Ann Thorac Surg 1997;64:533-535
© 1997 The Society of Thoracic Surgeons
Case Reports
Coronary Artery Problems During Homograft Aortic Valve Replacement: Role of Transesophageal Echocardiography
Tat W. Koh, MRCP,
Francis D. Ferdinand, MD,
Xu Y. Jin, MD,
Derek G. Gibson, FRCP,
John R. Pepper, FRCS
Academic Department of Cardiothoracic Surgery, Royal Brompton Hospital, London, United Kingdom
Accepted for publication March 13, 1997.
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Abstract
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We describe 2 cases in which intraoperative transesophageal echocardiography detected complications related to the proximal coronary arteries during homograft aortic valve and root replacement. In both cases, cardiopulmonary bypass could not be discontinued despite the use of large doses of inotropic drugs. Transesophageal echocardiography demonstrated aliasing on color flow mapping in the left main coronary artery in 1 case and proximal right coronary artery in the other, along with severely depressed left ventricular anterior wall and right ventricular function, respectively. Coronary artery bypass grafting was performed in both cases, and the outcome was successful.
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Introduction
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Complications related to coronary artery transfer or coronary ostial stenosis remain an important residual cause of early mortality during homograft aortic valve and root replacement [1]. We report 2 cases in which intraoperative transesophageal echocardiography was crucial in recognizing problems related to the coronary arteries during homograft aortic valve and root replacement.
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Case Reports
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Patient 1
A 59-year-old man underwent redo aortic valve replacement for bacterial endocarditis. A cryopreserved homograft aortic root was inserted, with reimplantation of the coronary arteries. When bypass was discontinued, large doses of inotropic drugs were required and it was noted that the right ventricle was enlarged and contracted poorly. Transesophageal echocardiography revealed a normally functioning aortic homograft, good left ventricular systolic function, but severely impaired right ventricular function, the free wall being almost akinetic. The right coronary artery appeared to be narrowed proximally, and aliasing on color flow mapping (Fig 1
) was seen in this region, although no ST segment changes were seen on the monitoring electrocardiogram. Bypass was therefore reinstituted and the right coronary artery grafted with reversed saphenous vein. This resulted in marked improvement in right ventricular function and the patient came off bypass easily and made an uneventful recovery.
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Fig 1. . Transesophageal echocardiogram of the aortic root and the right coronary artery demonstrating aliasing on color flow mapping, shown as the mosaic yellow and red color in the narrowed proximal segment (arrow) representing high-velocity flow, as distinct from the blue color representing laminar flow more distally. Note that only the normal laminar flow pattern is seen in the right coronary artery of patient 2 (Fig 2 ).
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Patient 2
A 70-year-old woman underwent redo aortic valve replacement for stenosis affecting her single-disc prosthesis inserted 13 years earlier. The preoperative coronary arteriogram was normal. At operation, the ostium of the left coronary artery appeared small but patent. A homograft was inserted using a two-line suture technique. When we attempted to discontinue bypass, widespread ischemic changes were noted on the electrocardiogram. Transesophageal echocardiography revealed severely impaired left ventricular anterior wall function, and color flow mapping showed aliasing in the left main coronary artery, suggesting partial obstruction (Fig 2). We reasoned that the ostium of the left main coronary artery was more importantly narrowed than previously appreciated. Cardiopulmonary bypass was reestablished and the left anterior descending artery and first marginal branch of the circumflex were grafted. Cardiopulmonary bypass was then discontinued without difficulty.
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Fig 2. . Transesophageal view of the aortic root and coronary ostia showing aliasing on color flow mapping in the left main coronary artery (long arrow) due to a significant narrowing, and the normal laminar flow pattern in the proximal right coronary artery (short arrow).
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Comment
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Complications related to the coronary arteries are an important cause of early mortality after homograft aortic valve replacement [1]. These may arise during placement of the distal suture line, which lies close to the coronary ostia, or during reimplantation of the coronary arteries for homograft aortic root replacement [1, 2]. Knott-Craig and associates [1] reported in a series of 71 patients undergoing homograft aortic root replacement that 20% of the early mortality (2 of 10 patients) was due to perioperative myocardial infarction related to coronary artery transfer. One further patient required reoperation for left coronary ostial stenosis 6 months after homograft root replacement. In an early series of homograft aortic root replacement in young patients with left ventricular outflow tract obstruction, coronary bypass grafting was required in 3 of 26 patients for problems related to torsion or malalignment of the coronary arteries [3]. Complications affecting the coronary arteries during homograft aortic valve replacement may result from ostial damage from retraction of the aorta, narrowing or distortion of the ostia due to misplacement of distal suture line, air or particulate matter embolization, and in the case of root replacement, kinking during reimplantation of the coronary arteries [3, 4].
In our patients transesophageal echocardiography could easily identify the proximal left and right coronary arteries. Narrowing of the proximal artery could be seen clearly on two-dimensional imaging, and aliasing due to high velocities could be detected on color flow mapping within the same region. This combination of findings strongly suggests that the high velocities arise as a result of partial obstruction within these proximal segments. As in atherosclerotic coronary artery disease, the association between aliasing within the coronary artery and severe depression of wall motion in the region subtended by that vessel strongly suggests compromise of coronary blood flow [5]. Although compromise to coronary artery flow may be recognized at the time by electrocardiographic changes, as in patient 2, in whom the left main coronary artery was involved, this is not always the case.
Patient 1 is noteworthy for the absence of electrocardiographic changes and for isolated involvement of the right ventricle with preserved left ventricular function. Salerno and associates [4] recently reported acute right ventricular failure after aortic valve replacements (using mechanical prostheses and homograft aortic roots) in 9 patients due to mechanical complications affecting the right coronary artery. In their report, this complication was suspected and treated on clinical grounds. In 3 patients, damage to the right coronary ostium could be confirmed by opening of the aorta and direct inspection. However, 1 patient died when this complication was unrecognized, and the diagnosis was established only at postmortem examination. The application of transesophageal echocardiography in this series of patients might have provided information on the proximal coronary arteries without the need to open the aorta for direct inspection, although acoustic shadowing might limit its use in those cases with mechanical prostheses.
Both of our patients presented with failure to be weaned successfully from cardiopulmonary bypass, and if the underlying cause of the impaired cardiac function had not been identified and corrected expeditiously, the course was likely to have been one of progressive deterioration. Intraoperative transesophageal echocardiography provided specific information that immediately clarified the diagnosis and directly influenced the management of these 2 patients. The proximity of the coronary arteries to the esophageal window and use of higher frequency transducers together with color flow mapping and Doppler echocardiography allows imaging and interrogation of the proximal coronary arteries. This ability makes transesophageal echocardiography invaluable for intraoperative assessment during homograft aortic valve or root replacement when potential problems with coronary arteries may occur and may not be recognized by conventional means.
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Footnotes
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Address reprint requests to Mr Pepper, Academic Department of Cardiothoracic Surgery, Royal Brompton Hospital, Sydney St, London SW3 6NP, United Kingdom.
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References
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- Knott-Craig CJ, Elkins RC, Stelzer PL, et al. Homograft replacement of the aortic valve and root as a functional unit. Ann Thorac Surg 1994;57:1501–6.[Abstract]
- Kirklin JW, Barratt-Boyes BG. Aortic valve disease. In: Kirklin JW, Barratt-Boyes BG, eds. Cardiac surgery, 2nd ed. New York: Churchill-Livingstone, 1993:491–573.
- Somerville J, Ross D. Homograft replacement of aortic root with reimplantation of coronary arteries. Results after one to five years. Br Heart J 1982;47:473–82.[Abstract/Free Full Text]
- Salerno TA, Bergsland J, Calafiore AM, Cordell AR, Kon ND, Bhayana JN. Acute right ventricular failure during aortic valvular operation due to mechanical problem in the right coronary artery. Ann Thorac Surg 1996;61:706–7.[Abstract/Free Full Text]
- Yoshida K, Yoshikawa J, Hozumi T, et al. Detection of left main coronary artery stenosis by transesophageal color Doppler and two dimensional echocardiography. Circulation 1990;81:1271–6.[Abstract/Free Full Text]
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Abstract
Introduction
