Ann Thorac Surg 2006;82:1521-1523
© 2006 The Society of Thoracic Surgeons
Case Reports
Aortocoronary Shunting During Off-Pump Coronary Artery Bypass Surgery as Acute Reperfusion Strategy in ST-Elevation Myocardial Infarction
Parwis Massoudy, MDa,*,
Matthias Thielmann, MDa,
Andras Szabo, MDa,
Ivan Aleksic, MDa,
Eva Kottenberg-Assenmacher, MDb,
Jenno Szolnoki, MDc,
Heinz Jakob, MDa
a Department of Thoracic and Cardiovascular Surgery, West German Heart Center Essen, Essen, Germany
b Department of Anesthesiology and Intensive Care Medicine, University Hospital Essen, Essen, Germany
c Department of Cardiac Surgery, University Hospital Szeged, Szeged, Hungary
Accepted for publication February 2, 2006.
* Address correspondence to Dr Massoudy, West German Heart Center Essen, University Hospital, Department of Thoracic and Cardiovascular Surgery, Hufelandstr. 55, Essen, 45147 Germany (Email: parwis.massoudy{at}uni-essen.de).
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Abstract
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We report the case of a 43-year-old patient with acute ST-segment elevation anterior myocardial infarction who underwent off-pump coronary artery bypass grafting. To reduce the duration of ongoing myocardial ischemia, acute reperfusion of the infarcted coronary artery was achieved using an aortocoronary shunt, thereby perfusing the occluded left anterior descending artery. Under the protection of the aortocoronary shunt, the left internal thoracic artery was harvested and was thereafter anastomosed to the left anterior descending artery. The patient had an uneventful postoperative recovery.
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Introduction
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Coronary artery bypass grafting in acute myocardial infarction is known to be performed at a considerably increased perioperative risk. Mortality depends on the timing after transmural infarction. In a large retrospective study, investigating over 30,000 patients having undergone coronary artery bypass grafting after transmural myocardial infarction, perioperative mortality was described to be highest (14.2%) when coronary artery bypass grafting was performed within the first 6 hours after the ischemic event. When coronary artery bypass grafting was delayed for 4 to 7 days, perioperative mortality was reduced to 3.8% and could further be reduced when the delay was 8 to 14 days (2.9%) [1]. On the other hand, if the patient is at acute risk and the myocardium can be salvaged, quick reperfusion of the infarcted vessel is warranted. When reperfusion of an occluded coronary artery occurred at 40 minutes, transmyocardial necrosis was reported to be 38 ± 4%. When reperfusion occurred at 6 hours, transmyocardial necrosis was reported to be 71 ± 7% [2].
A 43-year-old man with a history of arterial hypertension and hyperlipidemia presented with an acute anterior myocardial infarction. He had suffered an acute anterior myocardial infarction 4 months earlier. A high-grade proximal stenosis of the left anterior descending (LAD) artery had been detected in coronary angiography and was treated with implantation of a bare metal stent. Then he underwent routine follow-up coronary angiography 4 months later. Because of an in-stent re-stenosis in the proximal LAD, a drug-eluting stent (Paclitaxel-eluting coronary stent, TAXUS, Boston Scientific, Ratingen, Germany) was implanted. Within 1 hour the patient complained about acute chest pain and electrocardiographic signs of anterior myocardial infarction with ST-segment elevation in I, II, and aVL. He was now registered for emergency coronary artery bypass grafting.
His current medical history consisted of enalapiril and metoprolol for his arterial hypertension, and simvastatin for his hyperlipidemia. He was immediately transferred to the cardiac surgical center under continuous perfusion with heparin, nitroglycerin, oral clopidogrel, and diazepam, and with buprenorphine for pain relief.
The electrocardiogram showed ST-segment elevation in leads I, II, avL and in the precordial leads V1–V4. Reversed image ST-segment depression was observed in leads III, avF, and the precordial leads V5 and V6. Preparative cardiac troponin I was not yet elevated (0.02 ng/mL) on arrival, and myoglobin was elevated to 140 µg/L (reference, < 51 µg/L).
He was directly transferred to the operating room and arrived within 3 hours after the onset of chest pain. The performance of an off-pump coronary artery bypass grafting procedure and the implantation of an aortocoronary shunt to terminate ongoing ischemia was discussed with the patient and his informed consent was obtained. A prophylactic intraaortic balloon pump was installed. The chest was opened and the LAD artery was exposed. Considerable hypokinesia of the anterior wall of the heart was visible. The LAD was stabilized in the mid-vessel region. There was almost no antegrade flow after opening of the vessel. Vessel lumen was 1.5 mm. An aortocoronary shunt (Quickflow, Medtronic, MN) was implanted. The aortocoronary shunt consists of a proximal end, which is placed into the ascending aorta like a regular cardioplegic cannula. It has four coronary arms that differ in size (Fig 1). The distal end was placed into the LAD and secured with a 6-0 monofilament suture (Fig 2). Almost instantly a slow but steady decline of ST-segment elevation could be observed and there was improvement of the hypokinesia of the anterior wall. The left internal thoracic artery was harvested and thereafter anastomosed to the LAD without removing the shunt until the last stitch had been made. Graft flow was determined using transit time flow measurement (Fig 3). Surgery was uneventful and the patient was transferred to the intensive care unit with mild catecholamine support and with the aortic balloon pump. He was extubated 8 hours later, free from catecholamine support; the balloon pump was weaned and was removed on postoperative day 2. Maximum postoperative cardiac troponin I was 31.8 ng/mL (reference, 0–0.1 ng/mL). Maximum postoperative levels of myoglobin and creatinkinase were 1,500 µg/L (reference, <51 µg/L) and 1,501 U/L (reference, 38–174 U/L), respectively. On postoperative day 3, before the patient was transferred to his referring cardiologist, cardiac troponin I had fallen to 7.6 ng/mL.
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Fig 3. Transit time flow determination of left internal thoracic artery graft to the left anterior descending artery.
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Comment
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The ST-segment elevation myocardial infarction is induced by complete occlusion of an epicardial coronary artery. After 3 to 6 hours of ischemia the possibility of salvaging the myocardial tissue from eventual transmural infarction dramatically decreases, depending on factors such as collateral blood flow. Starting from the subendocardial layer, the development of transmural necrosis was described to be 57 ± 7% at 3 hours and 85 ± 2% at 24 hours after myocardial infarction [2]. However even late reperfusion after more than 12 hours subsequent to an ischemic event was reported to be of benefit for patients with acute myocardial infarction treated with balloon angioplasty or stent implantation [3]. When coronary artery bypass grafting is performed in cases of acute myocardial infarction, aortocoronary shunting can immediately restitute coronary blood flow in an epicardial vessel, thus reperfusing ischemic tissue and salvaging the myocardium from transmural necrosis. This direct surgical technique seems to be of particular relevance in off-pump coronary artery bypass grafting, where extracorporeal circulation and global cardiac ischemia are eliminated. The anastomosis can be completed with the aortocoronary shunt in place, thus eliminating any further period of local or global ischemia.
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References
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- Lee DC, Oz MC, Weinberg AD, Ting W. Appropriate timing of surgical intervention after transmural acute myocardial infarction J Thorac Cardiovasc Surg 2003;125:115-119.[Abstract/Free Full Text]
- Reimer KA, Lowe JE, Rasmussen MM, Jennings RB. The wavefront phenomenon of ischemic cell death. 1. Myocardial infarct size vs. duration of coronary occlusion in dogs Circulation 1970;56:786-794.
- Kastrati A, Mehilli J, Nekolla S, et al. STOPAMI-3 Study Investigators A randomized trial comparing myocardial salvage achieved by coronary stenting versus balloon angioplasty in patients with acute myocardial infarction considered ineligible for reperfusion therapy J Am Coll Cardiol 2004;43:734-741.[Abstract/Free Full Text]
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Abstract
Introduction
