Final answer:
Difficulty breathing and shortness of breath (dyspnea) are common manifestations of cardiac difficulties in a pregnant client with mitral valve stenosis.
Step-by-step explanation:
One manifestation that would indicate a nurse client at 28 weeks gestation with previously diagnosed mitral valve stenosis is experiencing cardiac difficulties is difficulty breathing and shortness of breath (dyspnea).
Other possible manifestations include swelling (edema) in the ankles and fatigue.
If the client experiences any of these manifestations, it's important for the nurse to assess the client's vital signs, oxygen saturation levels, and perform an electrocardiogram (ECG) to monitor the client's heart function.