Eur J Cardiothorac Surg 2001;20:1261-1263
© 2001 Elsevier Science NL
Intraoperative flow measurement of native coronary artery can help decision making before CABG
Parwis Massoudy,
András Szabó,
Henry J.C.M. van de Wal,
Heinz Jakob
Department of Cardiothoracic Surgery, University of Essen, Hufelandstrasse 55, 45122 Essen, Germany
Received 4 June 2001;
received in revised form 31 August 2001;
accepted 11 September 2001.
Corresponding author. Tel.: +49-201-723-3151; fax: +49-201-723-5931
e-mail: parwis.massoudy{at}uni-essen.de
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Abstract
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We report the case of a patient with three-vessel coronary artery disease whose right coronary artery had been stented at the time of the diagnostic procedure. He had recurrent angina 12 days later and was transferred for urgent coronary artery bypass grafting. No repeat coronary angiography was performed. In the operating room, the flow on the native right coronary artery was determined with an ultrasonic flow probe.
Key Words: Coronary artery bypass grafting • Intraoperative flow measurement • Angiography
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1. Introduction
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When patients who are planned for coronary artery bypass grafting (CABG) are sent home for the waiting period (which is sometimes 4–5 months long), the coronary status may have changed by the time they come for surgery, both in the case of freedom from angina and in the case of recurrent angina. This is even more probable in patients in whom a coronary artery was stented at the time of the diagnostic procedure. The acute thrombosis rate after coronary artery stenting has been reported to be 1% [1].
The surgeon's decision whether or not to bypass a stented coronary artery in a patient with or without recurrent angina is difficult. With competitive flow on the native coronary artery and the bypass, occlusion of one or the other may occur with the threatening consequence of myocardial infarction [2,3].
Intraoperative bypass flow measurement with ultrasonic or electromagnetic systems after completion of proximal anastomoses and termination of cardiopulmonary bypass (CPB) has become a routine procedure in many centers performing CABG [4].
In the present article, we demonstrate a case where transit time flow measurement of the native coronary artery helped in the decision making of whether or not to bypass a stented coronary artery in a patient with recurring angina.
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2. Case report
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A 68-year-old patient presented at a private hospital with posterior myocardial infarction (maximal creatine kinase level, 239 U/l). Coronary angiography was performed on the same day and the occluded right coronary artery (RCA) was stented, whereafter the vessel was patent and the patient was free from angina. In the presence of significant stenoses of the left anterior descending, diagonal and intermediate branch, he was planned for elective CABG and sent home after 9 days. Two days later (12 days after stent implantation), he presented with recurrent severe angina. There was no elevation of cardiac ischemic enzymes and the electrocardiogram was not different from the one at discharge 2 days earlier. The cardiology unit decided not to perform repeat coronary angiography, but sent the patient for urgent CABG. He was operated on the same day. The surgeon had no information on whether the stent in the RCA was patent or not. After opening the pericardium, the proximal part of the RCA was dissected so that a 4.0 ultrasonic flow probe (CardioMed AS®, Oslo, Norway) could be placed around the vessel (Fig. 1)
and the coronary flow was determined thereafter by transit time flow measurement. At a mean arterial pressure of 85 mmHg, a flow of 72 ml/min was measured (Fig. 2) . After cannulation of the ascending aorta and the right atrium, CPB was instituted and the left ventricle was decompressed by a vent in the ascending aorta. Thereafter, the ascending aorta was clamped and crystalloid Bretschneider solution (Custodiol®, Köhler Chemie, Alsbach-Hähnlein, Germany) was applied for cardioplegia. The non-pulsatile flow of the RCA during instillation of Bretschneider cardioplegia was 92 ml/min. The perfusion pressure, achieved by elevation of the cardioplegic infusion bottle, was about 100 mmHg. The decision was made not to bypass the stented RCA. A sequential venous bypass was anastomosed with a marginal and intermediate branch, and the left internal mammary artery was anastomosed with the LAD. Doppler flow recording revealed a flow of 54 ml/min on the LAD graft and 49 ml/min on the sequential graft, both at a mean arterial pressure of 80 mmHg. The patient's postoperative course was uneventful and he was transferred to the Cardiology Department of the private hospital on the 4th postoperative day.
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Fig. 2. Flow in the RCA before CPB. The red line indicates mean flow value. The curve shows a strong systolic signal followed by a distinct diastolic pattern.
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3. Comment
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There is often uncertainty whether the coronary status of patients has changed when there is a considerable waiting period between diagnosis and surgery. This is especially evident when a stent has been placed at the time of the diagnostic procedure. The patient presented here had recurrent angina, but no change of his electrocardiogram and no elevation of cardiac enzymes. Therefore, the transferring cardiology unit decided not to perform repeat coronary angiography.
Competitive flow can lead to occlusion of the native vessel or the bypass and subsequent myocardial infarction. In the present case, coronary flow on the native RCA was 72 ml/min at a mean arterial pressure of 85 mmHg. Literature information about normal flow values in the RCA is sparse. It is generally supposed to be 50–80 ml/min. As expected, the flow rate during instillation of crystalloid Bretschneider cardioplegia was higher than the flow determined during cardiac work, which can be explained with a lower viscosity of the infusion fluid, with a higher mean arterial pressure and with lower outflow resistance.
There is no satisfactory correlation between bypass flow rate and patency of the graft or clinical outcome of the patient [5]. However, intraoperative flow measurement has become a widely distributed technique of flow validation for cardiac surgeons, and may well be responsible for revisions of grafts when the flow is not adequate [6].
The following arguments must be understood as limitations of the technique and the study: (1), only the RCA is suitable for this technique because of anatomic differences of the left coronary artery; (2), many cardiologists would have chosen to perform a repeat angiography in a patient with recurrent angina 12 days after stent placement; (3), a hybrid operating room with the possibility of intraoperative coronary angiography would certainly have been a very elegant solution to the problem.
The technique of intraoperative flow measurement of the native RCA with an ultrasonic flow probe may serve as a diagnostic adjunct in rare cases where the surgeon needs to have information about the patency of this vessel, e.g. after intervention by the cardiologist.
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References
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Scheller B., Hennen B., Pohl A., Schieffer H., Markwirth T. Acute and subacute stent occlusion: risk-reduction by ionic contrast media. Eur Heart J 2001;22:385-391.[Abstract/Free Full Text]
-
Salerno T.A., Mulder D.S., Chiu R.C. Intraoperative blood-flow responses in coronary artery bypass grafts. Can J Surg 1979;22:260-263.[Medline]
-
Maeta H., Imawaki S., Shiraishi Y., Arioka I., Tsuruno Y., Nagamachi E., Tanaka S. Patch angioplasty for isolated ostial stenosis of left coronary artery. Kyobu Geka 1993;46:507-511.[Medline]
-
Canver C.C., Cooler S.D., Murray E.L., Nichols R.D., Heisey D.M. Clinical importance of measuring coronary graft flows in the revascularized heart. Ultrasonic or electromagnetic?. J Cardiovasc Surg (Torino) 1997;38:211-215.[Medline]
-
D'Ancona G., Karamanoukian H.L., Salerno T.A., Schmid S., Bergsland J. Flow measurement in coronary surgery. Heart Surg Forum 1999;2:121-124.[Medline]
-
Walpoth B.H., Mueller M.F., Genyk I., Aeschbacher B., Kipfer B., Althaus U., Carrel T.P. Evaluation of coronary bypass flow with colour-Doppler and magnetic resonance imaging techniques: comparison with intraoperative flow measurements. Eur J Cardiothorac Surg 1999;15:795-802.[Abstract/Free Full Text]
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Abstract
1. Introduction
