**Core Concept**
Beta blockers are a class of medications that reduce the workload on the heart by decreasing the heart rate and the force of contraction. They are commonly used to treat chronic heart failure (CHF) by improving symptoms and reducing morbidity and mortality.

**Why the Correct Answer is Right**
Beta blockers work by antagonizing the effects of beta-1 receptors in the heart, which are stimulated by the hormone epinephrine. This leads to a decrease in heart rate, contractility, and cardiac output. The use of beta blockers in CHF has been shown to reduce hospitalizations and mortality. They are particularly useful in patients with reduced ejection fraction (HFrEF) and are often used in combination with other medications such as ACE inhibitors and diuretics.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because beta blockers do not increase blood volume or cardiac output, which is a common misconception.
* **Option B:** This option is incorrect because beta blockers can actually reduce the risk of hospitalization and mortality in patients with CHF, rather than increasing it.
* **Option C:** This option is incorrect because beta blockers can be used in patients with CHF with preserved ejection fraction (HFpEF) to reduce symptoms and improve quality of life.

**Clinical Pearl / High-Yield Fact**
Beta blockers should be initiated at a low dose and gradually increased to minimize the risk of adverse effects such as hypotension and worsening heart failure. It's essential to monitor patients for signs of worsening heart failure, such as increased shortness of breath or fatigue, and adjust the dose accordingly.

**Correct Answer: D. Beta blockers do not increase blood volume or cardiac output in CHF.**