increase in intrastent minimal diameter (mean 19%), major diameter (11%) and cross-sectional area (34%) (p < 0.001 for all measurements). CONCLUSIONS: The use of intravascular ultrasound imaging in the deployment of balloon-expandable Palmaz-Schatz stents leads to a significant increase in intrastent dimensions (greater "acute gain").

An explanation for discrepancy between angiographic and intravascular ultrasound measurements after percutaneous transluminal coronary angioplasty.

OBJECTIVES: This study attempted to determine why there is a discrepancy between angiographic and intravascular ultrasound measurements after coronary balloon angioplasty. BACKGROUND: Previous studies have shown a poor correlation between angiographic and intravascular ultrasound measurements after percutaneous coronary balloon angioplasty. METHODS: After successful balloon angioplasty, 91 lesions in 84 patients were studied by intravascular ultrasound. Plaque morphology on intravascular ultrasound was classified as demonstrating a superficial injury if there was either no fracture or only a small tear that did not extend to the media versus a deep injury defined as the presence of a plaque fracture that reached the media. Measurements of minimal lumen diameter were compared between angiography and intravascular ultrasound. RESULTS: On ultrasound imaging, a superficial injury pattern was observed in 44 lesions, whereas a deep injury was seen in 47 lesions. There were no statistical differences at baseline in patient or lesion characteristics. In the superficial injury group there was a significant correlation between angiography and intravascular ultrasound for minimal lumen diameter (r = 0.67) and lumen cross-sectional area (r = 0.69). In the deep injury group there was a poor correlation for minimal lumen diameter (r = 0.05) and lumen cross-sectional area (r = 0.28). After balloon angioplasty, the angiographic appearance showed a normal contour in 34%, the presence of dissection in 38% or a hazy appearance in 23%. On ultrasound imaging after angioplasty, the superficial injury group comprised 65% of lesions with a normal angiographic appearance and 67% of lesions with a hazy appearance, whereas 77% of lesions with an angiographic diagnosis of dissection were in the deep injury group by ultrasound (p = 0.0005). CONCLUSIONS: These observations suggest that the discrepancies between angiographic and ultrasound measurements are due to differences in plaque morphology created by balloon dilation. Superficial injuries demonstrate similar results by angiography or ultrasound, whereas a deep injury to the plaque produces a difference in measurements between angiography and ultrasound. When angiography reveals a dissection, there is a high probability that intravascular ultrasound will demonstrate a plaque fracture extending to the media.

Angiographic and intravascular ultrasound predictors of in-stent restenosis.

OBJECTIVES: This study was performed to determine predictors of in-stent restenosis from a high volume, single-center practice. BACKGROUND: Intracoronary stents have been shown to reduce the restenosis rate as compared with balloon angioplasty, but in-stent restenosis continues to be an important clinical problem. METHODS: Between April 1993 and March 1997, 1,706 patients with 2,343 lesions were treated with a variety of intracoronary stents. The majority of stents were placed with high pressure balloon inflations and intravascular ultrasound (IVUS) guidance. Angiographic follow-up was obtained in 1,173 patients with 1,633 lesions (70%). Clinical, angiographic and IVUS variables were prospectively recorded and analyzed by univariate and multivariate models for the ability to predict the occurrence of in-stent restenosis defined as a diameter stenosis > or =50%. RESULTS: In-stent restenosis was angiographically documented in 282 patients with 409 lesions (25%). The restenosis group had a significantly longer total stent length, smaller reference lumen diameter, smaller final minimal lumen diameter (MLD) by angiography and smaller stent lumen cross-sectional area (CSA) by IVUS. In lesions where IVUS guidance was used, the restenosis rate was 24% as compared with 29% if IVUS was not used (p < 0.05). By multivariate logistic regression analysis, longer total stent length, smaller reference lumen diameter and smaller final MLD were strong predictors of in-stent restenosis. In lesions with IVUS guidance, IVUS stent lumen CSA was a better independent predictor than the angiographic measurements. CONCLUSIONS: Achieving an optimal stent lumen CSA by using IVUS guidance during the procedure and minimizing the total stent length may reduce in-stent restenosis.

Optimizing stent expansion with new stent delivery systems.

OBJECTIVES: The purpose of this study was to assess whether the newer stent delivery systems provide a stented lumen cross-sectional area (CSA) that is equal to the delivery balloon nominal dimensions. BACKGROUND: First generation stents were often not adequately expanded with their delivery system and frequently required higher pressure or a larger balloon after deployment. Newer stents were designed to optimize expansion with noncompliant, high-pressure balloons provided as the delivery systems. METHODS: Intravascular ultrasound (IVUS) was used to evaluate 38 stents in 32 patients after deployment at 14 to 16 atm with their delivery balloon system. Minimum stent lumen CSA and stent minimum lumen diameter (MLD) were measured by IVUS imaging. The manufacturer's expected stent diameter was defined as the balloon diameter measured by the company at the maximum pressure used. The manufacturer's expected stent area was calculated based on the manufacturer's expected stent diameter. RESULTS: The MLD (2.5 +/- 0.5 mm) and minimum stent CSA (6.0 +/- 1.7 mm(2)) by IVUS were significantly smaller than the manufacturer's expected stent diameter (3.5 +/- 0.4 mm) and area (9.5 +/- 1.9 mm(2)) (p < 0.0001, respectively). The mean MLD by IVUS was 72 +/- 8% of the expected stent diameter, and the mean minimum stent CSA by IVUS was 62 +/- 10% of the expected stent area. CONCLUSIONS: Despite moderately high-pressure inflations, the mean minimum stent CSA actually achieved was, on average, only 62% of the manufacturer's expected stent area. To optimize stent deployment, these IVUS observations should be considered during coronary artery stenting.

Bifurcation lesions: two stents versus one stent--immediate and follow-up results.

OBJECTIVES: The purpose of this study was to evaluate two different techniques of stent placement in bifurcation lesions. BACKGROUND: Although stent placement with dedicated techniques has been suggested to be a useful therapeutic modality for bifurcation lesions, limited information is available if stent placement on the side branch and on the parent branch provides any advantage over a simpler strategy of stenting the parent vessel and balloon angioplasty of the side branch. METHODS: Between March 1993 and April 1999, we treated a total of 92 patients with bifurcation lesions with two strategies: stenting both vessels (group B, n = 53) or stenting the parent vessel and balloon angioplasty of the side branch (group P, n = 39). Paired angiograms were analyzed by quantitative angiography, and clinical follow-up was obtained. RESULTS: Stent placement on both branches resulted in a lower residual stenosis (7.4 +/- 10.9% vs. 23.4% +/- 18.7%, p < 0.001) in the side branch. Acute procedural success was similar in the two groups (group B: 87% vs. Group P: 92%). In-hospital major adverse cardiac events (MACE) occurred only in group B (13% vs. 0%, p < 0.05). At the six-month follow-up, the angiographic restenosis rate (group B: 62% vs. Group P: 48%) and the target lesion revascularization rate (38% vs. 36%, respectively) were similar in the two groups. There was no difference in the incidence of six-month total MACE (51% vs. 38%). CONCLUSIONS: For the treatment of true bifurcation lesions, a complex strategy of stenting both vessels provided no advantage in terms of procedural success and late outcome versus a simpler strategy of stenting only the parent vessel.

Superiority of two-dimensional measurement of aortic vessel diameter in Doppler echocardiographic estimates of left ventricular stroke volume.

Attempts to measure left ventricular stroke volume utilizing the Doppler aortic flow method have found varying correlations between invasive thermodilution and non-invasive Doppler methods. Because stroke volume is the product of the Doppler flow velocity integral (that is, the area under the flow velocity curve) and the cross-sectional area of the vessel through which blood flows, both variables are potential sources of error. Previous studies have shown that the Doppler flow velocity integral can be measured with acceptable reproducibility in the ascending aorta. Consequently, in this study an attempt was made to determine empirically the optimal method for measuring aortic diameter and area. The diameter of the ascending aorta was measured utilizing four M-mode and seven two-dimensional echocardiographic conventions. Doppler aortic flow velocity patterns were recorded with a 2.25 MHz M-mode echocardiographic transducer from the suprasternal notch by mapping the ascending aorta until aortic peak flow velocity was recorded. In 19 adult patients undergoing cardiac catheterization for clinical indications, Doppler stroke volume estimates utilizing the various echocardiographic conventions for measuring aortic root diameter and area were compared with simultaneous measurements of stroke volume by the thermodilution technique. The best correlation (r = 0.87) with thermodilution stroke volume was obtained by estimating aortic area from the two-dimensional parasternal long-axis images with the aortic dimension measured distal to the aortic sinuses from the inner to inner wall. The data were related by the equation: Thermodilution stroke volume = (0.73) X (two-dimensional Doppler stroke volume) + 17 cc.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravascular ultrasound imaging.

Intravascular ultrasound imaging is a useful and promising modality that is capable of demonstrating the structure of blood vessel walls. It also provides a quantitative assessment of the amount of atheroma present that cannot be visualized by angiography. This article reviews the basic principles of intravascular ultrasound imaging and describes the clinical studies after balloon angioplasty evaluated by intravascular ultrasound imaging.

Cardiotoxicity of amitriptyline and doxepin.

The cardiotoxicity of the tricyclic antidepressants amitriptyline and doxepin were compared in an animal with acute overdose. The mean repetitive extrasystole threshold (RET) decreased 71.5% with amitriptyline and 27.5% with doxepin (mean blood levels 933 ng/ml and 1889 ng/ml). Physostigmine reversed these effects. Sodium bicarbonate had a variable effect on the lowered RET. The toxic arrhythmogenic effects of the tricyclic antidepressants can be measured by RET and are partly autonomic tone manipulation. In the same blood level range, doxepin is less toxic than amitriptyline.

Effect of amitriptyline antidotes on repetitive extrasystole threshold.

The effect of amitriptyline that leads to ventricular tachycardia was evaluated by the repetitive extrasystole threshold (RET) technique in 18 dogs. The RET was 28.8 +/- 7.9 mamp before and 8.2 +/- 5.3 mamp after amitriptyline, p less than 0.001. Physostigmine, propranolol, sodium bicarbonate, and left stellate ganglionectomy reversed the effect of amitriptyline on RET. We conclude that amitriptyline overdose predisposes to sudden death by lowering the ventricular fibrillation threshold. This cardiotoxic effect is mediated partly through the central nervous system and can be inhibited by increased plasma binding (bicarbonate), cholinergic stimulation (physostigmine), beta adrenergic blockade (propranolol), and sympathetic denervation (left stellate ganglionectomy).

Effects of isosorbide dinitrate on pulmonary hypertension in chronic obstructive pulmonary disease.

Eighteen patients with chronic obstructive pulmonary disease with pulmonary hypertension were studied to assess the hemodynamic response to acute oxygen administration and to oral isosorbide dinitrate (ISDN). All 18 patients had baseline hemodynamic measurements and hemodynamic measurements during low-flow nasal oxygen. Following a second baseline measurement, patients received either oral ISDN (11 patients) or placebo (7 patients) in a randomized, double-blind protocol. Heart rate decreased with oxygen administration but there were no other significant hemodynamic changes. With oral ISDN, there was a significant fall in pulmonary artery and brachial artery pressure. Cardiac output, right atrial pressure, pulmonary wedge pressure, and pulmonary vascular resistance all fell but not significantly. We conclude that oral ISDN is effective in reducing pulmonary hypertension in patients with chronic obstructive pulmonary disease.

Risk factor correlates of coronary calcium as evaluated by ultrafast computed tomography.

Coronary artery calcium is invariably associated with atherosclerosis and has been linked to an increased risk of coronary events. Ultrafast computed tomography (CT) was recently used to document the presence and relative quantity of coronary calcium. The use of the self-reported coronary risk factors to identify persons with coronary calcium as documented by ultrafast CT screening was examined in 458 men and 139 women aged 26 to 81 years (88% asymptomatic). All subjects underwent ultrafast CT scanning, and received a questionnaire and underwent an interview regarding medical and risk factor history. Total calcium score was calculated as the sum of lesion-specific scores, each calculated as the product of density > or = 130 Hounsfield units and area > or = 0.51 mm2. The prevalence of coronary calcium increased significantly (p < 0.01) by age group, and the greater the number of risk factors present, the greater the likelihood of calcium. From multiple logistic regression, age (p < 0.01), male sex (relative risk [RR] 3.03; p < 0.01), and history of smoking (RR 1.85; p < 0.01) and hypertension (RR 1.65; p < 0.05) were independently associated with the probability of detectable calcium. Among asymptomatic subjects, an association with hypercholesterolemia was also seen (RR 1.56; p < 0.05). The results demonstrate that cardiovascular risk factors can help in identifying the likelihood of coronary calcium.

Detection of coronary artery calcium by ultrafast computed tomography and its relation to clinical evidence of coronary artery disease.

Ultrafast computed tomography (CT) was used to evaluate the relation of coronary artery calcium, a marker of atherosclerosis, with a reported history of coronary artery disease (CAD) in 928 men and 290 women (mean age 53 +/- 10 years; 11% with previous CAD). Total calcium score was calculated as the sum of each lesion-specific score, calculated as the product of pixel area and density > 130 Hounsfeld units. Total score was 3 to 6 times greater (p < 0.01) and the probability of coronary artery calcium 30 to 40% greater (p < 0.01) in patients with a reported history of myocardial infarction, positive angiography, bypass surgery or angioplasty. From score cutoffs ranging from 1 to 500 for defining calcium, a negative test was accurate 93 to 98% of the time in ruling out CAD, whereas specificity increased from 43 to 93%; however, sensitivity decreased from 92 to 42%. A score cutoff of 50 showed modest sensitivity (78%) and specificity (71%); however, the predictive value for CAD from a positive test remained low (< or = 40%), regardless of score cutoff. From multiple logistic regression, total score was also an independent indicator of CAD after considering any effects due to age, sex and other CAD risk factors. Further study is needed to document the long-term prognostic use of coronary calcium screening, including criteria that best project future risk of CAD.

Laser-assisted versus mechanical recanalization of femoral arterial occlusions.

A randomized clinical trial was performed to test the hypothesis that a laser-heated probe is superior to standard techniques to reopen occluded femoral arteries. Twenty patients were treated with a standard guidewire and balloon dilation method. In a second group of 20 patients, the laser probe was initially used as a nonheated mechanical device. If the probe was unsuccessful in mechanically reopening the artery, an Argon laser was activated to heat the probe. The mean length of occlusion was 15.9 +/- 10.3 cm. The success rate for the laser probe was 15 of 20 (75%), which was not significantly different from the standard method, 19 of 20 (95%). Most of the success in the laser-probe group was due to the probe's mechanical properties. The laser probe was successful as a cold, mechanical device in 13 of 15 (87%) arteries. It was necessary to heat the probe in 5 patients. When heated, the laser probe assisted recanalization in 2 but perforated the artery in 3 cases. The results of this randomized trial do not support the hypotheses behind the use of the thermal laser probe. The laser probe functions primarily as a mechanical device. The thermal activation does not significantly improve the success rate without increasing the risk of perforation. This small additional benefit does not justify the large cost of current thermal laser devices. This controlled study also demonstrates a higher success rate in long occlusions than previous reports of mechanical balloon recanalization. This is due to a combination approach of retrograde and anterograde probing of the occluded segment.

Clinical utility of negative contrast intravascular ultrasound to evaluate plaque morphology before and after coronary interventions.

Although intravascular ultrasound (IVUS) is used for evaluation of plaque volume and lumen size as well as detection of vessel wall structures after catheter-based interventions, differentiation between the lumen and plaque structures can be difficult. This study attempted to evaluate the efficacy of negative contrast IVUS imaging for assessment of vessel wall morphology after coronary interventions. IVUS studies were performed in 67 lesions in 66 patients before and after coronary interventions. After the baseline ultrasound imaging run, warm 5% glucose solution was injected manually through the guiding catheter into the coronary artery to washout blood from the lumen to avoid speckled reflections from red blood cells (negative contrast). Quantitative measurements were obtained and plaque morphology was assessed for the presence and extent of medial dissections and intimal flaps. There was no difference in each quantitative parameter between baseline images and negative contrast images. The vessel wall boundary was clearly delineated from the lumen, which was defined as effective negative contrast in 51 of 67 lesions (76%). The baseline images revealed plaque dissection in 9 lesions (18%) and an intimal flap in 13 lesions (25%). In addition, 4 dissections (8%) and 16 intimal flaps (31%) were visualized during the infusion of negative contrast. Additional treatment was performed in 4 lesions (8%) based on the images with negative contrast. Negative contrast IVUS was more sensitive in demonstrating a plaque fracture than were baseline images. This method is useful for enhancing the diagnostic capability of IVUS imaging and may influence the decision-making process during interventional procedures.

Three-year outcome of endovascular treatment of superficial femoral artery occlusion.

HYPOTHESIS: Patency after primary percutaneous transluminal angioplasty (PTA) and stenting of superficial femoral artery (SFA) occlusions is better than historical experience with PTA alone. DESIGN: Consecutive case series of primary PTA with stenting, and follow-up with duplex imaging every 6 months (mean +/- SD follow-up, 32 +/- 15 months). SETTING: Veterans Affairs medical center. PATIENTS AND METHODS: Patients were 57 previously untreated men with 71 limbs having chronic atherosclerotic SFA occlusion with suprageniculate reconstitution and patent tibial runoff. Critical ischemia (Society for Vascular Surgery [SVS] category, 4-6) was present in 7 (10%), the remainder had intermittent claudication only (SVS, 1-3). INTERVENTIONS: Guidewire recanalization followed by PTA, Wallstent deployment, and adjunctive thrombolysis as necessary; 19 limbs (27%) required thrombolysis to manage periprocedural thrombosis. MAIN OUTCOME MEASURES: Cumulative patency, limb salvage, and complications. RESULTS: Length (mean +/- SD) of occlusion was 14.4 +/- 9.9 cm. Length of stented artery was 24.3 +/- 11.1 cm. Ankle brachial index increased from 0.59 +/- 0.14 to 0.86 +/- 0.16 (P<.001) after stenting. One- and 3-year patencies were as follows: primary, 54.6% +/- 6.3% and 29.9% +/- 6.6%; assisted primary, 72.3% +/- 5.6% and 59.0% +/- 6.8%; and secondary, 81.6% +/- 4.8% and 68.3% +/- 6.5%. Three-year secondary patency when periprocedural thrombolysis was required was 35.7% +/- 12.5% compared with 70.6% +/- 7.4% for limbs not requiring periprocedural thrombolysis (P=.02); the differences in occlusion length and severity of ischemia were not significant between these 2 groups. Limbs undergoing adjunctive PTA during angiography 6 to 12 months after initial stenting had 63.0% +/- 13.3% patency at 3 years compared with 100% patency in limbs not requiring PTA at 6 to 12 months angiography (P=.046). Periprocedural mortality and morbidity were 2.8% and 15.5%, respectively. Three of the 7 limbs with critical ischemia underwent amputation during follow-up compared with 2 (3%) of 64 limbs with functional ischemia (chi(2) test, P<.006). A mean of 1.8 endovascular interventions per limb were performed. CONCLUSIONS: Percutaneous transluminal angioplasty and stenting yielded higher patency rates than historical controls undergoing PTA alone. When periprocedural thrombolysis is required, subsequent patency appears to be significantly worse. Poor results after PTA and stenting of limbs with critical ischemia and the need for additional endovascular therapy limit the technique's utility.

The reproducibility of intravascular ultrasound imaging in vitro.

To determine which factors may affect the image quality when an intravascular ultrasound catheter is used in vivo, the influence of blood, temperature change, and contrast media were evaluated. In addition, to confirm the reproducibility of intravascular ultrasound imaging to measure cross-sectional lumen area, intraobserver and interobserver variability were determined. The findings indicated that ultrasound images in blood are mildly attenuated, that changes from room temperature to body temperature do not have a significant impact on the image quality, that contrast media attenuates the image intensity in a dose-dependent manner, and that the intravascular ultrasound imaging catheter provides a reproducible method for measuring arterial lumen area with excellent intraobserver and interobserver correlation.

Estimating the 3D skeletons and transverse areas of coronary arteries from biplane angiograms.

A method for estimating the three-dimensional (3D) skeletons and transverse areas of the lumens of coronary arteries from digital X-ray angiograms is described. The method is based on the use of a 3D generalized cylinder (GC) consisting of a series of 3D elliptical disks transverse to and centered on a 3D skeleton (medial axis) of the coronary arteries. The estimates of the transverse areas are based on a nonlinear least-squares-error estimation technique described by D.W. Marquardt (1963). This method exploits densitometric profiles, boundary estimates, and the orientation of the arterial skeleton in 3-space and includes an automatic artery tracking procedure. It applies an adaptive window to the densitometric profile data that are used in the parameter estimation. Preliminary experimental tests of the procedure on angiograms of in vivo human coronaries and on synthetic images yield encouraging results.

Determinants of patency after percutaneous angioplasty and atherectomy of occluded superficial femoral arteries.

BACKGROUND: Patients undergoing percutaneous recanalization of chronically occluded superficial femoral arteries were studied to determine which factors correlated with 1-year patency. Immediate change in ankle:brachial index (ABI), length of occlusion, tibial run-off, and the performance of supplemental catheter atherectomy were evaluated. METHODS: Eligible patients had at least one patient tibial run-off vessel and the absence of limb-threatening ischemia. Recanalization was performed via passage of a guidewire followed by balloon angioplasty. Tibial run-off was scored based on a modification of the angiogram scoring system of the Society for Vascular Surgery and the International Society for Cardiovascular Surgery. Supplemental transcutaneous extraction catheter atherectomy was randomly assigned to a sub-group of patients after initial experience with the recanalization technique. Clinical follow-up was employed to determine patency. RESULTS: Forty-two of 57 attempts (74%) at recanalization were immediately successful. Overall 1-year patency was 40% in 40 limbs that could be followed. In limbs with balloon angioplasty alone (n = 23), patency was 43% compared with 35% in those having supplemental atherectomy. Tibial run-off did not vary significantly between patent and occluded groups. When ABI increased by 0.3 or more, patency was 56% compared with 26% when the ABI increase was less than or equal to 0.1 (P = 0.13). Occlusion length averaged 18.1 +/- 10.6 cm for all limbs and did not vary significantly between early successes and failures. Limbs with short occlusions (less than or equal to 5 cm, n = 8) had 63% patency compared with 38% patency for limbs with long occlusions (greater than 25 cm, n = 16), but the difference was not significant by analysis of variance. CONCLUSIONS: An initial change in ABI was most predictive for patency, whereas no correlation with tibial run-off was demonstrated. Atherectomy did not increase patency. Short occlusions were more likely to remain patent than long ones, but overall patency was lower than described in other series.