PCI in the calcified lesion
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
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Challenges of Calcified Lesions
- The presence of coronary calcification reduces the compliance of the vessel, and may predispose to dissections at calcified plaque–normal wall interface after balloon angioplasty
- The presence of coronary calcification also reduces the ability to cross chronic total occlusions, and, in severely calcified lesions, stent strut expansion is inversely correlated with the circumferential arc of calcium. [1]
- The presence of extensive coronary calcification poses unique challenges for PCI as calcium in the vessel wall leads to irregular and inflexible lumens, and makes the delivery of guidewires, balloons, and stents much more challenging.
- Extensive coronary calcification also renders the vessel wall rigid, necessitating higher balloon inflation pressures to obtain complete stent expansion, and, on occasion, leading to “undilatable” lesions that resist any achievable balloon expansion pressure.
Calcification in Saphenous Vein Grafts (SVGs)
Calcifications noted within SVGs are generally within the reference vessel wall rather than within the lesion, and are associated with older graft age, insulin–dependent diabetics, and smoking. [2]
Angiographic Evaluation
Coronary artery calcium is an important marker for coronary atherosclerosis. Conventional coronary angiography has limited sensitivity for the detection of smaller amounts of calcium, and only moderately sensitive for the detection of extensive lesion calcium (sensitivity 60% and 85% for three- and four-quadrant calcium, respectively). [3]
Treatment
There are a variety of diagnostic and treatment options for calcified lesions, but better early outcomes may be achieved by using a multi-device interventional strategy.
Intravascular Ultrasound (IVUS)
Intravascular Ultrasound is a medical imaging methodology using a specially designed catheter with a miniaturized ultrasound probe attached to the distal end the catheter. The proximal end of the catheter is attached to computerized ultrasound equipment. It allows the application of ultrasound technology to see from inside blood vessels out through the surrounding blood column, visualizing the endothelium (inner wall) of blood vessels in living individuals. IVUS is used in the coronary arteries to determine the amount of atheromatous plaque built up at any particular point in the epicardial coronary artery.
While coronary angiography by fluroscopy is limited in its detection and severity assessment of coronary calcification, IVUS can assess the extent of calcification and may be particularly useful for instances when the reason for poor balloon expansion is uncertain. Although this approach has its advantages over angiography, heavy involvement of superficial, sub-endothelial calcification may require rotational atherectomy.
Rotational Atherectomy
Rotational atherectomy is a minimally invasive method of removing plaque and blockage from an artery in the body and subsequently widening arteries narrowed by arterial disease. It falls under the umbrella category of percutaneous revascularization, which refers to a variety of methods normally used in coronary arteries to restore circulation to the lower extremities. Unlike angioplasty and stents of blocked arteries that simply push blockages aside into the wall of the artery, atherectomy involves inserting a thin catheter with a scraping blade into the artery. The plaque buildups are removed, opening the artery and restoring normal blood flow.
Rotational atherectomy creates micro-fractures, removes calcified plaque, and increases vessel compliance, thereby facilitating PTCA. Despite its usefulness in treating calcified lesions, certain precautions should be taken. In an effort to limit the risk of vessel laceration, smaller diameter [[Burr (cutter)|burrs] are now recommended. A general guideline to use is that the initial burr:luminal ratio should be 1:2. Additional caution should be taken when a coronary dissection is present, as rotational atherectomy may propagate the dissection.
- Rotational atherectomy in severe lesion calcification: Rotational atherectomy is the preferred pretreatment method in patients with severe lesion calcification, particularly ostial lesions, and facilitates the delivery and expansion of coronary stents by creating microdissection planes within the fibrocalcific plaque. Yet even with these contemporary methods, the presence of moderate or severe coronary calcification is associated with reduced procedural success and higher complication rates[4], including stent dislodgement.
- Rotational atherectomy in mild-moderate calcifications: In less severely calcified lesion, no differences in restenosis rates were found after paclitaxel-eluting stent implantation in calcified and non calcified vessels. [5]
References
- ↑ Vavuranakis M, Toutouzas K, Stefanadis C, Chrisohou C, Markou D, Toutouzas P (2001). "Stent deployment in calcified lesions: can we overcome calcific restraint with high-pressure balloon inflations?". Catheter Cardiovasc Interv. 52 (2): 164–72. PMID 11170322. Unknown parameter
|month=ignored (help) - ↑ Castagna MT, Mintz GS, Ohlmann P; et al. (2005). "Incidence, location, magnitude, and clinical correlates of saphenous vein graft calcification: an intravascular ultrasound and angiographic study". Circulation. 111 (9): 1148–52. doi:10.1161/01.CIR.0000157160.69812.55. PMID 15723972. Unknown parameter
|month=ignored (help) - ↑ Mintz GS, Popma JJ, Pichard AD; et al. (1995). "Patterns of calcification in coronary artery disease. A statistical analysis of intravascular ultrasound and coronary angiography in 1155 lesions". Circulation. 91 (7): 1959–65. PMID 7895353. Unknown parameter
|month=ignored (help) - ↑ Wilensky RL, Selzer F, Johnston J; et al. (2002). "Relation of percutaneous coronary intervention of complex lesions to clinical outcomes (from the NHLBI Dynamic Registry)". Am. J. Cardiol. 90 (3): 216–21. PMID 12127606. Unknown parameter
|month=ignored (help) - ↑ Moussa I, Ellis SG, Jones M; et al. (2005). "Impact of coronary culprit lesion calcium in patients undergoing paclitaxel-eluting stent implantation (a TAXUS-IV sub study)". Am. J. Cardiol. 96 (9): 1242–7. doi:10.1016/j.amjcard.2005.06.064. PMID 16253590. Unknown parameter
|month=ignored (help)