Table 78.1 lists proposed curricula to independence and activity thereafter (12,13,14,15,16). Minimum records are acceptable, but with a history of a more active training period and support by an experienced interventional environment (peers and team). The mortality rates decrease with the patient volume of a center, plateauing at about 600 yearly cases (17). The individual operator volume appears to affect complications less conspicuously, but further improvement beyond 75 cases per year can be demonstrated, particularly in high-risk patients (18).

At least one person, using sterile garment, is advisable to assist the primary operator with catheter exchanges and manipulations. An additional person has to be on hand to fetch material, tend to the patient, and summon help in case of need. A single physician suffices in general, but an additional physician with advanced resuscitation skills must be available within minutes and a spare angioplasty operator within the hour. The
unpredictable nature of coronary artery disease in general and of freshly dilated coronary arteries in particular requires on-call 24-hour service.

Catheterization laboratories have to meet high standards to be fit for interventional cardiology. Biplane fluoroscopy is helpful but less important than digital image enhancement and radiation-thrifty flat panel technology. A spare unit providing angulated fluoroscopy should be available for breakdowns during a critical phase of a case.

The storage medium is digital. Exchange is possible via data lines or various recordable disks. Still-frame hard copies are useful for the hospital chart, the patient, and the referring physician.

Pressure curves and electrocardiographic (ECG) tracings have to be displayed throughout the case. Pertinent ECG changes
and symptoms, such as ST-segment alterations, malignant arrhythmia, and chest pain during balloon inflation, should be documented. A device to measure the activated clotting time is welcome but not indispensable.

A modern balloon catheter comes in a variety of diameters and lengths, is sleek, has a slippery coating inside (minimal guidewire friction) and outside, has a low crossing profile and good “trackability” and “pushability,” inflates and deflates rapidly, and tolerates pressures up to 30 bar with contained expansion (compliance).

The coronary guiding catheters are derived from diagnostic catheters in terms of shapes and materials. Their walls are thinner but still torque true and kink resistant. Diameters of guiding catheters currently range from 5 to 10 Fr (1.7 to 3.3 mm outer diameter).

The guidewire has to transmit torque reliably from the stiff outside end to the floppy tip. It should provide minimal resistance during advancement but optimal support for the catheters introduced over it. A diameter of 0.014 in (0.36 mm) is standard. Hydrophilic coating reduces friction and guarantees easy advancement, but it harbors the risk of occult perforations of thin-walled healthy peripheral coronary arteries with subsequent hemopericardium. The wire tip may be equipped with a Doppler ultrasound crystal, a pressure transducer, a ball tip, a radiofrequency transmitter, or an optical lens for angioscopic tissue analysis or laser transmission.

An adjustable Y connector prevents leaking and permits contrast medium injections and pressure monitoring through a single arterial access after the introduction of the guidewire and the balloon catheter into the guiding catheter. A wire torquer ensures controlled rotation of the wire tip. An indeflator with an incorporated pressure gauge affords effortless inflations (in fact, a misnomer for fillings with diluted contrast medium) and maintains constant negative pressure in the balloon lumen of the catheter while the balloon is not inflated.

It is important but difficult to determine what makes a lesion significant enough to warrant PCI (43). There are different means to assess the functional significance of a stenosis. Clinical tests (e.g., exercise ECG, stress echocardiography, scintigraphy) are not very sensitive and lack specificity for the individual lesion. Quantitative coronary angiography of the lesion is imprecise almost to the degree of visual estimates (44). Intravascular ultrasound (45), flow velocity (46) or pressure measurements (47), and angioscopy (48) are more objective, but they engender additional costs and risks and have failed to gain widespread acceptance.

To restrict indications to hemodynamically significant lesions may be misguided. The ultimate threat is not the occurrence of angina (affecting only quality of life), but rather the thrombotic occlusion of the vessel, causing infarction and death. Although an individual mild stenosis has a low infarct potential, the hazard is clearly there. Besides, collaterals are rare with mild lesions, a finding that renders their occlusion particularly dangerous. Consequently, restricting PCI to flow-limiting lesions neglects its potential for plaque sealing (i.e., significantly reducing the risk of subsequent thrombotic occlusion thanks to the neoendothelium overgrowing the PCI-inflicted inner wound) (49,50). Such an effect is safely assumed based on the event-free long-term course regularly observed after uncomplicated balloon angioplasty. Restenosis after PCI for mild lesions is rare and is highly unlikely to produce infarction because of the nature of the renarrowing (smooth neoendothelium rather than rupture-prone atherosclerotic plaque). Nonetheless, the hypothesis has not been prospectively validated and may be invalidated by the use of a stent (small but significant risk of late stent thrombosis). Methods to elucidate the vulnerability of a plaque seem called for (Table 78.5) (51,52) but they provide merely a snapshot assessment. A vulnerable plaque means instability and calls for action. A stable plaque is not
particularly meaningful because it may become unstable at any time, perhaps even by the touch of the investigational device. Hence, PCI after such assessment will be the rule, rendering the assessment practically moot. Plaque passivation with statins (53) is a proved and ubiquitously applicable alternative or complement to plaque sealing by balloon angioplasty. The latter is attractive solely as an ad hoc procedure for an angiographically detected mild lesion at a strategically important site (proximal in a large vessel), and it remains clinically unproved (54).