Status of percutaneous transluminal coronary angioplasty.
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Angioplasty, Balloon, Coronary↗
Biomedical subjects
G S Roubin
Publications and source records attributed to G S Roubin.
Hemodynamic and metabolic basis of impaired exercise tolerance in patients with severe left ventricular dysfunction.
Hemodynamic and metabolic changes were measured at rest and during exercise in 23 patients with chronic heart failure and in 6 control subjects. Exercise was limited by leg fatigue in both groups and capacity was 40% lower in the patients with failure. At rest, comparing patients with control subjects, heart rate and right atrial and pulmonary wedge pressure were higher; cardiac output, stroke volume and work indexes and ejection fraction were lower; mean arterial and right atrial pressure and systemic resistance were similar. During all phases of exercise in patients with heart failure, pulmonary wedge pressure and systemic vascular resistance were higher and pulmonary vascular resistance remained markedly elevated compared with values in control subjects. Cardiac output was lower in the patients with failure, but appeared to have the same physiologic distribution in both groups during exercise. Although arterial-femoral venous oxygen content difference was higher in patients with heart failure, this increase did not compensate for the reduced blood flow. Even though the maximal oxygen consumption was significantly reduced, femoral venous lactate and pH values were higher than values in control subjects, but femoral venous pH was similar in both groups at their respective levels of maximal exercise. Ejection fraction was lower in those with heart failure at rest and did not increase with exercise. Ventilation in relation to oxygen consumption was higher in patients with failure than in control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Trapidil in preventing restenosis after balloon angioplasty in the atherosclerotic rabbit.
Trapidil (triazolopyrimidine) possesses activity against platelet-derived growth factor-induced cellular proliferation in vitro and intimal proliferation in vivo. The objective of this study was to determine if trapidil could prevent restenosis in experimentally induced atherosclerotic rabbits. New Zealand White rabbits with preexisting iliac arterial lesions induced by balloon deendothelialization underwent balloon angioplasty. Arteriography was performed before, immediately after, and 4 weeks after the balloon dilatation. Tissue sections of the dilated arterial segment were also analyzed morphometrically. Seventeen rabbits were randomized to two groups: a control group (n = 8) and a trapidil-treated group (n = 9). The treatment group received 30 mg/kg s.c. trapidil twice daily. The angiographic luminal diameters before and after dilatation were similar. At the 4-week restudy, there was a significant preservation of luminal diameter in the trapidil group compared with the control group (1.27 +/- 0.20 vs. 0.94 +/- 0.48 mm, respectively; p less than 0.005). When luminal diameters immediately after dilatation were compared with diameters at the 4-week restudy (i.e., when the degree of restenosis was assessed), there was a greater luminal diameter reduction in the control group than in the trapidil group (0.70 +/- 0.44 vs. 0.30 +/- 0.25 mm, respectively; p = 0.005). By morphometric analyses, the luminal areas were also greater in the trapidil group than the control group (0.80 +/- 0.25 vs. 0.57 +/- 0.33 mm2, respectively; p = 0.03). Intimal thickness was significantly less for the trapidil group than for the control group (0.33 +/- 0.15 vs. 0.44 +/- 0.15 mm, respectively; p = 0.01), as well as medial thickness (0.09 +/- 0.03 vs. 0.11 +/- 0.03 mm, respectively; p = 0.01). In this study, trapidil significantly increased the luminal area and reduced the intimal thickness in the atherosclerotic rabbit iliac artery after balloon angioplasty.
Angioplasty, Balloon↗
Adjuvant therapy for intracoronary stents. Investigations in atherosclerotic swine.
Early thrombosis has complicated human stent implantation in several trials. To determine the best anticoagulation/antiplatelet therapy to maintain stent patency after percutaneous transluminal coronary angioplasty, we implanted the flexible balloon-expandable coil stent into the left anterior descending coronary artery of 28 atherosclerotic 8-month-old Hanford miniature swine. Animals were randomly assigned to one of three treatment groups: group A, aspirin (1 mg/kg/day) and dipyridamole (1 mg/kg three times a day); group B, aspirin and dipyridamole (same doses) plus Coumadin (dose required to prolong prothrombin time 1.3-1.5-fold that of normal); and group C, control. Adjuvant therapy was begun 3 days before stenting. Two pigs (one from group A and one from group B) died during implantation, both without thrombosis. Twenty-six animals survived until follow-up angiography and sacrifice at 1 month. No occlusive thrombosis of the stent occurred in survivors. Reduction of the stent lumen diameter was observed in every case at follow-up. Percent lumen reduction was 19% in group A, 26% in group B, and 24% in group C. Marked smooth muscle cell hyperplasia was seen by light and transmission electron microscopy at stent struts. Scanning electron microscopy of the luminal surface showed a variable morphology consisting of normal endothelium, adherent leukocytes, stellate periluminal cells, and occasional fibrin strands and red blood cells. Luminal narrowing was not affected by anticoagulation therapy, antiplatelet drugs, cholesterol level, or stent sizing. We conclude that occlusive thrombosis does not complicate stent implantation in this model but that substantial luminal narrowing due in part to smooth muscle hyperplasia does occur. The significance of luminal narrowing at the stent site requires further study.
Angiography↗
Failed elective percutaneous transluminal coronary angioplasty requiring coronary artery bypass surgery. In-hospital and late clinical outcome at 5 years.
This study was performed to define the in-hospital and late clinical outcome at 5 years in 430 patients who had a failed elective percutaneous transluminal coronary angioplasty (PTCA) and underwent coronary artery bypass graft (CABG) surgery during their hospitalization. This group comprised 5.9% of 7,246 patients undergoing elective PTCA. CABG surgery was performed in 346 patients with ongoing myocardial ischemia (80.5%) and in 84 patients without ischemia (19.5%). Their mean age was 56 +/- 9 years, and 76.3% were male. One-vessel disease was present in 72.3%, and the mean left ventricular ejection fraction was 59 +/- 11%. Overall, 1.9 +/- 0.9 bypass grafts were placed. There was increased use of the internal thoracic artery in the nonischemic group. A new nonfatal postprocedural Q wave myocardial infarction occurred in 21.2% and occurred more frequently in the ischemic (25.4%) than in the nonischemic (3.6%) group (p less than 0.0001). There were six in-hospital deaths (1.4%), an incidence that did not differ between the two groups. Follow-up was 99.8% complete. There were 25 deaths (93.2 +/- 1.5%, 5-year survival), including 16 of cardiac cause (95.3 +/- 1.3%, 5-year cardiac survival). Q wave myocardial infarction occurred in 111 patients (91 in-hospital), and freedom from cardiac death or nonfatal myocardial infarction at 5 years was 71 +/- 3%. In the group going to CABG surgery with ongoing ischemia, the 5-year cardiac survival was 94.9 +/- 1.6%, and in the group without ischemia, the corresponding survival was 96.2 +/- 2.2%. By multivariate analysis, the presence of preoperative myocardial ischemia, pre-PTCA diameter stenosis less than 90%, and the presence of multiple-vessel disease correlated with the occurrence of cardiac death or nonfatal myocardial infarction at 5 years. At this large-volume center with extensive PTCA operator and surgical experience, the excellent survival and low event rates over 5 years support the concept that despite the failed elective PTCA procedure, there was little effect on long-term survival provided the patient underwent prompt successful surgical revascularization.
Aged↗
Intracoronary stenting during percutaneous transluminal coronary angioplasty.
A flexible, balloon-mounted, coil stent was developed to address the problems of acute closure and long-term restenosis, which currently limit the safety and efficacy of percutaneous transluminal coronary angioplasty. The device is made of 0.006-in. stainless steel suture material and is mounted on balloons, 2.5-4.5 mm in diameter, for use in the coronary circulation. Results of studies in canine coronary arteries have demonstrated long-term patency and stability, and studies in the atherosclerotic arteries of rabbits have suggested late results with stenting that might be superior to those obtained with balloon angioplasty alone. Initial clinical studies have focused on the use of the device as a "bridge" to surgery if closure occurs. The stent appears to have been successful in this application. A phase 2 study is now examining the stent as definitive therapy for acute closure in certain anatomic subsets of patients. Information on long-term patency is pending. If this is favorable, the device will be studied to see if it reduces the incidence of restenosis in the subset of patients in whom balloon dilatation alone fails to produce an optimal hemodynamic result.
Angioplasty, Balloon, Coronary↗
Postcatheterization vascular complications associated with percutaneous transluminal coronary angioplasty.
The threat of a vascular complication exists in association with any percutaneous arterial catheterization, but is greater in the more complex interventional techniques. During a 3 1/2-year period from January 1985 through June 1988, 4988 percutaneous transluminal coronary angioplasty procedures were performed at Emory University Hospital. All patients were given heparin during the cardiac intervention, and all had a catheter introducer left in place for several hours after completion of the procedure. Fifty-five iatrogenic vascular complications developed in 52 patients (1%), resulting in 54 corrective operations. Pseudoaneurysm, the most frequent complication, was seen in 35 patients (64%). This was followed by arteriovenous fistula in eight (15%), uncontrolled hemorrhage in six (11%), arterial thrombosis in three (6%), peripheral embolization in two (4%), and bowel ischemia in one patient. The outcome of surgical therapy in the entire group was quite acceptable with no operative mortality, no extremity amputation, and a 7.4% complication rate. Variables that correlated with an increased risk of peripheral vascular problems after percutaneous transluminal coronary angioplasty included advanced age, female gender, thrombolytic therapy, and postprocedural anticoagulation. Variables that did not appear to correlate were hypertension, diabetes, prior percutaneous transluminal coronary angioplasty, antiplatelet therapy, or the size of the guiding catheter used.
Aged↗
Risk factors, time course and treatment effect for restenosis after successful percutaneous transluminal coronary angioplasty of chronic total occlusion.
Advances in technology and operator experience, and increased use of angiography early after myocardial infarction have led to greater use of percutaneous transluminal coronary angioplasty (PTCA) for chronic, total coronary artery occlusions. To better assess long-term outcome, 257 consecutive patients with successful PTCA of a total occlusion with late angiographic follow-up from 484 patients (53%) with PTCA success were reviewed. The mean +/- standard deviation patient age was 54 +/- 10 years, 79% were men, the duration of total occlusion was 11 +/- 15 weeks and the post-PTCA diameter stenosis was 24 +/- 12%. Eighty-two, 27 and 63% of patients received long-term aspirin, dipyridamole and warfarin therapy, respectively. Angiography at 8 +/- 8 months demonstrated restenosis (greater than or equal to 50% diameter stenosis) in 41% of patients restudied within 6 months and in 66% of patients restudied within 12 months by life table analysis. In multivariate regression analysis of 19 variables, 2 were independently correlated with the occurrence of restenosis: post-PTCA diameter stenosis greater than 30% (p = 0.02) and coronary artery dilated (left anterior descending and right coronary arteries greater than the left circumflex coronary artery) (p = 0.05). In log rank analysis that also considered the timing of angiographic detection of restenosis, dilatation of a proximal left anterior descending stenosis was also a significant predictor of restenosis (p = 0.01), and dilatation within 4 weeks of the presumed time of occlusion was only weakly predictive (p = 0.11).(ABSTRACT TRUNCATED AT 250 WORDS)
Angioplasty, Balloon↗
Importance of stenosis morphology in the estimation of restenosis risk after elective percutaneous transluminal coronary angioplasty.
To determine the importance of predilatation stenosis morphology on the risk of restenosis after percutaneous transluminal coronary angioplasty (PTCA), 500 procedures were randomly chosen for analysis from 3,839 consecutive successful PTCA procedures. Angiographic follow-up was available for 308 patients (62%) at a mean of 7.3 +/- 3.4 months after PTCA. One dilated site was randomly chosen per procedure. One hundred and one sites had documented restenosis (greater than or equal to 50% mean diameter stenosis from multiple projections) by quantitative angiography (33% of all sites restudied and 20% of all sites dilated). Twenty-eight morphologic variables and 20 other angiographic, clinical and procedural variables were analyzed by an observer blinded to clinical outcome. Univariate analysis found post-PTCA percent stenosis greater than 30% (p = 0.005), bend point location (p = 0.01), post-PTCA gradient greater than 15 mm Hg (p = 0.02), angina class III to IV (p = 0.03), age (p = 0.04) and the absence of dissection (p = 0.04) to predict restenosis. Multivariate analysis found only 2 significant (p less than 0.05) independent predictors of restenosis: post-PTCA percent stenosis greater than 30% and bend point location. Restenosis occurred in 41% of lesions located at an end-diastolic vessel angle greater than or equal to 45 degrees compared with 28% in lesions on lesser bends. Thus, only 1 predilatation morphologic characteristic, stenosis location at a bend point, was an important independent predictor of restenosis, and should be considered when assessing patients for PTCA.
Angioplasty, Balloon↗
Sequential multivessel coronary angioplasty assessed by thallium-201 tomography.
In 11 patients with multivessel coronary artery disease, SPECT thallium-201 imaging was performed prior to and within 3 days after each of two sequential percutaneous transluminal coronary angioplasties on separate days designed to achieve total revascularization. Thallium-201 SPECT was analyzed quantitatively, and an ischemic score for the vascular bed(s) supplied by the dilated vessel(s) was derived. For the vessels dilated during the first procedure the mean diameter stenosis was 80 +/- 8%, reduced to 27 +/- 9%. For the second procedure mean stenosis was reduced from 67 +/- 10% to 26 +/- 6%. For the two procedures, the mean thallium scores decreased from 298 +/- 225 to 115 +/- 130 (P less than .001) and from 135 +/- 129 to 46 +/- 60 (P less than .001), respectively. Of 10 patients with abnormal thallium-201 SPECT prior to angioplasty, nine improved after the first procedure, and seven improved further following the second procedure. Thus, utilizing staged angioplasty with a strategy of dilating the most severe lesion first, thallium-201 SPECT documented progressive improvement in myocardial perfusion.
Angioplasty, Balloon, Coronary↗
Comparison of coronary angioplasty with medical treatment for single- and double-vessel coronary disease with left anterior descending coronary involvement: long-term outcome based on an Emory-CASS registry study.
The 3 to 5-year clinical outcomes of 627 consecutive patients selected for treatment with percutaneous transluminal coronary angioplasty (PTCA) at Emory University Hospital for one- or two-vessel coronary artery disease with involvement of the left anterior descending coronary artery, between July 1981 and June 1983, and 865 patients in the Coronary Artery Surgery Study with similar coronary artery disease involvement selected for medical therapy between 1975 and 1979 were compared. Cox analyses and stratified life table analyses were used to adjust for differences in 13 variables including concurrent medical therapy. Complete follow-up was obtained in 97% of PTCA patients and 99% of medically treated patients. After correction for baseline differences in significantly predictive variables, there was no difference between the relative risk of death after PTCA vs medical therapy (RR = 0.7; p = 0.36). However, results of analysis of prospectively defined subsets showed a potential survival benefit after PTCA for patients with an ejection fraction less than 50% (RR = 0.2; p = 0.02) and also for patients with two-vessel disease (RR = 0.2; p = 0.04). For the groups as a whole there was no difference in risk of infarction after PTCA and medical therapy (RR = 0.8; p = 0.58). However, for patients with 90% to 99% LAD stenosis there was a trend toward lessened risk of infarction after PTCA (RR = 0.6; p = 0.15). No patient subset had a higher risk of death or infarction with PTCA (p less than or equal to 0.15). The likelihood of later surgery was increased after PTCA (RR = 1.5; p = 0.002). Angina, employment, and activity levels were improved after PTCA. Thus PTCA compared to medical therapy was associated with improved functional status and may decrease the risk of death and infarction in certain patient subsets. However, bypass surgery was more often performed in patients initially treated with PTCA. These data should be interpreted in light of their nonrandomized study origin and generation from different clinical sites.
Activities of Daily Living↗
Effect of 18- to 24-hour heparin administration for prevention of restenosis after uncomplicated coronary angioplasty.
Smooth muscle cell proliferation induced by intimal denudation similar to that produced by coronary angioplasty has been decreased by early and brief heparin administration in animal models. Heparin might also decrease the incidence of thrombus-induced postdenudation arterial obstruction, albiet at risk of bleeding. To evaluate the risks and benefits of heparin after coronary angioplasty, 416 patients (469 vessel sites) with successful coronary angioplasty without large dissection were randomized to heparin (titrated to partial thromboplastin time 1.5 to 2.5 times normal) or dextrose administered for 18 to 24 hours. Patients also had received heparin during angioplasty (usually 10,000 to 15,000 units), and they received aspirin for a period of 6 months. Heparin and dextrose groups were not different in the percentage of patients with male sex (74% in the heparin group and 75% in the dextrose group, p = NS), postangioplasty tear or dissection (30% in the heparin group and 30% in the dextrose group, p = NS), or postangioplasty percent stenosis greater than 35% (31% in the heparin group and 30% in the dextrose group, p = NS). Partial thromboplastin time during treatment in the heparin group was 56 +/- 22 seconds and in the dextrose group 27 +/- 9 seconds (p less than 0.001). Late angiographic follow-up (180 +/- 81 days) was achieved in 58.4% in the heparin group and 64.5% in the control group. Of patients with late angiographic follow-up, 41.2% and 36.7% randomized to heparin and dextrose, respectively, had documented restenosis (greater than or equal to 50% diameter stenosis at one or more the sites dilated) (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Marine lipid concentrate and atherosclerosis in the rabbit model.
Twenty-seven New Zealand white rabbits underwent balloon de-endothelialization of the aorta and iliac arteries while consuming a 2% cholesterol, 10% peanut oil rabbit chow. Ten of these rabbits were fed 1 ml of concentrated marine fish lipid (MaxEpaTm) daily. Six weeks after de-endothelialization, angiography of the treated arteries was performed and histologic cross-sections of the terminal aorta were measured with a planimeter. Iliac artery luminal diameters were also measured at consecutive 3-mm divisions from the aortic bifurcation and found to have a mean lumen diameter of 1.60 +/- 0.08 mm in the marine lipid-supplemented group (M) and 1.38 +/- 0.12 mm in the control group (C) (P less than 0.001). Analysis of variance on individual segmental diameters confirmed this difference. However, neither the angiographic diameters nor histologic, cross-sectional, luminal areas of the terminal aorta were different between groups. Instead, the mean cross-sectional area of the terminal aortic wall was significantly greater in the marine lipid-fed group (4.4 +/- 1.2 mm2 in M and 3.1 +/- 0.6 mm2 in C, P less than 0.01). In addition, the vessel wall area showed a positive correlation with red blood cell (RBC) incorporation of docosahexaenoic acid (r = 0.82, P less than 0.005) in both groups. In the M group, RBC eicosapentaenoic acid and docosahexaenoic acids increased 100% and 650%, respectively, over baseline.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Histopathologic phenomena at the site of percutaneous transluminal coronary angioplasty: the problem of restenosis.
Seventeen postangioplasty cases were morphologically studied at postmortem. Four of the eleven, early and intermediate cases (few hours to 1 month from angioplasty to death), revealed intraluminal thrombi, although in only two cases were those thrombi occlusive. Almost all of the nine early cases (eight of nine) exhibited intimal disruptions. Except for two of these cases in which circumferential and/or longitudinal dissections were present, the remainder of the intimal cracks were superficial and of limited extent. Limited dissection between intima and media is not considered a serious or detrimental local event. The early cases showed an aneurysmal dilatation of the plaque-free segment of the arterial wall in eccentric plaques. This finding was interpreted as the result of uneven distribution of the dilating force (circumferential stress) on the aterial wall. Late cases (survival over 1 month) revealed characteristic medial and intimal lesions indicative of the initial dilatation injury. It is hypothesized that intrinsic arterial wall changes (medial disruption) at the plaque-free segment and the resulting altered arterial geometry at the site of dilatation have a significant hemodynamic effect on the vascular conduit and may enhance and sustain the myoproliferative intimal response.
Adult↗
Comparison of the effects of nifedipine and nitroglycerin on hemodynamic determinants of myocardial oxygen consumption and supply during exertional angina.
To investigate the antianginal action of nitroglycerin and nifedipine, systemic and right heart pressures, cardiac output, oxygen consumption, and radionuclide left ventricular ejection fraction and volume were measured in 14 men with stable effort angina and a positive exercise electrocardiogram. Exercise tests were performed on a semiupright bicycle ergometer on no therapy and after intravenous nitroglycerin and sublingual nifedipine, which lowered mean arterial pressure by 20 mm Hg. Exercise tolerance improved from 50 +/- 4 to 61 +/- 5 W on nifedipine and to 79 +/- 4 W on nitroglycerin (p less than 0.01, nitroglycerin vs. nifedipine). At submaximal workloads, both drugs decreased arterial pressure and ventricular volumes, but heart rate was higher on nifedipine. At peak exercise on nitroglycerin (79 W), oxygen consumption, cardiac index, heart rate, and rate-pressure product were significantly increased over peak control and nifedipine values, while systolic pressure and end-diastolic volume were unchanged. Nitroglycerin reduced pulmonary wedge pressure more and systemic diastolic pressure less than nifedipine, so the coronary perfusion gradient was reduced by nifedipine and maintained by nitroglycerin. Also, there was less angina and ST-segment depression after nitroglycerin compared to control or nifedipine, and the left ventricular diastolic pressure-volume relationship was improved only by nitroglycerin. This suggests that the action of nitroglycerin in reducing ischemia is not only due to reduced myocardial oxygen demand, but that myocardial oxygen delivery may also be increased.
Adult↗
Tear or dissection after coronary angioplasty. Morphologic correlates of an ischemic complication.
Intimal tear or dissection is an important descriptor of ischemic complications after coronary angioplasty, but only the minority of patients will develop an acute ischemic event. To identify additional factors that may predict the development of an ischemic event when arterial disruption occurs during otherwise uncomplicated angioplasty, the records of 1,346 patients prospectively identified as having tear or dissection without immediate vessel closure were examined. Ischemic complications, defined as ischemic chest pain, myocardial infarction, the need for coronary bypass surgery, or death, occurred in 120 patients (9%). Significant multivariate correlates of an ischemic complication were the presence of unstable angina or a totally occluded vessel before angioplasty and diameter stenosis of greater than 30% after angioplasty. Detailed geometric and videodensitometric analysis of the postdilatation angiograms of a subset of 96 consecutive patients was carried out. Ischemic complications occurred in 11 patients (11%). Multivariate analysis revealed that the independent correlates of complications, in decreasing order of importance, were the length of the tear or dissection (p = 0.001), diameter stenosis after angioplasty (p = 0.001), cross-sectional area after dilatation measured by videodensitometric methods (p = 0.013), and the presence of extraluminal contrast (p = 0.044). When tear or dissection occurs during otherwise uncomplicated coronary angioplasty, patients at risk of developing delayed ischemic complications can be identified and may benefit from measures designed to minimize this risk. By controlling for the geometric or mechanical factors that result in tear or dissection, it has been possible to identify factors not previously thought associated with ischemic complications.(ABSTRACT TRUNCATED AT 250 WORDS)
Angioplasty, Balloon↗
Restenosis after coronary angioplasty. Potential biologic determinants and role of intimal hyperplasia.
Restenosis after successful PTCA remains a major problem limiting the efficacy of the procedure. The pathophysiologic mechanism of restenosis has been enigmatic so far, but accumulated evidence strongly suggests that intimal hyperplasia is the major mechanism. Based on current understanding of the process of intimal hyperplasia, one unifying concept may be that there are at least two major local biologic determinants influencing this process, lesion characteristics and regional flow dynamics. Lesion characteristics include the plaque structure and the quantity of smooth muscle. These may provide the anatomic substrate that determines the extent of injury and the degree of smooth muscle cell proliferation. The amount of smooth muscle cells in the stenotic lesion activated by injury to undergo proliferation may determine the eventual bulk of the restenotic lesion. In addition, low wall shear stress could promote intimal hyperplasia and cause structural change of vessels to decrease the lumen, whereas high wall shear stress exerts the opposite effects. Intimal hyperplasia after balloon injury is a complex process involving platelets, growth factors, endothelial cells, smooth muscle cells, mechanical injury, wall shear stress, and probably other unknown factors. Platelets not only contribute growth factors such as PDGF but also cause organized thrombus. Different growth factors may be involved in initiating smooth muscle cell proliferation and may come from many different sources, including smooth muscle cells, endothelial cells, and macrophages. Intact confluent endothelial cells may produce heparin sulfates and inhibit intimal proliferation; however, regenerating endothelial cells may have the opposite effect. Thus, the proliferative potential of smooth muscle cells, endothelial recovery, extent of injury, wall shear stress, and other unknown factors may all influence this process. Based on these concepts concerning the biology of restenosis, some research directions concerning potential forms of therapy are proposed.
Angioplasty, Balloon↗
Intravascular stents.
Restenosis and/or acute closure continue to affect at least one third of all patients undergoing coronary angioplasty; pharmacologic and mechanical methods are therefore being developed to prevent this. The current information on intravascular stents is reviewed and the potential for this device to impact on acute closure and restenosis discussed.
Angioplasty, Balloon, Coronary↗