Ann Thorac Surg 2003;76:298-300
© 2003 The Society of Thoracic Surgeons
How to do it
Minimally ischemic off-pump coronary artery bypass grafting: active perfusion-assist with nitroglycerin-supplemented blood
Satoshi Muraki, MDa*,
Masaru Tsukamoto, MDa,
Kanshi Komatsu, MDa,
Jyunichi Sakata, MDa,
Syunsuke Ohori, MDa,
Takeo Hasegawa, CEa,
Tomio Abe, MDa
a Second Department of Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
Accepted for publication November 26, 2002.
* Address reprint requests to Dr Muraki, Second Department of Surgery, Sapporo Medical University School of Medicine, South 1, West 16, Chuo-ku, Sapporo 060-8543, Japan
e-mail: muraki{at}sapmed.ac.jp
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Abstract
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During off-pump coronary artery bypass surgery, concern remains about possible myocardial injury associated with the transient occlusion and stabilization of the target vessels. To try to minimize myocardial ischemia and achieve hemodynamic stability, we used a coronary perfusion catheter combined with the perfusion-assisted direct coronary artery bypass system, which enables active and modified coronary perfusion of the target vessel throughout the duration of multiple grafting.
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Introduction
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Temporary occlusion of a coronary artery, which is usually required to perform anastomosis in off-pump coronary artery bypass grafting (OPCAB), can cause hemodynamic instability and myocardial damage [1, 2].
To resolve this problem, Guyton and coworkers [3] introduced the concept of perfusion-assisted direct coronary artery bypass (PADCAB), a novel technique by which grafted vessels are perfused directly by a computer-controlled blood delivery system during multivessel OPCAB. This technique enables "active" perfusion of selected target vessels of the myocardium independent of systemic blood pressure, which contrasts with "passive" blood flow provided by intraluminal shunts or mechanical ventricular support systems. This technique also provides the option for infusion of supplemental additives for myocardial protection or myocardial vasodilation in complex cases.
To achieve ideal OPCAB, we have used a coronary perfusion catheter [4] combined with a PADCAB system (modified PADCAB) that enables active and modified coronary perfusion of the target vessel through both native coronary arteries during anastomosis and the grafted vessels during subsequent anastomosis.
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Technique
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Direct coronary perfusion during anastomosis and myocardial perfusion through completed grafts were performed using a simple circuit and a computer-controlled delivery system as originally described by Guyton and coworkers [3]. Standard median sternotomy and standard conduit harvesting techniques were used. In all cases, a single-lumen blood-access catheter (Blood Access UK II Catheter Kit, 8F; Japan Sharwood Inc, Tokyo, Japan) was inserted into either side of the femoral artery for an arterial blood source. Heparin sodium was given during the procedure to maintain an activated clotting time greater than 300 seconds. Using an additive circuit of the Myocardial Protection System cardioplegia and perfusion delivery system (Quest Medical Inc, Allen, TX), nitroglycerin (100 µg/L) was added to the blood perfusate in all patients.
The first graft was usually performed for the left anterior descending artery with direct perfusion of the distal myocardium. For direct coronary perfusion during anastomosis, a coronary perfusion catheter (Sumitomo Bakelite Inc, Tokyo, Japan) of 1.4, 1.7, or 2.0 mm in diameter, depending on the internal diameter of the target vessels, was used. The catheter was connected to a delivery line from the Myocardial Protection System, which was attached to a multiple perfusion set (Cardioplegia Adaptor CDS-003-P, Edwards Research Medical Inc, Midvale, UT; Fig 1).
For radial artery or saphenous vein graft after completion of the distal anastomosis, the proximal end of the graft was connected to a delivery line with a 3.0-mm vessel cannula (Medtronic Inc, Minneapolis, MI), and blood perfusate was administered until the time for proximal anastomosis (Fig 1). The perfusion was maintained with an infusion pressure of 120 mm Hg.
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Fig 1. Scheme of modified perfusion-assisted direct coronary artery bypass circuitry. (MPS = Myocardial Protection System.)
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In a series of 7 patients, one to three vessels were perfused in each patient. Perioperative transesophageal and transthoracic echocardiography and level of serum troponin-T were monitored in all cases as indices of myocardial damage.
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Results
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In the series of 7 patients, nine internal mammary artery grafts, five radial artery grafts, two right gastroepiploic artery grafts, and one reverse saphenous vein graft were used (2.3 ± 0.4 grafts per patient). Average time per anastomosis was 14.2 ± 2.4 minutes. One vessel was perfused in each of 2 patients, two vessels were perfused in each of 3 patients, and three vessels were perfused in each of 2 patients through the coronary perfusion catheter or the grafts. In three cases with radial artery grafts, a proximal anastomosis to the internal mammary artery as an internal mammary artery–radial artery composite graft was made to avoid touching the diseased ascending aorta.
Perfusion of the target coronary systems averaged 1,420.1 ± 509.3 mL for more than 74.8 ± 25.2 minutes under a constant infusion pressure of 120 mm Hg.
Nitroglycerin (100 µg/L of flow) was delivered directly into the coronary arteries as an additive in all patients. The average total dose was 142.0 ± 50.9 µg (range, 12.4 to 401.8 µg), and no remarkable effect on systemic pressure was noted.
Hemodynamic instability was notably absent in all cases, even in cases that required difficult anastomosis with a relatively long time for the anastomosis. There were no perioperative complications and no detectable myocardial damage (ie, impairment of myocardial wall motion indicated by echocardiography findings or by >0.25 ng/mL of troponin-T release compared with the preoperative level) in this series of patients.
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Comment
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As the feasibility of OPCAB has been demonstrated and it has been increasingly applied to complex and severe cases, strategies to reduce ischemic impairment and to achieve a safe procedure are needed [5, 6]. Although the PADCAB technique was originally applied to graft conduits after the completion of distal anastomosis [3], the target coronary artery can be perfused directly with the aid of an intraluminal device as was used in our procedure (modified PADCAB). Muraki and colleagues [7] have demonstrated that the impaired delivery of myocardial blood flow caused by intracoronary shunts or hypotension can be overcome by selective and active perfusion of target vessels using an arterial blood pump, which makes perfusion independent of upstream blood pressure. In this regard, modified PADCAB can be used for patients requiring prolonged periods of ischemia or ischemia in multiple target areas or for patients who are likely to experience systemic hypotension at some point during the surgical procedure.
In the present series of patients, we used a perfusion pressure of 120 mm Hg, which can be measured at the end of the PADCAB circuit. Based on our experimental data (not shown) showing that there is a pressure drop of approximately 20 to 30 mm Hg between the perfusion pressure and intracoronary pressure because of intervening perfusion devices (vessel cannula and perfusion catheter), we estimated actual perfusion pressure to be approximately 90 to 100 mm Hg. A perfusion pressure within the physiologic range should be used to prevent coronary injury.
In summary, active perfusion (modified PADCAB) into both native coronary arteries during anastomosis and the grafted vessels appears to facilitate OPCAB in complex cases, especially cases of multivessel coronary artery disease. The administration of a substrate, which is effective for myocardial resuscitation, cardioprotection, or vascular dilation, may also facilitate OPCAB in complex cases, including cases of evolving myocardial infarction.
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References
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- Lockowandt U.L., Owall A., Franco-Cereceda A. Myocardial outflow of prostacyclin in relation to metabolic stress during off-pump coronary artery bypass grafting. Ann Thorac Surg 2000;70:206-211.[Abstract/Free Full Text]
- Bonatti J., Hangler H., Hormann C., Mair J., Falkensammer J., Mair P. Myocardial damage after minimally invasive coronary artery bypass grafting on the beating heart. Ann Thorac Surg 1998;66:1093-1096.[Abstract/Free Full Text]
- Guyton R.A., Thourani V.H., Puskas J.D., et al. Perfusion-assisted direct coronary artery bypass: selective graft perfusion in off-pump cases. Ann Thorac Surg 2000;69:171-175.[Abstract/Free Full Text]
- Arai H., Yoshida T., Izumi H., Sunamori M. External shunt for off-pump coronary artery bypass grafting: distal coronary perfusion catheter. Ann Thorac Surg 2000;70:681-682.[Abstract/Free Full Text]
- Waldenberger F.R., Haisjackl M., Holinski S., Lengsfeld M., Konertz W. Centrifugal pumps as left ventricular assist for coronary revascularization on a beating heart. Artif Organs 1998;22:698-702.[Medline]
- van Aarnhem E.E.H.L., Nierich A.P., Jansen E.W. When and how to shunt the coronary circulation in off-pump coronary artery bypass grafting. Eur J Cardiothorac Surg 1999;16(Suppl 2):S2-S6.[Abstract/Free Full Text]
- Muraki S., Morris C.D., Budde J.M., et al. Preserved myocardial blood flow and oxygen supply-demand balance with active coronary perfusion during simulated off-pump coronary artery bypass grafting. J Thorac Cardiovasc Surg 2002;123:53-62.[Abstract/Free Full Text]
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Abstract
Introduction
