STUDY OF POSTERIOR INTERVENTRICULAR ARTERY IN HUMAN CADAVERIC HEARTS

Address for Correspondence: Dr. Komala Nanjundaiah, Associate Professor, Department of Anatomy, M.S.Ramaiah Medical College, M.S.R Nagar, Bangalore 560054, Karnataka, India. E-Mail: komas2001@yahoo.com Back ground: Human heart is supplied by coronary arteries. Variations in the branching pattern of coronary arteries can affect the blood supply to the heart. Context: Origin of posterior interventricular artery determines the coronary dominance. Prognosis of inferior wall infarcts is related to coronary dominance. Purpose: The present study was conducted in 60 specimens of human cadaveric hearts and observed for number, origin, and level of termination of posterior interventricular artery. Results: Present study was conducted in 60 specimens and right coronary dominance was observed in 91.7%. The incidence of left coronary dominance was observed in 6.7% and co-dominance was found in 1.7%. Conclusion: Posterior interventricular artery has special importance as it determines the coronary dominance. The blood supply of the inferior myocardium depends on the dominance. Hence awareness of these variations plays an important role in treating inferior wall infarcts. Also awareness of coronary artery variations is important during interventions like imaging by conventional catheters.

its branches were dissected on the posterior surface of heart.The left coronary arteries and their branches were identified.The PIVA, which passes along posterior interventricular groove, was found and its origin was noted.The course of PIVA up to the termination was traced.Any variation in origin and termination was recorded.
Based on the origin of PIVA, whether from RCA or LCA or both, the coronary dominance was determined.The data was then tabulated.Statistical analysis was done.Ethical clearance for the study was obtained from the institutional ethical review board.
Inclusion criteria: Formalin fixed heart specimens with intact coronary arteries irrespective of age, sex or race.
Exclusion criteria: Lacerated or injured heart specimens with damaged coronary arteries, hearts with any surgeries of coronary arteries, maldeveloped hearts were excluded.

MATERIALS AND METHODS
Source of data: Randomly selected 60 formalin fixed hearts (preserved heart specimens and hearts from cadavers which were used for dissection teaching) were obtained from the Department of Anatomy, M.S Ramaiah Medical College and few other medical colleges in Bangalore.These fixed heart specimens were dissected and studied over a period of two years.Study design: Cross-sectional study Sample size: Based on a study "Variations in coronary arterial system in cadaveric human heart" [6], it was found that 66% was right dominant and 23% was left dominant.So with power of 80% and confidence level of 95%, the requisite sample size was estimated to 60 specimens.
Steps of dissection: The hearts from the cadavers were removed by cutting the ribs and sternum.The great vessels were ligated at two ends and then cut in between.The parietal pericardium was incised and heart along with great vessels was taken out of the pericardial cavity.All hearts were washed under running tap water to remove blood clots.The hearts were preserved in 10% formalin solution.All the hearts were tagged numerically.Coronary arteries and their branches were dissected in all hearts.Fat was removed from the coronary sulcus.Right coronary artery was traced from its origin, till it turns on the posterior surface of the heart.Then

RESULTS
The present study was conducted in 60 specimens of cadaveric hearts and observed for number, origin, and level of termination of PIVA.Coronary dominance was noted based on the origin of PIVA and tabulated as follows.The termination of PIVA way down the posterior interventricular sulcus (PIVS) was noted as follows.deaths.Inferior wall infarcts of the heart is related to dominance. 5Outcome of these infarcts can be determined by the extent of damage of the left ventricular myocardium.This is based on blood supply to the left ventricle.In right dominant hearts most of the left ventricle is supplied by left coronary artery.But in left dominant hearts the area supplied by left coronary artery is even more.Some anomalies of the coronary arteries can also cause sudden death especially in young athletes. 8Hence t horough knowledge of normal and variant anatomy of coronary arteries is a prerequisite for clinicians to treat congenital, acquired, metabolic or degenerative heart diseases. 3resent study was conducted in 60 specimens and right coronary dominance was observed in 55 cases (91.7%) which is similar with other studies. 3,9,10,11,12,The incidence of left coronary dominance in present study was 6.7% which was also similar to earlier studies. 10,11,13,14In the present study, Co-dominance was found in 1.7%.
Comparison of the results of the present study with the results of the various other authors is as follows.

INTRODUCTION
International Journal of Anatomy and Research, Int J Anat Res 2017, Vol 5(3.2):4238-41.ISSN 2321-4287 DOI: https://dx.doi.org/10.16965/ijar.2017.295circumflex branch of left coronary artery (LCA).Branches of right coronary artery are anterior atrial rami (sinu-atrial nodal artery), ventricular rami (right conus artery and right anterior ventricular rami, right posterior ventricular rami, posterior interventricular branch and right posterior atrial rami.The left coronary artery takes origin from left posterior aortic sinus.It divides into anterior interventricular, circumflex The heart is a hollow conical muscular organ, situated in the middle mediastinum.It is covered by pericardium.The heart which supplies blood to the entire body has to be supplied by coronary arteries.These coronary arteries are right and the left [1].The right coronary artery (RCA) takes origin from anterior aortic sinus and terminates by anastomosing with and diagonal artery [2].Variations in the branching pattern of coronary arteries mainly affect the blood supply of the diaphragmatic surface of the ventricles.Based on the origin of posterior interventricular artery (PIVA), the relative dominance is described.If the PIVA arises from RCA, it is right dominance.If PIVA arises from LCA it is left dominance.If PIVA arises from both LCA and RCA it is termed as balanced pattern.Knowledge of normal and variant anatomy and anomalies of coronary arterial circulation becomes essential for treating heart diseases to get better outcomes [3].Dominance becomes a major part in assessing prognosis of coronary artery disease [4].Compared to right and mixed types of dominance, Left dominance is fatal [5].The present study is done to note the origin and termination of PIVA.Based on the origin of PIVA, coronary dominance is documented.
Heart contracts about one lakh times in a day.Coronary arteries which supply the heart begin to develop in utero around 3 rd week of embryogenesis.The steps of development include vasculogenesis, angiogenesis, arteriogenesis and remodeling.Due to this complexity involved during the development of coronary arteries, variations and anomalies are frequently seen. 7Anomalous origin of these arteries has important clinical manifestations.Dominance pattern of heart plays key role in various clinical conditions.On comparing with right & mixed types of dominance, left dominance shows increased

CONCLUSION
ABBREVIATIONS

Table 2 :
Showing level of termination of PIVA originated from RCA.

Table 4 :
Comparison of the origin of PIVA.The difference in percentage could be due to difference in sample size and different racial and geographical population.In present study PIVA which originated from the RCA terminated at ¼ way down PIVS in 28.57%, ½ way down PIVS in 37.5%, ¾ way down PIVS in 23.21% and at apex in 10.71%.25% of the PIVA which originated from LCA t12minated at ¾ way down PIVS, another 75% terminated at ½ way down PIVS.When compared with the findings of the other authors termination of PIVA depicted no definite pattern.3,10,12KannanSubramanian, Komala Nanjundaiah.STUDY OF POSTERIOR INTERVENTRICULAR ARTERY IN HUMAN CADAVERIC HEARTS.