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.

Magnetic Resonance Assessment of Ejection Fraction Versus Echocardiography for Cardioverter-Defibrillator Implantation Eligibility

“…So, Pinto et al, proposed another category of DCM entitled Hypokinetic nondilated cardiomyopathy (HNDC), based on LV or biventricular global systolic dysfunction without dilation (defined as LVEF < 45%), not explained by abnormal loading conditions or coronary artery disease, thus eliminating the strict need for a large left ventricular cavity [ 19 ]. The electric instability of the heart caused by the DCM can occur in any place of the heart, although some are considered as important sources of ventricular arrhythmias, such as the left ventricle summit, with a high level of difficulty for treatment [ 20 , 21 ]. Thus, not only can the modified dimensions of LV with low LVEF influence the need for and success of an ICD, but so can the anatomical and physiological modifications induced by DCMs.…”

Septal summit: A narrow epicardial region above the left ventricular summit. Implications for electrophysiological procedures

“…All are covered by various amounts of epicardial adipose tissue [8]. Arteries are represented by small septal perforating arteries exiting from the left main trunk or proximal aspect of the left anterior descending artery [4]. The veins leaving the superior septal and communicating veins, also known as the Vieussens veins, are combined with the conus vein.…”

“…Therefore, there is a need to identify new heart regions dependent on clinical and procedural aspects [2]. An example of this was identifying accurately the left ventricular summit (LVS) due to the difficulty in eliminating ventricular arrhythmias from this area (Figure 1B) [3,4]. A recent publication describing arrhythmias originating from non-epicardial LVS regions redefined a septal structure as the superior intraseptal site.…”

“…This intraseptal structure between the endocardial outflow tract and epicardial LVS was penetrated through the perforating arteries and the anterior vein branches of the heart [5]. While the anatomical boundaries of the left ventricular summit have been accurately described (Figure 1, white dotted line), the epicardial region located outside the septal margin, toward the right ventricular outflow tract is described as the septal summit (Figure 1, yellow asterisk) [4].…”

“…The septal summit as an anatomical term was proposed in 2021; nevertheless, in the literature, it is primarily described as the septal margin of the left ventricular summit [4,5]. According to the septal summit definition, these few millimeters (2-5 mm) are beyond the top of the left ventricle on the right side below the trunk of the left coronary artery.…”