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Biomedical subjects

J B Simpson

Publications and source records attributed to J B Simpson.

At least 37 records · Page 2Linked to original sources
PubMed1993

Proliferation in primary and restenotic coronary atherectomy tissue. Implications for antiproliferative therapy.

On the basis of animal models of arterial injury, smooth muscle cell proliferation has been posited as a dominant event in restenosis. Unfortunately, little is known about this proliferation in the human restenotic lesion. The purpose of this study was to determine the extent and time course of proliferation in primary and restenotic coronary atherectomy-derived tissue. Primary (n = 118) and restenotic (n = 100) coronary atherectomy specimens were obtained from 211 nonconsecutive patients. Immunocytochemistry for the proliferating cell nuclear antigen (PCNA) was used to gauge proliferation in the atherectomy specimens. The identity of PCNA-positive cells was then determined using immunohistochemical cell-specific markers. Eighty-two percent of primary specimens and 74% of restenotic specimens had no evidence of PCNA labeling. The majority of the remaining specimens had only a modest number of PCNA-positive cells per slide (typically < 50 cells per slide). In the restenotic specimens, PCNA labeling was detected over a wide time interval after the initial procedure (eg, 1 to 390 days), with no obvious proliferative peak. Cell-specific immunohistochemical markers identified primary and restenotic PCNA-positive cells as smooth muscle cells, macrophages, and endothelial cells. In conclusion, the findings were as follows: (1) Proliferation in primary and restenotic coronary atherectomy specimens, as indicated by PCNA labeling, occurs infrequently and at low levels. (2) The response to injury in existing animal models of angioplasty may follow a very different course of events from the clinical reality in human atherosclerotic coronary arteries and may help explain why current approaches to restenosis therapy have been ineffective.

Adult↗
PubMed1993

Directional coronary atherectomy complications and management.

Directional coronary atherectomy provides a predictable outcome in selected cases; however, DCA may still result in significant complications in a small number of patients. Although many of the complications are similar to those associated with PTCA, some of the complications are unique or more frequently observed with DCA. These complications are often preventable with adequate case selection and appropriate technique. Because of significant differences in the atherectomy procedure compared to PTCA, the operator should recognize and understand the technical differences to prevent potentially serious complications.

Atherectomy, Coronary↗
PubMed1992

Influence of vessel selection on the observed restenosis rate after endoluminal stenting or directional atherectomy.

In comparing the restenosis rates among different interventions, 1 potential confounder might be the differences in the vessels treated, as dictated by the technical limitations of particular devices. The purpose of this study was to use current "acute gain-late loss" analysis to examine what influence vessel selection has on the restenosis rates seen after coronary stenting or directional atherectomy. The minimal luminal diameter of native coronary lesions was measured before and immediately after intervention in 102 single Palmaz-Schatz stents and 347 atherectomies, 367 (82%) of which had repeat angiographic measurement 6 months after intervention. Atherectomy-treated lesions had a higher proportion of left anterior descending to right coronary arteries (68 vs 24%) compared with stents (31 vs 54%), p < 0.001. Although subsequent restenosis rates were similar for stenting (25%) and atherectomy (30%, p = 0.42), left anterior descending versus right coronary lesions had a significantly higher restenosis rate for the overall group (35 vs 18%, p = 0.009), for stents (44 vs 13%, p = 0.008) and for atherectomy (35 vs 22%, p = 0.10), respectively. Multivariable analysis demonstrated that postprocedure luminal diameter (p = 0.03, p = 0.009) and coronary location (the proportion of left anterior descending vessels treated, p = 0.002, p < 0.001), but not device type (stent vs atherectomy), were strong independent determinants of restenosis according to both binary (> 50% diameter stenosis) and continuous (late percent stenosis) definitions.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Restenosis after directional coronary atherectomy.

OBJECTIVES: This study evaluates the incidence of restenosis after successful directional coronary atherectomy and identifies risk factors for restenosis. BACKGROUND: Directional coronary atherectomy has been shown to be a safe and effective treatment of obstructive coronary artery disease; however, information regarding restenosis is limited. METHODS: Between October 1986 and December 1989, 289 patients with 332 lesions were successfully treated with directional coronary atherectomy and followed up prospectively. Clinical follow-up information was available for 98% and angiographic follow-up information was obtained for 82% at approximately 6 months, or earlier if symptoms recurred. Angiograms were quantitatively analyzed. Restenosis was defined as greater than 50% stenosis at the site of intervention. RESULTS: Seventy-four percent of patients were either asymptomatic or clinically improved after the procedure. Thirty-two percent were subsequently treated by coronary artery bypass surgery (14%), percutaneous transluminal coronary angioplasty (4%) or repeat atherectomy (13%). Angiographic evidence of restenosis was observed in 42%. The restenosis rate in native coronary arteries was 31% for primary lesions and 28% and 49%, respectively, for lesions treated with one or two previous angioplasty procedures. The restenosis rate for saphenous vein grafts was 53% for primary lesions and 58% and 82%, respectively, for lesions treated with one or two previous angioplasty procedures. The median interval to angiographically documented restenosis was 133 days. A higher restenosis rate was associated with a saphenous vein graft, hypertension, a longer lesion (greater than or equal to 10 mm), a smaller vessel diameter (less than 3 mm), a noncalcified lesion and use of a smaller (6F) device. CONCLUSIONS: Restenosis remains a limitation of directional coronary atherectomy. A subset of patients with larger vessels, shorter lesions or lesions treated with a larger (7F) device may have a more favorable outcome.

Aged↗
PubMed1992

Restenosis after directional coronary atherectomy. Effects of luminal diameter and deep wall excision.

BACKGROUND: Deep wall excision during directional atherectomy has been reported in one study to increase the risk of subsequent restenosis. On the other hand, we have observed that the probability of late (6-month) restenosis is reduced by maximizing postprocedure luminal diameter. Although such maximal luminal enlargement by directional atherectomy has not increased procedural complications in our experience, it might well increase the incidence of subintimal (deep wall component) recovery. We performed this study to evaluate the relative influences of luminal enlargement and deep wall component excision on postatherectomy restenosis. METHODS AND RESULTS: Atherectomy resulted in a 7 +/- 15% residual stenosis with < 0.5% incidence of angiographic vessel perforation. The minimal luminal diameter of each lesion was measured before and after intervention in 413 lesions, 389 (94%) of which had histological analysis of the excised specimens. Specimens were categorized by the deepest layer retrieved: type I (recovery of intima alone, n = 141), type II (recovery of media, n = 79), and type III (recovery of adventitia, n = 65). Repeat angiographic measurement of minimal luminal diameter was available for 329 (80%) segments 6 months after atherectomy. Compared with the 32% restenosis rate for type I excision, there was no increase in restenosis (stenosis > 50%) for type II, type III, or types II+III (p = 0.86). Stratification by vessel characteristics also failed to show any association between restenosis and deep wall component recovery in any subgroup, including native coronary (p = 0.85), left anterior descending coronary artery (p = 0.70), right coronary artery (p = 0.51), saphenous graft (p = 0.78), or prior restenosis lesions (p = 0.98). Paradoxically, the recovery of adventitia (type III excision) was associated with a lower late percent stenosis (p = 0.03) and a trend toward less restenosis (p = 0.11) compared with type I excisions. A multiple logistic regression model was constructed that demonstrated immediate postprocedure luminal diameter (p = 0.02) to be an independent determinant of restenosis. In this model, the presence of deep wall components (type II+III) did not adversely affect (p = 0.86) restenosis, but the recovery of adventitia was associated with an independent trend toward reduced restenosis (p = 0.06). CONCLUSIONS: The immediate goal of directional atherectomy should be to safely provide the largest lumen possible in order to reduce restenosis. The recovery of deep wall components does not appear to jeopardize the beneficial effect that obtaining a large immediate postprocedure lumen diameter has on reducing the incidence of late restenosis.

Atherectomy, Coronary↗
PubMed1991

Effect of lesion characteristics on outcome of directional coronary atherectomy.

Directional coronary atherectomy, a new transluminal procedure for treatment of obstructive lesions in coronary arteries by excision and removal of tissue, was performed on 447 lesions in 382 procedures. Successful outcome, defined as a reduction of stenosis by greater than or equal to 20% with a less than 50% residual stenosis, was achieved in 89.5% of lesions and mean stenosis was reduced from 75.9 +/- 13.3% to 14.5 +/- 22.1% (p less than 0.001). Complications included vessel occlusion during the procedure, 2.4%; vessel occlusion after the procedure, 1.3%; new lesion, 0.5%; nonobstructive guiding catheter-induced dissection, 0.3%; perforation, 0.8%; distal embolization, 2.1%; Q wave myocardial infarction, 0.8% and non-Q wave myocardial infarction, 4.2%. Twelve patients (3.1%) required coronary artery bypass surgery for these complications. The atherectomy success rate was greater than 80% and the combined atherectomy and angioplasty success rate was greater than 90% for complex morphologic features such as eccentric lesions, lengthy lesions, lesions with abnormal contour, angulated lesions, ostial lesions and lesions with branch involvement. In the presence of calcific deposition, atherectomy success rate was 52% for primary lesions and 83% for restenosed lesions. Among angiographically complex lesions, calcium was the predictor for failed atherectomy (p less than 0.0001). In summary, directional coronary atherectomy is safe and effective for treatment of obstructive lesions in coronary arteries in selected cases. In particular, it achieves a high success rate in lesions with complex morphologic characteristics, such as eccentricity, abnormal contour and ostial involvement.

Adult↗
PubMed1991

[Current status of directional coronary atherectomy in interventional cardiology].

Directional coronary atherectomy (DCA) was used in 74 patients with an average age of 56 years. They were categorized into three different groups depending on the indications for atherectomy. Group I included all patients who had atherectomy as their primary intervention (n = 26), because they were assumed to be unsuitable for PTCA. Group II consisted of patients in whom DCA was used after failed balloon dilatation with unsuccessful but uneventful treatment (n = 20). Group III (n = 28) included cases where DCA was performed as a "rescue" or "bail-out" procedure after failed PTCA resulted in critical ischemia (ECG changes, chest pain, hypotension, and shock). The target lesions were located in LM 2, LAD 52, RCA 16, ACVB 4. The mean length of lesion was 8 mm (2-25 mm). The overall success rate was 94%. The mean stenosis was reduced from 90.6 +/- 10% to 17.2 +/- 14.8% in cases with primary success. The presently available follow-up angiography (n = 31) showed six restenoses. Major complications occurred in seven cases (death: 0, myocardial infarction: 2, CABG within 24 h: 5). Histological analysis revealed highly cellular areal as a major characteristics of a coronary lesion and also of restenotic tissue. Tissue of the lamina elastica was present in 44% and of media in 14%. Thrombus was found only rarely. Ultrastructure showed a significant amount of extracellular matrix in the primary coronary lesions and isolated smooth muscle cells without gap-junctions. RER, mitochondria were typical for the synthesizing type of smooth muscle cell. In restenotic tissue a focal high density of smooth muscle cells with increased synthesizing activity and gap-junctions was present. Endothelial cells (and macrophages) were found only rarely. Furthermore, altered smooth muscle cells from restenotic tissue showed a significantly increased migration and proliferation. Our results show that DCA is a safe and effective technique that can extend the use of percutaneous procedures and provide a promising, nonsurgical option in cases of failed PTCA. Histological analysis revealed a proliferative process as a characteristics of restenosis development.

Angioplasty, Balloon, Coronary↗
PubMed1990

Comparison of dissection rates and angiographic results following directional coronary atherectomy and coronary angioplasty.

Directional coronary atherectomy is a new percutaneous transluminal technique for treating occlusive coronary artery disease. In this study, angiographic results (i.e., residual stenosis and angiographic evidence of postprocedure dissection) after directional coronary atherectomy and balloon angioplasty were compared. The atherectomy group consisted of 91 lesions in 83 consecutive patients who underwent either left anterior descending artery or right coronary artery atherectomy. The angioplasty group consisted of 91 lesions in 84 patients that were matched with the atherectomy lesions with respect to vessel and whether the lesion was a restenosis lesion. The mean preprocedure diameter stenosis was 76% in both groups as measured quantitatively with electronic calipers. After the procedure, the mean residual diameter stenosis of the atherectomy lesions was 13 +/- 17%, whereas for the angioplasty lesions it was 31 +/- 18% (p less than 0.001). Success rates in both groups were similar (94.5 and 93.4%, respectively). The incidence of postprocedure dissection was 11% in the atherectomy group and 37% in the angioplasty group (p less than 0.0001). Directional coronary atherectomy results in significantly improved postprocedure angiographic appearances due to significantly less severe residual stenosis and lower incidence of dissection.

Angioplasty, Balloon, Coronary↗
PubMed1990

Primary peripheral arterial stenoses and restenoses excised by transluminal atherectomy: a histopathologic study.

Atherectomy is a new therapeutic intervention for the treatment of peripheral arterial disease, and permits the controlled excision and retrieval of portions of stenosing lesions. The gross and light microscopic features of 218 peripheral arterial stenoses resected from 100 patients by atherectomy were studied. One hundred seventy of these lesions were primary stenoses and 48 were restenoses subsequent to prior angioplasty or atherectomy. Microscopically, primary stenoses were composed of atherosclerotic plaque (150 lesions), fibrous intimal thickening (15 lesions) or thrombus alone (5 lesions). Atherosclerotic plaques had a variable morphology and, in one-third of cases, were accompanied by abundant surface thrombus that probably added to the severity of stenosis. Most patients with fibrous intimal thickening or thrombus alone had typical atherosclerotic plaque removed elsewhere from within the same artery. Intimal hyperplasia, with or without underlying residual plaque, was found at 36 sites of restenosis, the remaining 12 consisting of plaque only. Intimal hyperplasia had a distinctive histologic appearance and was due to smooth muscle cell proliferation within a loosely fibrous stroma. Superimposed thrombus may have contributed to arterial narrowing in 25% of hyperplastic and 8% of atherosclerotic restenoses (p = 0.41). Pathologic examination of tissues recovered by peripheral atherectomy is an important adjunct that may provide insight into the efficacy of vascular interventions and the phenomenon of postintervention restenosis.

Adult↗
PubMed1990

Subfornical organ participates in salt appetite.

The effects of subfornical organ (SFO) lesions on salt and water intakes after sodium depletion were studied. Water and salt intakes were measured over 45 hr during a regimen that combined furosemide diuresis and access to low-sodium diet. Water was solely available for 23 hr after diuresis, and water and 0.3 M NaCl solution were available in choice for the next 22 hr. After diuresis, rats with SFO lesions drank significantly less water in 2 hr than controls but achieved equivalent water and sodium balances before salt access 20 hr later. After salt access, rats with SFO lesions drank significantly less saline and water in 2 hr than controls but had similar saline and water intakes over the next 20 hr. Thus, SFO lesions blunted acutely, but not chronically, saline and water intakes to sodium depletion, and the blunted intakes are not explainable by hydrational status.

Animals↗
PubMed1989

Angiotensin-converting enzyme in subfornical organ mediates captopril-induced drinking.

These experiments tested whether angiotensin-converting enzyme (ACE) located within the subfornical organ (SFO) participates in the generation of water intake during peripheral ACE blockade with captopril (CAP). Lesions of the SFO virtually abolished drinking in response to intraperitoneal CAP injection. Intracranially injected CAP suppressed drinking induced by intraperitoneal CAP more completely with direct SFO injection compared with intraventricular or control tissue injections. This central captopril treatment did not alter the drinking response to subcutaneous hypertonic saline. Intraventricular injections of the angiotensin II (ANG II) receptor blocker sarile reduced drinking during oral captopril treatment in rats rehydrating from water deprivation. The results indicate that (a) the SFO mediates drinking caused by peripheral ACE inhibition; (b) the ACE located within the SFO may locally convert ANG I to ANG II, which then stimulates thirst; and (c) central ANG II receptors mediate thirst caused by peripheral ACE inhibition.

Animals↗
PubMed1988

Transluminal atherectomy for occlusive peripheral vascular disease.

Sixty-one patients with occlusive peripheral vascular disease were treated with transluminal atherectomy, a catheter-mediated technique for removal of atheroma. The technique was performed using 7Fr, 9Fr or 11Fr atherectomy catheters. Mean percent diameter stenosis was reduced from 71 to 23%, by removal of 831 atheromatous specimens in 949 passes of the cutting element through 136 stenoses in 61 patients. All specimens removed were sent for histopathologic examination to determine the components of the atheroma removed, which differed for specimens removed from original vs restenotic lesions. Percent stenosis was reduced to less than 45% in 118 of 136 stenoses (87%). Complications included 1 thrombus, which resolved after intraarterial infusion of streptokinase and 1 probable distal embolization without sequelae. Three angiographic dissections occurred without impairment of blood flow. There were no instances of acute occlusion, vascular spasm or vessel perforation. Six-month follow-up angiography was performed showing that patients who had a residual stenosis less than 30% after initial atherectomy had a lower restenosis rate (18%) than patients with initial residual stenoses greater than 30% (52%); this result demonstrated the importance of performing more complete atherectomy. Transluminal atherectomy appears to be an effective, predictable and safe method for removing occlusive atheromatous deposits from peripheral arteries.

Angioplasty, Balloon↗
PubMed1988

Percutaneous removal of atheromatous plaques in peripheral arteries.

The peripheral Simpson "atherectomy" catheter was used to treat 21 patients with a total of 41 stenotic lesions (5 iliac, 35 superficial femoral, and 1 popliteal). 4 lesions were totally occluded and 16 (39%) were calcified. The mean (SD) degree of obstruction was reduced from 82.7 (14) to 21 (16)% (p less than 0.0001). Mean (SD) standardised walking distance increased from 79.9 (71.9) to 152.6 (89.7) m (p less than 0.0001); doppler index improved from 0.58 (SD 0.17) to 0.81 (0.16) (p less than 0.0001); performance on bicycle stress test rose from 276.3 (range 1-1100) to 584.8 (2-2250) watt-min; and index for 201Tl-scintigraphy of the lower leg increased from 0.68 (0.28) to 0.91 (0.36) (p less than 0.02). The improvement has been maintained for 6 months, the degree of stenosis on repeat angiography at 2-6 months (n = 14 lesions) being 20.7 (SD 13.7)% (unchanged from early post-treatment values). The only restenosis has been corrected by a repeat of the percutaneous procedure.

Aged↗
PubMed1988

Transluminal intracoronary reperfusion catheter: a device to maintain coronary perfusion between failed coronary angioplasty and emergency coronary bypass surgery.

The reperfusion catheter is a 4.3F catheter with 30 holes over its distal 10 cm. It is used to maintain coronary blood flow in patients awaiting emergency coronary bypass surgery after failed coronary angioplasty. The insertion of the reperfusion catheter was attempted in 20 patients (14 with total occlusion and 6 with severe residual stenosis judged to be in jeopardy of reclosure before operation). The reperfusion catheter was successfully placed across the obstruction in 18 patients (90%). After successful insertion of the reperfusion catheter, 16 patients had good anterograde flow (Thrombolysis in Myocardial Infaction [TIMI] trial grade II or III); angiographic improvement was associated with significant lessening of ST segment elevation as well as a decrease in chest pain in most patients. Two patients had poor or absent anterograde flow (TIMI grade O or I) because of extensive preexisting intracoronary thrombosis; one died from refractory ventricular fibrillation. In each of the remaining patients emergency coronary bypass surgery was performed with no deaths or significant cardiac complications. The reperfusion catheter is a safe and effective method to reestablish and maintain coronary blood flow before coronary bypass surgery after failed coronary angioplasty. Because there is the potential risk of serious complications, particularly thrombus formation within this catheter, the reperfusion catheter should be used cautiously and the patient should undergo immediate bypass surgery.

Angioplasty, Balloon↗