Does more blood enter the heart through the inferior vena cava or superior vena cava?

Answer 1

Wow, Is this an interesting question. My assumption would be a larger proportion entering the right atrium from the inferior route since the greater percentage of body mass - - major organs, muscle mass, etc - - is below the heart. I hope you get a more definitive answer. I'll send this to another doc, Yaybob, who may know this data. I hope you guys don't tell me it has to be the same. I don't remember the anatomy well enough to recall precisely the diameter of the lumens for the superior vs inferior cava. Perhaps we need a CV surgical person.

Added Note - Yaybob has the answer which fits with Mr. B's answer below. In an adult, it is about two thirds from the IVC and one third from the SVC.

Answer 2

The inferior vena cava returns more blood to the right atrium. The brain uses approximately 15% of cardiac output. My best guess would be around 30% for the superior vena cava. Keep in mind that circulation percentages will change depending on skeletal muscle use, digestion, respiration, blood pressure, gravity, etc. Many mechanisms can influence vascular resistance and thus distribution of blood.

Answer 3

Through both. The superior vena cava drains the part of the body cranial to the heart, and the inferior vena cava drains the part of the body caudal to the heart. They both enter the right atrium.

Answer 4

if you think about it, there is more blood in the lower part of the body than the upper part so i would think more blood enters through the inferior vena cava. The SVC drains only the head and neck area

Answer 5

I agree it is a good question. The renal blood flow represents 25 percent of blood flow, So I also suspect the greater flow would be via inferior vena cava.
With the anastomotic connection from above and below figured in the effect of gravity would just amplify the discrepancy.
Old Doc

Answer 6

Both.


Doesn't Really Answer your Q, as to Which is More Though.