Patients with high output heart failure present with dyspnea, tachypnea, non-productive cough, fatigability, pulmonary rales, pleural effusion and peripheral edema, as a result of pulmonary and venous congestion due to neurohormonal activation and increased salt and water retention. Also, they are often tachycardic, with a heart rate between 85 and 105 beats per minute. A third heart sound and bilateral basal crackles are often heard in these patients [1]. Jugular and femoral venous hum may be sometimes observed. Peripheral vasodilatation leads to warm extremities.

High output heart failure is caused by a number of conditions each with their own signs and symptoms, that can sometimes also be found in affected individuals, such as chronic anemia, systemic arterio-venous fistulae, Paget's disease, hyperthyroidism, chronic hypercapnia, obesity, beriberi heart disease and sepsis.

Anemia causes cutaneous pallor and fatigability which overlaps with that induced by the heart failure, peripheral vasodilatation caused by vascular nitric oxide synthase [2] and low systemic vascular resistance [3].

Arteriovenous fistulae are associated with a specific hum on auscultation and may be congenital or acquired. They lead to a decrease in the systemic vascular resistance and thus high output heart failure [4]. Fistulae may be found in the context of certain congenital diseases, such as Osler-Weber-Rendu disease, Parkes-Weber or Klippel–Trénaunay syndrome. They can cause decreased pulse pressure distal to their location [1].

Paget's disease is associated with pain and warmth of the affected area, but a large amount of bone must be involved before heart failure occurs. A similar mechanism for the malfunction of the heart has been described in multiple myeloma, and Albright's disease [5].

Hypercapnia caused by chronic obstructive pulmonary disease may also cause high output heart failure [6]. The pulmonary pathology is recognized by auscultation and symptoms like dyspnea and fatigability.

Hyperthyroidism causes tachycardia-mediated cardiomyopathy and thus high output heart failure [7] and is often accompanied by atrial fibrillation [8].

Sepsis causes systemic vasodilatation, arterial hypotension and heart failure [9] and is recognized most often using laboratory workup, but also by fever, tachycardia, and tachypnea.

Beriberi is associated with chronic alcohol consumption or impaired nutrient absorption, that lead to weight loss and steatorrhea. Heart beriberi causes peripheral edema and fatigability and decreased systemic vascular resistance, leading to high output heart failure.

Obesity leads to systolic and diastolic malfunction of the heart and increased total blood volume, thus causing high output heart failure [10].

Blood workup shows elevated levels of atrial and brain natriuretic peptide in high output heart failure patients [11] [12]. Venous oxygen saturation, if high (above 75%), is an indirect indicator of a high output state. The oxygen content of arterial and mixed venous blood samples is expected to be decreased.

As in all heart failure individuals, a chest radiography is useful, as it might show cardiomegaly, pleural effusion or pulmonary congestion. A diagnosis of pneumonia in a septic patient with high output heart failure should lead the physician to suspect it as the underlying cause of the failure.

The diagnosis is ultimately confirmed with echocardiography showing an increased cardiac index. This investigation may show eccentric remodeling, chamber dilatation, and increased ventricular filling pressures, with a high ejection fraction. Pulmonary hypertension is another common finding in these patients.

Cardiac catheterization confirms increased cardiac filling pressures, high pulmonary artery pressure, stroke volume, ventricular preload, ejection fraction and decreased afterload as a result of low systemic vascular resistance [13].

Treatment of high-output heart failure focuses on addressing the underlying cause of the condition. For instance, if anemia is the culprit, iron supplements or blood transfusions may be necessary. In cases of hyperthyroidism, medications to control thyroid hormone levels are prescribed. Additionally, diuretics may be used to manage fluid retention, and lifestyle modifications, such as dietary changes and exercise, can help improve overall heart health.

The prognosis for high-output heart failure varies depending on the underlying cause and the effectiveness of treatment. If the root cause is identified and managed effectively, patients can experience significant improvement in symptoms and quality of life. However, if left untreated, high-output heart failure can lead to complications such as arrhythmias and worsening heart function.

High-output heart failure can result from various conditions that increase the body's demand for blood flow. Common causes include severe anemia, hyperthyroidism (overactive thyroid), arteriovenous fistulas (abnormal connections between arteries and veins), and certain nutritional deficiencies. These conditions lead to increased metabolic activity, requiring the heart to pump more blood to meet the body's needs.

High-output heart failure is relatively rare compared to other forms of heart failure. It is more commonly seen in populations with a higher prevalence of conditions like anemia and hyperthyroidism. The condition can affect individuals of any age, but the underlying causes may vary based on demographic factors such as age, gender, and geographic location.

In high-output heart failure, the heart compensates for increased metabolic demands by pumping more blood. However, this increased cardiac output is insufficient to meet the body's needs, leading to symptoms of heart failure. The heart's increased workload can eventually lead to structural changes and impaired function, exacerbating the condition.

Preventing high-output heart failure involves managing risk factors and underlying conditions. Regular medical check-ups can help detect and treat conditions like anemia and hyperthyroidism early. Maintaining a healthy lifestyle, including a balanced diet and regular exercise, can also reduce the risk of developing conditions that contribute to high-output heart failure.

High-output heart failure is a unique form of heart failure characterized by an increased cardiac output that fails to meet the body's demands. It is often caused by conditions that elevate metabolic activity, such as anemia and hyperthyroidism. Diagnosis involves identifying the underlying cause, and treatment focuses on managing these conditions. With appropriate intervention, patients can experience significant improvement in symptoms and quality of life.

If you or someone you know is experiencing symptoms like shortness of breath, fatigue, or swelling, it is important to seek medical evaluation. High-output heart failure is a condition where the heart works harder than normal but still cannot meet the body's needs. It can be caused by various underlying health issues, and treatment is available to address these causes and improve symptoms. Regular check-ups and a healthy lifestyle can help prevent conditions that lead to high-output heart failure.

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