Inter-ventricular septum is generally in parallel alignment with Anterior aspect of root of aorta.
Have a look at this echo form a 65year old man
Note the classical bend of basal IVS encroaching the LVOT. Aortic valve opens normally.
The basal septum Projecting into LVOT
Pseudo LVOT gradient. It was about 25mmhg which is not significant.
- Sigmoid shaped IVS can cause a unique LVOT profile .
- Present in elderly . The exact mechanism and mechanical and hemodynamic implications are not known .
- It can rarely cause dynamic LVOT obstruction.
- When these patients develop Infero posterior MI there could be further collapse of IVS into LVOT .
Relationship between Aortic angle , Hypertension, HCM
Many of the HCM patients may show similar features .When ASH is confined only to basal IVS. HCM should not be diagnosed instead it is often a defect of aorta /IVS alignment .
Abnormal aortic angle with that of IVS may make the IVS appear sigmoid.
If patients with abnormally angled aorta develop hypertension ASH and sigmoid septum is more pronounced .
IVS dragging by mass effect on aortic root is possible and Aortic regurgitation may ensue
Reference
Dr.S.Venkatesan MD 
