Percutaneous transluminal coronary angioplasty (PTCA) was first introduced by Andreas Gruentzig in 1977 as an alternative to coronary bypass surgery. The concept of percutaneous dilatation of the atherosclerotic peripheral vessels was initially demonstrated by Charles Dotter in 1964 in peripheral vessels where rigid catheters of graduated diameter were used to progressively enlarge the vessel lumen. The development of a small inelastic balloon catheter by Gruentzig allowed expansion of the technique into smaller peripheral and coronary vessels. Initial coronary experience was limited to the small percentage of patients who had single-vessel coronary disease and discrete proximal lesions due to the technical limitations of the equipment. Advances in technology and greater operator experience allowed the procedure to grow rapidly with expanded use in patients with more complex lesions and multivessel disease; by 1990 it was being performed in more than 300,000 patients annually. The addition of atherectomy devices that removed plaques aided in the growth of the procedure, but the introduction of coronary stents in 1994 was one of the major advances in the field. These devices reduced acute complications and reduced by half the significant problem of restenosis (or recurrence of the stenosis). Further reductions in restenosis were achieved by the introduction of drug-eluting stents in 2003. These stents have a polymer coating over the metal stent that is impregnated with antiproliferative agents that slowly release drugs directly into the plaque over a few months. Today, more than 1 million stents are placed in the United States per year and more than 4 million worldwide. Percutaneous coronary intervention (PCI) is the most common revascularization procedure in the United States and is performed nearly twice as often as coronary artery bypass surgery.
The field of interventional cardiology has matured to be recognized as a separate discipline in cardiology that requires specialized training. A dedicated 1-year interventional cardiology fellowship following a 3-year general cardiology fellowship and a separate board certification examination are now required to be certified in interventional cardiology. The discipline has also expanded to include interventions for structural heart disease including treatment of congenital heart disease, and valvular heart disease; it also includes interventions to treat peripheral vascular disease, including atherosclerotic and nonatherosclerotic lesions in the carotid, renal, aortic, and peripheral circulations.
The initial procedure is performed in a similar manner as a diagnostic cardiac catheterization (Chap. 230). As is done with diagnostic catheterization, arterial access is obtained by percutaneous needle puncture into a peripheral artery. Most commonly, the arterial access site is the femoral artery, but radial artery access is gaining favor. To prevent thrombotic complications during the procedure, patients who are anticipated to need an angioplasty are given aspirin (325 mg) and clopidogrel (loading dose of 300–600 mg) before the procedure. During the procedure, anticoagulation is achieved by administration of unfractionated heparin, enoxaparin (a low-molecular-weight heparin), or bivalirudin (a direct thrombin inhibitor). In patients with ST-elevation myocardial infarction, high-risk acute coronary syndrome, or those with a large thrombus in the coronary artery, a glycoprotein IIb/IIIa inhibitor (abciximab, tirofiban, or eptifibatide) may also be given.
Following placement of an introducing sheath, preformed guiding catheters are used to cannulate selectively the origins of the coronary arteries. These catheters have larger internal diameters than diagnostic catheters in order to allow passage of the balloon catheter and wires. Through the guiding catheter, a flexible, steerable guidewire (diameter 0.4 mm) is negotiated down the coronary artery lumen using fluoroscopic guidance; it is then advanced through the stenosis and into the vessel beyond. This guidewire then serves as a "rail" over which angioplasty balloons, stents, or other therapeutic devices can be advanced to enlarge the narrowed segment of coronary artery. The artery is usually dilated with a balloon catheter and most often a stent is then placed with assessment of the final result by repeat angiography through the guiding catheter. The catheters and introducing sheath are removed and the artery manually held or closed using one of several arterial closure devices to achieve hemostasis. Because PCI is performed under local anesthesia and mild sedation, it requires only a short (1-day) hospitalization that decreases recovery time and hospital expense, as compared to coronary bypass surgery.
The inflated diameter of the angioplasty balloons range in size from 1.5 mm to 4.0 mm, and balloons are chosen to approximate the "normal" less diseased proximal or distal vessel without stenosis. The major advance introduced by Dr. Gruentzig was the use of inelastic balloons that do not overexpand the vessel beyond their predetermined size despite high pressures up to 10–20 atmospheres.
Angioplasty works by stretching the artery and compressing the plaque into the vessel wall, away from the lumen, enlarging the entire vessel (Figs. 246-1 and 246-2). The procedure rarely results in embolization of atherosclerotic material. Owing to inelastic elements in the plaque, the stretching of the vessel by the balloon results in small localized dissections that can protrude into the lumen and be a nidus for acute thrombus formation. If the dissections are severe, then they can obstruct the lumen or induce a thrombotic occlusion of the artery (acute closure). Stents have largely prevented this complication by holding the dissection flaps up against the vessel wall (Fig. 246-1).
Schematic diagram of the primary mechanisms of balloon angioplasty and stenting. A. A balloon angioplasty catheter is positioned into the stenosis over a guidewire under fluoroscopic guidance. B. The balloon is inflated temporarily occluding the vessel. C. The lumen is enlarged primarily by stretching the vessel often resulting in small dissections in the ...
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