Ann Thorac Surg 2004;78:1814-1817
© 2004 The Society of Thoracic Surgeons
New technology
New Intraluminal Coronary Shunt Tube for Off-Pump Coronary Artery Bypass Grafting
Fuyuhiko Yasuda, MD, PhDa,*,
Manabu Okabe, MD, PhDa,
Mitsuteru Handa, MDa,
Atsushi Takamori, MDa,
Tomoaki Suzuki, MDa,
Chiaki Kondo, MD, PhDa,
Takazumi Nakamura, MD, PhDa
a Division of Cardiovascular Surgery, Kochi Municipal Hospital, Kochi, Japan
Accepted for publication September 5, 2003.
* Address reprint requests to Dr Yasuda, Division of Cardiovascular Surgery, Kochi Municipal Hospital, 7-45 Marunouchi, Kochi, Kochi 780-0850, Japan
f-yasuda{at}bronze.ocn.ne.jp
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Abstract
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PURPOSE: In cooperation with JMS Co., Ltd. (Hiroshima, Japan), we have developed a new intraluminal coronary shunt tube to allow easier, safer, and more accurate off-pump coronary artery bypass grafting (OPCABG).
DESCRIPTION: Between September 2000 and July 2002, the new shunt tube was used in 100 consecutive patients undergoing OPCABG. Patient characteristics, experimental data, and clinical results for our new shunt tube are provided.
EVALUATION: Our new coronary shunt tube was easily implanted in nearly all (97.2%) target vessels during reconstructions. All 100 cases were performed completely during off-pump operation. Early postoperative coronary angiography was performed in all 100 cases, demonstrating excellent patency in arterial grafts (99.5%) and venous grafts (96.2%). The shunt tube displayed good flow rates under experimental conditions according to diameter, and effectively prevented ischemia during coronary arterial reconstructions in all cases. No target vessels were injured on insertion or removal of shunt tubes. Neither perioperative complications nor hospital deaths were encountered.
CONCLUSIONS: This new shunt tube improves the safety, accuracy, and ease of OPCABG surgery.
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Introduction
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With off-pump coronary artery bypass grafting (OPCABG) surgery, concerns exist regarding control of blood flow during distal anastomosis. Intraluminal coronary shunts have been introduced into clinical practice to maintain distal perfusion and allow construction of the anastomosis in a bloodless field [1, 2]. Given the need for a coronary shunt tube that is more easily inserted into target vessels and facilitates distal anastomosis, we developed a new intraluminal coronary shunt tube in cooperation with JMS Co., Ltd. (Hiroshima, Japan). We describe our experiences with OPCABG using the new coronary shunt tube and report on the associated efficacy and safety.
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Patients and Methods
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Between September 2000 and July 2002, a total of 100 consecutive OPCABG operations were performed using the new coronary shunt tube. Myocardial revascularization was performed using minimally invasive direct coronary artery bypass grafting (MIDCABG) in 28 patients and using transsternal OPCABG in 72 patients. A total of 202 arterial graft anastomoses and 52 venous graft anastomoses were performed. Our new shunt tube was inserted initially in all anastomoses, irrespective of coronary territory. Postoperative angiographies were performed within 2 weeks postoperatively in all cases. Preoperative patient characteristics are summarized in Table 1.
Mean flux for the new intraluminal coronary shunt tube was calculated by measuring the outflow blood weight with a pressure head of 1,000 mm H2O using bovine blood in order to determine flow capacity of the shunt tube. Measurements were made in five pieces of tubes for each diameter, and results were averaged for each size. Flow results were then compared with another major marketed coronary shunt tube (ClearView; Medtronic, Minneapolis, MN).
New Intraluminal Shunt Tube
The characteristics of our new intraluminal coronary shunt tube are as follows: (1) a wedge-shaped head and polyamide guidewire (Fig 1, A) facilitate insertion, as do adequate kinking and restoring properties (Fig 1, B); (2) eccentric configuration of the head allows more space for anastomosis than ordinary designs, and the retention suture knot is small enough to easily pass through the coronary arterial lumen, making insertion easy and safe (Fig 2); (3) good rates of blood flow can be obtained according to diameter (Fig 3); and (4) the tube uses the same polyamide resin as the soft tips for angiography catheters and is coated with heparin, preventing thrombosis and injury to coronary endothelial cells.
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Fig 1. (A) New intraluminal coronary shunt tube (JMS bypass tube; JMS, Hiroshima, Japan). (B) Shape during insertion, with suitable kinking and restoring properties
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Fig 3. Flow rates for intraluminal coronary shunt tube according to diameter. Flow rates were measured in bovine blood under conditions as follows: hematocrit 33%, hemoglobin 12.1 g/dL, total protein 5.2 g/dL, temperature 25°C to 27°C, pressure head 1,000 mm H2O. Mean ± SD, n = 5. *p less than 0.01. Solid bars = JMS bypass tube; open bars = ClearView shunt tube.
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Statistics
Data are expressed as mean ± SD. Comparisons between groups were performed using Student's t test when appropriate, and differences were considered statistically significant for values of p less than 0.05.
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Results
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Myocardial revascularizations were performed using MIDCABG in 28 cases, and transsternal OPCABG in 72 cases. Using our new coronary shunt tube, the application of the temporary intraluminal shunt into the target vessel was very easy. No injuries to target vessels were encountered with this shunt tube. Severe calcification of target vessels was observed in 7 cases (7.0%), but the new coronary shunt tube could be safely introduced into target vessels using the original guide in these cases. The success rate for coronary shunting with our shunt tube was 97.2% (247 of 254).
Postoperative angiography was performed on all 100 cases. The patency rate was 99.5% for arterial grafts and 96.2% for vein grafts. String signs were observed in 3 arterial grafts, including the left internal thoracic artery, radial artery, and right gastroepiploic artery grafts, all of which were due to competition. Anastomotic stenoses were found in 2 cases, both of which were on the heel side of the left internal thoracic artery grafts, and were probably due to technical failures. No new stenoses occurred in native coronary vessels (Table 2).
Neither perioperative myocardial infarctions nor hospital deaths were encountered.
Measurements of in vitro flux revealed the capacity for significantly higher flow volume in our new intraluminal coronary shunt tube compared with the ClearView shunt tube (p < 0.01).
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Comment
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To limit regional ischemic changes that occur during snaring, some surgeons now use intraluminal coronary shunts [3–5]. Issues involved in coronary shunting include difficulties in implanting shunt tubes inside target vessels during reconstruction, maintaining shunt flow volume to prevent ischemia, possible injury to target vessels, and the value of routine use of shunt devices for anastomotic constructions [5]. We therefore developed a new intraluminal coronary shunt tube to solve these issues. Our new shunt tube offers easy insertion with the wedge-shaped head, soft shaft made of polyamide resin, and attached guide. The new shunt tube was usable in all coronary anastomosis sites, irrespective of territory and quality of target vessel. Success of coronary shunting during revascularization reached 97.2% (247 of 254). Once inserted in the target vessel, the eccentric shape of the tube head allows more space for anastomosis in the coronary lumen than ordinary tubes, in addition to providing a bloodless surgical field, in turn allowing easier and more accurate suturing. That also prevents inadvertent stitching of the back wall of the coronary artery and allows release of occlusive coronary snares, which can reportedly cause target vessel damage. Using our new coronary shunt tube, excellent results were achieved for OPCABG, with patency rates of 99.5% in arterial grafts and 96.2% in venous grafts and a total patency rate of 98.8%.
Shunt tubes are reportedly effective in preventing ischemia during vascular control and suturing [6, 7]. This report provides experimental data for the blood flow volume of our new shunt. These experimental data have revealed the significantly greater capacity for blood flow volume of our new intracoronary shunt tube compared with the standard shunt tube. This shows the capabilities of the new shunt tube for preventing ischemia during coronary reconstruction. In our experience, hemodyanamic instabilities and ischemic changes on electrocardiography occur in 10% of OPCABG operations after the snaring procedure. However, all these instabilities disappeared after implantation of the coronary shunt tube, clinically proving that our coronary shunt tube can deliver sufficient blood flow to prevent ischemia during coronary revascularization.
Although OPCABG is recognized as less invasive than conventional coronary artery bypass grafting, the procedure is somewhat invasive, particularly to the coronary endothelium. Technical devices such as coronary snaring, clamping, shunting, and gas insufflation required to obtain optimal operative fields can cause lesions to the endothelium leading to coronary endothelial dysfunction, platelet aggregation, intimal dissection, and plaque rupture [8–10]. Conversely, coronary shunting itself prevents blood from obscuring the operative field, reduces the need for snares, clamping, and gas insufflation, and could possibly ameliorate coronary endothelial injury. Our new shunt tube is made of the same polyamide resin as the soft tips on angiography catheters, and is coated with heparin to prevent thrombosis and injury to coronary endothelial cells. The excellent clinical results, including good graft patency and high quality of anastomoses with no new stenoses in native vessels, suggest the safety of our shunt tube for application to the coronary artery. However, the present clinical study cannot determine the precise effects of the shunt tube on coronary endothelial structures and functions and platelet activities.
The new coronary shunt tube was easily inserted into nearly all target coronary vessels, effectively prevented ischemia, maintained a bloodless surgical field, expanded and stented the suture line, and significantly eased the task of surgeons by permitting careful, diligent, and unhurried suturing. As a result, OPCABG was performed in all of the 100 elective CABG patients under stable circulatory conditions, allowing accurate distal anastomosis and excellent results.
In conclusion, our new intraluminal coronary shunt tube represents an innovative device that facilitates OPCABG.
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Disclosures and Freedom of Investigation
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We had full control of the design of the study, methods used, outcome indicators, analysis of data, and production of this report. Measurements of in vitro flux of our shunt tube were done with the technical support of JMS Research and Development (Hiroshima, Japan) and the animal blood was provided by JMS. The company provided the shunt tube free of charge for these experiments but no funding for this study.
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Footnotes
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The Society of Thoracic Surgeons, the Southern Thoracic Surgical Association, and The Annals of Thoracic Surgery neither endorse nor discourage use of the new technology described in this article.
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References
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- Trapp WG, Bisarya R. Placement of coronary artery bypass graft without pump oxygenator. Ann Thorac Surg. 1975;19:1–9[Medline]
- Rivetti LA, Gandra SMA. Initial experience using an intraluminal shunt during revascularization of the beating heart. Ann Thorac Surg. 1997;63:1742–1747[Abstract/Free Full Text]
- Dapunt OE, Raji MR, Jeschkeit S, et al. Intracoronary shunt insertion prevents myocardial stunning in a juvenile porcine MIDCAB model absent of coronary artery disease. Eur J Cardiothorac Surg. 1999;15:173–178[Abstract/Free Full Text]
- Lucchetti V, Capasso F, Caputo M, et al. Intracoronary shunt prevents left ventricular function impairment during beating heart coronary revascularization. Eur J Cardiothorac Surg. 1999;15:255–259[Abstract/Free Full Text]
- Yeatman M, Caputo M, Narayan P, et al. Intracoronary shunts reduce transient intraoperative myocardial dysfunction during off-pump coronary operations. Ann Thorac Surg. 2002;73:1411–1417[Abstract/Free Full Text]
- Gandra SM, Rivetti LA. Experimental evidence of regional myocardial ischemia during beating heart coronary bypass: prevention with temporary intraluminal shunts. Heart Surg Forum. 2002;6:10–18[Medline]
- Rivetti LA, Grandra SM. An intraluminal shunt for off-pump coronary artery bypass grafting. Report of 501 consecutive cases and review of the technique. Heart Surg Forum. 1998;1:30–36[Medline]
- Hangler HB, Pfaller K, Antretter H, et al. Effects of intracoronary shunts on coronary endothelial coating the human beating heart. Heart Surg Forum. 2003;6(Suppl 1):46
- Perrault LP, Desjardins N, Nicker C, et al. Effect of occlusion devices for minimally invasive coronary artery bypass surgery on coronary endothelial function of atherosclerotic arteries. Heart Surg Forum. 2000;3:287–292[Medline]
- Demaria RG, Fortier S, Perrault LP, et al. Influence of intracoronary shunt size on coronary endothelial function during off-pump coronary artery bypass. Heart Surg Forum. 2003;6:160–168[Medline]
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Abstract
Introduction
