Ann Thorac Surg 2005;79:1769-1771
© 2005 The Society of Thoracic Surgeons
Case report
Avoidable Errors in Cardiac Surgery: Anastomosis of the Left Internal Mammary Artery to a Vein
Deepak Banerjee, MDa,
Daniel Fusco, MDb,
Jeffrey Green, MDc,
George Eapen, MDa,
Vigneshwar Kasirajan, MDb,*
a Division of Cardiology, Medical College of Virginia/VCU, Richmond, Virginia, USA
b Division of Cardiothoracic Surgery, Medical College of Virginia/VCU, Richmond, Virginia, USA
c Division of Cardiothoracic Anesthesia, Medical College of Virginia/VCU, Richmond, Virginia, USA
Accepted for publication October 30, 2003.
* Address reprint requests to Dr Kasirajan, VCU Health System, Cardiothoracic Surgery, MCV Campus, West Hospital, 7 Floor South Wing, PO Box 980068, Richmond, VA 23298-0068, USA
vkasiraj{at}vcu.edu
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Abstract
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We report the case of a patient who had undergone a three-vessel coronary artery bypass graft surgery 6 years earlier, during which the left internal mammary artery was erroneously anastomosed to an epicardial vein instead of the intended target, an intramyocardial left anterior descending artery. Visually distinguishing artery from vein can be occasionally challenging and can lead to errors in distal anastomosis. This case report identifies two difficult problems in cardiac surgery and discusses the techniques to differentiate between arterial and venous targets.
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Introduction
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Epicardial coronary arteries are identified by location and palpation during surgical myocardial revascularzation. Anomalous location such as intramyocardial course and mistaking adjacent coronary veins as arteries may lead to bypasses to veins with adverse consequences. Thus, techniques to identify arteries beyond traditional palpation and by location are important and are described in this report.
A 65-year-old woman with a medical history significant for hypertension, diabetes mellitus, and coronary artery disease underwent three-vessel coronary artery bypass surgery (CABG) in 1996 using the left internal mammary artery (LIMA) to anastomose what was thought to be the left anterior descending artery (LAD). Greater saphenous vein grafts were used to bypass the right coronary artery (RCA) and the first obtuse marginal branch of the left circumflex artery (LCX). The case was uneventful, her postoperative course routine, and she remained symptom free for 6 years. She subsequently presented in April 2002 with exertional angina and dyspnea of several weeks' duration. She was admitted to the hospital and a myocardial infarction was ruled out. She underwent cardiac catheterization, which revealed a 75% stenosis of the left main coronary artery and 100% proximal occlusion of the RCA. The LAD midsegment and distal LCX had 80% stenoses. The previous vein graft to the RCA was 90% stenosed proximally while the vein graft to the obtuse marginal had a 70% ostial lesion. Arteriography also revealed the LIMA grafted to a coronary vein, which emptied into the coronary sinus (Fig 1).
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Fig 1. Coronary angiography showing the left internal mammary artery (LIMA) anastomosed to a coronary vein draining into the coronary sinus (CS).
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The patient was taken to the operating room for a redo CABG. An intraoperative transesophageal echocargiogram showed dilated right-sided cardiac chambers, an enlarged coronary sinus with pulsatile blood flow, the PO2 of which was 125 mm Hg. During surgery, the epicardial vessels were dissected, and the LIMA was identified and divided distally at the point of vein anastomosis. The LAD was easily visualized at the apex of the heart and was traced backward until it was found to become intramyocardial in line with and just at the point where the LIMA had been previously attached. A new site for LIMA anastomosis was identified on the LAD, and an arteriotomy created. A 1-mm probe was passed retrograde up the LAD, and a stenotic lesion was encountered. Antegrade cardioplegia administered during the procedure resulted in bright red blood from the LAD. Retrograde cardioplegia, on the other hand, resulted in bright blood from the vein and deoxygenated blood from the LAD. The anastomosis was completed, and the vein ligated. The LIMA was unclamped, and the heart started activity almost immediately. The LIMA was then temporarily reoccluded, and the case completed.
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Comment
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This case presents two problems in cardiac surgery that can lead to errors in distal anastomosis, namely, intramyocardial course of the target vessel and occasional difficulty distinguishing between artery and vein. The artery is usually thick walled and diseased, but veins can sometimes too be thick and sclerosed [1]. In addition, intramyocardial arteries can often be thin walled. Under these circumstances, several techniques can aid in differentiating the two. On coronary angiography, a straight course and a location more to the right than usual gives an early clue to the intramyocardial lie of the LAD (Fig 2) [4]. During surgery, one method is to pass a probe into the artery to assess the stenotic lesion. Often, it is necessary to identify the LAD near the apex and trace it backward or to seek out the diagonal branches laterally and trace them to the LAD. Another method is to run antegrade blood based cardioplegia to assess the color of blood flowing though the vessels in question. Bright blood flow in the target vessel during antegrade cardioplegia confirms it to be an artery. Conversely, deoxygenated blood in the target vessel during retrograde cardioplegia suggests its arterial nature, whereas bright red flow makes it likely to be a vein. In cases where the LIMA has been used, a final method to aid in the distinction is to unclamp the LIMA after anastomosis. The heart will usually begin to show immediate activity, which further confirms arterial anastomosis. Occasionally, in case of an intramyocardial LAD, the right ventricle may have to be entered to find the LAD in the septum, or the LAD may have to be located just lateral to the pulmonary artery, where it originates from the left main artery.
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Fig 2. Intramyocardial left anterior descending artery. Note its sudden straight course as it enters the myocardium.
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The case discussed also represents an anecdotal report of how a patient with revascularization of the myocardium by a LIMA anastomosed to a coronary vein remained apparently symptom free for about 6 years. Since first suggested by Pratt in 1898, retrograde perfusion of the heart through the coronary sinus, coronary veins, and the Thebesius veins has been studied by numerous investigators (including Roberts and colleagues, who published results in 1943, and Beck and associates in 1948). The Beck 2 procedure created a systemic artery to coronary sinus anastomosis with a second-stage partial occlusion of the coronary sinus distally toward the right atrium [2]. The mortality rates of 7.5% for the first operation and 26.1% for the second were prohibitive, and the procedure was abandoned [3]. The theory was tested again in the 1950s by Bakst and associates using the Beck 2 [3] procedure. They were able to show retrograde perfusion and oxygen extraction along with intercoronary collateral flow. Unfortunately, severe fibrosis due to myocardial edema and hemorrhage secondary to elevated coronary sinus pressures obliterated the venous channels in a few weeks. Interest resurfaced again in 1970s, with similar disappointing results.
With more coronary artery bypasses done on the beating heart, detection of intramyocardial left anterior descending artery preoperatively or early in the course of surgery is important. Often the presence of a long segment of intramyocardial LAD will preclude off-pump coronary bypass surgery.
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References
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- Lawrie GM, Morris GC Jr, Winters WL. Aortocoronary saphenous vein autograft accidentally attached to a coronary vein: follow-up angiography and surgical correction of the resultant arteriovenous fistula. Ann Thorac Surg. 1976;22:87–90[Abstract]
- Zajtchuk R, Heydom WH, Millwe JG, et al. Revascularization of the heart through the coronary veins. Ann Thorac Surg. 1976;21:318–321[Abstract]
- Park SB, Magovern GJ, Liebler GA, et al. Direct selective myocardial revascularization by internal mammary artery-coronary vein anastomosis. J Thorac Cardiovasc Surg. 1975;69:63–75[Abstract]
- Ochner JL, Mills NL. Coronary artery surgery. Chapter 3, anatomy: correlated angiographic and surgical findings. Philadelphia: Lea and Febiger; 1978.
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Abstract
Introduction
