@lacy2 Valerie, The right side of the heart is pumping blood to the lungs for oxygenation. Blood comes back from the lungs into the left side of the heart which is bigger by design because the left side pumps blood to the entire body. Arteries carry the oxygenated blood from the left side of the heart to the body, and veins return the oxygen depleted blood back to the right side of the heart. It makes sense then, that if the pump isn't functioning well, the blood backs up, and if that is the right side of the heart, it will back up into the veins. Gravity is a factor too, and veins have valves in them that close to prevent backward flow of blood, so with the ankles and feet being normally the lowest point, blood can pool there if the right side heart pump is not efficient. Arteries have muscular walls that contract in concert with the contractions in the heart. That is what you can feel in your pulse in an artery. The left side of the heart and arteries do all the work of delivering oxygenated blood, and the blood coasts back to the right side of the heart. The muscles in the body can help too a bit when contractions squeeze veins that are passing through them.

The heart is 4 chambered, and you can think of it as 2 pumps side by side that contract in unison. Each side has an atrium where the blood enters first, then blood passes through a valve into the larger chamber, the ventricle. The closing of the valve between chambers prevents the back flow of blood during the strongest contractions of the ventricles. There are also valves in the major arteries where the blood leaves the heart. Think of them as doors that open and close in perfect timing to prevent back flow.

To answer your question, sometimes things are not symmetrical in the body, and there could be other factors that affect blood flow. Blood pressure readings also vary if a person moves and change with stress levels. It can change moment to moment. I know that I can do some deep relaxed breathing and drop my blood pressure. A blood pressure reading is just a snapshot of what was happening at that instant.