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A 30-year-old member asked:

How can decreased cardiac output be caused by abnormal fluid volume?

2 doctor answers7 doctors weighed in
Dr. Bennett Werner
Cardiology 44 years experience
Physiology: The amount of blood the left ventricle can pump (stroke volume) is directly related to "preload" which is based on the venous return to the heart. If volume is contracted from bleeding, diuresis, vasodilation, or poor intake, preload is reduced, venous return is reduced, stroke volume is reduced &, if increased heart rate can't compensate for the reduction, then cardiac output is also reduced.
Dr. Islam Abudayyeh
Dr. Islam Abudayyehanswered
Cardiology 21 years experience
Overloading: Low cardiac function may not be able to keep up with too much volume and the fluid backs up in places like the lung, neck, abdomen, and legs. Too much volume can overwhelm a borderline heart already weak. When the heart cannot keep up the needed cardiac output (liters per min) and making the pump work harder increasing pressure inside the heart, and dilating the chamber getting into a bad cycle.
Dr. Bennett Werner
Cardiology 44 years experience
I hadn't read Dr. Abudayyeh's answer when I answered but I agree with him. He and I are describing 2 ends of the spectrum and both cause low cardiac output: he describes a diseased, overloaded heart and I describe a normal, underloaded heart. In both cases, the heart cannot pump a normal amount of blood.
Apr 20, 2012

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A 33-year-old member asked:

How is decreased cardiac output caused by increased fluid volume and decreased fluid volume?

3 doctor answers4 doctors weighed in
Dr. Rajat Jhanjee
Cardiology 20 years experience
Stroke volume: Cardiac output is determined by heart rate and volume of blood pumped by heart in each heartbeat (stroke volume). Increased fluid volume increases the stroke volume and therefore cardiac output. Decreased fluid volume decreases the stroke volume and therefore cardiac output.
A 34-year-old member asked:

How can decreased cardiac output be caused by either increased fluid volume and decreased fluid volume?

1 doctor answer1 doctor weighed in
Dr. Calvin Weisberger
Cardiology 51 years experience
Cardiac output: When systolic dysfunction is present, volume overloading can result in decreased stroke volume and cardiac output. In any cardiac status, decreased intravascular volume will result in decreased cardiac output.

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