Ann Thorac Surg 2005;80:1904-1907
© 2005 The Society of Thoracic Surgeons
Case report
Respiratory Dependent Compression of a Venous Bypass: Therapy by Stenting
Markus J. Wilhelm, MD
a
,
c
,
*
,
Martin Igual, MD
b
,
Raymond Mury, MD
b
,
Reza Tavakoli, MD
a
,
Raoul Pescia, MD
c
,
Bruno Vettiger, MD
b
,
David Koller, MD
b
,
Marko I. Turina, MD
a
,
d
,
Michele Genoni, MD
a
a Department of Cardiovascular Surgery, City Hospital Triemli, Zurich, Switzerland
b Department of Cardiology, City Hospital Triemli, Zurich, Switzerland
c Department of Nuclear Medicine, City Hospital Triemli, Zurich, Switzerland
d Department of Cardiovascular Surgery, University Hospital, Zurich, Switzerland
Accepted for publication June 7, 2004.
* Address correspondence to Dr Wilhelm, Department of Cardiovascular Surgery, University Hospital Zurich, Raemistr 100, Zurich CH 8091, Switzerland (Email: markus.wilhelm{at}swissonline.ch).
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Abstract
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Although coronary artery bypass surgery has provided major advances in the treatment of coronary artery disease, narrowing of bypass vessels still constitutes a drawback of this therapy. Although this event is most frequently caused by intraluminal processes, obstruction from external structures is extremely rare. We report such a case in which external bypass compression was provoked by deep inspiration causing typical anginal symptoms. Percutaneous coronary intervention including stent placement provided bypass patency independent from the patient's respiratory phase. Disappearance of symptoms and absence of myocardial ischemia in perfusion scans confirmed successful treatment.
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Introduction
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In coronary artery bypass grafting, stenosis or occlusion of coronary artery bypasses with all its clinical sequelae remains a dilemma that has not been solved yet. Bypass narrowing mainly results from proliferating processes inside the graft vessel [1]. Very rarely, it is caused by external compression. Only few cases are described [2–4]. We report a case of external bypass compression only effective during deep inspiration. Patency of the affected bypass segment, independent from the respiratory state was achieved by percutaneous coronary intervention with stent placement.
Two years before the present admission, a 52-year-old white male underwent on-pump coronary artery bypass grafting. The left internal mammary artery was grafted to the left anterior descending artery, and a saphenous vein bypass was sequentially anastomosed to a diagonal and intermediate branch. Because of the hemodynamic instability after weaning from extracorporeal circulation, a vein graft was implanted in the left anterior descending artery distal to the left internal mammary artery anastomosis to warrant sufficient flow to the anterior wall. Its proximal end was anastomosed to the bypass supplying the diagonal and intermediate branch. Another venous bypass was grafted to the right coronary artery, which was not done initially because its marginal stenosis did not appear to require revascularization. Despite subsequent hemodynamic stabilization, sternum adaptation was not well tolerated. The sternum was left open with the skin approximated and was finally closed 2 days later. After prolonged weaning from the respirator, the patient was transferred to the general ward 7 days after surgery and discharged 6 days later. Ejection fraction improved from 35% preoperatively to 50% at discharge. In the 2 years postoperatively, the patient was admitted twice to another hospital for recurrent angina. The cause of the symptoms could not be identified. The patient was then referred to our hospital because of persistent exercise-induced chest pain. Ergometry provoked anginal symptoms and significant ST-segment depression in the anterior leads. Electrocardiography-triggered semiquantitative myocardial single photon emission computed tomography (gated perfusion SPECT) revealed stress-induced anterior ischemia (Fig 1). Coronary angiography showed chronic occlusion of the left internal mammary artery bypass and the bypass to the diagonal branch. The remaining bypasses, in particular the venous graft to the left anterior descending artery were open. However, it revealed a subtotal dynamic stenosis of the vein graft supplying the distal left anterior descending artery, which became evident particularly in deep inspiration (Fig 2). Holding the breath at maximal inspiration provoked the same chest pain that the patient experienced before. Stenosis was treated successfully by percutaneous transluminal coronary angioplasty and placement of a 3.5 x 18 mm sirolimus-eluting CYPHER-stent (Cordis Corp, Miami Lakes, FL) (Fig 2). Immediately after stent placement, the same respiratory maneuver failed to provoke the chest pain at maximal inspiration. These findings, together with absent laboratory signs of infection and a normal clinical examination, clearly distinguished symptoms from pleuritis. Four days after percutaneous coronary intervention, exercise electrocardiography was normal without evidence of angina or ST-segment changes, and gated perfusion single photon emission computed tomography (SPECT) showed recovery of anterior ischemia (Fig 1). The patient was discharged home free of symptoms.
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Fig 1. Electrocardiography-triggered semiquantitative myocardial single photon emission computed tomography (gated perfusion SPECT) using 99mTechnetium. Above: Short-axis view. Below: Vertical long-axis view before (left) and after (right) bypass stenting. Arrows indicate large anterior defect under stress conditions that disappeared after stenting. (SPECT = single photon emission computed tomography.)
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Fig 2. Coronary angiographic lateral view. Before stenting (left and middle): dynamic stenosis (arrow) of venous bypass to left anterior descending artery in expiration (left) and deep inspiration (middle) indicating respiratory-dependent bypass obstruction. After stenting (right): maximal inspiration failed to provoke bypass stenosis.
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Comment
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Compromise of bypass flow after coronary artery bypass grafting markedly affects patient morbidity and mortality. In particular, vein grafts are at risk for partial or total occlusion [5]. In the early postoperative period, vein graft attrition mainly resulted from thrombosis, whereas later arteriosclerosis constitutes the dominant process [1]. Variables including young age, low ejection fraction, small coronary artery diameter, large conduit diameter, the coronary artery grafted, and the time interval since operation were identified as factors affecting vein graft patency [5]. Anginal symptoms together with noninvasive evidence cause the cardiologist to perform coronary angiography, which usually reveals the diagnosis easily. In very rare cases, diagnosis may not be so clear, particularly if the cause for bypass narrowing is not an intraluminal process but compression from external structures. Thus, external compression of a saphenous vein graft 5 years after coronary artery bypass grafting was reported, which could only be identified on angiographic images in diastole. It was explained by the distended heart exerting extrinsic pressure on the graft in the diastolic phase [2]. In another case, early postoperative compression of a saphenous venous bypass by a large pericardial hematoma was reported [3]. Because the hematoma also caused compression of the right atrium and superior vena cava, the clinical picture was complicated by a combination of both ischemic left ventricular dysfunction and cardiac tamponade. Final diagnosis of graft compression was made only by surgical re-exploration. Furthermore, compression by a chest drain of a left internal mammary artery graft to the left anterior descending artery was found to be an unexpected cause of external bypass obstruction [4]. In the case presented here, diagnosis was guided by a large stress-induced anterior ischemia in SPECT imaging. Angiography revealed its cause by demonstrating phasic narrowing of the bypass graft depending on the patient's respiratory state. Local adhesions in the chest that may have formed more intensively due to the complicated perioperative course were considered to be the most likely cause of respiratory-dependent external graft compression. Percutaneous coronary intervention has been established as the treatment of choice for obstruction of coronary artery bypass grafts, although it has been found to be associated with major adverse cardiac events that may be however less frequent and severe than in redo- coronary artery bypass grafting [6, 7]. Usually percutaneous coronary intervention is performed for intraluminal obstruction of bypass grafts due to the atherosclerotic process. We believe that the patient reported herein is the first case of successful percutaneous coronary intervention with stent placement for external bypass compression.
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References
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- Shah PJ, Gordon I, Fuller J, et al. Factors affecting saphenous vein graft patencyclinical and angiographic study in 1402 symptomatic patients operated on between 1977 and 1999. J Thorac Cardiovasc Surg 2003;126:1972-1977.[Abstract/Free Full Text]
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Abstract
Introduction
