Is the patient's constipation a sign of dehydration from increased furosemide (Lasix) dose and is the persistent swelling in the right lower extremity related to cardiac symptoms or other cardiac issues in a patient with Heart Failure with preserved Ejection Fraction (HFpEF)?

Constipation and Unilateral Edema in a Patient with HFpEF on Furosemide

The patient's constipation is likely due to dehydration from increased furosemide dosing, while the persistent right lower extremity edema is probably related to a localized vascular or lymphatic issue rather than cardiac causes, as it is unilateral and did not respond to diuretic therapy.

Constipation and Dehydration Assessment

Constipation is a common side effect of excessive diuresis with furosemide, particularly when the dose is increased rapidly as in this case. The FDA drug label for furosemide specifically warns about excessive diuresis causing dehydration and blood volume reduction 1. Several clinical findings support this connection:

• The constipation developed after doubling the furosemide dose
• The patient showed asymmetric response to diuresis (left leg improved while right did not)
• The patient did not see increased urine output with continued higher dosing

According to the ACC/AHA guidelines, diuretic therapy should aim to eliminate clinical evidence of fluid retention using the lowest dose possible to maintain euvolemia 2. Excessive diuresis can lead to:

• Volume depletion
• Electrolyte imbalances
• Gastrointestinal disturbances including constipation

Unilateral Edema Analysis

The persistent right lower extremity edema despite adequate diuretic therapy suggests a non-cardiac etiology. Key points to consider:

• Cardiac edema from HFpEF is typically bilateral and symmetric
• The patient showed improvement in left leg edema and dyspnea with diuresis
• Lack of response in the right leg despite adequate diuresis elsewhere

This pattern strongly suggests a localized vascular or lymphatic issue in the right leg rather than cardiac-related fluid retention. According to heart failure management guidelines, diuretics effectively relieve pulmonary and peripheral edema within hours or days when the edema is cardiac in origin 2.

Management Recommendations

1. For constipation:

   • Reduce furosemide back to 20 mg daily
   • Ensure adequate hydration (1.5-2 L/day) 3
   • Consider adding a gentle osmotic laxative (not stimulant laxatives)
   • Monitor daily weights to ensure euvolemia

2. For persistent right leg edema:

   • Obtain duplex ultrasound of right lower extremity to evaluate for deep vein thrombosis
   • Consider lymphatic evaluation if vascular studies are negative
   • Implement compression therapy for the right leg
   • Elevate the right leg when seated or lying down

3. For overall HFpEF management:

   • Maintain sodium restriction (2-4 g daily) 3
   • Continue appropriate GDMT for HFpEF alongside diuretic therapy
   • Monitor electrolytes, especially potassium, sodium, and magnesium 3
   • Implement daily weight monitoring to guide diuretic dosing 2

Pitfalls to Avoid

• Continuing to increase furosemide dose for unilateral edema could lead to worsening dehydration, constipation, and electrolyte abnormalities
• Assuming all edema in HFpEF patients is cardiac in origin can lead to inappropriate management
• Ignoring constipation as a sign of excessive diuresis can result in patient discomfort and medication non-adherence
• Failing to monitor electrolytes during diuretic dose adjustments increases risk of arrhythmias 1

The asymmetric response to diuresis is the key clinical clue that the right leg edema has a different etiology than the patient's cardiac condition. Addressing both issues separately will lead to better symptom control and improved quality of life.