A Comparative Study Between Conventional & Modified Carbo-dissection Techniques for LIMA Harvesting in CABG Patients
Phase: NA
Conditions: Coronary Artery Disease, Coronary Artery Disease With Myocardial Infarction
Sponsor: Government Medical College Kottayam

 
Date 
07/12/23 
From 
Dinesh Kumar Sathanantham 
Senior Resident 
Department of  Cardiovascular and Thoracic Surgery 
Govt. Medical College, Kottayam 
Gandhinagar PO 
Kerala - 686008 
India. 
 
To 
PRS Staff 
Clinicaltrials.gov 
 
Subject:  Request for uploading study protocol and statistical plan of the trial towards 
registry: NCT06155045 
 
Respected Sir/ Madam, 
 
I, Dinesh Kumar Sathanantham, Senior Resident of Cardiovascular and Thoracic 
Surgery the principal investigator request to upload my study protocol and statistical analysis 
plan on the registry number NCT06155045 for the title “A COMPARATIVE STUDY BETWEEN 
CONVENTIONAL TECHNIQUE AND MODIFIED CARBO-DISSECTION FOR LIMA HARVESTING 
IN CABG PATIENTS.” 
 
Thanking you 
Yours Sincerely 
 
 
 
Dinesh Kumar Sathanantham 
Senior Resident 
Department of  Cardiovascular and Thoracic Surgery 
Govt. Medical College, Kottayam 
 

 
 
 
 
A COMPARATIVE STUDY BETWEEN 
CONVENTIONAL TECHNIQUE AND MODIFIED 
CARBO-DISSECTION FOR LIMA HARVESTING 
IN CABG PATIENTS 
 
 
 
BY 
Dr. DINESH KUMAR SATHANANTHAM 
SENIOR RESIDENT 
DEPARTMENT OF CARDIOVASCULAR AND THORACIC SURGERY 
GOVT.MEDICALCOLLEGE, KOTTAYAM 
Mobile: 9094780627 
e-mail: dinesh.sathanantham@gmail.com 
 
 
 
 
 
 
 
 

 
 
 
 
 
BRIEF TITLE: Comparing a New Technique of Combining Carbon-dioxide With 
Electrocautery With Usual Technique of Stand-alone Electrocautery for Taking 
Down Left Internal Mammary Artery for Coronary Artery Bypass(CABG) 
 
SCIENTIFIC 
TITLE: 
A 
COMPARATIVE 
STUDY 
BETWEEN 
CONVENTIONALTECHNIQUE AND MODIFIED CARBO-DISSECTION FOR 
LIMA HARVESTING IN CABG PATIENTS 
 
NCT Number: NCT06155045 
Unique Protocol ID: 95/2020 
Document Date: 11/11/2020 
 
INTRODUCTION: 
CABG(coronary artery bypass grafting) is still considered the most versatile re-
vascularisation procedure for CAD and often exemplary in the  setting of TVD(triple vessel 
disease) with diabetes.1 In the revascularization of LAD(Left Anterior Descending artery), 
LITA(Left Internal Thoracic Artery) or LIMA (Left Internal Mammary Artery) is the artery 
of prime importance, used. The dissection of the same from the surrounding fascial 
attachments, based on its position anterior to the endothoracic fascia and transverses thoracis 
is a tedious task and the venous & arterial branches are easily torn if traction is applied.2 
Various techniques have been used for the dissection of LIMA, still studies say 40% 
of LITA gets damaged or has a poor flow, owing to spasm and injury.3 To curtail this, various 
vaso-active agents have been studied to reduce stress and increase the flow rate of LIMA, 
during dissection.2C02, because of the hypercapnic veno-dilator properties was utilized in a 
few studies from 1988.4and proved to have promising results, though the instrumentation for 
the same has not been devised. We have planned to use a modified technique as per a case 
report done by shigu et al. (2017)5 in a larger study; to study the efficacy of carbo-dissection 
for LIMA harvesting. 

 
 
 
 
RESEARCH QUESTION 
 
Does the use of modified carbodissection result in less operative time and increased 
flow rate in harvesting of LIMA. 
 
AIMS &OBJECTIVES:  
AIM: To study the flow rate and operative time of modified carbo-dissection for 
harvesting of Left Internal Mammary artery. 
Objectives of the study: 
1. To study the first flow in one min, operative time of conventional pedicled technique 
and modified carbodissection technique for harvesting LIMA 
 
 
TYPE OF STUDY 
Prospective comparative study  
 
PERIOD OF STUDY 
: 
Jan 2021- Jan 2022 
 
DURATION OF STUDY: 12 months 
 
PLACE OF STUDY  
 
:  Department of Cardiovascular and Thoracic Surgery, 
 
 
 
 
 
Government Medical College, Kottayam 
STUDY POPULATION 
Patients undergoing elective CABG in GMC, Kottayam with requirement of LIMA 
harvest in the dept. of Cardiovascular & Thoracic surgery, Govt. Medical college, 
Kottayam. 
 
RESEARCH APPROACH 
Quantitative 
 

 
 
 
Statistical analysis:  
Data will be entered into Microsoft excel data sheet and will be analyzed using SPSS 22 
version software. Categorical data will represented in the form of Frequencies and 
proportions. Chi-square will be the test of significance. Continuous data will be represented 
as mean and standard deviation. Independent t test will be the test of significance to identify 
the mean difference between two groups. p value <0.05 was considered as statistically 
significant. 
Sample Size:6-9 Was estimated by using the difference in first free flow measurement in the 
carbon dioxide–insufflated internal thoracic arteries in Group 1 28 ± 19 mL/min and in group 
2 was 60 ± 32 mL/min; from the study Mehmet O zkan et. al.4 Using these values at 99% 
Confidence limit and 90% power sample size of 21 was obtained in each group by using the 
below mentioned formula and Med calc sample size software. With 10% non-response 
sample size of 21 + 2.1 ≈ 23 cases will be included in each group.  
 
 
 
 
Sample Size Estimation Formula:  
 
 
 
 
 
 
 
 
 
 
 

 
 

Sample Size For Comparing Two Means 
Input Data 
  
Confidence Interval (2-sided) 
99% 
Power 
90% 
Ratio of sample size (Group 2/Group 1) 
1 
  
Group 1 
Group 2  
Mean difference1 
Mean 
28 
60 
 
-32 
Standard deviation 
19 
32 
 
Variance 
361 
1024 
 
Sample size of Group 1 
21 
 
Sample size of Group 2 
21 
 
Total sample size 
42 
 
1 Mean difference= (Group 1 mean) - (Group 2 mean) 
 
 
 
 
Randomization: 
Computer generated randomization using www.randomization.com for the allotment of case 
between two groups, details as mentioned below. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
A Randomization Plan 
from 
http://www.randomization.com 
 
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46 subjects randomized into 1 block 
To reproduce this plan, use the seed 29386 
along with the number of subjects per block/number of blocks 
and (case-sensitive) treatment labels as entered originally. 
Randomization plan created on 12/2/2020, 11:36:59 PM 
 
 
 
 
HYPOTHESIS: 
Use of modified carbodissection for harvesting will result in better flow rate and less 
operative time. 
 
 
MATERIALS AND METHODS 
 
STUDY PROCEDURE 
After taking informed consent, patients with CAD with indication for 
CABG and satisfying the inclusion criteria will be admitted, data will be 
collected on predefined  proforma. 
Methodology 
Following consultation to our department, after a detailed history and 
clinical examination,patients with CAD, being planned for CABG, will be 
subjected to a detailed pre-op Echocardiogram and coronary angiogram. After 
necessary pre-op assessment, patient will be taken up for the surgery. Invasive 
monitoring will be done.  After median sternotomy, pericardiectomy, LIMA 
dissection will be done by the planned method as in: The modified 
carbodissection technique is performed using an improvised instrument that 
combines an electrocautery pencil (ValleylabTM Force FX electrocautery Pencil, 
Covidien, USA) with a CO2 mister blower (PerfX® Heart Lung pack 
Blower/Mister Kit, B L lifesciences, Noida,India) that is routinely used in off-
pump CABG. The instruments are fixed together using  silk ties. The 
electrocautery is used in the coagulation mode at a setting of 10 to 15. The CO2 

flow is set at 2 to 3 liters/minute. Saline flow is adjusted to a level where it does 
not hinder the effective coagulation but still prevents drying and desiccation of 
the tissues.5 
Following dissection of LIMA by the above mentioned technique, flow of  
blood from the harvested LIMA, for one whole minute is noted.  The operative 
time required for the dissection of LIMA will be noted and entered. 
 
 
 
 
STUDY TOOLS 
Structured Proforma 
 Instruments –  
1. Gas blower/mister (PerfX® Heart Lung pack Blower/Mister Kit, B L 
lifesciences, Noida, India) 
2. Electrocautery (ValleylabTM Force FX electrocautery Pencil, Covidien, 
USA) 
3. C02 supply 
 
 
INCLUSION CRITERIA 
1. Elective CABG 
2. Hemodynamically stable CAD patients 
 
EXCLUSION CRITERIA 
1. Re-operation, previous sternotomy (where LIMA is already dissected) 
2. concomitant valve operation, ventricular aneurysm resection  
3. other additional major cardiac procedures 
4. Patients with chronic obstructive pulmonary disease 
 
 

DATA MANAGEMENT AND STATISTICAL ANALYSIS 
Data will be coded and entered in Microsoft Excel and analyzed using IBM 
SPSS software Qualitative data will be presented using percentage and 95% CI, 
and analyzed with chi square test of independence. Quantitative data will e 
presented using mean and standard deviation. 
Independent t-test will be used for comparison between groups. Pearson’s 
correlation coefficient will be used to test the relationship between 
parameters. A p value < 0.05 is used as threshold for significance. 
 
 
 LIMITATIONS OF STUDY: 
Small sample size 
Skill dependent 
 
 
PRINCIPAL INVESTIGATOR:.Dinesh Kumar Sathanantham 
 
 
REVIEW OF LITERATURE 
 
 
Over the period of years, the internal thoracic artery or internal mammary 
artery has become the main conduit of choice for coronary artery bypass 
grafting; based on its superior patency rates and longer survival period.4 A 
proper functioning LIMA grafted to LAD, provides a patency rate of 98% at 1 
year and 94% at 7 years, compared to a patency rate of only 75% at 5 years for 
saphenous vein graft.1 The operative technique used for the dissection of ITA, 
might affect the flow capacity4 Different techniques have been tried over the 
period of years for LIMA dissection and most commonly used are the pedicled, 
skeletonised/semi-skeletonised technique. But still studies have shown a failure 
rate of LIMA failure is high at 40%.3 Nevertheless, the thoracic wall damage 
and sternal infection are present. 

 
To counter-act this reduced flow rates due to spasm and injury, various 
vaso-active agents have been used in the yester years. The most commonly used 
is a topical (or) intra-luminal vaso-dilator namely papaverine. Use of gaseous 
vaso-dilators, has not been studied in detail and the safer of all is Carbon 
dioxide(C02), due to its easy diffusion and non inflammable properties, has 
more 
vaso-dilatory 
properties 
Both in 
vitro and in 
vivo studies 
have 
demonstrated a rightward shift of the oxygen–hemoglobin dissociation curve 
after administration of CO2. Sakai et al. described this as an “artificial Bohr-
effect”. This was responsible for the increased partial pressure of oxygen and 
the decreased pH.7 
 
A few studies have combined the use of C02 insufflation in LIMA 
dissection, as a gaseous vaso-dilator to avoid injury. In 1988, Myles Edwin Lee, 
used the C02 insufflation technique called carbo-dissection and in this 
technique, C02 is injected into the endothoracic fascia to form subpleural 
emphysema bleb, to aid in the dissection of LIMA. Methodology used was 
Cardiac pacing lead introducers (8F to 12F), initiallymodified by placing four to 
six side holes within a centimetre of the tip, are now used as obtained from 
themanufacturer but with the tip flattened to give an ellipticalcross-section for 
easy passage through tissue. An 8Fintroducer, now our standard, is attached to a 
commerciallyavailable gas delivery system (Gish Biomedical,Santa Ana, CA), 
which includes a Luer lock connector,0.6-cm (%-inch) polyvinylchloride tubing, 
and a 0.45-kmgas filter (Model No., Gas-1) (Fig l), all of which are 
brought to the operative field with the pump tubing andconnected to a tank of 
C02 by the perfusionist. A small incision is made in the endothoracic fascia 
medial to the ITA pedicle and adjacent to the superiorborder of a costal 
cartilage. The incision should bejust long enough to accommodate the 
introducer andnot allow gas leaks into the atmosphere. A flow of 4 to 6L/min 
suffuses the chest wall for distances of 10 cm laterally,superiorly, and inferiorly, 
in approximately 2 seconds. In another study conducted by ozakan et al, 

employed the use of subpleural emphysema with 24G needle, thereby forming a 
bleb to clearly dissect. The study was done on 28 consecutive patients and had 
no incidence of complications. 
 
 
An another descriptive study by O¨ zkan et al, described the use of carbo-
dioxide insufflations in 350 patients and no incidence of complications was 
reported.8 As this technique seems tedious and injury to LITA, due to the 
insufflate needle is still present. An improvised technique as described by shigu 
et al5,  published in 2017, which uses a modified technique on carbo-dissection : 
technique is performed using an improvised instrument that combines an 
electrocautery pencil with a CO2 mister blower. The instruments are fixed 
together using silk ties. The electrocautery is used in the coagulation mode at a 
setting of 10 to 15. The CO2 flow is set at 2 to 3 liters/minute. This method is 
relatively easier to perform, with no excessive use of resources. Therefore this 
was taken to be used in own study of dissection of  LIMA. 
 
 
In study by O¨ zkan et al, done in 2003, showed significantly high flow 
rates of  68+/ _ 46 mL/min in carbondioxideinsufflated group, compared to 53+/ 
_ 32 mL/min in the conventional group and lesser operative time in carbon 
insufflated group.4 
 
 
 
 
REFERENCES 
1. Talal Al Atassi, Hadi D Toeg, Vincent Chan, Marc Ruel. Coronary Artery 
Bypass Grafting,In: Selke Frank W, Del Nido Pedro, Swanson, Scott J. 
Sabiston& Spencer surgery of the chest.(19ed.);2016. P 1551-2. 

2. Lee ME.Carbodissection of the internal thoracic artery. J 
ThoracCardiovasc Surg. 2005 May;129(5):1203-4;  
3. Blake KL, Watt PAC, Smith JMT, De Souza AC, Spyt T J, Thurston H. 
Randomized comparison of ultrasonic aspiration versus conventional 
electrocautery for dissection of the human internal thoracic artery. J 
ThoracCardiovascSurg 1996;111: 1194-9). 
4. Ozkan M1, Koramaz I, Ulus AT, Tavil Y, Filizlioglu H, Baykan 
EC, Eryilmaz S, Inan B, Katircioglu SF, Ozyurda U. Effect of carbon 
dioxide insufflation on free internal thoracic artery flows: is it a 
vasodilator? 
5. Gilbert S, Singh D, Sivakumar MK. Modified carbodissection: A new 
technique for harvesting the internal mammary artery. Multimed Man 
Cardiothorac Surg. 2017;2017:10.1510/mmcts.2017.018. Published 2017 
Oct 29. doi:10.1510/mmcts.2017.018. 
6. George w. snedecor. statistical methods, 4th edition, lowa, u.s.a.:oxford 
&ibh publishing co.;c1946, chapter-17, design and analysis of 
samplings,p-456-458. 
7. Sakai Y, Miwa M, Oe K, et al. A novel system for transcutaneous 
application of carbon dioxide causing an "artificial Bohr effect" in the 
human body. PLoS One. 2011;6(9):e24137. 
doi:10.1371/journal.pone.0024137 
8. Lee ME. (1997, March). Carbodissection of the internal thoracic artery 
pedicle [Letter to the editor]. The journal of thoracic and cardiovascular 
surgery. Retrieved 
fromhttps://www.annalsthoracicsurgery.org/article/S0003-
4975(10)64671-1/pdf