Left Ventricular Summit-Concept, Anatomical Structure and Clinical Significance

Abstract

The left ventricular summit (LVS) is a triangular area located at the most superior portion of the left epicardial ventricular region, surrounded by the two branches of the left coronary artery: the left anterior interventricular artery and the left circumflex artery. The triangle is bounded by the apex, septal and mitral margins and base. This review aims to provide a systematic and comprehensive anatomical description and proper terminology in the LVS region that may facilitate exchanging information among anatomists and electrophysiologists, increasing knowledge of this cardiac region. We postulate that the most dominant septal perforator (not the first septal perforator) should characterize the LVS definition. Abundant epicardial adipose tissue overlying the LVS myocardium may affect arrhythmogenic processes and electrophysiological procedures within the LVS region. The LVS is divided into two clinically significant regions: accessible and inaccessible areas. Rich arterial and venous coronary vasculature and a relatively dense network of cardiac autonomic nerve fibers are present within the LVS boundaries. Although the approach to the LVS may be challenging, it can be executed indirectly using the surrounding structures. Delivery of the proper radiofrequency energy to the arrhythmia source, avoiding coronary artery damage at the same time, may be a challenge. Therefore, coronary angiography or cardiac computed tomography imaging is strongly recommended before any procedure within the LVS region. Further research on LVS morphology and physiology should increase the safety and effectiveness of invasive electrophysiological procedures performed within this region of the human heart.

Keywords: cardiac anatomy; left ventricular summit; septal perforator; ventricular arrhythmia.

Figure 1

The left ventricular summit (LVS) with marked boundaries. (A) The LVS in heart cadaveric specimen; (B) LVS in medical imaging visualization (angio-computed tomography rendered image). Red asterisk = inaccessible area, green asterisk = accessible area, violet asterisk = septal summit, black asterisk = aortic–mitral continuity, yellow asterisk = apex of LVS, AIV = anterior interventricular vein, AV = aortic valve, Cx = circumflex branch of left coronary artery, GCV = great cardiac vein, LAA = left atrial appendage, LAD = left anterior descending artery, LCA = left coronary artery, MV = mitral valve, PT = pulmonary trunk, PV = pulmonary valve, SP = septal perforator.

Figure 2

Photographs of cadaveric heart specimens showing the left ventricular summit (LVS) area with overlying epicardial adipose tissue. (A) Section through the septal margin of the LVS; (B) view of the LVS after adipose tissue removal; (C) section through the LVS showing the abundance of the adipose tissue. Black asterisk = aortic–mitral continuity, yellow asterisk = apex of LVS, AIV = anterior interventricular vein, CS = coronary sinus, Cx = circumflex branch of left coronary artery, GCV = great cardiac vein, LAA = left atrial appendage, LAD = left anterior descending artery, LCC = left coronary cusp, LIPV = left inferior pulmonary vein, LMV = left marginal vein, LSPV = left superior pulmonary vein, OM = obtuse marginal branch, MV = mitral valve, SP = septal perforator.

Figure 3

Photographs of cadaveric heart specimens showing the left ventricular summit (LVS) area with opened left coronary artery tree and overlying left atrial appendage (LAA). (A) Septal perforators (SPs) are visible in left anterior descending (LAD) artery with SP-1 being small and SP-2 being bigger and dominant. The great cardiac vein (GCV) is running below the SP; thus, the LVS has only an inaccessible area. (B) SPs located in the great proximity of the left coronary artery (LCA) ostium: the small SP-1 located in the left coronary artery (LCA) trunk and the dominant SP-2 located near the LCA bifurcation, thus defining a very small LVS area. (C,D) The LAA is located directly over the LVS area. Cx = circumflex branch of left coronary artery, PT = pulmonary trunk.

Figure 4

Photographs of the same cadaveric heart specimen dissected at two different levels showing spatial relationships between left ventricular summit (LVS), coronary vessels and aortic valve components. (A) Block of heart showing section lines through the LVS area; (B) Section 1, cut through the anterior interventricular groove (along the LVS septal margin); (C) Section 2, cut through the septal summit and the left coronary cusp of aortic valve. Violet asterisk = septal summit, black asterisk = aortic–mitral continuity, red asterisk = inaccessible area, Ao = aorta, AIV = anterior interventricular vein, AML = anterior mitral leaflet, AV = aortic valve, CV = conus vein, LA = left atrium, LAD = left anterior descending artery, LCA = left coronary artery, LV = left ventricle, OF = oval fossa, PT = pulmonary trunk, PV = pulmonary valve, PVC = posterior vein of conus, R-L ILT = right–left interleaflet triangle, RCC = right coronary cusp.