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Compression of interventricular septum during right ventricular pressure loading.
G S Nelson1, E Y Sayed-Ahmed, C A Kroeker
1Departments of Medicine, Physiology and Biophysics and Civil Engineering, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
Summary
The interventricular septum experiences compressive stresses during pulmonary artery constriction, challenging the membrane theory. These stresses may contribute to septal ischemia in certain heart conditions.
Area of Science:
- Cardiovascular Physiology
- Biomechanical Engineering
Background:
- The interventricular septum's mechanics are often simplified to a membrane model.
- Abnormal septal motion occurs in conditions like pulmonary hypertension.
Purpose of the Study:
- To investigate mechanical stresses in the interventricular septum under abnormal loading.
- To determine if the septum behaves as a membrane or exhibits bending and compression.
Main Methods:
- Developed a 2D finite element model of the interventricular septum.
- Used hemodynamic and echocardiographic data from canine models.
- Applied measured ventricular pressures to the model under control and pulmonary artery constriction.
Main Results:
- End-bending moments were necessary to model the septum during pulmonary artery constriction, but not in control conditions.
- Significant circumferential compressive stresses developed in the septum during pulmonary artery constriction.
- Results contradict the unstressed membrane hypothesis.
Conclusions:
- The interventricular septum exhibits complex mechanical behavior beyond a simple membrane.
- Compressive stresses in the septum may play a role in unexplained ischemia.
- Finite element modeling provides insights into cardiac mechanics under altered loading conditions.