Final answer:
A heart failure patient with a pulse of 90 beats per minute should be closely monitored for jugular vein distension, which indicates increased venous pressure and fluid overload, alongside other symptoms like decreased urine output and increased blood pressure.
Step-by-step explanation:
A patient newly diagnosed with heart failure admitted to the hospital with a pulse of 90 beats per minute should be closely monitored for several potential complications. Among these, the nurse should particularly observe for jugular vein distension, a sign that can indicate worsening heart failure due to increased pressure in the venous system and fluid overload. Jugular vein distension could be accompanied by other symptoms such as decreased urine output, increased blood pressure, and shortness of breath, all of which are concerning signs in a patient with heart failure. It is important to watch for these signs because early intervention can be critical in managing heart failure and preventing further complications.