MODULE 1 LESSON 4 LESIONS ASSOCIATED WITH CAD|2023/24 UPDATE|GRADED A+

Introduction When the physician considers a percutaneous coronary intervention (PCI), lesion and patient attributes should be evaluated, as well as the relevant coronary artery anatomy. Attributes specific to each case will determine how a PCI should be conducted This lesson focuses on the American College of Cardiology/American Heart Association (AHA/ACC) lesion classification system By classifying lesions into specific categories, interventional physicians can anticipate success and complication rates when treating the patient. Lesions can be classified based on specific characteristics Concentric and eccentric Vessel tortuosity Ostial disease Bifurcation disease Small vessel disease Multivessel and diffuse disease Chronic total occlusion In-stent restenosis What is a lesion? A coronary artery lesion (stenosis) is a narrowing or obstruction of the artery that causes restricted blood flow to the myocardium Lesions can starve the myocardium of oxygen and vital nutrients, a condition known as ischemia ACC/AHA Classification of Coronary Lesions Coronary lesions are classified as type A, B, or C based on the ACC/AHA task force classification In 1988, this joint task force published the type A, B, and C lesion tables to help physicians estimate procedural success and risk based on the presence or absence of specific lesion characteristics Type A Characteristics -Success Rate and Risk: high (85%) and low risk of abrupt vessel closure -Length: 10 mm -Angulation: 45 degrees -Contour: Smooth -Calcification: Nill or litle -Thrombus: Not present -Eccentricity: concentric Location -Ostial or Not: non-ostial -Tortuosity or Proximal Segment: nill or mild -Major Side Branch Involvement: absent Type B Characteristics -Success Rate and Risk: moderate (60-85%) and moderate risk of abrupt vessel closure -Length: 10-22 mm -Angulation: 45-90 degrees -Contour: Irregular -Calcification: Moderate or heavy -Thrombus: Present -Total Occlusion: 3 months -Eccentricity: eccentric Location -Ostial or Not: ostial -Tortuosity or Proximal Segment: moderate -Major Side Branch Involvement: bifurcation lesion needing guidewire Type C Characteristics -Success Rate and Risk: low (60%) and high risk of abrupt vessel closure -Length: 20 mm -Angulation: 90 degrees or more -Total Occlusion: 3 months old Location -Tortuosity or Proximal Segment: severe -Major Side Branch Involvement: inability to protect major side branch Other: degenerated vein graft with friable or brittle lesions Concentric and Eccentric Lesions There are two types of cross-sectional, luminal lesion shapes: concentric and eccentric The variation in distribution of atherosclerotic plaque along the internal elastic membrane of coronary arteries causes these lesion shapes Concentric Lesions Typically classified as Type A because they are characterized by the even distribution of disease tissue across the entire circumference of the arterial lumen Treatment Considerations: can be treated with a fairly simple procedure; includes utilizing a semi-compliant balloon to dilate the opening, followed by stent placement Eccentric Lesions Occur when atherosclerotic plaque fails to involve the entire coronary artery lumen circumference, leaving a variable arc of disease-free wall and other portions of the wall with more extensive disease These lesions can be easily missed if multiple/orthogonal views are not used during angiography. For example, when an artery is viewed from one direction, it may appear only mildly abnormal, e.g. 30% narrowed. When viewed from another angle, the vessel demonstrates more significant narrowing of 70% Eccentric lesions are considered Type B lesions and may be more difficult to treat Concentric and Eccentric Lesions Treatment Considerations Dilate the opening with a semi-compliant balloon first, then stent However, because wire navigation may be more difficult through an eccentric lesion than a concentric lesion, a physician may use a wire with more stiffness and more torque control, or additional devices (e.g. balloons, support catheters) to provide more pushability and backup support Also, when dilating an eccentric lesion, physicians must be careful not to dissect or perforate the "healthy" side of the wall while compressing the sides with plaque Vessel Tortuosity Lesions occurring in a tortuous artery are considered Type B or C lesions, depending on their degree of tortuosity Tortuosity is a widely observed anomaly affecting a range of vessels, from large arteries and veins to small arterioles and venules Tortuosity can occur in different forms such as curving, curling, angulation, twisting, and kinking of the vessel As with most lesion types, tortuous arteries are linked to aging, atherosclerosis, hypertension, genetic defects, and diabetes mellitus. The specific mechanisms of tortuous vessel formation and development are not fully understood. Vessel Tortuosity Treatment Considerations a physician may consider utilizing a supportive guide catheter to assist in pushing devices; flexible yet supportive wire to navigate past a stenotic area in a tortuous vessel; low-profile balloon with a supportive catheter delivery system; low profile stent that is also highly flexible to navigate through tortuous areas and stenosis Ostial Lesions Occur at the opening of an artery and are considered Type B or C lesions, depending on the location, size, and importance of the artery. Lesions are considered ostial in nature if they arise within 3 mm of the origin of the vessel or branch One of the first signs of an ostial stenosis is dampening of the arterial pressure when the guide catheter engages the ostium. Dampening means a drop in the amplitude of the pressure wave. Typically, this is due to blocked blood flow Ostial Lesions Treatment Considerations The treatment of ostial coronary lesions may be technically challenging. If the lesion occurs in the ostium of the RCA or LM, treatment of these lesions can be performed safely if care is performed when manipulating the guide catheter and monitoring hemodynamics The physician conducting the procedure must ensure the guide catheter does not deep-seat and disrupt the ostial lesion Upsizing the guide catheter to a 7 or 8 Fr is one tactic that may prevent the guide from slipping into the ostium of the LM or RCA. A guide with side holes may also be selected to maintain blood flow. Ostial lesions occurring in an OM or diagonal may require more supportive and torquable wires, or guide catheter manipulations to assist in passing the stenosis When a balloon and stent are deployed near the ostium, the stent is allowed to slightly protrude proximally (102 mm) past the ostial opening in order to make sure the entire lesion is treated