Procedure and Equipment

PCI is performed in cardiac catheterization laboratories with the same radiographic equipment used for diagnostic coronary arteriography. Arterial access is obtained via the femoral, radial, or brachial artery (Fig. 15-2). The femoral approach is used most frequently and is the preferred method taught at most training centers. The radial approach, which has the advantage of infrequent access site bleeding complications and reduced patient morbidity due to earlier ambulation after PCI, has gained popularity in recent years. Disadvantages of the transradial approach are the significant learning curve and the potential for radial artery occlusion. The presence of a patent ulnar artery and intact palmar arch (which can be assessed by physical examination) is a prerequisite for the use of this approach and provides assurance that should radial artery occlusion occur, it will be asymptomatic.

Figure 15-2 Percutaneous coronary intervention: vascular access.

Interventional guide catheters are slightly larger than diagnostic catheters so as to accommodate balloons, stents, and other devices. After visualization of the coronary artery and target lesion via arteriography, a coronary guide wire is advanced across the lesion and positioned in the distal vessel. A small double-lumen catheter with a distal balloon is passed over the guide wire and positioned at the lesion. An inflation device is used to expand the balloon and open the obstruction by fracturing and compressing plaque. Today, coronary stenting is an integral part of virtually all angioplasty procedures. The undeployed stent is mounted on a second balloon catheter that is passed over the guide wire to the area initially dilated. Balloon inflation expands and deploys the stent (Fig. 15-3). A high-pressure balloon catheter is then used to fully expand the stent. With continued improvements in devices it is increasingly common to insert and fully expand the stent using a single-balloon catheter without predilatation.

Figure 15-3 Performance of percutaneous coronary intervention: stent deployment.

After PCI and after removal of catheters, hemostasis has traditionally been achieved at the access site via manual compression once the activated clotting time has returned to baseline. Recently, the use of “closure devices” at the femoral arteriotomy site has gained popularity. In this circumstance, the femoral arteriotomy site is closed with either a suture or a collagen plug immediately after the procedure, thus providing immediate hemostasis in suitable patients and allowing earlier ambulation.

Adjunctive Pharmacologic Therapy

All patients undergoing PCI receive aspirin before the procedure, and the patient is then fully anticoagulated during the procedure to prevent thrombus formation on intravascular devices. Traditionally, heparin was used as the anticoagulant of choice with the addition of platelet glycoprotein (Gp) IIb/IIIa inhibitors to provide additional protection against thrombosis in patients presenting with acute coronary syndromes, in whom the risk of a periprocedural infarction and ischemic events is increased. More recently, bivalirudin has become the anticoagulant of choice. The incidence of periprocedural ischemic events with bivalirudin is comparable to heparin in combination with a platelet Gp IIb/IIIa inhibitor, but bivalirudin has the significant advantage of a short half-life with resulting reduction in access site bleeding complications.

A major problem with stent use has been thrombus formation on unendothelialized struts. The process of endothelialization is significantly inhibited with drug-eluting stents, and it may take months for struts to become completely covered. Late stent thrombosis (LST) occurring as long as a year after drug-eluting stent deployment is a major concern with currently available devices. Because of this concern, an oral antiplatelet program of aspirin and clopidogrel should be continued for 1 year after drug-eluting stent implantation to minimize this risk. Concerns about LST and potential bleeding complications from long-term dual antiplatelet therapy have tempered the early enthusiasm for the use of drug-eluting stents (see Fig. 15-1).

Outcomes with Percutaneous Coronary Intervention

With improved technology, the availability of improved stents, and greater operator experience, outcomes of PCI procedures have improved dramatically. With proper patient selection and when performed by experienced operators, procedural success—defined as reduction in the minimal lumen diameter at the lesion site to less than 20% with normal antegrade blood flow—can be expected in greater than 95% of patients. The risk of a complication such as dissection with vessel occlusion or vessel perforation is now a rarity in the catheterization laboratory. Although this practice is controversial, some operators have advocated performing these procedures without on-site surgical backup.

Operator experience is mandatory for these procedures to be performed safely. The American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for PCI recommend that PCI be performed only in institutions that do more than 400 PCI procedures per year and by operators who each perform more than 75 PCI procedures per year.

Restenosis had been a major limitation of PCI before the routine use of intracoronary stents. Balloon trauma to the vessel wall induces vascular cell hyperplasia, which may result in recurrence of arterial narrowing at 3 to 6 months. The use of bare-metal stents resulted in a significant reduction in restenosis rates. The development of drug-eluting stents—stents coated with a thin polymer carrying immunosuppressive or antiproliferative agents (i.e., sirolimus, paclitaxil) that are released over time to prevent the neointimal hyperplasia that can cause restenosis—has resulted in a further decrease in restenosis. The need for late repeat revascularization has decreased from 15% to 20% with bare-metal stents to 5% to 7% with drug-eluting stents. Given the risk of LST and the need for long-term anticoagulant therapy following implantation of a drug-eluting stent, it is important to individualize stent selection. For treatment of stenoses in larger diameter coronary arteries, it may not be necessary to use a drug-eluting stent.

With these advances, many patients who previously required CABG can now be effectively treated in the catheterization laboratory. Although it is still an effective means of treating patients with complex coronary disease, CABG is now necessary in a smaller percentage of patients.