Field Of Interventional Cardiology Research Articles

Recent advances in interventional pediatric cardiovascular disease.

Transcatheter therapy in children with congenital or acquired heart disease is a challenging, innovative, and constantly evolving field. In this article we review the various "nonsurgical" techniques that are currently available, with a discussion of their applications and an update on the recent advances in the field of interventional cardiology.

Treatment Strategies for Bifurcation Lesions

Percutaneous transluminal angioplasty of coronary artery bifurcations represents a still evolving field of interventional cardiology. The dilatation of stenoses located at the site of coronary bifurcations has been limited by the risk of side branch occlusion with subsequent myocardial infarction and high rates of late restenosis. The initial success rates of conventional balloon dilatation were improved by the introduction of side branch protection using two guidewires as well as the “kissing balloon” technique. The potential advantage of atherectomy techniques, however, was associated with a high incidence of acute complications. While bifurcation stenting promises to allow optimal geometric reconstruction of bifurcation lesions using multiple or single component bifurcation stents, late intimal hyperplasia remains a potential limitation of this interventional approach.

Recent advances in interventional pediatric cardiovascular disease.

Transcatheter therapy in children with congenital or acquired heart disease is a challenging, innovative, and constantly evolving field. In this article we review the various "nonsurgical" techniques that are currently available, with a discussion of their applications and an update on the recent advances in the field of interventional cardiology.

A call for provisional stenting: the balloon is back!

During the past 20 years, the equipment used to perform percutaneous coronary revascularization has undergone a dramatic transformation from simple balloon dilatation catheters to sophisticated mechanical devices and endoprostheses. The impetus for this evolution in technology was initially a byproduct of suboptimal immediate and long-term results obtained with standard balloon angioplasty. New techniques, including directional and rotational atherectomy, have resulted in improved procedural success rates, especially for more complex lesion subtypes, although their ability to curtail restenosis remains controversial.1 2 Intracoronary stents have had a dramatic impact on reduction of the incidence of acute complications after failed balloon angioplasty and represent the only currently available strategy shown to limit both clinical and angiographic restenosis.3 4 5 6 7 8 9 10 11 12 Based on these advantages, stent implantation is used in approximately half of all percutaneous interventions in the United States. However, despite their proven benefits, coronary stents continue to be accompanied by several theoretical and practical limitations: they are costly, typically associated with a more marked degree of neointimal formation than balloon angioplasty, and difficult to use with some lesion subsets such as bifurcation stenoses, and they have engendered the new and difficult-to-treat entity of in-stent restenosis. Although the major focus in the field of interventional cardiology over the past decade has been on the development of new devices and adjunctive pharmacological therapies, the short- and long-term success rates after standard balloon angioplasty have improved significantly. Part of the improvement is likely a manifestation of enhanced operator experience and better equipment, but the results of balloon angioplasty have also benefited greatly from the availability of coronary stents for both “bailout” (for actual or threatened abrupt closure) or “backup” (for suboptimal balloon results) indications, potentially allowing a strategy of more aggressive balloon dilatation than could be safely …

Frontiers in interventional cardiology.

n more than 20 years since the first percutaneous coronary revascularization procedures, the field of interventional cardiology has proliferated beyond all expectations. Now more than 1 million procedures are performed worldwide each year. Stenting has revolutionized the field, which previously relied on balloon dilatation in the majority of patients. With 50% of patients now undergoing stent implantation, the groundwork is laid for further important advances. In this article, we discuss the 4 most important new advances in the field of interventional cardiology: platelet inhibition, prevention of restenosis, stent evolution, and angiogenesis.

Local Catheter-Based Intracoronary Radiation Therapy for Restenosis

Intracoronary radiation therapy was shown to be effective in limiting “restenosis-like” phenomena by inhibiting neointima formation after balloon angioplasty in porcine coronary arteries. Using the same treatment doses, both gamma and beta emitters demonstrated similar results, despite differences in isotope characteristics (e.g., penetration, activity, dose rate, and treatment time). In addition, intracoronary radiation delivered via a catheter-based system prior to coronary stenting reduced neointimal hyperplasia in the porcine model and may further reduce restenosis when coupled with stent implantation. Radioactive stents are of value, especially in large vessels, because of their low activity and proximity to the vessel wall. Adventitial labeling and immunostaining have suggested that the mechanisms by which radiation reduces restenosis are (1) inhibition of smooth muscle cell proliferation in the adventitia and (2) favorable effects on vessel remodeling. Technical radiation considerations are also discussed, including isotope selection, treatment dose, homogeneous dosimetry, treatment time, and total body dose to the patient and healthcare personnel. New catheter-based delivery systems for intracoronary use are currently being developed and are described. Preliminary clinical and angiographic studies using endovascular radiation after balloon angioplasty in both stented and nonstented peripheral and coronary arteries indicate favorable long-term results. In response to the growing enthusiasm for this approach, larger populations must be studied to determine whether this new therapy will influence the restenosis rate and clinical events after angioplasty and, in a broader sense, the field of interventional cardiology. (Am J Cardiol 1996;78(suppl 3A):23–28)

The use of activated clotting times to monitor heparin therapy during and after interventional procedures.

Use of the activated clotting time (ACT) was recommended in the mid 1970s to guide administration and reversal of heparin during cardiopulmonary bypass. As the applications of cardiopulmonary bypass spread, so too did the need for more efficient techniques to assess coagulation status. This led to the development of automated ACT measurements. Today, the importance of coagulation and anticoagulation has been further highlighted by recent advances in the field of interventional cardiology. More and more cardiologists are using in-laboratory bedside coagulation monitoring to assess heparin requirements during interventional procedures such as percutaneous transluminal coronary angioplasty (PTCA). This review focuses on the development of anticoagulation monitoring and provides historic information on the clinical use of heparin. The application of ACTs in the catheterization laboratory and in other clinical situations is discussed, along with alternative methods for bedside assessment of coagulation status. No definite guidelines have been established for ACT monitoring during invasive intravascular procedures; thus its role continues to be refined. In the meantime, the ACT appears to be an extremely useful method for monitoring heparin therapy and the adequacy of anticoagulation.

Quantitative coronary angiography (QCA) in interventional cardiology: Clinical application of QCA measurements

Q UANTITATIVE coronary angiography (QCA) has had a tremendous impact in the field of interventional cardiology. Because of its superior accuracy and objectivity, QCA has supplanted visual and hand-held caliper assessments of coronary arteriograms and has improved interobserver and intraobserver variability. 1-3 QCA is now the gold standard for the assessment of the coronary tree in the context of scientific research, 4 although it has not yet gained widespread appeal for routine clinical use. 5 Until very recently, mainly because of the expense and time-consuming aspect involved in routine clinical application of sophisticated computer-based analysis, QCA has only been available for off-line use. 6-9 In addition, the extra precautions that must be taken by the angiographer in obtaining images suitable for quantitative analysis 1~ imply that many angiograms routinely performed by busy clinicians or in acute or emergency situations may not be analyzable by an automated computer-based system. 5 However, with the progressively increasing number of clinics involved in multicenter restenosis prevention trials in which QCA plays an integral role, 1H3 perhaps these extra precautions may become routine clinical practice. QCA has been particularly useful in interventional cardiology as the only objective and reliable means of assessing the immediate and long-term effects of coronary interventions. In particular, the phenomenon of restenosis has primarily been described and researched most extensively on the basis of sequential QCA studies. At the Thoraxcenter (Rotterdam, The Netherlands), we have been advocating the importance of QCA since the first report of its use by our group in 1978 TM and, subsequently, with renewed vigour after our initial experience with QCA in the assessment of coronary interventions, as reported in 1982.15 The Cardiovascular Angiographic Analysis System (CAAS) has been extensively and rigorously validated, 16-18 and technical aspects are presented in the accompanying report. The entire angiographic database now consists of collected information from more than 5,000 patients who have undergone several different forms of nonoperative coronary revascularization. The principles of QCA, which were initially designed for diagnostic studies of coronary artery disease (CAD), have necessarily been adapted to more complex situations related to either the presence of a device or the effect of an intervention on the angiographic appearance of a damaged vessel. The introduction of several newer devices in the past 7 years, has presented a number of unique and unforeseen problems in image analysis and the subsequent interpretation of important quantitative data, as described in the accompanying report. The emergence of digital subtraction angiography has allowed on-line performance of QCA measurements in the catheterization laboratory, so that a technique previously confined to research applications has been transformed into a powerful analytic tool, directly applicable to clinical decision making. 7,19 The immediate availability of QCA measurements during interventional procedures provides a unique opportunity for more accurate selection of appropriate interventional devices (eg, balloon, stent, or atherotome dimension) and for continuous monitoring and immediate evaluation of the result obtained. During the last 5 years at the Thoraxcenter, a large clinical experience has been accumulated through the application of the Philips Digital Cardiac Imaging (DCI) Automated Coronary Analysis System. 6,9 In vivo study of stenosis phantoms placed in porcine

Advances in Interventional Cardiology

The field of interventional cardiology is growing widely. This growth is the result of improvements in existing technology, development of new technology, and expansion of criteria for the selection of patients. Percutaneous transluminal coronary angioplasty (PTCA) remains the mainstay and is used to treat an increasing number of patients with coronary artery disease that manifests as stable or unstable angina or acute myocardial infarction. Atherectomy is being used to "debulk" lesions and remove atheromatous plaque as well as to remove intimal flaps after PTCA. The insertion of an intracoronary stent is a strategy designed to treat intimal dissections and acute closure as well as to attempt to decrease the incidence of restenosis. Finally, intracoronary laser therapy--independently or in combination with PTCA--is being evaluated as a treatment approach for more diffuse disease, acute occlusion, and prevention of restenosis.