A nurse is assessing a pregnant client at 28 weeks gestation with a history of mitral valve stenosis. Which assessment finding would be the most concerning and require immediate intervention?

In a pregnant client with known mitral valve stenosis, the cardiovascular system faces a profound physiological challenge. Pregnancy increases plasma volume by approximately 40–50% and cardiac output by 30–50%. For a heart with a narrowed mitral valve, this volume load cannot be efficiently moved from the left atrium to the left ventricle. The result is a rise in left atrial and pulmonary venous pressures, which predisposes the patient to pulmonary congestion and acute decompensated heart failure. The second and third trimesters represent the period of peak hemodynamic stress, making this a critical window for monitoring cardiac decompensation ^[1].

The assessment finding of dyspnea at rest with orthopnea is the most concerning because it directly signals that the heart's compensatory mechanisms have been overwhelmed. Orthopnea—difficulty breathing when lying flat—indicates that pulmonary venous congestion is so severe that the supine position, which increases venous return to the right heart and subsequently to the pulmonary circuit, cannot be tolerated. This is a hallmark symptom of left-sided heart failure secondary to severe mitral stenosis ^[4]. In the context of pregnancy, this presentation is a sentinel sign of impending maternal cardiovascular collapse and requires immediate intervention to reduce preload and control heart rate ^[3].

Each option must be evaluated against the backdrop of normal pregnancy adaptations versus pathological states specific to valvular heart disease.

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  Option 1 (Dyspnea at rest with orthopnea): This is the correct answer. It is a direct clinical manifestation of cardiac decompensation. As the stenotic mitral valve obstructs forward flow, the left atrium dilates and pressure backs up into the pulmonary veins. When the patient lies down, fluid redistribution from the lower extremities and splanchnic circulation increases central blood volume, acutely raising pulmonary capillary wedge pressure and causing fluid transudation into the pulmonary interstitium and alveoli. This is a medical emergency that can rapidly progress to acute pulmonary edema ^[4].
  


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  Option 2 (Mild ankle edema at the end of the day): Dependent edema is a common and expected finding in the second and third trimesters. It results from venous compression by the gravid uterus and decreased plasma oncotic pressure. While it warrants monitoring, it is not an isolated indicator of acute cardiac decompensation in the absence of other signs like pulmonary crackles or jugular venous distension.
  


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  Option 3 (Heart rate of 90 beats per minute): A resting heart rate increase of 10–20 bpm is a normal physiological adaptation to pregnancy due to hormonal changes and increased blood volume. A rate of 90 bpm falls within the expected range and does not, by itself, signify decompensation. However, tachycardia is a concern in mitral stenosis because it shortens diastolic filling time, which can further elevate left atrial pressure. The key distinction here is that 90 bpm is a mild elevation, whereas a rate exceeding 110–120 bpm would be a more specific trigger for intervention.
  


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  Option 4 (Weight gain of 2 pounds in one week): In the second trimester, a weight gain of approximately 1 pound per week is typical. A gain of 2 pounds could reflect fluid retention, but it is a nonspecific and slower indicator. Sudden weight gain over a few days combined with dyspnea would be more alarming, but as a single finding, it does not demand the same urgency as dyspnea at rest with orthopnea, which reflects an immediate, life-threatening alteration in gas exchange.
  

The nurse's priority is to recognize the clinical syndrome of acute heart failure in the setting of structural heart disease. Dyspnea at rest and orthopnea indicate that the patient has transitioned from a compensated state to a decompensated state, where the left atrium can no longer handle the volume load. This finding necessitates immediate actions: placing the patient in an upright, legs-dependent position to reduce venous return, administering oxygen, notifying the provider for urgent echocardiographic evaluation and medical management (such as diuretics and beta-blockers), and preparing for possible emergent delivery or percutaneous balloon mitral valvotomy if the patient is at term ^[3]. The presence of these symptoms in a patient at 28 weeks gestation with known mitral stenosis is a high-risk scenario that can unmask or exacerbate previously stable disease ^[4].