Directional Atherectomy Research Articles

720-1 Incidence of and Factors Associated with Abrupt Closure in Patients Undergoing Elective, New Device Angioplasty in Native Coronary Arteries

To determine the incidence and predictors of abrupt closure (TIMI flow = 0 or 1) in patients undergoing new device angioplasty (NDA), we studied the hospital records and qualitative morphologic and quantitative angiographic methods of 1,983 patients with unfavorable lesion morphologies treated electively in native coronary arteries with intracoronary stents (N = 96), extraction atherectomy (TEC; N = 27). directional atherectomy (N = 563), rotational atherectomy (N = 775), or laser (N = 522). The overall incidence of abrupt closure was 3.9% (78/1983), with 2.1% (42/78) occurring during the procedure and 1.8% (36/78) occurring out-of-Iab (1 patient with both inand out-of-Iab abrupt closure). Among NDA, TEC (14.8%) and stents (8.3%) had relatively higher frequencies of abrupt closure compared to other NDAs (mean of 3.5%). Multivariate analysis of demographic and lesion characteristics revealed the following predictors associated with either in-lab or out-oflab abrupt closure:Independent PredictorsOdds Ratio95% C.I.p valueUnstable angina2.011.13-3.57<0.05Lesion length ≥ 10 mm2.001.26-3.19<0.005Angulation ≥ 45 °1.821.09-3.04<0.05C.I. = confidence interval C.I. = confidence interval The sole independent predictor for out-of-lab only abrupt closure was dissection (Odds Ratio = 3.11, p < 0.005). We conclude that:(1) The incidence of abrupt closure (both in- and out-of-lab) was 3.9% in patients undergoing elective new device angioplasty, with nearly equal distribution of in- and outof- lab occurrences: (2) Unstable angina. lesion length ≥ 10 mm, and angulation ≥ 45° predicted either in- or out-of-lab abrupt closure, whereas dissection was the sole significant predictor of out-of-lab only abrupt closure: and (3) both lesion-related (thrombus-containing lesions for extraction atherectomy) and device-related factors (stents with subacute thrombosis) added to the acceptable rates of abrupt closure with these new devices for lesions unfavorable for conventional angioplasty.

1018-47 A Matched Comparison of the Longterm Outcome of Directional Coronary Atherectomy versus Coronary Stenting

To compare the renarrowing process after atherectomy (DCA) and stenting, we reviewed the cineangiograms from a prospectively collected series of 234 matched DCA and stent patients (pts) with identical baseline clinical and angiographic characteristics. In addition, we explored whether the process of luminal renarrowing was related to the extent or mechanism of luminal improvement in matched pts with comparable lesion location, vessel size (RD), lesion severity (MLD) and acute gain. Multivariate analyses were performed to determine the correlates of minimal lumen at follow-up and lumen loss. Matching was considered adequate since lesion distribution, RD (3.09 vs 3.09 mm) and MLD (1.12 vs 1.12 mm) were equal in both groups. Stenting lesulted in a larger increase in MLD than DCA (1.41 vs 1.20 mm; p = 0.0002), similar late loss (0.57 vs 0.66 mm; p = NS) with subsequently a larger MLD at follow-up (1.96 vs 1.66 mm; p = 0.0001). However, when additional matching (n = 150 pts) for acute gain (1.34 vs 1.33 mm) was performed, late lumen loss was significantly smaller after stenting (0.52 vs 0.75 mm; p = 0.007) leading to a favorable long-term MLD (1.90 vs 1.66 mm; p = 0.004) when compared with DCA. Multivariate analysis revealed device type, vessel size and lumen gain as independent predictors for MLD at follow-up. The changes in MLD are shown in cumulative distribution curves: Multivariate analysis of MLD at follow-up Intercept Coefficient p-value -0.63 RD 0.19 0.12 MLD pre 0.76 0.004 Gain 0.67 0.0001 Device -24 * 0.003 DCA = 1. STENT = 0 the long-term angiographic outcome of stenting seems more favorable than of directional atherectomy due to a larger acute luminal gain and a substantial reduction in late luminal loss. It appears that the late outcome after an intervention is not only related to extent of luminal improvement but also to the mechanism of acute gain (device type).

797-1 Differential Expression of Tissue Factor Protein in Directional Atherectomy Specimens from Patients with Stable and Unstable Coronary Syndromes

Tissue factor (TF) is a cell membrane-associated protein that catalyzes the rate-limiting step of the extrinsic coagulation pathway, which is the major source of thrombin production in-vivo . To examine the potential role that TF may play in the pathogenesis of different coronary syndromes, we studied directional coronary atherectomy specimens ftom 57 patients, using immunohistochemical techniques. Patients were classified according to their admission diagnosis as having either an unstable coronary syndrome, which required the presence of rest angina or post-infarction (<1 week) angina, or stable coronary syndromes which included stable, progressive and newonset angina without rest chest pain. Lesions were also classified as a denovo or a restenosis lesion. Frozen sections were examined for the presence of TF using a murine IgG monoclonal antibody against human tissue factor. Samples were read independently by two investigators without knowledge of the clinical information. The results were expressed dichotomously as positive or negative using human skin sections as a positive control and a nonsense murine monoclonal antibody as a negative control. Statistical analysis were performed using a Chi-Square or Fischer's Exact Test. For the entire study group, TF was detected in 15 (45%) of 33 patients with unstable coronary syndromes versus only 3 (13%) of 24 patients with stable coronary syndromes; p ≤ 0.02. Moreover, within the subgroup of patients with unstable coronary syndromes, TF protein was detected in 14 (61%) of 23 patients with de-novo lesions versus only 1 (10%) of 10 patients with rest angina from a restenosis lesion; p ≤ 0.01. An additional 7 patients with stable coronary syndromes due to a restenosis lesion were also all negative for TF, for an overall incidence of only 1 (6%) of 17 restenosis lesions. In conclusion, tissue factor is readily detected in atherectomy specimens from de-novo lesions in patients with unstable coronary syndromes, suggesting a role for this protein in the pathogenesis of this disease process. Conversely, tissue factor is rarely detected in patients with restenosis lesions even if the clinical presentation is an unstable coronary syndrome. These results may have implications in regard to the management of patients with unstable angina from de-novo lesions and all patients with recurrent symptoms from restenosis lesions.

1001-26 Local Dissolution of Intracoronary Thrombus with Urokinase Using the Dispatch™ Catheter: Clinical Studies

The Dispatch™ Catheter is a new local drug delivery device which allows for the prolonged infusion of therapeutic agents at an angioplasty site while still maintaining distal coronary perfusion. To determine the efficacy of this device in dissolving intraluminal clot with local urokinase infusion, 29 patients with thrombus-containing stenoses were treated with the Dispatch™ catheter either prior to (n = 16) or following (n = 13) coronary angioplasty or directional atherectomy. The study group consisted of 15 males and 14 females with a mean age of 58.1 years. Clinical diagnoses included unstable angina (n = 14), acute myocardial infarction (n = 11) or post infarction angina (n = 4). Urokinase was infused at either 10,000 unitlcc (n = 22) or 30,000 units/cc (n = 7) at 0.5 cc/min for up to 30 minutes. All coronary angiograms were analyzed to determine Thrombus Score (0 – 3), TIMI flow, and quantitative coronary measurements pre and post Dispatch™ therapy. (Thrombus Score: 0 = no thrombus, 1 = possible thrombus, 2 = definite thrombus < 3 mm, 3 = definite thrombus > 3 mm). Infusions of urokinase for 30 mins were well tolerated in 25 patients without adverse clinical, hemodynamic or electrical sequelae. In the remaining 4 patients, limited infusions were tolerated only for 2.5, 5, 6 and 11 mins because of chest pain with EKG changes secondary either to sidebranch occlusion or inadequete distal perfusion. For the entire study group, Thrombus Score decreased from 2.0 ± 0.7 to 0.5 ± 0.8, TIMI Flow increased from 2.1 ± 1.3 to 3.0 ± 0.0, and minimal lumen diameter increased from 0.70 ± 0.59 to 1.58 ± 0.51 mm (all p < 0.01). Distal embolization, no-reflow, and abrupt closure were not observed in any patient. Reduction of thrombus-containing stenoses and dissolution of intracoronary thrombus can be rapidly achieved in patients with infusions of limited quantities of urokinase with the Dispatch™ catheter. Sidebranch occlusion and inability to dilate coronary stenoses with inadequate distal perfusion may limit the duration of drug infusion with this device.

768-1 Coronary Lesion Histology in Stable, Unstable and Evolving Angina Pectoris

We performed a histologic analysis of coronary lesions obtained by directional atherectomy from 100 patients with stable, unstable and evolving angina pectoris. Histologic analysis was performed by two pathologists unaware of the clinical history or angiographic findings. This included notation of the presence or absence of various matrix components and quantitative scoring (0-3+) of cellular lesion components. Forty-seven patients (47%) had native coronary lesions. Twenty-five patients (25%) had restenosis after previous balloon angioplasty and twenty-eight (28%) were treated for primary saphenous vein graft disease. There were no differences in the average histologic appearance of atherosclerotic lesions resulting in stable, unstable and evolving angina pectoris. Saphenous vein graft lesions were typically rich in dense connective tissue and extracellular lipid and mononuclear infiltrate. Restenosis lesions were rich in acid mucopolysaccharide and vascular smooth muscle cells and revealed no histologic differences according to the clinical syndrome. Native coronary artery lesions, from patients with unstable angina, more often contained organizing thrombi (30% vs 0%, P < 0.05), cholesterol crystals (20% vs 0%, P < 0.05) and harbored a more intense vascular smooth muscle cell infiltrate (2.1 vs 1.4, P < 0.05) when compared to lesions from patients with stable angina pectoris. There was no difference in the intensity of inflammatory or foam cell infiltration. Vascular smooth muscle cells, appearing as intimal hyperplasia, are more prominent in lesions resulting in unstable angina. There is, however, no difference in the intensity of inflammatory or foam cell infiltrate. The histologic appearance of coronary lesions producing the syndrome of unstable angina pectoris is quite heterogenous. In order to establish the role of inflammation in the development of non-fatal acute coronary syndromes, improved sampling methods or a larger sample size will be required.

1012-105 Endothelin Immunoreactivity in Human Coronary Atherosclerosis

Coronary atherosclerosis and restenosis are disease processes involving cell proliferation and activation of growth factors. Endothelin-l (ET-l), a vasoconstrictor and mitogenic peptide, is produced from its precursor Big-ET. Coronary plasma ET concentrations are elevated in coronary atherosclerosis and following coronary interventions. The current study was designed to test the hypothesis that ET is produced and present in human coronary atherosclerotic and restenotic lesions and localized to both endothelial and nonendothelial cells. Twenty coronary lesions were obtained utilizing directional atherectomy. Immunohistochemistry for endothelins was performed with rabbit polyclonal ET-l and Big-ET antiserum without cross reactivity between Big-ET and ET-1 antisera. In addition, staining for specific cell types, including macrophages (KP-1), endothelial cells (Factor VIII), and myointimal cells (actin), was performed. Eight primary native lesions, six restenotic lesions, and six vein graft (VG) lesions were studied. In all lesion types, intracellular Big-ET and ET-1 were present and in the extracellular matrix and colocalized to area with endothelial cells, macrophages, fibroblasts, and myointimal cells. ET-1 and Big-ET were colocalized to area with myointimal cells only in the primary native lesions. This study demonstrates the presence of Big-ET and ET-1 in coronary and VG atherosclerotic and restenotic lesions. This study suggests that ET is produced locally in the atherosclerotic and restenotic lesions by endothelial and nonendothelial cells. ET may playa role in the changes in tissue architecture and pathogenesis of coronary and VG atherosclerosis and restenosis.

1018-46 Influence of Randomized Trials on Clinical Practice: A Comparison of Directional Atherectomy and New Device Use Before and After the CAVEAT Trial at CAVEAT Sites

In order to evaluate the impact of the Coronary Angioplasty versus Excisional Atherectomy Trial (CAVEAT-I) on practice patterns of coronary intervention, a week-long registry of the “universe” of all coronary interventions performed at 35 investigational sites between April 18 and 22, 1994 was compared with a similar registry obtained before the trial was initiated. A total of 97% of sites responded. Additional sites which took part in CAVEAT-II comparing DCA and PTCA in vein grafts were also audited for generalizability:DeviceCAVEAT-I sitesCAVEAT-II sitespre-CAVEATpost-CAVEATpost-CAVEATn%n%n%PTCA53983.844.368.530778.1DCA6910.79114.1399.9Other355411317.54712* P < 0.0001*p value for comparison of CAVEAT-I sites pre vs. post CAVEAT p value for comparison of CAVEAT-I sites pre vs. post CAVEAT There has been a significant decline in the proportion of procedures relying exclusively on balloon angioplasty and paradoxically, despite the negative findings of CAVEAT-I, a noteworthy trend towards an increase in use of DCA and other devices at CAVEAT sites. This paradoxic increase in trend was still evident when subgroup analysis of American and European CAVEAT-I sites was performed. These findings suggest that even among investigators in the trial, there is a lack of influence of CAVEAT-I data on clinical practice patterns.

903-15 Expression of 92 kDa Gelatinase in Primary Atherosclerotic vs Restenotic Coronary Lesions: Evidence for Mechanical Plaque Stabilization

Rupture of atherosclerotic plaque resulting in intravascular thrombosis and myocardial infarction (MI), while a common sequelae of primary atherosclerotic lesions, is an uncommon consequence of restenosis. We hypothesize that the rarity of MI associated with restenotic lesions is a result of cellular and biochemical modifications induced by the local response to balloon injury rendering the site resistant to rupture (plaque stabilization). Clinical and angiographic features of pts presenting with symptomatic primary (n = 24) or restenotic coronary lesions (n = 12) who underwent directional atherectomy were compared. Histologic analysis and immunostaining forthe matrix degrading enzyme, 92 kDa gelatinase, were performed on each atherectomy specimen. There was no significant difference between the 2 groups regarding age, gender, incidence of diabetes, smoking, hypertension, hypercholesterolemia or previous MI. Extent and distribution of disease, vessel caliber and % stenosis were not significantly different between groups. However, 8% of primary lesions were hypercellular compared to 75% (p = 0.0001) of restenotic specimens. 92 kDa gelatinase was expressed in 79% of primary lesions vs 0% of restenotic specimens (p = 0.0001). Thrombus was identified in 54% of primary lesions vs 22% of restenotic lesions (p < 0.05). These findings suggest that, independent of clinical or angiographic influences, balloon injury induced increased lesion cellularity and reduced expression of 92 kDa gelatinase, possibly conferring less propensity for plaque rupture and thrombosis.

Treatment of Anastomotic Bypass Graft Stenosis with Directional Atherectomy: Short-term and Intermediate-term Results

Areas of anastomotic stenosis in lower-extremity bypass grafts (BPGs) were treated by means of directional atherectomy (DA) in hopes of achieving better patency rates than have been reported with percutaneous transluminal angioplasty (PTA). During a 4-year period, 17 patients (11 men and six women) with 23 areas of anastomotic stenosis in 18 lower-extremity BPGs were selected for treatment with DA. Urokinase thrombolysis was initially performed in eight BPGs that were thrombosed at the time of presentation. Adjunctive preatherectomy PTA was performed in six lesions, and postatherectomy PTA was performed in three lesions. The technical success rate for DA was 92% (23 of 25 sites). There was less than 50% restenosis at 74% of the areas of stenosis (14 of 19 sites), with a mean follow-up time for the sites of 13 months. The graft patency rate was 88% (14 of 16 grafts), with a mean follow-up time for the grafts of 14 months. Areas of stenosis treated with DA alone had the same patency rates as those treated with DA and PTA. DA is an effective treatment method for anastomotic peripheral arterial BPG stenosis. The intermediate-term patency rates following DA are superior to those reported for PTA and similar to those reported for surgical revision.

Immediate and long-term clinical outcome of coronary angioplasty in patients aged 35 years or less.

To study the immediate and long-term clinical success of percutaneous transluminal coronary angioplasty in patients aged 35 years or less. Patients undergoing percutaneous transluminal angioplasty were prospectively entered into a dedicated database. Clinical and angiographic data on all patients aged 35 years or less were reviewed. Follow up data were collected by interview during outpatient visits, by questionnaire, or from referring physicians. A tertiary referral cardiac centre. 57 patients aged 35 years or less (median 33, range 22-35) underwent coronary angioplasty because of unstable angina (32 patients), stable angina (23 patients), acute myocardial infarction (1 patient), and documented ischaemia in a cardiac transplant patient. The primary clinical success rate (reduction in diameter stenosis to < 50% without in-hospital events) was 88%. A major procedure related complication occurred in 5 patients (9%): one patient died, two patients sustained an acute myocardial infarction, two patients underwent emergency bypass surgery, and in three patients repeat angioplasty was performed before hospital discharge. In 2 patients (4%) coronary angioplasty did not significantly reduce the diameter stenosis but there were no associated complications. A total of 60 lesions were attempted (balloon angioplasty in 57, directional atherectomy in 2). The initial angiographic success rate was 92%. The median (SD) follow up was 4.7 (3.0) years. During follow up 7 patients (12%) died, 10 sustained a myocardial infarction (18%), and 28 patients (49%) underwent repeat revascularisation (coronary artery bypass grafting in 7 (12%) and repeat angioplasty in 21 (37%)). The estimated 5 year survival and event-free survival (Kaplan-Meier method) was 87 (9)% and 50 (13)%, respectively. Multivariate logistic regression analysis showed that hypertension and the extent of vessel disease were the only independent predictive factors for event free survival. In young patients coronary angioplasty had a high immediate success rate but many needed repeat revascularisation procedures during the follow up period and survival was not improved. Coronary angioplasty in young patients should be regarded as a palliative procedure.

Progression of coronary stenosis after directional atherectomy at the proximal segment of treated sites

Progression of coronary stenosis after directional atherectomy at the proximal segment of treated sites

DCA Not Superior for Ostial LAD Stenoses

Ostial stenoses of the left anterior descending (LAD) coronary artery are often resistant to successful treatment with balloon angioplasty. This substudy compares directional atherectomy (DCA) with PTCA for ostial and nonostial LAD lesions using data from the randomized CAVEAT trial. Almost half the patients in this trial had LAD lesions (n=563), and 74 of these …

Directional Atherectomy of "Protected" Left Main Stenoses

The need for left main revascularization in patients with a patent bypass graft to either the left anterior descending or left circumflex coronary arteries (protected) is an increasingly frequent problem. PTCA of such lesions has been associated with a high restenosis rate and need for repeat procedures including surgery. This may be due to unique …

Ultrastructural characteristics of cellular reaction after experimentally induced lesions in the arterial vessel.

Restenosis after angioplasty occurs with an incidence of 20-50% and remains a major drawback. Certain randomized studies suggest that a bigger post-angioplasty lumen predicts a better long-term outcome. Conversely other studies showed a better outcome with limited injury. The present study aimed to investigate the depth of the lesion and relate this to cellular alterations after graded vascular injury. Vessel segments of 30 pigs underwent injury using a directional atherectomy catheter. Vessels were assigned according to the extent of injury to Group 1 (intima lesion) or Group 2 (media injury). 2 hours to 7 days after injury, 68 arteries showing 41 intimal and 27 media lacerations were excised and processed for histology and transmission electron microscopy. Immediately after injury, thrombus formation was found at the site of the altered segment. A marked, transient infiltration of polymorphonuclear leukocytes (PMN) occurred only if the media was lacerated, starting within the first hours and increasing up until the 12 hours time point. The cellular infiltration was followed by a transformation of contractile myocytes to a synthetic subtype. The ratio of myofilaments to organelles decreased. A pronounced myoproliferative response was found in Group 2 after 7 days (p < 0.01), whereas only moderate tissue hyperplasia was seen in Group 1. The data presented provide evidence that the cellular alteration of injured vessels begins immediately. Subsequent to an initial temporary PMN infiltration, an activation of local myocytes occurs at a very early stage. In particular, a myoproliferative response was found only after deep injury with rupture of the internal elastic lamina.

Optimal use of directional coronary atherectomy is required to ensure long-term angiographic benefit: A study with matched procedural outcome after atherectomy and angioplasty

Objectives. This study was designed to examine whether restenosis is related to the extent or mechanism of lumen improvement and to explore angiographic determinants of optimal atherectomy.Background. Directional atherectomy induces a greater extent of immediate gain and late loss but has not been found to yield a better late angiographic lumen than angioplasty in randomized trials. The difference in lumen renarrowing may be related to either the extent or the mechanism of immediate gain. The design of previous studies has precluded the detection of a device-specific effect on restenosis.Methods. A retrospective analysis was based on matching a prospectively collected series of 80 native coronary arteries successfully treated with atherectomy with a prospectively collected series of 80 native coronary arteries successfully treated with balloon angioplasty. Angiographic analysis was performed in 160 lesions to explore whether a specific device-related effect exists. Multivariate analyses were performed to determine the correlates of minimal lumen diameter at follow-up and late lumen loss and to identify the procedural characteristics for optimal atherectomy.Results. Matching resulted in two comparable groups with equivalent baseline clinical and stenosis characteristics. By study design, atherectomy and angioplasty resulted in similar mean (±SD) immediate lumen gain (1.15 ± 0.44 vs. 1.10 ± 0.40 mm, p = 0.50). However, lumen loss was more pronounced after atherectomy, and, thus, the minimal lumen diameter at follow-up differed significantly between the two groups (1.78 ± 0.57 vs. 2.00 ± 0.56 mm, p = 0.001). Device type was retained in the multivariate analysis as an independent predictor of late minimal lumen diameter and lumen loss. Multivariate analysis identified vessel size and immediate gain as determinants of optimal atherectomy.Conclusions. Restenosis is a consequence not only of the extent of lumen improvement but also of the mechanism of vessel wall injury (debulking vs. dilating). While performing atherectomy, the operator should strive for an optimal procedural result to accommodate an increased intimal hyperplastic response.

Directional atherectomy of left main stenoses.

Balloon angioplasty (PTCA) of left main (LM) stenoses is limited by frequent clinical restenosis. Directional coronary atherectomy (DCA) may be an effective alternative to PTCA due to its ability to achieve a greater postprocedural luminal diameter when treating bulky, eccentric plaques and aorto-ostial lesions. We analyzed the acute and long-term results following 24 DCA procedures in 22 patients with "protected" LM lesions. Acute success (residual stenosis < or = 40%, no major ischemic complications) was 88% overall, 100% in 13 planned procedures, and 73% in 11 adjunctive DCA procedures that followed suboptimal PTCA. Mean LM stenosis was reduced from 86% to 13% (P < 0.01). There were no procedural complications directly attributed to DCA. At a mean of 24 +/- 3 months, the clinical restenosis rate was 16%, survival was 100%, and event-free survival (freedom from death, MI, or repeat lesion-related interventions) was 89%. We conclude that DCA in protected LM lesions (1) can achieved excellent angiographic results with low procedural complication rates, (2) may succeed where PTCA yields suboptimal results, and (3) may provide late clinical outcomes superior to those of balloon angioplasty.

Percutaneous transluminal atherectomy of the superficial femoral and popliteal arteries: long-term results in 48 patients.

Evaluate retrospectively the long-term primary patency of directional atherectomy (DA) in the femoropopliteal arteries. DA was used alone in 59 patients (47%) or in combination with predilatation to allow passage of the device (43%) or after thrombolysis (10%) to treat 127 (93%) excentric atherosclerotic stenoses and nine (7%) occlusions of the femoropopliteal arteries. Forty-eight patients were followed by telephone interview, scheduled outpatient visits, color-flow Doppler evaluation, and angiography for 1-36 months (mean 16.9 months). Technical success (reduction of the stenosis or occlusion to less than 30% luminal diameter) was achieved in 110 lesions (80.3%) during 48 procedures in 37 patients. Mean luminal diameter was increased 54% with a concomitant increase in mean ankle/brachial indices of 0.33. According to Kaplan-Meier survival curves, patency at 12 and 24 months was 88% and 75%, respectively. When patients who retained patency but developed restenosis were excluded, the probability of patency at 12, 24, and 36 months was 76%, 58%, and 32%, respectively. Major and minor complications occurred in 15 (21.4%) procedures each for a total complication rate of 42.8%. Based on our results, DA is an effective method for percutaneous treatment of atherosclerotic disease involving the femoropopliteal arteries. It has similar patency but a relatively high complication rate compared with PTA.

Quantitative polymerase chain reaction (PCR) to analyze messenger-RNA expression in tissue obtained by directional atherectomy.

There is a widely recognized need to evaluate gene expression in human vascular plaque tissue. Directional atherectomy made it possible to sample plaque tissue from primary stenoses and subsequently from restenoses from one individual. Conventional approaches to analyze mRNA content of lesions, such as Northern blot analysis, and slot blot analysis are not sensitive enough to evaluate mRNA levels in atherectomy specimens limited by low cell number or low copy number per cell. The purpose of this study was to investigate whether gene expression, as reflected in mRNA copy number, in atherectomy biopsies, could be sufficiently analyzed by quantitative polymerase chain reaction (PCR). The authors applied PCR to detect platelet-derived growth factor-A mRNA expression in 12 human lesions sampled percutaneously by directional atherectomy. After reverse transcription, specific amplification of the resulting cDNA was performed. This was successful with cDNA from less than 0.5 microgram of total cellular RNA. To quantitate mRNA content of specimens, the authors coamplified cDNA copies of mRNA from lesions and from a synthetic reference RNA in the same reaction vessel. Quantitative PCR is best applied if tissue is more than 45 mg in weight and of high cellularity with low calcification. This method allows quantitation of mRNA in human primary and restenotic lesions, and it complements histochemical approaches and in situ hybridization of coronary and peripheral atherectomy specimens.

Directional atherectomy in the treatment of anastomotic neointimal hyperplasia associated with prosthetic arterial grafts: Technique and preliminary results

The development of anastomotic neointimal hyperplasia is a common cause of late prosthetic arterial bypass graft failure. The cost and morbidity of graft failure are high, hence the widespread use of graft surveillance programmes in order to detect graft-related stenoses before they progress to occlusion. However, the optimal treatment of stenoses secondary to neointimal hyperplasia is not clear, with a number of authors reporting poor results with both balloon angioplasty and surgical revision. We report our early experience with the Simpson atherectomy catheter in the treatment of anastomotic neointimal hyperplasia associated with prosthetic arterial grafts at eight sites in seven patients. A high technical success rate may be expected and further long-term studies of this mode of treatment are indicated.

Adjunctive Thrombolytic Agents With Coronary Interventional Techniques

Thrombolytics are used in a variety of interventional procedures, including direct lytic therapy, and in conjunction with PTCA, directional atherectomy and intracoronary stenting. The dosage and variety of thrombolytics is controversial. This article examines all potential uses of thrombolytics and reports on major trials using thrombolytics in these situations.