CBSE Class 11-science Answered

In persons suffering with advanced heart condition, the artery gets constricted due to the accumulation of plaque on its inner walls.  In order to drive the blood through this constriction a greater activity of the heart is required. The speed of the flow of the blood in this region is raised which lowers the pressure inside, and the artery may collapse due to this external pressure.

The heart exerts further pressure to open this artery and forces the blood through. As the blood rushes through the opening, the internal pressure once again drops leading to a repeat collapse. This may result in heart attack.