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ORIGINAL ARTICLE Table of Contents   
Year : 2010  |  Volume : 13  |  Issue : 3  |  Page : 231-235
Intraoperative anastomotic site detection and assessment of LIMA-to-LAD anastomosis by epicardial ultrasound in off-pump coronary artery bypass grafting - A prospective single-blinded study


Department of cardiac anesthesia and cardiac surgery, Sri Ramachandra Medical College, Porur, Chennai, India

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Date of Submission16-Dec-2009
Date of Acceptance15-Jul-2010
Date of Web Publication6-Sep-2010
 

   Abstract 

The study was done to detect the optimal site of left anterior descending (LAD) artery for grafting and for the assessment of geometrical and anatomical characteristics of left internal mammary artery (LIMA)-to-LAD artery anastomosis in elective off-pump coronary artery bypass grafting surgery. Fifteen consecutive patients who underwent coronary artery bypass graft (CABG) were included in the study. All the operations were performed by a single surgeon. Epicardial ultrasound probe was placed at the site of grafting for scanning and the site of anastomosis selected. The anticipated target site selected by the surgeon was scanned for patency, size, septal perforator branches, and presence of plaque and calcification. The surgeon identified the LAD artery in 12 patients. In three patients, the LAD artery was not visible. However, with epicardial ultrasound, the LAD artery was identified in all patients. In 6 of 15 patients, the anticipated target anastomotic site was changed to a clear segment either due to the presence of perforators or plaques or calcifications. In all 15 patients, the surgeon scored the anastomosis as good, based on his or her experience independent of the ultrasound image. The anastomotic score by the cardiac anesthesiologist showed 5 anastomoses with satisfactory results and 10 anastomoses with good results. The study demonstrates that epicardial ultrasound scanning with a 10-MHz transducer provides reliable information in choosing the proper anastomotic site and allows proper visualization of LIMA-to-LAD anastomosis. All these measurements are easily obtained without risk of any complications and the method is not time consuming.

Keywords: Anastomosis, CABG, epicardial, ultrasound

How to cite this article:
Ravulapalli HB, Karthekeyan RB, Vakumudi M, Srigiri R, Saldanha R, Sulaiman S. Intraoperative anastomotic site detection and assessment of LIMA-to-LAD anastomosis by epicardial ultrasound in off-pump coronary artery bypass grafting - A prospective single-blinded study. Ann Card Anaesth 2010;13:231-5

How to cite this URL:
Ravulapalli HB, Karthekeyan RB, Vakumudi M, Srigiri R, Saldanha R, Sulaiman S. Intraoperative anastomotic site detection and assessment of LIMA-to-LAD anastomosis by epicardial ultrasound in off-pump coronary artery bypass grafting - A prospective single-blinded study. Ann Card Anaesth [serial online] 2010 [cited 2019 Sep 19];13:231-5. Available from: http://www.annals.in/text.asp?2010/13/3/231/69069



   Introduction Top


The aim of coronary artery bypass graft (CABG) surgery is to increase the blood flow to the ischemic myocardium. Early graft failure is a potential life-threatening complication after coronary artery bypass grafting. In this respect, a good quality of anastomosis is crucial and a reliable method for the assessment of proper anastomosis would be beneficial to prevent this complication. [1] Epicardial ultrasound is a useful method for the intraoperative assessment of graft anastomosis quality but needs to demonstrate its ability to predict graft revision. [2] Finding the "optimal" target area on the left anterior descending coronary (LAD) artery to construct a patent coronary anastomosis can be rendered more difficult when it is deeply embedded in the epicardial fat or myocardium. Plaque and calcifications in the target segment make anastomosis suturing difficult. Intense bleeding from a septal perforating branch in the occluded coronary segment may impair the visibility and also loss of the perforator branch in anastomotic sutures. Perforator branches are difficult to identify because they may not be visualized well on preoperative angiograms. [3]

The present study was conducted to identify the optimal target anastomotic site of the LAD artery and for the assessment of anastomosis of left internal mammary artery (LIMA) to LAD artery by epicardial ultrasound (GE Vingmed 10-MHz ultrasound probe, Horton, Norway).


   Materials and Methods Top


Patient selection and demographics

The study protocol was approved by the institutional ethics committee and informed consent was obtained from each patient. Fifteen consecutive patients (13 males, 2 females) scheduled for elective off-pump coronary artery bypass grafting (OPCAB) were included in the study. All patients received LIMA-to-LAD graft.

Surgical technique

All operations were performed via median sternotomy by a single surgeon. After heparinization (1 mg/kg), the LIMA was harvested with its pedicle and a diluted solution of papaverine was sprayed. The activated clotting time was maintained above 270 s. Epicardial ultrasound probe was placed at the site of grafting for scanning and the site of anastomosis was selected. The harvested LIMA was then anastomosed to the selected site on the LAD.

Epicardial ultrasound scanning

After application of the epicardial stabilizer (Octopus 4.3, Medtronics, USA), epicardial scanning of the anastomotic site was performed. With a sterile gel as the conduction medium, the 10-MHz ultrasound probe transducer was placed in the sterile glove and applied on to the epicardium between the paddles of the stabilizer. The anticipated target site selected by the surgeon was scanned for patency, size, septal perforator branches, and presence of plaque and calcification [Figure 1]. The number of times the surgeon deviates from the original anticipated site for grafting based on epicardial scanning was noted.
Figure 1: Ultrasound Doppler showing LAD with plaque and septal perforator

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Anastomosis scoring procedure

The surgical anastomosis was graded good, satisfactory, or poor by the surgeon depending on his or her surgical expertise of feeling the pulsations of LIMA and the precision of anastomosis. The senior cardiac anesthesiologist who was trained in transesophageal echocardiography scored the surgical anastomosis based on ultrasound images, applying the criteria developed by Budde [Table 1]. The scoring of the surgeon and cardiac anesthesiologist was blinded from each other. The quality of image was rated good when both the anastomoses and the distal run-off in the coronary artery could be visualized by color Doppler. Images obtained from anteroposterior and transverse planes were used to assess the quality and patency of the anastomosis.
Table 1: Patients characteristics


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   Statistical Analysis Top


Data normally distributed were described as arithmetic mean and standard deviation (SD), which was the measure of variability. The chi-square test was used to compare surgeon's score with the ultrasound score measured by anesthesiologist.

Results

The mean age, height, and weight are given in [Table 2].
Table 2: Scoring criteria by Budde


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LAD identification

The surgeon identified the LAD artery in 12 patients. In three patients, the LAD artery was not visible, the reason being epicardial fat and intramural location. However, with epicardial ultrasound, the LAD artery was identified in all patients.

Coronary target vessel detection

Plaques and calcifications were detected in all cases by epicardial ultrasound. In 6 of 15 patients, the anticipated target anastomotic site was changed to a clear segment either due to the presence of perforators or plaques or calcification [Figure 2]. In all 15 patients, the septal perforator branches were identified along the run of the LAD artery [Table 3].
Table 3: Left anterior descending coronary artery (LAD) assessment


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Figure 2: Diagram showing A1-A2 ratio, A1 = anastomotic orifice, A2 = coronary artery diameter at 3 mm distal to the toe

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Anastomosis assessment

In all 15 patients, the surgeon scored the anastomosis as good, based on his or her experience independent of the ultrasound image. The anastomotic score by the cardiac anesthesiologist showed 5 anastomoses with satisfactory results and 10 anastomoses with good results [Table 4].
Table 4: Results of anastomotic scoring


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   Discussion Top


During OPCAB, the distal anastomoses are performed under suboptimal conditions and the incidence of technical abnormalities of distal anastomosis requiring revision has been reported to be as high as 9.9%, reflecting the need for an intraoperative method capable of detecting anastomotic errors. [1] Various available methods for the verification of intraoperative graft patency such as intraoperative angiography, thermal imaging, transit time flowmetry, and audible Doppler probes have not been widely used due to associated cost, difficult interpretation without anatomical information, and lack of reproducibility or inaccuracy. [4] Most surgeons use none of these technologies, possibly because of a lack of knowledge, a lack of economic resources, or a lack of interpretation guidelines. [4]

A patent LIMA-to-LAD graft is the single most important determinant of the long-term and event-free survival and imperfect graft anatomosis has a poor long-term patency after CABG. [5],[6] Epicardial color Doppler scanning allows an accurate assessment of LIMA-to-LAD anastomosis and provides three important pieces of information: (i) visualization of anastomosis and its components (LAD, LIMA), (ii) measurement of the length of anastomosis properly as well as diameters of LAD downstream and the LIMA [Figure 2], and (iii) color Doppler assessment of the blood flow velocity at the anastomotic sites. The epicardial ultrasound was effective in locating septal perforating branches and calcifications in the coronary target segments. In our study, this led to the change in the anastomotic site in six patients [Figure 3]. This, we believe, helped us to avoid postarteriotomy problems and enhance the clinical outcome.
Figure 3: Bar diagram showing the reason for changing the site of anastomosis

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Assessing anastomosis geometry and patency on epicardial ultrasound seemed to be more complex due to limited experience with the interpretation of such images. The observer believed that the criteria developed by Budde provided a good guideline for anastomosis assessment. [7] In our study there, was no need for reintervention, probably due to the fact that an ultrasound image allows a look inside the anastomosis. Specific training for assessing anastomostic scans may be necessary to build the comfort level for surgeons to trust the ultrasound image enough to redo an anastomosis.

The correct use of graft patency verification tools and interpretation of their intraoperative findings are not always immediate and have a learning curve. In this regard, we believe that these techniques should be part of a routine examination that will help surgeons and anesthesiologist familiarize themselves with the technology. Based on our results, epicardial ultrasound scanning seems to be an extremely valuable tool in the cardiac operating room during CABG surgery.

Limitations

The study has following limitations:

  1. Small sample size.
  2. Anesthesiologist's and surgeon's observer bias.
  3. Learning curve of the technique.
  4. Postoperative angiographic follow-up.



   Conclusion Top


The present study demonstrated that epicardial ultrasound scanning with a 10-MHz transducer provides reliable information in choosing the proper anastomotic site and allows proper visualization of LIMA-to-LAD anastomosis. All these measurements are easily obtained without risk of any complications and are not time consuming.

 
   References Top

1.Haaverstad R, Vitale N, Tjomsland O, Tromsdal A. Intraoperative color Doppler ultrasound assessment of LIMA-LAD anastomoses in off pump coronary artery bypass grafting. Ann Thorac Surg 2002;74:1390-4.  Back to cited text no. 1      
2.Hol PK, Andersen K, Skulstad H, Halvorsen PS. Epicardial Ultrasonography: a potential method for intraoperative quality assessment of coronary bypass anastomoses? Ann Thorac Surg 2007;84:801-7.  Back to cited text no. 2      
3.Stein H, Smith JM, Robinson JR, Katz MR. Target vessel detection and coronary anastomosis assessment by intraoperative 12-MHz ultrasound. Ann Thorac Surg 2006;82:1078-84.  Back to cited text no. 3  [PUBMED]  [FULLTEXT]  
4.Wolf RK, Falk V. Intraoperative assessment of coronary artery bypass grafts J Thorac Cardiovasc Surg 2003;126:361-7.  Back to cited text no. 4      
5.Gill IS, Gibbon GM, Higginson LA. Minimally invasive coronary artery bypass: a series with early qualitative angiographic follow up. Ann thorac surg 1997;64:710-4.  Back to cited text no. 5      
6.Lytle BW, Loop FD, Cosgrove DM. Longterm [5-12 years] serial studies of internal mammary artery and saphenous vein coronary bypass grafts. J Thorac Cardiovasc Surg 1985;89:248-58.  Back to cited text no. 6      
7.Budde RP. Epicardial ultrasound in coronary artery bypass surgery. Thesis Utrecht university with C summer in Dutch. The Netherlands. UMC Utrecht [University Press] 2005.  Back to cited text no. 7      

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Correspondence Address:
Harish Babu Ravulapalli
Sri Ramachandra Medical College, Porur, Chennai
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0971-9784.69069

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    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]

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