A 65-year-old woman with progressive dyspnea and significant mitral and aortic valve stenosis underwent dual valve replacement with bileaflet mechanical prostheses. Preoperative echocardiography and coronary angiography revealed normal coronary arteries and normal left ventricular (LV) function. Two days after surgery, the patient had progressive angina pectoris, ST-segment elevation, and increased cardiac enzyme levels, suggesting an acute coronary event. Echocardiography showed normally functioning prostheses and LV systolic dysfunction (ejection fraction, 0.35). The patient's left main coronary artery (LMCA) was examined with use of dual-source 256-slice multidetector computed tomography (CT). Retrospective electrocardiographic gating with current tube modulation was used to obtain images throughout the cardiac cycle and to reconstruct them at optimal times. A LMCA dissection flap extended to the left anterior descending coronary artery (Figs. 1 and 2). The patient underwent successful coronary artery bypass grafting.
Fig. 1 Contrast-enhanced cardiac computed tomography (2-chamber view) shows a normally functioning prosthetic mitral valve (arrow) and a left main coronary artery intimal flap with extension to the proximal left anterior descending coronary artery (arrowhead).
LA = left atrium; LV = left ventricle
Fig. 2 Contrast-enhanced cardiac computed tomography (reconstructed short-axis view) shows the valve prostheses (aortic, black arrow; and mitral, white arrow) in relation to the intimal flap (arrowhead) in the left main coronary artery and the proximal segment of the left anterior descending coronary artery (arrowhead).
Comment
Iatrogenic LMCA dissection in the early postoperative period is rare after mechanical or bioprosthetic valve surgery. Ischemic symptoms in the first 6 postoperative months suggest iatrogenic coronary artery stenosis. The most likely pathophysiologic mechanisms are post-traumatic fibrous intimal proliferation and, rarely, LMCA dissection. Both are caused by direct coronary ostia cannulation for cardioplegia.1,2 Presentation in the immediate postoperative period is rare and is generally caused by thrombosis or dissection.3
In our patient, cardiac CT revealed LMCA dissection and obviated the need to repeat invasive coronary angiography early after surgery because of extensive myocardial infarction.4,5 (However, had the CT results been normal, we would have repeated angiography.) Cardiac CT enables satisfactory evaluation of prosthetic valve malfunction,6 pleural and pericardial effusion, acute aortic syndrome, and pulmonary emboli in patients who are doing poorly postoperatively. Scanning with 256-slice CT yields better image quality, wider coverage, shorter scan acquisition times, and less image artifact at higher heart rates than does scanning at 64 slices or lower.
Footnotes
Address for reprints: Anita Sadeghpour, MD, Noninvasive Cardiac Imaging Laboratory, Echocardiography Research Center, Rajaie Cardiovascular Medical and Research Center, Tehran University of Medical Science, adjacent to Mellat Park, Tehran 1996114151, Iran
E-mail: ani_echocard@yahoo.com
References
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