Absolute and relative hypovolamia can be present.
Myocardial depression (LV and RV) is present in up to 60% in the 1st 3 days. It is caused by inflammatory mediators. This is known as a septic cardiomyopathy. 
Evidence suggests it associated with a worse outcome.
This extremely high incidence shows why echo is mandatory in septic shock to guide administration or withholding of fluids, vasopressors and inotropes.
Diastolic function can be affected on its own. It will always be impaired with systolic dysfunction.
The impairment of systolic and diastolic function means monitoring changes in PAOP is useful to assess tolerance to fluids, especially as non cardiogenic pulmonary oedema also occurs.
It should be noted that LV filling pressures can be normal or low in septic shock, even with systolic (and diastolic) dysfunction.
Dobutamine reliably increases cardiac output in sepsis. In some patients this is more because of an increase in HR rather that SV so the response (SV) should be assessed as those who increase their SV more are more likely to benefit.
Milrinone and levosimendan are alternative agents when dobutamine fails.

⅓ of patients have RV dysfunction. 
This may explain fluid unresponsiveness.
It may only be unmasked when IPPV is applied.

A septic cardiomyopathy (ventricular dysfunction) may cause false positives in stroke volume, pulse pressure and systolic pressure variations.

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