safe anesthetic care in patients with coronary artery disease. It is well known that myocardial ischemia may occur without previous electrocar- diographic (ECG) ...
Early Detection by Transesophageal Echocardiography of Severe Regional Myocardial Ischemia Due to Intracoronary Air Embolism J.P. Mulier, MD, R. Demeyere, MD, P. Sergeant, MD, PhD, and H. Van Aken, MD, PhD
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of intraoperative myofor providing safe anesthetic care in patients with coronary artery disease. It is well known that myocardial ischemia may occur without previous electrocardiographic (ECG) changes.ls4 Transesophageal echocardiography (TEE) can be used for early detection of regional wall motion changes during ischemia.5M8 Although the anterior wall of the right ventricle can be inspected directly during weaning from cardiopulmonary bypass (CPB), only with TEE can early detection of abnormal wall thickening and movements of other regions of the heart be observed. A case report is presented of early detection of severe myocardial ischemia of the inferoseptal region after coronary artery bypass grafting that was thought to be caused by an intracoronary air embolus. cardial ischemia is important
CASE REPORT A 66-year-old man (63 kg) was scheduled for his third coronary artery revascularization. He had his first operation in 1973 using a mammary artery free graft to the right coronary artery (RCA). After early occlusion of this free graft, a venous bypass was constructed to the RCA in 1974. In 1980, he underwent an aortofemoral graft for peripheral vascular disease. Cardiac ischemic symptoms returned in 1987, and calcium entry blockers and nitrates were given. Catheterization showed stenosis of the venous bypass to the RCA and a new stenotic lesion in the left anterior descending (LAD) coronary artery. The ECG showed an old inferior myocardial infarction, and preoperative echocardiography and cardiac catheterization showed inferoseptal hypokinesis. On arrival in the operating room, an ECG was attached and leads II and V, were displayed continuously. Catheters were inserted into a peripheral vein and a radial artery under local anesthesia. The patient remained in stable hemodynamic condition during induction with etomidate, 20 mg, sufentanil, 0.2 mg, and pancuronium bromide, 6 mg. He was ventilated using an air/oxygen mixture with an F,O, of 0.5. Anesthesia was maintained by intermittent sufentanil administration up to a total dose of 1.2 mg. After inserting pulmonary arterial and central venous catheters, the TEE probe (Hewlett-Packard, Andover, MA; 5.0 MHz) was introduced into the esophagus and positioned in a short-axis view. The first examination after induction showed good left ventricular function with a hypokinetic inferoseptal region. After an uneventful sternotomy, extracorporeal circulation (ECC) was initiated. Lidoflazine was used as a myocardial
protective drug, as part of a standard protocol for coronary artery bypass patients.9 The patient was cooled to a body temperature of 28OC. A left mammary artery graft was anastomosed to the LAD, and a venous bypass was constructed between the aorta and the RCA. A perfusion pressure above 80 mm Hg was maintained during the ECC. The patient was rewarmed and was ready to be weaned from ECC. At that time, the TEE showed a return to the preoperative state (Fig 1A) with mild hypokinesis in the inferoseptal region. Suddenly, dramatic changes in contraction of the posterior and the inferoseptal regions were noted by TEE (Fig 1B). Acute akinesis occurred in both regions. Bradycardia, conduction disturbances, and ST segment elevations became apparent (Fig 1C) 4 minutes later. Atrioventricular sequential pacing was then initiated. Before the surgeon could assess the patency of the grafts, the heart fibrillated (Fig 1D). After prompt defibrillation, inspection of the RCA graft, responsible for the inferoseptal region, did not show any obvious explanation. However, needle aspiration of the RCA graft showed intracoronary air. Removal of the air embolism quickly improved the contraction in the akinetic zones, and the hemodynamic performance improved. Weaning from CPB was easily performed with minimal inotropic support. The TEE returned to the preoperative contractility pattern, with hypokinesia in the septal region (Fig 1E). However, the ischemia remained for a longer time on the ECG. The postoperative course was uneventful. No ischemia was noted by the second postoperative day, and the levels of cardiac isoenzymes remained normal.
DISCUSSION
This case demonstrates the practical clinical use of the TEE during cardiac anesthesia. This new monitoring technique detects very early changes in myocardial contractility,2T5*6 and regional contractile abnormalities in dogs have been found to provide a more sensitive indicator of ischemia than electrocardiographic ST-T segment changes.3 However, ECG changes can be observed sometimes without wall motion changes.
From the Department of Anesthesiology, University Hospitals, Katholieke Universiteit. Leuven, Belgium. Address reprint requests to J.P. Mulier, MD, Department of Anesthesiology. University Hospitals. Katholieke Universiteit Leuven. Herestraat 49, B-3000 Leuven, Belgium. o 1990 by W.B. Saunders Company. OSSS-6296/90/04OS-0013%03.00/0
Journal of Cardiothoracic Anesthesia, Vol 4, No 5 (October), 1990: pp 62 l-623
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ECG and echocardiographic images: diastole at the left, systole at the right. (A) 13.15 h-patient is rewarmed and Fig 1. ready for weaning from ECC; mild hypokinesis inferoseptal: no change from preoperative echocardiogram; mild ST elevation: no change from preoperative ECG. (B) 13.20 h-acute ekinesis of the inferoseptel region; no change in ST depression. (C) 13.24 h-further deterioration of regional wall motion ST elevations with conduction disturbances.
This could be because of the fact that with the TEE only one plane is being observed, whereas the ECG is monitoring a wider area of the heart. Localizing the affected zone by TEE or ECG can direct the surgeon to the graft responsible for blood flow in that region. With the TEE it is not possible to make a clear diagnostic distinction between an infarcted
zone, a chronically ischemic zone, or an acutely ischemic zone. They can all show similar functional deficits. Only the evolution over time can make the difference clear.4 Infarcted zones have fixed deficits, whereas acute ischemic zones show deficits that change in time and place. Therefore, ideally, the TEE should be monitored before an ischemic event takes place. Otherwise the distinc-
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Fig 1. (Cont’d). (D) 13.31 h-ventricular fibrillation. region; ischemia (ST elevation) remains on the ECG.
tion between a new ischemic zone with hypokinesis, and a long-existing hypokinetic area will not be easy to make. In summary, this case shows how the TEE can detect early changes in myocardial contrac-
(E) 14.56
h-after
weaning
from ECC; hypokinesia
in the septal
tion, suggesting changes in myocardial perfusion, and how it can initiate early and directed therapy. Detection and treatment of an acute coronary air embolism is one of many possible uses for this new monitoring technique.
REFERENCES 1. Cahalan MK, Litt L, Botnivick EH, Schiller NB: Advances in noninvasive cardiovascular imaging: Implications for the anesthesiologist. Anesthesiology 66:356-372, 1987 2. Smith JS, Cahalan MK, Benefiel DJ, et al: Intraoperative detection of myocardial ischemia in high-risk patients: Electrocardiography versus two-dimensional transesophageal echocardiography. Anesthesiology 66:64-68 3. Battler A, Froelicker VF, Gallagjer KP: Dissociation between regional myocardial dysfunction and ECG changes during ischemia in the conscious dog. Circulation 62:735, 1980 4. Mann DL, Gillam LD, Weyman AE: Crosssectional echocardiographic assessment of regional left ventricular performance and myocardial perfusion. Prog Cardiovast Dis 29:1-52, 1986
5. Abel MD, Nishimura RA, Callahan MJ, Rehder K: Evaluation of intraoperative transesophageal two-dimensional echocardiography. Anesthesiology 66:64-68, 1986 6. Clements FM, de Bruijn NP: Perioperative evaluation of regional wall motion by transesophageal twodimensional echocardiography. Anesth Analg 66:249-261, 1987 7. Cobb FR, Chu A: Myocardial infarction and risk region relationships: Evaluation by direct and noninvasive methods. Prog Cardiovasc Dis 30:323-348, 1988 8. Beaupre PN, Kremer PE, Cahalan MK, et al: Intraoperative detection of changes in left ventricular segmental wall motion by transesophageal two-dimensional echocardiography. Am Heart J 107:1021-1023,1984 9. Flameng W, Daenen W, Borgers M: Cardioprotective effect of lidoflazine during one hour of normothermic global ischemia. Circulation 64:796-807, 1981
