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A change in cardiac output without any change in the heart rate, pulmonary artery wedge pressure (PAWP = equated to preload) or systemic vascular resistance (SVR = afterload) would have to be due to a change in the contractility of the heart.

Cardiac output (CO) is roughly equal to stroke volume x heart rate.

Stroke volume is related to preload, contractility, and afterload.

As you can see, the only variables you have not controlled for is cardiac contractility.

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Q: What decreases cardiac output without change in heart rate PAWP or SVR Is it preload afterload or contractility?
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In a healthy individual which of the following would be low Contractility Preload Stroke volume or Afterload.?

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