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Blood Vessels and Myocardial Thickness within the Left Atrial Appendage Isthmus Line
Mateusz K Hołda1, Jakub Hołda1, Marcin Strona2
1HEART - Heart Embryology and Anatomy Research Team, Department of Anatomy, Jagiellonian University Medical College, Cracow, Poland.
Insights
This study reveals that the myocardium is thickest at the left atrial appendage (LAA) end of the isthmus. Understanding the myocardial architecture and epicardial vessels in the LAA isthmus is crucial for ablation procedures.
Area of Science:
- Anatomical studies
- Cardiac electrophysiology
- Surgical anatomy
Background:
- Left atrial appendage (LAA) isolation and linear ablations at the LAA base are increasingly common procedures.
- However, detailed knowledge of the myocardial architecture and epicardial vasculature in this specific region is limited.
- This lack of information may impact the safety and efficacy of cardiac ablation techniques.
Purpose of the Study:
- To investigate the myocardial thickness and vascular anatomy of the LAA isthmus.
- To identify the types and prevalence of epicardial arteries and veins in the LAA isthmus region.
- To provide anatomical data that can inform cardiac ablation procedures.
Main Methods:
- Examination of 200 autopsied human hearts.
- Longitudinal cutting of the LAA isthmus (line between LAA ostium and mitral annulus).
- Measurement of myocardial thickness and identification of epicardial blood vessels (arteries and veins).
Main Results:
- Myocardial thickness varied significantly along the LAA isthmus, being thickest at the LAA end (2.4 mm).
- Epicardial arteries were present in 96.5% of samples, with branches from the left circumflex coronary artery being most common.
- The great cardiac vein was found in 77.0% of hearts, and in 31.5% of cases, an artery was located between the endocardium and the great cardiac vein.
Conclusions:
- The LAA isthmus exhibits a specific myocardial architecture, with the thickest myocardium at the LAA end.
- Branches of the left circumflex coronary artery and the great cardiac vein are consistently found in the LAA isthmus.
- This detailed anatomical understanding is vital for optimizing the safety and effectiveness of LAA-related ablation procedures.
Abstract:
Electric isolation of the left atrial appendage (LAA) and linear ablations in the area of the LAA base are gaining popularity. However, very little is known about the myocardial architecture and the presence of epicardial blood vessels within this region, which could significantly influence the course of such procedures. We examined 200 autopsied hearts (22.5% females, 46.7 ± 16.8 years old). The LAA isthmus (i.e., the line between the LAA ostium and the mitral annulus) was cut longitudinally. The myocardium was thickest at the LAA end of the isthmus (2.4 ± 0.7 mm) followed by its middle sector (2.1 ± 0.7 mm) inside the LAA, 5 mm from its ostium (1.9 ± 0.7 mm), and the mitral annulus end of the isthmus (1.8 ± 0.6 mm) (P < 0.0001). At least one artery was found in 96.5% of all samples (89.5% were single branched, 7% had two branches). The great cardiac vein was found in 77.0% and the left marginal vein in 2.5%. The artery was interposed between the endocardium and the great cardiac vein in 31.5% of cases. The smallest distance between the endocardium and the artery was 0.5 mm and between the endocardium and the vein was 0.7 mm. In total, we were able to distinguish fifteen different types of vascular arrangements within the LAA isthmus line in this study. The myocardium within the LAA isthmus is thickest at its LAA end. The left circumflex coronary artery branches are the most frequently-occurring vessels within the isthmus and are present in almost all cases, while the great cardiac vein is present in three quarters of hearts. Clin. Anat. 31:1024-1030, 2018. © 2018 Wiley Periodicals, Inc.
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