Unstable Angina In a Patient With a Single Sequential Saphenous Vein Bypass Graft <br />
Supplying the Entire Coronary Circulation

Case Description. A 72-year-old man was admitted to our institution with unstable angina pectoris. In 1980, he underwent single-vessel coronary artery bypass graft surgery (CABG) receiving a saphenous vein bypass graft (SVG) to the left anterior descending coronary artery (LAD). In April 2000, one year prior to the current presentation, he had a non-ST elevation myocardial infarction (MI). Coronary angiography revealed severe left main (LM) stenosis and an occluded LAD at its origin. The right coronary artery (RCA) had severe disease. The SVG to LAD had multiple areas of high-grade stenosis. Due to clinical instability, the patient was referred for emergency re-do CABG. After induction of anesthesia, the patient had ventricular fibrillation, requiring CPR and multiple defibrillation shocks. The patient received an emergency single sequential SVG to the LAD, to a major distal obtuse marginal (OM) branch and to the RCA. Following his second surgical revascularization, he did well, until the past two months, when he developed recurrent angina pectoris. On the day of admission, he had an episode of severe chest pain. There was no evidence of myonecrosis by serial CPK-MB and troponin levels. Despite treatment with intravenous heparin and tirofiban, the patient had recurrent angina associated with dynamic lateral ST segment depression. Past medical history was significant for hyperlipidemia. Current medications included intravenous heparin, tirofiban and nitroglycerin, and oral aspirin, metoprolol, ramipril and atorvastatin. Physical examination was notable for a temperature of 37.4 ºC, a regular heart rate of 66 beats per minute, blood pressure of 120/70 mmHg, a respiratory rate of 16 breaths per minute, a height of 175 cm and weight of 93 kg. The neck veins were not distended and there were no carotid bruits. The heart sounds were normal with an S4 gallop and no murmurs. The lungs were clear. Abdominal and neurological examination were normal. The peripheral pulses were normal. Diagnostic coronary angiography revealed severe (95%) distal left main coronary artery stenosis (Figure 1A) with diffuse LM calcification and mid-vessel (50–60%) disease. The LAD was densely calcified and occluded at its origin. The left circumflex (LCx) had diffuse proximal 50% narrowing and a large distal OM branch that was grafted. During left coronary angiography, flow was seen from the distal OM branch entering the sequential SVG with anterograde filling to the RCA and retrograde filling to the LAD (Figure 1B). The RCA was occluded in its mid portion. The SVG to LAD (first CABG) was occluded at its ostium. The sequential SVG to LAD, OM and RCA (second CABG) had a 95% aorto-ostial stenosis with diminished flow (Figure 2). Patient management. In light of the patient’s refractory unstable anginal symptoms and his two prior CABG surgeries, catheter-based intervention of the SVG ostium was performed. A 9.5 French (Fr) 40 cc intraaortic balloon pump was placed prophylactically via the left femoral artery. Tirofiban infusion was continued, and intravenous heparin was given to achieve an ACT of 250 seconds. The SVG was cannulated using an 8 Fr JR 3.5 with side holes guiding catheter. A 0.014´´ S’port coronary guidewire (Advanced Cardiovascular Systems, Temecula, California) was advanced into the body of the SVG. The ostial lesion was dilated with a 3.5 x 20 mm Predator angioplasty balloon (Cordis, Warren, New Jersey) (Figure 3). The ostial lesion was stented with a 4.0 x 15 mm S-670 stent (Medtronic AVE, Santa Rosa, California) and was post-dilated to 22 atmospheres with a 4.5 x 9 mm Chubby angioplasty balloon (Boston Scientific/Scimed, Maple Grove, Minnesota). This resulted in an excellent angiographic result with TIMI grade III flow into this sequential graft (Figures 4A and 4B). Post-procedural medications included tirofiban, aspirin, clopidogrel, ramipril, metoprolol and atorvastatin. The intraaortic balloon pump was removed later the same day. Following the procedure, he had an uncomplicated course and was discharged from the hospital two days later. How Would You Manage This Case? Lowell F. Satler, MD Washington Hospital Center, Washington, D.C. In this case presentation, the authors describe a complicated 72-year-old male who had a previous CABG with a second operation. His clinical presentation of an acute coronary syndrome was related to a severe ostial stenosis in a single remaining conduit (SVG to LAD to M1 to RCA). The authors proceeded with PTCA of this high-risk subset and completed it successfully. The strategy of the authors was really the only therapeutic option. The patient had undergone two previous operations. A third operation would have had an extremely high morbidity and mortality. Due to the focal nature of the proximal lesion, easy access to treating the culprit lesion would not be a problem. The authors then prepared this high-risk patient appropriately, anticipating the potential for hemodynamic collapse with the use of a prophylactic intra-aortic balloon pump. Although one typically now considers treatment of SVGs with distal protection, the only available distal protection system is the Percusurge distal occlusion balloon, which can be difficult to use for aorto-ostial disease for 2 reasons: 1) placing a stent at the ostium of an occluded vessel is difficult enough before of obscured landmarks; with the distal occlusion balloon inflated, contrast injection to outline the ostium is no longer available, thereby increasing stent positioning. 2) Since forward flow is not present with the occlsion balloon inflated, embolized debris during stent deployment of an ostial lesion lesion could retrogradely move into the aorta. Ultimately, the lesion was successfully predilated and then stented. The only difference in the approach to treatment with this ostial SVG lesion would have been to consider the use of a cutting balloon for plaque modfication. Cutting balloons have several advantages for treating ostial disease. First is the lack of a the “watermelon seeding” phenomenon, when dealing with an often rigid ostial plaque due to presence of the athertomes. In addition, it is not well appreciated that the cutting balloon can exert very high forces during dilation, particularly suitable for ostial lesions that are either fibrotic or calcified. The atherotome blades can exert as much as 150,000 times the amount of pressure as an ordinary balloon (in figure above). James P. Zidar, MD Duke University, Durham, North Carolina This type of case is becoming more common, i.e., an elderly patient with SVG disease after multiple coronary bypass procedures. The ostial location of the stenosis is also challenging. It is unfortunate that this patient had two prior bypass surgeries and had not received a LIMA graft, the one durable conduit that provides a mortality benefit. I agree with much of the strategy taken by the operators, which included the prophylactic intraaortic balloon pump followed by PCI and stenting of the SVG ostium. As I read the narrative, I did not see a description of the patient’s left ventricular function. In general, I reserve the use of the intraaortic balloon pump to patients with significant left ventricular dysfunction (EF