Endovascular beta-irradiation after percutaneous transluminal coronary balloon angioplasty

PURPOSE: Intraluminal beta-irradiation has been shown to markedly decrease fibrointimal proliferation after arterial injury in experimental models. With the aim of reducing the incidence of restenosis after percutaneous transluminal coronary angioplasty (PTCA), we undertook a pilot clinical evaluation to assess both the technical feasibility and the clinical safety of this treatment after balloon coronary angioplasty. METHODS AND MATERIALS: Between June 21 and November 15, 1995, 15 patients (6 women and 9 men, aged 72 +/- 5 years) underwent intracoronary beta-irradiation immediately after a conventional PTCA procedure. Both the PTCA and irradiation procedure were done in a conventional catheterization laboratory, using an endoluminally centered pure metallic 90Y source, a newly developed technique of intracoronary beta-irradiation. This was done after documenting the ability of the system to generate reproducible dose delivery to the arterial wall. RESULTS: Both the PTCA and the irradiation procedure were technically feasible in all attempted cases, and a dose of 18 Gy was delivered with a local exposure time of 391 +/- 206 s (range 153-768). In four patients, the intervention was completed by intraarterial stent implantation because of dissection induced by the initial PTCA. No in-hospital complications occurred, and serial creatine kinase measurements remained within the normal range in all cases. CONCLUSION: Our early experience thus suggests that reliable and reproducible dose delivery can be achieved, and that coronary endoluminally centered beta-brachytherapy is both feasible and safe on a short-term basis in the clinical setting. Whether this novel mode of therapy will favorably influence post-PTCA restenosis in patients, as it does in experimental models, must await long-term angiographic follow-up of the present series as well as further clinical study.     

Prevention and treatment of restenosis after percutaneous transluminal coronary angioplasty

Restenosis is a clinical problem after coronary angioplasty associated with major ischemic events or repeat interventions in 20-50% of the patients undergoing this procedure. Major efforts have been undertaken in the past decade to successfully prevent or treat restenosis but no pharmacologic approach to the problem has as yet been identified to be effective enough in clinical conditions. New strategies to cope with restenosis are targeted by local application of ionizing radiation which markedly reduces cell proliferation after angioplasty in animal experiments. Preliminary clinical trials indicate that endovascular radiation therapy is a safe and effective means to treat restenosis. Randomized, multicenter studies with long follow-up periods are needed to support these early results.     

Pathophysiology of restenosis following percutaneous transluminal coronary angioplasty

Symptomatic restenosis occurs in approximately 30-40% of patients after percutaneous transluminal coronary angioplasty (PTCA). Despite intensive research, the primary pathophysiological mediators have not been defined, and pharmacological therapy has not been effective in preventing restenosis. Restenosis is a multifactorial and sequential process, which is initiated by mechanical injury of the vessel wall, and involves neointima formation caused by the local proliferation of smooth muscle cells and production of an extracellular matrix, followed by vascular remodelling. Numerous mediators are involved in these processes, e.g., protooncogenes, growth factors, cytokines and nitric oxide. This review discusses the pathobiological mechanisms underlying coronary restenosis, and outlines the prospects for future therapy.     

Experimental animal models and complications of transluminal coronary angioplasty

Serial changes in the endometrial levels of estrogen and progesterone receptors (ER and PR) were measured in 50 women from days 2 to 14 of missed menses and correlated with the plasma concentrations of hCG, progesterone and 17 beta-estradiol. Both ER and PR of nuclei were higher than cytosolic proteins, with a shift in the ratio of nER/nPR to nPR from 4th day after missed menses. On Scatchard analysis of the cytosolic and nuclear binding proteins, two classes of proteins, corresponding to Type I and II, were found. While the increasing levels of hCG maintained luteal secretion of progesterone and 17 beta-estradiol at normal mid-luteal phase levels, a gradual increase in 17 beta estradiol from 9th day of missed menses was noted. This delicate balance between circulating levels of progesterone and 17 beta-estradiol and their nuclear receptors at early stages of pregnancy may be of significance.     

Radiofrequency thermal balloon coronary angioplasty: a new device for successful percutaneous transluminal coronary angioplasty

OBJECTIVES: The purpose of this study was to evaluate the effects of thermal balloon percutaneous transluminal coronary angioplasty using radiofrequency energy in the treatment of patients with failed coronary angioplasty and complex lesions. In addition, we evaluated restenosis after radiofrequency thermal balloon applications. BACKGROUND: The efficacy of coronary angioplasty is limited by the relatively low success rate in complex lesions and the high frequency of restenosis. Few reports have studied the combined effects of pressure and laser thermal energy. This study describes a new device for coronary angioplasty using radiofrequency thermal energy. METHODS: Thirty-two patients with failed conventional coronary angioplasty or complex lesions were treated with radiofrequency thermal balloon coronary angioplasty. Radiofrequency energy was delivered up to 11 times in exposures ranging from 30 to 60 s in duration. This combined effect allowed the vascular wall to be heated to temperatures ranging from 60 to 70 degrees C. Follow-up coronary angiography was performed, on average, 6 months after the procedure. RESULTS: Successful radiofrequency coronary angioplasty was achieved in 28 (82%) of 34 lesions. There was one abrupt coronary artery occlusion (3%) and no death, perforation or dissection. Angiographic restenosis occurred in 14 (56%) of 25 lesions. CONCLUSIONS: In patients with failed coronary angioplasty and difficult complex lesions, radiofrequency coronary angioplasty could potentially improve angioplasty success rates and may have important implications for bailout cases with abrupt occlusion. However, restenosis remains a significant problem.     

Anesthesia for abdominal surgery after percutaneous transluminal coronary angioplasty (PTCA)

From December 1989 to October 1996, 1,318 PTCAs (percutaneous transluminal coronaly angioplasty) were performed for AMI (acute myocardial infarction) or postinfarction angina in our institute. Within 7 days to 71 days after successful PTCA, five patients who had been diagnosed as cholelithiasis or gastric cancer were operated under general anesthesia. Performed operations were cholecystectomy in the first patient, subtotal gastrectomy in the second, third and fourth patients, and total gastrectomy and cholecystectomy in the fifth patient. There was no serious cardiac complication during the operations and perioperative period. PTCA is considered to have decreased cardiac complications in patients with ischemic heart disease having undergone abdominal surgery.     

Association of an acute reduction in lipoprotein(a) with coronary artery restenosis after percutaneous transluminal coronary angioplasty

BACKGROUND: Lipoprotein(a) [Lp(a)], which structurally resembles-tissue-type plasminogen, is reported to be associated with coronary atherosclerosis. We examined whether the acute change in Lp(a) by percutaneous transluminal coronary angioplasty (PTCA) is related to restenosis after PTCA. METHODS AND RESULTS: We measured serum Lp(a) and other lipid parameters (triglycerides and total, LDL, and HDL cholesterol) before and 1 day after PTCA in 143 procedures and 3 days after and 4 months after PTCA in 62 procedures. Quantitative coronary angiography was performed, and restenosis was defined according to three criteria: (1) clinical recurrence of ischemic symptoms, (2) a final stenosis > 50%, and (3) an absolute decrease in minimal lumen diameter > 1/2 of the acute gain in the dilated segment. Restenosis was recognized in 25.9%, 35.7%, and 38.5% of the cases 4 months after PTCA for each criterion, respectively. Although triglyceride and LDL, HDL, and total cholesterol levels were similar in the restenosis and no-restenosis groups before PTCA, Lp(a) was significantly higher in the restenosis group. We found a significant reduction in Lp(a) in the restenosis but not the no-restenosis group 1 day after PTCA. At 3 days after and 4 months after PTCA, Lp(a) was similar in the two groups. A multivariate-analysis revealed that the absolute change in Lp(a) (before versus 1 day after PTCA) to be the sole significant predictor of restenosis among the clinical, angiographic, and plasma lipid parameters examined. CONCLUSIONS: Lp(a) levels were significantly higher in the restenosis group, and they fell significantly after PTCA in the restenosis group.     

Restenosis and remodeling after percutaneous transluminal carotid angioplasty

INTRODUCTION: The characteristics of restenosis and remodeling after carotid percutaneous transluminal angioplasty (PTA) were badly known. OBJECTIVE: To describe these characteristics in our series of carotid PTA. PATIENTS AND METHODS: A total of 78 cases of PTA for symptomatic > 70% atherosclerotic stenosis of the extracranial internal carotid artery, were selected from our series of PTA if follow-up was > 12 months. All of them were followed with extracranial continuous-wave Doppler. RESULTS: Restenosis of any degree was found in 17 cases (21.79%) and always asymptomatic. A restenosis > or = 70% was found in 5 cases (6.4%). Restenosis was mainly found in cases without residual stenosis nor dissection after PTA (p = 0.002). Restenosis was found in 16 cases (94.11%) in the first 6-months, with no progression thereafter. Remodeling of residual stenosis was frequent (17 cases; 53.11%) and found mainly during the first month after PTA. Its incidence was highest in patients with dissection treated with heparin. In cases with restenosis, remodeling was infrequent, incomplete and occurred after 18-24 months. CONCLUSIONS: 1. Significant restenosis after PTA due to myointimal proliferation, was infrequent. All cases were asymptomatic, under antiplatelet treatment. A new interventional procedure might not be necessary. 2. Complete remodeling was frequently found after 1-month control, mainly in arteries with some residual stenosis and dissection after PTA.     

Management of intracoronary thrombosis complicating percutaneous transluminal coronary angioplasty

With technological advances in equipment and increased experience of operators, the success rates of percutaneous transluminal coronary angioplasty (PTCA) now exceed 90%. However, acute periprocural occlusion continues to complicate approximately 6% of all procedures, and many of these occlusions are due to intracoronary (IC) thrombus. Patients at highest risk for this complication include those with acute ischemic syndromes or with angiographically apparent thrombus. These individuals may be candidates for the use of prolonged heparin infusions prior to dilatation, intracoronary thrombolytic therapy, or monoclonal antibody directed against the platelet glycoprotein IIb/IIIa receptor. All patients undergoing PTCA should receive adequate antiplatelet therapy, including aspirin, and heparin with dosing monitored by activated clotting times (ACT). In addition, some recommend the use of ionic contrast material. When IC thrombus accumulates following intervention, initial therapy should include IC nitroglycerin followed by a combination of redilatation and IC urokinase infusion. Prolonged balloon inflations may be useful, particularly with the use of autoperfusion catheters. Platelet glycoprotein IIb/IIIa receptor antagonists may prove to be beneficial in this situation as well. If the patient's clinical status deteriorates in spite of these measures, emergency coronary artery bypass graft surgery may be required.     

Coronary artery fistula as a complication of percutaneous transluminal coronary angioplasty

The aim of this study was to assess the quality of storage of tetanus vaccine in accident and emergency (A&E) departments and also of the awareness of Department of Health guidelines. A postal questionnaire was sent to 50 randomly selected major A&E departments in the British Isles, enquiring about awareness of Department of Health guidelines (Department of Health, 1990). Forty (80%) A&E departments responded. Only 14 were aware of the Department of Health guidelines and in only 18 was there a member of staff taking responsibility for vaccine storage. The study found that safe storage of vaccine, and therefore guarantee of efficacy, is not occurring in the majority of A&E departments. Unnoticed failure of refrigerators could be exposing patients to the risk of tetanus infection.     

Outcome of percutaneous transluminal coronary angioplasty in patients with subclinical hypothyroidism

Recent advances in bone research have employed novel cell and molecular biology techniques to determine some of the fundamental mechanisms regulating bone function. Endocrine control of bone cell development and matrix turnover have been defined at a molecular level by studying the interaction of steroid/thyroid hormones with gene promoters. New steroid/thyroid hormone receptors have been cloned, suggesting that our current view of hormonal regulation of bone metabolism is far from complete. The function of one particular steroid hormone receptor, the vitamin D receptor, has come under close scrutiny following the observation that polymorphic variations in this receptor are linked to differences in bone mineral density. Detailed studies of bone cell differentiation have shown that cytokines may be particularly important targets for hormonal control in bone. The role of cell adhesion molecules in regulating bone resorption has also been explored; modulation of their activity may be of benefit in the treatment of diseases such as osteoporosis. Pharmacological intervention via the newly cloned calcium-sensing receptor offers another site for regulation of bone turnover.     

Perioperative cardiovascular morbidity in patients with coronary artery disease undergoing vascular surgery after percutaneous transluminal coronary angioplasty

PURPOSE: To develop a method for receiver operating characteristics (ROC) studies in mammography. MATERIAL AND METHODS: We developed a phantom based on excised breast tissue and overlay tiles that could be arranged in an arbitrary pattern across the surface of the breast tissue. Some of the tiles contained structures simulating calcifications or masses that produced image contrast near the experimentally determined detection threshold. Based on this phantom, a methodology for performing ROC studies in mammography was developed. The ROC curves were constructed from reporting schemes filled in by radiologists at five different laboratories. The curves were determined by a novel method: a non-linear least-squares fit of a mathematical model to the data. RESULTS: There were large differences among the areas under the ROC curves obtained from the five laboratories.     

The effect of pravastatin on prevention of restenosis after successful percutaneous transluminal coronary angioplasty

Numerous attempts have been made to prevent late restenosis after successful percutaneous transluminal coronary angioplasty (PTCA), but there is still no effective treatment. This report describes the effect of an oral lipid-lowering agent, pravastatin, on restenosis after successful PTCA. Sixty-six patients who underwent successful elective PTCA were assigned to a pravastatin-treated group (Group 1, n = 29) or an untreated group (Group 2, n = 37) in a prospective and randomized fashion. Pravastatin (5 mg or 10 mg twice a day) was given to Group 1 patients from day 3 after the procedure. Selective coronary angiography was repeated 3 to 5 months later, or sooner if the patient developed angina pectoris. The serum cholesterol level was decreased significantly in Group 1 (from 215.7 +/- 44.3 mg/dl to 181.2 +/- 30.3 mg/dl, p < 0.001), but not in Group 2 (from 191.9 +/- 30.8 mg/dl to 191.8 +/- 33.3 mg/dl, p = ns), at the time of repeat coronary angiography. However, there were no differences between the groups with regard to the recurrence of angina, the need for repeat PTCA, or restenosis, as assessed by quantitative analysis of coronary cineangiograms. These results suggest that oral pravastatin therapy does not effectively prevent late restenosis after successful PTCA by this mode of administration.     

Usefulness of percutaneous transluminal coronary angioplasty in silent myocardial ischemia

The usefulness of percutaneous transluminal coronary angioplasty (PTCA) was assessed in patients with exercise-induced asymptomatic myocardial ischemia (silent ischemia) and compared with exercise-induced symptomatic myocardial ischemia (symptomatic ischemia). Patients with single vessel coronary artery disease (51 with angina pectoris, 40 with old myocardial infarction) and evidence of stress-induced ischemia on thallium-201 single photon emission computed tomography (SPECT) underwent successful PTCA. Thirty-seven percent of angina patients and 60% of infarction patients showed asymptomatic exercise-induced ischemia. There was no significant difference in population characteristics between silent and symptomatic patients. Patients with silent angina had significantly higher percentage thallium uptake and washout rate than symptomatic patients. After PTCA, both percentage diameter stenosis and percentage thallium uptake were improved in all patients with angina irrespective of the presence or absence of symptoms. There were no significant differences in percentage thallium uptake and washout rate between patients with silent and symptomatic infarction. After PTCA, percentage diameter stenosis, percentage thallium uptake, and washout rate improved in all infarction patients irrespective of the symptoms. Zero percent of silent angina patients, 12% of symptomatic angina patients, 12% of silent infarction patients, 19% of symptomatic infarction patients had cardiac events during about 4.5 years after PTCA. The incidence of cardiac events did not significantly differ in any patient group. PTCA improved myocardial perfusion in all patients, and the incidence of cardiac events did not differ between the silent and symptomatic groups. Revascularization with PTCA is suitable for patients with silent as well as symptomatic ischemia.     

Secondary prevention in patients before and after percutaneous transluminal coronary angioplasty: 5-year follow-up

Several studies have demonstrated substantial risk reduction by risk factor modification in patients with established coronary artery disease. The number of studies investigating the implementation of risk factor intervention in clinical practice, however, is limited. We have, therefore, recorded drug use and cardiovascular risk factors in all 148 patients who had undergone percutaneous coronary angioplasty (PTCA) in 1989 at the University Hospital, Zurich, on hospital admission, after 6 months and 5 years later. Most patients had antithrombotic treatment with little change over time (78%, 87% and 83% on admission, after 6 months and after 5 years respectively, p = 0.27). The use of beta-blockers decreased moderately after 5 years (73%, 81% and 61% respectively, p < 0.01). Calcium channel blockers were used frequently without significant change in the follow-up period (56%, 50% and 46%, p = 0.25). Five years after PTCA, 91% of patients with a history of hypertension were on antihypertensive drugs. The use of lipid-lowering drugs increased markedly (5%, 16% and 33% respectively, p < 0.01). However, only a small proportion of patients qualifying for lipid-lowering drugs according to Swiss guidelines were treated. The proportion of current smokers decreased from 26% on hospital admission in 1989 to 12% in 1994. We conclude that in our study population secondary prevention was generally satisfactorily implemented. However, better monitoring and treatment of increased lipid levels is mandatory.     

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.