FIELD OF THE INVENTION
[001] The present invention relates to the field of medical science, and more particularly,
the present invention relates to the comparison of immediate postoperative complications in
using the left internal mammary artery vein versus only the vein as a conduit in patient
sundergoing off-pump coronary artery bypass grafting.
BACKGROUND FOR THE INVENTION:
[002] The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known, or part of the common general knowledge in any jurisdiction as of the priority date of the application. The details provided herein the background if belongs to any publication is taken only as a reference for describing the problems, in general terminologies or principles or both of science and technology in the associated prior art.
[003] Adam Hammer in 1876 established the pathophysiology of coronary artery disease (CAD), establishing that angina was caused by interruption of coronary blood supply and that myocardial infarction occurred after the occlusion of at least one coronary artery. Coronary artery bypass grafting (CABG) is a procedure where section of a blood vessel is grafted from the aorta to the coronary artery to bypass the blocked section of the coronary artery, thus improving the blood supply to the heart. In 2004, CAD was the leading cause of death in India, leading to 1.46 million deaths. There is always a debate between percutaneous coronary intervention (PCI) and surgical revascularization. The surgical revascularization provides better long-term results, thus favoring CABG over PCI for revascularization.
[004] Preoperative clinical condition has also been associated with postoperative outcome and the preoperative presence of angina is a positive predictor of improved life expectancy despite impaired left ventricular (LV) function as compared to patients with heart failure symptoms and dyspnea. CABG with the use of the left internal mammary artery (LIMA) and saphenous vein grafts is the standard and widely accepted surgical approach in the treatment of CAD. Vasospasm of the arterial grafts is a serious perioperative complication and may result in IMA hypoperfusion syndrome with its high mortality. Harvesting of both right and left IMAs, particularly in the diabetic patient, is associated with an increased incidence of sternal wound infections because in the process of IMA dissection, the sternal branches are sacrificed so sternal blood supply is jeopardized. CABG with the use of arterial conduits and the sequential.
[005] anastomotic techniques have been the trend. Harvesting of bilateral mammary arteries is more time-consuming and may result in increased operative time. Morbidities such as atrial fibrillation, ventricular arrhythmias, renal dysfunction, and stroke after CABG are more common in patient with poor LV function. Intensive care unit stay and mean hospital stay are also longer in these low ejection fraction (EF) patients and contribute to postoperative morbidity and mortality. The use of IMA as a conduit has proven to be superior for its long-term patency rates, whereas saphenous vein graft being larger caliber vessel achieves superior flow dynamics in the early postoperative period. Off-pump technique has reduced the complications associated with extracorporeal circulation and heart–lung machine, thus contributes to better surgical outcome. Although many studies have demonstrated the long-term advantage of using mixed conduits (LIMA + vein) instead of only venous conduits in terms of graft patency, a very few studies have compared the incidence of postoperative cardiac complications. Our present study aims to compare the above-mentioned parameters in both the groups.
[006] In light of the foregoing, there is a need for the Comparison of immediate postoperative complications in using the left internal mammary artery vein versus only the vein that overcomes problems prevalent in the prior art.

OBJECTS OF THE INVENTION:
[007] Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
[008] The principal object of the present invention is to overcome the disadvantages of the prior art by providing the Comparison of immediate postoperative complications in using left internal mammary artery vein versus only vein.
[001] An object of the present invention is to provide the Comparison of immediate postoperative complications in using the left internal mammary artery vein versus only vein, wherein the study is to compare the immediate postoperative cardiac complications in patients undergoing off-pump coronary artery bypass grafting (OPCABG) using mixed (arterial and venous grafts) versus only venous grafts and to compare the requirement of packed red cell units and intra-aortic balloon pump (IABP) in both the groups.
[002] Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.

SUMMARY OF THE INVENTION:
[003] The present invention provides a comparison of immediate postoperative complications in using the left internal mammary artery vein versus only the vein.
[004] In one aspect of the present invention, a comparison of immediate postoperative complications in using the left internal mammary artery vein versus only vein comprises patients diagnosed with triple-vessel coronary artery disease (CAD) undergoing OPCABG with an ejection fraction (EF) of more than 30%. Patients who have undergone prior CABG, EF <30%, preexisting valvular heart disease, any evidence of pulmonary hypertension, preoperative IABP, any history of neurological dysfunction, left atrium size more than 5.5 cm, and history of coagulation disorder were excluded from the study.
[005] In another aspect of the present invention, the most common immediate postoperative cardiac complication observed was atrial fibrillation followed by ventricular arrhythmias in both groups.
[006] In another aspect of the present invention, there was no statistically significant difference in complication rate between the two groups.
[007] In another aspect of the present invention, the postoperative requirements of IABP and requirements of blood products were also similar in both groups.
[008] In another aspect of the present invention, the patients undergoing off-pump CABG have similar immediate postoperative complications irrespective of the type of conduit used.
[009] In another aspect of the present invention, the fifty new patients were included in the study.

DETAILED DESCRIPTION OF DRAWINGS:
[010] While the present invention is described herein by way of example using embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments of drawing or drawings described and are not intended to represent the scale of the various components. Further, some components that may form a part of the invention may not be illustrated in certain figures, for ease of illustration, and such omissions do not limit the embodiments outlined in any way. It should be understood that the drawings and the detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claim.
[011] As used throughout this description, the word "may" is used in a permissive sense (i.e. meaning having the potential to), rather than the mandatory sense, (i.e. meaning must). Further, the words "a" or "an" mean "at least one” and the word “plurality” means “one or more” unless otherwise mentioned. Furthermore, the terminology and phraseology used herein are solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers, or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Any discussion of documents, acts, materials, devices, articles, and the like are included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention.
[012] In this disclosure, whenever a composition or an element or a group of elements is preceded with the transitional phrase “comprising”, it is understood that we also contemplate the same composition, element, or group of elements with transitional phrases “consisting of”, “consisting”, “selected from the group of consisting of, “including”, or “is” preceding the recitation of the composition, element or group of elements and vice versa.
[013] The present invention is described hereinafter by various embodiments with reference to the accompanying drawing, wherein reference numerals used in the accompanying drawing correspond to the like elements throughout the description. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the following detailed description, numeric values and ranges are provided for various aspects of the implementations described. These values and ranges are to be treated as examples only and are not intended to limit the scope of the claims. In addition, several materials are identified as suitable for various facets of the implementations. These materials are to be treated as exemplary and are not intended to limit the scope of the invention.
[014] The present invention provides a comparison of immediate postoperative complications in using the left internal mammary artery vein versus only the vein.
[015] The study was carried out over a period of 12 months. This is prospective, observational, analytical study. All patients attending our hospital for bypass surgery during the study period were considered as sample. During this period, 50 patients were selected for the study which fulfilled the following inclusion and exclusion criteria as follows:
Inclusion criteria
[016] Patients diagnosed with triple-vessel CAD requiring off-pump surgical myocardial revascularization with a left ventricle EF (LVEF) of more than 30%.
Exclusion criteria
[017] Prior cardiac surgery for myocardial revascularization, LVEF <30%, any preexisting valvular heart disease, any evidence of pulmonary hypertension, CABG with the use of cardiopulmonary bypass machine, preoperative IABP, patients with left atrium size more than 5.5 cm, or patients with a history of coagulation disorder. All selected patients were divided into two groups alternatively to receive either mixed LIMA + veins or only veins as conduits.
[018] In the first Group A (mixed conduits group), pedicle LIMA and reverse saphenous vein were used as conduits. In Group B (venous conduits group), reverse saphenous vein only was used as conduit. Demographic and anthropometric indices were recorded for all patients which included age, sex, and other demographic details. Preoperatively, all patients underwent routine blood and other investigations.
[019] Antiplatelets (aspirin and clopidogrel) were stopped 3 days before surgery. Induction of anesthesia was carried out using standard high narcotic induction in all patients with an aim to minimize hemodynamic changes during induction of anesthesia as per the standard protocol of the institute. The procedure performed was off-pump CABG. All patients were given heparin after harvesting of conduits, and the same was reversed with protamine with a ratio of 1:1. At the end of surgery, pleural and mediastinal chest tubes were placed and drainage was carefully monitored and compared. Postoperatively, all patients underwent elective controlled ventilation with routine monitoring as for any cardiac surgical case. A note of certain complications was documented for study purpose which included atrial fibrillation, ventricular arrhythmias, and IABP requirement. Need for blood transfusion and actual unit transfused was noted down with a target of keeping the hemoglobin level more than 10 g% or a hematocrit above 30. The duration of ventilation was depending on clinical condition, bleeding status, and fitness criteria for extubation as per institute protocols.
[020] Continuous variables are presented as mean ± standard deviation, and categorical variables are presented as absolute numbers and percentages. The comparison of normally distributed continuous variables between the groups was performed using Student’s t-test. Nominal categorical data between the groups were compared using the Chi-squared test or Fisher’s exact test as appropriate. P < 0.05 was considered statistically significant.
[021] The mean age between the two groups was 58.88 ± 6.86 (Group A) and 63.04 ± 8.96 years (Group B) (P = 0.079). The mean body mass index (BMI) (kg/m2) of Group A was 25.75 ± 4.06 kg/m2 while of Group B was 23.77 ± 3.03 kg/m2 (P = 0.056) [Table 1].

[022] There were 80% males and 20% females in Group A and 88% males and 12% females in Group B, and gender distribution was comparable (P = 0.440). The prevalence of diabetes was 44% in Group A and 32% in Group B (P = 0.556) while that of hypertension was 24% in Group A and 28% in Group B (P = 0.747). It was observed that there were 24% patients in Group A and 44% patients in Group B with NYHA Class I and II symptoms, whereas there were 76% patients in Group A and 56% patients in Group B with Class III and IV symptoms (P = 0.136).
[023] It was observed that under in Group A, mean hemoglobin value was 12.18 (±1.95) gm%, whereas in Group B, it was 12.46 (±1.99) g%. Mean creatinine levels were 1.01 ± 0.30 and 0.95 ± 0.28, respectively, in both the groups. It was observed that there was no significant difference in routine investigations between the two groups. The mean drain output (blood loss) in the first 24 h of Group A was 295.56 ± 145.45 ml while that of Group B was 265.20 ± 144.60 ml, although the drain output was more in Group A, the difference was not statistically significant between the two groups (P = 0.463).
[024] The most common complication in both the groups was atrial fibrillation (AF) with the incidence of 36% in Group A and 16% in Group B (P = 0.196). It was followed by ventricular arrhythmias (12% and 8%, respectively, with P = 1.000). The most common ventricular arrhythmias seen were ventricular premature beats, bigeminy rhythm, or nonsustained short runs of ventricular tachycardia. Most of these were treated with correction of electrolytes and occasional bolus dose of IV lignocaine. Reexploration was done in one case in Group A who was on antiplatelets for acute chest pain, while there was no incidence of reexploration in Group B. IABP was required in two patients in each group with low EF and AF and they recovered eventually. The requirement of packed red blood cell units was also similar in both the groups. It was observed that there was no mortality in either group.
[025] In 1910, Alexis Carrel was the first to describe CABG procedure. Goetz R in 1960 first reported CABG using the IMA in humans. From 1962 to 1967, human CABG using autogenous saphenous vein grafts was performed by cardiac surgical groups by, namely, Sabiston D (1962), Garrett H (1964), Kahn D (1966), and Favaloro R (1967) and many more. Thoracoscopic harvesting of the LIMA was reported in 1998 by Duhaylongsod et al. and in the present scenario, more and more surgeons are moving toward minimally invasive and robotic surgical approaches. Similar results were observed by Edwards et al. Majority of patients in their study were in age group of 50–70 years.Their study had 79% male and 21% female patients in mixed group whereas 69% males and 31% females in venous group. In a study conducted by Jegaden et al., the average age in LIMA group was 66 years and in venous group was 68 years.
[026] The mean age in their study in both the groups was higher as compared to our study, probably because higher prevalence of CAD in Indian population and also at a younger age. In patients <70 years, the incidence of CAD-related deaths in India is 50%, whereas only 22% in Western countries. The mean BMI (kg/m2) of Group A was 25.75 ± 4.06 kg/m2 while of Group B was 23.77 ± 3.03 kg/m2 (P = 0.056), representing similar characteristics of patients in both groups, similar observation was in the studies conducted by Jegaden et al. and Mehsood et al. with no difference in BMI in both the groups. In our study, the prevalence of diabetes was 44% and 28% and the prevalence of hypertension was 24% and 48% in Group A and B, respectively, (P = 0.239 and 0.077, respectively). Edwards et al. noticed the prevalence of diabetes were 22.02% patients in LIMA group and 20.25% patients in non-LIMA group.
[027] About 48.70% were hypertensive in mixed group and 45.45% were hypertensive in venous group. The prevalence of diabetes and hypertension was 24.7% and 50.7%, respectively, in IMA and venous groups (P = 0.99) in study conducted by Jegaden et al. These findings are in contrast to the results of our study. Mehsood et al. in his study observed that there were 26% diabetic patients in both mixed and venous groups (P = 1.000) and there were 50% hypertensives in mixed group and 34% hypertensives in venous group (P = 0.105). This observation is in contrast with our study where we observed that number of hypertensives were more in venous group. Jegaden et al. and Mehsood et al. in their studies observed that mean blood loss was significantly more in those patients where LIMA was harvested as conduit.
[028] Bleeding after CABG surgery is a concern to all practicing cardiac surgeons. Some surgeons believe that taking down the LIMA leaves a raw bed under the chest wall that has the potential to bleed after the chest is closed. In addition, there is the possibility of bleeding from intercostal branches of the LIMA itself. The chance of bleeding increases if patient is on platelet inhibitors. In our study, IABP was required in two patients (8%) in each group who had low EF and AF (they recovered
[029] eventually following IABP placement). Edwards et al. and Choudhary et al. in their study observed that IABP requirement was 5.53%–12.9% in LIMA group and 10.18%–17.2% in venous group. Results obtained in our study were comparable with their study. Karthik et al. observed that in patients undergoing CABG, the IABP support postoperatively was required in 2.4% patients in LIMA group and 2.2% in non-LIMA group. In contrast to their study, IABP requirement in our study was higher. Jegaden et al. in their study also observed that there was no difference in IABP requirement in arterial or venous group. In a study conducted by Topkara et al., patients were stratified into four groups according to EF. They concluded that requirement of IABP and LV assist device (during or after surgery) was significantly higher in patients with low EF. In our study also, we found that postoperative requirement of IABP was more in patients with low EF in both the groups.
[030] The disclosure has been described withreference to the accompanying embodiments herein and the various features and advantageous details thereof are explained witherence to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
[031] We conclude that the most common immediate postoperative cardiac complication was AF followed by ventricular arrhythmias in both the groups. There was no statistically significant difference between the complications compared. Postoperative requirements of IABP and requirements of blood products were also similar in both groups. Further studies with long-term follow-up are required to confirm the above findings.
[032] The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the scope of the embodiments as described herein.

We Claim:

1) A Comparison of immediate postoperative complications in using the left internal mammary artery vein versus only vein, the comparison comprises patients diagnosed with triple-vessel coronary artery disease (CAD) undergoing OPCABG with an ejection fraction (EF) of more than 30%. Patients who have undergone prior CABG, EF <30%, preexisting valvular heart disease, any evidence of pulmonary hypertension, preoperative IABP, any history of neurological dysfunction, left atrium size more than5.5 cm, and history of coagulation disorder were excluded from the study.
2) The comparison as claimed in claim 1, wherein the most commonimmediate postoperative cardiac complication observed was a trial fibrillation followed by ventriculararrhythmias in both groups.
3) The comparison as claimed in claim 1, wherein there was no statistically significant difference in complication rate between the two groups.
4) The comparison as claimed in claim 1, wherein the postoperative requirements of IABP and requirements of blood products were also similar in both groups.
5) The comparison as claimed in claim 1, wherein the patients undergoing off-pump CABG have similar immediate postoperative complications irrespective of the type of conduit used.
6) The comparison as claimed in claim 1, wherein the fifty new patients were included in the study.