Which diagnostic test will be most useful to the nurse in determining whether a patient admitted with acute shortness of breath has heart failure?

Correct Answer: C

Rationale: B-type natriuretic peptide (BNP) is secreted when ventricular pressures increase, as they do with heart failure. Elevated BNP indicates a probable or very probable diagnosis of heart failure. A 12-lead electrocardiogram, arterial blood gases, and troponin may also be used in determining the causes or effects of heart failure but are not as clearly diagnostic of heart failure as BNP.

Correct Answer: A

Rationale: The rough parts of both atria (pectinate muscles) derive from the common primordial atrium in embryonic development.

Correct Answer: B

Rationale: An increased refractory period prevents re-entry circuits, reducing the risk of ventricular fibrillation.

Correct Answer: C

Rationale: Atrial fibrillation causes an irregular and often rapid ventricular rate due to erratic atrial impulses.

Correct Answer: C

Rationale: Elevated blood lactate levels confirm lactic acidosis.