Ann Thorac Surg 2006;82:1108-1110
© 2006 The Society of Thoracic Surgeons
Case report
Intraoperative Doppler Velocity Measurements to Locate Patent ITA Grafts at Reoperation
Attilio A. Lotto, MD, MRCSI,
W. Andrew Owens, MD, FRCS(C-Th)*
Department of Cardiothoracic Surgery, James Cook University Hospital, Middlesbrough, United Kingdom
Accepted for publication January 5, 2006.
* Address correspondence to Dr Owens, Department of Cardiothoracic Surgery, James Cook University Hospital, Marton Rd, Middlesbrough, TS4 3BW United Kingdom (Email: andrew.owens{at}stees.nhs.uk).
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Abstract
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We are reporting a case of a patient who underwent an aortic valve replacement with previous coronary artery bypass grafting. During the operation we used a Doppler velocity probe to locate the exact position of the bilateral internal thoracic arteries. Once the vessels were identified, a suture was passed widely around each internal thoracic artery and a snare was positioned. With the aid of the Doppler velocity probe, we achieved a gentle occlusion of the vessels, applying enough traction on the snares to abolish the flow through the internal thoracic arteries.
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Introduction
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Redo cardiac operations, when compared with first time operations, have an increased risk of injury to the heart, great vessels, and coronary bypass grafts, when present [1]. Furthermore, in the setting of reintervention with patent coronary grafts, additional attention is required not to damage the bypass grafts when dissecting the mediastinal structures; such events considerably increase the morbidity and mortality of the operation [2, 3]. Occasionally when it is not possible to locate or isolate the bypass grafts, alternative methods of myocardial protection, such as deep hypothermia or continuous retrograde coronary perfusion need to be used [4, 5].
Methods of intraoperative detection of graft flow, such as transit time flow measurements and Doppler velocity measurements, have been extensively investigated and used during coronary artery bypass grafting [6]. In particular, Doppler velocity measurements have been advocated as a useful tool to locate intramyocardial vessels during coronary artery bypass grafting [7, 8].
We report a case of a patient in whom identification and temporary occlusion of patent bilateral internal thoracic artery (ITA) grafts was successfully achieved with the aid of Doppler velocity probe during aortic valve replacement with previous coronary artery bypass grafting.
A 58-year-old man was referred to our institution for aortic valve replacement due to symptomatic severe aortic valve stenosis (valve area, 0.4 cm2). In 1992, he had undergone double coronary artery bypass grafting with the left ITA anastomosed to the left anterior descending coronary artery and the right ITA to the distal right coronary artery.
Coronary angiography performed prior to the valve operation demonstrated that both ITA grafts were patent, with no further progression of the coronary artery disease (Figs 1A, B).
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Fig 1. (A) Coronary angiogram showing a patent left internal thoracic artery (ITA) to the left anterior descending coronary artery. (B) Coronary angiogram showing a patent right ITA to the right coronary artery.
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During the operation, after an uncomplicated redo median sternotomy and initial mediastinal dissection, we used a Doppler velocity probe (VeriQ system [MediStim, Oslo, Norway]) to exactly locate the ITAs (Fig 2). Once the vessels were located, intimate dissection of ITAs was thus avoided, with further dissection limited to those structures needed to perform the aortic valve replacement (right atrium, aortic root, pulmonary artery, and ascending aorta). Before aortic cross-clamping, two 3-0 polypropylene sutures were passed widely around the tissues surrounding both the ITAs. Occlusion of the vessels was achieved with a gentle snare, which was tightened gently (with the aid of the Doppler velocity probe positioned distally to the occlusive snare) until flow through the grafts was arrested. Cardiac arrest was achieved with antegrade and retrograde infusion of cold blood cardioplegia.
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Fig 2. Doppler measurements (A) for the left internal thoracic artery (ITA) to the left anterior descending coronary artery (LAD), and (B) for the right ITA to the right coronary artery (RCA). (DP = Doppler in cm/sec; ECG = electrocardiogram; HR = heart rate; RIMA = right internal mammary artery.)
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On completion of the aortic valve replacement, before de-clamping the aorta, the snares were released and Doppler velocity measurements were performed to ensure restoration of flow in both ITAs. The heart re-started in sinus rhythm on release of the cross clamp; however, because of sinus bradycardia, temporary external pacing was necessary to withdraw cardiopulmonary bypass and also for the first 24 hours. The patient had an uneventful postoperative recovery, and was discharged home after 7 days.
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Comment
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We believe that this is the first report of a Doppler probe used to locate patent coronary grafts during reoperative cardiac surgery, although Doppler flow detectors have been used to identify intramyocardial vessels during coronary bypass surgery [7, 8].
During redo procedures, dissection of the mediastinal structures to identify and occlude patent coronary grafts can result in graft injury, typically necessitating revision of the bypass grafts, which is particularly disadvantageous if arterial grafts have been disrupted. When visual identification and isolation of the grafts is not possible due to adhesions, strategies of myocardial protection include the use of deep hypothermia [4], antegrade or retrograde coronary perfusion, or both, with partial myocardial perfusion, and ultimately to perform the operation on a beating heart [5, 9].
We have used a novel technique that helped us locate the patent vessels without requiring extensive dissection of the mediastinal structures. The coronary angiogram showed the course of the ITAs, directing us in the initial intrathoracic dissection, but the Doppler probe identified each vessel, showing the typical curve of diastolic coronary flow (Fig 2). Once the ITAs were located, we decided not to further dissect the vessels, but to gently occlude the flow with a snare looped around the vessels and the surrounding tissues. This maneuver was aided by positioning the Doppler probe distal to the occlusion site, confirming the abolition of flow through the graft, but also avoiding injury to the ITAs by oversnaring. Just before de-clamping the aorta, the snares were released and the patency of the grafts was reassessed with the Doppler probe.
The use of the Doppler probe in this case helped us throughout the entire operation, by locating the vessels, and achieving a gentle occlusion of the vessels, enough to abolish the flow through the ITAs.
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References
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- Edwards FH, Clark RE, Schwartz M. Coronary artery bypass graftingthe Society of Thoracic Surgeons National Database experience. Ann Thorac Surg 1994;57:12.[Abstract]
- Gillinov M, Casselman FP, Lytle BW, et al. Injury to patent left internal thoracic artery graft at coronary reoperation Ann Thorac Surg 1999;67:382-386.[Abstract/Free Full Text]
- Lytle BW, McElroy D, McCarthy PM, et al. Influence of arterial arterial coronary bypass grafts on the mortality in coronary reoperations J Thorac Cardiovasc Surg 1994;107:675-683.[Abstract/Free Full Text]
- Bryne JG, Karavas AN, Filsoufi F, et al. Aortic valve surgery after previous coronary artery bypass grafting with functioning internal mammary artery grafts Ann Thorac Surg 2002;73(3):779-784.[Abstract/Free Full Text]
- Gersak B. A technique of aortic valve replacement on the beating heart with continuous retrograde coronary sinus perfusion with warm oxygenated blood Ann Thorac Surg 2003;76(4):1312-1314.[Abstract/Free Full Text]
- D'Ancona G, Karamanoukian H, Ricci M, et al. Graft patency verification in coronary artery bypass graftingprinciples and clinical applications of transit time flow measurements. Angiology 2000;31(9):725-731.
- Oda K, Hirose K, Fukutomi T, Yamashiro T, Ogoshi S. Intraoperative detection of embedded coronary arteries in MIDCAB using a color Doppler microprobe Ann Thorac Surg 1999;68:263-264.[Abstract/Free Full Text]
- Miwa S, Nishina T, Ueyama K, et al. Visualization of intramuscular left anterior descending coronary arteries during off-pump bypass surgery Ann Thorac Surg 2004;77:344-346.[Abstract/Free Full Text]
- Matsumoto Y, Watanabe G, Endo M, et al. Efficacy and safety of on-pump beating heart surgery for valvular disease Ann Thorac Surg 2002;74(3):678-683.[Abstract/Free Full Text]
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A. Elami
Patent Internal Thoracic Grafts and Reoperations
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A. A. Lotto and W. A. Owens
Reply
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Abstract
Introduction
