Table 1. List of approaches to the LVS and possible ablation coverage in the individual regions.
Approach to LVSReachable LVS RegionReferences
Right ventricular outflow trackSeptal margin, right aspect of LVS accessible area, lower right septal summit[12,70]
Pulmonary trunk/left pulmonary arterySeptal margin, right aspect of LVS inaccessible area, higher right septal summit[6,73]
Aorta–left sinus of Valsalva/left coronary cuspSeptal summit, apex of LVS, aortic–mitral continuity[70,71,73,75,88]
Aorta–L-R inter leaflet trigonSeptal summit, apex of LVS[17,71,75,89]
Left atrial appendageMitral margin of LVS, accessible and inaccessible area (depends on the morphology and coverage of appendage)[68,70,83]
Great cardiac vein/anterior interventricular veinMitral margin of LVS, between accessible and inaccessible areas (depends on the course of venous system)[8,33,51,72,86,88,89]
Epicardial–subxiphoid accessAccessible area of LVS from septal to mitral margin[8,38,51,70,72,73,89]
 
The overview of publications focusing on ablations of ventricular arrhythmias arising from the LVS region with reported success and complication rates of procedures is presented in Table 2.
Table 2. Reported success and complication rates of LVS ventricular arrhythmia ablation procedures.
StudyLVS Access (if Specified)Total Number of CasesNumber of Successful CasesNumber of Complications
Obel, 2006 [33]TotalGCV550
Daniels, 2006 [72]Total11110
GCV9
Epi2
Yamada, 2008 [75]Total44441
LCC24
RCC14
NCC1
R-L ILT5
Kumagai, 2008 [73]Total45400
AMC3
MA8
LCC/RCC32
Epi2
Sacher, 2010 [85]TotalEpi136648
Yamada, 2010 [8]Total27220
GCV14
Epi4
Frankel, 2014 [12]RVOT220
Santangeli, 2015 [38]TotalEpi235no data
Yamada, 2015 [86]Total6458(only inaccesabile area failure)0
GCV36
AMC28
Marai, 2016 [71]Total10100
R-L ILT5
AIV-GCV1
NCC1
LCC2
RCC1
Hayashi, 2017 [70]Total1270
RVOT7
LCC1
AIV2
Epi2
Yamada, 2017 [87]not specified229212no data
Komatsu, 2018 [51]Total31  
GVC14101
other17170
Benhayon, 2018 [68]LAA110
Yakubov, 2018 [70]LAA110
Candemir, 2019 [88]not specified21150
Liao, 2020 [17]R-L ILT20160
Igarashi, 2020 [83]not specified18163
Chung, 2020 [89]Total2381997
GCV91
EPI6
RL ILT139
RL ILT = right–left interleaflet region, GCV = great cardiac vein, Epi = epicardial approach, RVOT = right ventricular outflow track, AMC = aortic–mitral continuity, LCC = left coronary cusp, NCC = noncoronary cusp, RCC = right coronary cusp, AIV = anterior interventricular vein, MA = mitral annulus.
10. Septal Summit/Septal Aspect of the LVS
Next to the LVS concept, the second idea of the so-called “septal summit” was proposed. The septal summit is the most superior part of the interventricular septum, located near the LVS septal margin, more toward the pulmonary trunk. The septal summit extends from the ventriculo-aortic junction down to the first dominant septal perforator (Figure 1). The structures neighboring the septal summit are the right–left interleaflet trigon from the top, the left pulmonary sinus from the right aspect and the anterior interventricular groove’s content from the lateral side. Above the apex of the LVS (under the left coronary artery), the septal summit corresponds with aortic–mitral continuity.
In contrast to the LVS, the septal summit cannot be reached from the left coronary aortic cusp, the left ventricular endocardial aspect or the left atrial appendage. It is worth emphasizing that the septal summit is central to the parasternal long-axis view in transthoracic heart ultrasound examination [90]. The above-mentioned right–left interleaflet trigon is adjacent to the mid-posterior septal aspect of the right ventricular outflow tract [91]. Within the septal summit, the conus vein and posterior veins of the cone, also known as communicating veins, can be present (Figure 4A) [51].
11. Conclusions
Providing systematic and comprehensive anatomical descriptions and proper terminology in the LVS region may facilitate the exchanging of 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 may be executed indirectly using the surrounding structures. 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.