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Limitations in calculating left ventricular volume by two dimensional geometry--an exised canine heart study
K K Minezaki1, L M Wang, Y Yamada
1Department of Physiology 2, School of Medicine, Tokai University, Kanagawa, Japan.
Summary
Accurate left ventricular (LV) volume calculation requires careful consideration of internal structures and fixing pressure. Deviations increase with higher pressures and larger volumes, indicating LV shape complexity.
Area of Science:
- Cardiovascular Physiology
- Biomechanical Engineering
- Anatomical Modeling
Background:
- Accurate quantification of left ventricular (LV) volume is crucial for diagnosing and managing cardiac diseases.
- Traditional methods often simplify the complex geometry of the LV, potentially leading to inaccuracies.
Purpose of the Study:
- To evaluate the accuracy of different methods for calculating canine left ventricular volume.
- To assess the impact of fixing pressure and internal structures on volume measurement accuracy.
Main Methods:
- Silicone casting of canine left ventricles (n=76) under varying pressures.
- Creation of wax casts incorporating papillary muscles and trabeculae carneae.
- Comparison of cast volumes with calculations from area-length methods (ellipsoid, paraboloid) and silhouette projection (Chapman's method).
Main Results:
- Papillary muscles and trabeculae carneae constituted approximately 35% of LV volume at lower pressures, independent of heart size or dog weight.
- This ratio decreased at higher fixing pressures.
- Volume calculation errors increased with higher pressures and larger ventricular volumes, suggesting limitations of symmetrical models.
Conclusions:
- The complex geometry of the left ventricle cannot be accurately represented by ideal symmetrical models.
- Accurate volume estimation (<10% error) is achievable under low fixing pressures (<5 mmHg) or with small volumes (<50 ml).
- Fixing pressure and intra-cavity structures significantly influence left ventricular volume measurements.