Coronary Stenting of the Left Main Artery
by Alan
Kogan, M.D.
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Coronary stent insertions have become a frequent procedure in today’s cath labs, accounting for up to 60% of angioplasty volume in larger medical centers. Since becoming FDA-approved in the summer of 1994, coronary stents have increased the efficacy of angioplasties by decreasing morbidity and mortality by one-third and restenosis by almost one-half.1
What isn’t so common is the use of coronary stents in more advanced disease states. Previously, critical stenosis of the left main coronary artery automatically required coronary bypass surgery—a risky and taxing undertaking for any patient, let alone those at high risk or who have already undergone one or more prior cardiac surgeries. For such patients, coronary stenting may provide a safer alternative. Because of his prior bypass surgery and stroke, A.S. was an ideal candidate for coronary stent insertion into the left main coronary artery. (See Case Study)
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Case
Study
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Patient: A.S., a 65-year-old male from Buffalo Grove, Ill. History: Coronary artery bypass seven years earlier; recurrent angina Symptoms: Class IV angina Tests: Angiogram Diagnosis: Critical narrowing of left main coronary artery and occlusion of LIMA graft to the left anterior descending artery Treatment: Stent insertion in the left main coronary artery |
Angiography had revealed that the left internal mammary bypass to his left anterior descending coronary artery was closed, but that the vein bypass to his left circumflex coronary artery was still patent. (See Figure 1.)
Figure
1:
Angiogram of stenotic left main coronary artery
Because of the increased risk of dilating and stenting the left main coronary artery, the patient was put on an intra-aortic balloon pump for hemodynamic support during the procedure.
Percutaneous cardiopulmonary support (PCPS), a cath lab technique similar to heart-lung bypass, may also be required for the most unstable patients.
As with other stent procedures, the artery must first be dilated. Although a balloon angioplasty was used in this case, a Rotoblator® or laser ablation may also be used to debulk the artery and maximize the opening, depending on the nature of the individual blockage. It is therefore imperative that the cardiologist and support team performing the procedure are well-experienced in all of the latest debulking techniques.
After the artery was pre-dilated, the stent was delivered and compressed into the walls of the artery using a special high pressure balloon system. (See Figure 2.) Then, in order to ensure that the stent was perfectly deployed and that there was no collateral vascular damage, an intravascular ultrasound of the stented coronary artery was performed. In addition, ticlopidine and aspirin were prescribed to pre-vent intra-stent thrombosis. A.S. was discharged within 48 hours of admission. Within six to eight weeks, new endothelial tissue had overgrown the stent, separating it from circulating blood elements. The patient quickly resumed his vigorous exercise program of one hour of aerobic activity daily.
Figure
2:
Angiogram of stented left main coronary artery
One year later, he remains angina free, has required no further interventional procedures, has completed 14 minutes on a treadmill stress test, and has continued to see his primary care physician. Success stories such as this are increasing. The current success rate for coronary stenting of the left main coronary artery is 95%2. In addition to lower mortality and morbidity rates than repeat bypass surgery, coronary stent insertion in the left main coronary artery greatly reduces patient pain and discomfort as well as recovery time, thus enhancing patient satis-faction and returning the patient to the care of his or her primary physician more quickly.
1 Rodriguez AE, Santaera O, Larribau M, et al., Coronary stenting decreases restenosis in lesions with early loss in luminal diameter 24 hours after successful PTCA. Circulation, Mar 1 1995, 91(5), p1397-1402.
2 Macaya C, Alfonso F, Iniguez A, et al. Stenting for elastic recoil during cornary angioplasty of the left main coronary artery. Am J Cardiol, Jul 1 1992, 70(1), p105-7.
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