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R S Stack

Publications and source records attributed to R S Stack.

At least 37 records · Page 2Linked to original sources
PubMed1995

Intravascular ultrasound in the management of acute coronary artery dissection: a case report.

Crossing total occlusions is frequently difficult. The guidewire may enter a false lumen, thereby preventing successful balloon dilatations. We present a case of an acute arterial dissection following attempted angioplasty of a totally occluded right coronary artery. With an intravascular ultrasound probe in the false lumen, we were able to visualize a second guidewire and direct its passage into the true arterial lumen. This allowed for successful balloon dilatation and stent deployment restoring vessel patency.

Aortic Dissection↗
PubMed1995

Percutaneous revascularization of chronic coronary occlusions: an overview.

Patients with a chronic coronary occlusion often undergo coronary angiography after weeks to months of occlusion. The published reports underestimate the extent of this problem because such patients are often arbitrarily assigned to receive medical therapy or undergo bypass surgery as a result of poor success with percutaneous revascularization and substantial restenosis. Thus, there is controversy about the role of angioplasty in this patient cohort. The goal of this overview was to evaluate the available information about angioplasty in chronic coronary occlusions. The primary indication for attempted recanalization of a chronic coronary occlusion has been symptomatic angina pectoris. Anginal status often improves after successful procedures (70% vs. 31% with a failed procedure); left ventricular function may improve; and subsequent referral for coronary artery bypass graft surgery is uncommon (3% vs. 28% in unsuccessful cases). Successful recanalization is achieved in approximately 65% of attempted procedures. Inability to cross the stenosis with a guide wire is the most common cause of procedural failure. Statistically significant predictors of procedural success include older occlusions (75% < 3 months old vs. 37% > or = 3 months old), absence of any anterograde flow through the occlusion (76% with vs. 58% without), angiographically abrupt-appearing occlusions (50% vs. 77% with tapered occlusions), presence of bridging collateral vessels (23% with vs. 71% without) and lesions > 15 mm. Procedural complications occur at a slightly lower incidence than in angioplasty of high grade subtotal stenoses. Long-term success is limited, and restenosis can be expected in > 50% of the patients. The experience with chronic total occlusions of saphenous vein bypass grafts is small, but there appear to be limited procedural success and significant procedural complications, particularly associated with distal emboli. The role of new pharmacologic agents has yet to be defined and that of new devices has been disappointing so far, but further technologic advances are on the horizon.

Angioplasty, Balloon, Coronary↗
PubMed1995

Lymph node metastasis from carcinoma in situ of the penis: a case report.

Lymph node metastasis from carcinoma in situ of the penis is rare. We report a case of carcinoma in situ of the penis that was initially managed with circumcision and topical 5-fluorouracil. Subsequently inguinal and para-aortic lymph node metastasis developed, which was treated successfully with systemic chemotherapy and right inguinal lymph node dissection. The patient is free of disease 7 years after initial diagnosis and 3 years after the diagnosis of nodal metastasis.

Carcinoma in Situ↗
PubMed1995

The role of the perfusion balloon catheter after an initially unsuccessful coronary intervention.

Major dissection and acute closure following conventional percutaneous transluminal coronary angioplasty (PTCA) occur in 5%-10% of cases and lead to significant morbidity. Newer percutaneous modalities such as directional coronary atherectomy (DCA), excimer laser coronary angioplasty (ELCA), rotational ablation, and transluminal extraction atherectomy (TEC) can also be complicated by dissection and acute closure. Redilatation with conventional balloon catheters can reestablish patency of the artery or improve flow in a minority of cases. The perfusion balloon catheter (PBC) has several advantages over conventional balloon angioplasty in this situation. In approximately 70% of these cases, subsequent use of a PBC yields an acceptable clinical and angiographic result. The PBC permits rapid resolution of ischemia caused by acute closure or a flow-limiting dissection. New modifications of the PBC make it possible to position the catheter in nearly all segments of the coronary arterial tree including locations not accessible to other modalities, such as coronary stents or DCA, that are also used for salvage after a failed coronary intervention. Even if the PBC does not yield a definitive result, it allows rapid restoration of antegrade flow prior to coronary artery bypass grafting or coronary stent placement. Because of its ease of use, wide applicability, and efficacy, the PBC should be considered as the initial means of treatment in cases of major dissection or acute closure following any modality of percutaneous coronary revascularization.

Angioplasty, Balloon, Coronary↗
PubMed1994

Testicular cancer in blacks. A multicenter experience.

BACKGROUND: The rarity of testis tumor in black patients has made the study of a large series difficult. Much of the epidemiologic and clinical information regarding this neoplasm in this population is in dispute, including data on incidence, prognosis, histologic distribution, age and stage at presentation, and side distribution. METHODS: A retrospective review of 66 blacks with testicular tumors from seven military medical centers was performed. RESULTS: Similar results were found for blacks with testis tumor to those of the general testis cancer population regarding prognosis, side distribution, and age of onset for nonseminoma and interstitial tumors. There is a slight increase in the expected number of interstitial tumors in blacks, but the distribution between seminoma and nonseminoma is similar to the general population. The mean age of presentation for seminoma in blacks was younger than that of the general testis cancer population. For testis tumor treated at the same institution, there was an increased delay of diagnosis in blacks compared with whites. The number of new cases of testicular cancer between 1979 and 1991 at one major center was increased for whites but not for blacks. The availability of cisplatin-based combination chemotherapy has resulted in an improved prognosis for blacks, as has already been demonstrated for white populations. CONCLUSIONS: Testis tumor in blacks behaves similarly to testis tumor in the general population except that in blacks there are more interstitial tumors and the mean age of presentation for seminoma is younger. Further, there is an increased delay in diagnosis for blacks compared with whites, but the incidence of this tumor in this population does not appear to be increasing. Cisplatin-based chemotherapy has significantly improved survival in this population.

Adult↗
PubMed1994

Effects of coronary angioplasty, coronary bypass surgery, and medical therapy on employment in patients with coronary artery disease. A prospective comparison study.

OBJECTIVE: To compare return-to-work rates after coronary angioplasty, coronary bypass surgery, and medical therapy in patients with coronary disease. DESIGN: Prospective cohort study. SETTING: Tertiary care referral center. PATIENTS: Between March 1986 and June 1990, we enrolled 1252 patients who were younger than 65 years, who had not had previous coronary revascularization, and who were employed. All patients were followed for 1 year. MAIN OUTCOME MEASURE: One-year employment status. RESULTS: After 1 year, 84% of patients who had coronary angioplasty were still working compared with 79% of patients who had bypass surgery and with 76% of patients who received medicine. After adjusting for the more favorable baseline characteristics of patients who had angioplasty (less severe coronary artery disease, better left ventricular function, and less functional impairment), however, no significant differences were noted in 1-year employment rates among the three groups. These adjusted 1-year return-to-work rates were 84% for angioplasty, 80% for surgery, and 79% for medicine (P > 0.05). In a random subset of 72 patients, 23 patients who had angioplasty returned to work after a median of 18 days (mean, 27 days) compared with 54 days (mean, 67 days) for 24 patients having bypass surgery and with 14 days (mean, 45 days) for 25 patients receiving medicine (P = 0.002). CONCLUSIONS: Patients who had coronary angioplasty were able to return to work earlier than those who had bypass surgery, but by 1 year no significant difference was noted in employment rates. Neither revascularization strategy improved employment rates when compared with initial treatment using medical therapy.

Angioplasty, Balloon, Coronary↗
PubMed1994

Continuing evolution of therapy for coronary artery disease. Initial results from the era of coronary angioplasty.

BACKGROUND: Survival after coronary artery bypass graft surgery (CABG) and medical therapy in patients with coronary artery disease (CAD) has been studied in both randomized trials and observational treatment comparisons. Over the past decade, the use of coronary angioplasty (PTCA) has increased dramatically, without guidance from either randomized trials or prospective observational comparisons. The purpose of this study was to describe the survival experience of a large prospective cohort of CAD patients treated with medicine, PTCA, or CABG. METHODS AND RESULTS: The study was designed as a prospective nonrandomized treatment comparison in the setting of an academic medical center (tertiary care). Subjects were 9263 patients with symptomatic CAD referred for cardiac catheterization (1984 through 1990). Patients with prior PTCA or CABG, valvular or congenital disease, nonischemic cardiomyopathy, or significant (> or = 75%) left main disease were excluded. Baseline clinical, laboratory, and catheterization data were collected prospectively in the Duke Cardiovascular Disease Databank. All patients were contacted at 6 months, 1 year, and annually thereafter (follow-up 97% complete). Cardiovascular death was the primary end point. Of this cohort, 2788 patients were treated with PTCA (2626 within 60 days) and 3422 with CABG (3080 within 60 days). Repeat or crossover revascularization procedures were counted as part of the initial treatment strategy. Kaplan-Meier survival curves (both unadjusted and adjusted for all known imbalances in baseline prognostic factors) were used to examine absolute survival differences, and treatment pair hazard ratios from the Cox model were used to summarize average relative survival benefits. For the latter, a 13-level CAD prognostic index was used to examine the relation between survival and revascularization as a function of CAD severity. The effects of revascularization on survival depended on the extent of CAD. For the least severe forms of CAD (ie, one-vessel disease), there were no survival advantages out to 5 years for revascularization over medical therapy. For intermediate levels of CAD (ie, two-vessel disease), revascularization was associated with higher survival rates than medical therapy. For less severe forms of two-vessel disease, PTCA had a small advantage over CABG, whereas for the most severe form of two-vessel disease (with a critical lesion of the proximal left anterior descending artery), CABG was superior. For the most severe forms of CAD (ie, three-vessel disease), CABG provided a consistent survival advantage over medicine. PTCA appeared prognostically equivalent to medicine in these patients, but the number of PTCA patients in this subgroup was low. CONCLUSIONS: In this first large-scale, prospective observational treatment comparison of PTCA, CABG, and medicine, we confirmed the previously reported survival advantages for CABG over medical therapy for three-vessel disease and severe two-vessel disease. For less severe CAD, the primary treatment choices are between medicine and PTCA. In these patients, there is a trend for a relative survival advantage with PTCA, although absolute survival differences were modest. In this setting, treatment decisions should be based not only on survival differences but also on symptom relief, quality of life outcomes, and patient preferences.

Angioplasty, Balloon, Coronary↗
PubMed1994

Rapid visualization of massive pulmonary emboli utilizing intravascular ultrasound.

Massive pulmonary embolism may result in rapid deterioration prior to diagnostic and therapeutic intervention. Intravascular ultrasound imaging has been utilized previously to evaluate vascular abnormalities as well as normal human pulmonary arteries. We employed this technique to rapidly identify massive pulmonary emboli located in the main pulmonary arteries of two patients. The presence of these emboli was confirmed with pulmonary arteriography. Intravascular ultrasound may be utilized to rapidly confirm the presence of large proximal pulmonary emboli.

Aged↗
PubMed1994

Pharmacomechanical thrombolysis of experimental pulmonary emboli. Rapid low-dose intraembolic therapy.

We utilized low-dose intraembolic urokinase (UK) infusions in a canine model of experimental pulmonary embolism (PE) and compared the arteriographic extent of thrombolysis with three other treatment regimens. Group 1 animals (n = 16) received the intraembolic UK infused directly into the PE offering the mechanical effect of the infusion combined with pharmacologic thrombolysis. In the group 2 animals (n = 5), UK was delivered via a guide catheter placed proximal to the clot. Group 3 animals (n = 6) were treated with a direct intraembolic saline solution infusion. Group 4 (n = 7) received only intravenous heparin. The arteriographic extent of thrombolysis was graded 1+ to 3+. The extent of thrombolysis was 2.88+ in the group 1 animals and was significantly greater than in groups 2, 3, or 4 (p = 0.003, 0.0005, and 0.0001, respectively). Fibrinogen levels did not significantly decrease with intraembolic treatment (p = 0.07). Delivery of UK directly into emboli in an experimental canine PE model appears to elicit a combined mechanical and pharmacologic effect resulting in extensive thrombolysis.

Animals↗
PubMed1994

Transluminal extraction coronary atherectomy.

The TEC is a forward-cutting atherectomy catheter that has the unique potential to excise and aspirate atheroma, especially intraluminal thrombus. This device has been under clinical investigation for more than 6 years and received final marketing approval by the FDA for the treatment of lesions in the coronary vasculature in 1993. In the US TEC Multicenter Registry, the overall clinical and lesion successes were favorable. The success rates were similar for both native coronary vessels and saphenous vein bypass grafts. Importantly, the procedural success rates were maintained even in the presence of several unfavorable angiographic features, such as ostial location, intraluminal thrombus, and total occlusion. Further insights into the mechanisms of action of the TEC were made from studies using percutaneous angioscopy and intravascular ultrasound. Angioscopy clearly demonstrated that the TEC was indeed able to remove intraluminal thrombus, especially loosely adherent red thrombus, in a population of patients with unstable coronary syndromes. However, the TEC frequently leaves behind multiple intimal disruptions which not only create a possible nidus for restenosis but also explain the frequent hazy angiographic appearance of the vessel after TEC atherectomy. As is true for all new interventional devices, the specific niche for the TEC in interventional cardiology will best be determined in randomized clinical trials. There are several areas in which the TEC appears promising. First, this device may have a role in the management of patients with diffusely diseased saphenous vein grafts. Second, the TEC may be an effective primary therapy in lesions with intraluminal thrombus. Treatment with the TEC may then be followed by an adjunctive therapy to maximize the final vessel diameters. Finally, the TEC may be valuable in the treatment of lesions in patients with high-risk unstable coronary syndromes.

Atherectomy, Coronary↗
PubMed1994

Current status of biodegradable stents.

Coronary angioplasty remains limited by abrupt closure and restenosis. Metallic stents are useful for suboptimal PTCA results or threatened closure and can reduce restenosis in de novo lesions. However, they are permanent devices that are used to treat a short-term problem and have only limited potential for local drug delivery. Several catheters have been designed for specific delivery of drugs or gene products. Unfortunately drug delivery efficiency and long-term retention remain problematic. To overcome these limitations and provide a scaffold for the remodeling vessel as well as a vehicle for sustained local drug delivery, bioabsorbed stents have been proposed as an alternative. This article describes the limitations of the current metallic stents, reviews the initial animal studies of polymeric stents, and proposes the biodegradable stent as a local drug delivery device to prevent restenosis and acute closure post-PTCA.

Angioplasty, Balloon, Coronary↗
PubMed1993

Long-term outcome following successful reopening of abrupt closure after coronary angioplasty.

Abrupt closure after coronary angioplasty is often successfully treated by repeat dilation. Long-term follow-up, including 6-month repeat catheterization and 12-month clinical evaluation, was obtained in 1,056 patients treated with acute (n = 335) or elective (n = 721) coronary angioplasty to evaluate the long-term impact of successful reopening of abrupt closure. Abrupt closure occurred in 13.5% of patients and was successfully reopened in 58%. Adverse outcomes including restenosis, death, bypass surgery, myocardial infarction and repeat angioplasty were compared between patients with successfully treated abrupt closure and those with successful procedures (residual diameter stenosis < or = 50%) without abrupt closure. For patients with acute angioplasty, the restenosis rates (> 50% diameter stenosis at follow-up) were 64% for those with successfully treated abrupt closure versus 36% for those with successful procedures without abrupt closure (p < 0.01). In addition, subsequent myocardial infarction (12 vs 3%; p = 0.01) and repeat angioplasty (21 vs 10%; p = 0.03) were more frequent in the group with abrupt closure. For patients with elective angioplasty, restenosis was 43% in those with successfully treated abrupt closure versus 45% in those without abrupt closure (p = NS). Subsequent death and myocardial infarction were more frequent in patients with abrupt closure (death: 12 vs 3% [p < 0.01]; myocardial infarction: 13 vs 3% [p < 0.01]). Long-term adverse events are increased in patients with successfully treated abrupt closure compared to those with successful procedures without abrupt closure.

Acute Disease↗
PubMed1993

Treatment of long coronary artery narrowings with long angioplasty balloon catheters.

Balloon angioplasty of long coronary artery narrowings has been associated with a lower rate of acute success, and a higher rate of acute complications and restenosis than that observed for short narrowings. Angioplasty catheters with longer length balloons (30 and 40 mm) are now available, and the objective of this study was to determine the acute and long-term success for patients with long coronary artery narrowings treated with these longer balloons. All patients with long narrowings (> or = 10 mm) treated with long balloons at 1 institution over a 1-year period were identified (93 narrowings in 89 patients), and acute and long-term outcomes were carefully documented. Procedural success (residual stenosis < or = 50%) was 97%. Abrupt closure occurred in 6% and major dissection in 11% of narrowings. Clinical success (procedural success without in-hospital death, bypass surgery or myocardial infarction) was achieved in 90% of patients. Repeat catheterization was performed in 61 patients (76% of those eligible), and restenosis was found in 50 to 55%, depending on the definition used. The treatment of long coronary artery narrowings using angioplasty catheters with longer balloons leads to high rates of acute success. However, there is a high rate of restenosis. New interventional devices for long lesions should be compared with long balloons in a randomized controlled trial.

Aged↗
PubMed1993

In vivo validation of compensatory enlargement of atherosclerotic coronary arteries.

Necropsy examinations and epicardial ultrasound studies have suggested that atherosclerotic coronary arteries undergo compensatory enlargement. This increase in vessel size may be an important mechanism for maintaining myocardial blood flow. It also is of fundamental importance in the angiographic study of coronary disease progression and regression. The purpose of this study was to determine, using intracoronary ultrasound, whether coronary arteries undergo adaptive expansion in vivo. Forty-four consecutive patients were studied (30 men, 14 women; mean age 56 +/- 10 years). Eighty intravascular ultrasound images were analyzed (32 left main, 23 left anterior descending and 25 right coronary arteries). Internal elastic lamina area, a measure of overall vessel size increased as plaque area expanded (r = 0.57, p = 0.0001, SEE = 5.5 mm2). When the left main, left anterior descending and right coronary arteries were examined individually, there continued to be as great or greater positive correlation between internal elastic lamina and plaque area (left anterior descending: r = 0.75, p = 0.0001; right coronary arteries: r = 0.63, p = 0.0007; left main: r = 0.56, p = 0.0009), implying that each of the vessels and all in aggregate underwent adaptive enlargement. When only those vessels with < 30% area stenosis were examined, internal elastic lamina correlated well with plaque area (r = 0.79, and p = 0.0001), and for each 1 mm2 increase in plaque area, internal elastic lamina increased 2.7 mm2. This suggests that arterial enlargement may overcompensate for early atherosclerotic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1993

Lack of impact of early catheterization and fibrin specificity on bleeding complications after thrombolytic therapy. The TAMI Study Group.

OBJECTIVES: The aim of this study was to assess the hemorrhagic risk associated with fibrin-specific thrombolytic therapy and invasive procedures with acute myocardial infarction. BACKGROUND: Successful coronary artery reperfusion has important prognostic implications. Because immediate coronary angiography is the only method proved to differentiate early fibrinolytic success from failure, its use may be important for selected patients. METHODS: Five hundred seventy-five patients were evaluated with six combined thrombolytic and catheterization strategies. Patients were randomized to intravenous urokinase alone, recombinant tissue-type plasminogen activator (rt-PA) alone, or both; simultaneously they were randomized to an immediate versus a deferred catheterization strategy. Hemorrhagic events were assessed. The correlation of hemorrhage with clinical and hemostatic variables was evaluated. Prespecified transfusion criteria were employed. RESULTS: No difference in baseline characteristics or in hemorrhagic complications was noted among the three thrombolytic regimens. Although mild (< 250 ml) bleeding was more common in the group with immediate catheterization, no clinically significant difference among catheterization groups was seen in moderate to life-threatening hemorrhagic events. Most bleeding occurred at vascular access sites, yet severe and life-threatening hemorrhage occurred in < 1% of patients. Baseline and nadir fibrinogen levels, change in baseline fibrinogen levels and peak fibrin and fibrinogen degradation products did not correlate with bleeding risk. A clinical predisposition for bleeding was observed in women as well as older (> or = 65 years) and lighter (< or = 70 kg) patients. With prespecified transfusion criteria, only a minimal increase in blood product usage was noted with immediate catheterization. CONCLUSIONS: Immediate cardiac catheterization can be accomplished without a clinically significant difference in bleeding risk. Fibrin specificity offers no clear advantage in reducing hemorrhagic risk. Bleeding risk correlates best with baseline patient characteristics. Finally, the amount of blood transfused can be reduced with lower transfusion criteria.

Cardiac Catheterization↗
PubMed1993

Unrecognized left main coronary artery disease in patients undergoing interventional procedures.

Selective, coronary arteriographic, catheter-based, intravascular ultrasound images were obtained to determine the presence and extent of angiographically undetected or underestimated left main (LM) coronary arterial narrowing in patients receiving coronary interventional therapy. Coronary arteriograms were determined to be either normal or abnormal by visual inspection. Abnormal arteriograms were digitized and quantitated using a semiautomated edge-detection algorithm. Thirty-eight patients receiving percutaneous treatment of stenoses in the left coronary artery system were studied. Optimal LM coronary angiograms were obtained in 2 views, and intravascular ultrasound images were obtained after the coronary interventional procedure. Intravascular ultrasound detected plaque in 24 of 27 angiographically normal LM arteries (89%), whereas narrowing was observed in 11 of 11 angiographically abnormal LM arteries (100%). Eight of 38 patients (21%) had > 40% area stenosis by intravascular ultrasound. In patients with angiographic disease, there was no correlation between quantitative angiographic and ultrasound percent area stenosis (r = 0.12; p = 0.72; SEE 19%). The median plaque area was not different between angiographically normal (0.05 cm2; 0.03, 0.08 [25th, 75th percentile]) and abnormal (0.06 cm2; 0.03, 0.1) patients. The median percent area stenosis in arteriographically normal subjects (26%; 14, 32%) was less than that in abnormal ones (37%; 20, 46%) (p = 0.03). Unrecognized LM disease is widespread and often underestimated in patients with normal LM angiograms undergoing interventional procedures. Plaque area is similar for angiographically normal and insignificantly abnormal vessels. This study suggests that intravascular ultrasound overcomes the limitations of silhouette imaging and can be a clinically useful, adjunctive method to evaluate LM coronary artery disease.

Algorithms↗
PubMed1993

Thermal-perfusion balloon coronary angioplasty: in vivo evaluation.

The goal of this study was to develop and test a new radio frequency thermal balloon system to allow longer balloon inflations at lower temperature levels than have been used with standard (laser) thermal balloon angioplasty. Radio frequency thermal capabilities were combined with perfusion balloon technology, creating a thermal-perfusion balloon catheter system for prolonged thermal inflations. Twenty-five dogs underwent thermal-perfusion angioplasty at 37 degrees, 60 degrees, or 80 degrees C for 1.5, 5, or 15 minutes with angiographic and morphologic assessments at 24 hours (n = 17) or 4-6 weeks later (n = 8). Treated segments and side branches remained patent. No coronary spasm, occlusive thrombus, or ischemic myocardial infarction occurred. Histologic extent of thermal injury in treated segments was proportional to treatment duration. Thus the thermal-perfusion balloon angioplasty system may be safely applied in canine coronary arteries. Integrating thermal and perfusion technologies provides prolonged treatment duration at moderate temperatures without excessive tissue damage.

Anesthesia, General↗