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Table 2
Characteristics of Type A, B, and C Lesions
| Lesion-Specific Characteristics
|
| Type A lesions (minimally complex)
|
| Discrete (length <10 mm)
|
| Concentric
|
| Readily accessible
|
| Nonangulated segment (<45°)
|
| Smooth contour
|
| Little or no calcification
|
| Less than totally occlusive
|
| Not ostial in location
|
| No major side branch involvement
|
| Absence of thrombus
|
| Type B lesions (moderately complex)∗
|
| Tubular (length 10 to 20 mm)
|
| Eccentric
|
| Moderate tortuosity of proximal segment
|
| Moderately angulated segment (>45°, <90°)
|
| Irregular contour
|
| Moderate or heavy calcification
|
| Total occlusions <3 mo old
|
| Ostial in location
|
| Bifurcation lesions requiring double guide wires
|
| Some thrombus present
|
| Type C lesions (severely complex)
|
| Diffuse (length >2 cm)
|
| Excessive tortuosity of proximal segment
|
| Extremely angulated segments >90°
|
| Total occlusions >3 mo old and/or bridging collaterals
|
| Inability to protect major side branches
|
| Degenerated vein grafts with friable lesions
|
- ∗ Although the risk of abrupt vessel closure may be moderately high with Type B lesions, the likelihood of a major complication may be low in certain instances such as in the dilation of total occlusions <3 mo old or when abundant collateral channels supply the distal vessel.
|