High-output heart failure
Background
- High-output heart failure occurs when cardiac output is elevated but cannot meet the body's increased metabolic demands
- Unlike typical heart failure, the heart itself may be structurally normal initially
- Extremities are typically warm and well-perfused (distinguishing feature from low-output heart failure)
- Can progress to low-output failure if untreated
Clinical Features
- Dyspnea, fatigue, exercise intolerance
- Warm, well-perfused extremities (unlike cold/clammy in low-output failure)
- Bounding pulse with wide pulse pressure
- Peripheral edema, pulmonary congestion
- May have signs of underlying cause (goiter, AV fistula bruit, pallor)
Differential Diagnosis
- Hyperthyroidism
- Beriberi
- High-output heart failure from AV fistula
- AVM
- Paget disease
- Anemia
- Pregnancy
Common Causes
- Severe anemia (Hgb <5-7 g/dL)
- Hyperthyroidism / thyroid storm
- AV fistula (dialysis access, traumatic, congenital)
- Sepsis
- Paget's disease of bone
- Thiamine deficiency (wet beriberi)
- Pregnancy
- Cirrhosis
- Morbid obesity
Evaluation
- CBC: anemia
- TSH: hyperthyroidism
- BNP: elevated (not as reliable for distinguishing high vs. low output)
- Thiamine level if suspected deficiency (alcoholism, malnutrition)
- ECG: tachycardia, may show strain pattern
- CXR: cardiomegaly, pulmonary congestion
- Echocardiography: elevated EF (early), dilated chambers; eventually may show reduced EF
- Assess for AV fistula bruit (dialysis patients)
Management
- Treat underlying cause — this is definitive management
- Anemia: transfuse
- Hyperthyroidism: beta-blockers, antithyroid medications
- Sepsis: antibiotics, source control
- Thiamine deficiency: IV thiamine 500 mg before glucose
- AV fistula: may need ligation if causing heart failure
- Standard heart failure management for acute symptoms: diuretics for congestion, oxygen
- Avoid excessive volume removal in AV fistula-related heart failure
Disposition
- Admit: new diagnosis of heart failure, hemodynamic compromise, severe underlying cause (thyroid storm, sepsis, severe anemia)
- Discharge: mild symptoms with correctable cause identified and treated (e.g., anemia transfused, thyroid medication adjusted) with close follow-up