What are the characteristics of a "high-output" cardiac failure?

The characteristics of "high-output" cardiac failure primarily involve an increased cardiac output, which can be due to various pathological conditions that demand enhanced circulatory support. In this context, the option indicating increased cardiac output with normal or reduced systemic vascular resistance accurately encapsulates the hallmark feature of high-output failure.

In conditions such as hyperthyroidism, arteriovenous fistulae, or severe anemia, the body's demand for oxygen and nutrients increases significantly, prompting the heart to pump more blood—thereby elevating cardiac output. Despite this increase, the systemic vascular resistance may remain normal or even decrease as the vessels dilate to accommodate the heightened blood flow, illustrating the distinct nature of high-output failure when compared to other forms of heart failure where output is typically compromised.

This understanding distinguishes it from options that indicate either low cardiac output or decreased stroke volume, which are not representative of high-output cardiac failure. High-output failure is characterized specifically by the heart's inability to meet the body's metabolic demands, despite a relatively increased workload reflected in the output readings.