Asian Cardiovasc Thorac Ann 2007;15:234-237
© 2007 Asia Publishing EXchange Ltd
Endothoracic Papaverine Application for Internal Thoracic Artery Harvest
Muzaffer Bahcivan, MD,
Fersat Kolbakir, MD,
Hakan Karamustafa, MD,
H Tahsin Keceligil, MD
Department of Cardiovascular Surgery, Faculty of Medicine, Ondokuz Mayis University, Samsun, Turkey
For reprint information contact: Muzaffer Bahcivan, MD Tel: 90 362 457 6000 Fax: 90 362 457 6041 Email: mbahcivan{at}omu.edu.tr, Department of Cardiovascular Surgery, Ondokuz Mayis University, 55139 Kurupelit, Samsun, Turkey.
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ABSTRACT
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This study compared the effects of different methods of papaverine application on free blood flow and harvesting time of the internal thoracic artery for coronary bypass grafting. Patients were randomly divided into 3 groups of 25 each: group 1 had papaverine injected into the endothoracic tissue around the internal thoracic artery before dissection, group 2 had papaverine injected into the periarterial tissues of the internal thoracic artery pedicle, and group 3 had intraluminal papaverine applied retrogradely into the internal thoracic artery. Mean blood flow was 56.3 ± 21.3, 21.1 ± 13.2, and 20.9 ± 9.1 mL · min–1 in groups 1, 2, and 3, respectively, immediately after harvesting. Flow in group 1 was significantly better than that in groups 2 and 3. Immediately before anastomosis, mean flow was 89.8 ± 19.1, 97.6 ± 35.4, and 95.9 ± 19.9 mL · min–1 in groups 1, 2, and 3, respectively, with no significant difference among groups. Internal thoracic artery harvesting times were shorter in group 1 than in groups 2 and 3. Administering papaverine into the endothoracic fascia of the internal thoracic artery bed prior to dissection is a reliable method that facilitates rapid harvesting of the graft without causing trauma and consequent spasm.
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INTRODUCTION
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The internal thoracic artery (ITA) is commonly used for coronary artery bypass grafting (CABG) because of its superior long-term patency.1 Spasm is a major concern with the use of arterial conduits in CABG. With ITA, various problems may occur due to vasospasm both during graft preparation and in the perioperative period.2 Several types of agents are used to prevent spasm. These agents are generally applied via topical, periarterial, or intraluminal methods that might have different effects on ITA flow rates. The means of application might also give rise to complications such as ITA damage.3,4 Vasodilators are applied after harvesting the ITA, but vasospasm may occur during harvesting and it may be difficult to detect. This might cause the ITA to become damaged and possibly extend the harvesting time. As papaverine hinders spasm by causing vasodilatation, it may be easier to visualize it when administered into the endothoracic fascia prior to ITA harvest. It has been suggested that this might reduce the risk of ITA damage and shorten the duration of harvesting.5,6 The aim of this study was to compare the effects of different methods of papaverine application on the harvesting time and free blood flow in ITA prepared for CABG.
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PATIENTS AND METHODS
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After providing informed consent, 75 patients undergoing primary CABG participated in this study between January and October 2005. The patients were randomly divided into 3 groups of 25 each: group 1 received papaverine by injection into the endothoracic tissue around the left internal thoracic artery (LITA) before dissection; group 2 had papaverine injected into the periarterial tissues of the LITA pedicle; and group 3 had intraluminal papaverine applied retrogradely into the LITA. There were no significant differences in sex and age among the groups (Table 1
).
The LITA was harvested by the same surgeon in all 3 groups. A routine sternotomy was performed, followed by harvest of the LITA with a wide (2 cm) pedicle at the level of the subclavian vein beyond the bifurcation of the vessel. After visual inspection and palpation of the LITA, group 1 received 10 mg of papaverine (in 10 mL of 0.9% saline) at room temperature, by injection into the endothoracic fascia parallel to the vessel. Care was taken to avoid vascular wall infiltration. The LITA was harvested using diathermy and hemoclips to control the side branches. After completing the preparation of the graft, heparin was given, and the vessel was divided distally. The free flow from the distal cut end of the LITA continued to bleed into an open beaker for 1 minute, and the volume per minute (flow 1) was measured under controlled hemodynamic conditions. Mean arterial pressure was maintained at 70 mm Hg during the assessment of LITA flow. In the other patients, after the first flow rate of the LITA was measured, 10 mg papaverine was given periarterially to group 2 and intraluminally to group 3. Papaverine was not re-administered to group 1. The second flow measurement (flow 2) was recorded just before anastomosis of the LITA to the left anterior descending coronary artery.
Statistical analyses were performed using SPSS version 6.1 software (SPSS, Inc., Chicago, IL, USA). The chi-squared test and Kruskal-Wallis test were used for evaluation of patient characteristics. Flow 1 and flow 2 results were compared using the Kruskal-Wallis test, Mann-Whitney U test, and the Wilcoxon test. The harvesting time of the LITA was evaluated with the Wilcoxon and Mann-Whitney U tests. A p value < 0.05 was considered statistically significant.
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RESULTS
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None of the patients received sequential anastomoses with the LITA. No patient required re-exploration for bleeding. There were 2 incidents of injury to the LITA during mobilization in group 2, 7 patients had episodes of moderate hypotension, and 2 suffered intimal dissection due to intraluminal injection of papaverine. One dissection occurred at the distal end of the LITA, which could be utilized as a free graft. The other dissection involved the entire length of the vessel and it could not be used for grafting; saphenous vein was used in this patient. Four patients died due to low cardiac output, constituting an overall hospital mortality rate of 5.33%. All others were discharged from the hospital.
Mean LITA flow rates were 21.1 ± 13.2 and 20.9 ± 9.1 mL · min–1 in groups 2 and 3, respectively, before the application of papaverine, and 56.3 ± 21.3 mL · min–1 in group 1 after the application of papaverine via the endothoracic fascia (flow 1). Flow 1 in group 1 was significantly higher than that of group 2 or 3 ( p < 0.001). Mean flows before anastomoses (flow 2) were 89.8 ± 19.1, 97.6 ± 35.4, and 95.9 ± 19.9 mL · min–1 in groups 1, 2, and 3, respectively, and no significant difference was detected among the groups ( p > 0.05). Left internal thoracic artery harvesting times were shorter in group 1 than in groups 2 and 3 ( p < 0.001; Figure 1).
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DISCUSSION
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The ITA graft has the best long-term patency rate of all conduits currently used for myocardial revascularization. Its superiority is due to its high resistance to atherosclerosis.7,8 Arterial grafts have some disadvantages including spasm that arise during harvesting. The most important cause of ITA spasm is thromboxane secretion due to injury during preparation of the graft.9 Of the many agents used to treat ITA spasm, papaverine is the most commonly used in many centers and also in our clinic.10–15 The vasodilator activity of papaverine is well known. Vasodilators may be applied to the ITA in various ways including topical, by pedicular injection, or by intraluminal injection.3,6,13,16 The optimum delivery method has not been established, and studies on different means of application have shown different results.9,16–19 All of these methods for resolving spasm and increasing flow have been applied after harvesting. As the ITA is susceptible to spasm during harvesting, it may become difficult to visualize, resulting in the laceration, total or partial division, or dissection of the vessel.
Intraluminal administration of papaverine predisposes the vessel to injury. Dregelid and colleagues3 sectioned and histologically analyzed discarded ITA segments after intraluminal delivery of papaverine, and found that 8 of 52 vessels (15%) had intimal or medial disruption. This occurred in the absence of hydrostatic dilatation of the artery. Despite intimal injury, they could not identify which vessels were injured by measuring the blood flow intraoperatively. Papaverine solution is acidic with a pH of 4.2.15 Intraluminal application of papaverine is not recommended because it may damage endothelial cells.4 Mechanical vessel wall injury has also been observed in ITA treated with intraluminal papaverine.3
Endothoracic application of papaverine before harvesting the LITA was introduced by Mulay and colleagues5 who reported that it allowed easy and minimally traumatic harvesting by hydrodissection. The LITA stands out from the chest wall during injection of papaverine by this technique. Dilatation of the artery and its branches by papaverine helps visualization and allows easy division. On the other hand, Girard and colleagues6 reported that endothoracic papaverine application was no better than alternative applications in increasing ITA flow, and did not reduce the harvesting time. In our study, the first flow measurement was higher in the group that received papaverine into the endothoracic space. There were no differences in the second flow measurements among the groups, even though we did not administer a second papaverine application in group 1. Application of papaverine before ITA harvest did not cause bleeding from the veins or arteries, and it facilitated the exposure by vasodilatation. The easier exposure resulted in a shorter harvesting time.
At the outset, it was uncertain whether sufficient ITA flow could be achieved in group 1 as papaverine was applied only into the endothoracic space and the application was not repeated after harvesting. However, since there were no differences among the ITA flow rates in each group just before anastomosis, it became clear that periarterial and intraluminal papaverine applications had no superiority in terms of flow. Furthermore, the lack of complications in group 1 proved the reliability of this method. Internal thoracic artery harvesting time depends on the experience of the surgeon, but in our study, the same surgeon had shorter harvesting times in group 1 patients. Thus, it was concluded that application of papaverine to the ITA via the endothoracic fascia is a reliable method that facilitates rapid harvesting of the ITA without causing trauma and consequent spasm. By this method, effective ITA flow rates can be obtained without additional papaverine after harvesting.
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ABSTRACT
INTRODUCTION
