Fast standing and the heart's insufficient accommodation of the increased venous return
Raoul's gives sensible comments:


ventricle overloading not sensible
retrosternal pain $\to$ myocardial ischemia
other cause reminding retrosternal pain such as celiac disease:


Posterior 1/3 of the septum is supplied by the following artery where any ischemia can weaken the isovolumetric contraction (TODO this has to be discussed much more carefully):


ischemia coronariaea posterioris created by problem in ramus interventricularis posterior arteriae coronariae dextrae