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Anesth Analg 2006;102:366-368 © 2006 International Anesthesia Research Society doi: 10.1213/01.ane.0000189190.93701.0d
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Abstract |
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 Top Abstract IntroductionCase ReportDiscussionReferences |
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A 71-yr-old male was scheduled for infrarenal abdominal aortic aneurysm repair. Although he had only minor clinical predictors for increased perioperative cardiovascular risk with >4 estimated metabolic equivalents for activities, intraoperative transesophageal echocardiography revealed an abnormal maximal-to-prestenotic blood flow velocity ratio in the left main coronary artery. Postoperatively, a severe distal left main coronary artery stenosis was confirmed with coronary angiography. Understanding the flow velocity patterns in the coronary arteries helps the anesthesiologist to detect coronary lesions with transesophageal echocardiography.
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Introduction |
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TopAbstractIntroductionCase ReportDiscussionReferences |
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Major vascular surgery patients are at increased perioperative cardiac risk (>5%) and often have associated coronary artery disease (CAD) (1,2). Data suggest that transesophageal echocardiography (TEE) has a high sensitivity (83%–100%) and specificity (67%–100%) in the diagnosis of significant coronary artery stenosis (3,4). We report a case of left main coronary artery (LMCA) stenosis detected with intraoperative TEE in a patient scheduled for abdominal aortic aneurysm repair.
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Case Report |
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TopAbstractIntroductionCase ReportDiscussionReferences |
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A 71-yr-old man, taking ß-blockading medication, presented for an infrarenal aortic aneurysm repair. According to American College of Cardiology/American Heart Association (ACC/AHA) guidelines, the patient had minor clinical predictors for increased perioperative cardiovascular risk with >4 estimated metabolic equivalents for activities (1). His preoperative electrocardiogram (ECG), transthoracic echocardiography, and exercise ECG test were normal. The patient was anesthetized with a target-controlled infusion of propofol and remifentanil (effect-site concentration of 3 µg/mL and 3 ng/mL, respectively). Neuromuscular blockade was established with rocuronium (0.6 mg/kg). TEE was performed and color Doppler (Nyquist limit of 0.5 m/s) examination of the LMCA showed aliasing in the distal LMCA. Pulsed Doppler interrogation upstream of the zone of aliasing (prestenotic area) demonstrated a peak diastolic velocity of 0.47 m/s. Velocities at the site of aliasing were significantly increased, with a peak diastolic velocity of 1.4 m/s. The maximal-to-prestenotic blood flow velocity ratio was 2.9, indicative of stenosis (Figs. 1 and 2) (4–6). The peak diastolic velocity in the right coronary artery (RCA) was 0.28 m/s. Surgery was well tolerated and the patient was tracheally extubated in intensive care. Aspirin was prescribed and ß-blockade continued.
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The patient in the current case experienced no intraoperative ischemia, but because of similar intraoperative TEE findings, a postoperative cardiology consult was obtained. Coronary angiography, ordered by the consulting cardiologist, confirmed a distal LMCA stenosis of 85% (Fig. 3). Two weeks later the patient underwent coronary artery bypass grafting (CABG) and recovered uneventfully. In a previous case, a patient scheduled for aortobifemoral graft prosthesis experienced intraoperative ST segment deviations. In that patient, an abnormal flow velocity pattern in the left coronary system was detected with TEE after anesthetic induction. Postoperative coronary angiography revealed triple vessel disease.
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Discussion |
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TopAbstractIntroductionCase ReportDiscussionReferences |
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With high-resolution multiplane transducers relevant information about the proximal coronary arteries can be obtained with TEE (3,4,7,8). The LMCA originates from the left coronary sinus of Valsalva and can be seen on a midesophageal aortic valve short axis view (30°) (4). The proximal LMCA runs in the left lateral direction. Slight rotation of the shaft and anteflection or retroflection is helpful to optimize Doppler beam alignment. The RCA starts from the right coronary sinus of Valsalva and runs in an anterior direction. Blood flow is well aligned with the Doppler beam, appearing as a homogenous blue line on the color flow map. Normal blood velocities are 36 ± 11 and 71 ± 19 cm/s in the LMCA during systole and diastole, respectively, 31 ± 11 and 67 ± 19 cm/s in the left anterior descending artery (LAD), and 25 ± 8 and 39 ± 12 cm/s in the RCA (7). By adjusting the Nyquist limit to 50 cm/s for the LMCA, LAD, and circumflex artery, and 20 cm/s for the RCA, normal laminar blood flow can be detected. Turbulence is the hallmark of disturbed flow and is indicative of significant upstream stenosis.
Alongside the "aliasing" phenomenon on the color flow map, a Doppler criterion of significant stenosis is a maximal-to-prestenotic flow velocity ratio 
2.0. In the cardiology literature the sensitivity and specificity of this technique have been demonstrated (5,6). However, the Society of Cardiovascular Anesthesiologists/American Society of Echocardiography (SCA/ASE) guidelines do not recommend the use of ultrasound to evaluate the coronary arteries (9).
We emphasize that this case is observational, and that some limitations apply. The normal and pathologic coronary flow velocity patterns are not validated under anesthesia. Sensitivity and specificity of this technique in anesthetized patients have not been studied but merit further investigation. Because no data are available for significant flow velocity changes during anesthesia, we used values validated for awake patients. Finally, only the proximal segments of the coronary tree can be visualized with TEE. Intraoperative assessment of obstructive CAD with TEE does not replace preoperative cardiovascular evaluation recommended by the ACC/AHA.
However, if the anesthesiologist detects Doppler recordings suggestive of significant stenosis, this presents a major problem. This finding should be recorded in the patient file and communicated to the cardiologist. Our patient received a coronary angiography and CABG. It is impossible to know whether the patient benefited from this intervention. The benefit coronary angiography and bypass surgery in this asymptomatic patient group with a high "a priori" probability for ischemic heart disease is not clear. However, improved patient mobility caused by peripheral vascular surgery might render these patients at risk for coronary events postoperatively.
In summary, intraoperative TEE can be used to detect obstructive CAD but requires additional investigation to confirm its validity and clinical impact.
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Footnotes |
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Accepted for publication September 7, 2005.
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References |
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TopAbstractIntroductionCase ReportDiscussionReferences |
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- Eagle K, Berger P, Calkins H, et al. ACC/AHA Guideline update for perioperative cardiovascular evaluation for noncardiac surgery. Circulation 2002;105:1257–67.
[Free Full Text] - Hertzer NR, Beven EG, Young JR, et al. Coronary artery disease in peripheral vascular patients: a classification of 1000 coronary angiograms and results of surgical managements. Ann Surg 1984;199:223–33.[Web of Science][Medline]
- Voros S, Nanda NC, Samal AK, et al. Transesophageal echocardiography in patients with ischemic stroke accurately detects significant coronary artery stenosis and often changes management. Am Heart J 2001;142:916–22.[Medline]
- Vrublevsky AV, Boshchenko AA, Karpov RS. Diagnostics of main coronary artery stenoses and occlusions: multiplane transoesophageal Doppler echocardiographic assessment. Eur J Echocardiogr 2001;2:170–7.
[Abstract/Free Full Text] - Hozumi T, Yoshida K, Akasaka T, et al. Value of acceleration flow and the pre-stenotic to stenotic coronary flow velocity ratio by transthoracic color Doppler echocardiography in noninvasive diagnosis of restenosis after percutaneous transluminal coronary angiography. J Am Coll Cardiol 200;35:164–8.
- Saraste M, Vesalainen R, Ylitalo A, et al. Transthoracic Doppler echocardiography as a noninvasive tool to assess coronary artery stenosis: a comparison with quantitative coronary angiography. J Am Soc Echocardiogr 2005;18:679–85.[Web of Science][Medline]
- Kasprzak JD, Drozdz J, Peruga JZ, et al. Definition of flow parameters in proximal nonstenotic coronary arteries using transesophageal Doppler echocardiography. Echocardiography 2000;17:141–50.[Web of Science][Medline]
- Biederman RW, Sorrell VL, Nanda NC, et al. Transesophageal echocardiographic assessment of coronary stenosis: a decade of experience. Echocardiography 2001;18:49–57.[Medline]
- Shanewise J, Cheung A, Aronson S, et al. ASE/SCA Guidelines for performing a comprehensive intraoperative multiplane transesophageal echocardiography examination: recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists Task Force for Certification in Perioperative Transesophageal Echocardiography. Anesth Analg 1999;89:870–84.
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