Percutaneous Coronary and Structural Heart Disease Interventional Techniques

10 Percutaneous Coronary and Structural Heart Disease Interventional Techniques

The widespread use of percutaneous coronary and structural heart disease interventional techniques performed after diagnostic angiography for patients with ischemic and structural (e.g., valvular or atrial septal defects) heart disease is now commonplace. A companion book, the Interventional Cardiac Catheterization Handbook, expands on the concepts presented in this chapter and provides a more detailed foundation for indications, contraindications, and complications of interventional cardiology techniques. Table 10-1 lists diagnostic and therapeutic procedures performed in the catheterization laboratory.

Table 10-1 Diagnostic and Therapeutic Procedures in Cardiac Catheterization Laboratory

Diagnostic Procedures Therapeutic Procedures
Coronary angiography Angioplasty—balloon stents, DCA
Ventriculography Valvuloplasty
Hemodynamics Shunt closure
Shunt detection Thrombolysis
Ao and peripheral angio Coil embolization
Pulmonary angio Pericardiocentesis, window
Coronary hemodynamics Percutaneous valve Rx
Endomyocardial biopsy  

Ao, angio; DCA, directional coronary atherectomy; Rx, treatment.

Percutaneous Coronary Interventions

Coronary balloon angioplasty was first performed in 1977. Up to that time, coronary artery bypass graft (CABG) surgery was the only alternative to medical treatment of coronary artery disease. Coronary artery bypass graft surgery attaches a segment of leg vein, arm artery, and/or chest wall artery to the heart to detour blood around the narrowed portion (i.e., stenosis) of a coronary artery. Percutaneous transluminal coronary balloon angioplasty (with the introduction of stents, PTCA is now called PCI) provided an alternative to CABG. PCI selectively enlarged the narrowed portion of the artery without surgery by the insertion of a long thin balloon to open the blocked artery. Rarely used by themselves today, coronary balloons are now used to deliver coronary stents (metal meshlike stainless steel implants) and used with other devices such as cutters, grinders, lasers, and aspiration catheters to treat a wide variety of artery problems. These methods are collectively referred to as PCI. The nomenclature is informative:

Figure 10-1 shows how to perform PCI. A guiding catheter is seated in the coronary ostium. A thin, steerable guidewire is introduced into the coronary artery and positioned across the stenosis into the distal aspect of the artery. An angioplasty catheter, which is considerably smaller than the guiding catheter, is inserted through the guiding catheter and positioned (in the artery) across the stenotic area by tracking it over the guidewire. The balloon or stent is on the PCI catheter. When the balloon or stent is placed correctly within the area to be treated, the balloon on the PCI catheter is inflated several times for periods ranging from 10 to 30 seconds. The inflation and deflation of the balloon stent in the blocked artery restores blood flow to an area of the heart previously deprived by the stenosed artery. After stent implantation and if no complications occur, patients usually stay overnight in the hospital and are discharged the following morning. Patients can usually resume their normal routine within several days.

How Balloon Angioplasty Works

Several theories regarding the mechanisms of angioplasty have been proposed.

Mechanism of Stents

Stents scaffold the lumen and plaque open, holding back dissection flaps and stopping vessel recoil and re-narrowing of the lumen.

The indications, contraindications, and complications of PCI are listed in Table 10-2.

Table 10-2 Indications, Contraindications, and Complications of Percutaneous Coronary Intervention (PCI)

Indications for PCI

Contraindications for PCI

Complications Associated with PCI

Restenosis is the re-narrowing of the vessel after treatment by balloon and stent leading to recurrence of anginal symptoms. Restenosis is not considered a true complication but is an adverse event requiring retreatment or CABG. Restenosis is caused mostly by intimal hyperplasia and rarely by vessel recoil after stenting. Its incidence is approximately 10% after drug eluting stents. Typically, restenosis occurs in the initial 6 months after PCI. In-stent restenosis is less than 10% with drug-eluting stents. Stent thrombosis is different than restenosis and is a potentially catastrophic event that can lead to myocardial infarction (MI) or death. It occurs in approximately 1% to 2%, especially if dual antiplatelet therapy (i.e., aspirin and Plavix) is prematurely discontinued.


PCI equipment consists of three basic elements: the guiding catheter, the balloon-stent catheter, and the coronary guidewire (Fig. 10-2).

Guiding Catheter

A special large-lumen catheter is used to guide the coronary balloon catheter to the vessel that has the lesion to be dilated (Fig. 10-3). Compared with diagnostic catheters, guiding catheters have thinner walls and larger lumens, which allow contrast injections to be done while the balloon catheter is in place. The guiding catheters are stiffer than diagnostic catheters to provide support for advancing the balloon-stent catheters into the coronary artery. They respond differently to manipulation than diagnostic catheters. The guiding catheter tip is not tapered, occasionally blocking the ostium and causing pressure dampening while engaging the coronary ostium. A 6 F guiding catheter is generally used. Some catheters have relatively shorter and more flexible tips than other catheters, theoretically to decrease catheter-induced trauma. Others may have side holes to help maintain blood flow during PCI. Larger guiding catheters (7 F or 8 F) may be necessary for kissing balloons/stents, rotoblator burrs larger than 2 mm, and some cutting balloons. There are many different shapes of guiding catheters for different anatomic variations.

Functions of the Guiding Catheter

There are three major functions of a guiding catheter during PCI:

Balloon Catheters

Over-the-Wire (OTW) Angioplasty Percutaneous Coronary Intervention Systems

A standard OTW PCI catheter (Fig. 10-4) has a central lumen throughout the length of the catheter for the guidewire and a separate lumen for the balloon inflation. These catheters are approximately 145 to 155 cm long and can be used with long or short guidewires, usually 0.014 inch.

The advantages and limitations of OTW angioplasty balloon catheters are listed in Table 10-3. These catheters accept multiple guidewires, which allows for the exchanging of additional devices that may require stronger, stiffer guidewires. Maintenance of distal wire position beyond the target stenosis is paramount in coronary angioplasty. For OTW balloon catheters the guidewire can be extended to help maintain distal position while the balloon catheter is withdrawn completely over the guidewire to permit another balloon catheter to be exchanged and introduced over the same guidewire for additional dilations. A 300-cm exchange wire is also commonly used.

Table 10-3 Advantages and Limitations of Angioplasty Balloon Types

  Advantages Limitations
Over the wire Distal wire position Needs two people for exchange
  Distal port for pressure, contrast injection Accepts multiple guidewires
Rapid exchange (monorail) Ease of use
Single-operator system
Needs good guide support
  Enhanced visualization Blood loss at Y valve during exchanging
    Poor balloon tracking
Fixed wire Enhanced visualization Lack of through lumen
  Single-operator system Exchanging balloon requires access to distal lesions and complete removal of balloon
  Use with small guiding catheters Very low-profile PCI balloon

OTW angioplasty balloon catheters have few limitations. A primary operator and experienced personnel are required to perform catheter exchanges. Several different types of devices can be used to fix a 155-cm guidewire in place to permit OTW catheters to be exchanged without using a 300-cm guidewire. These devices are now rarely used and have included a wire entangler, a balloon trapper, and a magnet fixation system (see later).

Rapid-Exchange (Monorail) Percutaneous Coronary Intervention Catheters

Rapid-exchange balloon catheters are the most popular catheters used today and were developed to allow a single operator to exchange the PCI catheters unassisted. This rapid exchange catheter differs from over the wire PCI catheters in that only a variable length of the shaft has two lumens (Fig. 10-5, A). One lumen is for balloon inflation and the other, which extends through only a portion of the catheter shaft, houses the guidewire. Because only a limited portion of the balloon requires dual lumens, the catheter shafts can be made smaller than over the wire systems.

Rapid-exchange balloon catheters address certain inherent limitations of OTW systems. First, OTW balloon exchanges requiring extension of the distal wire or a long wire are unnecessary because the rapid-exchange portion of the catheter is short. Second, a single operator can use rapid-exchange balloon catheters without the aid of other assistants to maintain distal guidewire position or facilitate balloon navigation.

Monorail catheters also have limitations, including the need for excellent guiding catheter support and more operator skill for the complexity in manipulation of the guidewire, balloon catheter, and guiding catheter. Blood loss during removal of the monorail balloon catheter at the rotating hemostatic valve can be a problem but can also be reduced with better technique and valved connectors.

Fixed-Wire Angioplasty Balloon Catheters

The fixed-wire catheter is rarely used today and has the balloon mounted on the wire with a distal flexible steering tip (Fig. 10-5, B). The proximal end of the catheter consists of a single, nonremovable port connected to a hollow metal tube (hypotube). A core wire extends from the hypotube to the end of the distal steerable tip. This assembly is coated with a thin plastic shaft that enhances flexibility. Fixed-wire balloons have only one enclosed lumen for balloon inflation.

The advantages and limitations of fixed-wire angioplasty balloon catheters are listed in Table 10-2. The small shaft size of the single-lumen design provides excellent coronary visualization. Because the balloon is mounted on the distal guidewire, the device can easily be used by a single operator. Fixed-wire balloon catheters are particularly useful for distal lesions, subtotal stenoses, and lesions located in tortuous small vasculature.

Fixed-wire catheters have significant limitations. These catheters lack the inherent safety advantage of OTW and rapid-exchange systems because the balloon is mounted on a guidewire. To exchange this catheter for a different balloon size, the catheter is removed completely, and the lesion recrossed with a different size catheter. Alternately, the catheter remains across the lesion, and a second guidewire is advanced to secure access to the lesions. The fixed-wire balloon can be withdrawn and the procedure completed with standard techniques. A narrowed or dissected lesion may not permit balloon advancement or even may close the vessel. The lack of a distal lumen prevents measurement of distal pressure or injection of contrast media to evaluate distal vessel runoff. This catheter is not commonly used in clinical practice.

Jun 5, 2016 | Posted by in CARDIAC SURGERY | Comments Off on Percutaneous Coronary and Structural Heart Disease Interventional Techniques

Full access? Get Clinical Tree

Get Clinical Tree app for offline access